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Sample records for optic hydrophone probe

  1. Thin film metal coated fiber optic hydrophone probe.

    Science.gov (United States)

    Gopinath Minasamudram, Rupa; Arora, Piyush; Gandhi, Gaurav; Daryoush, Afshin S; El-Sherif, Mahmoud A; Lewin, Peter A

    2009-11-01

    Our purpose is to improve the performance sensitivity of a fiber sensor used as a fiber optic hydrophone probe (FOHP) by the addition of nanoscale thin film gold coating. The fiber is designed to provide a uniform and spatial averaging free response up to 100 MHz by etching down to an active diameter of approximately 9 mum. The performance sensitivity of straight cleaved (i.e., full size core and cladding) uncoated, tapered uncoated, and tapered thin film gold-coated fiber sensors was compared in the frequency range from 1.5 to 20 MHz in the presence of acoustic amplitude pressure levels as high as 6 MPa. An unprecedented voltage sensitivity of -245 dB relative to 1 V/muPa (560 mV/MPa) was measured for a thin film gold-coated FOHP by optimizing the gold coating thickness.

  2. Acousto-optic, point receiver hydrophone probe for operation up to 100 MHz.

    Science.gov (United States)

    Lewin, P A; Mu, C; Umchid, S; Daryoush, A; El-Sherif, M

    2005-12-01

    This work describes the results of initial evaluation of a wideband acousto-optic hydrophone probe designed to operate as point receiver in the frequency range up to 100 MHz. The hydrophone was implemented as a tapered fiber optic (FO) probe sensor with a tip diameter of approximately 7 microm. Such small physical dimensions of the sensor eliminate the need for spatial averaging corrections so that true pressure-time (p-t) waveforms can be faithfully recorded. The theoretical considerations that predicted the FO probe sensitivity to be equal to 4.3 mV/MPa are presented along with a brief description of the manufacturing process. The calibration results that verified the theoretically predicted sensitivity are also presented along with a brief description of the improvements being currently implemented to increase this sensitivity level by approximately 20 dB. The results of preliminary measurements indicate that the fiber optic probes will exhibit a uniform frequency response and a zero phase shift in the frequency range considered. These features might be very useful in rapid complex calibration i.e. determining both magnitude and phase response of other hydrophones by the substitution method. Also, because of their robust design and linearity, these fiber optic hydrophones could also meet the challenges posed by high intensity focused ultrasound (HIFU) and other therapeutic applications. Overall, the outcome of this work shows that when fully developed, the FO probes will be well suited for high frequency measurements of ultrasound fields and will be able to complement the data collected by the current finite aperture piezoelectric PVDF hydrophones.

  3. Comparative experiments between a conventional piezo hydrophone system and a fibre optic hydrophone system

    NARCIS (Netherlands)

    Cheng, L.K.; Bruijn, D. de

    2000-01-01

    We report here the results of comparative measurements between Fibre Optic (FO) hydrophone system with our Hydrostatic Pressure Conmpensation (HPC) mechanism and a conventional piezo hydrophone system (consisting of an ITC 1042 hydrophone and a B&K2035 Analyser). The sensitivity and the dynamic rang

  4. DIRECTIVITY PATTERN INVESTIGATION OF DUAL FIBER OPTIC HYDROPHONE

    Directory of Open Access Journals (Sweden)

    M. E. Efimov

    2015-11-01

    Full Text Available Subject of Research. The paper provides comparison of theoretical and experimental research results of directivity pattern of dual fiber optic hydrophone at various acoustic frequencies. Application of multiple fiber optic transducers in fiber optic hydrophone design placed in sensitive arm of the interferometer gives the possibility for increasing the sensitivity of a fiber optic hydrophone without changing the fiber-optic transducers. In the simplest case, such fiber optic hydrophone can be built on the basis of two spatially separated acoustic transducers. However, this diversity inevitably leads to the directivity pattern unevenness of the fiber optic hydrophone at acoustic frequencies which wavelengths are commensurate with the size of the transducers system. Method. Mathematical model has been created and it became the base material for a theoretical study of two acoustic transducers system in Mathcad environment. Directivity pattern was described by a mathematical formula, depending on the frequency of the acoustic impact and the distance between sensors. To confirm the correctness of theoretical research of the directivity pattern, dual fiber optic hydrophone on Bragg gratings was produced and investigated experimentally. It consists of two consequently welded sensitive elements with a 9 cm distance between them. In trials carried out in open water conditions, fiber-optic hydrophone was placed on the rotator and rotated relative to the piezoceramic emitter for 360 degrees. During investigation, the signal from a fiber optic hydrophone has been recorded simultaneously with the rotation. Further, after the data processing in MATLAB, amplitude of the measured phase signal and the directivity pattern of the test sample were estimated. Amplitude estimation of the measured phase signal and directivity pattern creation of the sample was performed at frequencies equal to 1000, 3000 and 8000 Hz. Main Results. Sensitivity of the dual fiber optic

  5. Pseudo working-point control measurement scheme for acoustic sensitivity of interferometric fiber-optic hydrophones

    Institute of Scientific and Technical Information of China (English)

    Zefeng Wang; Yongming Hu; Zhou Meng; Ming Ni

    2008-01-01

    A novel pseudo working-point control measurement scheme for the acoustic sensitivity of interferometric fiber-optic hydrophones is described and demonstrated.The measurement principle is introduced in detail.An experimental system,which interrogates an interferometric fiber-optic hydrophone with this method,is designed.The acoustic pressure phase sensitivity of the fiber-optic hydrophone is measured over the frequency range of 20-2500Hz.The measured acoustic sensitivity is about-156.5dB re 1rad/μPa with a fluctuation lower than ±1.2dB,which is in good agreement with the results obtained by the method of phase generated carrier.The experimental results testify the validity of this new method which has the advantages of no electric elements in the sensing head,the simplicity of signal processing,and wide working bandwidth.

  6. MODELING AND EXPERIMENTAL STUDY OF A FIBER OPTIC HYDROPHONE SENSING ELEMENT

    Directory of Open Access Journals (Sweden)

    Mikhail E. Efimov

    2014-09-01

    Full Text Available A model of the fiber-optic hydrophone sensor is suggested. Hydrophone construction comprises a malleable core made of a polymeric material with regulated elastic properties to which the optical fiber is wound. The built-in module of Comsol Multiphysics - Acoustic Solid Interaction is used in the simulation; it evaluates the impact of the acoustic field of different frequencies and amplitudes on the value of the sensor surface deformation. The proposed model gives the possibility for simulating the hydrophone in various environments; materials and dimensions of sensor are selected at the design stage to ensure the required performance: frequency response and sensitivity of fiber optic hydrophone. Correctness of the model construction was verified by results comparison of the computer simulation and experimental study in the acoustic pool. The prototype was represented as the phase interferometric fiber-optic hydrophone on the Bragg gratings. The sensing element is formed as a cylindrical core round which the optical fiber is wound. Core characteristics are: the material attenuation (damping – 0.1, Young's modulus of the core - 6 MPa, Poisson’s ratio - 0.49. The prototype was tested in the experimental pool, which design makes it possible to carry out measurements at frequencies above 3 kHz in the absence of reflections of the acoustic signal. The impact assessment of the acoustic field is carried out by means of an approved piezoelectric hydrophone: the amplitude of the acoustic field of a plane wave is 0.5 and 1 Pa, frequencies of the acoustic impact are 3000 - 8000 Hz. According to the findings fabricated prototype sensitivity was equal to 0.1 rad / Pa at the frequency of 3 kHz. Studies have shown that the sensitivity of the simulated fiber optic hydrophone will decrease with increasing frequency of hydroacoustic exposure. At 8 kHz frequency the sensitivity is decreased to 0.01 rad / Pa. Prototype testing results have confirmed the adequacy

  7. Experimental Investigation on a Fibre-Optic Hydrophone with a Cylindrical Helmholtz Resonator

    Institute of Scientific and Technical Information of China (English)

    WANG Ze-Feng; HUNG Yong-Ming; MENG Zhou; NI Ming

    2008-01-01

    A novel mechanical anti-aliasing filtering fibre-optic hydrophone with a cylindrical Helmholtz resonator is constructed and tested.The experimental results show that the hydrophone has a function of low-pass filtering.The low frequency acoustic sensitivity is about -160 dB (1 rad/μPa),and the response curve has a resonance determined by the Helmholtz resonator.Theoretical and experimental results both show that the resonant frequency moves towards high frequency with the increasing orifice diameters.The sensitivity attenuation of high frequency is larger than 10 dB.This new fibre-optic hydrophone is a prototype device for a c/ass of sensors used to eliminate the aliasing in future sonar systems.

  8. Fiber-optic ultrasonic hydrophone using short Fabry-Perot cavity with multilayer reflectors deposited on small stub.

    Science.gov (United States)

    Kim, Kyung-Su; Mizuno, Yosuke; Nakamura, Kentaro

    2014-04-01

    A fiber-optic probe with dielectric multilayer films deposited on a small stub is studied for mega-hertz ultrasonic-wave detection in water. The small stub with a short Fabry-Perot cavity and distributed reflectors is attached on the fiber end. The structure is mechanically strong and withstands intense ultrasonic pressure. Ultrasonic waves at 1.56MHz are successfully detected in water with a good signal-to-noise ratio. The working principle and the characteristics are studied by comparing the ultrasonic sensitivity with that of a conventional piezoelectric hydrophone. The distance response and directional response are also investigated.

  9. A wideband connection to sperm whales: A fiber-optic, deep-sea hydrophone array

    DEFF Research Database (Denmark)

    Heerfordt, Anders; Møhl, Bertel; Wahlberg, Magnus

    2007-01-01

    A 10-element, 950 m long, vertical hydrophone array based on fiber-optic data transmission has been developed primarily for studying the beam pattern from deep diving cetaceans emitting sonar pulses. The array elements have a configurable sampling rate and resolution with a maximum signal bandwidth...

  10. In-plane ultrasonic needle tracking using a fiber-optic hydrophone

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Wenfeng, E-mail: wenfeng.xia@ucl.ac.uk; Desjardins, Adrien E. [Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT (United Kingdom); Mari, Jean Martial [Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom and GePaSud, University of French Polynesia, Faa’a 98702, French Polynesia (France); West, Simeon J. [Department of Anaesthesia, University College Hospital, Main Theatres, Maple Bridge Link Corridor, Podium 3, 235 Euston Road, London NW1 2BU (United Kingdom); Ginsberg, Yuval; David, Anna L. [Institute for Women’s Health, University College London, 86-96 Chenies Mews, London WC1E 6HX (United Kingdom); Ourselin, Sebastien [Center for Medical Imaging Computing, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2015-10-15

    Purpose: Accurate and efficient guidance of needles to procedural targets is critically important during percutaneous interventional procedures. Ultrasound imaging is widely used for real-time image guidance in a variety of clinical contexts, but with this modality, uncertainties about the location of the needle tip within the image plane lead to significant complications. Whilst several methods have been proposed to improve the visibility of the needle, achieving accuracy and compatibility with current clinical practice is an ongoing challenge. In this paper, the authors present a method for directly visualizing the needle tip using an integrated fiber-optic ultrasound receiver in conjunction with the imaging probe used to acquire B-mode ultrasound images. Methods: Needle visualization and ultrasound imaging were performed with a clinical ultrasound imaging system. A miniature fiber-optic ultrasound hydrophone was integrated into a 20 gauge injection needle tip to receive transmissions from individual transducer elements of the ultrasound imaging probe. The received signals were reconstructed to create an image of the needle tip. Ultrasound B-mode imaging was interleaved with needle tip imaging. A first set of measurements was acquired in water and tissue ex vivo with a wide range of insertion angles (15°–68°) to study the accuracy and sensitivity of the tracking method. A second set was acquired in an in vivo swine model, with needle insertions to the brachial plexus. A third set was acquired in an in vivo ovine model for fetal interventions, with insertions to different locations within the uterine cavity. Two linear ultrasound imaging probes were used: a 14–5 MHz probe for the first and second sets, and a 9–4 MHz probe for the third. Results: During insertions in tissue ex vivo and in vivo, the imaged needle tip had submillimeter axial and lateral dimensions. The signal-to-noise (SNR) of the needle tip was found to depend on the insertion angle. With

  11. Measurement of sound field in cavitating media by an optical fibre-tip hydrophone.

    Science.gov (United States)

    Koch, Christian; Jenderka, Klaus-Vitold

    2008-04-01

    A fibre-optic technique was applied to measure the sound field in an ultrasonic cleaning vessel under practical conditions. A metal-coated fibre-tip is used as a sensor and a heterodyne interferometer detects the change in the optical path resulting from the movement of the fibre-tip in the sound field. Spectrally resolved sound field parameters such as the fundamental, the subharmonic or cavitation noise are extracted from the measurements and compared with results obtained by a piezo-electric hydrophone. It was found that the fibre sensor provides a signal related to the velocity in the sound field, but the information about cavitation-related parameters is similar to the information for pressure sensing techniques. The fibre-optic sensors have a uniquely high spatial resolution and the sound detection process is strongly influenced by single cavitation events close to the small fibre-tip. This paper shows that fibre-tip sensors are an alternative to common hydrophone techniques. They can open up new possibilities for measurement problems for which so far no solution exists, in particular when a high spatial resolution is required or when the measurement site is small.

  12. Research on fiber-optic interferometric hydrophone array using frequency division multiplying technique

    Institute of Scientific and Technical Information of China (English)

    CAO Jianian; LI Xuyou; WANG Zhaoxia; LUO Jicheng; FU Lintai

    2001-01-01

    From the point of view of system design, a configuration of fiber-optic interferometric hydrophone array and its modulation and demodulation approach using frequency division multiplexing technique based on Phase Generated Carrier (PGC) is introduced. And the emphasis on demonstrating the relationship among the number of units N, the detectable signal amplitude D and the detectable frequency ωs through analyzing the frequency spectrum of the output signal of the J × K array and the key factor which restricts N, D, ωo for increasing are presented. The maximum phase shift and the law of its variation according to frequency are specially analyzed. The results induced from some relative theory were verified by experiments.

  13. Experimental investigation of the thin fiber-optic hydrophone array based on fiber Bragg gratings

    Science.gov (United States)

    Lavrov, Vladimir S.; Plotnikov, Mikhail Y.; Aksarin, Stanislav M.; Efimov, Mikhail E.; Shulepov, Vladimir A.; Kulikov, Andrey V.; Kireenkov, Alexander U.

    2017-03-01

    The paper presents the results of experimental investigations of the fiber optic hydrophone array consisting of six sensors, placed in one thin sensitive cable. Sensors were formed by pairs of Bragg gratings spaced 1.5 m apart and recorded in a birefringent optical fiber with the elliptical stressed coating. To form an extended sensor array the optical fiber was additionally covered with a silicone material RTV655 and protective coatings. Experimental investigations of the array showed that fiber-optic sensors pressure sensitivity increases as the acoustic frequency decreases at average value from -169.4 dB re rad/uPa at 495 Hz to -143.7 dB re rad/uPa at 40 Hz. The minimum detectable pressure was at average value from 53 mPa/√Hz at 495 Hz to 8.3 mPa/√Hz at 40 Hz. The obtained results might be used for developing and producing long thin hydroacoustic arrays for geophysical investigations and other hydroacoustic applications.

  14. Optic probe for semiconductor characterization

    Science.gov (United States)

    Sopori, Bhushan L.; Hambarian, Artak

    2008-09-02

    Described herein is an optical probe (120) for use in characterizing surface defects in wafers, such as semiconductor wafers. The optical probe (120) detects laser light reflected from the surface (124) of the wafer (106) within various ranges of angles. Characteristics of defects in the surface (124) of the wafer (106) are determined based on the amount of reflected laser light detected in each of the ranges of angles. Additionally, a wafer characterization system (100) is described that includes the described optical probe (120).

  15. Optical imaging probes in oncology.

    Science.gov (United States)

    Martelli, Cristina; Lo Dico, Alessia; Diceglie, Cecilia; Lucignani, Giovanni; Ottobrini, Luisa

    2016-07-26

    Cancer is a complex disease, characterized by alteration of different physiological molecular processes and cellular features. Keeping this in mind, the possibility of early identification and detection of specific tumor biomarkers by non-invasive approaches could improve early diagnosis and patient management.Different molecular imaging procedures provide powerful tools for detection and non-invasive characterization of oncological lesions. Clinical studies are mainly based on the use of computed tomography, nuclear-based imaging techniques and magnetic resonance imaging. Preclinical imaging in small animal models entails the use of dedicated instruments, and beyond the already cited imaging techniques, it includes also optical imaging studies. Optical imaging strategies are based on the use of luminescent or fluorescent reporter genes or injectable fluorescent or luminescent probes that provide the possibility to study tumor features even by means of fluorescence and luminescence imaging. Currently, most of these probes are used only in animal models, but the possibility of applying some of them also in the clinics is under evaluation.The importance of tumor imaging, the ease of use of optical imaging instruments, the commercial availability of a wide range of probes as well as the continuous description of newly developed probes, demonstrate the significance of these applications. The aim of this review is providing a complete description of the possible optical imaging procedures available for the non-invasive assessment of tumor features in oncological murine models. In particular, the characteristics of both commercially available and newly developed probes will be outlined and discussed.

  16. Tunable nanowire nonlinear optical probe

    Energy Technology Data Exchange (ETDEWEB)

    Nakayama, Yuri; Pauzauskie, Peter J.; Radenovic, Aleksandra; Onorato, Robert M.; Saykally, Richard J.; Liphardt, Jan; Yang, Peidong

    2008-02-18

    One crucial challenge for subwavelength optics has been thedevelopment of a tunable source of coherent laser radiation for use inthe physical, information, and biological sciences that is stable at roomtemperature and physiological conditions. Current advanced near-fieldimaging techniques using fiber-optic scattering probes1,2 have alreadyachieved spatial resolution down to the 20-nm range. Recently reportedfar-field approaches for optical microscopy, including stimulatedemission depletion (STED)3, structured illumination4, and photoactivatedlocalization microscopy (PALM)5, have also enabled impressive,theoretically-unlimited spatial resolution of fluorescent biomolecularcomplexes. Previous work with laser tweezers6-8 has suggested the promiseof using optical traps to create novel spatial probes and sensors.Inorganic nanowires have diameters substantially below the wavelength ofvisible light and have unique electronic and optical properties9,10 thatmake them prime candidates for subwavelength laser and imagingtechnology. Here we report the development of an electrode-free,continuously-tunable coherent visible light source compatible withphysiological environments, from individual potassium niobate (KNbO3)nanowires. These wires exhibit efficient second harmonic generation(SHG), and act as frequency converters, allowing the local synthesis of awide range of colors via sum and difference frequency generation (SFG,DFG). We use this tunable nanometric light source to implement a novelform of subwavelength microscopy, in which an infrared (IR) laser is usedto optically trap and scan a nanowire over a sample, suggesting a widerange of potential applications in physics, chemistry, materials science,and biology.

  17. Research on interferometric photonic crystal fiber hydrophone

    Science.gov (United States)

    Luo, Hong; Zhang, Zhen-hui; Wang, Fu-yin; Xiong, Shui-dong

    2013-08-01

    Current research on photonic crystal fiber (PCF) for acoustic sensing was focused on the PCF's pressure sensitivity enhancement. However, whether the enhancement of the PCF's pressure sensitivity can be actually realized is still controversial. Practical hydrophone, utilizing PCFs, to manifest its superior sensitivity to normal single mode fibers (SMFs) for acoustic sensing, should be made. Account to this point of view, actual hydrophone was fabricated. Index guiding PCF was used, the fiber core is solid silicon dioxide (SiO2), and the cladding is SiO2 filled with lots of periodical transverse circular air hollows. The PCF, mounted on an air-backed mandrel for structural sensitivity enhancement, was used as a sensing arm of the fiber Michelson interferometer. The other arm, so called reference arm, was made of SMF. Faraday rotator mirrors (FRM) were spliced in the end of each interferometric arm account for polarization induced phase fading, which is a common scheme in fiber interferometric sensing systems. A similar hydrophone, with all the same structure except that the PCF was exchanged into SMF, was also fabrication to make the contrast. The narrowlinewidth and frequency-tunable optical fiber laser was used to achieve high accuracy optical interferometric measurement. Meanwhile, the phase generated carrier (PGC) modulation-demodulation scheme was adopted to interrogate the measurand signal. Experiment was done by using acoustic standing-wave test apparatus. Linearity characteristics of the two hydrophones were measured at frequency 100Hz, 500Hz, and 1000Hz, experimental results showed that the maximum error of the linearity was 10%, a little larger than the theoretical results. Pressure sensitivities of the PCF hydrophone and the SMF hydrophone were measured using a reference standard PZT hydrophone in the frequency range from 20 Hz to 1600 Hz, the measurement data showed that the sensitivity of the PCF hydrophone was about -162.8 dB re. rad/μPa, with a

  18. High pressure optical combustion probe

    Energy Technology Data Exchange (ETDEWEB)

    Woodruff, S.D.; Richards, G.A.

    1995-06-01

    The Department of Energy`s Morgantown Energy Technology Center has developed a combustion probe for monitoring flame presence and heat release. The technology involved is a compact optical detector of the OH radical`s UV fluorescence. The OH Monitor/Probe is designed to determine the flame presence and provide a qualitative signal proportional to the flame intensity. The probe can be adjusted to monitor a specific volume in the combustion zone to track spatial fluctuations in the flame. The probe is capable of nanosecond time response and is usually slowed electronically to fit the flame characteristics. The probe is a sapphire rod in a stainless steel tube which may be inserted into the combustion chamber and pointed at the flame zone. The end of the sapphire rod is retracted into the SS tube to define a narrow optical collection cone. The collection cone may be adjusted to fit the experiment. The fluorescence signal is collected by the sapphire rod and transmitted through a UV transmitting, fused silica, fiber optic to the detector assembly. The detector is a side window photomultiplier (PMT) with a 310 run line filter. A Hamamatsu photomultiplier base combined with a integral high voltage power supply permits this to be a low voltage device. Electronic connections include: a power lead from a modular DC power supply for 15 VDC; a control lead for 0-1 volts to control the high voltage level (and therefore gain); and a lead out for the actual signal. All low voltage connections make this a safe and easy to use device while still delivering the sensitivity required.

  19. Electroless nickel plating on optical fiber probe

    Institute of Scientific and Technical Information of China (English)

    Li Huang; Zhoufeng Wang; Zhuomin Li; Wenli Deng

    2009-01-01

    As a component of near-field scanning optical microscope (NSOM),optical fiber probe is an important factor influncing the equipment resolution.Electroless nickel plating is introduced to metallize the optical fiber probe.The optical fibers are etched by 40% HF with Turner etching method.Through pretreatment,the optical fiber probe is coated with Ni-P film by clectrolcss plating in a constant temperature water tank.Atomic absorption spectrometry (AAS),scanning electron microscopy (SEM),and energy dispersive X-ray spectrometry (EDXS) are carried out to charaeterizc the deposition on fiber probe.We have rcproducibly fabricated two kinds of fiber probes with a Ni-P fihn:aperture probe and apertureless probe.In addition,reductive particle transportation on the surface of fiber probe is proposed to explain the cause of these probes.

  20. Characterization of near-field optical probes

    DEFF Research Database (Denmark)

    Vohnsen, Brian; Bozhevolnyi, Sergey I.

    1999-01-01

    Radiation and collection characteristics of four different near-field optical-fiber probes, namely, three uncoated probes and an aluminium-coated small-aperture probe, are investigated and compared. Their radiation properties are characterized by observation of light-induced topography changes...... in a photo-sensitive film illuminated with the probes, and it is confirmed that the radiated optical field is unambigiously confined only for the coated probe. Near-field optical imaging of a standing evanescent-wave pattern is used to compare the detection characteristics of the probes, and it is concluded...... that, for the imaging of optical-field intensity distributions containing predominantly evanescent-wave components, a sharp uncoated tip is the probe of choice. Complementary results obtained with optical phase-conjugation experiments with he uncoated probes are discussed in relation to the probe...

  1. Experiment on the phase congruency of distributed feedback optical fiber laser hydrophones%分布反馈光纤激光水听器相位一致性的测试方法

    Institute of Scientific and Technical Information of China (English)

    宋晓燕; 张文涛; 何俊; 李芳; 刘育梁

    2011-01-01

    在传统压电水听器相位一致性测试的基础上提出了分布反馈(DFB)光纤激光水听器相位一致性的测试方法,并搭建了测试系统.采用偏振无关的非平衡迈克尔逊干涉仪和归一化的相位载波(PGC)解调方案,解调出光纤激光水听器感受的水声信号,并与参考压电水听器作对比,使用高精度相位检测器将两信号转化为相位差信号:重复测量第二支光纤激光水听器:将两个相位差值作比较即可得到光纤激光水听器的相位一致性.实验证明了测试系统的稳定性;同时对光纤激光水听器的相位一致性进行了测试和分析,证明了光纤激光水听器具有很高的相位一致性.%A method of detecting the phase congruency of distributed feedback (DFB) optical fiber laser hydrophones was proposed based on detection system of traditional piezoelectric hydrophones, and the phase congruency detection system was set up.A polarization-insensitive unbalanced Michelson fiber interferometer was employed to transfer the frequency shifts to the phase shifts of the interferometer.After converting the output optical signal of the interferometer to electric signal, a normalized phase generated carrier (PGC) demodulation technique was used to demodulate the acoustic signal.Then the demodulated signal and the signal of the reference piezoelectric hydrophone were input into a high-resolution digital phase detector to get the phase difference.Repeat the above steps with another optical fiber laser hydrophone and compare the two results, the phase congruency between the two optical fiber laser hydrophones would be calculated.Corresponding experiments show the reliability of the phase congruency detection system and the high phase congruency between optical fiber laser hydrophones.

  2. Ultrathin lensed fiber-optic probe for optical coherence tomography.

    Science.gov (United States)

    Qiu, Y; Wang, Y; Belfield, K D; Liu, X

    2016-06-01

    We investigated and validated a novel method to develop ultrathin lensed fiber-optic (LFO) probes for optical coherence tomography (OCT) imaging. We made the LFO probe by attaching a segment of no core fiber (NCF) to the distal end of a single mode fiber (SMF) and generating a curved surface at the tip of the NCF using the electric arc of a fusion splicer. The novel fabrication approach enabled us to control the length of the NCF and the radius of the fiber lens independently. By strategically choosing these two parameters, the LFO probe could achieve a broad range of working distance and depth of focus for different OCT applications. A probe with 125μm diameter and lateral resolution up to 10μm was demonstrated. The low-cost, disposable and robust LFO probe is expected to have great potential for interstitial OCT imaging.

  3. Liquid crystal-based hydrophone arrays

    Science.gov (United States)

    Brodzeli, Zourab; Silvestri, Leonardo; Michie, Andrew; Chigrinov, Vladimir G.; Guo, Qi; Pozhidaev, Eugene P.; Kiselev, Alexei D.; Ladouceur, Francois

    2012-09-01

    We describe a fiber optic hydrophone array system that could be used for underwater acoustic surveillance applications (e.g. military, counter terrorist, and customs authorities in protecting ports and harbors), offshore production facilities or coastal approaches as well as various marine applications. In this paper, we propose a new approach to underwater sonar systems using the voltage-controlled liquid crystals and simple multiplexing method. The proposed method permits measurement of sound under water at multiple points along an optical fiber using the low cost components and standard single mode fiber, without complex interferometric measurement techniques, electronics or demodulation software.

  4. Lorentz-Force Hydrophone Characterization

    CERN Document Server

    Grasland-Mongrain, Pol; Gilles, Bruno; Poizat, Adrien; Chapelon, Jean-Yves; Lafon, Cyril

    2014-01-01

    A Lorentz-force hydrophone consists of a thin wire placed inside a magnetic field. When under the influence of an ultrasound pulse, the wire vibrates and an electrical signal is induced by the Lorentz force that is proportional to the pulse amplitude. In this study a compact prototype of such a hydrophone is introduced and characterized, and the hydrodynamic model previously developed is refined. It is shown that the wire tension has a negligible effect on the measurement of pressure. The frequency response of the hydrophone reaches 1 MHz for wires with a diameter ranging between 70 and 400 \\micro m. The hydrophone exhibits a directional response such that the signal amplitude differs by less than 3dB as the angle of the incident ultrasound pulse varies from -20$^o$ and +20$^o$. The linearity of the measured signal is confirmed across the 50 kPa to 10 MPa pressure range, and an excellent resistance to cavitation is observed. This hydrophone is of interest for high pressure ultrasound measurements including Hi...

  5. Single optical fiber probe for optogenetics

    Science.gov (United States)

    Falk, Ryan; Habibi, Mohammad; Pashaie, Ramin

    2012-03-01

    With the advent of optogenetics, all optical control and visualization of the activity of specific cell types is possible. We have developed a fiber optic based probe to control/visualize neuronal activity deep in the brain of awake behaving animals. In this design a thin multimode optical fiber serves as the head of the probe to be inserted into the brain. This fiber is used to deliver excitation/stimulation optical pulses and guide a sample of the emission signal back to a detector. The major trade off in the design of such a system is to decrease the size of the fiber and intensity of input light to minimize physical damage and to avoid photobleaching/phototoxicity but to keep the S/N reasonably high. Here the excitation light, and the associated emission signal, are frequency modulated. Then the output of the detector is passed through a time-lens which compresses the distributed energy of the emission signal and maximizes the instantaneous S/N. By measuring the statistics of the noise, the structure of the time lens can be designed to achieve the global optimum of S/N. Theoretically, the temporal resolution of the system is only limited by the time lens diffraction limit. By adding a second detector, we eliminated the effect of input light fluctuations, imperfection of the optical filters, and back-reflection of the excitation light. We have also designed fibers and micro mechanical assemblies for distributed delivery and detection of light.

  6. Creating and Probing Graphene Electron Optics with Local Scanning Probes

    Science.gov (United States)

    Stroscio, Joseph

    Ballistic propagation and the light-like dispersion of graphene charge carriers make graphene an attractive platform for optics-inspired graphene electronics where gate tunable potentials can control electron refraction and transmission. In analogy to optical wave propagation in lenses, mirrors and metamaterials, gate potentials can be used to create a negative index of refraction for Veselago lensing and Fabry-Pérot interferometers. In circular geometries, gate potentials can induce whispering gallery modes (WGM), similar to optical and acoustic whispering galleries albeit on a much smaller length scale. Klein scattering of Dirac carriers plays a central role in determining the coherent propagation of electron waves in these resonators. In this talk, I examine the probing of electron resonators in graphene confined by linear and circular gate potentials with the scanning tunneling microscope (STM). The tip in the STM tunnel junction serves both as a tunable local gate potential, and as a probe of the graphene states through tunneling spectroscopy. A combination of a back gate potential, Vg, and tip potential, Vb, creates and controls a circular pn junction that confines the WGM graphene states. The resonances are observed in two separate channels in the tunneling spectroscopy experiment: first, by directly tunneling into the state at the bias energy eVb, and, second, by tunneling from the resonance at the Fermi level as the state is gated by the tip potential. The second channel produces a fan-like set of WGM peaks, reminiscent of the fringes seen in planar geometries by transport measurements. The WGM resonances split in a small applied magnetic field, with a large energy splitting approaching the WGM spacing at 0.5 T. These results agree well with recent theory on Klein scattering in graphene electron resonators. This work is done in collaboration with Y. Zhao, J. Wyrick, F.D. Natterer, J. F. Rodriquez-Nieva, C. Lewandoswski, K. Watanabe, T. Taniguchi, N. B

  7. FBG Hydrophone: Theory and Experiment

    Institute of Scientific and Technical Information of China (English)

    Wen-Tao Zhang; Fang Li; Yu-Liang Liu

    2008-01-01

    A fiber Bragg grating (FBG) hydrophone with enhanced sensitivity is demonstrated. A novel piston-like diaphragm with a hard core fixed at the center is used as the sensing element. Theoretical analysis shows that the Young's modulus of the diaphragm and the radius of the hard core have significant effect on the pressure sensitivity. Experiments are carried out to test this effect and the performance of the hydrophone. The static measure-ment result is in good agreement with the theoretical result and an acoustic sensitivity of 7 nm/MPa has been achieved.

  8. Probing the Casimir force with optical tweezers

    CERN Document Server

    Ether, D S; Umrath, S; Martinez, D; Ayala, Y; Pontes, B; Araújo, G R de S; Frases, S; Ingold, G -L; Rosa, F S S; Viana, N B; Nussenzveig, H M; Neto, P A Maia

    2015-01-01

    We propose to use optical tweezers to probe the Casimir interaction between microspheres inside a liquid medium for geometric aspect ratios far beyond the validity of the widely employed proximity force approximation. This setup has the potential for revealing unprecedented features associated to the non-trivial role of the spherical curvatures. For a proof of concept, we measure femtonewton double layer forces between polystyrene microspheres at distances above $400$ nm by employing very soft optical tweezers, with stiffness of the order of fractions of a fN/nm. As a future application, we propose to tune the Casimir interaction between a metallic and a polystyrene microsphere in saline solution from attraction to repulsion by varying the salt concentration. With those materials, the screened Casimir interaction may have a larger magnitude than the unscreened one. This line of investigation has the potential for bringing together different fields including classical and quantum optics, statistical physics an...

  9. Probing the nano-bio interface with nanoplasmonic optical probes

    Science.gov (United States)

    Yu, X.; Wu, Linxi; Khanehzar, Ali; Feizpour, Amin; Xu, Fangda; Reinhard, Björn M.

    2014-08-01

    Noble metal nanoparticles have large cross-sections in both optical and electron microscopy and plasmon coupling between noble metal nanoparticles facilitate the characterization of subdiffraction limit separations through spectral analysis of the scattered light in Plasmon Coupling Microscopy (PCM). The size compatibility of noble metal nanoparticles together with the ability to encode specific functionality in a rational fashion by control of the nanoparticle surface makes noble metal nanoparticles unique probes for a broad range of biological processes. Recent applications of the technology include i.) characterization of cellular heterogeneity in nanomaterial uptake and processing through macrophages, ii.) testing the role of viral membrane lipids in mediating viral binding and trafficking, and iii.) characterizing the spatial organization of cancer biomarkers in plasma membranes. This paper reviews some of these applications and introduces the physical and material science principles underlying them. We will also introduce the use of membrane wrapped noble metal nanoparticles, which combine the superb photophysical properties of a nanoparticle core with the biological functionality of a membrane, as probes in PCM.

  10. A passive hydrophone for high-frequency application

    Energy Technology Data Exchange (ETDEWEB)

    Cuneo, Stefano [Istituto Nazionale di Fisica Nucleare, Via Dodecaneso 33, Genova 16146 (Italy)]. E-mail: stefano.cuneo@ge.infn.it; Plotnikov, A. [on leave from Moscow State University, 119992, Moscow (Russian Federation); Repetto, Luca [Dipartimento di Fisica dell' Universita di Genova, Via Dodecaneso 33, Genova 16146 (Italy); Anghinolfi, Marco [Istituto Nazionale di Fisica Nucleare, Via Dodecaneso 33, Genova 16146 (Italy)

    2006-11-15

    Passive, fiber-optics-based hydrophones are already used for marine acoustic positioning systems, oceanographic and geophysics research, as well as for military application. An existing concept has been optimized in order to increase device frequency bandwidth and operating depth, thus making the device attractive for new fields of application. A full-detailed design has been done and a prototype assembled to have an overview of all manufacturing issues. That hydrophone will be submitted to a full qualification test campaign, to validate the design approach in view of further optimization.

  11. Luminescent probes for optical in vivo imaging

    Science.gov (United States)

    Texier, Isabelle; Josserand, Veronique; Garanger, Elisabeth; Razkin, Jesus; Jin, Zhaohui; Dumy, Pascal; Favrot, Marie; Boturyn, Didier; Coll, Jean-Luc

    2005-04-01

    Going along with instrumental development for small animal fluorescence in vivo imaging, we are developing molecular fluorescent probes, especially for tumor targeting. Several criteria have to be taken into account for the optimization of the luminescent label. It should be adapted to the in vivo imaging optical conditions : red-shifted absorption and emission, limited overlap between absorption and emission for a good signal filtering, optimized luminescence quantum yield, limited photo-bleaching. Moreover, the whole probe should fulfill the biological requirements for in vivo labeling : adapted blood-time circulation, biological conditions compatibility, low toxicity. We here demonstrate the ability of the imaging fluorescence set-up developed in LETI to image the bio-distribution of molecular probes on short times after injection. Targeting with Cy5 labeled holo-transferrin of subcutaneous TS/Apc (angiogenic murine breast carcinoma model) or IGROV1 (human ovarian cancer) tumors was achieved. Differences in the kinetics of the protein uptake by the tumors were evidenced. IGROV1 internal metastatic nodes implanted in the peritoneal cavity could be detected in nude mice. However, targeted metastatic nodes in lung cancer could only be imaged after dissection of the mouse. These results validate our fluorescence imaging set-up and the use of Cy5 as a luminescent label. New fluorescent probes based on this dye and a molecular delivery template (the RAFT molecule) can thus be envisioned.

  12. Portable optical fiber probe for in vivo brain temperature measurements.

    Science.gov (United States)

    Musolino, Stefan; Schartner, Erik P; Tsiminis, Georgios; Salem, Abdallah; Monro, Tanya M; Hutchinson, Mark R

    2016-08-01

    This work reports on the development of an optical fiber based probe for in vivo measurements of brain temperature. By utilizing a thin layer of rare-earth doped tellurite glass on the tip of a conventional silica optical fiber a robust probe, suitable for long-term in vivo measurements of temperature can be fabricated. This probe can be interrogated using a portable optical measurement setup, allowing for measurements to be performed outside of standard optical laboratories.

  13. Physically Damped Noise Canceling Hydrophone

    Science.gov (United States)

    2016-06-24

    300075 1 of 10 PHYSICALLY DAMPED NOISE CANCELING HYDROPHONE STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be...transducer with an electromechanical driver comprising a plurality of single crystal piezoelectric elements joined to an inner surface and arranged to form...an electromechanical stack assembly. Each single crystal piezoelectric element has a surface, an opposite surface, and a Attorney Docket No

  14. Design considerations for miniaturized optical neural probes

    Science.gov (United States)

    Rudmann, Linda; Ordonez, Juan S.; Stieglitz, Thomas

    2016-03-01

    Neural probes are designed to selectively record from or stimulate nerve cells. In optogenetics it is desirable to build miniaturized and long-term stable optical neural probes, in which the light sources can be directly and chronically implanted into the animals to allow free movement and behavior. Because of the size and the beam shape of the available light sources, it is difficult to target single cells as well as spatially localized networks. We therefore investigated design considerations for packages, which encapsulate the light source hermetically and have integrated hemispherical lens structures that enable to focus the light onto the desired region, by optical simulations. Integration of a biconvex lens into the package lid (diameter = 300 μm, material: silicon carbide) increased the averaged absolute irradiance ηA by 298 % compared to a system without a lens and had a spot size of around 120 μm. Solely integrating a plano-convex lens (same diameter and material) results in an ηA of up to 227 %.

  15. FO hydrophone with hydrostatic pressure compensation: comparative experiment with a conventional piezo hydrophone

    NARCIS (Netherlands)

    Cheng, L.K.; Bruijn, D. de

    1998-01-01

    This paper presents the performance of a TPD FO hydrophone with hydrostatic pressure compensation. In particularly a comparison with a conventional piezo hydrophone system is discussed. ©2003 Copyright SPIE

  16. 高性能三维全保偏光纤矢量水听器研制%Development of three-component all polarization-maintaining optical fiber vector hydrophone

    Institute of Scientific and Technical Information of China (English)

    王建飞; 罗洪; 熊水东; 孟洲; 胡永明

    2011-01-01

    研制了高性能的三维光纤矢量听水器,采用全保偏光纤结构消除偏振不稳定性影响、光频调制相位载波(PGc)技术消除随机相位漂移,实现了探测单元的全光化。优化结构设计,采用薄壁空心刚性圆柱结构作为弹性柱体,大大拓展了光纤矢量水听器的工作频带,同时保证了水听器探测灵敏度。经权威机构检测,该光纤矢量水听器的工作频带为20~2000Hz,加速度灵敏度为33dB,工作带宽内加速度灵敏度起伏小于1.4dB,1000Hz处声压灵敏度为-155dB,具有良好的余弦指向性,指向性指数大于45dB,最大轴向不对称性小于0.4dB。%This paper reports a novel all polarization-maintaining optical fiber vector hydrophone. The all polarization-maintaining optical fiber interferometer structure can prevent signal fading due to random changes in the polarization state of the guided beams. The signal fading caused by random phase-shift in the interferometer is eliminated by the phase generated carrier(PGC) technology. The sensor is all-opti cal, which is convenient to be applied for long distance detection and transmission. The sensitivity and frequeny band of the sensor are enhanced by optimizing the structure. The acceleration sensitivity reaches 33 dB and the fluctuation is less than 1 dB in frequency band of 20--2 000 Hz. The phase sensitivity is --155 dB at 1000 Hz. The optical vector hydrophone has an excellent directivity. The maximum asymetric index is less than 0. 4 dB and the directivity index is greater than 45 dB.

  17. FABRICATION AND APPLICATION OF NEARFIELD OPTICAL FIBRE PROBE

    Institute of Scientific and Technical Information of China (English)

    SUN JIA-LIN; XU JIAN-HUA; TIAN GUANG-YAN; GUo JI-HUA; ZHAO JUN; XIE AI-FANG; ZHANG ZE-BO

    2001-01-01

    In this paper, the fabrication of a large cone angle near-field optical fibre probe, using the two-step chemical etching method and bent probe, is introduced, and the controlling parameters of the coated Cr-Al film at the probe tip are presented. The scanning electron microscopy images display that the tip diameter of the uncoated large cone angle fibre probe obtained is less than 50nm, the cone angle over 90°, and the diameter of light aperture at the coated probe tip is less than 100nm. The measured results of the optical transmission efficiency for various probe tips show that the uncoated straight optical fibre probe, film-coated straight probe and film-coated bent probe are 3×10-1, 2×10-3, and l×10-4 times that of the flat fibre probe, respectively. In addition, the force images and near-field optical images of a standard sample are acquired using a large cone angle and film-coated bent probe.

  18. All-optical photoacoustic imaging system using fiber ultrasound probe and hollow optical fiber bundle.

    Science.gov (United States)

    Miida, Yusuke; Matsuura, Yuji

    2013-09-23

    An all-optical 3D photoacoustic imaging probe that consists of an optical fiber probe for ultrasound detection and a bundle of hollow optical fibers for excitation of photoacoustic waves was developed. The fiber probe for ultrasound is based on a single-mode optical fiber with a thin polymer film attached to the output end surface that works as a Fabry Perot etalon. The input end of the hollow fiber bundle is aligned so that each fiber in the bundle is sequentially excited. A thin and flexible probe can be obtained because the probe system does not have a scanning mechanism at the distal end.

  19. Optical characterication of probes for photon scanning tunnelling microscopy

    DEFF Research Database (Denmark)

    Vohnsen, Brian; Bozhevolnyi, Sergey I.

    1999-01-01

    The photon scanning tunnelling microscope is a well-established member of the family of scanning near-field optical microscopes used for optical imaging at the sub-wavelength scale. The quality of the probes, typically pointed uncoated optical fibres, used is however difficult to evaluate...

  20. A virtual optical probe based on evanescent wave interference

    Institute of Scientific and Technical Information of China (English)

    孙利群; 王佳; 洪涛; 田芊

    2002-01-01

    A virtual probe is a novel immaterial tip based on the near-field evanescent wave interference and small aperture diffraction, which can be used in near-field high-density optical data storage, nano-lithography, near-field optical imaging and spectral detection, near-field optical manipulation of nano-scale specimen, etc. In this paper, the formation mechanism of the virtual probe is analysed, the evanescent wave interference discussed theoretically, andthe sidelobe suppression by small aperture is simulated by the three-dimensional finite-difference time-domain method The simulation results of the optical distribution of the near-field virtual probe reveal that the transmission efficiencyof the virtual probe is 102-104 times higher than that of the nano-aperture metal-coated fibre probe widely used in near-field optical systems. The full width at half maximum of the peak, in other words, the size of virtual probe, is constant whatever the distance in a certain range so that the critical nano-separation control in the near-field system can be relaxed. We give an example of the application of the virtual probe in ultrahigh-density optical data storage.

  1. Near-Field Optical Microscopy and Spectroscopy with Pointed Probes

    Science.gov (United States)

    2006-01-01

    metal nanostructure can be viewed as an optical antenna . Of course, the efficiency depends on the material composition and the geometry of the...nanostructure. A simple form of optical antenna is a single ellipsoidal particle. This particle ex- hibits a distinct resonance for which the field...Grober RD, Schoelkopf RJ, Prober DE. 1997. Optical antenna : towards a unity efficiency near-field optical probe. Appl. Phys. Lett. 70:1354 54. Farahani

  2. Magnetic field concentrator for probing optical magnetic metamaterials.

    Science.gov (United States)

    Antosiewicz, Tomasz J; Wróbel, Piotr; Szoplik, Tomasz

    2010-12-06

    Development of all dielectric and plasmonic metamaterials with a tunable optical frequency magnetic response creates a need for new inspection techniques. We propose a method of measuring magnetic responses of such metamaterials within a wide range of optical frequencies with a single probe. A tapered fiber probe with a radially corrugated metal coating concentrates azimuthally polarized light in the near-field into a subwavelength spot the longitudinal magnetic field component which is much stronger than the perpendicular electric one. The active probe may be used in a future scanning near-field magnetic microscope for studies of magnetic responses of subwavelength elementary cells of metamaterials.

  3. Polymeric Piezoelectric Transducers for Hydrophone Applications

    Directory of Open Access Journals (Sweden)

    D. K. Kharat

    2007-01-01

    Full Text Available Conventional ceramic piezoelectric materials have been used in hydrophones for sonarapplications since 1940's. In the last few years since the discovery of polymeric piezoelectrichydrophones, the technology has matured, applications have emerged in extraordinary number ofcases such as underwater navigation, biomedical applications, biomimetics, etc. Hydrophones areused underwater at high hydrostatic pressures. In the presence of hydrostatic pressures, theanisotropic piezoelectric response of ceramic materials is such that it has poor hydrophone performancecharacteristics whereas polymeric piezoelectric materials show enough hydrostatic piezoelectriccoefficients. Moreover, piezoelectric polymers have low acoustic impedance, which is only 2-6 timethat of water, whereas in piezoelectric ceramics, it is typically 11-time greater than that of water. Aclose impedance match permits efficient transduction of acoustic signals in water and tissues. Newlydeveloped hydrostatic-mode polyvinylidene flouride (PVDF hydrophones use a pressure-releasesystem to achieve improved sensitivity. Recently, voided PVDF materials have been used for makinghydrophones having higher sensitivity and figure of merit than unvoided PVDF materials.

  4. Optical fiber hydrophone demodulation system based on parameter estimation method%基于参数估计的光纤水听器解调系统研究

    Institute of Scientific and Technical Information of China (English)

    施清平; 王凯; 王利威; 张华勇; 田芊

    2011-01-01

    An optical fiber hydrophone demodulation system based on division lookup table (DLT) phase generated carrier ( PGC) and progressive parameter estimation method is implemented and its engineering application is stud-ied. The principle of the parameter extraction method is described in detail theoretically and its stability and effec-tiveness are analyzed experimentally. Experimental tests show that the extraction accuracy of fundamental/second-harmonic signal phase delay is better than 5% . The estimation accuracies of intensity, accompanying amplitude modulation and phase correction factor are 0. 5% , 2. 5% and 5% , respectively, which meet the requirements of practical engineering application. The demodulation result of this new optical fiber system has small harmonic distor-tion and its linearity is equivalent to that of standard piezoelectric hydrophone. The background noise of the demodu-lated system reaches -90 dB/Hz@ 100 Hz and -95 dB/Hz@ 1 kHz. The variance of Signal to Noise and Distortion ratio (SINAD) is less than 1 dB and the variance of Total Harmonic Distortion ratio (THD) is about 2 dB during 10 hour continuous experiment. These experimental results confirm that this system has good stability, linearity and noise characteristic, which meet engineering application requirements.%研究并实现了可工程应用的光纤水听器解调系统,采用相除查找表的PGC解调方案和逐步参数估计的参数提取方法.从理论上详细阐述了参数提取方法原理,并从实验上分析了该方法的稳定性和有效性.实验测试表明1倍频/2倍频相位延迟的提取精度优于5%.光强、伴生调幅和角度修正因子的估算精度分别达到0.5%,2.5%和5%,能够满足实际工程应用要求.所研制的光纤水听器解调系统解调结果谐波分量较少,失真小.相比于标准压电水昕器系统,具有很好的线性度.解调系统噪声本底达到- 90 dB/Hz@ 100 Hz和- 95 dB/Hz@1 kHz.10 h

  5. Raman imaging of biofilms using gold sputtered fiber optic probes

    Science.gov (United States)

    Christopher, Christina Grace Charlet; Manoharan, Hariharan; Subrahmanyam, Aryasomayajula; Sai, V. V. Raghavendra

    2016-12-01

    In this work we report characterization of bacterial biofilm using gold sputtered optical fiber probe as substrates for confocal Raman spectroscopy measurements. The chemical composition and the heterogeneity of biofilms in the extracellular polymeric substances (EPS) was evaluated. The spatial distribution of bacterial biofilm on the substrates during their growth phase was studied using Raman imaging. Further, the influence of substrate's surface on bacterial adhesion was investigated by studying growth of biofilms on surfaces with hydrophilic and hydrophobic coatings. This study validates the use of gold sputtered optical fiber probes as SERS substrates in confocal microscopic configuration to identify and characterize clinically relevant biofilms.

  6. Optical tweezer for probing erythrocyte membrane deformability

    CERN Document Server

    Khan, Manas; Sood, A K; 10.1063/1.3272269

    2010-01-01

    We report that the average rotation speed of optically trapped crenated erythrocytes is direct signature of their membrane deformability. When placed in hypertonic buffer, discocytic erythrocytes are subjected to crenation. The deformation of cells brings in chirality and asymmetry in shape that make them rotate under the scattering force of a linearly polarized optical trap. A change in the deformability of the erythrocytes, due to any internal or environmental factor, affects the rotation speed of the trapped crenated cells. Here we show how the increment in erythrocyte membrane rigidity with adsorption of $Ca^{++}$ ions can be exhibited through this approach.

  7. Probing exoplanet clouds with optical phase curves.

    Science.gov (United States)

    Muñoz, Antonio García; Isaak, Kate G

    2015-11-01

    Kepler-7b is to date the only exoplanet for which clouds have been inferred from the optical phase curve--from visible-wavelength whole-disk brightness measurements as a function of orbital phase. Added to this, the fact that the phase curve appears dominated by reflected starlight makes this close-in giant planet a unique study case. Here we investigate the information on coverage and optical properties of the planet clouds contained in the measured phase curve. We generate cloud maps of Kepler-7b and use a multiple-scattering approach to create synthetic phase curves, thus connecting postulated clouds with measurements. We show that optical phase curves can help constrain the composition and size of the cloud particles. Indeed, model fitting for Kepler-7b requires poorly absorbing particles that scatter with low-to-moderate anisotropic efficiency, conclusions consistent with condensates of silicates, perovskite, and silica of submicron radii. We also show that we are limited in our ability to pin down the extent and location of the clouds. These considerations are relevant to the interpretation of optical phase curves with general circulation models. Finally, we estimate that the spherical albedo of Kepler-7b over the Kepler passband is in the range 0.4-0.5.

  8. Probing exoplanet clouds with optical phase curves

    CERN Document Server

    Munoz, A Garcia

    2015-01-01

    Kepler-7b is to date the only exoplanet for which clouds have been inferred from the optical phase curve -- from visible-wavelength whole-disk brightness measurements as a function of orbital phase. Added to this, the fact that the phase curve appears dominated by reflected starlight makes this close-in giant planet a unique study case. Here we investigate the information on coverage and optical properties of the planet clouds contained in the measured phase curve. We generate cloud maps of Kepler-7b and use a multiple-scattering approach to create synthetic phase curves, thus connecting postulated clouds with measurements. We show that optical phase curves can help constrain the composition and size of the cloud particles. Indeed, model fitting for Kepler-7b requires poorly absorbing particles that scatter with low-to-moderate anisotropic efficiency, conclusions consistent with condensates of silicates, perovskite, and silica of submicron radii. We also show that we are limited in our ability to pin down the...

  9. Effects of probe geometry on transscleral diffuse optical spectroscopy.

    Science.gov (United States)

    Svenmarker, Pontus; Xu, Can T; Andersson-Engels, Stefan; Krohn, Jørgen

    2011-11-01

    The purpose of this study was to investigate how the geometry of a fiber optic probe affects the transmission and reflection of light through the scleral eye wall. Two geometrical parameters of the fiber probe were investigated: the source-detector distance and the fiber protrusion, i.e. the length of the fiber extending from the flat surface of the fiber probe. For optimization of the fiber optic probe geometry, fluorescence stained choroidal tumor phantoms in ex vivo porcine eyes were measured with both diffuse reflectance- and laser-induced fluorescence spectroscopy. The strength of the fluorescence signal compared to the excitation signal was used as a measure for optimization. Intraocular pressure (IOP) and temperature were monitored to assess the impact of the probe on the eye. For visualizing any possible damage caused by the probe, the scleral surface was imaged with scanning electron microscopy after completion of the spectroscopic measurements. A source-detector distance of 5 mm with zero fiber protrusion was considered optimal in terms of spectroscopic contrast, however, a slight fiber protrusion of 0.5 mm is argued to be advantageous for clinical measurements. The study further indicates that transscleral spectroscopy can be safely performed in human eyes under in vivo conditions, without leading to an unacceptable IOP elevation, a significant rise in tissue temperature, or any visible damage to the scleral surface.

  10. Demonstration of a Fiber Optic Regression Probe

    Science.gov (United States)

    Korman, Valentin; Polzin, Kurt A.

    2010-01-01

    The capability to provide localized, real-time monitoring of material regression rates in various applications has the potential to provide a new stream of data for development testing of various components and systems, as well as serving as a monitoring tool in flight applications. These applications include, but are not limited to, the regression of a combusting solid fuel surface, the ablation of the throat in a chemical rocket or the heat shield of an aeroshell, and the monitoring of erosion in long-life plasma thrusters. The rate of regression in the first application is very fast, while the second and third are increasingly slower. A recent fundamental sensor development effort has led to a novel regression, erosion, and ablation sensor technology (REAST). The REAST sensor allows for measurement of real-time surface erosion rates at a discrete surface location. The sensor is optical, using two different, co-located fiber-optics to perform the regression measurement. The disparate optical transmission properties of the two fiber-optics makes it possible to measure the regression rate by monitoring the relative light attenuation through the fibers. As the fibers regress along with the parent material in which they are embedded, the relative light intensities through the two fibers changes, providing a measure of the regression rate. The optical nature of the system makes it relatively easy to use in a variety of harsh, high temperature environments, and it is also unaffected by the presence of electric and magnetic fields. In addition, the sensor could be used to perform optical spectroscopy on the light emitted by a process and collected by fibers, giving localized measurements of various properties. The capability to perform an in-situ measurement of material regression rates is useful in addressing a variety of physical issues in various applications. An in-situ measurement allows for real-time data regarding the erosion rates, providing a quick method for

  11. Hydraulic test for evaluation of hydrophone VSP

    Energy Technology Data Exchange (ETDEWEB)

    Yabuuchi, Satoshi; Koide, Kaoru [Power Reactor and Nuclear Fuel Development Corp., Toki, Gifu (Japan). Tono Geoscience Center

    1997-12-01

    This hydraulic test was carried out at the test site of Tono Geoscience Center, Mizunami-shi, Gifu Pref. in order to evaluate the reliability of the hydraulic conductivity estimated from hydrophone VSP experiment. From March to April 1997, we carried out measurements of pore-water pressure at five depths and permeability tests at seven depths down to G.L.-300m, within a borehole drilled in granitic rock. We compared the results of hydraulic test with hydrophone VSP experiment on condition that a single open fracture existed, and we obtained two notable results. First, for the granitic rock at which a single open fracture was found by BTV and also detected by hydrophone VSP experiment, the hydraulic conductivity was 1.54 x 10{sup -7} cm/sec, while for the same granitic rock at which another single open fracture was found by BTV but not detected by hydrophone VSP experiment, the hydraulic conductivity was less than 6 x 10{sup -10} cm/sec. Second, we converted the hydraulic conductivity of 1.54 x 10{sup -7} cm/sec which was obtained in a hydraulic test section of length 2.5 m into an equivalent value for a single open fracture of width 1 mm. The converted value (3.8 x 10{sup -4} cm/sec) was similar to the hydraulic conductivity estimated from hydrophone VSP experiment. In conclusion, the hydraulic test result shows that hydrophone VSP is useful to estimate an approximate hydraulic conductivity of a single open fracture. (author)

  12. Developing fibre optic Raman probes for applications in clinical spectroscopy.

    Science.gov (United States)

    Stevens, Oliver; Iping Petterson, Ingeborg E; Day, John C C; Stone, Nick

    2016-04-07

    Raman spectroscopy has been shown by various groups over the last two decades to have significant capability in discriminating disease states in bodily fluids, cells and tissues. Recent development in instrumentation, optics and manufacturing approaches has facilitated the design and demonstration of various novel in vivo probes, which have applicability for myriad of applications. This review focusses on key considerations and recommendations for application specific clinical Raman probe design and construction. Raman probes can be utilised as clinical tools able to provide rapid, non-invasive, real-time molecular analysis of disease specific changes in tissues. Clearly the target tissue location, the significance of spectral changes with disease and the possible access routes to the region of interest will vary for each clinical application considered. This review provides insight into design and construction considerations, including suitable probe designs and manufacturing materials compatible with Raman spectroscopy.

  13. Microball lens integrated fiber probe for optical frequency domain imaging

    Institute of Scientific and Technical Information of China (English)

    Jae-Ho Han; J.U.Kang

    2011-01-01

    An integrated microball lens fiber catheter probe is demonstrated, which has better lateral resolution and longer working distance than a corresponding bare fiber probe with diverging beam for Fourier domain optical coherence tomography (FDOCT). Simulation results are shown to gain the effect of the distance between the microball lens and the bare fiber to the focusing plane and beam width. The freedom of modifying the working distance and lateral resolution is shown. This is achieved by changing the gap distance between the single-mode fiber and the microball lens within the packaged surgical needle catheter without using an additional beam expander having a fixed length. The probe successfully acquired cross-sectional images of ocular tissues from an animal sample with the proposed miniaturized imaging probe.%@@ An integrated microball lens fiber catheter probe is demonstrated,which has better lateral resolution and longer working distance than a corresponding bare fiber probe with diverging beam for Fourier domain optical coherence tomography(FDOCT).Simulation results are shown to gain the effect of the distance between the microball lens and the bare fiber to the focusing plane and beam width.The freedom of modifying the working distance and lateral resolution is shown.This is achieved by changing the gap distance between the single-mode fiber and the microball lens within the packaged surgical needle catheter without using an additional beam expander having a fixed length.The probe successfully acquired crosssectional images of ocular tissues from an animal sample with the proposed miniaturized imaging probe.

  14. Optically probing torsional superelasticity in spider silks

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P. [Department of Physical Sciences, IISER Mohali, Sector 81, Manauli, Mohali 140306 (India)

    2013-11-11

    We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 10{sup 2−3} rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices.

  15. Optically probing torsional superelasticity in spider silks

    Science.gov (United States)

    Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P.

    2013-11-01

    We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 102-3 rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices.

  16. Screening far red probes for use on optical biochip devices

    Science.gov (United States)

    Njoh, Kerenza L.; Patterson, Laurence H.; Pors, Klaus; Zloh, Mire; Ameer-Beg, Simon; Summers, Huw; Matthews, Daniel; Errington, Rachel J.; Smith, Paul J.

    2006-02-01

    In situ spectral analysis can be used to understand the targeting and interaction of agents in cellular compartments. A range of novel red excitable fluorescent probes, related to the anthraquinone family of anti-cancer agents, were designed for their DNA affinic properties and their ability to enter and penetrate living cells. We report on the spectral features of these probes, both in solution and bound within intact cells, to identify unique fluorescent signatures that exploit their use in bioassays on optical biochip devices. The probes demonstrated red shifted emission spectra and increased 2 photon lifetime, with minimal fluorescent enhancement, upon binding to DNA. Spectral confocal laser scanning microscopy revealed complex emission profiles representing the bound (nuclear) and unbound (cytoplasmic) fractions of the DNA probes within live interphase, mitotic and apoptotic cells. Analysis of the emission peaks encoded the spectra to provide cell compartment recognition and profiles for cells in different cell states. Sampling the entire emission spectra of these probes for cell locating, even in the presence of unbound molecules, provides good signal-to-noise in biochip devices. Furthermore, by sampling the fluorescence output at specific spectral windows we can obtain high spatial information without imaging. The technological challenge is to integrate these fluorophores and appropriate detection capacity onto an optical biochip platform with microfluidic systems for cell handling.

  17. Handheld probes and galvanometer scanning for optical coherence tomography

    Science.gov (United States)

    Duma, V.-F.; Dobre, G.; Demian, D.; Cernat, R.; Sinescu, C.; Topala, F. I.; Negrutiu, M. L.; Hutiu, Gh.; Bradu, A.; Rolland, J. P.; Podoleanu, A. G.

    2015-09-01

    As part of the ongoing effort of the biomedical imaging community to move Optical Coherence Tomography (OCT) systems from the lab to the clinical environment and produce OCT systems appropriate for multiple types of investigations in a medical department, handheld probes equipped with different types of scanners need to be developed. These allow different areas of a patient's body to be investigated using OCT with the same system and even without changing the patient's position. This paper reviews first the state of the art regarding OCT handheld probes. Novel probes with a uni-dimensional (1D) galvanometer-based scanner (GS) developed in our groups are presented. Their advantages and limitations are discussed. Aspects regarding the use of galvoscanners with regard to Micro-Electro- Mechanical Systems (MEMS) are pointed out, in relationship with our studies on optimal scanning functions of galvanometer devices in OCT. These scanning functions are briefly discussed with regard to their main parameters: profile, theoretical duty cycle, scan frequency, and scan amplitude. The optical design of the galvoscanner and refractive optics combination in the probe head, optimized for various applications, is considered. Perspectives of the field are pointed out in the final part of the paper.

  18. Probing beyond the laser coherence time in optical clock comparisons

    Science.gov (United States)

    Hume, David B.; Leibrandt, David R.

    2016-03-01

    We develop differential measurement protocols that circumvent the laser noise limit in the stability of optical clock comparisons by synchronous probing of two clocks using phase-locked local oscillators. This allows for probe times longer than the laser coherence time, avoids the Dick effect, and supports Heisenberg-limited measurement precision. We present protocols for such frequency comparisons and develop numerical simulations of the protocols with realistic noise sources. These methods provide a route to reduce frequency ratio measurement durations by more than an order of magnitude.

  19. Magnetic Force Between Magnetic Nano Probes at Optical Frequency

    CERN Document Server

    Guclu, Caner; Capolino, Filippo

    2014-01-01

    Magnetic force microscopy based on the interaction of static magnetic materials was demonstrated in the past with resolutions in the order of nanometers. Measurement techniques based on forces between electric dipoles oscillating at optical frequencies have been also demonstrated leading to the standard operation of the scanning force microscope (SFM). However the investigations of a SFM based on the magnetic force generated by magnetic dipole moments oscillating at optical frequencies has not been tackled yet. With this goal in mind we establish a theoretical model towards observable magnetic force interaction between two magnetically polarizable nanoparticles at optical frequency and show such a force to be in the order of piconewtons which could be in principle detected by conventional microscopy techniques. Two possible principles for conceiving magnetically polarizable nano probes able to generate strong magnetic dipoles at optical frequency are investigated based on silicon nanoparticles and on clusters...

  20. Probing biological light-harvesting phenomena by optical cavities

    CERN Document Server

    Caruso, Filippo; Solano, Enrique; Huelga, Susana F; Aspuru-Guzik, Alán; Plenio, Martin B

    2011-01-01

    We propose a driven optical cavity quantum electrodynamics (QED) set up aimed at directly probing energy transport dynamics in photosynthetic biomolecules. We show that detailed information concerning energy transfer paths and delocalization of exciton states can be inferred (and exciton energies estimated) from the statistical properties of the emitted photons. This approach provides us with a novel spectroscopic tool for the interrogation of biological systems in terms of quantum optical phenomena which have been usually studied for atomic or solid-state systems, e.g. trapped atoms and semiconductor quantum dots.

  1. Advancement of Miniature Optic Gas Sensor (MOGS) Probe Technology

    Science.gov (United States)

    Chullen, Cinda

    2015-01-01

    Advancement of Miniature Optic Gas Sensor (MOGS) Probe Technology" project will investigate newly developed optic gas sensors delivered from a Small Business Innovative Research (SBIR) Phase II effort. A ventilation test rig will be designed and fabricated to test the sensors while integrated with a Suited Manikin Test Apparatus (SMTA). Once the sensors are integrated, a series of test points will be completed to verify that the sensors can withstand Advanced Suit Portable Life Support System (PLSS) environments and associated human metabolic profiles for changes in pressure and levels of Oxygen (ppO2), carbon dioxide (ppCO2), and humidity (ppH2O).

  2. Trapped ions in optical lattices for probing oscillator chain models

    CERN Document Server

    Pruttivarasin, Thaned; Talukdar, Ishan; Kreuter, Axel; Haeffner, Hartmut

    2011-01-01

    We show that a chain of trapped ions embedded in microtraps generated by an optical lattice can be used to study oscillator models related to dry friction and energy transport. Numerical calculations with realistic experimental parameters demonstrate that both static and dynamic properties of the ion chain change significantly as the optical lattice power is varied. Finally, we lay out an experimental scheme to use the spin degree of freedom to probe the phase space structure and quantum critical behavior of the ion chain.

  3. Processing of Graphene combining Optical Detection and Scanning Probe Lithography

    Directory of Open Access Journals (Sweden)

    Zimmermann Sören

    2015-01-01

    Full Text Available This paper presents an experimental setup tailored for robotic processing of graphene with in-situ vision based control. A robust graphene detection approach is presented applying multiple image processing operations of the visual feedback provided by a high-resolution light microscope. Detected graphene flakes can be modified using a scanning probe based lithographical process that is directly linked to the in-situ optical images. The results of this process are discussed with respect to further application scenarios.

  4. Lensed fiber probes designed as an alternative to bulk probes in optical coherence tomography.

    Science.gov (United States)

    Ryu, Seon Young; Choi, Hae Young; Na, Jihoon; Choi, Woo June; Lee, Byeong Ha

    2008-04-01

    We demonstrate a compact all-fiber sampling probe for an optical coherence tomography (OCT) system. By forming a focusing lens directly on the tip of an optical fiber, a compact sampling probe could be implemented. To simultaneously achieve a sufficiently long working distance and a good lateral resolution, we employed a large-mode area photonic crystal fiber (PCF) and a coreless silica fiber (CSF) of the same diameters. A working distance of up to 1270 microm, a 3 dB distance range of 2210 microm, and a transverse resolution of 14.2 microm were achieved with the implemented PCF lensed fiber; these values are comparable to those obtainable with a conventional objective lens having an NA of 0.25 (10 x). The performance of the OCT system equipped with the proposed PCF lensed fiber is presented by showing the OCT images of a rat finger as a biological sample and a pearl as an in-depth sample.

  5. Fibre laser hydrophones for cosmic ray particle detection

    CERN Document Server

    Buis, E J; Nieuwland, R A; Toet, P M

    2013-01-01

    The detection of ultra high energetic cosmic neutrinos provides a unique means to search for extragalactic sources that accelerate particles to extreme energies. It allows to study the neutrino component of the GZK cut-off in the cosmic ray energy spectrum and the search for neutrinos beyond this limit. Due to low expected flux and small interaction cross-section of neutrinos with matter large experimental set-ups are needed to conduct this type of research. Acoustic detection of cosmic rays may provide a means for the detection of ultra-high energetic neutrinos. Using relative low absorption of sound in water, large experimental set-ups in the deep sea are possible that are able to detect these most rare events, but it requires highly sensitive hydrophones as the thermo-acoustic pulse originating from a particle shower in water has a typical amplitude as low as a mPa. It has been shown in characterisation measurements that the fibre optic hydrophone technology as designed and realised at TNO provides the req...

  6. Optical injection probing of single ZnO tetrapod lasers

    Energy Technology Data Exchange (ETDEWEB)

    Szarko, Jodi M.; Song, Jae Kyu; Blackledge, Charles Wesley; Swart, Ingmar; Leone, Stephen R.; Li, Shihong; Zhao, Yiping

    2004-11-23

    The properties of zinc oxide (ZnO) nanotetrapod lasers are characterized by a novel ultrafast two-color pump/stimulated emission probe technique. Single legs of tetrapod species are isolated by a microscope objective, pumped by 267 nm pulses, and subjected to a time-delayed 400 nm optical injection pulse, which permits investigation of the ultrafast carrier dynamics in the nanosize materials. With the optical injection pulse included, a large increase in the stimulated emission at 400 nm occurs, which partially depletes the carriers at this wavelength and competes with the normal 390 nm lasing. At the 390 nm lasing wavelengths, the optical injection causes a decrease in the stimulated emission due to the energetic redistribution of the excited carrier depletion, which occurs considerably within the time scale of the subpicosecond duration of the injection pulse. The effects of the optical injection on the spectral gain are employed to probe the lasing dynamics, which shows that the full width at half maximum of the lasing time is 3 ps.

  7. Calibration of miniature medical ultrasonic hydrophones for frequencies in the range 100 to 500 kHz using an ultrasonically absorbing waveguide.

    Science.gov (United States)

    Rajagopal, Srinath; Zeqiri, Bajram; Gélat, Pierre N

    2014-05-01

    Enhancements to the existing primary standard optical interferometer and narrowband tone-burst comparison calibration methods for miniature medical ultrasonic hydrophones of the membrane type over the frequency range 100 to 500 kHz are described. Improvements were realized through application of an ultrasonically absorbing waveguide made of a low-frequency-absorbing tile used in sonar applications which narrows the spatial extent of the broad acoustic field. The waveguide was employed in conjunction with a sonar multilayered polyvinylidene difluoride (PVDF) hydrophone used as a transmitting transducer covering a frequency range of 100 kHz to 1 MHz. The acoustic field emanating from the ultrasonically absorbing waveguide reduced the significance of diffracted acoustic waves from the membrane hydrophone ring and the consequent interference of this wave with the direct acoustic wave received by the active element of the hydrophone during calibration. Four membrane hydrophone make/ models with ring sizes (defined as the inner diameter of the annular mounting ring of the hydrophone) in the range 50 to 100 mm were employed along with a needle hydrophone. A reference membrane hydrophone, calibrated using the NPL primary standard optical interferometer in combination with the ultrasonically absorbing waveguide, was subsequently used to calibrate the other four hydrophones by comparison, again using the ultrasonically absorbing waveguide. In comparison to existing methods, the use of the ultrasonically absorbing waveguide enabled the low-frequency calibration limit of a membrane hydrophone with a ring diameter of 50 mm to be reduced from 400 kHz to 200 kHz.

  8. Micromachined fiber optic Fabry-Perot underwater acoustic probe

    Science.gov (United States)

    Wang, Fuyin; Shao, Zhengzheng; Hu, Zhengliang; Luo, Hong; Xie, Jiehui; Hu, Yongming

    2014-08-01

    One of the most important branches in the development trend of the traditional fiber optic physical sensor is the miniaturization of sensor structure. Miniature fiber optic sensor can realize point measurement, and then to develop sensor networks to achieve quasi-distributed or distributed sensing as well as line measurement to area monitoring, which will greatly extend the application area of fiber optic sensors. The development of MEMS technology brings a light path to address the problems brought by the procedure of sensor miniaturization. Sensors manufactured by MEMS technology possess the advantages of small volume, light weight, easy fabricated and low cost. In this paper, a fiber optic extrinsic Fabry-Perot interferometric underwater acoustic probe utilizing micromachined diaphragm collaborated with fiber optic technology and MEMS technology has been designed and implemented to actualize underwater acoustic sensing. Diaphragm with central embossment, where the embossment is used to anti-hydrostatic pressure which would largely deflect the diaphragm that induce interferometric fringe fading, has been made by double-sided etching of silicon on insulator. By bonding the acoustic-sensitive diaphragm as well as a cleaved fiber end in ferrule with an outer sleeve, an extrinsic Fabry-Perot interferometer has been constructed. The sensor has been interrogated by quadrature-point control method and tested in field-stable acoustic standing wave tube. Results have been shown that the recovered signal detected by the sensor coincided well with the corresponding transmitted signal and the sensitivity response was flat in frequency range from 10 Hz to 2kHz with the value about -154.6 dB re. 1/μPa. It has been manifest that the designed sensor could be used as an underwater acoustic probe.

  9. Brighter near-field optical probes by means of improving the optical destruction threshold.

    Science.gov (United States)

    Stöckle, R M; Schaller, N; Deckert, V; Fokas, C; Zenobi, R

    1999-01-01

    The optical destruction thresholds of conventionally etched and tube-etched near-field optical probes were measured. One of the main advantages of tube-etched tips is their smooth glass surface after taper formation. Presumably for this reason, a destruction limit of over 120 microJ was obtained, almost twice as large as that of the rougher, conventionally etched fibre probes. The use of additional adhesion layers (Ti. Cr, Co and Ni) between the glass surface and the aluminium coating produced, especially for tube-etched tips, a significant increase in the optical destruction threshold. With increasingly thin metal coatings, the use of a protection coating that prevents corrosion during aging is recommended. An additional increase in optical stability was achieved by applying mixed-metal coatings: alternating thin titanium and thick aluminium layers yielded fibre probes with superior properties that achieved average optical destruction thresholds of > 270 microJ. This is an increase in stability of > 400% compared with conventionally fabricated near-field optical tips.

  10. HADES - Hydrophone for Acoustic Detection at South Pole

    CERN Document Server

    Semburg, Benjamin

    2008-01-01

    The South Pole Acoustic Test Setup (SPATS) is located in the upper part of the optical neutrino observatory IceCube, currently under construction. SPATS consists of four strings at depths between 80 m and 500 m below the surface of the ice with seven stages per string. Each stage is equipped with an acoustic sensor and a transmitter. Three strings (string A-C) were deployed in the austral summer 2006/07. SPATS was extended by a fourth string (string D) with second generation sensors and transmitters in 2007/08. One second generation sensor type HADES (Hydrophone for Acoustic Detection at South Pole) consists of a ring-shaped piezo-electric element coated with polyurethane. The development of the sensor, optimization of acoustic transmission by acoustic impedance matching and first in-situ results will be discussed.

  11. Optical sensors and their applications for probing biological systems

    DEFF Research Database (Denmark)

    Palanco, Marta Espina

    and mammalian cells. First, we performed Surface Enhanced Raman Spectroscopy (SERS) studies on intact plant materials via using silver plasmonic nanostructures. Our studies showed strong Raman signals which resemble to the presence of typical constituents such as carbohydrates, proteins and lipids of different......There is a great interest in exploring and developing new optical sensitive methodologies for probing complex biological systems. In this project we developed non-invasive and sensitive biosensor strategies for studying physiologically relevant chemical and physical properties of plant...... biological sample to provide a SERS-template where silver nanoparticles can grow, thus providing a new insight into SERS-based sensors for chemically sensing in-situ plant constituents. Optical manipulation techniques have been used to investigate mechanical properties of soft membrane cells, i.e. mammalian...

  12. Interferometric strain measurements with a fiber-optic probe

    Science.gov (United States)

    Burnham-Fay, E. D.; Jacobs-Perkins, D. W.; Ellis, J. D.

    2015-09-01

    Experience at the Laboratory for Laser Energetics has shown that broadband base vibrations make it difficult to position cryogenic inertial confinement fusion targets. These effects must be mitigated for National Ignition Facility-scale targets; to this end an active vibration stabilization system is proposed. A single-mode optical fiber strain probe and a novel fiber contained heterodyne interferometer have been developed as a position feedback sensor for the vibration control system. A resolution limit of 54.5 nƐ; is measured with the optical strain gauge, limited by the lock-in amplifier. Experimental measurements of the sensor that show good agreement with reference resistive strain gauge measurements are presented.

  13. Research of DOA Estimation Based on Single MEMS Vector Hydrophone

    Directory of Open Access Journals (Sweden)

    Wen Dong Zhang

    2009-08-01

    Full Text Available The MEMS vector hydrophone is a novel acoustic sensor with a “four-beamcilia” structure. Based on the MEMS vector hydrophone with this structure, the paper studies the method of estimated direction of arrival (DOA. According to various research papers, many algorithms can be applied to vector hydrophones. The beam-forming approach and bar graph approach are described in detail. Laboratory tests by means of the a standing-wave tube are performed to validate the theoretical results. Both the theoretical analysis and the results of tests prove that the proposed MEMS vector hydrophone possesses the desired directional function.

  14. Research of DOA Estimation Based on Single MEMS Vector Hydrophone.

    Science.gov (United States)

    Zhang, Wen Dong; Guan, Ling Gang; Zhang, Guo Jun; Xue, Chen Yang; Zhang, Kai Rui; Wang, Jian Ping

    2009-01-01

    The MEMS vector hydrophone is a novel acoustic sensor with a "four-beam-cilia" structure. Based on the MEMS vector hydrophone with this structure, the paper studies the method of estimated direction of arrival (DOA). According to various research papers, many algorithms can be applied to vector hydrophones. The beam-forming approach and bar graph approach are described in detail. Laboratory tests by means of the a standing-wave tube are performed to validate the theoretical results. Both the theoretical analysis and the results of tests prove that the proposed MEMS vector hydrophone possesses the desired directional function.

  15. Electromagnetic Hydrophone with Tomographic System for Absolute Velocity Field Mapping

    CERN Document Server

    Grasland-Mongrain, Pol; Mari, Jean-Martial; Chapelon, Jean-Yves; Lafon, Cyril; 10.1063/1.4726178

    2012-01-01

    The velocity and pressure of an ultrasonic wave can be measured by an electromagnetic hydrophone made of a thin wire and a magnet. The ultrasonic wave vibrates the wire inside a magnetic field, inducing an electrical current. Previous articles reported poor spatial resolution of comparable hydrophones along the axis of the wire. In this study, submillimetric spatial resolution has been achieved by using a tomographic method. Moreover, a physical model is presented for obtaining absolute measurements. A pressure differential of 8% has been found between piezoelectric and electromagnetic hydrophone measurements. These characteristics show this technique as an alternative to standard hydrophones.

  16. Bow-tie optical antenna probes for single-emitter scanning near-field optical microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Farahani, Javad N [Nano-Optics Group, National Center of Competence for Research in Nanoscale Science, Institute of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Eisler, Hans-Juergen [Nano-Optics Group, National Center of Competence for Research in Nanoscale Science, Institute of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Pohl, Dieter W [Nano-Optics Group, National Center of Competence for Research in Nanoscale Science, Institute of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Pavius, Michael [Center of MicroNanoTechnology (CMI), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Flueckiger, Philippe [Center of MicroNanoTechnology (CMI), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Gasser, Philippe [EMPA, Swiss Federal Laboratories for Materials Testing and Research, Electronics/Metrology Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Hecht, Bert [Nano-Optics Group, National Center of Competence for Research in Nanoscale Science, Institute of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland)

    2007-03-28

    A method for the fabrication of bow-tie optical antennas at the apex of pyramidal Si{sub 3}N{sub 4} atomic force microscopy tips is described. We demonstrate that these novel optical probes are capable of sub-wavelength imaging of single quantum dots at room temperature. The enhanced and confined optical near-field at the antenna feed gap leads to locally enhanced photoluminescence (PL) of single quantum dots. Photoluminescence quenching due to the proximity of metal is found to be insignificant. The method holds promise for single quantum emitter imaging and spectroscopy at spatial resolution limited by the engineered antenna gap width exclusively.

  17. Ultrafast Radiation Detection by Modulation of an Optical Probe Beam

    Energy Technology Data Exchange (ETDEWEB)

    Vernon, S P; Lowry, M E

    2006-02-22

    We describe a new class of radiation sensor that utilizes optical interferometry to measure radiation-induced changes in the optical refractive index of a semiconductor sensor medium. Radiation absorption in the sensor material produces a transient, non-equilibrium, electron-hole pair distribution that locally modifies the complex, optical refractive index of the sensor medium. Changes in the real (imaginary) part of the local refractive index produce a differential phase shift (absorption) of an optical probe used to interrogate the sensor material. In contrast to conventional radiation detectors where signal levels are proportional to the incident energy, signal levels in these optical sensors are proportional to the incident radiation energy flux. This allows for reduction of the sensor form factor with no degradation in detection sensitivity. Furthermore, since the radiation induced, non-equilibrium electron-hole pair distribution is effectively measured ''in place'' there is no requirement to spatially separate and collect the generated charges; consequently, the sensor risetime is of the order of the hot-electron thermalization time {le} 10 fs and the duration of the index perturbation is determined by the carrier recombination time which is of order {approx} 600 fs in, direct-bandgap semiconductors, with a high density of recombination defects; consequently, the optical sensors can be engineered with sub-ps temporal response. A series of detectors were designed, and incorporated into Mach Zehnder and Fabry-Perot interferometer-based detection systems: proof of concept, lower detection sensitivity, Mach-Zehnder detectors were characterized at beamline 6.3 at SSRL; three generations of high sensitivity single element and imaging Fabry-Perot detectors were measured at the LLNL Europa facility. Our results indicate that this technology can be used to provide x-ray detectors and x-ray imaging systems with single x-ray sensitivity and S

  18. A portable optical fiber probe for in vivo brain temperature measurements

    Science.gov (United States)

    Musolino, Stefan; Schartner, Erik P.; Tsiminis, Georgios; Salem, Abdallah; Monro, Tanya M.; Hutchinson, Mark R.

    2016-11-01

    We report on the development of an optical fiber based probe for in vivo measurements of brain temperature. By using a thin layer of rare-earth doped tellurite glass on the tip of a silica optical fiber a durable probe, suitable for long-term in vivo measurements of temperature can be fabricated. The probe can be interrogated using a portable optical measurement setup, allowing for measurements to be performed outside of standard optical laboratories as no alignment of components is required. This setup is deployed to a medical research laboratory to show preliminary results on the use of these optical fibers for in vivo pre-clinical measurements of brain temperature.

  19. Fiber-optic laser Doppler turbine tip clearance probe.

    Science.gov (United States)

    Büttner, Lars; Pfister, Thorsten; Czarske, Jürgen

    2006-05-01

    A laser Doppler based method for in situ single blade tip clearance measurements of turbomachines with high precision is presented for what we believe is the first time. The sensor is based on two superposed fanlike interference fringe systems generated by two laser wavelengths from a fiber-coupled, passive, and therefore compact measurement head employing diffractive optics. Tip clearance measurements at a transonic centrifugal compressor performed during operation at 50,000 rpm (833 Hz, 586 m/s tip speed) are reported. At these speeds the measured uncertainty of the tip position was less than 20 microm, a factor of 2 more accurate than that of capacitive probes. The sensor offers great potential for in situ and online high-precision tip clearance measurements of metallic and nonmetallic turbine blades.

  20. Infrared fiber optic probes for evaluation of musculoskeletal tissue pathology

    Science.gov (United States)

    Padalkar, Mugdha; McGoverin, Cushla; Onigbanjo, Quam; Spencer, Richard; Barbash, Scott; Kropf, Eric; Pleshko, Nancy

    2014-03-01

    Musculoskeletal pathology of the knee commonly occurs with aging and as a result of injury. The incidence of anterior cruciate ligament (ACL) injuries continues to increase annually, and may precede the eventual onset of osteoarthritis (OA), a debilitating and prevalent disease characterized by cartilage degeneration. Early detection of OA remains elusive, with current imaging methods lacking adequate sensitivity to detect early pathologic cartilage changes. We used mid- and near- infrared (IR) spectroscopy through arthroscopic-based fiber-optic devices to assess cartilage damage and differentiate tendon from ligament. Mid-IR spectroscopy is characterized by distinct bands and low penetration depth (ligaments and tendons. We discuss here basic science studies and the potential for translation to clinical research with novel arthroscopic probes.

  1. Direct Optical Probing of Transverse Electric Mode in Graphene

    CERN Document Server

    Menabde, Sergey; Kornev, Evgeny; Lee, Changhee; Park, Namkyoo

    2015-01-01

    Unique electrodynamic response of graphene implies a manifestation of an unusual propagating and localised transverse-electric (TE) mode near the spectral onset of interband transitions. However, excitation and further detection of the TE mode supported by graphene is considered to be a challenge for it is extremely sensitive to excitation environment and phase matching condition adherence. Here for the first time, we experimentally prove an existence of the TE mode by its direct optical probing, demonstrating significant coupling to an incident wave in electrically doped multilayer graphene sheet at room temperature. We believe that proposed technique of careful phase matching and obtained access to graphene TE excitation would stimulate further studies of this unique phenomenon, and enable its potential employing in various fields of photonics as well as for characterization of graphene.

  2. Optical transponder DC probe [for pulsed power generator

    CERN Document Server

    Thompson, M C

    1999-01-01

    The Atlas Pulse Power, Marx Bank will produce significant electromagnetic interference potential (EMI) via its 192 spark-gaps and trigger systems (36 more spark gaps). The authors have a need to measure DC charge components to a fair degree of accuracy during charge to ensure a safe and balanced system. Isolation from elevated- deck and/or high EMI environments during DC voltage or current measurement has classically been approached using frequency modulation (FM) of an imposed carrier on an optical fiber coupled system. There are shortcomings in most systems that can generally be compensated for by various means. In their application of remote sensing, the power to run this remote probe was a central issue. As such the authors took another approach to monitor the DC charge record for the Atlas' Marx banks. (0 refs).

  3. Molecular probes for nonlinear optical imaging of biological membranes

    Science.gov (United States)

    Blanchard-Desce, Mireille H.; Ventelon, Lionel; Charier, Sandrine; Moreaux, Laurent; Mertz, Jerome

    2001-12-01

    Second-harmonic generation (SHG) and two-photon excited fluorescence (TPEF) are nonlinear optical (NLO) phenomena that scale with excitation intensity squared, and hence give rise to an intrinsic 3-dimensional resolution when used in microscopic imaging. TPEF microscopy has gained widespread popularity in the biology community whereas SHG microscopy promises to be a powerful tool because of its sensitivity to local asymmetry. We have implemented an approach toward the design of NLO-probes specifically adapted for SHG and/or TPEF imaging of biological membranes. Our strategy is based on the design of nanoscale amphiphilic NLO-phores. We have prepared symmetrical bolaamphiphilic fluorophores combining very high two-photon absorption (TPA) cross-sections in the visible red region and affinity for cellular membranes. Their incorporation and orientation in lipid membranes can be monitored via TPEF anisotropy. We have also prepared amphiphilic push-pull chromophores exhibiting both large TPA cross-sections and very large first hyperpolarizabilities in the near-IR region. These NLO-probes have proved to be particularly useful for imaging of biological membranes by simultaneous SHG and TPEF microscopy and offer attractive prospects for real-time imaging of fundamental biological processes such as adhesion, fusion or reporting of membrane potentials.

  4. Improved "optical highlighter" probes derived from discosoma red fluorescent protein.

    Science.gov (United States)

    Robinson, Lisbeth C; Marchant, Jonathan S

    2005-02-01

    The tetrameric red fluorescent protein, DsRed, undergoes a rapid red to green color change evoked by short wavelength (lambda highlighter" probe for tracking live cells, organelles, and fusion proteins. This color change results from selective bleaching of the "mature" red-emitting species of DsRed and an enhancement of emission from the "immature" green species, likely caused by dequenching of fluorescence resonance energy transfer occurring within the protein tetramer. Here, we have examined the role of residues known to influence the rate and completeness of chromophore maturation on the cellular and biophysical properties of DsRed mutants. Surprisingly, a single amino acid mutation (N42Q) with increased basal green emission yet rapid chromophore maturation displayed a multiphoton-evoked color change that was brighter, more consistent, more vivid, and easier to evoke than DsRed, despite the larger proportion of green chromophores. Rapidly maturing mutants with more complete chromophore maturation, exhibited little color change and increased resistance to multiphoton bleaching. We describe improved optical and cell biological properties for two DsRed-derived variants which we showcase in photolabeling studies, and discuss these data in terms of implications for fluorescence resonance energy transfer-based probes.

  5. Proceedings of "Optical Probes of Dynamics in Complex Environments"

    Energy Technology Data Exchange (ETDEWEB)

    Sension, R; Tokmakoff, A

    2008-04-01

    This document contains the proceedings from the symposium on Optical Probes of Dynamics in Complex Environments, which organized as part of the 235th National Meeting of the American Chemical Society in New Orleans, LA from April 6 to 10, 2008. The study of molecular dynamics in chemical reaction and biological processes using time ƒresolved spectroscopy plays an important role in our understanding of energy conversion, storage, and utilization problems. Fundamental studies of chemical reactivity, molecular rearrangements, and charge transport are broadly supported by the DOE Office of Science because of their role in the development of alternative energy sources, the understanding of biological energy conversion processes, the efficient utilization of existing energy resources, and the mitigation of reactive intermediates in radiation chemistry. In addition, time resolved spectroscopy is central to all of DOEs grand challenges for fundamental energy science. This symposium brought together leaders in the field of ultrafast spectroscopy, including experimentalists, theoretical chemists, and simulators, to discuss the most recent scientific and technological advances. DOE support for this conference was used to help young US and international scientists travel to the meeting. The latest technology in ultrafast infrared, optical, and xray spectroscopy and the scientific advances that these methods enable were covered. Particular emphasis was placed on new experimental methods used to probe molecular dynamics in liquids, solids, interfaces, nanostructured materials, and biomolecules.

  6. Fiber-optic polarization diversity detection for rotary probe optical coherence tomography.

    Science.gov (United States)

    Lee, Anthony M D; Pahlevaninezhad, Hamid; Yang, Victor X D; Lam, Stephen; MacAulay, Calum; Lane, Pierre

    2014-06-15

    We report a polarization diversity detection scheme for optical coherence tomography with a new, custom, miniaturized fiber coupler with single mode (SM) fiber inputs and polarization maintaining (PM) fiber outputs. The SM fiber inputs obviate matching the optical lengths of the X and Y OCT polarization channels prior to interference and the PM fiber outputs ensure defined X and Y axes after interference. Advantages for this scheme include easier alignment, lower cost, and easier miniaturization compared to designs with free-space bulk optical components. We demonstrate the utility of the detection system to mitigate the effects of rapidly changing polarization states when imaging with rotating fiber optic probes in Intralipid suspension and during in vivo imaging of human airways.

  7. Optical probe design with extended depth-of-focus for optical coherence microscopy and optical coherence tomography

    Science.gov (United States)

    Lee, Seungwan; Choi, Minseog; Lee, Eunsung; Jung, Kyu-Dong; Chang, Jong-hyeon; Kim, Woonbae

    2013-03-01

    In this report, Optical probe system for modality, optical coherence tomography (OCT) and optical coherence microscope (OCM), is presented. In order to control the back focal length from 2.2 mm to 27 mm, optical probe is designed using two liquid lenses and several lenses. The narrow depth of focus (DOF) in microscope is extended by phase filter such as cubic filter. The filter is modified so that DOF is extended only In the OCM mode. The section for the extended DOF of probe is controlled by iris. Therefore in OCT mode, the phase filter does not affect on the DOF of lens. In OCM mode, the Gaussian light and modified light will affect the DOF. The probe dimension is less than 4 mm diameter and less than 60 mm long. The scan range of system is 0.88 mm wide, 1 mm deep in the OCT and 510 μm wide, 1 mm deep in the OCM mode. The lens curvature and iris aperture are operated by digital microelectrofluidic lens and iris.

  8. Single molecule mapping of the optical field distribution of probes for near-field microscopy

    NARCIS (Netherlands)

    Veerman, J.A.; Garcia Parajo, M.F.; Kuipers, L.; van Hulst, N.F.

    1999-01-01

    The most difficult task in near-field scanning optical microscopy (NSOM) is to make a high quality subwavelength aperture probe, Recently we have developed high definition NSOM probes by focused ion beam (FIB) milling. These probes have a higher brightness, better polarization characteristics,

  9. Single molecule mapping of the optical field distribution of probes for near-field microscopy

    NARCIS (Netherlands)

    Veerman, J.A.; Garcia-Parajo, M.F.; Kuipers, L.; Hulst, van N.F.

    1999-01-01

    The most difficult task in near-field scanning optical microscopy (NSOM) is to make a high quality subwavelength aperture probe, Recently we have developed high definition NSOM probes by focused ion beam (FIB) milling. These probes have a higher brightness, better polarization characteristics, bette

  10. Electric field and temperature measurement using ultra wide bandwidth pigtailed electro-optic probes.

    Science.gov (United States)

    Bernier, Maxime; Gaborit, Gwenaël; Duvillaret, Lionel; Paupert, Alain; Lasserre, Jean-Louis

    2008-05-01

    We present pigtailed electro-optic probes that allow a simultaneous measurement of high frequency electric fields and temperature using a unique laser probe beam. This has been achieved by the development of a novel probe design associated with a fully automated servo-controlled optical bench, initially developed to stabilize the electric field sensor response. The developed electro-optic probes present a stable response in outdoors conditions over a time duration exceeding 1 h, a frequency bandwidth from kHz to tens of GHz with a sensitivity of 0.7 Vm(-1)Hz(-(1/2)), and a temperature accuracy of 40 mK.

  11. Development of Fiber-Optic Humidity Sensor Probe with Gelatin Cladding

    Directory of Open Access Journals (Sweden)

    Akhiruddin Maddu

    2010-10-01

    Full Text Available Humidity sensor based on optical fiber with gelatin cladding has been developed. In this humidity sensor probe, the origin cladding of optical fiber is replaced by gelatin coating as humidity sensitive cladding. Testing of the optical fiber sensor probe was conducted by measuring of light intensity transmitted on the optical fiber probe for each variation of different humidity treatments. Response of the optical fiber sensor probe measured from 42%RH to 99%RH, the results show an optical transmission curve varied with relative humidity (RH. Optical transmission in the optical fiber probe increase with RH value at a specific wavelength range, that is from green to red spectrum bands (500 nm - 700 nm, where a significant variation from 600 nm to 650 nm in yellow to red spectrum bands. Wavelength where is a maximum intensity of optical transmission occurs at 610 nm. Therefore, the optical fiber humidity sensor probe could response humidity form 42%RH to 99%RH with the best response in humidity range of 60%RH to 72%RH that is have a good  linearity and sensitivity

  12. Investigation on Dynamic Calibration for an Optical-Fiber Solids Concentration Probe in Gas-Solid Two-Phase Flows

    OpenAIRE

    Changsui Zhao; Liu Shen; Pan Xu; Xiaoping Chen; Daoyin Liu; Cai Liang; Guiling Xu

    2013-01-01

    This paper presents a review and analysis of the research that has been carried out on dynamic calibration for optical-fiber solids concentration probes. An introduction to the optical-fiber solids concentration probe was given. Different calibration methods of optical-fiber solids concentration probes reported in the literature were reviewed. In addition, a reflection-type optical-fiber solids concentration probe was uniquely calibrated at nearly full range of the solids concentration from 0...

  13. Probing the Active Galactic Nuclei using optical spectroscopy

    Science.gov (United States)

    Vivek, M.

    Variability studies offer one of the best tools for understanding the physical conditions present in regions close to the central engine in an AGN. We probed the various properties of AGN through time variability studies of spectral lines in the optical wavelengths using the 2m telescope in IUCAA Girawali observatory. The absorption line variability studies are mainly concentrated in understanding the nature of outflows in quasars. Quasar outflows have a huge impact on the evolution of central supermassive blackholes, their host galaxies and the surrounding intergalactic medium. Studying the variability in these Broad Absorption Lines (BALs) can help us understand the structure, evolution, and basic physical properties of these outflows. We conducted a repeated Low ionization BAL monitoring program with 27 LoBALs (Low Ionization BALs) at z 0.3-2.1 covering timescales from 3.22 to 7.69 years in the quasar rest frame. We see a variety of phenomena, including some BALs that either appeared or disappeared completely and some BALs which do not vary over the observation period. In one case, the excited fine structure lines have changed dramatically. One source shows signatures of radiative acceleration. Here, we present the results from this program. Emission line studies are concentrated in understanding the peculiar characteristics of a dual-AGN source SDSS J092712.64+294344.0.

  14. Optical Nanofiber Integrated into Optical Tweezers for In Situ Fiber Probing and Optical Binding Studies

    Directory of Open Access Journals (Sweden)

    Ivan Gusachenko

    2015-07-01

    Full Text Available Precise control of particle positioning is desirable in many optical propulsion and sorting applications. Here, we develop an integrated platform for particle manipulation consisting of a combined optical nanofiber and optical tweezers system. We show that consistent and reversible transmission modulations arise when individual silica microspheres are introduced to the nanofiber surface using the optical tweezers. The observed transmission changes depend on both particle and fiber diameter and can be used as a reference point for in situ nanofiber or particle size measurement. Thence, we combine scanning electron microscope (SEM size measurements with nanofiber transmission data to provide calibration for particle-based fiber assessment. This integrated optical platform provides a method for selective evanescent field manipulation of micron-sized particles and facilitates studies of optical binding and light-particle interaction dynamics.

  15. Fiber-optic confocal microscopy using a miniaturized needle-compatible imaging probe

    Science.gov (United States)

    Pillai, Rajesh S.; Lorenser, Dirk; Sampson, David D.

    2011-05-01

    We report on the design and implementation of a 350 μm-diameter confocal imaging probe based on gradient-index (GRIN) optics and a fiber-based scanning arrangement. The form factor of the probe is such that it can potentially be inserted into a 22-gauge hypodermic needle to perform high-resolution confocal fluorescence imaging in solid tissues. We introduce a simple scanning arrangement based on lensed fiber, which eliminates off-axis aberrations induced by conventional scanning optics and is suitable for integration into a compact hand-held unit. We present the details of the optical design and experimental verification of the performance of the optical system. The measured lateral resolution of ~700 nm is in agreement with the optical design and is the highest resolution reported for a confocal fluorescence imaging probe of this size. Further, we demonstrate the imaging capability of the probe by obtaining high-resolution images of fluorescently labeled muscle fibers.

  16. Optical probe for the cytochrom P-450 cholesterol side chain cleavage enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Marrone, B.L.; Simpson, D.J.; Unkefer, C.J.; Whaley, T.W.

    1992-05-05

    This patent describes a method for quantifying the activity of the P-450[sub scc] enzyme in the conversion of cholesterol to pregnenolone in steroidogenesis, forming a fluorogenic probe having a cholesterol-based steroid connected through a linking group at the C-22 position with a chromophore effective to have a low optical response when attached to the steroid and a high optical response as an anion, incorporating the probe in a process for the conversion of cholesterol to pregnenolone; reacting the probe with the P-450[sub scc] enzyme to cleave the side-chain from the probe and form the anion having the high optical response from the chromophore; and exciting the anion to obtain the high optical response; and optically detecting the response as a measure of the P-450[sub scc] enzyme activity.

  17. Fibre Optics in Undersea Applications

    Directory of Open Access Journals (Sweden)

    A. K. Talwar

    1984-01-01

    Full Text Available Role of optical fibres for underwater communication cables and hydrophones is discussed. The fibre optics cables provide an excellent solution to the historical bandwidth-diameter problems of conventional coaxial cables.Fibre optic hydrophones are found to have many more advantages apart from high sensitivity and large dynamic range, over the classical sound sensors used in underwater work.

  18. Dynamics of trapped atoms around an optical nanofiber probed through polarimetry

    Science.gov (United States)

    Solano, Pablo; Fatemi, Fredrik K.; Orozco, Luis A.; Rolston, S. L.

    2017-06-01

    The evanescent field outside an optical nanofiber (ONF) can create optical traps for neutral atoms. We present a non-destructive method to characterize such trapping potentials. An off-resonance linearly polarized probe beam that propagates through the ONF experiences a slow axis of polarization produced by trapped atoms on opposite sides along the ONF. The transverse atomic motion is imprinted onto the probe polarization through the changing atomic index of of refraction. By applying a transient impulse, we measure a time-dependent polarization rotation of the probe beam that provides both a rapid and non-destructive measurement of the optical trapping frequencies.

  19. Focussed ion beam machined cantilever aperture probes for near-field optical imaging.

    Science.gov (United States)

    Jin, E X; Xu, X

    2008-03-01

    Near-field optical probe is the key element of a near-field scanning optical microscopy (NSOM) system. The key innovation in the first two NSOM experiments (Pohl et al., 1984; Lewis et al., 1984) is the fabrications of a sub-wavelength optical aperture at the apex of a sharply pointed transparent probe tip with a thin metal coating. This paper discusses the routine use of focussed ion beam (FIB) to micro-machine NSOM aperture probes from the commercial silicon nitride cantilevered atomic force microscopy probes. Two FIB micro-machining approaches are used to form a nanoaperture of controllable size and shape at the apex of the tip. The FIB side slicing produces a silicon nitride aperture on the flat-end tips with controllable sizes varying from 120 nm to 30 nm. The FIB head-on drilling creates holes on the aluminium-coated tips with sizes down to 50 nm. Nanoapertures in C and bow tie shapes can also be patterned using the FIB head-on milling method to possibly enhance the optical transmission. A transmission-collection NSOM system is constructed from a commercial atomic force microscopy to characterize the optical resolution of FIB-micro-machined aperture tips. The optical resolution of 78 nm is demonstrated by an aperture probe fabricated by FIB head-on drilling. Simultaneous topography imaging can also be realized using the same probe. By mapping the optical near-field from a bow-tie aperture, optical resolution as small as 59 nm is achieved by an aperture probe fabricated by the FIB side slicing method. Overall, high resolution and reliable optical imaging of routinely FIB-micro-machined aperture probes are demonstrated.

  20. Information Storage and Retrieval for Probe Storage using Optical Diffraction Patterns

    CERN Document Server

    van Honschoten, Joost; Koelmans, Wabe W; Parnell, Thomas P; Zaboronski, Oleg V

    2011-01-01

    A novel method for fast information retrieval from a probe storage device is considered. It is shown that information can be stored and retrieved using the optical diffraction patterns obtained by the illumination of a large array of cantilevers by a monochromatic light source. In thermo-mechanical probe storage, the information is stored as a sequence of indentations on the polymer medium. To retrieve the information, the array of probes is actuated by applying a bending force to the cantilevers. Probes positioned over indentations experience deflection by the depth of the indentation, probes over the flat media remain un-deflected. Thus the array of actuated probes can be viewed as an irregular optical grating, which creates a data-dependent diffraction pattern when illuminated by laser light. We develop a low complexity modulation scheme, which allows the extraction of information stored in the pattern of indentations on the media from Fourier coefficients of the intensity of the diffraction pattern. We th...

  1. Broadband sensitive pump-probe setup for ultrafast optical switching of photonic nanostructures and semiconductors

    NARCIS (Netherlands)

    Euser, T.G.; Harding, P.J.; Vos, Willem L.

    2009-01-01

    We describe an ultrafast time resolved pump-probe spectroscopy setup aimed at studying the switching of nanophotonic structures. Both femtosecond pump and probe pulses can be independently tuned over broad frequency range between 3850 and 21 050 cm−1. A broad pump scan range allows a large optical

  2. Bubble shape and orientation determination with a four-point optical fibre probe

    NARCIS (Netherlands)

    Guet, S.; Luther, S.; Ooms, G.

    2003-01-01

    We propose a new method to estimate the aspect ratio and orientation of bubbles by using their time series obtained with a four-point optical-fibre probe. The feasibility and accuracy of the method was first analysed by using synthetic bubble–probe interaction data and single bubble experiments in p

  3. ¿/4 Resonance of an Optical Monopole Antenna Probed by Single Molecule Fluorescence

    NARCIS (Netherlands)

    Taminiau, Tim H.; Moerland, R.J.; Segerink, Franciscus B.; Kuipers, L.; van Hulst, N.F.

    2007-01-01

    We present a resonant optical nanoantenna positioned at the end of a metal-coated glass fiber near-field probe. Antenna resonances, excitation conditions, and field localization are directly probed in the near field by single fluorescent molecules and compared to finite integration technique

  4. Single Camera 3-D Coordinate Measuring System Based on Optical Probe Imaging

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new vision coordinate measuring system——single camera 3-D coordinate measuring system based on optical probe imaging is presented. A new idea in vision coordinate measurement is proposed. A linear model is deduced which can distinguish six freedom degrees of optical probe to realize coordinate measurement of the object surface. The effects of some factors on the resolution of the system are analyzed. The simulating experiments have shown that the system model is available.

  5. Introduction: feature issue on optical molecular probes, imaging, and drug delivery.

    Science.gov (United States)

    Campagnola, Paul; French, Paul M W; Georgakoudi, Irene; Mycek, Mary-Ann

    2014-02-01

    The editors introduce the Biomedical Optics Express feature issue "Optical Molecular Probes, Imaging, and Drug Delivery," which is associated with a Topical Meeting of the same name held at the 2013 Optical Society of America (OSA) Optics in the Life Sciences Congress in Waikoloa Beach, Hawaii, April 14-18, 2013. The international meeting focused on the convergence of optical physics, photonics technology, nanoscience, and photochemistry with drug discovery and clinical medicine. Papers in this feature issue are representative of meeting topics, including advances in microscopy, nanotechnology, and optics in cancer research.

  6. Revealing hidden optical transitions with tuneable optical-pump THz-probe spectroscopy

    CERN Document Server

    Novelli, Fabio

    2016-01-01

    While a vast amount of theoretical and experimental approaches can be used to study the band structure of simple solids, the investigation of the electronic properties of high-temperature superconductors and other strongly correlated systems is far less simple. Limitations to both theory and experiments arise from e.g. the many-body nature of the mathematical problem and from the non-trivial surface reconstructions, respectively. Here we propose a novel approach able to reveal energy gaps between band extrema that cannot be identified from the equilibrium optical properties. By combining finely-tunable visible pump pulses with terahertz probe fields, we identify changes to the transient conductivity as the pump wavelength is changed and the density of carriers in different parts of the band structure varies. This approach is demonstrated on a typical semiconductor, undoped silicon, where we identify the band minimum at the $L$ point of the conduction band, corresponding to the second lowest energy indirect ga...

  7. Phase generated carrier technique for fiber laser hydrophone

    Science.gov (United States)

    Li, Rizhong; Wang, Xinbing; Huang, Junbin; Gu, Hongcan

    2013-08-01

    A distributed feedback (DFB) fiber laser is compact, and is very suitable for using as a hydrophone to sense acoustic pressure. A DFB fiber laser hydrophone was researched. In the fiber laser hydrophone signal demodulating system, an unbalanced Michelson fiber interferometer and a Phase Generated Carrier (PGC) method were used. The PGC method can be used to demodulating the acoustic signal from the interference signal. Comparing with the Naval Research Laboratory (NRL) method and Naval Postgraduate School (NPS) method, the digitized PGC method requires a greater amount of computation because of the high signal sampling, but it demands only one interference signal which makes the less fiber connections of the fiber laser hydrophone array. So the fiber laser hydrophone array based on the PGC method has lower complexity and higher reliability than that based on the NRL method or NPS method. The experimental results approve that the PGC method can demodulate acoustic signal between 20~2000 Hz frequency range with good signal-to-noise ratio (SNR) when the PZT driving frequency is 20 kHz.

  8. A low background Raman probe for optical biopsy of brain tissue

    Science.gov (United States)

    Stevens, Oliver A. C.; Hutchings, Joanne; Gray, William; Day, John C.

    2014-03-01

    Removal of intrinsic brain tumours is a delicate process, where a high degree of specificity is required to remove all of the tumour tissue without damaging healthy brain. The accuracy of this process can be greatly enhanced by intraoperative guidance. Optical biopsies using Raman spectroscopy are a minimally invasive and lower cost alternative to current guidance methods. A miniature Raman probe for performing optical biopsies of human brain tissue is presented. The probe allows sampling inside a conventional stereotactic brain biopsy system: a needle of length 200mm and inner diameter of 1.8mm. The probe achieves a very low fluorescent background whilst maintaining good collection of Raman signal by employing a miniature stand-off Raman design. To illustrate this, the probe is compared with a Raman probe that uses a pair of optical fibres for collection. The miniature stand-off Raman probe is shown to collect a comparable number of Raman scattered photons, but the fluorescence caused by silica fibres in a Raman needle probe is reduced by a factor of two for Raman shifts under 500 cm-1, and by 30% at 600-700 cm-1. In addition, this design contains only medically approved materials at the distal end. The probe's suitability for use on tissue is demonstrated by discriminating between different types of porcine brain tissue.

  9. Field enhancement analysis of an apertureless near field scanning optical microscope probe with finite element method

    Institute of Scientific and Technical Information of China (English)

    Weibin Chen; Qiwen Zhan

    2007-01-01

    Plasmonic field enhancement in a fully coated dielectric near field scanning optical microscope (NSOM)probe under radial polarization illumination is analyzed using an axially symmetric three-dimensional (3D)finite element method (FEM) model. The enhancement factor strongly depends on the illumination spot size, taper angle of the probe, and the metal film thickness. The tolerance of the alignment angle is investigated. Probe designs with different metal coatings and their enhancement performance are studied as well. The nanometric spot size at the tip apex and high field enhancement of the apertureless NSOM probe have important potential application in semiconductor metrology.

  10. Raman imaging of carious lesions using a hollow optical fiber probe.

    Science.gov (United States)

    Yokoyama, Eriko; Kakino, Satoko; Matsuura, Yuji

    2008-08-10

    Raman spectroscopy using a hollow optical fiber probe with a glass ball lens at the distal end is proposed for detection of early caries lesions. Raman spectroscopy on carious lesions of extracted teeth showed that the probe enables measurement with a high signal-to-noise ratio when combined with a ball lens with a high refractive index. The proposed probe and lens combination detects changes in Raman spectra caused by morphological differences between sound and carious enamel. We also obtained a high-contrast image of an early carious lesion by scanning the tooth surface with the probe.

  11. A heat-sinking self-referencing fiber optic emission probe

    Science.gov (United States)

    Djeu, Nicholas; Shimoji, Yutaka

    2016-09-01

    A novel heat-sinking, self-referencing fiber optic emission probe having a sapphire fiber probe head is described. The laser heating effect in a GaAs wafer (on a polytetrafluoroethylene (PTFE) platform) has been measured with the probe in both the noncontact proximity mode and the contact mode. The GaAs/PTFE composite was selected to simulate the thermal conductivity of animal tissues. It was found that for the same laser power delivered to the wafer, the temperature rise in the contact mode was only 42% of that in the proximity mode. Additionally, a demonstration of the self-referencing capability of the probe is also presented.

  12. Hollow-core photonic crystal fiber-optic probes for Raman spectroscopy.

    Science.gov (United States)

    Konorov, Stanislav O; Addison, Christopher J; Schulze, H Georg; Turner, Robin F B; Blades, Michael W

    2006-06-15

    We have implemented a new Raman fiber-optic probe design based on a hollow-core photonic-crystal excitation fiber surrounded by silica-core collection fibers. The photonic-crystal fiber offers low attenuation at the pump radiation wavelength, mechanical flexibility, high radiation stability, and low background noise. Because the excitation beam is transmitted through air inside the hollow-core fiber, silica Raman scattering is much reduced, improving the quality of the spectra obtained using probes of this design. Preliminary results show that the new probe design decreases the Raman background from the silica by approximately an order of magnitude compared to solid-core silica Raman probes.

  13. Use of optical probes to characterize bubble behavior in gas-solid fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Mainland, M.E.; Welty, J.R. (Oregon State Univ., Corvallis, OR (United States). Dept. of Mechanical Engineering)

    1995-02-01

    Optical probes are used to study gas-solid fluidized-bed hydrodynamics. The probes each consisting of a light source and photodetector separated by a gap are suitable for use at combustion-level temperatures. The methodology to process the signal for calculation of bubble properties such as bubble frequency, local bubble residence time, bubble velocity, pierced length, bubble size, and visible bubble flow is presented. The signal processing technique is independent of bed operating conditions. The probe signal processing methodology is validated by comparing calculated bubble properties based on the probe signal with properties observed on videotapes of a 2-D bed.

  14. Optical probe for the cytochrome P-450 cholesterol side chain cleavage enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Marrone, Babetta L. (Los Alamos, NM); Simpson, Daniel J. (Los Alamos, NM); Unkefer, Clifford J. (Los Alamos, NM); Whaley, Thomas W. (Santa Fe, NM)

    1993-01-01

    An optical probe enables the study of enzyme activity by absorbance spectroscopy or by sensitive fluorescence methods. In particular, the probe provides the ability to monitor the activity of cytochrome P-450.sub.scc enzyme, the rate limiting enzyme for steroid biosynthesis. Located on the inner mitochondrial membrane, P-450.sub.scc catalyzes the conversion of cholesterol to pregnenolone and isocapraldehyde by sequential oxidations of the cholesterol side chain. The fluorogenic probe includes a cholesterol-like steroid linked to a chromophore through a linking group. The chromophore is selected to have little optical response when linked to the steroid substrate and an enhanced optical response when cleaved from the substrate and linking group. Thus, a fluorescent anion that can be optically detected is generated by the side-chain cleavage reaction during steroidogenesis.

  15. Optical probe for the cytochrome P-450 cholesterol side chain cleavage enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Marrone, B.L.; Simpson, D.J.; Unkefer, C.J.; Whaley, T.W.

    1993-05-04

    An optical probe enables the study of enzyme activity by absorbance spectroscopy or by sensitive fluorescence methods. In particular, the probe provides the ability to monitor the activity of cytochrome P-450[sub scc] enzyme, the rate limiting enzyme for steroid biosynthesis. Located on the inner mitochondrial membrane, P-450[sub scc] catalyzes the conversion of cholesterol to prednesolone and isocapraldehyde by sequential oxidations of the cholesterol side chain. The fluorogenic probe includes a cholesterol-like steroid linked to a chromophore through a linking group. The chromophore is selected to have little optical response when linked to the steroid substrate and an enhanced optical response when cleaved from the substrate and linking group. Thus, a fluorescent anion that can be optically detected is generated by the side-chain cleavage reaction during steroidogenesis.

  16. Optical probe for the cytochrome P-450 cholesterol side chain cleavage enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Marrone, Babetta L. (Los Alamos, NM); Simpson, Daniel J. (Los Alamos, NM); Unkefer, Clifford J. (Los Alamos, NM); Whaley, Thomas W. (Santa Fe, NM)

    1992-01-01

    An optical probe enables the study of enzyme activity by absorbance spectroscopy or by sensitive fluorescence methods. In particular, the probe provides the ability to monitor the activity of cytochrome P-450.sub.scc enzyme, the rate limiting enzyme for steroid biosynthesis. Located on the inner mitochondrial membrane, P-450.sub.scc catalyzes the conversion of cholesterol to pregnenolone and isocapraldehyde by sequential oxidations of the cholesterol side chain. The fluorogenic probe includes a cholesterol-like steroid linked to a chromophore through a linking group. The chromophore is selected to have little optical response when linked to the steroid substrate and an enhanced optical response when cleaved from the substrate and linking group. Thus, a fluorescent anion that can be optically detected is generated by the side-chain cleavage reaction during steroidogenesis.

  17. Near-field optical microscopy of localized excitations on rough surfaces: influence of a probe

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.

    1999-01-01

    Starting from the general principles of near-field optical microscopy. I consider the influence of a probe when being used to image localized dipolar excitations and suggest a way of evaluating the perturbation thus introduced. Using the rigorous microscopic (electric) point-dipole description, I...... calculate the self consistent field intensity at the site of a probe dipole scanning over resonantly interacting object dipoles and show that the intensity distribution deviates from that existing in the absence of a probe. I demonstrate that this difference increases with an increase in the polarizability...... of the probe dipole, resulting eventually in a completely different intensity distribution, The calculations also show that the perturbation of the intensity distribution due to the presence of a probe decreases with an increase in the probe-sample distance. In order to evaluate the degree of perturbation, I...

  18. Miniaturized magnetic-driven scanning probe for endoscopic optical coherence tomography.

    Science.gov (United States)

    Pang, Ziwei; Wu, Jigang

    2015-06-01

    We designed and implemented a magnetic-driven scanning (MDS) probe for endoscopic optical coherence tomography (OCT). The probe uses an externally-driven tiny magnet in the distal end to achieve unobstructed 360-degree circumferential scanning at the side of the probe. The design simplifies the scanning part inside the probe and thus allows for easy miniaturization and cost reduction. We made a prototype probe with an outer diameter of 1.4 mm and demonstrated its capability by acquiring OCT images of ex vivo trachea and artery samples from a pigeon. We used a spectrometer-based Fourier-domain OCT system and the system sensitivity with our prototype probe was measured to be 91 dB with an illumination power of 850 μW and A-scan exposure time of 1 ms. The axial and lateral resolutions of the system are 6.5 μm and 8.1 μm, respectively.

  19. Fabrication of Pure Silica Core Multimode Ultraviolet Optical Fibre Probes by Tube Etching

    Institute of Scientific and Technical Information of China (English)

    HUO Xin; PAN Shi; WU Shi-Fa

    2007-01-01

    As a light wave-guide component for transmitting ultraviolet (UV) laser pulses, pure silica core UV fibre probes have attracted a great deal of attention in the near-field optical data storage and bio-medical studies. We fabricate UV fibre probes with tips in dimension of about 2-5μm and taper angle 16° by the tube etching method, using 40% HF acid as etching solution and xylene as overlayer. Probes produced have curvy configuration with smooth surface. The yield of fine probes is rather high and etching operation greatly simplified. With higher damage threshold, pure silica core multimode UV fibre probes can be coupled into more laser power. In addition, using UV light reduces the cutoff wavelength of the fibre probes, which is in favour of increasing the transmission efficiency of the probe. Furthermore, the larger tip dimension helps to enhance the light throughput either. The advances of fabrication technique of UV optical fibre probe may further support the studies of UV light data storage, pulsed laser biosurgery and UV photolithography.

  20. Computational analysis of responses of a wedge-shaped-tip optical fiber probe in bubble measurement.

    Science.gov (United States)

    Sakamoto, A; Saito, T

    2012-07-01

    Optical-fiber probing is widely employed in bubble/droplet measurement in gas-liquid two-phase flows. Several types of optical fiber probes with a very high S/N ratio and high performance have been developed, but further improvement in the probes' measurement accuracy and reliability for industrial applications is desired. We tried to eliminate optical noise in the probe measurements, and we found that the signals include some peak signs that have potential for advanced measurement with optical-fiber probing. We developed a ray-tracing numerical simulator and identified the mechanisms underlying the generation of the signals. In order to numerically simulate the optical probing signals, the simulator must use 3D frameworks composed of incident beams, the reflection and refraction on the surfaces of the optical elements (i.e., an optical fiber, a sensing tip, an air phase, and a water phase), and beams returning from the sensing tip to the other tip through the fiber. We used all of these in a simple rendering framework based on a ray-tracing algorithm with Fresnel's law, and we observed the mechanism of some promising signals that may be useful for extracting the hidden potential of optical-fiber probing. To verify the simulator's performance, we carried out three comparative experiments with fundamental setups using a wedge-shaped single-tip optical fiber probe, examining: (1) the beam trajectories and energy leaking out from the sensing tip into the surrounding air phase or water phase, (2) the probing signals throughout penetration of the sensing tip at the air-water free interface in light of the three-dimensional deformation, and (3) the probing signals throughout penetration of the sensing tip into a bubble in light of the three-dimensional bubble shape. As a result, (a) we found that an optical fiber probe with a wedge-shaped tip has particular characteristics of beam emissions from the tip, and the emitting angles switched depending on the phases covering

  1. ACADEMIC TRAINING: Probing nature with high precision; particle traps, laser spectroscopy and optical combs

    CERN Multimedia

    Françoise Benz

    2002-01-01

    17, 18, 19 June LECTURE SERIES from 11.00 to 12.00 hrs - Auditorium, bldg. 500 Probing nature with high precision; particle traps, laser spectroscopy and optical combs by G. GABRIELSE / Harvard University, USA Experiments with atomic energy scales probe nature and its symmetries with exquisite precision. Particle traps allow the manipulation of single charged particles for months at a time, allow the most accurate comparison of theory and experiment, and promise to allow better measurement of fundamental quantities like the fine structure constant. Ions and atoms can be probed with lasers that are phase locked to microwave frequency standards via optical combs, thus calibrating optical sources in terms of the official cesium second. A series of three lectures will illustrate what can be measured and discuss key techniques.  ACADEMIC TRAINING Françoise Benz Tel. 73127 francoise.benz@cern.ch

  2. Resolving phase information of the optical local density of state with scattering near-field probes

    Science.gov (United States)

    Prasad, R.; Vincent, R.

    2016-10-01

    We theoretically discuss the link between the phase measured using a scattering optical scanning near-field microscopy (s-SNOM) and the local density of optical states (LDOS). A remarkable result is that the LDOS information is directly included in the phase of the probe. Therefore by monitoring the spatial variation of the trans-scattering phase, we locally measure the phase modulation associated with the probe and the optical paths. We demonstrate numerically that a technique involving two-phase imaging of a sample with two different sized tips should allow to obtain the image the pLDOS. For this imaging method, numerical comparison with extinction probe measurement shows crucial qualitative and quantitative improvement.

  3. Scanning probe and optical tweezer investigations of biomolecular interactions

    Energy Technology Data Exchange (ETDEWEB)

    Rigby-Singleton, Shellie

    2002-07-01

    A complex array of intermolecular forces controls the interactions between and within biological molecules. The desire to empirically explore the fundamental forces has led to the development of several biophysical techniques. Of these, the atomic force microscope (AFM) and the optical tweezers have been employed throughout this thesis to monitor the intermolecular forces involved in biomolecular interactions. The AFM is a well-established force sensing technique capable of measuring biomolecular interactions at a single molecule level. However, its versatility has not been extrapolated to the investigation of a drug-enzyme complex. The energy landscape for the force induced dissociation of the DHFR-methotrexate complex was studied. Revealing an energy barrier to dissociation located {approx}0.3 nm from the bound state. Unfortunately, the AFM has a limited range of accessible loading rates and in order to profile the complete energy landscape alternative force sensing instrumentation should be considered, for example the BFP and optical tweezers. Thus, this thesis outlines the development and construction an optical trap capable of measuring intermolecular forces between biomolecules at the single molecule level. To demonstrate the force sensing abilities of the optical set up, proof of principle measurements were performed which investigate the interactions between proteins and polymer surfaces subjected to varying degrees of argon plasma treatment. Complementary data was gained from measurements performed independently by the AFM. Changes in polymer resistance to proteins as a response to changes in polymer surface chemistry were detected utilising both AFM and optical tweezers measurements. Finally, the AFM and optical tweezers were employed as ultrasensitive biosensors. Single molecule investigations of the antibody-antigen interaction between the cardiac troponin I marker and its complementary antibody, reveals the impact therapeutic concentrations of heparin

  4. Geoacoustic Inversion Based on a Vector Hydrophone Array

    Institute of Scientific and Technical Information of China (English)

    PENG Han-Shu; LI Feng-Hua

    2007-01-01

    We propose a geoacoustic inversion scheme employing a vector hydrophone array based on the fact that vector hydrophone can provide more acoustic field information than traditional pressure hydrophones. Firstly, the transmission loss of particle velocities is discussed. Secondly, the sediment sound speed is acquired by a matchedfield processing (MFP) procedure, which is the optimization in combination of the pressure field and vertical particle velocity field. Finally, the bottom attenuation is estimated from the transmission loss difference between the vertical particle velocity and the pressure. The inversion method based on the vector hydrophone array mainly has two advantages: One is that the MFP method based on vector field can decrease the uncertain estimation of the sediment sound speed. The other is that the objective function based on the transmission loss difference has good sensitivity to the sediment attenuation and the inverted sediment attenuation is independent of source level.The wlidity of the inverted parameters is examined by comparison of the numerical results with the experimentaldata.

  5. Development of a high sensitive MEMS hydrophone using PVDF

    Science.gov (United States)

    Varadan, Vijay K.; Zhu, Bei; K. A, Jose

    2002-05-01

    The design and experimental evaluation of a PVDF-based MEMS hydrophone is presented in this paper. The basic structure of the hydrophone was fabricated on a silicon wafer using standard NMOS process technology. A MOSFET with extended gate electrode was designed as the interface circuit to the sensing material, which is a piezoelectric polymer, polyvinylidene difluoride (PVDF). Acoustic impedance possessed by this piezoelectric material provides a reasonable match to water, which makes it very attractive for underwater applications. The electrical signal generated by the PVDF film was directly coupled to the gate of the MOSFET. To minimize the parasitic capacitance underneath the PVDF film and hence improve the device sensitivity, a thick photoresist was first employed as the dielectric layer under the extended gate electrode. For underwater operation, a waterproof Rho-C rubber encapsulated the hydrophone. A silicon nitride layer passivated the active device, which is a good barrier material to most mobile ions and solvents. The device after passivation also shows a lower noise level. The theoretical model developed to predict the sensitivity of the hydrophone shows a reasonable agreement between the theory and the experiment.

  6. Probing DNA with micro- and nanocapillaries and optical tweezers

    Energy Technology Data Exchange (ETDEWEB)

    Steinbock, L J; Otto, O; Skarstam, D R; Jahn, S; Chimerel, C; Gornall, J L; Keyser, U F, E-mail: ufk20@cam.ac.u [Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

    2010-11-17

    We combine for the first time optical tweezer experiments with the resistive pulse technique based on capillaries. Quartz glass capillaries are pulled into a conical shape with tip diameters as small as 27 nm. Here, we discuss the translocation of {lambda}-phage DNA which is driven by an electrophoretic force through the nanocapillary. The resulting change in ionic current indicates the folding state of single {lambda}-phage DNA molecules. Our flow cell design allows for the straightforward incorporation of optical tweezers. We show that a DNA molecule attached to an optically trapped colloid is pulled into a capillary by electrophoretic forces. The detected electrophoretic force is in good agreement with measurements in solid-state nanopores.

  7. Probing the ultimate limit of fiber-optic strain sensing.

    Science.gov (United States)

    Gagliardi, G; Salza, M; Avino, S; Ferraro, P; De Natale, P

    2010-11-19

    The measurement of relative displacements and deformations is important in many fields such as structural engineering, aerospace, geophysics, and nanotechnology. Optical-fiber sensors have become key tools for strain measurements, with sensitivity limits ranging between 10(-9) and 10(-6)ε hertz (Hz)(-1/2) (where ε is the fractional length change). We report on strain measurements at the 10(-13)ε-Hz(-1/2) level using a fiber Bragg-grating resonator with a diode-laser source that is stabilized against a quartz-disciplined optical frequency comb, thus approaching detection limits set by thermodynamic phase fluctuations in the fiber. This scheme may provide a route to a new generation of strain sensors that is entirely based on fiber-optic systems, which are aimed at measuring fundamental physical quantities; for example, in gyroscopes, accelerometers, and gravity experiments.

  8. A fiber-optic probe for particle sizing in concentrated suspensions

    Science.gov (United States)

    Dhadwal, Harbans S.; Ansari, Rafat R.; Meyer, William V.

    1991-01-01

    A fiber-optic probe employing two monomode optical fibers, one for transmitting a Gaussian laser beam to the scattering volume and the second, positioned at some backscatter angle, for receiving the scattered light is described. Performance and suitability of the system for a process control environment is assessed by studying a suspension of polystyrene latex particles over a wide range of sizes and concentrations. The results show that the probe is ideal for a process control environment in industrial and laboratory applications. Particle size is recovered, without any additional corrections for multiple light scattering, in concentrations containing up to 10 percent solids of 39-nm polystyrene latex spheres.

  9. Raman Probe Based on Optically-Poled Double-Core Fiber

    DEFF Research Database (Denmark)

    Brunetti, Anna Chiara; Margulis, Walter; Rottwitt, Karsten

    2012-01-01

    A Raman probe based on an optically-poled double-core fiber. In-fiber SHG allows for Raman spectroscopy of DMSO at 532nm when illuminating the fiber with 1064nm light. The fiber structure provides independent excitation and collection paths.......A Raman probe based on an optically-poled double-core fiber. In-fiber SHG allows for Raman spectroscopy of DMSO at 532nm when illuminating the fiber with 1064nm light. The fiber structure provides independent excitation and collection paths....

  10. Generating and probing entangled states for optical atomic clocks

    Science.gov (United States)

    Braverman, Boris; Kawasaki, Akio; Vuletic, Vladan

    2016-05-01

    The precision of quantum measurements is inherently limited by projection noise caused by the measurement process itself. Spin squeezing and more complex forms of entanglement have been proposed as ways of surpassing this limitation. In our system, a high-finesse asymmetric micromirror-based optical cavity can mediate the atom-atom interaction necessary for generating entanglement in an 171 Yb optical lattice clock. I will discuss approaches for creating, characterizing, and optimally utilizing these nonclassical states for precision measurement, as well as recent progress toward their realization. This research is supported by DARPA QuASAR, NSF, and NSERC.

  11. Electro-optic probe measurements of electric fields in plasmas

    Science.gov (United States)

    Nishiura, M.; Yoshida, Z.; Mushiake, T.; Kawazura, Y.; Osawa, R.; Fujinami, K.; Yano, Y.; Saitoh, H.; Yamasaki, M.; Kashyap, A.; Takahashi, N.; Nakatsuka, M.; Fukuyama, A.

    2017-02-01

    The direct measurements of high-frequency electric fields in a plasma bring about significant advances in the physics and engineering of various waves. We have developed an electro-optic sensor system based on the Pockels effect. Since the signal is transmitted through an optical fiber, the system has high tolerance for electromagnetic noises. To demonstrate its applicability to plasma experiments, we report the first result of measurement of the ion-cyclotron wave excited in the RT-1 magnetosphere device. This study compares the results of experimental field measurements with simulation results of electric fields in plasmas.

  12. Dynamic characterization of silicon nanowires using a terahertz optical asymmetric demultiplexer-based pump-probe scheme

    DEFF Research Database (Denmark)

    Ji, Hua; Cleary, C. S.; Dailey, J. M.;

    2012-01-01

    Dynamic phase and amplitude all-optical responses of silicon nanowires are characterized using a terahertz optical asymmetric demultiplexer (TOAD) based pump-probe scheme. Ultra-fast recovery is observed for moderate pump powers....

  13. Bases for time-resolved probing of transient carrier dynamics by optical pump-probe scanning tunneling microscopy.

    Science.gov (United States)

    Yokota, Munenori; Yoshida, Shoji; Mera, Yutaka; Takeuchi, Osamu; Oigawa, Haruhiro; Shigekawa, Hidemi

    2013-10-07

    The tangled mechanism that produces optical pump-probe scanning tunneling microscopy spectra from semiconductors was analyzed by comparing model simulation data with experimental data. The nonlinearities reflected in the spectra, namely, the excitations generated by paired laser pulses with a delay time, the logarithmic relationship between carrier density and surface photovoltage (SPV), and the effect of the change in tunneling barrier height depending on SPV, were examined along with the delay-time-dependent integration process used in measurement. The optimum conditions required to realize reliable measurement, as well as the validity of the microscopy technique, were demonstrated for the first time.

  14. Probing myocardium biomechanics using quantitative optical coherence elastography

    Science.gov (United States)

    Wang, Shang; Lopez, Andrew L.; Morikawa, Yuka; Tao, Ge; Li, Jiasong; Larina, Irina V.; Martin, James F.; Larin, Kirill V.

    2015-03-01

    We present a quantitative optical coherence elastographic method for noncontact assessment of the myocardium elasticity. The method is based on shear wave imaging optical coherence tomography (SWI-OCT), where a focused air-puff system is used to induce localized tissue deformation through a low-pressure short-duration air stream and a phase-sensitive OCT system is utilized to monitor the propagation of the induced tissue displacement with nanoscale sensitivity. The 1-D scanning of M-mode OCT imaging and the application of optical phase retrieval and mapping techniques enable the reconstruction and visualization of 2-D depth-resolved shear wave propagation in tissue with ultra-high frame rate. The feasibility of this method in quantitative elasticity measurement is demonstrated on tissue-mimicking phantoms with the estimated Young's modulus compared with uniaxial compression tests. We also performed pilot experiments on ex vivo mouse cardiac muscle tissues with normal and genetically altered cardiomyocytes. Our results indicate this noncontact quantitative optical coherence elastographic method can be a useful tool for the cardiac muscle research and studies.

  15. Atomic quantum superposition state generation via optical probing

    DEFF Research Database (Denmark)

    Nielsen, Anne Ersbak Bang; Poulsen, Uffe Vestergaard; Negretti, Antonio

    2009-01-01

    We analyze the performance of a protocol to prepare an atomic ensemble in a superposition of two macroscopically distinguishable states. The protocol relies on conditional measurements performed on a light field, which interacts with the atoms inside an optical cavity prior to detection, and we...

  16. Measurement of Rotating Blade Tip Clearance with Fibre-Optic Probe

    Energy Technology Data Exchange (ETDEWEB)

    Cao, S Z; Duan, F J; Zhang, Y G [State Key Laboratory of Measurement Technology and Instruments, Tianjin, University. Tianjin, 300072 (China)

    2006-10-15

    This paper described a tip clearance measuring system with fibre-optic probe. The system is based on a novel tip clearance sensor of optical fibre-bundle mounted on the casing, rotating speed synchronization sensor mounted on the rotating shaft, the tip clearance preamplification processing circuit followed by high speed data-acquisition unit. A novel tip clearance sensor of trifurcated optical fibre bundle was proposed and demonstrated. It is independent of material of measured surface but capacitive probe demands target conductive. Measurements can be taken under severe conditions such as ionization. Sensor circuitry and data acquisition circuit were successfully designed. With the help of Rotation synchronized sensor, all the blades can be detected in real-time. Because of fibre-optic sensor, the measuring system has commendably frequency response, which can work well in high rotating speed from 0-15000rpm.The measurement range of tip clearance is 0-3mm with 25um precision.

  17. Second harmonic generation at the probe tip for background-free near-field optical imaging.

    Science.gov (United States)

    Dong, Zhaogang; Soh, Yeng Chai

    2012-08-13

    Second harmonic generation (SHG) has been applied to reduce background signals in near-field optical imaging, but this technique is usually limited to samples with strong second-order nonlinear susceptibilities. To overcome this limitation, in this paper, we present a versatile background-free SHG configuration, where it utilizes the second-order nonlinear susceptibility of the probe which essentially functions as a near-field polarizer capable of filtering out the background signal component. In the theoretical analysis, we first model the probe-sample optical interactions at both the fundamental frequency and the second harmonic frequency by using the coupled dipole method. The theoretical model reveals that the proposed versatile background-free SHG configuration requires two conditions. The first condition is that the incident optical field must be s-polarized. The second condition is that the probe must be made of crystals from symmetry class 222, symmetry class 622, symmetry class 422, symmetry class 42m, symmetry class 43m or symmetry class 23. To demonstrate the effectiveness of the proposed versatile background-free SHG configuration, a probe made of deuterated potassium dideuterium phosphate (DKDP) crystal from symmetry class 42m is analyzed numerically. It is shown that when imaging samples with negligible second-order nonlinear susceptibilities, the proposed background-free SHG configuration improves the imaging contrast by more than one-order of magnitude as compared to all other imaging configurations. Moreover, we also investigate the dependence of its performance on other parameters, such as the probe-sample distance, the relative size between probe and sample, and the tilt angle of probe crystal. It is believed that the proposed configuration could be widely used to achieve high contrast near-field optical imaging.

  18. Asteroid (4179) Toutatis size determination via optical images observed by the Chang'e-2 probe

    Science.gov (United States)

    Liu, P.; Huang, J.; Zhao, W.; Wang, X.; Meng, L.; Tang, X.

    2014-07-01

    This work is a physical and statistical study of the asteroid (4179) Toutatis using the optical images obtained by a solar panel monitor of the Chang'e-2 probe on Dec. 13, 2012 [1]. In the imaging strategy, the camera is focused at infinity. This is specially designed for the probe with its solar panels monitor's principle axis pointing to the relative velocity direction of the probe and Toutatis. The imaging strategy provides a dedicated way to resolve the size by multi-frame optical images. The inherent features of the data are: (1) almost no rotation was recorded because of the 5.41-7.35 Earth-day rotation period and the small amount of elapsed imaging time, only minutes, make the object stay in the images in a fixed position and orientation; (2) the sharpness of the upper left boundary and the vagueness of lower right boundary resulting from the direction of SAP (Sun-Asteroid-Probe angle) cause a varying accuracy in locating points at different parts of Toutatis. A common view is that direct, accurate measurements of asteroid shapes, sizes, and pole positions are now possible for larger asteroids that can be spatially resolved using the Hubble Space Telescope or large ground-based telescopes equipped with adaptive optics. For a quite complex planetary/asteroid probe study, these measurements certainly need continuous validation via a variety of ways [2]. Based on engineering parameters of the probe during the fly-by, the target spatial resolving and measuring procedures are described in the paper. Results estimated are optical perceptible size on the flyby epoch under the solar phase angles during the imaging. It is found that the perceptible size measured using the optical observations and the size derived from the radar observations by Ostro et al.~in 1995 [3], are close to one another.

  19. Design and simulation of MEMS vector hydrophone with reduced cross section based meander beams

    Science.gov (United States)

    Kumar, Manoj; Dutta, S.; Pal, Ramjay; Jain, K. K.; Gupta, Sudha; Bhan, R. K.

    2016-04-01

    MEMS based vector hydrophone is being one of the key device in the underwater communications. In this paper, we presented a bio-inspired MEMS vector hydrophone. The hydrophone structure consists of a proof mass suspended by four meander type beams with reduced cross-section. Modal patterns of the structure were studied. First three modal frequencies of the hydrophone structure were found to be 420 Hz, 420 Hz and 1646 Hz respectively. The deflection and stress of the hydrophone is found have linear behavior in the 1 µPa - 1Pa pressure range.

  20. Development of an Optically Modulated Scatterer Probe for a Near-Field Measurement System

    Science.gov (United States)

    2016-09-08

    proportional to the gain of the AUT after normalizing by the antenna pattern of the known receiver. If the scattering strength of the probe is modulated...optical power until no change was observed. The real and imaginary components of the impedance for the PDA photodiode with no light ( dark ) and at various...GHz there was a change in impedance between the dark (off) and maximum optical power (on) states of 40 Ohm in the real component and 80 Ohm in the

  1. Adapting an optical nanoantenna for high E-field probing applications to a waveguided optical waveguide (WOW)

    DEFF Research Database (Denmark)

    Rindorf, Lars Henning; Glückstad, Jesper

    2013-01-01

    light wavelength while admitting other wavelengths of light which address certain functionalities, e.g. drug release, in the WOW. In particular, we study a bow-tie optical nano-antenna to circular dielectric waveguides in aqueous environments. It is shown with finite element computer simulations......In the current work we intend to use the optical nano-antenna to include various functionalities for the recently demonstrated waveguided optical waveguide (WOW) by Palima et al. (Optics Express 2012). Specifically, we intend to study a WOW with an optical nano-antenna which can block the guiding...... that the nanoantenna can be made to operate in a bandstop mode around its resonant wavelength where there is a very high evanescent strong electrical probing field close to the antennas, and additionally the fluorescence or Raman excitations will be be unpolluted by stray light from the WOW due to the band...

  2. Common path ball lens probe for optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Singh, Kanwarpal; Yamada, Daisuke; Tearney, Guillermo J.

    2016-02-01

    Background: Common path probes are highly desirable for optical coherence tomography (OCT) as they reduce system complexity and cost. In this work we report an all-fiber common path side viewing monolithic probe for coronary artery imaging. Methods: Our common path probe was designed for spectrometer based Fourier domain OCT at 1310 nm wavelength. Light from the fiber expands in the coreless fiber region and then focussed by the ball lens. Reflection from ball lens-air interface served as reference signal. The monolithic ball lens probe was assembled within a 560 µmouter diameter drive shaft which was attached to a rotary junction. The drive shaft was placed inside an outer, transparent sheath of 800 µm diameter. Results: With a source input power of 25 mW, we could achieve sensitivity of 100.5 dB. The axial resolution of the system was found to be 15.6 µm in air and the lateral resolution (full width half maximum) was approximately 49 µm. As proof of principal, images of skin acquired using this probe demonstrated clear visualization of the stratum corneum, epidermis, and papillary dermis, along with sweat ducts. Conclusion: In this work we have demonstrated a monolithic, ball lens common, path probe for OCT imaging. The designed ball lens probe is easy to fabricate using a laser splicer. Based on the features and capability of common path probes to provide a simpler solution for OCT, we believe that this development will be an important enhancement for certain types of catheters.

  3. CTU Optical probes for liquid phase detection in the 1000 MW steam turbine

    Directory of Open Access Journals (Sweden)

    Kolovratník Michal

    2015-01-01

    Full Text Available The aim of this paper is to introduce the measurement capacity of a new generation of CTU’s optical probes to determine the liquid phase distribution in steam turbines and other energy systems. At the same time the paper presents the first part of the results concerning output wetness achieved through the use of experimental research performed with the probes in a new low pressure (LP part of the steam turbine 1000MW in the Temelin nuclear power plant (ETE. Two different probes were used. A small size extinction probe with a diameter of 25mm which was developed for measuring in a wider range of turbines in comparison with the previous generation with a diameter of 50mm. The second probe used was a photogrammetric probe developed to observe the coarse droplets. This probe is still under development and this measurement was focused on verifying the capabilities of the probe. The data processing technique is presented together with yielded examples of the wetness distribution along the last blade of the 1000MW steam turbine. The experimental measurement was done in cooperation with Doosan Škoda Power s.r.o. (DSP.

  4. Optical probing of sodium dynamics in neurons and astrocytes.

    Science.gov (United States)

    Lamy, Christophe M; Chatton, Jean-Yves

    2011-09-15

    Changes in intracellular Na(+) concentration underlie essential neurobiological processes, but few reliable tools exist for their measurement. Here we characterize a new synthetic Na(+)-sensitive fluorescent dye, Asante Natrium Green (ANG), with unique properties. This indicator was excitable in the visible spectrum and by two-photon illumination, suffered little photobleaching and located to the cytosol were it remained for long durations without noticeable unwanted effects on basic cell properties. When used in brain tissue, ANG yielded a bright fluorescent signal during physiological Na(+) responses both in neurons and astrocytes. Synchronous electrophysiological and fluorometric recordings showed that ANG produced accurate Na(+) measurement in situ. This new Na(+) indicator opens innovative ways of probing neuronal circuits.

  5. Optical probing of surfaces irradiated in a solar furnace

    Energy Technology Data Exchange (ETDEWEB)

    Tschudi, H.R.; Schubnell, M.; Mueller, C. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1996-07-22

    Endothermic chemical reactions taking place at temperatures above 700{sup o}C are candidates for the utilization of solar energy in highly concentrating solar furnaces. Special interest is focussed onto the question whether light drives chemical reactions differently than heat. One possible effect of irradiation might be a decrease of the reaction temperature. To observe such an effect it is crucial to monitor the temperature, the irradiation, and the chemical reaction of the sample under irradiation. In this paper, we present a method by which the temperature, the irradiance, and the reflectance of an irradiated sample can be measured simultaneously. The spectral reflectivity which necessarily must be known for a radiometric temperature determination serves in this scheme also as a probe for chemical or structural changes. We first outline the computational background of the method. We then present laboratory measurements showing the reflectivity changes associated with the oxidation of magnetite. (author) 5 figs., 14 refs.

  6. Facilitation at single synapses probed with optical quantal analysis.

    Science.gov (United States)

    Oertner, Thomas G; Sabatini, Bernardo L; Nimchinsky, Esther A; Svoboda, Karel

    2002-07-01

    Many synapses can change their strength rapidly in a use-dependent manner, but the mechanisms of such short-term plasticity remain unknown. To understand these mechanisms, measurements of neurotransmitter release at single synapses are required. We probed transmitter release by imaging transient increases in [Ca(2+)] mediated by synaptic N-methyl-D-aspartate receptors (NMDARs) in individual dendritic spines of CA1 pyramidal neurons in rat brain slices, enabling quantal analysis at single synapses. We found that changes in release probability, produced by paired-pulse facilitation (PPF) or by manipulation of presynaptic adenosine receptors, were associated with changes in glutamate concentration in the synaptic cleft, indicating that single synapses can release a variable amount of glutamate per action potential. The relationship between release probability and response size is consistent with a binomial model of vesicle release with several (>5) independent release sites per active zone, suggesting that multivesicular release contributes to facilitation at these synapses.

  7. Tapered Optical Fiber Probe Assembled with Plasmonic Nanostructures for Surface-Enhanced Raman Scattering Application.

    Science.gov (United States)

    Huang, Zhulin; Lei, Xing; Liu, Ye; Wang, Zhiwei; Wang, Xiujuan; Wang, Zhaoming; Mao, Qinghe; Meng, Guowen

    2015-08-12

    Optical fiber-Raman devices integrated with plasmonic nanostructures have promising potentials for in situ probing remote liquid samples and biological samples. In this system, the fiber probe is required to simultaneously demonstrate stable surface enhanced Raman scattering (SERS) signals and high sensitivity toward the target species. Here we demonstrate a generic approach to integrate presynthesized plasmonic nanostructures with tapered fiber probes that are prepared by a dipping-etching method, through reversed electrostatic attraction between the silane couple agent modified silica fiber probe and the nanostructures. Using this approach, both negatively and positively charged plasmonic nanostructures with various morphologies (such as Au nanosphere, Ag nanocube, Au nanorod, Au@Ag core-shell nanorod) can be stably assembled on the tapered silica fiber probes. Attributed to the electrostatic force between the plasmonic units and the fiber surface, the nanostructures do not disperse in liquid samples easily, making the relative standard deviation of SERS signals as low as 2% in analyte solution. Importantly, the detection sensitivity of the system can be optimized by adjusting the cone angle (from 3.6° to 22°) and the morphology of nanostructures assembled on the fiber. Thus, the nanostructures-sensitized optical fiber-Raman probes show great potentials in the applications of SERS-based environmental detection of liquid samples.

  8. Amyloid Fibril-Induced Structural and Spectral Modifications in the Thioflavin-T Optical Probe

    DEFF Research Database (Denmark)

    Murugan, N. Arul; Olsen, Jógvan Magnus Haugaard; Kongsted, Jacob;

    2013-01-01

    Motivated by future possibilities to design target molecules for fibrils with diagnostic or therapeutic capability related to amyloidosis diseases, we investigate in this work the dielectric nature of amyloid fibril microenvironments in different binding sites using an optical probe, thioflavin-T...

  9. Inducing spin-dependent tunneling to probe magnetic correlations in optical lattices

    DEFF Research Database (Denmark)

    Pedersen, Kim-Georg; Andersen, Brian; Syljuåsen, Olav;

    2012-01-01

    We suggest a simple experimental method for probing antiferromagnetic spin correlations of two-component Fermi gases in optical lattices. The method relies on a spin selective Raman transition to excite atoms of one spin species to their first excited vibrational mode where the tunneling is large...

  10. Method for probing the orbital angular momentum of optical vortices in electromagnetic waves from astronomical objects.

    Science.gov (United States)

    Berkhout, Gregorius C G; Beijersbergen, Marco W

    2008-09-05

    We present an efficient method for probing the orbital angular momentum of optical vortices of arbitrary sizes. This method, based on a multipoint interferometer, has its most important application in measuring the orbital angular momentum of light from astronomical sources, opening the way to interesting new astrophysics. We demonstrate its viability by measuring the orbital angular momentum of Laguerre-Gaussian laser beams.

  11. A Tuning Fork with a Short Fibre Probe Sensor for a Near-FieldScanning Optical Microscope

    Institute of Scientific and Technical Information of China (English)

    王沛; 鲁拥华; 章江英; 明海; 谢建平; 黄建文; 高宗圣; 蔡定平

    2002-01-01

    We report on a tapping-mode tuning fork with a short fibre probe sensor for a near-field scanning optical microscope. The method demonstrates how to fabricate the short fibre probe. This tapping-mode tuning fork with a short fibre probe can provide stable and high Q at the tapping frequency of the tuning fork, and can give high-quality near-field scanning optical microscope and atomic force microscope images of samples. We present the results of using the tapping-mode tuning fork with a short fibre probe sensor for a near-field scanning optical microscope performed on an eight-channel silica waveguide.

  12. Probing vacuum birefringence using x-ray free electron and optical high-intensity lasers

    CERN Document Server

    Karbstein, Felix

    2016-01-01

    Vacuum birefringence is one of the most striking predictions of strong field quantum electrodynamics: Probe photons traversing a strong field region can indirectly sense the applied "pump" electromagnetic field via quantum fluctuations of virtual charged particles which couple to both pump and probe fields. This coupling is sensitive to the field alignment and can effectively result in two different indices of refraction for the probe photon polarization modes giving rise to a birefringence phenomenon. In this article we perform a dedicated theoretical analysis of the proposed discovery experiment of vacuum birefringence at a x-ray free electron laser/optical high-intensity laser facility. Describing both pump and probe laser pulses realistically in terms of their macroscopic electromagnetic fields, we go beyond previous analyses by accounting for various effects not considered before in this context. Our study facilitates stringent quantitative predictions and optimizations of the signal in an actual experim...

  13. Probing vacuum birefringence using x-ray free electron and optical high-intensity lasers

    Science.gov (United States)

    Karbstein, Felix; Sundqvist, Chantal

    2016-07-01

    Vacuum birefringence is one of the most striking predictions of strong field quantum electrodynamics: Probe photons traversing a strong field region can indirectly sense the applied "pump" electromagnetic field via quantum fluctuations of virtual charged particles which couple to both pump and probe fields. This coupling is sensitive to the field alignment and can effectively result in two different indices of refraction for the probe photon polarization modes giving rise to a birefringence phenomenon. In this article, we perform a dedicated theoretical analysis of the proposed discovery experiment of vacuum birefringence at an x-ray free electron laser/optical high-intensity laser facility. Describing both pump and probe laser pulses realistically in terms of their macroscopic electromagnetic fields, we go beyond previous analyses by accounting for various effects not considered before in this context. Our study facilitates stringent quantitative predictions and optimizations of the signal in an actual experiment.

  14. All-optical pulse-echo ultrasound probe for intravascular imaging (Conference Presentation)

    Science.gov (United States)

    Colchester, Richard J.; Noimark, Sacha; Mosse, Charles A.; Zhang, Edward Z.; Beard, Paul C.; Parkin, Ivan P.; Papakonstantinou, Ioannis; Desjardins, Adrien E.

    2016-02-01

    High frequency ultrasound probes such as intravascular ultrasound (IVUS) and intracardiac echocardiography (ICE) catheters can be invaluable for guiding minimally invasive medical procedures in cardiology such as coronary stent placement and ablation. With current-generation ultrasound probes, ultrasound is generated and received electrically. The complexities involved with fabricating these electrical probes can result in high costs that limit their clinical applicability. Additionally, it can be challenging to achieve wide transmission bandwidths and adequate wideband reception sensitivity with small piezoelectric elements. Optical methods for transmitting and receiving ultrasound are emerging as alternatives to their electrical counterparts. They offer several distinguishing advantages, including the potential to generate and detect the broadband ultrasound fields (tens of MHz) required for high resolution imaging. In this study, we developed a miniature, side-looking, pulse-echo ultrasound probe for intravascular imaging, with fibre-optic transmission and reception. The axial resolution was better than 70 microns, and the imaging depth in tissue was greater than 1 cm. Ultrasound transmission was performed by photoacoustic excitation of a carbon nanotube/polydimethylsiloxane composite material; ultrasound reception, with a fibre-optic Fabry-Perot cavity. Ex vivo tissue studies, which included healthy swine tissue and diseased human tissue, demonstrated the strong potential of this technique. To our knowledge, this is the first study to achieve an all-optical pulse-echo ultrasound probe for intravascular imaging. The potential for performing all-optical B-mode imaging (2D and 3D) with virtual arrays of transmit/receive elements, and hybrid imaging with pulse-echo ultrasound and photoacoustic sensing are discussed.

  15. Handheld scanning probes for optical coherence tomography: developments, applications, and perspectives

    Science.gov (United States)

    Duma, V.-F.; Demian, D.; Sinescu, C.; Cernat, R.; Dobre, G.; Negrutiu, M. L.; Topala, F. I.; Hutiu, Gh.; Bradu, A.; Podoleanu, A. G.

    2016-03-01

    We present the handheld scanning probes that we have recently developed in our current project for biomedical imaging in general and for Optical Coherence Tomography (OCT) in particular. OCT is an established, but dynamic imagistic technique based on laser interferometry, which offers micrometer resolutions and millimeters penetration depths. With regard to existing devices, the newly developed handheld probes are simple, light and relatively low cost. Their design is described in detail to allow for the reproduction in any lab, including for educational purposes. Two probes are constructed almost entirely from off-the-shelf components, while a third, final variant is constructed with dedicated components, in an ergonomic design. The handheld probes have uni-dimensional (1D) galvanometer scanners therefore they achieve transversal sections through the biological sample investigated - in contrast to handheld probes equipped with bi-dimensional (2D) scanners that can also achieve volumetric (3D) reconstructions of the samples. These latter handheld probes are therefore also discussed, as well as the possibility to equip them with galvanometer 2D scanners or with Risley prisms. For galvanometer scanners the optimal scanning functions studied in a series of previous works are pointed out; these functions offer a higher temporal efficiency/duty cycle of the scanning process, as well as artifact-free OCT images. The testing of the handheld scanning probes in dental applications is presented, for metal ceramic prosthesis and for teeth.

  16. Characterisation of a fibre optic Raman probe within a hypodermic needle.

    Science.gov (United States)

    Iping Petterson, Ingeborg E; Day, John C C; Fullwood, Leanne M; Gardner, Benjamin; Stone, Nick

    2015-11-01

    We demonstrate the first use of a multifibre Raman probe that fits inside the bore of a hypodermic needle. A Raman probe containing multiple collection fibres provides improved signal collection efficiency in biological samples compared with a previous two-fibre design. Furthermore, probe performance (signal-to-noise ratios) compared favourably with the performance achieved in previous Raman microscope experiments able to distinguish between benign lymph nodes, primary malignancies in lymph nodes and secondary malignancies in lymph nodes. The experimental measurements presented here give an indication of the sampling volume of the Raman needle probe in lymphoid tissues. Liquid tissue phantoms were used that contained scattering medium encompassing a range of scattering properties similar to those of a variety of tissue types, including lymph node tissues. To validate the appropriateness of the phantoms, the sampling depth of the probe was also measured in excised lymph node tissue. More than 50 % of Raman photons collected were found to originate from between the tip of the needle and a depth of 500 μm into the tissue. The needle probe presented here achieves spectral quality comparable to that in numerous studies previously demonstrating Raman disease discrimination. It is expected that this approach could achieve targeted subcutaneous tissue measurements and be viable for use for the in vivo Raman diagnostics of solid organs located within a few centimetres below the skin's surface. Graphical Abstract Schematic of multi-fibre Raman needle probe with disposible tips and proximal optical filtration.

  17. Recent Advances in the Design of Electro-Optic Sensors for Minimally Destructive Microwave Field Probing

    Directory of Open Access Journals (Sweden)

    John F. Whitaker

    2011-01-01

    Full Text Available In this paper we review recent design methodologies for fully dielectric electro-optic sensors that have applications in non-destructive evaluation (NDE of devices and materials that radiate, guide, or otherwise may be impacted by microwave fields. In many practical NDE situations, fiber-coupled-sensor configurations are preferred due to their advantages over free-space bulk sensors in terms of optical alignment, spatial resolution, and especially, a low degree of field invasiveness. We propose and review five distinct types of fiber-coupled electro-optic sensor probes. The design guidelines for each probe type and their performances in absolute electric-field measurements are compared and summarized.

  18. Micro reflectance difference techniques: Optical probes for surface exploration

    Energy Technology Data Exchange (ETDEWEB)

    Lastras-Martinez, L.F.; Del Pozo-Zamudio, O.; Herrera-Jasso, R.; Ulloa-Castillo, N.A.; Balderas-Navarro, R.E.; Ortega-Gallegos, J.; Lastras-Martinez, A. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000 San Luis Potosi, S.L.P. (Mexico)

    2012-06-15

    Micro reflectance difference spectroscopy ({mu}-RDS) is a promising tool for the in-situ and ex-situ characterization of semiconductors surfaces and interfaces. We discuss and compare two different approaches used to measure {mu}-RD spectra. One is based on a charge-coupled device (CCD) camera, while the other uses a laser and a XY translation stage. To show the performance of these systems, we have measured surface optical anisotropies of GaSb(001) sample on which anisotropic strains have been generated by preferential mechanical polishing along [110] and [1 anti 10] directions. The spectrometers are complementary and the selection of one of them depends on the sample to be investigated and on experimental conditions. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Optical pump-probe microscopy for biomedicine and art conservation

    Science.gov (United States)

    Fischer, Martin

    2013-03-01

    Nonlinear optical microscopy can provide contrast in highly heterogeneous media and a wide range of applications has emerged, primarily in biology, medicine, and materials science. Compared to linear microscopy methods, the localized nature of nonlinear interactions leads to high spatial resolution, optical sectioning, and larger possible imaging depth in scattering media. However, nonlinear contrast (other than fluorescence, harmonic generation or CARS) is generally difficult to measure because it is overwhelmed by the large background of detected illumination light. This background can be suppressed by using femtosecond pulse or pulse train shaping to encode nonlinear interactions in background-free regions of the frequency spectrum. We have developed this shaping technology to study novel intrinsic structural and molecular contrast in biological tissue, generally using less power than a laser pointer. For example we have recently been able to sensitively measure detailed transient absorption dynamics of melanin sub-types in a variety of skin lesions, showing clinically relevant differences of melanin type and distribution between cancerous and benign tissue.[1] Recently we have also applied this technology to paint samples and to historic artwork in order to provide detailed, depth-resolved pigment identification. Initial studies in different inorganic and organic pigments have shown a rich and pigment-specific nonlinear absorption signature.[2] Some pigments, for example lapis lazuli (natural ultramarine), even show marked differences in signal depending on its geographic origin and on age, demonstrating the potential of this technique to determine authenticity, provenance, technology of manufacture, or state of preservation of historic works of art.

  20. Hand-held probe based optical imaging system towards breast cancer diagnosis

    Science.gov (United States)

    Ge, Jiajia; Jayachandran, Bhavani; Regalado, Steven; Zhu, Banghe; Godavarty, Anuradha

    2007-02-01

    Near-infrared (NIR) optical imaging is an emerging noninvasive modality for breast cancer diagnosis. However, the currently available optical imaging systems towards tomography studies are limited either by instrument portability, patient comfort, or flexibility to image any given tissue volume. Herein, a hand-held based optical imaging system is developed such that it can possibly overcome some of the above limitations. The unique features of the hand-held optical probe are: (i) to perform simultaneous multiple point illumination and detection, thus decreasing the total imaging time and improving the overall signal strength; (ii) to adapt to the contour of tissue surface, thus decreasing the leakage of excitation and emission signal at contact surface; and (iii) to obtain trans-illumination measurements apart from reflectance measurements, thus improving the depth information. The increased detected signal strength as well as total interrogated tissue volume is demonstrated by simulation studies (i.e. forward model) over a 5×10×10 cc slab phantom. The appropriate number and layout of the source and detection points on the probe head is determined and the hand-held optical probe is developed. A frequency-domain ICCD (intensified charge coupled device) detection system, which allows simultaneous multiple points detection, is developed and coupled to the hand-held probe in order to perform fluorescence-enhanced optical imaging of tissue phantoms. In the future, imaging of homogenous liquid phantoms will be used for the assessment of this hand-held system, followed by extensive imaging studies on different phantoms types under various experimental conditions.

  1. Process for Assembly of Multimode Hydrophone Ceramic Stack

    Science.gov (United States)

    2016-09-20

    hydrophone 10 includes tangentially-poled ceramic (lead- zirconate titanate) rings 12, a Delrin washers 14, a LC-800 washers 16, 26 AWG insulated wire ...18, a stainless steel flange 20, an end cap 22, 30 AWG uninsulated bus wire 24, solder joints 26, ¼-28 socket head screw 28, and a phenolic feed...pressure waves. [0058] The washers 104 are made from Delrin. Delrin is a nylon -like material that can be easily machined yet is rigid enough to provide

  2. Erbium-doped fiber lasers as deep-sea hydrophones

    Energy Technology Data Exchange (ETDEWEB)

    Bagnoli, P.E. [Dipartimento di Ingegneria dell' Informazione University of Pisa, Via Diotisalvi, Pisa 56100 (Italy); Istituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, Pisa 56127 (Italy); Beverini, N. [Istituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, Pisa 56127 (Italy); Dipartimento di Fisica ' E.Fermi' University of Pisa, Largo Pontecorvo 3, 56127 (Italy); Bouhadef, B. [Istituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, Pisa 56127 (Italy); Dipartimento di Fisica ' E.Fermi' University of Pisa, Largo Pontecorvo 3, 56127 (Italy); Castorina, E. [Istituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, Pisa 56127 (Italy); Dipartimento di Fisica ' E.Fermi' University of Pisa, Largo Pontecorvo 3, 56127 (Italy); Falchini, E. [Istituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, Pisa 56127 (Italy); Dipartimento di Fisica ' E.Fermi' University of Pisa, Largo Pontecorvo 3, 56127 (Italy); Falciai, R. [Istituto di Fisica Applicata ' Nello Carrara' , IFAC-CNR, Florence (Italy); Flaminio, V. [Istituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, Pisa 56127 (Italy); Dipartimento di Fisica ' E.Fermi' University of Pisa, Largo Pontecorvo 3, 56127 (Italy); Maccioni, E. [Istituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, Pisa 56127 (Italy) and Dipartimento di Fisica ' E.Fermi' University of Pisa, Largo Pontecorvo 3, 56127 (Italy)]. E-mail: maccioni@df.unipi.it; Morganti, M. [Istituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, Pisa 56127 (Italy); Dipartimento di Fisica ' E.Fermi' University of Pisa, Largo Pontecorvo 3, 56127 (Italy); Sorrentino, F. [Dipartimento di Fisica ' E.Fermi' University of Pisa, Largo Pontecorvo 3, 56127 (Italy); Stefani, F. [Dipartimento di Ingegneria dell' Informazione University of Pisa, Via Diotisalvi, Pisa 56100 (Italy); Trono, C. [Dipartimento di Fisica ' E.Fermi' University of Pisa, Largo Pontecorvo 3, 56127 (Italy); Istituto di Fisica Applicata ' Nello Carrara' , IFAC-CNR, Florence (Italy)

    2006-11-15

    The present work describes the development of a hydrophone prototype for deep-sea acoustic detection. The base-sensitive element is a single-mode erbium-doped fiber laser. The high sensitivity of these sensors makes them particularly suitable for a wide range of deep-sea acoustic applications, including geological and marine mammals surveys and above all as acoustic detectors in under-water telescopes for high-energy neutrinos.

  3. Fiber laser hydrophone as possible detector of UHE neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Maccioni, E. [Istituto Nazionale di Fisica Nucleare, Pisa, Largo Pontecorvo 3, 56127 (Italy) and Dipartimento di Fisica, ' E.Fermi' University of Pisa, Pisa, Largo Pontecorvo 3, 56127 (Italy)]. E-mail: maccioni@df.unipi.it; Bagnoli, P.E. [Dipartimento di Ingegneria dell' Informazione, University of Pisa, Pisa, Via Diotisalvi, 56100 (Italy); Istituto Nazionale di Fisica Nucleare, Pisa, Largo Pontecorvo 3, 56127 (Italy); Beverini, N. [Istituto Nazionale di Fisica Nucleare, Pisa, Largo Pontecorvo 3, 56127 (Italy); Dipartimento di Fisica, ' E.Fermi' University of Pisa, Pisa, Largo Pontecorvo 3, 56127 (Italy); Bouhadef, B. [Istituto Nazionale di Fisica Nucleare, Pisa, Largo Pontecorvo 3, 56127 (Italy); Dipartimento di Fisica, ' E.Fermi' University of Pisa, Pisa, Largo Pontecorvo 3, 56127 (Italy); Castorina, E. [Istituto Nazionale di Fisica Nucleare, Pisa, Largo Pontecorvo 3, 56127 (Italy); Dipartimento di Fisica, ' E.Fermi' University of Pisa, Pisa, Largo Pontecorvo 3, 56127 (Italy); Falchini, E. [Istituto Nazionale di Fisica Nucleare, Pisa, Largo Pontecorvo 3, 56127 (Italy); Dipartimento di Fisica, ' E.Fermi' University of Pisa, Pisa, Largo Pontecorvo 3, 56127 (Italy); Falciai, R. [Istituto di Fisica Applicata ' Nello Carrara' , IFAC-CNR, Florence (Italy); Flaminio, V. [Istituto Nazionale di Fisica Nucleare, Pisa, Largo Pontecorvo 3, 56127 (Italy); Dipartimento di Fisica, ' E.Fermi' University of Pisa, Pisa, Largo Pontecorvo 3, 56127 (Italy); Morganti, M. [Istituto Nazionale di Fisica Nucleare, Pisa, Largo Pontecorvo 3, 56127 (Italy); Dipartimento di Fisica, ' E.Fermi' University of Pisa, Pisa, Largo Pontecorvo 3, 56127 (Italy); Stefani, F. [Dipartimento di Ingegneria dell' Informazione, University of Pisa, Pisa, Via Diotisalvi, 56100 (Italy); Trono, C. [Dipartimento di Fisica, ' E.Fermi' University of Pisa, Pisa, Largo Pontecorvo 3, 56127 (Italy); Istituto di Fisica Applicata ' Nello Carrara' , IFAC-CNR, Florence (Italy)

    2007-03-01

    The possibility to use a single mode erbium-doped fiber laser as hydrophone for deep sea acoustic detection is considered. The high sensitivity of these sensors, their immunity from electromagnetic fields and their faculty to work at high environmental pressure, make them particularly suitable for a wide range of deep sea acoustic applications, and in particular as acoustic detectors in under-water telescopes for high-energy neutrinos.

  4. Use of optical tweezers to probe epithelial mechanosensation

    Science.gov (United States)

    Resnick, Andrew

    2010-01-01

    Cellular mechanosensation mechanisms have been implicated in a variety of disease states. Specifically in renal tubules, the primary cilium and associated mechanosensitive ion channels are hypothesized to play a role in water and salt homeostasis, with relevant disease states including polycystic kidney disease and hypertension. Previous experiments investigating ciliary-mediated cellular mechanosensation have used either fluid flow chambers or micropipetting to elicit a biological response. The interpretation of these experiments in terms of the ``ciliary hypothesis'' has been difficult due the spatially distributed nature of the mechanical disturbance-several competing hypotheses regarding possible roles of primary cilium, glycocalyx, microvilli, cell junctions, and actin cytoskeleton exist. I report initial data using optical tweezers to manipulate individual primary cilia in an attempt to elicit a mechanotransduction response-specifically, the release of intracellular calcium. The advantage of using laser tweezers over previous work is that the applied disturbance is highly localized. I find that stimulation of a primary cilium elicits a response, while stimulation of the apical surface membrane does not. These results lend support to the hypothesis that the primary cilium mediates transduction of mechanical strain into a biochemical response in renal epithelia.

  5. SU-E-T-610: Phosphor-Based Fiber Optic Probes for Proton Beam Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Darafsheh, A; Soldner, A; Liu, H; Kassaee, A; Zhu, T; Finlay, J [Univ Pennsylvania, Philadelphia, PA (United States)

    2015-06-15

    Purpose: To investigate feasibility of using fiber optics probes with rare-earth-based phosphor tips for proton beam radiation dosimetry. We designed and fabricated a fiber probe with submillimeter resolution (<0.5 mm3) based on TbF3 phosphors and evaluated its performance for measurement of proton beam including profiles and range. Methods: The fiber optic probe with TbF3 phosphor tip, embedded in tissue-mimicking phantoms was irradiated with double scattering proton beam with energy of 180 MeV. Luminescence spectroscopy was performed by a CCD-coupled spectrograph to analyze the emission spectra of the fiber tip. In order to measure the spatial beam profile and percentage depth dose, we used singular value decomposition method to spectrally separate the phosphors ionoluminescence signal from the background Cerenkov radiation signal. Results: The spectra of the TbF3 fiber probe showed characteristic ionoluminescence emission peaks at 489, 542, 586, and 620 nm. By using singular value decomposition we found the contribution of the ionoluminescence signal to measure the percentage depth dose in phantoms and compared that with measurements performed with ion chamber. We observed quenching effect at the spread out Bragg peak region, manifested as under-responding of the signal, due to the high LET of the beam. However, the beam profiles were not dramatically affected by the quenching effect. Conclusion: We have evaluated the performance of a fiber optic probe with submillimeter resolution for proton beam dosimetry. We demonstrated feasibility of spectral separation of the Cerenkov radiation from the collected signal. Such fiber probes can be used for measurements of proton beams profile and range. The experimental apparatus and spectroscopy method developed in this work provide a robust platform for characterization of proton-irradiated nanophosphor particles for ultralow fluence photodynamic therapy or molecular imaging applications.

  6. Interferometric measurement of injection nozzles using ultra-small fiber-optical probes

    Institute of Scientific and Technical Information of China (English)

    Tilo Pfeifer; Robert Schmitt; Niels K(o)nig; Guilherme Francisco Mallmann

    2011-01-01

    The measurement of boreholes with diameters smaller than 500 pm is a demanding task that cannot be performed using state-of-the-art production metrology.In this letter,a miniaturized fiber probe with a diameter of 80 pm is presented.A probe is used for low-coherence interferometry to conduct highly precise measurements of form deviations of small boreholes.Measurements conducted in nozzles are also presented.The results prove the potential of the fiber-optical sensor for quality inspection of high-precision parts,such as injection nozzles,for common-rail diesel engines.

  7. Probing other solar systems with current and future adaptive optics

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B; Marois, C; Phillion, D; Poyneer, L; Graham, J; Zuckerman, B; Gavel, D; Veran, J; Wilhelmsen-Evans, J; Mellis, C

    2008-09-08

    Over the past decade, the study of extrasolar planets through indirect techniques--primarily Doppler measurements--has revolutionized our understanding of other solar systems. The next major step in this field will be the direct detection and characterization, via imaging and spectroscopy, of the planets themselves. To achieve this, we must separate the light from the faint planet from the extensive glare of its parent star. We pursued this goal using the current generation of adaptive optics (AO) systems on large ground-based telescopes, using infrared imaging to search for the thermal emission from young planets and developing image processing techniques to distinguish planets from telescope-induced artifacts. Our new Angular Differential Imaging (ADI) technique, which uses the sidereal rotation of the Earth and telescope, is now standard for ground-based high-contrast imaging. Although no young planets were found in our surveys, we placed the strongest limits yet on giant planets in wide orbits (>30 AU) around young stars and characterized planetary companion candidates. The imaging of planetary companions on solar-system-like scales (5-30 AU) will require a new generation of advanced AO systems that are an order of magnitude more powerful than the LLNL-built Keck AO system. We worked to develop and test the key technologies needed for these systems, including a spatially-filtered wavefront sensor, efficient and accurate wavefront reconstruction algorithms, and precision AO wavefront control at the sub-nm level. LLNL has now been selected by the Gemini Observatory to lead the construction of the Gemini Planet Imager, a $24M instrument that will be the most advanced AO system in the world.

  8. Probing other solar systems with current and future adaptive optics

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B; Marois, C; Phillion, D; Poyneer, L; Graham, J; Zuckerman, B; Gavel, D; Veran, J; Wilhelmsen-Evans, J; Mellis, C

    2008-09-08

    Over the past decade, the study of extrasolar planets through indirect techniques--primarily Doppler measurements--has revolutionized our understanding of other solar systems. The next major step in this field will be the direct detection and characterization, via imaging and spectroscopy, of the planets themselves. To achieve this, we must separate the light from the faint planet from the extensive glare of its parent star. We pursued this goal using the current generation of adaptive optics (AO) systems on large ground-based telescopes, using infrared imaging to search for the thermal emission from young planets and developing image processing techniques to distinguish planets from telescope-induced artifacts. Our new Angular Differential Imaging (ADI) technique, which uses the sidereal rotation of the Earth and telescope, is now standard for ground-based high-contrast imaging. Although no young planets were found in our surveys, we placed the strongest limits yet on giant planets in wide orbits (>30 AU) around young stars and characterized planetary companion candidates. The imaging of planetary companions on solar-system-like scales (5-30 AU) will require a new generation of advanced AO systems that are an order of magnitude more powerful than the LLNL-built Keck AO system. We worked to develop and test the key technologies needed for these systems, including a spatially-filtered wavefront sensor, efficient and accurate wavefront reconstruction algorithms, and precision AO wavefront control at the sub-nm level. LLNL has now been selected by the Gemini Observatory to lead the construction of the Gemini Planet Imager, a $24M instrument that will be the most advanced AO system in the world.

  9. Optical properties of biomimetic probes engineered from erythrocytes

    Science.gov (United States)

    Burns, Joshua M.; Saager, Rolf; Majaron, Boris; Jia, Wangcun; Anvari, Bahman

    2017-01-01

    Light-activated theranostic materials offer a potential platform for optical imaging and phototherapeutic applications. We have engineered constructs derived from erythrocytes, which can be doped with the FDA-approved near infrared (NIR) chromophore, indocyanine green (ICG). We refer to these constructs as NIR erythrocyte-mimicking transducers (NETs). Herein, we investigated the effects of changing the NETs mean diameter from micron- (≈4 μm) to nano- (≈90 nm) scale, and the ICG concentration utilized in the fabrication of NETs from 5 to 20 μM on the resulting absorption and scattering characteristics of the NETs. Our approach consisted of integrating sphere-based measurements of light transmittance and reflectance, and subsequent utilization of these measurements in an inverse adding-doubling algorithm to estimate the absorption (μ a) and reduced scattering (μ s‧) coefficients of these NETs. For a given NETs diameter, values of μ a increased over the approximate spectral band of 630-860 nm with increasing ICG concentration. Micron-sized NETs produced the highest peak value of μ a when using ICG concentrations of 10 and 20 μM, and showed increased values of μ s‧ as compared to nano-sized NETs. Spectral profiles of μ s‧ for these NETs showed a trend consistent with Mie scattering behavior for spherical objects. For all NETs investigated, changing the ICG concentration minimally affected the scattering characteristics. A Monte Carlo-based model of light distribution showed that the presence of these NETs enhanced the fluence levels within simulated blood vessels. These results provide important data towards determining the appropriate light dosimetry parameters for an intended light-based biomedical application of NETs.

  10. Design and testing of prototype handheld scanning probes for optical coherence tomography.

    Science.gov (United States)

    Demian, Dorin; Duma, Virgil-Florin; Sinescu, Cosmin; Negrutiu, Meda Lavinia; Cernat, Ramona; Topala, Florin Ionel; Hutiu, Gheorghe; Bradu, Adrian; Podoleanu, Adrian Gh

    2014-08-01

    Three simple and low-cost configurations of handheld scanning probes for optical coherence tomography have been developed. Their design and testing for dentistry applications are presented. The first two configurations were built exclusively from available off-the-shelf optomechanical components, which, to the best of our knowledge, are the first designs of this type. The third configuration includes these components in an optimized and ergonomic probe. All the designs are presented in detail to allow for their duplication in any laboratory with a minimum effort, for applications that range from educational to high-end clinical investigations. Requirements that have to be fulfilled to achieve configurations which are reliable, ergonomic-for clinical environments, and easy to build are presented. While a range of applications is possible for the prototypes developed, in this study the handheld probes are tested ex vivo with a spectral domain optical coherence tomography system built in-house, for dental constructs. A previous testing with a swept source optical coherence tomography system has also been performed both in vivo and ex vivo for ear, nose, and throat-in a medical environment. The applications use the capability of optical coherence tomography to achieve real-time, high-resolution, non-contact, and non-destructive interferometric investigations with micrometer resolutions and millimeter penetration depth inside the sample. In this study, testing the quality of the material of one of the most used types of dental prosthesis, metalo-ceramic is thus demonstrated. © IMechE 2014.

  11. Optical nanofiber integrated into an optical tweezers for particle probing and manipulation

    CERN Document Server

    Frawley, Mary C; Truong, Viet Giang; Chormaic, Sile Nic

    2014-01-01

    We present an integrated platform for particle manipulation consisting of a combined optical nanofiber and optical tweezers system. Individual silica microspheres were introduced to the nanofiber at arbitrary points using the optical tweezers, thereby producing pronounced dips in the fiber transmission. We show that such consistent and reversible transmission modulations depend on both particle and fiber diameter, and may be used as a reference point for in-situ nanofiber or particle size calibration. Particle arrays can be released from the optical tweezers onto the nanofiber and are propelled along the fiber length via guided light. We also demonstrate how the optical tweezers can be used to create a "particle jet" to feed a supply of microspheres to the nanofiber surface, forming a particle conveyor belt. This integrated optical platform provides a method for selective evanescent field manipulation of micron-sized particles and may facilitate studies of optical binding and light-particle interaction dynami...

  12. Ultra-thin and flexible endoscopy probe for optical coherence tomography based on stepwise transitional core fiber.

    Science.gov (United States)

    Lee, Jangbeom; Chae, Yugyeong; Ahn, Yeh-Chan; Moon, Sucbei

    2015-05-01

    We present an ultra-thin fiber-body endoscopy probe for optical coherence tomography (OCT) which is based on a stepwise transitional core (STC) fiber. In a minimalistic design, our probe was made of spliced specialty fibers that could be directly used for beam probing optics without using a lens. In our probe, the OCT light delivered through a single-mode fiber was efficiently expanded to a large mode field of 24 μm diameter for a low beam divergence. The size of our probe was 85 μm in the probe's diameter while operated in a 160-μm thick protective tubing. Through theoretical and experimental analyses, our probe was found to exhibit various attractive features in terms of compactness, flexibility and reliability along with its excellent fabrication simplicity.

  13. Imaging individual proteins and nanodomains on intact cell membranes with a probe-based optical antenna.

    Science.gov (United States)

    van Zanten, Thomas S; Lopez-Bosque, Maria J; Garcia-Parajo, Maria F

    2010-01-01

    Optical antennas that confine and enhance electromagnetic fields in a nanometric region hold great potential for nanobioimaging and biosensing. Probe-based monopole optical antennas are fabricated to enhance fields localized to <30 nm near the antenna apex in aqueous conditions. These probes are used under appropriate excitation antenna conditions to image individual antibodies with an unprecedented resolution of 26 +/- 4 nm and virtually no surrounding background. On intact cell membranes in physiological conditions, the obtained resolution is 30 +/- 6 nm. Importantly, the method allows individual proteins to be distinguished from nanodomains and the degree of clustering to be quantified by directly measuring physical size and intensity of individual fluorescent spots. Improved antenna geometries should lead to true live cell imaging below 10-nm resolution with position accuracy in the subnanometric range.

  14. Probing the mechanics of the complete DNA transcription cycle in real-time using optical tweezers.

    Science.gov (United States)

    Baumann, Christoph G; Cross, Stephen J

    2011-01-01

    RNA polymerase (RNAP) is a DNA-dependent motor protein that links ribonucleotide polymerization to force generation and DNA translocation through its active site, i.e., mechanical work. Single-molecule studies using optical tweezers have allowed researchers to probe the load-dependent ribonucleotide incorporation rate and processivity of both single-subunit viral and multisubunit prokaryotic and eukaryotic RNAPs engaged in transcription elongation. A single-molecule method is described here, which allows the complete transcription cycle (i.e., promoter binding, initiation, elongation and termination) to be followed in real-time using dual-trap optical tweezers and a unique "three-bead" geometry. This single-molecule transcription assay can be used to probe the mechanics of both stationary and moving RNAP-DNA complexes engaged in different stages of transcription.

  15. Brillouin optical time-domain analyzer for extended sensing range using probe dithering and cyclic coding

    Science.gov (United States)

    Iribas, Haritz; Loayssa, Alayn; Sauser, Florian; Llera, Miguel; Le Floch, Sébastien

    2017-04-01

    We present an enhanced performance Brillouin optical time-domain analysis sensor that uses dual probes waves with optical frequency modulation and cyclic coding. The frequency modulation serves to increase the probe power that can be injected in the fiber before the onset of non-local effects and noise generated by spontaneous Brillouin scattering. This leads to higher detected signal-to-noise ratio (SNR), which is further increased by the coding gain. The enhanced SNR translates to extended range for the sensor, with experiments demonstrating 1-m spatial resolution over a 164 km fiber loop with a 3-MHz Brillouin frequency shift measurement precision at the worst contrast position. In addition, we introduce a study of the power limits that can be injected in the fiber with cyclic coding before the appearance of distortions in the decoded signal.

  16. Probing the structural dynamics of proteins and nucleic acids with optical tweezers.

    Science.gov (United States)

    Ritchie, Dustin B; Woodside, Michael T

    2015-10-01

    Conformational changes are an essential feature of most molecular processes in biology. Optical tweezers have emerged as a powerful tool for probing conformational dynamics at the single-molecule level because of their high resolution and sensitivity, opening new windows on phenomena ranging from folding and ligand binding to enzyme function, molecular machines, and protein aggregation. By measuring conformational changes induced in a molecule by forces applied by optical tweezers, new insight has been gained into the relationship between dynamics and function. We discuss recent advances from studies of how structure forms in proteins and RNA, including non-native structures, fluctuations in disordered proteins, and interactions with chaperones assisting native folding. We also review the development of assays probing the dynamics of complex protein-nucleic acid and protein-protein assemblies that reveal the dynamic interactions between biomolecular machines and their substrates.

  17. Elliptical polarization of near-resonant linearly polarized probe light in optically pumped alkali metal vapor.

    Science.gov (United States)

    Li, Yingying; Wang, Zhiguo; Jin, Shilong; Yuan, Jie; Luo, Hui

    2017-02-20

    Optically pumped alkali metal atoms currently provide a sensitive solution for magnetic microscopic measurements. As the most practicable plan, Faraday rotation of linearly polarized light is extensively used in spin polarization measurements of alkali metal atoms. In some cases, near-resonant Faraday rotation is applied to improve the sensitivity. However, the near-resonant linearly polarized probe light is elliptically polarized after passing through optically pumped alkali metal vapor. The ellipticity of transmitted near-resonant probe light is numerically calculated and experimentally measured. In addition, we also analyze the negative impact of elliptical polarization on Faraday rotation measurements. From our theoretical estimate and experimental results, the elliptical polarization forms an inevitable error in spin polarization measurements.

  18. Laser-based technology of scanning near-field optical probes fabrication: study of kinetics and progress of measuring

    Science.gov (United States)

    Veiko, Vadim P.; Kalachev, Alexey I.; Kaporsky, Lev N.; Volkov, Sergey A.; Voznesensky, Nikolay B.

    2003-02-01

    Basic principles of laser assisted process of fiber etching for scanning near-field optical (SNO) probes formation and control technique are presented. The thermal and temporal regimes are considered in order to provide stable reproducibility and high quality of a tapered end of the optical fiber. Problems of adequate definition of the scanning imaging properties of a SNO probe are discussed. Thus an optical method of far-field registration and processing together with a new autoelectronic emission method are considered for solution of the task of a subwavelength SNO probe aperture measurement and estimation of its apparatus function.

  19. A New Pumping-Probing Scheme for the Optically Pumped Cesium Beam Frequency Standard

    Institute of Scientific and Technical Information of China (English)

    陈景标; 朱程锦; 王凤芝; 杨东海

    2001-01-01

    A new pumping-probing scheme for the optically pumped cesium beam frequency standard has been experimentally tested in our laboratory. The stability of the optically pumped cesium beam frequency standard was measured by comparing its 10 MHz output with an HP5071A commercial cesium atomic clock. The result shows that the frequency stability for the 1 s and 30000s sample times are 1.2 × 10-11 and 3.7 × 10-13, respectively. It was proved that the new pumping scheme works well.

  20. Reciprocity theory of apertureless scanning near-field optical microscopy with point-dipole probes.

    Science.gov (United States)

    Esslinger, Moritz; Vogelgesang, Ralf

    2012-09-25

    Near-field microscopy offers the opportunity to reveal optical contrast at deep subwavelength scales. In scanning near-field optical microscopy (SNOM), the diffraction limit is overcome by a nanoscopic probe in close proximity to the sample. The interaction of the probe with the sample fields necessarily perturbs the bare sample response, and a critical issue is the interpretation of recorded signals. For a few specific SNOM configurations, individual descriptions have been modeled, but a general and intuitive framework is still lacking. Here, we give an exact formulation of the measurable signals in SNOM which is easily applicable to experimental configurations. Our results are in close analogy with the description Tersoff and Hamann have derived for the tunneling currents in scanning tunneling microscopy. For point-like scattering probe tips, such as used in apertureless SNOM, the theory simplifies dramatically to a single scalar relation. We find that the measured signal is directly proportional to the field of the coupled tip-sample system at the position of the tip. For weakly interacting probes, the model thus verifies the empirical findings that the recorded signal is proportional to the unperturbed field of the bare sample. In the more general case, it provides guidance to an intuitive and faithful interpretation of recorded images, facilitating the characterization of tip-related distortions and the evaluation of novel SNOM configurations, both for aperture-based and apertureless SNOM.

  1. Fabrication of integrated optic fibre tip for micron CMMs touch trigger probe application

    Science.gov (United States)

    Ji, H.; Hsu, H. Y.; Chua, J.; Kong, L. X.; Wedding, A. B.; She, M.; Lin, G. C. I.; Fan, K. C.

    2005-12-01

    In the last decade the general miniaturisation of complex products has lead to an increased importance of high precision machining and assembly. Together with increasing precision of products, the need for highly accurate dimensional inspection increases. CMMs (Coordinate Measuring Machines), as a versatile and widespread dimensional metrology tool, can efficiently perform complex measurement with a resolution of about 0.1μm and a repeatability of about 0.3μm. The existing probes for CMMs tend to be very bulky and result in high probing forces for geometrical measurements of high accuracy on small parts. In this paper, an economical flexible method, which is based on optical fibre splicer, is proposed to fabricate an integrated micro scale silicon probe with spherical tip for micron CMMs. Based on Taguchi method, a combination of optimised process parameters has been obtained to control the fabrication conditions that will ensure the manufacturing of tips of a high and consistent quality. With proper control of the process parameters, an optic fibre probe tip with the diameter dimension in the range of 200 to 400μm is achieved and there is a great potential to fabricate a smaller tip with a diameter of 50-100μm in the future.

  2. Velocity anisotropy effect in pump-probe spectra of cesium in a micrometric thickness optical cell

    Science.gov (United States)

    Ghosh, P. N.; Mitra, S.; Ray, B.; Krasteva, A.; Slavov, D.; Todorov, P.; Cartaleva, S.

    2015-01-01

    The pump-probe spectra in a cell of micrometric thickness containing cesium vapor are reported. The line shape and nonlinear features observed in the case of fluorescence in the direction parallel to the cell windows and the transmission spectra observed along the propagation direction of the probe beam show considerable differences in the spectral profiles. We observed Electromagnetically Induced Transparency (EIT) and enhanced Velocity Selective Optical Pumping (VSOP) signals. Atoms moving nearly parallel to the windows and perpendicular to the collinear pump and probe beams will see much lower Doppler shift of incident frequencies and hence will lead to considerable narrowing of the Doppler background in the fluorescence spectra. The coherence decay rate is also low for such atoms as they do not meet with the cell walls. A theoretical model based on five level optical Bloch equations is used to simulate the spectra. The Doppler convolution includes all possible orientation of atomic velocities with respect to the laser beam direction. The simulated curves reproduce the observed sharp EIT peaks and enhanced broad VSOP signals for the closed probe transition in the fluorescence and absorption spectra. The observed effect of the light intensity and temperature change on the non-linear features is reproduced by the simulation.

  3. A simple optical fibre probe for differentiation between healthy and tumorous tissue

    Science.gov (United States)

    Schartner, Erik P.; Henderson, Matthew R.; Purdey, Malcolm; Monro, Tanya M.; Gill, P. Grantley; Callen, David F.

    2016-11-01

    Incomplete removal of malignant tumours continues to be a significant issue in cancer surgery. It increases the risk of local recurrence and impaired survival, and results in the need for additional surgery with associated attendant costs and morbidity. While pathological methods exist to determine tissue type during surgery, these methods can compromise post-operative pathology, have a lag of minutes to hours before the surgeon receives the results of the tissue analysis and are restricted to excised tissue. In this work we report the development of an optical fibre probe which could find use as an aid for margin detection during surgery. A fluorophore doped polymer coating is deposited on the tip of an optical fibre, which can then be used to record the pH by monitoring the emission spectra from the embedded indicator. The pH values of unknown tissue are measured and compared to healthy tissue, allowing for discrimination between healthy and cancerous tissue. The probe developed here shows strong potential for use during surgery, as the probe design can be readily adapted to a low-cost portable configuration which could find use in the operating theatre. Use of this probe in surgery either on excised or in-vivo tissue has the potential to improve success rates for complete removal of cancers.

  4. Probing biological nanotopology via diffusion of weakly constrained plasmonic nanorods with optical coherence tomography

    OpenAIRE

    Chhetri, Raghav K.; Blackmon, Richard L.; Wu, Wei-Chen; Hill, David B.; Button, Brian; Casbas-Hernandez, Patricia; Troester, Melissa A; Tracy, Joseph B.; Oldenburg, Amy L.

    2014-01-01

    Many diseases are characterized by nanostructural changes in connective fibers and soluble proteins, which can indicate or drive disease progression. Noninvasive methods sensitive to nanotopological changes in 3D tissue models can elucidate biophysical changes associated with disease progression. Nanoparticles probe their environment via their diffusion, which is impacted by the size and connectivity of pores into which they freely diffuse. Here, we show that optical coherence tomography prov...

  5. Fabrication and performance of a single-crystal lead magnesium niobate-lead titanate cylindrical hydrophone.

    Science.gov (United States)

    Brown, Jeremy A; Dunphy, Kevin; Leadbetter, Jeff R; Adamson, Robert B A; Beslin, Olivier

    2013-08-01

    The development of a piezoelectric hydrophone based on lead magnesium niobate-lead titanate [PbMg1/3Nb2/3O3-PbTiO3 (PMN-PT)] single-crystal piezoelectric as the hydrophone substrate is reported. Although PMN-PT can possess much higher piezoelectric sensitivity than traditional lead zirconate titanate (PZT) piezoelectrics, it is highly anisotropic and therefore there is a large gain in sensitivity only when the crystal structure is oriented in a specific direction. Because of this, simply replacing the PZT substrate with a PMN-PT cylinder is not an optimal solution because the crystal orientation does not uniformly align with the circumferential axis of the hydrophone. Therefore, a composite hydrophone that maintains the optimal crystal axis around the hydrophone circumference has been developed. An 11.3 mm diameter composite hydrophone cylinder was fabricated from a single cut PMN-PT rectangular plate. Solid end caps were applied to the cylinder and the sensitivity was directly compared with a solid PZT-5A cylindrical hydrophone of equal dimensions in a hydrophone test tank. The charge sensitivity showed a 9.1 dB improvement over the PZT hydrophone and the voltage sensitivity showed a 3.5 dB improvement. This was in good agreement with the expected theoretical improvements of 10.1 and 4.5 dB, respectively.

  6. An optical backscatter probe for time resolved droplet measurements in turbomachines

    Science.gov (United States)

    Bosdas, Ilias; Mansour, Michel; Kalfas, Anestis I.; Abhari, Reza S.

    2016-01-01

    The presence of particles in the flow path of turbomachines can result in undesirable engine operation. In order to improve the efficiency of turbomachines and guarantee their safe operation, the flow mechanisms that govern the particles’ need to be studied and associated with the main aerodynamic flow field. This paper describes a newly developed optical backscatter probe for droplet diameter and speed measurements in turbomachines. The miniature probe has a tip diameter of 5 mm and is capable of resolving droplets from 40 to 110 μm in diameter that travel up to 200 m s-1. The calibration of the novel probe is performed with a droplet generator capable of producing monodispersed water droplets. In addition, the probe is calibrated for droplet speed measurements in the same calibration facility. The paper conducts a detailed uncertainty analysis and describes the post processing code. In the final part of this paper the probe is used in an axial turbine with an installed spray generator to perform droplet measurements under two different operating conditions. Measurements have shown that the part load condition results in larger droplet diameters and higher relative droplet speeds. As a consequence higher erosion rates at the rotor leading edge suction side will occur when operating at part load condition.

  7. Broadband sensitive pump-probe setup for ultrafast optical switching of photonic nanostructures and semiconductors.

    Science.gov (United States)

    Euser, Tijmen G; Harding, Philip J; Vos, Willem L

    2009-07-01

    We describe an ultrafast time resolved pump-probe spectroscopy setup aimed at studying the switching of nanophotonic structures. Both femtosecond pump and probe pulses can be independently tuned over broad frequency range between 3850 and 21,050 cm(-1). A broad pump scan range allows a large optical penetration depth, while a broad probe scan range is crucial to study strongly photonic crystals. A new data acquisition method allows for sensitive pump-probe measurements, and corrects for fluctuations in probe intensity and pump stray light. We observe a tenfold improvement of the precision of the setup compared to laser fluctuations, allowing a measurement accuracy of better than DeltaR=0.07% in a 1 s measurement time. Demonstrations of the improved technique are presented for a bulk Si wafer, a three-dimensional Si inverse opal photonic bandgap crystal, and z-scan measurements of the two-photon absorption coefficient of Si, GaAs, and the three-photon absorption coefficient of GaP in the infrared wavelength range.

  8. Underwater Acoustic Sensing with Optical Fibres

    Directory of Open Access Journals (Sweden)

    V. V. Rampal

    1982-01-01

    Full Text Available The use of optical fibres for the detection of acoustic pressure underwater has been discussed with particular reference to the recent literature on the development of fibre optic hydrophones.

  9. Measurements of linear and circular birefringence in metals by femtosecond optical pump-probe spectroscopy

    CERN Document Server

    Wilks, R

    2002-01-01

    Optically induced transient linear and circular birefringence has been studied in three different materials: ferromagnetic Ni, semiconducting GaAs and the non-magnetic metal Al. A pump-probe experiment with sub-ps resolution was set up for this purpose. The time-resolved reflectivity, rotation and ellipticity of the reflected probe beam were recorded after pumping with light of variable helicity. In the Ni sample an ultrafast demagnetisation effect was observed and the variation of the rotation and ellipticity on sub-picosecond time scales was compared. Rotation and ellipticity were found to have a similar time dependence. In GaAs, optical orientation of spin was achieved and the subsequent spin relaxation was measured for different pump powers. Fitting of the optical rotation data has revealed the power dependence of the various decay constants. In the Al sample a small signal was observed that decays on ps time scales. This was attributed to a linear birefringence effect resulting from a cubic optical nonli...

  10. All-optical optoacoustic microscopy based on probe beam deflection technique

    Directory of Open Access Journals (Sweden)

    Saher M. Maswadi

    2016-09-01

    Full Text Available Optoacoustic (OA microscopy using an all-optical system based on the probe beam deflection technique (PBDT for detection of laser-induced acoustic signals was investigated as an alternative to conventional piezoelectric transducers. PBDT provides a number of advantages for OA microscopy including (i efficient coupling of laser excitation energy to the samples being imaged through the probing laser beam, (ii undistorted coupling of acoustic waves to the detector without the need for separation of the optical and acoustic paths, (iii high sensitivity and (iv ultrawide bandwidth. Because of the unimpeded optical path in PBDT, diffraction-limited lateral resolution can be readily achieved. The sensitivity of the current PBDT sensor of 22 μV/Pa and its noise equivalent pressure (NEP of 11.4 Pa are comparable with these parameters of the optical micro-ring resonator and commercial piezoelectric ultrasonic transducers. Benefits of the present prototype OA microscope were demonstrated by successfully resolving micron-size details in histological sections of cardiac muscle.

  11. Tapered optical fibers as tools for probing magneto-optical trap characteristics

    OpenAIRE

    2009-01-01

    We present a novel technique for measuring the characteristics of a magneto-optical trap (MOT) for cold atoms by monitoring the spontaneous emission from trapped atoms coupled into the guided mode of a tapered optical nanofiber. We show that the nanofiber is highly sensitive to very small numbers of atoms close to its surface. The size and shape of the MOT, determined by translating the cold atom cloud across the tapered fiber, is in excellent agreement with measurements obtained using the co...

  12. Interferometric pump-probe characterization of the nonlocal response of optically transparent ion implanted polymers

    Science.gov (United States)

    Stefanov, Ivan L.; Hadjichristov, Georgi B.

    2012-03-01

    Optical interferometric technique is applied to characterize the nonlocal response of optically transparent ion implanted polymers. The thermal nonlinearity of the ion-modified material in the near-surface region is induced by continuous wave (cw) laser irradiation at a relatively low intensity. The interferometry approach is demonstrated for a subsurface layer of a thickness of about 100 nm formed in bulk polymethylmethacrylate (PMMA) by implantation with silicon ions at an energy of 50 keV and fluence in the range 1014-1017 cm-2. The laser-induced thermooptic effect in this layer is finely probed by interferometric imaging. The interference phase distribution in the plane of the ion implanted layer is indicative for the thermal nonlinearity of the near-surface region of ion implanted optically transparent polymeric materials.

  13. Optic probe for multiple angle image capture and optional stereo imaging

    Energy Technology Data Exchange (ETDEWEB)

    Malone, Robert M.; Kaufman, Morris I.

    2016-11-29

    A probe including a multiple lens array is disclosed to measure velocity distribution of a moving surface along many lines of sight. Laser light, directed to the moving surface is reflected back from the surface and is Doppler shifted, collected into the array, and then directed to detection equipment through optic fibers. The received light is mixed with reference laser light and using photonic Doppler velocimetry, a continuous time record of the surface movement is obtained. An array of single-mode optical fibers provides an optic signal to the multiple lens array. Numerous fibers in a fiber array project numerous rays to establish many measurement points at numerous different locations. One or more lens groups may be replaced with imaging lenses so a stereo image of the moving surface can be recorded. Imaging a portion of the surface during initial travel can determine whether the surface is breaking up.

  14. All-optical optoacoustic microscopy system based on probe beam deflection technique

    Science.gov (United States)

    Maswadi, Saher M.; Tsyboulskic, Dmitri; Roth, Caleb C.; Glickman, Randolph D.; Beier, Hope T.; Oraevsky, Alexander A.; Ibey, Bennett L.

    2016-03-01

    It is difficult to achieve sub-micron resolution in backward mode OA microscopy using conventional piezoelectric detectors, because of wavefront distortions caused by components placed in the optical path, between the sample and the objective lens, that are required to separate the acoustic wave from the optical beam. As an alternate approach, an optoacoustic microscope (OAM) was constructed using the probe beam deflection technique (PBDT) to detect laserinduced acoustic signals. The all-optical OAM detects laser-generated pressure waves using a probe beam passing through a coupling medium, such as water, filling the space between the microscope objective lens and sample. The acoustic waves generated in the sample propagate through the coupling medium, causing transient changes in the refractive index that deflect the probe beam. These deflections are measured with a high-speed, balanced photodiode position detector. The deflection amplitude is directly proportional to the magnitude of the acoustic pressure wave, and provides the data required for image reconstruction. The sensitivity of the PBDT detector expressed as noise equivalent pressure was 12 Pa, comparable to that of existing high-performance ultrasound detectors. Because of the unimpeded working distance, a high numerical aperture objective lens, i.e. NA = 1, was employed in the OAM to achieve near diffraction-limited lateral resolution of 0.5 μm at 532nm. The all-optical OAM provides several benefits over current piezoelectric detector-based systems, such as increased lateral and axial resolution, higher sensitivity, robustness, and potentially more compatibility with multimodal instruments.

  15. Fiber-Optic Imaging Probe Developed for Space Used to Detect Diabetes Through the Eye

    Science.gov (United States)

    Ansari, Rafat R.; Chenault, Michelle V.; Datiles, Manuel B., III; Sebag, J.; Suh, Kwang I.

    2000-01-01

    Approximately 16 million Americans have diabetes mellitus, which can severely impair eyesight by causing cataracts, diabetic retinopathy, and glaucoma. Cataracts are 1.6 times more common in people with diabetes than in those without diabetes, and cataract extraction is the only surgical treatment. In many cases, diabetes-related ocular pathologies go undiagnosed until visual function is compromised. This ongoing pilot project seeks to study the progression of diabetes in a unique animal model by monitoring changes in the lens with a safe, sensitive, dynamic light-scattering probe. Dynamic light scattering (DLS), has the potential to diagnose cataracts at the molecular level. Recently, a new DLS fiber-optic probe was developed at the NASA Glenn Research Center at Lewis Field for noncontact, accurate, and extremely sensitive particle-sizing measurements in fluid dispersions and suspensions (ref. 1). This compact, portable, and rugged probe is free of optical alignment, offers point-and-shoot operation for various online field applications and challenging environments, and yet is extremely flexible in regards to sample container sizes, materials, and shapes. No external vibration isolation and no index matching are required. It can measure particles as small as 1 nm and as large as few micrometers in a wide concentration range from very dilute (waterlike) dispersions to very turbid (milklike) suspensions. It is safe and fast to use, since it only requires very low laser power (10 nW to 3 mW) with very short data acquisition times (2 to 10 sec).

  16. Probing the electric field in organic double layer-system by optical second harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Eunju; Shibata, Yoshinori; Manaka, Takaaki [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Iwamoto, Mitsumasa, E-mail: iwamoto@ome.pe.titech.ac.j [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2009-11-30

    Optical electric field induced second harmonic generation (EFISHG) measurements were employed to probe the electric field in the active layer of organic field effect transistors (OFETs) and organic light emitting diodes (OLEDs). The OFETs used were double-layered with an active layer of pentacene/poly (3-hexyl thiophene) P3HT on SiO{sub 2} gate insulator with Au source and drain electrodes. It was shown that SHG from the P3HT bottom layer could be selectively probed at a wavelength of 450 nm. Similarly, by using OLEDs comprised of a double layer of Tris(8-hydroxyquinolinato) aluminium (Alq{sub 3}) and N'-di(1-naphthyl)-N,N'-diphenylbenzidine ({alpha}-NPD) with a device structure of indium-zinc oxide (IZO)/{alpha}-NPD/Alq{sub 3}/Al, it was shown that EFISHG from the Alq{sub 3} layer could be selectively probed at a wavelength of 1000 nm by reflective laser beam irradiation from IZO-side. The results show that the spectroscopic nature of materials allows us to selectively probe the electric field distribution in each layer of multi-layer in organic devices.

  17. Wearable near-infrared optical probe for continuous monitoring during breast cancer neoadjuvant chemotherapy infusions

    Science.gov (United States)

    Teng, Fei; Cormier, Timothy; Sauer-Budge, Alexis; Chaudhury, Rachita; Pera, Vivian; Istfan, Raeef; Chargin, David; Brookfield, Samuel; Ko, Naomi Yu; Roblyer, Darren M.

    2017-01-01

    We present a new continuous-wave wearable diffuse optical probe aimed at investigating the hemodynamic response of locally advanced breast cancer patients during neoadjuvant chemotherapy infusions. The system consists of a flexible printed circuit board that supports an array of six dual wavelength surface-mount LED and photodiode pairs. The probe is encased in a soft silicone housing that conforms to natural breast shape. Probe performance was evaluated using tissue-simulating phantoms and in vivo normal volunteer measurements. High SNR (71 dB), low source-detector crosstalk (-60 dB), high measurement precision (0.17%), and good thermal stability (0.22% Vrms/°C) were achieved in phantom studies. A cuff occlusion experiment was performed on the forearm of a healthy volunteer to demonstrate the ability to track rapid hemodynamic changes. Proof-of-principle normal volunteer measurements were taken to demonstrate the ability to collect continuous in vivo breast measurements. This wearable probe is a first of its kind tool to explore prognostic hemodynamic changes during chemotherapy in breast cancer patients.

  18. Ultrathin forward-imaging short multimode fiber probe for full-field optical coherence microscopy

    Science.gov (United States)

    Sato, Manabu; Saito, Daisuke; Shouji, Kou; Kurotani, Reiko; Abe, Hiroyuki; Nishidate, Izumi

    2016-12-01

    To extend the applications of optical coherence tomography (OCT) to the fields of physiology and clinical medicine, less invasive, robust, and reliable optical probes are required. Thus, we demonstrate an ultrathin forward-imaging short multimode fiber (SMMF) optical coherence microscopy (OCM) probe with a 50 μm core diameter, 125 μm total diameter, and 5.12 mm length. Imaging conditions and magnification were analyzed, and they correspond closely to the measured results. The dispersion of the SMMF was investigated, and the modal dispersion coefficient was found to be 2.3% of the material dispersion coefficient. The axial resolution was minimized at 2.15 μm using a 0.885-mm-thick dispersion compensator. The lateral resolution was evaluated to be 4.38 μm using a test pattern. The contrast of the OCM images was 5.7 times higher than that of the signal images owing to the coherence gate. The depth of focus and diameter of the field of view were measured to be 60 μm and 40-50 μm, respectively. OCM images of the dried fins of small fish (Medaka) were measured and internal structures could be recognized.

  19. A new fibre optic pulse oximeter probe for monitoring splanchnic organ arterial blood oxygen saturation.

    Science.gov (United States)

    Hickey, M; Samuels, N; Randive, N; Langford, R; Kyriacou, P A

    2012-12-01

    A new, continuous method of monitoring splanchnic organ oxygen saturation (SpO(2)) would make the early detection of inadequate tissue oxygenation feasible, reducing the risk of hypoperfusion, severe ischaemia, and, ultimately, death. In an attempt to provide such a device, a new fibre optic based reflectance pulse oximeter probe and processing system were developed followed by an in vivo evaluation of the technology on seventeen patients undergoing elective laparotomy. Photoplethysmographic (PPG) signals of good quality and high signal-to-noise ratio were obtained from the small bowel, large bowel, liver and stomach. Simultaneous peripheral PPG signals from the finger were also obtained for comparison purposes. Analysis of the amplitudes of all acquired PPG signals indicated much larger amplitudes for those signals obtained from splanchnic organs than those obtained from the finger. Estimated SpO(2) values for splanchnic organs showed good agreement with those obtained from the finger fibre optic probe and those obtained from a commercial device. These preliminary results suggest that a miniaturized 'indwelling' fibre optic sensor may be a suitable method for pre-operative and post-operative evaluation of splanchnic organ SpO(2) and their health.

  20. Optical nanofibre integrated into an optical tweezers for particle manipulation, in situ fibre probing, and optical binding studies

    CERN Document Server

    Gusachenko, Ivan; Frawley, Mary C; Chormaic, Síle Nic

    2015-01-01

    Precise control of particle positioning is desirable in many optical propulsion and sorting applications. Here, we develop an integrated platform for particle manipulation consisting of a combined optical nanofibre and optical tweezers system. Individual silica microspheres were introduced to the nanofibre at arbitrary points using the optical tweezers, thereby producing pronounced dips in the fibre transmission. We show that such consistent and reversible transmission modulations depend on both particle and fibre diameter, and can be used as a reference point for in situ nanofibre or particle size measurement. Thence, we combine scanning electron microscope (SEM) size measurements with nanofibre transmission data to provide calibration for particle-based fibre assessment. This integrated optical platform provides a method for selective evanescent field manipulation of micron-sized particles and facilitates studies of optical binding and light-particle interaction dynamics.

  1. Probing Matter-Field and Atom-Number Correlations in Optical Lattices by Global Nondestructive Addressing

    CERN Document Server

    Kozlowski, Wojciech; Mekhov, Igor B

    2014-01-01

    We show that light scattering from an ultracold gas reveals not only density correlations, but also matter-field interference at its shortest possible distance in an optical lattice, which defines key properties such as tunneling and matter-field phase gradients. This signal can be enhanced by concentrating probe light between lattice sites rather than at density maxima. As addressing between two single sites is challenging, we focus on global nondestructive scattering, allowing probing order parameters, matter-field quadratures and their squeezing. The scattering angular distribution displays peaks even if classical diffraction is forbidden and we derive generalized Bragg conditions. Light scattering distinguishes all phases in the Mott insulator - superfluid - Bose glass phase transition.

  2. Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

    Institute of Scientific and Technical Information of China (English)

    Robed Schmitt; Tilo Pfeifer; Frank Depiereux; Niels K(o)nig

    2008-01-01

    Today,micro-system technology and the development of new MEMS(Micro-Eleetro-Mechanical Systems)ate emerging rapidly.In order for this development to become a SUCCESS in the long run,measurement systems have to ensure product quality.Most often,MEMS have to be tested by means of functionality or destructive tests.One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities.We present a measurement system that could be used for these kinds of measurements.The system combines a fiber optical,miniaturized sensing probe with low-coherence intcrferometry,so that absolute distance measurements with nanometcr accuracy are possible.

  3. Single potassium niobate nano/microsized particles as local mechano-optical Brownian probes

    Science.gov (United States)

    Mor, Flavio M.; Sienkiewicz, Andrzej; Magrez, Arnaud; Forró, László; Jeney, Sylvia

    2016-03-01

    Perovskite alkaline niobates, due to their strong nonlinear optical properties, including birefringence and the capability to produce second-harmonic generation (SHG) signals, attract a lot of attention as potential candidates for applications as local nano/microsized mechano-optical probes. Here, we report on an implementation of photonic force microscopy (PFM) to explore the Brownian motion and optical trappability of monocrystalline potassium niobate (KNbO3) nano/microsized particles having sizes within the range of 50 to 750 nm. In particular, we exploit the anisotropic translational diffusive regime of the Brownian motion to quantify thermal fluctuations and optical forces of singly-trapped KNbO3 particles within the optical trapping volume of a PFM microscope. We also show that, under near-infrared (NIR) excitation of the highly focused laser beam of the PFM microscope, a single optically-trapped KNbO3 particle reveals a strong SHG signal manifested by a narrow peak (λem = 532 nm) at half the excitation wavelength (λex = 1064 nm). Moreover, we demonstrate that the thus induced SHG emission can be used as a local light source that is capable of optically exciting molecules of an organic dye, Rose Bengal (RB), which adhere to the particle surface, through the mechanism of luminescence energy transfer (LET).Perovskite alkaline niobates, due to their strong nonlinear optical properties, including birefringence and the capability to produce second-harmonic generation (SHG) signals, attract a lot of attention as potential candidates for applications as local nano/microsized mechano-optical probes. Here, we report on an implementation of photonic force microscopy (PFM) to explore the Brownian motion and optical trappability of monocrystalline potassium niobate (KNbO3) nano/microsized particles having sizes within the range of 50 to 750 nm. In particular, we exploit the anisotropic translational diffusive regime of the Brownian motion to quantify thermal

  4. Molecular Imaging Probes for Positron Emission Tomography and Optical Imaging of Sentinel Lymph Node and Tumor

    Science.gov (United States)

    Qin, Zhengtao

    Molecular imaging is visualizations and measurements of in vivo biological processes at the molecular or cellular level using specific imaging probes. As an emerging technology, biocompatible macromolecular or nanoparticle based targeted imaging probes have gained increasing popularities. Those complexes consist of a carrier, an imaging reporter, and a targeting ligand. The active targeting ability dramatically increases the specificity. And the multivalency effect may further reduce the dose while providing a decent signal. In this thesis, sentinel lymph node (SLN) mapping and cancer imaging are two research topics. The focus is to develop molecular imaging probes with high specificity and sensitivity, for Positron Emission Tomography (PET) and optical imaging. The objective of this thesis is to explore dextran radiopharmaceuticals and porous silicon nanoparticles based molecular imaging agents. Dextran polymers are excellent carriers to deliver imaging reporters or therapeutic agents due to its well established safety profile and oligosaccharide conjugation chemistry. There is also a wide selection of dextran polymers with different lengths. On the other hand, Silicon nanoparticles represent another class of biodegradable materials for imaging and drug delivery. The success in fluorescence lifetime imaging and enhancements of the immune activation potency was briefly discussed. Chapter 1 begins with an overview on current molecular imaging techniques and imaging probes. Chapter 2 presents a near-IR dye conjugated probe, IRDye 800CW-tilmanocept. Fluorophore density was optimized to generate the maximum brightness. It was labeled with 68Ga and 99mTc and in vivo SLN mapping was successfully performed in different animals, such as mice, rabbits, dogs and pigs. With 99mTc labeled IRDye 800CW-tilmanocept, chapter 3 introduces a two-day imaging protocol with a hand-held imager. Chapter 4 proposed a method to dual radiolabel the IRDye 800CW-tilmanocept with both 68Ga and

  5. Probing the micro-rheological properties of aerosol particles using optical tweezers.

    Science.gov (United States)

    Power, Rory M; Reid, Jonathan P

    2014-07-01

    The use of optical trapping techniques to manipulate probe particles for performing micro-rheological measurements on a surrounding fluid is well-established. Here, we review recent advances made in the use of optical trapping to probe the rheological properties of trapped particles themselves. In particular, we review observations of the continuous transition from liquid to solid-like viscosity of sub-picolitre supersaturated solution aerosol droplets using optical trapping techniques. Direct measurements of the viscosity of the particle bulk are derived from the damped oscillations in shape following coalescence of two particles, a consequence of the interplay between viscous and surface forces and the capillary driven relaxation of the approximately spheroidal composite particle. Holographic optical tweezers provide a facile method for the manipulation of arrays of particles allowing coalescence to be controllably induced between two micron-sized aerosol particles. The optical forces, while sufficiently strong to confine the composite particle, are several orders of magnitude weaker than the capillary forces driving relaxation. Light, elastically back-scattered by the particle, is recorded with sub-100 ns resolution allowing measurements of fast relaxation (low viscosity) dynamics, while the brightfield image can be used to monitor the shape relaxation extending to times in excess of 1000 s. For the slowest relaxation dynamics studied (particles with the highest viscosity) the presence and line shape of whispering gallery modes in the cavity enhanced Raman spectrum can be used to infer the relaxation time while serving the dual purpose of allowing the droplet size and refractive index to be measured with accuracies of ±0.025% and ±0.1%, respectively. The time constant for the damped relaxation can be used to infer the bulk viscosity, spanning from the dilute solution limit to a value approaching that of a glass, typically considered to be >10(12)

  6. Sub-wavelength imaging by depolarization in a reflection near-field optical microscope using an uncoated fiber probe

    DEFF Research Database (Denmark)

    Madsen, Steen; Bozhevolnyi, Sergey I.; Hvam, Jørn Märcher

    1998-01-01

    We present a reflection scanning near-field optical microscope utilizing counter-directional light propagation in an uncoated fiber probe, cross-polarized detection and shear-force feedback. Topographical and near-field optical imaging with a scanning speed of up to 10 mu m/s and a lateral...

  7. Single shot, temporally and spatially resolved measurements of fast electron dynamics using a chirped optical probe

    Science.gov (United States)

    Green, J. S.; Murphy, C. D.; Booth, N.; Dance, R. J.; Gray, R. J.; MacLellan, D. A.; McKenna, P.; Rusby, D.; Wilson, L.

    2014-03-01

    A new approach to rear surface optical probing is presented that permits multiple, time-resolved 2D measurements to be made during a single, ultra-intense ( > 1018 W cm-2) laser-plasma interaction. The diagnostic is capable of resolving rapid changes in target reflectivity which can be used to infer valuable information on fast electron transport and plasma formation at the target rear surface. Initial results from the Astra-Gemini laser are presented, with rapid radial sheath expansion together with detailed filamentary features being observed to evolve during single shots.

  8. Optical method for distance and displacement measurements of the probe-sample separation in a scanning near-field optical microscope

    Energy Technology Data Exchange (ETDEWEB)

    Santamaria, L.; Siller, H. R. [Tecnológico de Monterrey, Eugenio Garza Sada 2501 Sur, Monterrey, N.L., 64849 (Mexico); Garcia-Ortiz, C. E., E-mail: cegarcia@cicese.mx [CONACYT Research Fellow – CICESE, Unidad Monterrey, Alianza Centro 504, Apodaca, NL, 66629 (Mexico); Cortes, R.; Coello, V. [CICESE, Unidad Monterrey, PIIT, Alianza Centro 504, Apodaca, NL, 66629 (Mexico)

    2016-04-15

    In this work, we present an alternative optical method to determine the probe-sample separation distance in a scanning near-field optical microscope. The experimental method is based in a Lloyd’s mirror interferometer and offers a measurement precision deviation of ∼100 nm using digital image processing and numerical analysis. The technique can also be strategically combined with the characterization of piezoelectric actuators and stability evaluation of the optical system. It also opens the possibility for the development of an automatic approximation control system valid for probe-sample distances from 5 to 500 μm.

  9. Tapered optical fibers as tools for probing magneto-optical trap characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Morrissey, Michael J.; Deasy, Kieran [Department of Applied Physics and Instrumentation, Cork Institute of Technology, Cork (Ireland); Photonics Centre, Tyndall National Institute, University College Cork, Prospect Row, Cork (Ireland); Wu Yuqiang; Nic Chormaic, Sile [Photonics Centre, Tyndall National Institute, University College Cork, Prospect Row, Cork (Ireland); Department of Physics, University College Cork, Cork (Ireland); Chakrabarti, Shrabana [Photonics Centre, Tyndall National Institute, University College Cork, Prospect Row, Cork (Ireland)

    2009-05-15

    We present a novel technique for measuring the characteristics of a magneto-optical trap (MOT) for cold atoms by monitoring the spontaneous emission from trapped atoms coupled into the guided mode of a tapered optical nanofiber. We show that the nanofiber is highly sensitive to very small numbers of atoms close to its surface. The size and shape of the MOT, determined by translating the cold atom cloud across the tapered fiber, is in excellent agreement with measurements obtained using the conventional method of fluorescence imaging using a charge coupled device camera. The coupling of atomic fluorescence into the tapered fiber also allows us to monitor the loading and lifetime of the trap. The results are compared to those achieved by focusing the MOT fluorescence onto a photodiode and it was seen that the tapered fiber gives slightly longer loading and lifetime measurements due to the sensitivity of the fiber, even when very few atoms are present.

  10. Tapered optical fibers as tools for probing magneto-optical trap characteristics

    Science.gov (United States)

    Morrissey, Michael J.; Deasy, Kieran; Wu, Yuqiang; Chakrabarti, Shrabana; Nic Chormaic, Síle

    2009-05-01

    We present a novel technique for measuring the characteristics of a magneto-optical trap (MOT) for cold atoms by monitoring the spontaneous emission from trapped atoms coupled into the guided mode of a tapered optical nanofiber. We show that the nanofiber is highly sensitive to very small numbers of atoms close to its surface. The size and shape of the MOT, determined by translating the cold atom cloud across the tapered fiber, is in excellent agreement with measurements obtained using the conventional method of fluorescence imaging using a charge coupled device camera. The coupling of atomic fluorescence into the tapered fiber also allows us to monitor the loading and lifetime of the trap. The results are compared to those achieved by focusing the MOT fluorescence onto a photodiode and it was seen that the tapered fiber gives slightly longer loading and lifetime measurements due to the sensitivity of the fiber, even when very few atoms are present.

  11. Intrinsic carrier multiplication efficiency in bulk Si crystals evaluated by optical-pump/terahertz-probe spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yamashita, G.; Nagai, M., E-mail: mnagai@mp.es.osaka-u.ac.jp, E-mail: ashida@mp.es.osaka-u.ac.jp; Ashida, M., E-mail: mnagai@mp.es.osaka-u.ac.jp, E-mail: ashida@mp.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, Osaka 560-8531 (Japan); Matsubara, E. [Graduate School of Engineering Science, Osaka University, Osaka 560-8531 (Japan); Department of Physics, Osaka Dental University, Hirakata, Osaka 573-1121 (Japan); Kanemitsu, Y. [Institute for Chemical Research, Kyoto University, Kyoto 611-0011 (Japan)

    2014-12-08

    We estimated the carrier multiplication efficiency in the most common solar-cell material, Si, by using optical-pump/terahertz-probe spectroscopy. Through close analysis of time-resolved data, we extracted the exact number of photoexcited carriers from the sheet carrier density 10 ps after photoexcitation, excluding the influences of spatial diffusion and surface recombination in the time domain. For incident photon energies greater than 4.0 eV, we observed enhanced internal quantum efficiency due to carrier multiplication. The evaluated value of internal quantum efficiency agrees well with the results of photocurrent measurements. This optical method allows us to estimate the carrier multiplication and surface recombination of carriers quantitatively, which are crucial for the design of the solar cells.

  12. Fiber-optic probe for noninvasive real-time determination of tissue optical properties at multiple wavelengths.

    Science.gov (United States)

    Dam, J S; Pedersen, C B; Dalgaard, T; Fabricius, P E; Aruna, P; Andersson-Engels, S

    2001-03-01

    We present a compact, fast, and versatile fiber-optic probe system for real-time determination of tissue optical properties from spatially resolved continuous-wave diffuse reflectance measurements. The system collects one set of reflectance data from six source-detector distances at four arbitrary wavelengths with a maximum overall sampling rate of 100 Hz. Multivariate calibration techniques based on two-dimensional polynomial fitting are employed to extract and display the absorption and reduced scattering coefficients in real-time mode. The four wavelengths of the current configuration are 660, 785, 805, and 974 nm, respectively. Cross-validation tests on a 6 x 7 calibration matrix of Intralipid-dye phantoms showed that the mean prediction error at, e.g., 785 nm was 2.8% for the absorption coefficient and 1.3% for the reduced scattering coefficient. The errors are relative to the range of the optical properties of the phantoms at 785 nm, which were 0-0.3/cm for the absorption coefficient and 6-16/cm for the reduced scattering coefficient. Finally, we also present and discuss results from preliminary skin tissue measurements.

  13. Validity Using Pump-Probe Pulses to Determine the Optical Response of Niobate Crystals

    Science.gov (United States)

    Liu, Huimin; Jia, Weiyi

    1997-01-01

    A variety of niobate crystals have found their places in nonlinear optical applications as well as in laser devices. In recent years much attention has been paid to study the ultrafast optical response in a variety of photorefractive crystals such as KTa(1-x)Nb(x)O3 and KNbO3 crystals, glasses, semiconductors and polymers for applications in optical switching, information processing, optical computing, and all-optical device systems. Third-order optical nonlinearity is the most important property for realization of all-optical switching. Therefore experiments have been performed on the third order susceptibility using a variety of techniques such as the third-order harmonic generation, EFISH and degenerate four-wave mixing(DFWM). The latter has been conducted with a variety of pump wavelengths and with nanosecond, picosecond and femtosecond pulses. Niobate crystals, such as potassium niobate KNbO3, potassium tantalate niobate KTN family (KTa(1-x)Nb(x)O3), strontium barium niobate SBN (Sr(x)Ba(1-x)Nb2O6) and potassium-sodium niobate SBN (KNSBN) are attractive due to their photorefractive properties for application in optical storage and processing. The pulsed probe experiments performed on theses materials have suggested two types of time responses. These responses have been associated with an coherent response due to Chi(sup 3), and a long lived component due to excited state population. Recent study of DFWM on KNbO3 and KTN family reveals that the long lived component of those crystals depends on the crystal orientation. A slowly decaying signal is observable when the grating vector K(sub g) is not perpendicular to the C-axis of those photorefractive crystals', otherwise the optical response signal would be only a narrow coherent peak with FWHM equal to the cross-correlation width of the write beam pulses. Based on this understanding, we study the photodynamical process of a variety of niobate crystals using DFWM in a Kg perpindicular to C geometry with a ps

  14. Optical dating in a new light: A direct, non-destructive probe of trapped electrons.

    Science.gov (United States)

    Prasad, Amit Kumar; Poolton, Nigel R J; Kook, Myungho; Jain, Mayank

    2017-09-26

    Optical dating has revolutionized our understanding of Global climate change, Earth surface processes, and human evolution and dispersal over the last ~500 ka. Optical dating is based on an anti-Stokes photon emission generated by electron-hole recombination within quartz or feldspar; it relies, by default, on destructive read-out of the stored chronometric information. We present here a fundamentally new method of optical read-out of the trapped electron population in feldspar. The new signal termed as Infra-Red Photo-Luminescence (IRPL) is a Stokes emission (~1.30 eV) derived from NIR excitation (~1.40 eV) on samples previously exposed to ionizing radiation. Low temperature (7-295 K) spectroscopic and time-resolved investigations suggest that IRPL is generated from excited-to-ground state relaxation within the principal (dosimetry) trap. Since IRPL can be induced even in traps remote from recombination centers, it is likely to contain a stable (non-fading), steady-state component. While IRPL is a powerful tool to understand details of the electron-trapping center, it provides a novel, alternative approach to trapped-charge dating based on direct, non-destructive probing of chronometric information. The possibility of repeated readout of IRPL from individual traps will open opportunities for dating at sub-micron spatial resolution, thus, marking a step change in the optical dating technology.

  15. Photoconversion of purified fluorescent proteins and dual-probe optical highlighting in live cells.

    Science.gov (United States)

    Kremers, Gert-Jan; Piston, David

    2010-06-26

    Photoconvertible fluorescent proteins (pc-FPs) are a class of fluorescent proteins with "optical highlighter" capability, meaning that the color of fluorescence can be changed by exposure to light of a specific wavelength. Optical highlighting allows noninvasive marking of a subpopulation of fluorescent molecules, and is therefore ideal for tracking single cells or organelles. Critical parameters for efficient photoconversion are the intensity and the exposure time of the photoconversion light. If the intensity is too low, photoconversion will be slow or not occur at all. On the other hand, too much intensity or too long exposure can photobleach the protein and thereby reduce the efficiency of photoconversion. This protocol describes a general approach how to set up a confocal laser scanning microscope for pc-FP photoconversion applications. First, we describe a procedure for preparing purified protein droplet samples. This sample format is very convenient for studying the photophysical behavior of fluorescent proteins under the microscope. Second, we will use the protein droplet sample to show how to configure the microscope for photoconversion. And finally, we will show how to perform optical highlighting in live cells, including dual-probe optical highlighting with mOrange2 and Dronpa.

  16. Development of a cylindrical diffusing optical fiber probe for pancreatic cancer therapy

    Science.gov (United States)

    Lee, Sangyeob; Park, Gaye; Park, Jihoon; Yu, Sungkon; Ha, Myungjin; Jang, Seulki; Ouh, Chihwan; Jung, Changhyun; Jung, Byungjo

    2017-02-01

    Although the patients with cancer on pancreas or pancreaticobiliary duct have been increased, it is very difficult to detect and to treat the pancreatic cancer because of its low accessibility and obtuseness. The pancreatic cancer has been diagnosed using ultrasonography, blood test, CT, endoscopic retrograde cholangiopancreatography (ERCP), endoscopic ultrasonography (EUS) and etc. Normally, light can be delivered to the target by optical fibers through the ERCP or EUS. Diffusing optical fibers have been developed with various methods. However, many of them have mechanical and biological problems in the use of small-bend-radius apparatus or in tissue area. This study developed a therapeutic cylindrical diffusing optical fiber probe (CDOFP) for ERCP and EUS which has moderate flexibility and solidity to treat the cancer on pancreaticobiliary duct or pancreas. The CDOFP consists of a biocompatible Teflon tube and multimode glass fiber which has diffusing area processed with laser and high refractive index resin. The CDOFP was characterized to investigate the clinical feasibility and other applications of light therapy using diffusing optical fiber. The results presented that the CDOFP may be used in clinic by combining with endoscopic method, such as ERCP or EUS, to treat cancer on pancreas and pancreaticobiliary duct.

  17. Targeted illumination and tracking using optical fiber probe for optogenetics application

    Science.gov (United States)

    Shinde, Anant; Perinchery, Sandeep M.; Matham, Murukeshan V.

    2016-03-01

    There was a renewed interest, during the recent years, in the imaging and tracking of targeted cells or organelles for a variety of biomedical and lab-on a chip applications that include particles movement. However, nonspecific illumination during tracking can have adverse effects such as heating, reduced image contrast and photo bleaching. In fact, current available tracking and imaging systems are unable to selectively illuminate the particle being tracked. To fill this void, we have developed a fiber optics based probe system incorporating a spatial light modulator (SLM) and an imaging fiber bundle for selective illumination on the targeted particle. A GRIN lens is attached at the distal endface of the image fiber bundle for optimised illumination and collection. A tracking algorithm is developed in order to enable controlled illumination through SLM to target the illumination point or location in accordance with the particle movement and size variation. Further with this probe, particles can be illuminated with light pulses of controllable duty cycle and frequency. The proposed methodology and developed probe have good significance and expected to find potential applications areas such as optogenetics, cell signalling studies, and lab-on a chip systems.

  18. Determination of inorganic elements in animal feeds by NIRS technology and a fibre-optic probe.

    Science.gov (United States)

    González-Martín, Inmaculada; Alvarez-García, Noelia; González-Pérez, Claudio; Villaescusa-García, Virginia

    2006-05-15

    In the present work we study the use of near infra-red spectroscopy (NIRS) technology together with a remote reflectance fibre-optic probe for the analysis of the mineral composition of animal feeds. The method allows immediate control of the feeds without prior sample treatment or destruction through direct application of the fibre-optic probe on the sample. The regression method employed was modified partial least squares (MPLS). The calibration results obtained using forty samples of animal feeds allowed the determination of Fe, Mn, Ca, Na, K, P, Zn and Cu, with a standard error of prediction (SEP(C)) and a correlation coefficient (RSQ) of 0.129 and 0.859 for Fe; 0.175 and 0.816 for Mn; 5.470 and 0.927 for Ca; 2.717 and 0.862 for Na; 4.397 and 0.891 for K; 2.226 and 0.881 for P; 0.153 and 0.764 for Zn, and 0.095 and 0.918 for Cu, respectively. The robustness of the method was checked by applying it to 10 animal feeds samples of unknown mineral composition in the external validation.

  19. Rat brain imaging using full field optical coherence microscopy with short multimode fiber probe

    Science.gov (United States)

    Sato, Manabu; Saito, Daisuke; Kurotani, Reiko; Abe, Hiroyuki; Kawauchi, Satoko; Sato, Shunichi; Nishidate, Izumi

    2017-02-01

    We demonstrated FF OCM(full field optical coherence microscopy) using an ultrathin forward-imaging SMMF (short multimode fiber) probe of 50 μm core diameter, 125 μm diameter, and 7.4 mm length, which is a typical graded-index multimode fiber for optical communications. The axial resolution was measured to be 2.20 μm, which is close to the calculated axial resolution of 2.06 μm. The lateral resolution was evaluated to be 4.38 μm using a test pattern. Assuming that the FWHM of the contrast is the DOF (depth of focus), the DOF of the signal is obtained at 36 μm and that of the OCM is 66 μm. The contrast of the OCT images was 6.1 times higher than that of the signal images due to the coherence gate. After an euthanasia the rat brain was resected and cut at 2.6mm tail from Bregma. Contacting SMMF to the primary somatosensory cortex and the agranular insular cortex of ex vivo brain, OCM images of the brain were measured 100 times with 2μm step. 3D OCM images of the brain were measured, and internal structure information was obtained. The feasibility of an SMMF as an ultrathin forward-imaging probe in full-field OCM has been demonstrated.

  20. Optical pump wavelength dependence in visible-pump visible-probe spectroscopy of noble metals

    Science.gov (United States)

    Sahota, Derek G.; Lobo, Calvin; Duch, Konrad; Dodge, J. Steven

    2012-10-01

    We have developed a femtosecond visible-pump visible-probe reflectometer with individually tunable pump and probe photon energies. The spectrometer has been used to study optically thick films of the noble metals Au and Cu over a wide variety of pump fluences and photon energies. Through comparison between experimental measurements and two-temperature model (TTM) simulations, we estimate an electron-phonon coupling constant, g, of 2.37 ±0.11 x10^16 Wm-3K-1 for Au and 1.19 ±0.13 x10^17 Wm-3K-1 for Cu, consistent with previous studies. The variation of the optical pump parameters allows a more accurate determination of the electron-phonon coupling constant. The relaxation rate, τ, of the thermally excited electrons is shown to be strongly dependent on the peak electron temperature of the excited sample, and only weakly dependent on the pump photon energy. The static dielectric constant is found to significantly underestimate the dependence of the differential reflectivity on the pump photon energy.

  1. Probing the size dependence on the optical modes of anatase nanoplatelets using STEM-EELS

    Science.gov (United States)

    Liberti, Emanuela; Menzel, Robert; Shaffer, Milo S. P.; McComb, David W.

    2016-05-01

    Anatase titania nanoplatelets with predominantly exposed {001} facets have been reported to have enhanced catalytic properties in comparison with bulk anatase. To understand their unusual behaviour, it is essential to fully characterize their electronic and optical properties at the nanometer scale. One way of assessing these fundamental properties is to study the dielectric function. Valence electron energy-loss spectroscopy (EELS) performed using a scanning transmission electron microscope (STEM) is the only analytical method that can probe the complex dielectric function with both high energy (platelets less than 10 nm thick, the frequency of these optical modes varies according to their thickness. This unique optical behaviour prompts the enhancement of light absorption in the ultraviolet regime. Finally, the effect of finite size on the dielectric signal is gradually lost by stacking consistently two or more platelets in a specific crystal orientation, and eventually suppressed for large stacks of platelets.Anatase titania nanoplatelets with predominantly exposed {001} facets have been reported to have enhanced catalytic properties in comparison with bulk anatase. To understand their unusual behaviour, it is essential to fully characterize their electronic and optical properties at the nanometer scale. One way of assessing these fundamental properties is to study the dielectric function. Valence electron energy-loss spectroscopy (EELS) performed using a scanning transmission electron microscope (STEM) is the only analytical method that can probe the complex dielectric function with both high energy (platelets less than 10 nm thick, the frequency of these optical modes varies according to their thickness. This unique optical behaviour prompts the enhancement of light absorption in the ultraviolet regime. Finally, the effect of finite size on the dielectric signal is gradually lost by stacking consistently two or more platelets in a specific crystal orientation

  2. Articulated dual modality photoacoustic and optical coherence tomography probe for preclinical and clinical imaging (Conference Presentation)

    Science.gov (United States)

    Liu, Mengyang; Zabihian, Behrooz; Weingast, Jessika; Hermann, Boris; Chen, Zhe; Zhang, Edward Z.; Beard, Paul C.; Pehamberger, Hubert; Drexler, Wolfgang

    2016-03-01

    The combination of photoacoustic tomography (PAT) with optical coherence tomography (OCT) has seen steady progress over the past few years. With the benchtop and semi-benchtop configurations, preclinical and clinical results have been demonstrated, paving the way for wider applications using dual modality PAT/OCT systems. However, as for the most updated semi-benchtop PAT/OCT system which employs a Fabry-Perot polymer film sensor, it is restricted to only human palm imaging due to the limited flexibility of the probe. The passband limit of the polymer film sensor further restricts the OCT source selection and reduces the sensitivity of the combined OCT system. To tackle these issues, we developed an articulated PAT/OCT probe for both preclinical and clinical applications. In the probe design, the sample arm of OCT sub-system and the interrogation part of the PAT sub-system are integrated into one compact unit. The polymer film sensor has a quick release function so that before each OCT scan, the sensor can be taken off to avoid the sensitivity drop and artefacts in OCT. The holding mechanism of the sensor is also more compact compared to previous designs, permitting access to uneven surfaces of the subjects. With the help of the articulated probe and a patient chair, we are able to perform co-registered imaging on human subjects on both upper and lower extremities while they are at rest positions. An increase in performance characteristics is also achieved. Patients with skin diseases are currently being recruited to test its clinical feasibility.

  3. Thermo-Optical Tuning of Whispering Gallery Modes in Er:Yb Doped Glass Microspheres to Arbitrary Probe Wavelengths

    CERN Document Server

    Watkins, Amy; Chormaic, Síle Nic

    2012-01-01

    We present experimental results on an all-optical, thermally-assisted technique for broad range tuning of microsphere cavity resonance modes to arbitrary probe wavelengths. An Er:Yb co-doped phosphate glass (Schott IOG-2) microsphere is pumped at 978 nm via the supporting stem and the heat generated by absorption of the pump light expands the cavity and changes the refractive index. This is a robust tuning method that decouples the pump from the probe and allows fine tuning of the microsphere's whispering gallery modes. Pump/probe experiments were performed to demonstrate thermo-optical tuning to specific probe wavelengths, including the 5S1/2 F = 3 to 5P3/2 F' = 4 laser cooling transition of 85Rb. This is of particular interest for cavity QED-type experiments, while the broad tuning range achievable is useful for integrated photonic devices, including sensors and modulators.

  4. Thermo-Optical Tuning of Whispering Gallery Modes in Erbium:Ytterbium Doped Glass Microspheres to Arbitrary Probe Wavelengths

    Science.gov (United States)

    Watkins, Amy; Ward, Jonathan; Chormaic, Síle Nic

    2012-05-01

    We present experimental results on an all-optical, thermally-assisted technique for broad range tuning of microsphere cavity resonance modes to arbitrary probe wavelengths. An erbium:ytterbium co-doped phosphate glass (Schott IOG-2) microsphere is pumped at 978 nm via the supporting stem and the heat generated by absorption of the pump light expands the cavity and changes the refractive index. This is a robust tuning method that decouples the pump from the probe and allows fine tuning of the microsphere's whispering gallery modes. Pump/probe experiments were performed to demonstrate thermo-optical tuning to specific probe wavelengths, including the 5S1/2 F= 3 to 5P3/2 F'= 4 laser cooling transition of rubidium-85. This is of particular interest for cavity quantum electrodynamics (QED)-type experiments, while the broad tuning range achievable is useful for integrated photonic devices, including sensors and modulators.

  5. Novel Strategy for Preparing Dual-Modality Optical/PET Imaging Probes via Photo-Click Chemistry.

    Science.gov (United States)

    Sun, Lingyi; Ding, Jiule; Xing, Wei; Gai, Yongkang; Sheng, Jing; Zeng, Dexing

    2016-05-18

    Preparation of small molecule based dual-modality probes remains a challenging task due to the complicated synthetic procedure. In this study, a novel concise and generic strategy for preparing dual-modality optical/PET imaging probes via photo-click chemistry was developed, in which the diazole photo-click linker functioned not only as a bridge between the targeting-ligand and the PET imaging moiety, but also as the fluorophore for optical imaging. A dual-modality AE105 peptidic probe was successfully generated via this strategy and subsequently applied in the fluorescent staining of U87MG cells and the (68)Ga based PET imaging of mice bearing U87MG xenograft. In addition, dual-modality monoclonal antibody cetuximab has also been generated via this strategy and labeled with (64)Cu for PET imaging studies, broadening the application of this strategy to include the preparation of macromolecule based imaging probes.

  6. Optical response of a quantum dot-metal nanoparticle hybrid interacting with a weak probe field.

    Science.gov (United States)

    Kosionis, Spyridon G; Terzis, Andreas F; Sadeghi, Seyed M; Paspalakis, Emmanuel

    2013-01-30

    We study optical effects in a hybrid system composed of a semiconductor quantum dot and a spherical metal nanoparticle that interacts with a weak probe electromagnetic field. We use modified nonlinear density matrix equations for the description of the optical properties of the system and obtain a closed-form expression for the linear susceptibilities of the quantum dot, the metal nanoparticle, and the total system. We then investigate the dependence of the susceptibility on the interparticle distance as well as on the material parameters of the hybrid system. We find that the susceptibility of the quantum dot exhibits optical transparency for specific frequencies. In addition, we show that there is a range of frequencies of the applied field for which the susceptibility of the semiconductor quantum dot leads to gain. This suggests that in such a hybrid system quantum coherence can reverse the course of energy transfer, allowing flow of energy from the metallic nanoparticle to the quantum dot. We also explore the susceptibility of the metal nanoparticle and show that it is strongly influenced by the presence of the quantum dot.

  7. Evaluating a hybrid three-dimensional metrology system: merging data from optical and touch probe devices

    Science.gov (United States)

    Gerde, Janice R.; Christens-Barry, William A.

    2011-08-01

    In a project to meet requirements for CBP Laboratory analysis of footwear under the Harmonized Tariff Schedule of the United States (HTSUS), a hybrid metrology system comprising both optical and touch probe devices has been assembled. A unique requirement must be met: To identify the interface-typically obscured in samples of concern-of the "external surface area upper" (ESAU) and the sole without physically destroying the sample. The sample outer surface is determined by discrete point cloud coordinates obtained using laser scanner optical measurements. Measurements from the optically inaccessible insole region are obtained using a coordinate measuring machine (CMM). That surface similarly is defined by point cloud data. Mathematically, the individual CMM and scanner data sets are transformed into a single, common reference frame. Custom software then fits a polynomial surface to the insole data and extends it to intersect the mesh fitted to the outer surface point cloud. This line of intersection defines the required ESAU boundary, thus permitting further fractional area calculations to determine the percentage of materials present. With a draft method in place, and first-level method validation underway, we examine the transformation of the two dissimilar data sets into the single, common reference frame. We also will consider the six previously-identified potential error factors versus the method process. This paper reports our on-going work and discusses our findings to date.

  8. A novel optical probe for pH sensing in gastro-esophageal apparatus

    Science.gov (United States)

    Baldini, F.; Ghini, G.; Giannetti, A.; Senesi, F.; Trono, C.

    2011-03-01

    Monitoring gastric pH for long periods, usually 24 h, may be essential in analyzing the physiological pattern of acidity, in obtaining information on changes in activity during peptic ulcer disease, and in assessing the effect of antisecretory drugs. Gastro-esophageal reflux, which causes a pH decrease in the esophagus content from pH 7 even down to pH 2, can determine esophagitis with possible strictures and Barrett's esophagus. One of the difficulties of the optical measurement of pH in the gastro-esophageal apparatus lies in the required extended working range from 1 to 8 pH units. The present paper deals with a novel optical pH sensor, using methyl red as optical pH indicator. Contrary to all acidbase indicators characterized by working ranges limited to 2-3 pH units, methyl red, after its covalent immobilization on controlled pore glass (CPG), is characterized by a wide working range which fits with the clinical requirements. The novel probe design here described is suitable for gastro-esophageal applications and allows the optimization of the performances of the CPG with the immobilised indicator. This leads to a very simple configuration characterized by a very fast response time.

  9. Development of micro-optics for high-resolution IL spectroscopy with a proton microbeam probe

    Energy Technology Data Exchange (ETDEWEB)

    Kada, Wataru, E-mail: kada.wataru@gunma-u.ac.jp [Faculty of Science and Technology, Gunma University, 1-5-1 Tenjin-machi, Kiryu, Gunma 376-8515 (Japan); Satoh, Takahiro; Yokoyama, Akihito; Koka, Masashi; Kamiya, Tomihiro [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan)

    2014-01-01

    Confocal optics for ion luminescence (IL) was developed for the precise analysis of the chemical composition of microscopic targets with an external proton microbeam probe. Anti-reflection-coated confocal micro-lens optics with an effective focus area of approximately 800 × 800 μm was installed on the microbeam line of a single-ended accelerator. Chromatic aberrations of the confocal optics were examined at wavelengths of 300–900 nm. An electrically-cooled back-thinned charge coupled device spectrometer with a wavelength resolution of 0.5 nm was used for the microscopic spectroscopy and IL imaging of microscopic mineral targets. Simultaneous microscopic IL and micro-PIXE analysis were performed using an external 3 MeV H{sup +} microbeam with a current of less than 100 pA. A spectral resolution of 3 nm was achieved for a single IL peak which corresponded to Cr{sup 3+} impurities in a single-crystal of aluminum oxide. The use of IL spectroscopy and imaging for aerosol targets revealed microscopic distributions of the chemical and elemental composition in the atmosphere.

  10. Miniature endoscopic optical coherence tomography probe employing a two-axis microelectromechanical scanning mirror with through-silicon vias.

    Science.gov (United States)

    Liu, Lin; Wu, Lei; Sun, Jingjing; Lin, Elaine; Xie, Huikai

    2011-02-01

    We present the design and experimental results of a new MEMS-based endoscopic optical coherence tomography (OCT) probe. The uniqueness of this miniature OCT imaging probe is a two-axis MEMS mirror with through-silicon vias (TSVs) for interconnecting. The TSV interconnection enables ultracompact probe design, successfully reducing the probe size to only 2.6 mm in diameter. The MEMS mirror is actuated by an electrothermal actuator that is capable of scanning ± 16° at only 3.6 V DC. Two-dimensional and three-dimensional OCT images of microspheres embedded in PDMS and acute rat brain tissue have been obtained with this miniature probe in a time-domain OCT system.

  11. Optical design and imaging performance testing of a 9.6-mm diameter femtosecond laser microsurgery probe.

    Science.gov (United States)

    Hoy, Christopher L; Ferhanoğlu, Onur; Yildirim, Murat; Piyawattanametha, Wibool; Ra, Hyejun; Solgaard, Olav; Ben-Yakar, Adela

    2011-05-23

    We present the optical design of a 9.6-mm diameter fiber-coupled probe for combined femtosecond laser microsurgery and nonlinear optical imaging. Towards enabling clinical use, we successfully reduced the dimensions of our earlier 18-mm microsurgery probe by half, while improving optical performance. We use analytical and computational models to optimize the miniaturized lens system for off-axis scanning aberrations. The optimization reveals that the optical system can be aberration-corrected using simple aspheric relay lenses to achieve diffraction-limited imaging resolution over a large field of view. Before moving forward with custom lenses, we have constructed the 9.6-mm probe using off-the-shelf spherical relay lenses and a 0.55 NA aspheric objective lens. In addition to reducing the diameter by nearly 50% and the total volume by 5 times, we also demonstrate improved lateral and axial resolutions of 1.27 µm and 13.5 µm, respectively, compared to 1.64 µm and 16.4 µm in our previous work. Using this probe, we can successfully image various tissue samples, such as rat tail tendon that required 2-3 × lower laser power than the current state-of-the-art. With further development, image-guided, femtosecond laser microsurgical probes such as this one can enable physicians to achieve the highest level of surgical precision anywhere inside the body.

  12. Optical sectioning using a fiber probe with an angled illumination-collection geometry: evaluation in engineered tissue phantoms

    Science.gov (United States)

    Nieman, Linda; Myakov, Alexey; Aaron, Jesse; Sokolov, Konstantin

    2004-02-01

    We present a fiber optic probe that combines polarized illumination and detection with an angled distal probe geometry to detect the size-dependent scattering at a specific depth within epithelium. Analysis of the scattering signal by use of Mie theory allows the extraction of scatterer size and size distribution-key parameters for precancer detection. The probe was evaluated in two tissue phantoms: polystyrene beads atop collagen gel and multiple layers of cancer cells atop collagen. We also present in vivo measurements in the oral cavity of normal volunteers. The sizes of scatterers extracted from the scattering spectra corresponded to independently measured values.

  13. Quantitative optical coherence elastography based on fiber-optic probe with integrated Fabry-Perot force sensor

    Science.gov (United States)

    Qiu, Yi; Wang, Yahui; Xu, Yiqing; Chandra, Namas; Haorah, James; Hubbi, Basil; Pfister, Bryan J.; Liu, Xuan

    2016-03-01

    Optical coherence tomography (OCT) is a versatile imaging technique and has great potential in tissue characterization for breast cancer diagnosis and surgical guidance. In addition to structural difference, cancerous breast tissue is usually stiffer compared to normal adipose breast tissue. However, previous studies on compression optical coherence elastography (OCE) are qualitative rather than quantitative. It is challenging to identify the cancerous status of tissue based on qualitative OCE results obtained from different measurement sessions or from different patients. Therefore, it is critical to develop technique that integrates structural imaging and force sensing, for quantitative elasticity characterization of breast tissue. In this work, we demonstrate a quantitative OCE (qOCE) microsurgery device which simultaneously quantifies force exerted to tissue and measures the resultant tissue deformation. The qOCE system is based on a spectral domain OCT engine operated at 1300 nm and a probe with an integrated Febry-Perot (FP) interferometric cavity at its distal end. The FP cavity is formed by the cleaved end of the lead-in fiber and the end surface of a GRIN lens which allows light to incident into tissue for structural imaging. The force exerted to tissue is quantified by the change of FP cavity length which is interrogated by a fiber-optic common-paths phase resolved OCT system with sub-nanometer sensitivity. Simultaneously, image of the tissue structure is acquired from photons returned from tissue through the GRIN lens. Tissue deformation is obtained through Doppler analysis. Tissue elasticity can be quantified by comparing the force exerted and tissue deformation.

  14. Measurement of Electron Density Using the Multipole Resonance Probe, Langmuir Probe and Optical Emission Spectroscopy in Low Pressure Plasmas with Different Electron Energy Distribution Functions

    Science.gov (United States)

    Oberberg, Moritz; Bibinov, Nikita; Ries, Stefan; Awakowicz, Peter; Institute of Electrical Engineering; Plasma Technology Team

    2016-09-01

    In recently publication, the young diagnostic tool Multipole Resonance Probe (MRP) for electron density measurements was introduced. It is based on active plasma resonance spectroscopy (APRS). The probe was simulated und evaluated for different devices. The geometrical and electrical symmetry simplifies the APRS model, so that the electron density can be easily calculated from the measured resonance. In this work, low pressure nitrogen mixture plasmas with different electron energy distribution functions (EEDF) are investigated. The results of the MRP measurement are compared with measurements of a Langmuir Probe (LP) and Optical Emission Spectroscopy (OES). Probes and OES measure in different regimes of kinetic electron energy. Both probes measure electrons with low kinetic energy (<10 eV), whereas the OES is influenced by electrons with high kinetic energy which are needed for transitions of molecule bands. By the determination of the absolute intensity of N2(C-B) and N2+(B-X)electron temperature and density can be calculated. In a non-maxwellian plasma, all plasma diagnostics need to be combined.

  15. Optical probing of spin-dependent interactions in II-VI semiconductor structures

    Energy Technology Data Exchange (ETDEWEB)

    Gaj, J.A.; Golnik, A.; Goryca, M.; Kossacki, P.; Kowalik, K.; Kudelski, A.; Maslana, W.; Nawrocki, M.; Pacuski, W.; Plochocka, P.; Senellart, P. [Institute of Experimental Physics, Warsaw University, Hoza 69, 00-681 Warszawa (Poland); Cibert, J.; Ferrand, D.; Tatarenko, S. [CNRS-CEA-UJF Joint Group ' ' Nanophysique et semiconducteurs' ' , Laboratoire de Spectrometrie Physique, BP 87, 38402 Saint Martin d' Heres Cedex (France); Karczewski, G.; Kossut, J.; Kutrowski, M. [Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warszawa (Poland); Krebs, O.; Lemaitre, A.; Voisin, P. [Laboratoire de Photonique et Nanostructures, CNRS, Route de Nozay, 91460 Marcoussis (France); Wojtowicz, T.

    2006-03-15

    We present a selection of optical experiments, providing information on several spin-dependent interactions in II-VI semiconductor structures. Exciton-exciton and exciton-carrier interactions were studied by time-resolved picosecond pump-probe measurements. Several examples of recent studies involving ion-carrier exchange interaction in quantum wells and layers are discussed, concerning the quest for room temperature ferromagnetic semiconductors, spin temperature of Mn ions in (Cd,Mn)Te quantum wells, and spin relaxation in such wells under pulsed magnetic field. Finally, anisotropic electron-hole exchange in semiconductor quantum dots is discussed in the context of efforts to obtain generation of entangled photon pairs in a biexciton-exciton cascade in a semiconductor quantum dot. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Optical Tweezers Array and Nimble Tweezers Probe Generated by Spatial- Light Modulator

    Science.gov (United States)

    Decker, Arthur J.; Jassemnejad, Baha; Seibel, Robin E.; Weiland, Kenneth E.

    2003-01-01

    An optical tweezers is being developed at the NASA Glenn Research Center as a visiblelight interface between ubiquitous laser technologies and the interrogation, visualization, manufacture, control, and energization of nanostructures such as silicon carbide (SiC) nanotubes. The tweezers uses one or more focused laser beams to hold micrometer-sized particles called tools (sometimes called tips in atomic-force-microscope terminology). A strongly focused laser beam has an associated light-pressure gradient that is strong enough to pull small particles to the focus, in spite of the oppositely directed scattering force; "optical tweezers" is the common term for this effect. The objective is to use the tools to create carefully shaped secondary traps to hold and assemble nanostructures that may contain from tens to hundreds of atoms. The interaction between a tool and the nanostructures is to be monitored optically as is done with scanning probe microscopes. One of the initial efforts has been to create, shape, and control multiple tweezers beams. To this end, a programmable spatial-light modulator (SLM) has been used to modify the phase of a laser beam at up to 480 by 480 points. One program creates multiple, independently controllable tweezer beams whose shapes can be tailored by making the SLM an adaptive mirror in an interferometer (ref. 1). The beams leave the SLM at different angles, and an optical Fourier transform maps these beams to different positions in the focal plane of a microscope objective. The following figure shows two arrays of multiple beams created in this manner. The patterns displayed above the beam array control the intensity-to-phase transformation required in programming the SLM. Three of the seven beams displayed can be used as independently controllable beams.

  17. Hyperspectral nanoscale imaging on dielectric substrates with coaxial optical antenna scan probes.

    Science.gov (United States)

    Weber-Bargioni, Alexander; Schwartzberg, Adam; Cornaglia, Matteo; Ismach, Ariel; Urban, Jeffrey J; Pang, Yuanjie; Gordon, Reuven; Bokor, Jeffrey; Salmeron, Miquel B; Ogletree, D Frank; Ashby, Paul; Cabrini, Stefano; Schuck, P James

    2011-03-09

    We have demonstrated hyperspectral tip-enhanced Raman imaging on dielectric substrates using linearly polarized light and nanofabricated coaxial antenna tips. A full Raman spectrum was acquired at each pixel of a 256 by 256 pixel contact-mode atomic force microscope image of carbon nanotubes grown on a fused silica microscope coverslip, allowing D and G mode intensity and D-mode peak shifts to be measured with ∼20 nm spatial resolution. Tip enhancement was sufficient to acquire useful Raman spectra in 50-100 ms. Coaxial scan probes combine the efficiency and enhanced, ultralocalized optical fields of plasmonically coupled antennae with the superior topographical imaging properties of sharp metal tips. The yield of the coaxial tip fabrication process is close to 100%, and the tips are sufficiently durable to support hours of contact-mode force microscope imaging. Our coaxial probes avoid the limitations associated with the "gap-mode" imaging geometry used in most tip-enhanced Raman studies to date, where a sharp metal tip is held ∼1 nm above a metallic substrate with the sample located in the gap.

  18. Biomedical Probes Based on Inorganic Nanoparticles for Electrochemical and Optical Spectroscopy Applications

    Directory of Open Access Journals (Sweden)

    Abdulhadee Yakoh

    2015-08-01

    Full Text Available Inorganic nanoparticles usually provide novel and unique physical properties as their size approaches nanometer scale dimensions. The unique physical and optical properties of nanoparticles may lead to applications in a variety of areas, including biomedical detection. Therefore, current research is now increasingly focused on the use of the high surface-to-volume ratios of nanoparticles to fabricate superb chemical- or biosensors for various detection applications. This article highlights various kinds of inorganic nanoparticles, including metal nanoparticles, magnetic nanoparticles, nanocomposites, and semiconductor nanoparticles that can be perceived as useful materials for biomedical probes and points to the outstanding results arising from their use in such probes. The progress in the use of inorganic nanoparticle-based electrochemical, colorimetric and spectrophotometric detection in recent applications, especially bioanalysis, and the main functions of inorganic nanoparticles in detection are reviewed. The article begins with a conceptual discussion of nanoparticles according to types, followed by numerous applications to analytes including biomolecules, disease markers, and pharmaceutical substances. Most of the references cited herein, dating from 2010 to 2015, generally mention one or more of the following characteristics: a low detection limit, good signal amplification and simultaneous detection capabilities.

  19. A fiber optic probe for measurement of an autonomic dysreflexia event on SCI patients

    Science.gov (United States)

    Ramella-Roman, J. C.; Hidler, J. M.

    2008-02-01

    Autonomic Dysreflexia (AD) is an inappropriate response of the sympathetic nervous system that often occurs in individuals with spinal cord injury (SCI ) at or above the sixth thoracic vertebrae (T6) level when a noxius stimulus is applied below the level of injury. An AD event can be put into motion by something as simple as an ingrown toenail or a full bladder, with symptoms such as headache, elevated blood pressure, reduced heart rate, decreases in blood flow below the level of injury, and in extreme cases, stroke. We have developed a quantitative method of measuring skin oxygen levels during AD using a fiber optics based probe. Two such probes were located above and below the injury level (on the patient forearm and thigh respectively) and were connected to a dual channel spectrophotometer. Oxygen saturation was calculated using the reflectance spectra and an algorithm based on melanin and hemoglobin absorption. We found that during an AD event, the amount of oxygen in the skin below the injury level drops by as much as 40%, while above the injury level skin oxygenation remains constant. Additionally, we observed elevated persperation levels below the injury level. We hypothesize that the combination of AD-related ischemia with pressure related ischemia and increased perspiration places individuals with injury level at T6 or above at significant risk for developing a pressure sore below the injury site.

  20. Fiber-based modulated optical reflectance configuration allowing for offset pump and probe beams

    Science.gov (United States)

    Fleming, A.; Folsom, C.; Jensen, C.; Ban, H.

    2016-12-01

    A new fiber-based modulated optical reflectance configuration is developed in this work. The technique maintains the fiber-based heating laser (pump) and detection laser (probe) in close proximity at a fixed separation distance in a ceramic ferrule. The pump beam periodically heats the sample inducing thermal waves into the sample. The probe beam measures the temperature response at a known distance from the pump beam over a range of heating modulation frequencies. The thermal diffusivity of the sample may be calculated from the phase response between the input heat flux and the temperature response of a sample having a reflective surface. The unique measurement configuration is ideal for in situ measurements and has many advantages for laboratory-based systems. The design and development of the system are reported along with theoretical justification for the experimental design. The thermal diffusivities of Ge and SiC are measured and found to be within 10% of reported literature values. The diffusivity for SiO2 is measured with a relative difference of approximately 100% from the literature value when the ferrule is in contact with the sample. An additional measurement was made on the SiO2 sample with the ferrule not in contact resulting in a difference of less than 2% from the literature value. The difference in the SiO2 measurement when the ferrule is in contact with the sample is likely due to a parallel heat transfer path through the dual-fiber ferrule assembly.

  1. Fourier transform infrared imaging and infrared fiber optic probe spectroscopy identify collagen type in connective tissues.

    Directory of Open Access Journals (Sweden)

    Arash Hanifi

    Full Text Available Hyaline cartilage and mechanically inferior fibrocartilage consisting of mixed collagen types are frequently found together in repairing articular cartilage. The present study seeks to develop methodology to identify collagen type and other tissue components using Fourier transform infrared (FTIR spectral evaluation of matrix composition in combination with multivariate analyses. FTIR spectra of the primary molecular components of repair cartilage, types I and II collagen, and aggrecan, were used to develop multivariate spectral models for discrimination of the matrix components of the tissues of interest. Infrared imaging data were collected from bovine bone, tendon, normal cartilage, meniscus and human repair cartilage tissues, and composition predicted using partial least squares analyses. Histology and immunohistochemistry results were used as standards for validation. Infrared fiber optic probe spectral data were also obtained from meniscus (a tissue with mixed collagen types to evaluate the potential of this method for identification of collagen type in a minimally-invasive clinical application. Concentration profiles of the tissue components obtained from multivariate analysis were in excellent agreement with histology and immunohistochemistry results. Bone and tendon showed a uniform distribution of predominantly type I collagen through the tissue. Normal cartilage showed a distribution of type II collagen and proteoglycan similar to the known composition, while in repair cartilage, the spectral distribution of both types I and II collagen were similar to that observed via immunohistochemistry. Using the probe, the outer and inner regions of the meniscus were shown to be primarily composed of type I and II collagen, respectively, in accordance with immunohistochemistry data. In summary, multivariate analysis of infrared spectra can indeed be used to differentiate collagen type I and type II, even in the presence of proteoglycan, in

  2. Multimodal optical biopsy probe to improve the safety and diagnostic yield of brain needle biopsies (Conference Presentation)

    Science.gov (United States)

    Desroches, Joannie; Pichette, Julien; Goyette, Andréanne; Tremblay, Marie-Andrée.; Jermyn, Michael; Petrecca, Kevin; Leblond, Frédéric

    2016-03-01

    Brain needle biopsy (BNB) is performed to collect tissue when precise neuropathological diagnosis is required to provide information about tumor type, grade, and growth patterns. The principal risks associated with this procedure are intracranial hemorrhage (due to clipping blood vessels during tissue extraction), incorrect tumor typing/grading due to non-representative or non-diagnostic samples (e.g. necrotic tissue), and missing the lesion. We present an innovative device using sub-diffuse optical tomography to detect blood vessels and Raman spectroscopy to detect molecular differences between tissue types, in order to reduce the risks of misdiagnosis, incorrect tumour grading, and non-diagnostic samples. The needle probe integrates optical fibers directly onto the external cannula of a commercial BNB needle, and can perform measurements for both optical techniques through the same fibers. This integrated optical spectroscopy system uses diffuse reflectance signals to perform a 360-degree reconstruction of the tissue adjacent to the biopsy needle, based on the optical contrast associated with hemoglobin light absorption, thereby localizing blood vessels. Raman spectra measurements are also performed interstitially for tissue characterization. A detailed sensitivity of the system is presented to demonstrate that it can detect absorbers with diameters biopsy needle core, for bulk optical properties consistent with brain tissue. Results from animal experiments are presented to validate blood vessel detection and Raman spectrum measurement without disruption of the surgical workflow. We also present phantom measurements of Raman spectra with the needle probe and a comparison with a clinically validated Raman spectroscopy probe.

  3. Development of disposable membrane hydrophones for a frequency range from 1MHz to 10MHz.

    Science.gov (United States)

    Lee, Jae-Wan; Ohm, Won-Suk; Kim, Yong-Tae

    2017-11-01

    A method for fabricating disposable membrane hydrophones is presented. The disposable hydrophones are intended for onetime use in such damaging environments as chemically contaminating fluids and high-amplitude (peak amplitude ∼100MPa) shock wave fields, where the use of commercial membrane hydrophones is not recommended. Fabrication of a hydrophone is done using only off-the-shelf components and hand tools, which translates into ease of fabrication and orders-of-magnitude reduction in unit cost. In particular, poling and sputtering, the two processes that are chiefly responsible for the cost and difficulty associated with the conventional fabrication method, are replaced with the use of pre-poled polyvinylidene fluoride (PVDF) films and polyethylene terephthalate (PET)-coated aluminum foils, respectively. Despite the seemingly crude construction, these disposable hydrophones can exhibit voltage sensitivity response that compares favorably with that of commercial hydrophones. For example, one prototype having a 2mm×2mm active element shows the end-of-cable voltage sensitivity of -270 (±1.9) dB re 1V/μPa over the frequency range of 1-10MHz. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Are hydrophones of diameter 0.5 mm small enough to characterise diagnostic ultrasound equipment?

    Science.gov (United States)

    Smith, R A

    1989-11-01

    A basic requirement for making measurements of medical ultrasonic fields using small sensors is that the sensor should be smaller than the ultrasonic wavelength. Until recently, the smallest commercially-available PVDF membrane hydrophone sensor had a diameter of 0.5 mm, which is larger that the wavelength in water for frequencies above 3 MHz. Thus many measurements have been made with hydrophones which are strictly too large. In this situation, averaging of the acoustic pressure over the active element can cause an underestimate of the spatial-peak acoustic pressure level. In the past, this error was estimated using theoretical models of the beam profile. However, these models make basic assumptions about both the ultrasonic field and the directional response of the hydrophone--assumptions which may not be valid in all diagnostic ultrasonic fields. GEC-Marconi membrane hydrophones with diameters as small as 0.1 mm have now been used to check these theories for diagnostic fields. This paper shows that the error resulting from the use of too large a hydrophone can be up to three times that predicted by current theories. Possible new correction methods are discussed for use in some situations. In other cases the errors can only be reduced by using these new hydrophones, particularly when the acoustic waveform is distorted by nonlinear propagation.

  5. Development of cup-shaped micro-electromechanical systems-based vector hydrophone

    Science.gov (United States)

    Xu, Wei; Liu, Yuan; Zhang, Guojun; Wang, Renxin; Xue, Chenyang; Zhang, Wendong; Liu, Jun

    2016-09-01

    Similar to the vital performance factors, the receiving sensitivity and the bandwidth exist interactively in the micro-electromechanical systems (MEMS)-based vector hydrophones. Some existing methods can improve the sensitivity of the hydrophone, but these improvements are usually gained at a cost of the bandwidth. However, the cup-shaped MEMS vector hydrophone that is presented in this paper can improve its sensitivity while retaining a sufficient bandwidth. The cup-shaped structure acts as a new sensing unit in the MEMS vector hydrophone, replacing the bionic columnar hair that was previously used for sensing. The relationships between the parameters of the cup-shaped structure and the sensitivity of the vector hydrophone were determined by a theoretical deduction. In addition, simulation analyses were performed, and optimized structural parameters were obtained in this work. ANSYS 15.0 simulation was used to derive the optimum characteristics for the cup-shaped structure. The results of the calibration experiments showed that the sensitivity reached up to -188.5 dB (gain of 40 dB, 1 kHz, 0 dB@1 V/μPa), and the bandwidth was in the 20 Hz-1 kHz range, which is sufficient for an underwater acoustic detection at low frequencies. This work has, thus, proved that the cup-shaped vector hydrophone has superior properties for the engineering applications.

  6. Fiber-optical sensor with miniaturized probe head and nanometer accuracy based on spatially modulated low-coherence interferogram analysis.

    Science.gov (United States)

    Depiereux, Frank; Lehmann, Peter; Pfeifer, Tilo; Schmitt, Robert

    2007-06-10

    Fiber-optical sensors have some crucial advantages compared with rigid optical systems. They allow miniaturization and flexibility of system setups. Nevertheless, optical principles such as low-coherence interferometry can be realized by use of fiber optics. We developed and realized an approach for a fiber-optical sensor, which is based on the analysis of spatially modulated low-coherence interferograms. The system presented consists of three units, a miniaturized sensing probe, a broadband fiber-coupled light source, and an adapted Michelson interferometer, which is used as an optical receiver. Furthermore, the signal processing procedure, which was developed for the interferogram analysis in order to achieve nanometer measurement accuracy, is discussed. A system prototype has been validated thoroughly in different experiments. The results approve the accuracy of the sensor.

  7. Optically induced lattice dynamics probed with ultrafast x-ray diffraction

    Science.gov (United States)

    Lee, H. J.; Workman, J.; Wark, J. S.; Averitt, R. D.; Taylor, A. J.; Roberts, J.; McCulloch, Q.; Hof, D. E.; Hur, N.; Cheong, S.-W.; Funk, D. J.

    2008-04-01

    We have studied the picosecond lattice dynamics of optically pumped hexagonal LuMnO3 by using ultrafast x-ray diffraction. The results show a shift and broadening of the diffraction curve due to the stimulated lattice expansion. To understand the transient response of the lattice, the measured time- and angle-resolved diffraction curves are compared to a theoretical calculation based on the dynamical diffraction theory of coherent phonon propagation modified for the hexagonal crystal structure of LuMnO3 . Our simulations reveal that a large coupling coefficient (c13) between the a-b plane and the c axis is required to fit the data. Though we interpret the transient response within the framework of thermal coherent phonons, we do not exclude the possibility of strong nonthermal coupling of the electronic excitation to the atomic framework. We compare this result to our previous coherent phonon studies of LuMnO3 in which we used optical pump-probe spectroscopy.

  8. Real-time optical detection of methicillin-resistant Staphylococcus aureus using lytic phage probes.

    Science.gov (United States)

    Guntupalli, Rajesh; Sorokulova, Iryna; Krumnow, April; Pustovyy, Oleg; Olsen, Eric; Vodyanoy, Vitaly

    2008-09-15

    Staphylococcus aureus (S. aureus)-specific bacteriophage was used as a probe for detection of methicillin-resistant S. aureus (MRSA) in aqueous solution using a novel optical method. Biorecognition phage monolayers transferred to glass substrates using Langmuir-Blodgett (LB) technique were exposed individually to MRSA in solution at logarithmic concentrations ranging from 10(6) to 10(9)cfu/ml, and observed for real-time binding using a CytoViva optical light microscope system. Results indicate that LB monolayers possessed high levels of elasticity (K), measuring 22 and 29 mN/m for 10(9) and 10(11)pfu/ml phage concentrations, respectively. Near-instantaneous MRSA-phage binding produced 33+/-5%, 10+/-1%, 1.1+/-0.1%, and 0.09+/-0.01% coverage of the substrate that directly correlated to a decrease in MRSA concentrations of 10(9), 10(8), 10(7), and 10(6)cfu/ml. The exclusive selectivity of phage monolayers was verified with Salmonella enterica subsp. enterica serovar typhimurium (S. typhimurium) and Bacillus subtilis.

  9. Optical fibre probes in the measurement of scattered light: Application for sensing turbidity

    Indian Academy of Sciences (India)

    M R Sheno

    2014-01-01

    Optical fibre probes or optrodes often form the heart of multimode fibre-based measurements and sensors. An optrode usually comprises a bundle of multimode fibres, out of which one or more fibres are used for irradiating the sample, and the remaining fibres are used to collect the light reflected/scattered/fluoresced from the sample containing the measurand(s). The so-collected light carries the characteristic signature of the measurand. Here we present our work on the design and realization of optrodes for the measurement of scattered light from liquid samples. Optical properties of a solution are usually characterized by the parameters absorption coefficient $_a$, scattering coefficient $_s$, and anisotropy factor . We have developed a simple method to determine $_a$, $_s$, and , of a turbid medium, and a Monte–Carlo model was used to simulate the light scattering from the turbid medium. As an application, we describe the development of a turbidity sensor that has been designed and realized by employing an optrode in conjunction with a concave mirror. The estimation of turbidity is done on the basis of total interaction, by considering scattering and absorption of light from the sample solution. Details of the experiments and results are presented here.

  10. Chiral, J-Aggregate-Forming Dyes for Alternative Signal Modulation Mechanisms in Self-Immolative Enzyme-Activatable Optical Probes.

    Science.gov (United States)

    Sloniec-Myszk, Jagoda; Resch-Genger, Ute; Hennig, Andreas

    2016-02-11

    Enzyme-activatable optical probes are important for future advances in cancer imaging, but may easily suffer from low signal-to-background ratios unless not optimized. To address this shortcoming, numerous mechanisms to modulate the fluorescence signal have been explored. We report herein newly synthesized probes based on self-immolative linkers containing chiral J-aggregate-forming dyes. Signal modulation by formation of chiral J-aggregates is yet unexplored in optical enzyme probe design. The comprehensive characterization of the probes by absorption, CD, fluorescence, and time-resolved fluorescence spectroscopy revealed dye-dye interactions not observed for the free dyes in solution as well as dye-protein interactions with the enzyme. This suggested that J-aggregate formation is challenging to achieve with current probe design and that interactions of the dyes with the enzyme may interfere with achieving high signal-to-background ratios. The detailed understanding of the interactions provided herein provides valuable guidelines for the future design of similar probes.

  11. Method for measuring self-noise of vector hydrophones

    Science.gov (United States)

    Li, Zhi; Chen, Hongjuan

    2017-09-01

    The Vector Hydrophone (VH) is widely used to remotely detect underwater targets. Accurately measuring the self-noise of the VH provides an important basis for evaluating the performance of the detection system in which it is utilized, since the ability to acquire weak signals is determined by the VH self-noise level. To accurately measure the VH self-noise level in actual working conditions, the Dual-channel Transfer Function Method (DTFM) is proposed to reduce ambient background noise interference. In this paper, the underlying principles of DTFM in reducing ambient background noise is analyzed. The numerical simulations to determine the influence of ambient background noise, and the sensitivity difference of the two VHs on the measurement results are studied. The results of measuring the VH self-noise level in a small laboratory water tank by using DTMF indicate that ambient background noise interference can be reduced effectively by employing DTMF, more accurate self-noise level can be obtained as well. The DTMF provides an effective method for accurately measuring the self-noise level of VHs and also provides technical support for the practical application of the VH in underwater acoustics.

  12. Photoacoustic endoscopy probe using a coherent fibre-optic bundle and Fabry-Pérot ultrasound sensor (Conference Presentation)

    Science.gov (United States)

    Ansari, Rehman; Beard, Paul C.; Zhang, Edward Z.; Desjardins, Adrien E.

    2016-03-01

    There is considerable interest in the development of photoacoustic endoscopy (PAE) probes for the clinical assessment of pathologies in the gastrointestinal (GI) tract, guiding minimally invasive laparoscopic surgeries and applications in foetal medicine. However, most previous PAE probes integrate mechanical scanners and piezoelectric transducers at the distal end which can be technically complex, expensive and pose challenges in achieving the necessary level of miniaturisation. We present two novel all-optical forward-viewing endoscopic probes operating in widefield tomography mode that have the potential to overcome these limitations. In one configuration, the probe comprises a transparent 40 MHz Fabry-Pérot ultrasound sensor deposited at the tip of a rigid, 3 mm diameter coherent fibre-optic bundle. In this way, the distal end of coherent fibre bundle acts as a 2D array of wideband ultrasound detectors. In another configuration, an optical relay is used between the distal end face of flexible fibre bundle and the Fabry-Pérot sensor to enlarge the lateral field of view to 6 mm x 6 mm. In both configurations, the pulsed excitation laser beam is full-field coupled into the fibre bundle at the proximal end for uniform backward-mode illumination of the tissue at the probe tip. In order to record the photoacoustic waves arriving at the probe tip, the proximal end of the fibre bundle is optically scanned in 2D with a CW wavelength-tunable interrogation laser beam thereby interrogating different spatial points on the sensor. A time-reversal image reconstruction algorithm was used to reconstruct a 3D image from the detected signals. The 3D field of view of the flexible PAE probe is 6 mm x 6 mm x 6 mm and the axial and lateral spatial resolution is 30 µm and 90 µm, respectively. 3D imaging capability is demonstrated using tissue phantoms, ex vivo tissues and in vivo. To the best of our knowledge, this is the first forward-viewing implementation of a photoacoustic

  13. Calibration of Hydrophone Stations: Lessons Learned from the Ascension Island Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Harben, P E; Rodgers, A J

    2000-07-11

    Calibration of hydroacoustic stations for nuclear explosion monitoring is important for increasing monitoring capability and confidence from newly installed stations and from existing stations. Calibration of hydroacoustic stations is herein defined as the near-field precision location of the hydrophones and determination of the amplitude response; and the regional-scale calibration of acoustic traveltimes, bathymetric shadowing, diffraction, and reflection as recorded at a particular station. An important type of calibration not considered here is ocean-basin-scale calibration of a hydroacoustic monitoring system. To understand how to best conduct hydroacoustic station calibrations, an experiment was conducted in May 1999 at Ascension Island in the South Atlantic Ocean. The experiment made use of a British oceanographic research vessel towing an airgun array and collected data over three MILS hydrophones that were in use by the National Data Center and the International Data Center. From the towed airgun data we were able to determine the location for each of the three hydrophones to accuracy better than 100 meters in latitude, longitude, and depth. The agreement with the nominal locations was excellent in depth and to within 1 km in latitude and longitude. The depths determined for the hydrophones and the ocean bottom depths determined from the ship's sonar system force the conclusion that all three hydrophones are located at or near the ocean bottom. Amplitude frequency response of the hydrophones was also calibrated using a calibrated temporarily deployed hydrophone to determine the airgun source function. With the source function known, the amplitude and phase response of the hydrophones could be deconvolved from the recorded waveforms provided a ''pure'' source waveform arrival is identified on the recording. Unfortunately, since the hydrophones are located near the ocean bottom, the recording is contaminated by reflections and

  14. Limitations of the commonly used simplified laterally uniform optical fiber probe-tissue interface in Monte Carlo simulations of diffuse reflectance.

    Science.gov (United States)

    Naglič, Peter; Pernuš, Franjo; Likar, Boštjan; Bürmen, Miran

    2015-10-01

    Light propagation models often simplify the interface between the optical fiber probe tip and tissue to a laterally uniform boundary with mismatched refractive indices. Such simplification neglects the precise optical properties of the commonly used probe tip materials, e.g. stainless steel or black epoxy. In this paper, we investigate the limitations of the laterally uniform probe-tissue interface in Monte Carlo simulations of diffuse reflectance. In comparison to a realistic probe-tissue interface that accounts for the layout and properties of the probe tip materials, the simplified laterally uniform interface is shown to introduce significant errors into the simulated diffuse reflectance.

  15. Oxidation of hydrogen-passivated silicon surfaces by scanning near-field optical lithography using uncoated and aluminum-coated fiber probes

    DEFF Research Database (Denmark)

    Madsen, Steen; Bozhevolnyi, Sergey I.; Birkelund, Karen

    1997-01-01

    Optically induced oxidation of hydrogen-passivated silicon surfaces using a scanning near-field optical microscope was achieved with both uncoated and aluminum-coated fiber probes. Line scans on amorphous silicon using uncoated fiber probes display a three-peak profile after etching in potassium...

  16. Tip-enhanced Raman spectroscopy with silver-coated optical fiber probe in reflection mode for investigating multiwall carbon nanotubes.

    Science.gov (United States)

    Wang, Rui; Wang, Jia; Hao, Fenghuan; Zhang, Mingqian; Tian, Qian

    2010-04-01

    We developed a tip-enhanced Raman spectrometer (TERS) with reflection mode. The instrument, with a scanning shear-force microscope (ShFM) and a side-illumination Raman spectroscope, can overcome the diffraction limit and has high sensitivity. A chemical method to fabricate optical fiber probes with Ag coating is proposed. The local electromagnetic responses of the silver-coated optical fiber probe are numerically analyzed by the finite-difference time-domain method, and the excitation wavelength is optimized to resonate with the localized surface plasmons (LSP) of the probe tip. The instrument is applied to investigate a single multiwall carbon nanotube. The experiment results indicate that our TERS instrument has a spatial resolution better than 70 nm, and the enhancement factor is about 5 x 10(3).

  17. A novel electro-optical pump-probe system for bioelectromagnetic investigations

    Science.gov (United States)

    De Angelis, Annalisa; Couderc, Vincent; Leproux, Philippe; Labruyère, Alexis; Tonello, Alessandro; El Amari, Saad; Arnaud-Cormos, Delia; Leveque, Philippe

    2012-10-01

    In the area of bioelectromagnetic studies there is a growing interest to understand the mechanisms leading to nanosecond electric fields induced electroporation. Real-time imaging techniques at molecular level could probably bring further advances on how electric fields interact with living cells. However the investigations are limited by the present-day lack of these kinds of advanced instrumentations. In this context, we present an innovative electro-optical pump-probe system. The aim of our project is to provide a performing and compact device for electrical stimulation and multiplex Coherent anti-Stokes Raman Scattering (M-CARS) imaging of biological cells at once. The system consists of a 1064 nm sub-nanosecond laser source providing both a monochromatic pump and a polychromatic Stokes optical beam used in a CARS process, as well as the trigger beam for the optoelectronic switching-based electrical pulse generator. The polychromatic Stokes beam (from 600 to 1700 nm) results from a supercontinuum generation in a photonic crystal fiber (PCF). A detailed spectro-temporal characterization of such a broadband spectrum shows the impact of the nonlinear propagation in the fiber on the Stokes wave. Despite the temporal distortions observable on Stokes pulse profiles, their spectral synchronization with the pump pulse remains possible and efficient in the interesting region between 1100 nm and 1700 nm. The electrical stimulation device consists of a customized generator combining microstrip-line technology and laser-triggered photoconductive semiconductor switches. Our experimental characterization highlights the capability for such a generator to control the main pulse parameters (profile, amplitude and duration) and to be easily synchronized with the imaging system. We finally test and calibrate the system by means of a KDP crystal. The preliminary results suggest that this electro-optical system provides a suitable tool for real-time investigation of

  18. Optomechanical oscillator pumped and probed by optically two isolated photonic crystal cavity systems.

    Science.gov (United States)

    Tian, Feng; Sumikura, Hisashi; Kuramochi, Eiichi; Taniyama, Hideaki; Takiguchi, Masato; Notomi, Masaya

    2016-11-28

    Optomechanical control of on-chip emitters is an important topic related to integrated all-optical circuits. However, there is neither a realization nor a suitable optomechanical structure for this control. The biggest obstacle is that the emission signal can hardly be distinguished from the pump light because of the several orders' power difference. In this study, we designed and experimentally verified an optomechanical oscillation system, in which a lumped mechanical oscillator connected two optically isolated pairs of coupled one-dimensional photonic crystal cavities. As a functional device, the two pairs of coupled cavities were respectively used as an optomechanical pump for the lumped oscillator (cavity pair II, wavelengths were designed to be within a 1.5 μm band) and a modulation target of the lumped oscillator (cavity pair I, wavelengths were designed to be within a 1.2 μm band). By conducting finite element method simulations, we found that the lumped-oscillator-supported configurations of both cavity pairs enhance the optomechanical interactions, especially for higher order optical modes, compared with their respective conventional side-clamped configurations. Besides the desired first-order in-plane antiphase mechanical mode, other mechanical modes of the lumped oscillator were investigated and found to possibly have optomechanical applications with a versatile degree of freedom. In experiments, the oscillator's RF spectra were probed using both cavity pairs I and II, and the results matched those of the simulations. Dynamic detuning of the optical spectrum of cavity pair I was then implemented with a pumped lumped oscillator. This was the first demonstration of an optomechanical lumped oscillator connecting two optically isolated pairs of coupled cavities, whose biggest advantage is that one cavity pair can be modulated with an lumped oscillator without interference from the pump light in the other cavity pair. Thus, the oscillator is a suitable

  19. Research on the best measurement situation between optical probe and tissue surfaces in non-invasive detection

    Science.gov (United States)

    Yu, Xuyao; Liu, Rong; Yu, Hui; Wang, Jiao; Wang, Jun; Xu, Kexin

    2016-11-01

    Near-infrared spectroscopy is often used for the non-invasive detection of composition in the human body, such as that of blood glucose and haemoglobin, due to its high penetration depth into tissues. Although it is feasible to position the optical probe precisely, contact situation between probe and human tissues is a difficult problem to determine because of physiological tremor and mechanical performance of bio-soft tissue. Here, we proposed a novel estimation method for the situation between the optical probe and tissue surfaces based on the dynamic auto-correlation matrix of two-dimensional correlation spectroscopy (2DCOS) and radar chart. The diffuse reflectance spectra from the left palm of 4 healthy volunteers were collected while the optical probe gradually approached and pressed bio-tissues with a custom-design controlling device. 2DCOS in the wavelength with lower absorption (1000-1400 nm) was calculated under the perturbation of relative-distance and contact pressure between the optical probe and tissue surface. The synchronous 2DCOS showed that the surface reflection and diffuse reflectance were greatly affected by the contact conditions in 1100 nm, 1220 nm, and 1300 nm. Then the dynamic auto-correlation matrix of 2DCOS was established for the adjacent spectra, and the significant difference wavelengths were used to build radar charts to determine the critical contact situation visually. Results showed that the maximum variations of dynamic auto-correlation matrix appeared at near 1300 nm, and the relative distance between the probe and tissue corresponding to the critical contact state can be easily observed with radar charts with 0.25 mm uncertainty, which was consistent with the self-feeling of each volunteer. So this method can be applied to exactly determine the optimal measurement status for the non-invasive body composition detection in vivo. It is important for the design of human-machine interface and the accuracy improvement of body

  20. Evaluation of permeability of Nojima fault by hydrophone VSP; Hydrophone VSP ni yoru Nojima danso no tosuisei hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Kiguchi, T.; Ito, H.; Kuwahara, Y.; Miyazaki, T. [Geological Survey of Japan, Tsukuba (Japan)

    1996-05-01

    The multi-offset hydrophone VSP experiments were carried out using a 750m deep borehole as the oscillation receiver, which penetrates the Nojima fault, to detect water-permeable cracks and evaluate their characteristics. Soil around the borehole is of granodiorite, and fault clay is found at a depth in a range from 623 to 624m. A total of 4 dynamite tunnels were provided around the borehole as the focus. The VSP results show that the tube waves are generated at 22 depths, including the depth at which fault clay is found. However, these waves are generated at only 6 depths in an approximately 150m long fracture zone, suggesting that the cracks in the zone are not necessarily permeable. It is also found that crack angle determined by the analysis of tube waves almost coincides with that of fault clay determined by the core, BHTV and FMI, and that permeability is of the order of 100md at a depth of fault clay or shallower. 3 refs., 2 figs., 2 tabs.

  1. Fiber optic probe enabled by surface-enhanced Raman scattering for early diagnosis of potential acute rejection of kidney transplant

    Science.gov (United States)

    Chi, Jingmao; Chen, Hui; Tolias, Peter; Du, Henry

    2014-06-01

    We have explored the use of a fiber-optic probe with surface-enhanced Raman scattering (SERS) sensing modality for early, noninvasive and, rapid diagnosis of potential renal acute rejection (AR) and other renal graft dysfunction of kidney transplant patients. Multimode silica optical fiber immobilized with colloidal Ag nanoparticles at the distal end was used for SERS measurements of as-collected urine samples at 632.8 nm excitation wavelength. All patients with abnormal renal graft function (3 AR episodes and 2 graft failure episodes) who were clinically diagnosed independently show common unique SERS spectral features in the urines collected just one day after transplant. SERS-based fiber-optic probe has excellent potential to be a bedside tool for early diagnosis of kidney transplant patients for timely medical intervention of patients at high risk of transplant dysfunction.

  2. The Backscatter Cloud Probe – a compact low-profile autonomous optical spectrometer

    Directory of Open Access Journals (Sweden)

    K. Beswick

    2013-08-01

    Full Text Available A compact (500 cm3, lightweight (500 g, near-field, single particle backscattering optical spectrometer is described that mounts flush with the skin of an aircraft and measures the concentration and optical equivalent diameter of particles from 5 to 75 μm. The Backscatter Cloud Probe (BCP was designed as a real-time qualitative cloud detector primarily for data quality control of trace gas instruments developed for the climate monitoring instrument packages that are being installed on commercial passenger aircraft as part of the European Union In-Service Aircraft for a Global Observing System (IAGOS program (http://www.iagos.org/. Subsequent evaluations of the BCP measurements on a number of research aircraft, however, have revealed it capable of delivering quantitative particle data products including size distributions, liquid water content and other information on cloud properties. We demonstrate the instrument's capability for delivering useful long-term climatological information, across a wide range of environmental conditions. The BCP has been evaluated by comparing its measurements with those from other cloud particle spectrometers on research aircraft and several BCPs are currently flying on commercial A340/A330 Airbus passenger airliners. The design and calibration of the BCP is described in this presentation, along with an evaluation of measurements made on the research and commercial aircraft. Comparisons of the BCP with two other cloud spectrometers, the Cloud Droplet Probe (CDP and the Cloud and Aerosol Spectrometer (CAS, show that the BCP size distributions agree well with those from the other two, given the intrinsic limitations and uncertainties related to the three instruments. Preliminary results from more than 7000 h of airborne measurements by the BCP on two Airbus A-340s operating on routine global traffic routes (one Lufthansa, the other China Airlines show that more than 340 h of cloud data have been recorded at normal

  3. Ultrahigh resolution endoscopic spectral domain optical coherence tomography with a tiny rotary probe driven by a hollow ultrasonic motor

    Science.gov (United States)

    Zhang, Ning; Chen, Tianyuan; Huo, Tiancheng; Wang, Chengming; Zheng, Jing-gao; Zhou, Tieying; Xue, Ping

    2013-03-01

    This paper proposes a novel rotary endoscopic probe for spectral-domain optical coherence tomography (SD-OCT). The probe with a large N.A. objective lens is driven by an ultra-small hollow rectangular ultrasonic motor for circular scanning. Compared to the conventional driven techniques, the hollow ultrasonic motor enables the fiber to pass through its inside. Therefore the fiber, the objective lens and the motor are all at the same side. This enables 360 degree unobstructed imaging without any shadow resulted from power wire as in the conventional motor-driven endoscopic OCT. Moreover, it shortens the length of the rigid tip and enhances the flexibility of the probe. Meanwhile, the ultrasonic motor is robust, simple, quiet and of high torque, very suitable for OCT endoscopic probe. The side length of the motor is 0.7 mm with 5mm in length. The outer diameter of the probe is 1.5mm. A significant improvement in the lateral resolution is demonstrated due to the novel design of the objective lens. A right-angle lens is utilized instead of the traditional right-angle prism as the last optics close to the sample, leading to a reduction of the working distance and an enlargement of the N.A. of the objective lens. It is demonstrated that the endoscopic SD-OCT system achieves an axial resolution of ~7μm, a lateral resolution of ~6μm and a SNR of ~96dB.

  4. Probing iron spin state by optical absorption in laser-heated diamond anvil cell

    Science.gov (United States)

    Lobanov, S.; Goncharov, A. F.; Holtgrewe, N.; Lin, J. F.

    2015-12-01

    Pressure-induced spin-pairing transitions in iron-bearing minerals have been in the focus of geophysical studies1. Modern consensus is that iron spin state in the lower mantle is a complex function of crystal structure, composition, pressure, and temperature. Discontinuities in physical properties of lower mantle minerals have been revealed over the spin transition pressure range, but at room temperature. In this work, we have used a supercontinuum laser source and an intensified CCD camera to probe optical properties of siderite, FeCO3, and post-perovskite, Mg0.9Fe0.1SiO3, across the spin transition in laser-heated diamond anvil cell. Synchronously gating the CCD with the supercontinuum pulses (Fig. 1A) allowed diminishing thermal background to ~8.3*10-4. Utilizing the experimental setup we infer the spin state of ferrous iron in siderite at high pressure and temperature conditions (Fig. 1B). Similar behavior is observed for low spin ferric iron in post-perovskite at 130 GPa indicating that all iron in post-perovskite is high spin at lower mantle conditions. Also, our experimental setup holds promise for measuring radiative thermal conductivity of mantle minerals at relevant mantle conditions. Figure 1. (A) Timing of the optical absorption measurements at high temperature. (B) High temperature siderite absorption spectra at 45 GPa. Before heating and quenched after 1300 K spectra are shown in light and dark blue, respectively. Green and red curves are absorption spectra at 1200 K and 1300 K, respectively. Spectra shown in black represent room temperature absorption data on HS (43 GPa) and LS (45.5 GPa) siderite after Lobanov et al., 2015, shown for comparison.

  5. Influence of the probe-sample interaction on scanning near-field optical microscopic images in the far field

    Institute of Scientific and Technical Information of China (English)

    Li Zhi; Zhang Jia-Sen; Yang Jing; Gong Qi-Huang

    2006-01-01

    We have studied the influence of probe-sample interaction in a scanning near-field optical microscopy (SNOM) in the far field by using samples with a step structure. For a sample with a step height of ~λ/4, the SNOM image contrast between the two sides of the step changes periodically at different scan heights. For a step height of ~λ/2, the image contrast remains approximately the same. The probe-sample interaction determines the SNOM image contrast here. The influence of different refractive indices of the sample has been also analysed by using a simple theoretical model.

  6. Next generation of optical diagnostics for bladder cancer using probe-based confocal laser endomicroscopy

    Science.gov (United States)

    Liu, Jen-Jane; Chang, Timothy C.; Pan, Ying; Hsiao, Shelly T.; Mach, Kathleen E.; Jensen, Kristin C.; Liao, Joseph C.

    2012-02-01

    Real-time imaging with confocal laser endomicroscopy (CLE) probes that fit in standard endoscopes has emerged as a clinically feasible technology for optical biopsy of bladder cancer. Confocal images of normal, inflammatory, and neoplastic urothelium obtained with intravesical fluorescein can be differentiated by morphologic characteristics. We compiled a confocal atlas of the urinary tract using these diagnostic criteria to be used in a prospective diagnostic accuracy study. Patients scheduled to undergo transurethral resection of bladder tumor underwent white light cystoscopy (WLC), followed by CLE, and histologic confirmation of resected tissue. Areas that appeared normal by WLC were imaged and biopsied as controls. We imaged and prospectively analyzed 135 areas in 57 patients. We show that CLE improves the diagnostic accuracy of WLC for diagnosing benign tissue, low and high grade cancer. Interobserver studies showed a moderate level of agreement by urologists and nonclinical researchers. Despite morphologic differences between inflammation and cancer, real-time differentiation can still be challenging. Identification of bladder cancer-specific contrast agents could provide molecular specificity to CLE. By using fluorescently-labeled antibodies or peptides that bind to proteins expressed in bladder cancer, we have identified putative molecular contrast agents for targeted imaging with CLE. We describe one candidate agent - anti-CD47 - that was instilled into bladder specimens. The tumor and normal urothelium were imaged with CLE, with increased fluorescent signal demonstrated in areas of tumor compared to normal areas. Thus, cancer-specificity can be achieved using molecular contrast agents ex vivo in conjunction with CLE.

  7. Probing matrix and tumor mechanics with in situ calibrated optical trap based active microrheology

    Science.gov (United States)

    Staunton, Jack Rory; Vieira, Wilfred; Tanner, Kandice; Tissue Morphodynamics Unit Team

    Aberrant extracellular matrix deposition and vascularization, concomitant with proliferation and phenotypic changes undergone by cancer cells, alter mechanical properties in the tumor microenvironment during cancer progression. Tumor mechanics conversely influence progression, and the identification of physical biomarkers promise improved diagnostic and prognostic power. Optical trap based active microrheology enables measurement of forces up to 0.5 mm within a sample, allowing interrogation of in vitro biomaterials, ex vivo tissue sections, and small organisms in vivo. We fabricated collagen I hydrogels exhibiting distinct structural properties by tuning polymerization temperature Tp, and measured their shear storage and loss moduli at frequencies 1-15k Hz at multiple amplitudes. Lower Tp gels, with larger pore size but thicker, longer fibers, were stiffer than higher Tp gels; decreasing strain increased loss moduli and decreased storage moduli at low frequencies. We subcutanously injected probes with metastatic murine melanoma cells into mice. The excised tumors displayed storage and loss moduli 40 Pa and 10 Pa at 1 Hz, increasing to 500 Pa and 1 kPa at 15 kHz, respectively.

  8. Embedded optical probes for simultaneous pressure and temperature measurement of materials in extreme conditions

    Science.gov (United States)

    Sandberg, R. L.; Rodriguez, G.; Gibson, L. L.; Dattelbaum, D. M.; Stevens, G. D.; Grover, M.; Lalone, B. M.; Udd, E.

    2014-05-01

    We present recent efforts at Los Alamos National Laboratory (LANL) to develop sensors for simultaneous, in situ pressure and temperature measurements under dynamic conditions by using an all-optical fiber-based approach. While similar tests have been done previously in deflagration-to-detonation tests (DDT), where pressure and temperature were measured to 82 kbar and 400°C simultaneously, here we demonstrate the use of embedded fiber grating sensors to obtain high temporal resolution, in situ pressure measurements in inert materials. We present two experimental demonstrations of pressure measurements: (1) under precise shock loading from a gas-gun driven plate impact and (2) under high explosive driven shock in a water filled vessel. The system capitalizes on existing telecom components and fast transient digitizing recording technology. It operates as a relatively inexpensive embedded probe (single-mode 1550 nm fiber-based Bragg grating) that provides a continuous fast pressure record during shock and/or detonation. By applying well-controlled shock wave pressure profiles to these inert materials, we study the dynamic pressure response of embedded fiber Bragg gratings to extract pressure amplitude of the shock wave and compare our results with particle velocity wave profiles measured simultaneously.

  9. Embedded Fiber Optic Probes to Measure Detonation Velocities Using the Photonic Doppler Velocimeter

    Energy Technology Data Exchange (ETDEWEB)

    Hare, D E; Holtkamp, D B; Strand, O T

    2010-03-02

    Detonation velocities for high explosives can be in the 7 to 8 km/s range. Previous work has shown that these velocities may be measured by inserting an optical fiber probe into the explosive assembly and recording the velocity time history using a Fabry-Perot velocimeter. The measured velocity using this method, however, is the actual velocity multiplied times the refractive index of the fiber core, which is on the order of 1.5. This means that the velocimeter diagnostic must be capable of measuring velocities as high as 12 km/s. Until recently, a velocity of 12 km/s was beyond the maximum velocity limit of a homodyne-based velocimeter. The limiting component in a homodyne system is usually the digitizer. Recently, however, digitizers have come on the market with 20 GHz bandwidth and 50 GS/s sample rate. Such a digitizer coupled with high bandwidth detectors now have the total bandwidth required to make velocity measurements in the 12 km/s range. This paper describes measurements made of detonation velocities using a high bandwidth homodyne system.

  10. Generating Entanglement between Atomic Spins with Low-Noise Probing of an Optical Cavity

    CERN Document Server

    Cox, Kevin C; Greve, Graham P; Thompson, James K

    2015-01-01

    Atomic projection noise limits the ultimate precision of all atomic sensors, including clocks, inertial sensors, magnetometers, etc. The independent quantum collapse of $N$ atoms into a definite state (for example spin up or down) leads to an uncertainty $\\Delta \\theta_{SQL}=1/\\sqrt{N}$ in the estimate of the quantum phase accumulated during a Ramsey sequence or its many generalizations. This phase uncertainty is referred to as the standard quantum limit. Creating quantum entanglement between the $N$ atoms can allow the atoms to partially cancel each other's quantum noise, leading to reduced noise in the phase estimate below the standard quantum limit. Recent experiments have demonstrated up to $10$~dB of phase noise reduction relative to the SQL by making collective spin measurements. This is achieved by trapping laser-cooled Rb atoms in an optical cavity and precisely measuring the shift of the cavity resonance frequency by an amount that depends on the number of atoms in spin up. Detecting the probe light ...

  11. Biconically Tapered Fiber Optic Probes for Rapid Label-Free Immunoassays

    Directory of Open Access Journals (Sweden)

    John Miller

    2015-04-01

    Full Text Available We report use of U-shaped biconically tapered optical fibers (BTOF as probes for label-free immunoassays. The tapered regions of the sensors were functionalized by immobilization of immunoglobulin-G (Ig-G and tested for detection of anti-IgG at concentrations of 50 ng/mL to 50 µg/mL. Antibody-antigen reaction creates a biological nanolayer modifying the waveguide structure leading to a change in the sensor signal, which allows real-time monitoring. The kinetics of the antibody (mouse Ig-G-antigen (rabbit anti-mouse IgG reactions was studied. Hydrofluoric acid treatment makes the sensitive region thinner to enhance sensitivity, which we confirmed by experiments and simulations. The limit of detection for the sensor was estimated to be less than 50 ng/mL. Utilization of the rate of the sensor peak shift within the first few minutes of the antibody-antigen reaction is proposed as a rapid protein detection method.

  12. Sapphire ball lensed fiber probe for common-path optical coherence tomography in ocular imaging and sensing

    Science.gov (United States)

    Zhao, Mingtao; Huang, Yong; Kang, Jin U.

    2013-03-01

    We describe a novel common-path optical coherence tomography (CP-OCT) fiber probe design using a sapphire ball lens for cross-sectional imaging and sensing in retina vitrectomy surgery. Single mode Gaussian beam (TEM00) simulation was used to optimize lateral resolution and working distance (WD) of the common-path probe. A theoretical sensitivity model for CP-OCT was prosed to assess its optimal performance based an unbalanced photodetector configuration. Two probe designs with working distances (WD) 415μm and 1221μm and lateral resolution 11μm and 18μm, respectively were implemented with sensitivity up to 88dB. The designs are also fully compatible with conventional Michelson interferometer based OCT configurations. The reference plane of the probe, located at the distal beam exit interface of the single mode fiber (SMF), was encased within a 25-gauge hypodermic needle by the sapphire ball lens facilitates its applications in bloody and harsh environments. The performances of the fiber probe with 11μm of lateral resolution and 19μm of axial resolution were demonstrated by cross-sectional imaging of a cow cornea and retina in vitro with a 1310nm swept source OCT system. This probe was also attached to a piezoelectric motor for active compensation of physiological tremor for handheld retinal surgical tools.

  13. STUDY OF A NEW POROUS PLASTIC OPTICAL FIBER PROBE BASED ON MOLECULAR LUMINESCENCE%基于分子发光的新型多孔塑料光纤传感探头的研究

    Institute of Scientific and Technical Information of China (English)

    谢增鸿; 郭良洽; 林旭聪; 陈国南

    2003-01-01

    A new porous plastic optical fiber probe was synthesized and proposed for preparation of optical chemical sensor. The basic principle,fabrication and characteristics of the porous plastic optical fiber probe are described in detail. The polymer fiber was made from the stock mixture of functional monomer,cross-linking reagent,pore-forming reagent and indicator. And it behaves great advantages as an optical fiber probe. This new porous plastic optical fiber probe has been used for preparing some optical chemical sensors, and these probes have been used for determination of halides, mercury, ammonia, oxygen and pH.

  14. Isoquinoline-based lanthanide complexes: bright NIR optical probes and efficient MRI agents.

    Science.gov (United States)

    Caillé, Fabien; Bonnet, Célia S; Buron, Frédéric; Villette, Sandrine; Helm, Lothar; Petoud, Stéphane; Suzenet, Franck; Tóth, Eva

    2012-02-20

    In the objective of developing ligands that simultaneously satisfy the requirements for MRI contrast agents and near-infrared emitting optical probes that are suitable for imaging, three isoquinoline-based polyaminocarboxylate ligands, L1, L2 and L3, have been synthesized and the corresponding Gd(3+), Nd(3+) and Yb(3+) complexes investigated. The specific challenge of the present work was to create NIR emitting agents which (i) have excitation wavelengths compatible with biological applications and (ii) are able to emit a sufficient number of photons to ensure sensitive NIR detection for microscopic imaging. Here we report the first observation of a NIR signal arising from a Ln(3+) complex in aqueous solution in a microscopy setup. The lanthanide complexes have high thermodynamic stability (log K(LnL) =17.7-18.7) and good selectivity for lanthanide ions versus the endogenous cations Zn(2+), Cu(2+), and Ca(2+) thus preventing transmetalation. A variable temperature and pressure (17)O NMR study combined with nuclear magnetic relaxation dispersion measurements yielded the microscopic parameters characterizing water exchange and rotation. Bishydration of the lanthanide cation in the complexes, an important advantage to obtain high relaxivity for the Gd(3+) chelates, has been demonstrated by (17)O chemical shifts for the Gd(3+) complexes and by luminescence lifetime measurements for the Yb(3+) analogues. The water exchange on the three Gd(3+) complexes is considerably faster (k(ex)(298) = (13.9-15.4) × 10(6) s(-1)) than on commercial Gd(3+)-based contrast agents and proceeds via a dissociative mechanism, as evidenced by the large positive activation volumes for GdL1 and GdL2 (+10.3 ± 0.9 and +10.6 ± 0.9 cm(3) mol(-1), respectively). The relaxivity of GdL1 is doubled at 40 MHz and 298 K in fetal bovine serum (r(1) = 16.1 vs 8.5 mM(-1) s(-1) in HEPES buffer), due to hydrophobic interactions between the chelate and serum proteins. The isoquinoline core allows for the

  15. Optical properties of an inhomogeneously broadened multilevel V-system in the weak and strong probe regimes

    CERN Document Server

    Kaur, Paramjit; Wasan, Ajay

    2015-01-01

    We present a theoretical model, using density matrix approach, to study the effect of weak as well as strong probe field on the optical properties of an inhomogeneously broadened multilevel V-system of the $^{87}$Rb D2 line. We consider the case of stationary as well as moving atoms and perform thermal averaging at room temperature. The presence of multiple excited states results in asymmetric absorption and dispersion profiles. In the weak probe regime, we observe the partial transparency window due to the constructive interference occurs between transition pathways at the line center. In a room temperature vapour, we obtain an increased linewidth of the transparency window and steep positive dispersion. For a strong probe regime, the transparency window with normal dispersion switches to enhanced absorption with anomalous dispersion at the line center. Here, we show how the electromagnetically induced transparency (EIT) depends on the polarizations of the applied fields. We also discuss the transient behavi...

  16. Four-probe scanning tunnelling microscope with atomic resolution for electrical and electro-optical property measurements of nanosystems

    Institute of Scientific and Technical Information of China (English)

    Lin Xiao; He Xiao-Bo; Lu Jun-Ling; Gao Li; Huan Qing; Shi Dong-Xia; Gao Hong-Jun

    2005-01-01

    We demonstrate a special four-probe scanning tunnelling microscope (STM) system in ultrahigh vacuum (UHV),which can provide coarse positioning for every probe independently with the help of scanning electron microscope (SEM)and fine positioning down to nanometre using the STM technology. The system allows conductivity measurement by means of a four-point probe method, which can draw out more accurate electron transport characteristics in nanostructures, and provides easy manipulation of low dimension materials. All measurements can be performed in variable temperature (from 30K to 500K), magnetic field (from 0 to 0.1T), and different gas environments. Simultaneously, the cathodoluminescence (CL) spectrum can be achieved through an optical subsystem. Test measurements using some nanowire samples show that this system is a powerful tool in exploring electron transport characteristics and spectra in nanoscale physics.

  17. Heterodyne pump-probe and four-wave mixing in semiconductor optical amplifiers using balanced lock-in detection

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, Wolfgang; Mørk, Jesper;

    1999-01-01

    We demonstrate a new detection scheme for pump-probe and four-wave mixing heterodyne experiments, using balanced detection and a dual-phase lock-in for spectral filtering. The technique allows the use of low repetition-rate laser systems, as is demonstrated on an InGaAsP/InP bulk optical amplifier...... at 1.53 mym. Ultrafast pump-induced changes in the amplitude and phase of the transmitted probe signal are simultaneously measured, going from small to large signal changes and with no need of an absolute phase calibration, showing the versatility and the sensitivity of this detection scheme....... The results for small perturbations are consistent with previous pump-probe experiments reported in literature. Time-resolved four-wave mixing in the absorption regime of the device is measured, and compared with numerical simulations, indicating a 100 fs dephasing time....

  18. Pump and probe damage testing for investigation of transient material modifications associated with laser damage in optical materials

    Energy Technology Data Exchange (ETDEWEB)

    Negres, R A; Feit, M D; DeMange, P; Bude, J D; Demos, S G

    2007-10-18

    Laser-induced breakdown in the bulk of transparent dielectric materials is associated with the generation of extreme localized conditions of temperatures and pressures. In this work, we perform pump and probe damage testing experiments to investigate the evolution of transient absorption by the host material arising from modifications following confined laser energy deposition in fused silica and DKDP materials. Specifically, we measure the size of the damage sites observed in the region of spatial overlap between the pump and probe pulses versus probe time delay and energy. Results of this proof-of-principle experimental work confirm that material modifications under extreme conditions created during a damage event include transient optical absorption. In addition, we found that the relaxation times of the induced absorption are very distinct for DKDP and SiO{sub 2} even under identical excitation conditions, on the order of 100 ns and 100 {micro}s, respectively.

  19. An optical fiber taper fluorescent probe for detection of nitro-explosives based on tetraphenylethylene with aggregation-induced emission

    Science.gov (United States)

    Liu, Fukun; Cui, Minxin; Ma, Jiajun; Zou, Gang; Zhang, Qijin

    2017-07-01

    In this work, we report a novel optical fiber taper fluorescent probe for detection of nitro-explosives. The probe was fabricated by an in-situ photo-plating through evanescent wave and transmitted light initiated thiol-ene ;click; reaction, from which a cross-linked fluorescence porous polymer film was covalently bonded on the surface of the fiber taper. The film exhibits well-organized porous structure due to the presence of polyhedral oligomeric vinylsilsesquioxane moieties, and simultaneously displays strong fluorescence from tetraphenylethylene with aggregation-induced emission property. These two characters make the probe show a remarkable sensitivity, anti-photo-bleaching and a repeatability in detection of TNT and DNT vapors by fluorescence quenching. In addition, the detection is not interfered in the presence of other volatile organic gases.

  20. A comparison measurement of nonlinear ultrasonic waves in tubes by a microphone and by an optical interferometric probe.

    Science.gov (United States)

    Slegrová, Zuzana; Bálek, Rudolf

    2005-03-01

    This paper deals with the analysis of ultrasonic fields inside waveguides generated by ultrasonic waves of high amplitude. These waves behave nonlinearly, so it is not possible to use standard linear equations to describe their behaviour. Therefore, we started with an experimental determination of the acoustic pressure of air in glass tubes. We chose two methods of measurement--by a microphone and by an optical interferometric probe. The conventional method by a microphone creates numerous problems, which can be avoided by using an optical method, a heterodyne laser interferometer.

  1. Spectrum of turbulent-boundary-layer fluctuation pressure and response of a polyvinylidence fluoride hydrophone

    Institute of Scientific and Technical Information of China (English)

    GE Huiliang; HE Zuoyong; BAO Xuemei

    2001-01-01

    The point power spectrum density and the wavenumber frequency spectrum density of turbulent-boundary-layer fluctuation pressure were measured in water-tunnel by use of a φ8 mm hydrophone and a 20-element array, respectively. The non-dimensional representation of measured point power spectrum coincides with the measured results by Bull M. K. et. al. in wind tunnel. The convection peak can be seen clearly in the measured wavenumber frequencyspectrum and the convection velocity can be calculated from the location of the convection peak.The response spectrum of a polyvinylidence fluoride (PVDF) hydrophone, which receiving area is 100 mm × 60 mm, was also measured. By comparing it with the response spectrum of the φ8 mm hydrophone, it is shown that the PVDF hyrdophone has a strong wavenumber filtering effect on turbulent-boundary-layer pressure fluctuation.

  2. Design and characterization of a novel multimodal fiber-optic probe and spectroscopy system for skin cancer applications

    Science.gov (United States)

    Sharma, Manu; Marple, Eric; Reichenberg, Jason; Tunnell, James W.

    2014-08-01

    The design and characterization of an instrument combining Raman, fluorescence, and reflectance spectroscopic modalities is presented. Instrument development has targeted skin cancer applications as a novel fiber-optic probe has been specially designed to interrogate cutaneous lesions. The instrument is modular and both its software and hardware components are described in depth. Characterization of the fiber-optic probe is also presented, which details the probe's ability to measure diagnostically important parameters such as intrinsic fluorescence and absorption and reduced scattering coefficients along with critical performance metrics such as high Raman signal-to-noise ratios at clinically practical exposure times. Validation results using liquid phantoms show that the probe and system can extract absorption and scattering coefficients with less than 10% error. As the goal is to use the instrument for the clinical early detection of skin cancer, preliminary clinical data are also presented, which indicates our system's ability to measure physiological quantities such as relative collagen and nicotinamide adenine dinucleotide concentration, oxygen saturation, blood volume fraction, and mean vessel diameter.

  3. Novel electronic ferroelectricity in an organic charge-order insulator investigated with terahertz-pump optical-probe spectroscopy

    Science.gov (United States)

    Yamakawa, H.; Miyamoto, T.; Morimoto, T.; Yada, H.; Kinoshita, Y.; Sotome, M.; Kida, N.; Yamamoto, K.; Iwano, K.; Matsumoto, Y.; Watanabe, S.; Shimoi, Y.; Suda, M.; Yamamoto, H. M.; Mori, H.; Okamoto, H.

    2016-02-01

    In electronic-type ferroelectrics, where dipole moments produced by the variations of electron configurations are aligned, the polarization is expected to be rapidly controlled by electric fields. Such a feature can be used for high-speed electric-switching and memory devices. Electronic-type ferroelectrics include charge degrees of freedom, so that they are sometimes conductive, complicating dielectric measurements. This makes difficult the exploration of electronic-type ferroelectrics and the understanding of their ferroelectric nature. Here, we show unambiguous evidence for electronic ferroelectricity in the charge-order (CO) phase of a prototypical ET-based molecular compound, α-(ET)2I3 (ET:bis(ethylenedithio)tetrathiafulvalene), using a terahertz pulse as an external electric field. Terahertz-pump second-harmonic-generation(SHG)-probe and optical-reflectivity-probe spectroscopy reveal that the ferroelectric polarization originates from intermolecular charge transfers and is inclined 27° from the horizontal CO stripe. These features are qualitatively reproduced by the density-functional-theory calculation. After sub-picosecond polarization modulation by terahertz fields, prominent oscillations appear in the reflectivity but not in the SHG-probe results, suggesting that the CO is coupled with molecular displacements, while the ferroelectricity is electronic in nature. The results presented here demonstrate that terahertz-pump optical-probe spectroscopy is a powerful tool not only for rapidly controlling polarizations, but also for clarifying the mechanisms of ferroelectricity.

  4. The backscatter cloud probe - a compact low-profile autonomous optical spectrometer

    Science.gov (United States)

    Beswick, K.; Baumgardner, D.; Gallagher, M.; Volz-Thomas, A.; Nedelec, P.; Wang, K.-Y.; Lance, S.

    2014-05-01

    A compact (500 cm3), lightweight (500 g), near-field, single particle backscattering optical spectrometer is described that mounts flush with the skin of an aircraft and measures the concentration and optical equivalent diameter of particles from 5 to 75 μm. The backscatter cloud probe (BCP) was designed as a real-time qualitative cloud detector primarily for data quality control of trace gas instruments developed for the climate monitoring instrument packages that are being installed on commercial passenger aircraft as part of the European Union In-Service Aircraft for a Global Observing System (IAGOS) program (http://www.iagos.org/). Subsequent evaluations of the BCP measurements on a number of research aircraft, however, have revealed it capable of delivering quantitative particle data products including size distributions, liquid-water content and other information on cloud properties. We demonstrate the instrument's capability for delivering useful long-term climatological, as well as aviation performance information, across a wide range of environmental conditions. The BCP has been evaluated by comparing its measurements with those from other cloud particle spectrometers on research aircraft and several BCPs are currently flying on commercial A340/A330 Airbus passenger airliners. The design and calibration of the BCP is described in this article, along with an evaluation of measurements made on the research and commercial aircraft. Preliminary results from more than 7000 h of airborne measurements by the BCP on two Airbus A340s operating on routine global traffic routes (one Lufthansa, the other China Airlines) show that more than 340 h of cloud data have been recorded at normal cruise altitudes (> 10 km) and more than 40% of the > 1200 flights were through clouds at some point between takeoff and landing. These data are a valuable contribution to databases of cloud properties, including sub-visible cirrus, in the upper troposphere and useful for validating

  5. Optical Characterization of a Hollow Fiber Raman Probe toward Non-Invasive Measurements of Living Tissues

    Science.gov (United States)

    Mitsuoka, Hiroki; Morita, Shin-ichi; Suzuki, Toshiaki; Matsuura, Yuji; Katsumoto, Yukiteru; Sato, Hidetoshi

    2009-02-01

    The use of a hollow fiber as a Raman probe, which gives strong advantage of a free link in space, was confirmed to be a versatile and standard analytical method, since Raman data obtained through a hollow fiber probe assures a sufficient link to conventional Raman data. In this paper, we confirmed that a Raman spectrum given by the hollow fiber probe becomes identical to a Raman spectrum measured by a conventional approach, if one is multiplied by an optimized coefficient. In addition, Raman signal intensity changes were related to various types of curved geometries of the probe. The Raman signal intensity value at a curved geometry of the probe, which is one of the most frequently used positions, became 0.35 compared to the value at the standard position of the probe (straight lined).

  6. Detection and characterization of atherosclerotic plaques by Raman probe spectroscopy and optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Matthäus, Christian; Dochow, Sebastian; Egodage, Kokila D.; Schie, Iwan; Romeike, Bernd F.; Brehm, Bernhard R.; Popp, Jürgen

    2017-02-01

    Visualization and characterization of inner arterial plaque depositions is of vital diagnostic interest. Established intravascular imaging techniques provide valuable morphological information, but cannot deliver information about the chemical composition of individual plaques. Probe based Raman spectroscopy offers the possibility for a biochemical characterization of atherosclerotic plaque formations during an intravascular intervention. From post mortem studies it is well known that the severity of a plaque and its stability are strongly correlated with its biochemical composition. Especially the identification of vulnerable plaques remains one of the most important and challenging aspects in cardiology. Thus, specific information about the composition of a plaque would greatly improve the risk assessment and management. Furthermore, knowledge about the composition can offer new therapeutic and medication strategies. Plaque calcifications as well as major lipid components such as cholesterol, cholesterol esters and triglycerides can be spectroscopically easily differentiated. Intravascular optical coherence tomography (OCT) is currently a prominent catheter based imaging technique for the localization and visualization of atherosclerotic plaque depositions. The high resolution of OCT with 10 to 15 µm allows for very detailed characterization of morphological features such as different plaque formations, thin fibrous caps and accurate measurements of lesion lengths. In combination with OCT imaging the obtained spectral information can provide substantial information supporting on on-site diagnosis of various plaque types and therefor an improved risk assessment. The potential and feasibility of combining OCT with Raman spectroscopy is demonstrated on excised plaque samples, as well as under in vivo conditions. Acknowledgements: Financial support from the Carl Zeiss Foundation is greatly acknowledged.

  7. Detection of Helicobacter Pylori Genome with an Optical Biosensor Based on Hybridization of Urease Gene with a Gold Nanoparticles-Labeled Probe

    Science.gov (United States)

    Shahrashoob, M.; Mohsenifar, A.; Tabatabaei, M.; Rahmani-Cherati, T.; Mobaraki, M.; Mota, A.; Shojaei, T. R.

    2016-05-01

    A novel optics-based nanobiosensor for sensitive determination of the Helicobacter pylori genome using a gold nanoparticles (AuNPs)-labeled probe is reported. Two specific thiol-modified capture and signal probes were designed based on a single-stranded complementary DNA (cDNA) region of the urease gene. The capture probe was immobilized on AuNPs, which were previously immobilized on an APTES-activated glass, and the signal probe was conjugated to different AuNPs as well. The presence of the cDNA in the reaction mixture led to the hybridization of the AuNPs-labeled capture probe and the signal probe with the cDNA, and consequently the optical density of the reaction mixture (AuNPs) was reduced proportionally to the cDNA concentration. The limit of detection was measured at 0.5 nM.

  8. Optical signatures of low spin Fe3+: a new probe for the spin state of bridgmanite and post-perovskite

    CERN Document Server

    Lobanov, Sergey S; Lin, Jung-Fu; Yoshino, Takashi; Goncharov, Alexander F

    2016-01-01

    Iron spin transition directly affects properties of lower mantle minerals and can thus alter geophysical and geochemical characteristics of the deep Earth. While the spin transition in ferropericlase has been vigorously established at P ~ 60 GPa and 300 K, experimental evidence for spin transitions in other rock-forming minerals, such as bridgmanite and post-perovskite, remains controversial. Multiple valence, spin, and coordination states of iron in bridgmanite and post-perovskite are difficult to resolve with conventional spin-probing techniques. Optical spectroscopy, on the other hand, is sensitive to high/low spin ferrous/ferric iron at different sites; thus, it can be a powerful probe for spin transitions. Here we establish the optical signature of low spin Fe3+O6, a plausible low spin unit in bridgmanite and post-perovskite, by optical absorption experiments in diamond anvil cells. We show that the optical absorption of Fe3+O6 in NAL (new aluminous phase) is very sensitive to the iron spin state and rep...

  9. Dynamic Probing of Nanoparticle Stability In Vivo: A Liposomal Model Assessed Using In Situ Microdialysis and Optical Imaging

    Directory of Open Access Journals (Sweden)

    Chien-Chung Jeng

    2011-01-01

    Full Text Available Nanoparticle-mediated drug delivery and controlled release has been a vigorous research area in contemporary nanomedicine. The in vivo stability of nanoparticle delivered on site is a prerequisite for the design of drug-controlled release by any means. In this study, the first methodology comprised of microdialysis and optical imaging to assess the liposome stability in vivo is reported. Macroscopically, we demonstrated the DPPG liposomes with negative surface charge fast accumulated in the rat liver upon their i.v. administration using optical imaging. Microscopically, the concurrent analysis of fluorescent molecules leaching from the liposomes, in situ sampled using microdialysis probe, provides the dynamic information of stability of DPPG liposomes locus in quo. The current combination of in situ microdialysis and optical imaging possesses a great potential for use as a platform technology to evaluate the nanoparticle stability and the bioavailability of drug payload released on targeted site in vivo.

  10. Novel Fiber Optic Sensor Probe with a Pair of Highly Reflected Connectors and a Vessel of Water Absorption Material for Water Leak Detection

    Directory of Open Access Journals (Sweden)

    Tae-Sik Cho

    2012-08-01

    Full Text Available The use of a fiber optic quasi-distributed sensing technique for detecting the location and severity of water leakage is suggested. A novel fiber optic sensor probe is devised with a vessel of water absorption material called as water combination soil (WCS located between two highly reflected connectors: one is a reference connector and the other is a sensing connector. In this study, the sensing output is calculated from the reflected light signals of the two connectors. The first reflected light signal is a reference and the second is a sensing signal which is attenuated by the optical fiber bending loss due to the WCS expansion absorbing water. Also, the bending loss of each sensor probe is determined by referring to the total number of sensor probes and the total power budget of an entire system. We have investigated several probe characteristics to show the design feasibility of the novel fiber sensor probe. The effects of vessel sizes of the probes on the water detection sensitivity are studied. The largest vessel probe provides the highest sensitivity of 0.267 dB/mL, while the smallest shows relatively low sensitivity of 0.067 dB/mL, and unstable response. The sensor probe with a high output value provides a high sensitivity with various detection levels while the number of total installable sensor probes decreases.

  11. Dynamic PET and Optical Imaging and Compartment Modeling using a Dual-labeled Cyclic RGD Peptide Probe

    Directory of Open Access Journals (Sweden)

    Lei Zhu, Ning Guo, Quanzheng Li, Ying Ma, Orit Jacboson, Seulki Lee, Hak Soo Choi, James R. Mansfield, Gang Niu, Xiaoyuan Chen

    2012-01-01

    Full Text Available Purpose: The aim of this study is to determine if dynamic optical imaging could provide comparable kinetic parameters to that of dynamic PET imaging by a near-infrared dye/64Cu dual-labeled cyclic RGD peptide.Methods: The integrin αvβ3 binding RGD peptide was conjugated with a macrocyclic chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA for copper labeling and PET imaging and a near-infrared dye ZW-1 for optical imaging. The in vitro biological activity of RGD-C(DOTA-ZW-1 was characterized by cell staining and receptor binding assay. Sixty-min dynamic PET and optical imaging were acquired on a MDA-MB-435 tumor model. Singular value decomposition (SVD method was applied to compute the dynamic optical signal from the two-dimensional optical projection images. Compartment models were used to quantitatively analyze and compare the dynamic optical and PET data.Results: The dual-labeled probe 64Cu-RGD-C(DOTA-ZW-1 showed integrin specific binding in vitro and in vivo. The binding potential (Bp derived from dynamic optical imaging (1.762 ± 0.020 is comparable to that from dynamic PET (1.752 ± 0.026.Conclusion: The signal un-mixing process using SVD improved the accuracy of kinetic modeling of 2D dynamic optical data. Our results demonstrate that 2D dynamic optical imaging with SVD analysis could achieve comparable quantitative results as dynamic PET imaging in preclinical xenograft models.

  12. Optical Probing of CO2 Laser-Plasma Interactions at Near Critical Density

    Science.gov (United States)

    Gong, Chao

    by a factor of 100 ( nc ≈1 x 1019cm -3). Therefore overdense CO2 laser plasma is transparent for a fast optical probe which opens a unique opportunity to study the physics of laser hole boring in the temporal and spatial domain simultaneously. This thesis reports the first direct measurements of the laser hole boring velocity in an overdense plasma using a four-frame picosecond green pulse interferometry. The plasma was created by tunnel ionization of a plume of He gas from a gas jet using a train of 3ps long CO2 laser pulses. For probing the plasma, a ˜2ps frequency-doubled (532nm) Nd:Glass laser pulse is used in a four-frame interferometry scheme. Spatio-temporal dynamics of hole boring in CO2 laser-plasma interaction at Ilambda 2 ≤2x1018 Wmum2/cm 2 are studied with a ˜15microm spatial and better than 2ps time resolutions. Experimental measurements indicate the hole boring process is determined by a balance between the radiation pressure PL and thermal pressure Pth. As a result of this competition, nuhb increases during the risetime of the laser pulse where PL > Pth but decreases with a larger slope rate on the falling edge. This is because the plasma electrons once heated cool slowly and Pth diminishes the efficacy of PL even faster.

  13. Measurement of axial neutral density profiles in a microwave discharge ion thruster by laser absorption spectroscopy with optical fiber probes.

    Science.gov (United States)

    Tsukizaki, Ryudo; Koizumi, Hiroyuki; Nishiyama, Kazutaka; Kuninaka, Hitoshi

    2011-12-01

    In order to reveal the physical processes taking place within the "μ10" microwave discharge ion thruster, internal plasma diagnosis is indispensable. However, the ability of metallic probes to access microwave plasmas biased at a high voltage is limited from the standpoints of the disturbance created in the electric field and electrical isolation. In this study, the axial density profiles of excited neutral xenon were successfully measured under ion beam acceleration by using a novel laser absorption spectroscopy system. The target of the measurement was metastable Xe I 5p(5)((2)P(0) (3/2))6s[3/2](0) (2) which absorbed a wavelength of 823.16 nm. Signals from laser absorption spectroscopy that swept a single-mode optical fiber probe along the line of sight were differentiated and converted into axial number densities of the metastable neutral particles in the plasma source. These measurements revealed a 10(18) m(-3) order of metastable neutral particles situated in the waveguide, which caused two different modes during the operation of the μ10 thruster. This paper reports a novel spectroscopic measurement system with axial resolution for microwave plasma sources utilizing optical fiber probes.

  14. Characterization of RF He-N2/Ar mixture plasma via Langmuir probe and optical emission spectroscopy techniques

    Science.gov (United States)

    Younus, Maria; Rehman, N. U.; Shafiq, M.; Hussain, S. S.; Zakaullah, M.; Zaka-ul-Islam, M.

    2016-08-01

    A Magnetic Pole Enhanced inductively coupled RF H e - N 2 / A r plasma is characterized using a Langmuir probe and optical emission spectroscopy (OES) techniques. The effect of helium mixing on electron density ( n e ) and temperature ( T e ) , electron energy probability functions (EEPFs), [ N ] atomic density, and N 2 dissociation is investigated. A Langmuir probe and a zero slope method based on trace rare gas-optical emission spectroscopy (TRG-OES) are employed to measure the electron temperature. It is noted that the electron temperature shows an increasing trend for both methods. However, the temperature measured by a zero slope method T e ( Z . S ) approaches the temperature measured by a Langmuir probe; T e ( L . P ) at 56% and above helium concentration in the discharge. "Advance actinometry" is employed to monitor the variation in [ N ] atomic density with helium concentration and gas pressure. It is noted that [ N ] atomic density increases at 56% and above helium in the discharge, which is consistent with the trend of electron temperature and EEPFs. A drastic enhancement in N 2 dissociation fraction D 1 determined by "advance actinometry" is noted at 56% and above helium concentration in the mixture due to modifications in different population and depopulation mechanisms. However, it is also noted that the dissociation fraction D 2 determined by intensity ratio method increases linearly with helium addition.

  15. Determination of Propranolol Hydrochloride in Pharmaceutical Preparations Using Near Infrared Spectrometry with Fiber Optic Probe and Multivariate Calibration Methods

    Directory of Open Access Journals (Sweden)

    Jucelino Medeiros Marques Junior

    2015-01-01

    Full Text Available A method for determination of propranolol hydrochloride in pharmaceutical preparation using near infrared spectrometry with fiber optic probe (FTNIR/PROBE and combined with chemometric methods was developed. Calibration models were developed using two variable selection models: interval partial least squares (iPLS and synergy interval partial least squares (siPLS. The treatments based on the mean centered data and multiplicative scatter correction (MSC were selected for models construction. A root mean square error of prediction (RMSEP of 8.2 mg g−1 was achieved using siPLS (s2i20PLS algorithm with spectra divided into 20 intervals and combination of 2 intervals (8501 to 8801 and 5201 to 5501 cm−1. Results obtained by the proposed method were compared with those using the pharmacopoeia reference method and significant difference was not observed. Therefore, proposed method allowed a fast, precise, and accurate determination of propranolol hydrochloride in pharmaceutical preparations. Furthermore, it is possible to carry out on-line analysis of this active principle in pharmaceutical formulations with use of fiber optic probe.

  16. Working-point control technique for the homodyne interferometry in hydrophone calibration

    Science.gov (United States)

    Yang, Ping; Xing, Guangzhen

    2015-02-01

    The stabilization of a homodyne type Michelson interferometer for calibrating the high frequency hydrophone is presented in this article. For the detection of the ultrasonic field, a 5 um thickness pellicle was inserted in water moving in sympathy with the ultrasonic wave. To ensure high signal to noise ratio at high frequencies, a 5 MHz focusing transducer was driven by high voltage and harmonics of the shocked ultrasonic field could be activated. Nevertheless, the homodyne interferometer suffered from the drawback of signal fading caused by the low frequency noise in environment, including acoustic noise and water surface agitation. Direct Current Phase Tracking was utilized to maintain the quadrature working point for the interferometer. Most of environmental noises could be effectively compensated while stabilization was maintained. A piezoelectric actuator supporting the reference mirror was utilized as the stabilizing element whose output was frequency independent over the low frequency disturbances, usually below 200 Hz. The ultrasonic signal fading caused by environmental disturbances could be solved while the negative electric feedback loop was operating. The displacement and voltage output of the hydrophone under test were then processed by DFT to derive the fundamental and harmonic components. Under plane wave conditions, the ultrasonic pressure could be derived by the detected displacement with a stabilized homodyne interferometer, and the hydrophone could then be calibrated. Measurement results indicated that the hydrophone calibration system based on the active stabilization of homodyne interferometry was sound in theory and feasible in practice.

  17. Development of a Novel Fiber Optic Sensor Combined with a Fluorescence Turn-on Probe for Cu (II Detection

    Directory of Open Access Journals (Sweden)

    Ma J.

    2013-04-01

    Full Text Available Existing staining-based methodology for the detection of metal ions is not well suited for real-time or in situ use. This is a significant problem, given that these ions can have a considerable impact on both human health and the environment. Thus, there is growing interest and need for simple, rapid and in-situ monitoring techniques for the purpose of detecting various target analytes (e.g. heavy metals, which is of a significant importance in many fields ranging from environmental monitoring to the study of intracellular processes. Among various sensors developed, optical fiber-optic sensors (FOS, based on fluorescence, are one class of sensors that address this goal [1]. Optical fibers are ideal for environmental sensing applications because of their ability to transmit optical signals to and from the sensing region without the use of free-space optics. In this work, we present, for the first time, a simple FOS incorporating novel fluorescence turn-on mechanism [2] that could detect Cu (II as low as 10−4 M. Traditionally, fluorescence quenching or “turn-off” was used to detect Cu (II [3]. In recent years, fluorescence “turn-on” emerges as a preferable tool. The developed fiber-optic sensor has two fiber leads and one probe head. One fiber lead includes 6 fibers for He-Ne laser excitation light delivery (e-fibers. Another fiber lead has one receiving fiber (r-fiber connected to an Ocean Optics QE65000 scientific grade spectrometer, which is interrogated by a computer via USB connection. The SpectroSuite software is used to observe and to record all spectra. The probe head combines all fibers together to form a coaxial structure with the r-fiber placed in the center. The key component in the proposed fluorescent sensing system is a probe prepared by binding a receptor containing a zwitterionic chromophore (M1, through noncovalent interactions, to the fluorescent polymer (P1 resulting in quenching its emission. The sensing mechanism

  18. Study of polarization properties of fiber-optics probes with use of a binary phase plate.

    Science.gov (United States)

    Alferov, S V; Khonina, S N; Karpeev, S V

    2014-04-01

    We conduct a theoretical and experimental study of the distribution of the electric field components in the sharp focal domain when rotating a zone plate with a π-phase jump placed in the focused beam. Comparing the theoretical and experimental results for several kinds of near-field probes, an analysis of the polarization sensitivity of different types of metal-coated aperture probes is conducted. It is demonstrated that with increasing diameter of the non-metal-coated tip part there occurs an essential redistribution of sensitivity in favor of the transverse electric field components and an increase of the probe's energy throughput.

  19. Numerical analysis of transmission efficiency for parabolic optical fiber nano-probe.

    Science.gov (United States)

    Zhu, Wei; Shi, Tielin; Tang, Zirong; Gong, Bo; Liao, Guanglan; Liu, Shiyuan

    2013-11-18

    Theoretical calculations are performed for the transmission efficiencies of parabolic nano-probes with different shapes, based on the finite element method. It shows that the transmittance will fluctuate dramatically with the variation of either wavelength or probe shape, and the efficiency could be rather high even at long wavelengths. Subsequently, we thoroughly investigate this phenomenon and find that these fluctuations are due to the joint effect of light propagating modes and surface plasmon polaritons modes. It indicates that high transmittance can be achieved with the selection of appropriate wavelength and probe structure.

  20. Hydrophone localization for the newly installed CTBTO station HA04 using noise from the installation vessel

    Science.gov (United States)

    Nielsen, Peter; Haralabus, Georgios; Stanley, Jerry; Zampolli, Mario; Grenard, Patrick; Brown, David; Le Bras, Ronan; Amir, Menachem; Slava, Bereza; Bittner, Paulina; Gore, Jane; Wang, Haijun

    2017-04-01

    During December 2016, the cabled hydroacoustic station HA04 was installed close to the Crozet Islands, France, in the southern Indian Ocean as part of the Comprehensive Nuclear-Test-Ban Treaty Organization's (CTBTO) International Monitoring System (IMS) designed to detect nuclear explosions worldwide. The HA04 station consists of two triplets of cabled to shore hydrophones deployed north and south of Crozet. Each triplet forms a two kilometre triangular configuration positioned in the Sound Fixing and Ranging channel for optimum performance. The water depth is approximately 1200 m with the hydrophones connected to a riser cable of approximately 700 m in length. The deployment was conducted from a cable vessel utilising high precision global and dynamic positioning system to position the sensors as close as possible to the planned locations. Although high confidence in the sensor locations was achieved during the vessel operation, the locations were verified by independent means in order to refine sensor locations, optimize station performance, and to ensure that the deployment was within the tolerance of the terms of reference for the deployment. The alternative estimate of the individual sensor locations was formulated as a global optimization problem with 10 unknown parameters, i.e., latitude, longitude and depth for each sensor within a station and an effective sound speed value in water. The objective function was defined as a least-mean-square type error function between modelled and measured arrival times between pairs of hydrophones. The arrival times were obtained by cross-correlating radiated noise from the surface vessel deploying the sensors while performing a dedicated known track for the purpose of the hydrophone localization. Results from the hydrophone localization estimation are presented and compared to the planned positions together with uncertainty estimates caused by independent modelling and measurement errors.

  1. Design and development of PVDF-based MEMS hydrophone and accelerometer

    Science.gov (United States)

    Zhu, Bei

    It is always desirable to fabricate low-cost, highly sensitive and miniaturized sensors for various applications. In this thesis, the design and processing of PVDF-based MEMS hydrophones and accelerometers have been investigated. The basic structure of the hydrophone was fabricated on a silicon wafer using standard NMOS process technology. A MOSFET with extended gate electrode was designed as the interface circuit to a sensing material, which is a piezoelectric polymer, polyvinylidene difluoride (PVDF). Acoustic impedance possessed by this piezoelectric material provides a reasonable match to that of water, which makes it very attractive for underwater applications. The electrical signal generated by the PVDF film was directly coupled to the gate of the MOSFET. In order to minimize the parasitic capacitance underneath the PVDF film and hence improve the device sensitivity, a thick photoresist, SU-8, was first employed as the dielectric layer under the extended gate electrode. For underwater operation, the hydrophone was encapsulated by a waterproof Rho-C rubber. However, it was found that the rubber induced the degradation of the MOSFET. To improve the reliability of the hydrophone, the active device was passivated by a silicon nitride layer, which is a good barrier material to most mobile ions and solvents. The device after passivation also shows a lower noise level. A theoretical model was developed to predict the sensitivity of the hydrophone. A reasonable agreement between the theoretical and experimental results was obtained. MEMS accelerometers based on the PVDF-MOSFET structure by attaching a seismic mass on top of the PVDF film were also fabricated. The accelerometer was calibrated using a comparison method and an average sensitivity of 0.28 mV/g was achieved. A dynamic model of the accelerometer was derived and the calculated results are in good agreement with the measured results.

  2. Detection and quantification of additives (urea, biuret and poultry litter) in alfalfas by NIR spectroscopy with fibre-optic probe.

    Science.gov (United States)

    González-Martín, Inmaculada; Hernández-Hierro, José Miguel

    2008-09-15

    The additives (urea, biuret and poultry litter) present in alfalfa, which contribute non-proteic nitrogen, were analysed using near infrared spectroscopy (NIRS) technology together with a remote reflectance fibre-optic probe. We used 75 samples of known alfalfa without additives and 75 samples with each of the additives, urea (0.01-10%), biuret (0.01-10%) and poultry litter (1-25%). Using the discriminant partial least squares (DPLS) algorithm, the presence or absence of the additives urea, biuret and poultry litter is classified and predicted with a high prediction rate of 96.9%, 100% and 100%, obtaining the equations of discrimination for each additive. The regression method employed for the quantification was modified partial least squares (MPLS). The equations were developed using the fibre-optic probe to determine the content of urea, biuret and poultry litter with multiple correlation coefficients (RSQ) and prediction corrected standard errors (SEP (C)) of 0.990, 0.28% for urea, 0.991, 0.29% for biuret and 0.925, 2.08% for poultry litter. The work permits the instantaneous and simultaneous prediction and determination of urea, biuret and poultry litter in alfalfas, applying the fibre-optic directly on the ground samples of alfalfa.

  3. Invited Article: SUBGLACIOR: An optical analyzer embedded in an Antarctic ice probe for exploring the past climate

    Energy Technology Data Exchange (ETDEWEB)

    Grilli, R.; Marrocco, N.; Desbois, T. [CNRS, LIPhy, F-38000 Grenoble (France); Guillerm, C. [DT INSU CNRS, Bât. IPEV BP 74, Technopole Brest Iroise, 29280 Plouzané (France); Triest, J. [CNRS, LGGE, F-38000 Grenoble (France); Kerstel, E.; Romanini, D. [CNRS, LIPhy, F-38000 Grenoble (France); Univ. Grenoble Alpes, LIPhy, F-38000 Grenoble (France)

    2014-11-15

    This article describes the advances made in the development of a specific optical spectrometer based on the Optical Feedback-Cavity Enhanced Absorption Spectroscopy technique for exploring past climate by probing the original composition of the atmosphere stored in the ice sheet of a glacier. Based on significant technological progresses and unconventional approaches, SUBGLACIOR will be a revolutionary tool for ice-core research: the optical spectrometer, directly embedded in the drilling probe, will provide in situ real-time measurements of deuterium isotopic variations (δ{sup 2}H ) and CH{sub 4} concentrations down to 3500 m of ice depth within a single Antarctic season. The instrument will provide simultaneous and real-time vertical profiles of these two key climate signatures in order to evaluate if a target site can offer ice cores as old as 1.5 million years by providing direct insight into past temperatures and climate cycles. The spectrometer has a noise equivalent absorption coefficient of 2.8 × 10{sup −10} cm{sup −1} Hz{sup −1/2}, corresponding to a detection limit of 0.2 ppbv for CH{sub 4} and a precision of 0.2‰ on the δ{sup 2}H of H{sub 2}O within 1 min acquisition time.

  4. Evaluation of probe lasers employed in optical diagnostics for phase transformation of thin films during excimer laser crystallization

    Science.gov (United States)

    Kuo, Chil-Chyuan

    2008-06-01

    The stability and reliability of probe laser is an important factor affecting the inspection of the phase transformation process of Si thin films during excimer laser crystallization using in-situ time-resolved optical measurements. The changes in 2D intensity profile, peak power density, and beam wander of the commonly used helium-neon (He-Ne) and diode laser are investigated experimentally. It is found that the peak power density of He-Ne laser is higher than that of diode laser, while the total power of He-Ne laser is lower than that of diode laser. Although the instability in the peak power density of He-Ne laser will increase with increasing the operation time, the beam stability of He-Ne laser is better than that of diode laser. For long-time operation (>24 h) of optical measurements, the diode laser is a good candidate of probe laser. Conversely, the diode laser is suitable for the short-time operation (<24 h) of optical measurements because the beam-wander is higher than that of He-Ne laser.

  5. Use of NIRS technology with a remote reflectance fibre-optic probe for predicting major components in cheese.

    Science.gov (United States)

    González-Martín, Inmaculada; González-Pérez, Claudio; Hernández-Hierro, José Miguel; González-Cabrera, José Miguel

    2008-04-15

    In the present work the potential of near infra-red spectroscopy technology (NIRS) together with the use of a remote reflectance fibre-optic probe for the analysis of fat, moisture, protein and chlorides contents of commercial cheeses elaborated with mixtures of cow's, ewe's and goat's milk and with different curing times was examined. The probe was applied directly, with no previous sample treatment. The regression method employed was modified partial least squares (MPLS). The equations developed for the cheese samples afforded fat, moisture, protein, and chloride contents in the range 13-52%, 10-62%, 20-30%, and 0.7-2.9%, respectively. The multiple correlation coefficients (RSQ) and prediction corrected standard errors (SEP (C)) obtained were respectively 0.97 and 0.995% for fat; 0.96% and 1.640% for moisture; 0.78% and 0.760% for protein, and 0.89% and 0.112% for chlorides.

  6. Performance limit of a multi-frequency probe based coherent optical time domain reflectometry caused by nonlinear effects

    Institute of Scientific and Technical Information of China (English)

    Lidong Lü; Yuejiang Song; Fan Zhu; Xuping Zhang

    2012-01-01

    The nonlinear effects that limit the performance of the multi-frequency probe (MFP) based coherent optical time domain reflectometry (C-OTDR) are investigated.Based on theoretical analysis and experimental results,compared with conventional C-OTDR,when the probe pulse has power gradient within the pulse width,self-phase modulation (SPM) and cross-phase modulation (XPM) are strengthened in the new COTDR scheme.The generation of four-wave mixing (FWM) is dependent on SPM and XPM,and with modulation frequency of phase modulator higher than 40 MHz,the stimulated Brillouin scattering (SBS) threshold can be enhanced by more than 5 dB,which benefits the maximum dynamic range of the MFP C-OTDR.

  7. Optical diagnostic suite (schlieren, interferometry, and grid image refractometry) on OMEGA EP using a 10-ps, 263-nm probe beam

    Energy Technology Data Exchange (ETDEWEB)

    Froula, D. H.; Boni, R.; Bedzyk, M.; Craxton, R. S.; Ehrne, F.; Ivancic, S.; Jungquist, R.; Shoup, M. J.; Theobald, W.; Weiner, D. [Laboratory for Laser Energetics, University of Rochester, 250 E. River Rd., Rochester, New York 14616 (United States); Kugland, N. L.; Rushford, M. C. [Lawrence Livermore National Laboratory, University of California, P. O. Box 808, Livermore, California 94551 (United States)

    2012-10-15

    A 10-ps, 263-nm (4{omega}) laser is being built to probe plasmas produced on the OMEGA EP [J. H. Kelly, L. J. Waxer, V. Bagnoud, I. A. Begishev, J. Bromage, B. E. Kruschwitz, T. E. Kessler, S. J. Loucks, D. N. Maywar, R. L. McCrory et al., J. Phys. IV France 133, 75-80 (2006)]. A suite of optical diagnostics (schlieren, interferometry, and grid image refractometry) has been designed to diagnose and characterize a wide variety of plasmas. Light scattered by the probe beam is collected by an f/4 catadioptric telescope and a transport system is designed to image with a near-diffraction-limited resolution ({approx}1 -{mu}m full width at half maximum) over a 5-mm field of view to a diagnostic table. The transport system provides a contrast greater than 1 : 10{sup 4} with respect to all wavelengths outside of the 263 {+-} 2 nm measurement range.

  8. Optical diagnostic suite (schlieren, interferometry, and grid image refractometry) on OMEGA EP using a 10-ps, 263-nm probe beam

    Energy Technology Data Exchange (ETDEWEB)

    Froula, D. H.; Boni, R.; Bedzyk, M.; Craxton, R. S.; Ehrne, F.; Ivancic, S.; Jungquist, R.; Shoup, M. J.; Theobald, W.; Weiner, D.; Kugland, N. L.; Rushford, M. C.

    2012-10-01

    A 10-ps, 263-nm (4ω) laser is being built to probe plasmas produced on the OMEGA EP. A suite of optical diagnostics (schlieren, interferometry, and grid image refractometry) has been designed to diagnose and characterize a wide variety of plasmas. Light scattered by the probe beam is collected by an f/4 catadioptric telescope and a transport system is designed to image with a near-diffraction-limited resolution (~1 - μm full width at half maximum) over a 5-mm field of view to a diagnostic table. The transport system provides a contrast greater than 1 : 104 with respect to all wavelengths outside of the 263 ± 2 nm measurement range.

  9. Optical diagnostic suite (schlieren, interferometry, and grid image refractometry) on OMEGA EP using a 10-ps, 263-nm probe beam.

    Science.gov (United States)

    Froula, D H; Boni, R; Bedzyk, M; Craxton, R S; Ehrne, F; Ivancic, S; Jungquist, R; Shoup, M J; Theobald, W; Weiner, D; Kugland, N L; Rushford, M C

    2012-10-01

    A 10-ps, 263-nm (4ω) laser is being built to probe plasmas produced on the OMEGA EP [J. H. Kelly, L. J. Waxer, V. Bagnoud, I. A. Begishev, J. Bromage, B. E. Kruschwitz, T. E. Kessler, S. J. Loucks, D. N. Maywar, R. L. McCrory et al., J. Phys. IV France 133, 75-80 (2006)]. A suite of optical diagnostics (schlieren, interferometry, and grid image refractometry) has been designed to diagnose and characterize a wide variety of plasmas. Light scattered by the probe beam is collected by an f/4 catadioptric telescope and a transport system is designed to image with a near-diffraction-limited resolution (~1 - μm full width at half maximum) over a 5-mm field of view to a diagnostic table. The transport system provides a contrast greater than 1 : 10(4) with respect to all wavelengths outside of the 263 ± 2 nm measurement range.

  10. Brillouin optical time-domain analyzer based on orthogonally-polarized four-tone probe wave.

    Science.gov (United States)

    Hong, Xiaobin; Lin, Wenqiao; Yang, Zhisheng; Wang, Sheng; Wu, Jian

    2016-09-01

    The tolerance of the non-local effect in the BOTDA method using a dual-tone probe wave with fixed frequency separation is theoretically and experimentally investigated in this paper. The presented analysis points out that when the sensing fiber consists of two long fiber segments with large BFS difference (> 100 MHz), there will always be only one probe tone interacting with the pump pulse in the front fiber segment. Therefore, although the pulse distortion problem can still be overcome in this case, the conventional non-local effect would impose systematic error on the estimated BFS of the hotspot located at the end of the front fiber segment. For the purpose of avoiding the impact of non-local effect and eliminating the pump distortion problem simultaneously when using high probe power, a novel method based on a four-tone probe wave is proposed, in which the probe light consists of two pairs of orthogonally-polarized dual-tone probe waves with opposite frequency scanning direction. The experimental results demonstrate that the proposed method is capable of realizing 2 m spatial resolution over 104-km-long sensing fiber without the impact of non-local effect.

  11. 350-μm side-view optical probe for imaging the murine brain in vivo from the cortex to the hypothalamus

    Science.gov (United States)

    Kim, Jun Ki; Choi, Jin Woo; Yun, Seok Hyun

    2013-05-01

    Miniature endoscopic probes offer a solution for deep brain imaging by overcoming the limited depth of intravital microscopy. We describe a small-diameter (350 μm) graded-index optical probe with a side-view design for in vivo cellular imaging of the mammalian brain. The side-view probe provides a unique view of the vertical network of neurons and penetrating blood vessels. At a given insertion site, the translational and rotational scanning of the probe provides access to a large tissue area (>) across the cortex, hippocampus, thalamus, and hypothalamus.

  12. Probing of ultrahigh optical Q-factors of individual liquid microdroplets on superhydrophobic surfaces using tapered optical fiber waveguides

    OpenAIRE

    Jonas, Alexandr; Karadağ, Yasin ; Kiraz, Alper; Mestre, Michael

    2012-01-01

    We report measurements of ultrahigh quality factors (Q-factors) of the optical whispering-gallery modes excited via a tapered optical-fiber waveguide in single glycerol-water microdroplets standing on a superhydrophobic surface in air. Owing to the high contact angle of the glycerol-water mixture on the superhydrophobic surface (>155 degrees), microdroplets with the geometry of a truncated sphere minimally distorted by gravity and contact line pinning effects could be generated. Q-factors up ...

  13. Through nanohole formation in thin metallic film by single nanosecond laser pulses using optical dielectric apertureless probe.

    Science.gov (United States)

    Kulchin, Y N; Vitrik, O B; Kuchmizhak, A A; Nepomnyashchii, A V; Savchuk, A G; Ionin, A A; Kudryashov, S I; Makarov, S V

    2013-05-01

    Separate nanoholes with the minimum size down to 35 nm (~λ/15) and nanohole arrays with the hole size about 100 nm (~λ/5) were fabricated in a 50 nm optically "thick" Au/Pd film, using single 532 nm pump nanosecond laser pulses focused to diffraction-limited spots by a specially designed apertureless dielectric fiber probe. Nanohole fabrication in the metallic film was found to result from lateral heat diffusion and center-symmetrical lateral expulsion of the melt by its vapor recoil pressure. The optimized apertureless dielectric microprobe was demonstrated to enable laser fabrication of deep through nanoholes.

  14. Use of scanning near-field optical microscope with an aperture probe for detection of luminescent nanodiamonds

    Science.gov (United States)

    Shershulin, V. A.; Samoylenko, S. R.; Shenderova, O. A.; Konov, V. I.; Vlasov, I. I.

    2017-02-01

    The suitability of scanning near-field optical microscopy (SNOM) to image photoluminescent diamond nanoparticles with nanoscale resolution is demonstrated. Isolated diamond nanocrystals with an average size of 100 nm, containing negatively charged nitrogen-vacancy (NV-) centers, were chosen as tested material. The NV- luminescence was stimulated by continuous 532 nm laser light. Sizes of analyzed crystallites were monitored by an atomic force microscope. The lateral resolution of the order of 100 nm was reached in SNOM imaging of diamond nanoparticles using 150 nm square aperture of the probe.

  15. Measurement of intracellular pH (pH i) in a single cell using fluorescent probe and fiber optic nanoprobe

    Science.gov (United States)

    Chen, Qinmiao; Qiu, Yishen; Chen, Zhihao; Fang, Na; Li, Gaoming

    2007-11-01

    An optical system for measurement of the intracellular pH (pHi) in a single living cell by using the fluorescent probe, 5(6)-carboxyfluorescein diacetate (CFDA) and fiber optic nanoprobe was demonstrated in this work. The CFDA probe is used to determine pHi in the yeast, Saccharomyces cerevisiae 97 while fiber optic nanoprobe is used to guide excitation light and receive emission light within a single cell. Experimental results showed that our system had higher detection sensitivity than other standard spectrometer, which is important to single-cell analysis, especially for the microanalysis in a single-cell.

  16. Fluorescence correlation spectroscopy of CdSe/ZnS quantum dot optical bioimaging probes with ultra-thin biocompatible coatings.

    Science.gov (United States)

    Murcia, Michael J; Shaw, David L; Long, Eric C; Naumann, Christoph A

    2008-04-01

    The current study reports on the colloidal stabilities and emission properties of CdSe/ZnS quantum dot (QD) optical probes capped with a variety of thin, hydrophilic surface coatings as studied using confocal fluorescence correlation spectroscopy. These coatings are based on mercaptoethanol, mercaptopropionic acid (with and without conjugated aminoethoxyethanol), lipopolymers (DSPE-PEG2000), cysteine (Cys), and a variety of Xaa-Cys dipeptides. The study shows that several types of QDs with thin hydrophilic coatings can be designed that combine good colloidal stability and excellent emission properties (brightness). Furthermore, there is a general correlation between colloidal stability and brightness. The experiments reported herein illustrate that QDs with multiple types of thin coatings can be created for optical imaging applications in a biological environment while also maintaining a size below 10 nm.

  17. Swing arm profilometer: high accuracy testing for large reaction-bonded silicon carbide optics with a capacitive probe

    Science.gov (United States)

    Xiong, Ling; Luo, Xiao; Hu, Hai-xiang; Zhang, Zhi-yu; Zhang, Feng; Zheng, Li-gong; Zhang, Xue-jun

    2017-08-01

    A feasible way to improve the manufacturing efficiency of large reaction-bonded silicon carbide optics is to increase the processing accuracy in the ground stage before polishing, which requires high accuracy metrology. A swing arm profilometer (SAP) has been used to measure large optics during the ground stage. A method has been developed for improving the measurement accuracy of SAP using a capacitive probe and implementing calibrations. The experimental result compared with the interferometer test shows the accuracy of 0.068 μm in root-mean-square (RMS) and maps in 37 low-order Zernike terms show accuracy of 0.048 μm RMS, which shows a powerful capability to provide a major input in high-precision grinding.

  18. Image Processing in Optical Guidance for Autonomous Landing of Lunar Probe

    CERN Document Server

    Meng, Ding; Qing-xian, Wu; Zhen, Zhang

    2008-01-01

    Because of the communication delay between earth and moon, the GNC technology of lunar probe is becoming more important than ever. Current navigation technology is not able to provide precise motion estimation for probe landing control system Computer vision offers a new approach to solve this problem. In this paper, author introduces an image process algorithm of computer vision navigation for autonomous landing of lunar probe. The purpose of the algorithm is to detect and track feature points which are factors of navigation. Firstly, fixation areas are detected as sub-images and matched. Secondly, feature points are extracted from sub-images and tracked. Computer simulation demonstrates the result of algorithm takes less computation and fulfils requests of navigation algorithm.

  19. Development of Ultrasonic Modulation Probe for Fluorescence Tomography Based on Acousto-Optic Effect

    Directory of Open Access Journals (Sweden)

    Trinh Quang Duc

    2011-01-01

    Full Text Available We have developed an ultrasonic probe for fluorescence modulation to image fluorescence within biological tissues. The probe consists of a focused ultrasonic transducer mounted on actuators for mechanical fan scanning, which can be used in contact with the measuring object aiming for clinical application. The mechanical fan scanning employed in the probe has a beneficial feature of portability. As a result, fluorescent beads, which were localized with the diameter of 2 mm at 20 mm depth in a pork meat tissue, were detected with resolution of 3 mm. The system performance denotes the feasibility of development towards the final goal of ultrasonic fluorescence modulation tomography for clinical applications.

  20. Optical luminescence spectroscopy as a probe of the surface mineralogy of Mars

    Science.gov (United States)

    Treiman, A. H.

    1992-01-01

    Optical luminescence (OpL) spectroscopy is an attractive use of a visible-near-IR spectrometer on a Mars lander because mineral products of atmosphere-surface interactions on Mars will probably have characteristic OpL spectra. Optical luminescence spectra would be taken at night, when a spectrometer might otherwise sit idle. Also needed would be a source of exciting radiation, which could be shared with other experiments. Optical luminescence is emission of nonthermal optical photons (near-UV through near-IR) as a response to energy input. On absorption of energy, an atom (or ion) will enter an excited state. The favored decay of many such excited states involving valence-band electrons is emission of an optical photon. Optical luminescence spectra can be useful in determining mineralogy and mineral composition. Optical luminescence in crystals can arise from essential elements (or ions), trace-element substituents (activators), or defects. Common activators in salts of alkali and alkaline earth elements include Mn(2+)(VI), other transition metals, the rare earths, and the actinides. Trace substituents of other species can enhance or quench OpL (e.g., Pb(2+) vs. Fe(3+)). Optical luminescence can also arise from defects in crystal structures, including those caused by radiation and shock.

  1. Investigation of Surface Breakdown on Semiconductor Devices Using Optical Probing Techniques.

    Science.gov (United States)

    1990-01-01

    18] L. Bovino , T. Burke, R. Youmans, M. Weiner, and J. Car, r, "Recent Advances in Optically C’ntrolled Bulk Semiconductor Switches," Digest of...Comp. Simul. 5 (3), 175 (1988). [321 M. Weiner, L. Bovino , R. Youmans, and T. Burke, "Modeling of the Optically Conrolled Semiconductor Switch," J

  2. Optical probing of long-range spatial correlation and symmetry in complex biophotonic architectures on transparent insect wings

    Science.gov (United States)

    Kumar, Pramod; Shamoon, Danish; Singh, Dhirendra P.; Mandal, Sudip; Singh, Kamal P.

    2015-02-01

    We experimentally probe the structural organization of complex bio-photonic architecture on transparent insect wings by a simple, non-invasive, real-time optical technique. A stable and reproducible far-field diffraction pattern in transmission was observed using collimated cw and broadband fs laser pulses. A quantitative analysis of the observed diffraction pattern unveiled long-range quasi-periodic order in the arrangement of the microstructures over mm scale. These observations agree well with the Fourier analysis of SEM images of the wing taken at various length scales. We propose a simple quantitative model based on optical diffraction by an array of non overlapping microstructures with minimal disorder which supports our experimental observations. We observed a rotation of the original diffraction profile by scanning the laser beam across the wing sample which gives direct signature of organizational symmetry in microstructure arrangements at various length scales. In addition, we report the first optical detection of reorganization in the photonic architecture on the Drosophila wings by various genetic mutations. These results have potential for the design and development of diffractive optical components for applied photonics and may open up new opportunities in biomimetic device research.

  3. Development and Optical Testing of the Camera, Hand Lens, and Microscope Probe with Scannable Laser Spectroscopy (CHAMP-SLS)

    Science.gov (United States)

    Mungas, Greg S.; Gursel, Yekta; Sepulveda, Cesar A.; Anderson, Mark; La Baw, Clayton; Johnson, Kenneth R.; Deans, Matthew; Beegle, Luther; Boynton, John

    2008-01-01

    Conducting high resolution field microscopy with coupled laser spectroscopy that can be used to selectively analyze the surface chemistry of individual pixels in a scene is an enabling capability for next generation robotic and manned spaceflight missions, civil, and military applications. In the laboratory, we use a range of imaging and surface preparation tools that provide us with in-focus images, context imaging for identifying features that we want to investigate at high magnification, and surface-optical coupling that allows us to apply optical spectroscopic analysis techniques for analyzing surface chemistry particularly at high magnifications. The camera, hand lens, and microscope probe with scannable laser spectroscopy (CHAMP-SLS) is an imaging/spectroscopy instrument capable of imaging continuously from infinity down to high resolution microscopy (resolution of approx. 1 micron/pixel in a final camera format), the closer CHAMP-SLS is placed to a feature, the higher the resultant magnification. At hand lens to microscopic magnifications, the imaged scene can be selectively interrogated with point spectroscopic techniques such as Raman spectroscopy, microscopic Laser Induced Breakdown Spectroscopy (micro-LIBS), laser ablation mass-spectrometry, Fluorescence spectroscopy, and/or Reflectance spectroscopy. This paper summarizes the optical design, development, and testing of the CHAMP-SLS optics.

  4. Development and Optical Testing of the Camera, Hand Lens, and Microscope Probe with Scannable Laser Spectroscopy (CHAMP-SLS)

    Science.gov (United States)

    Mungas, Greg S.; Gursel, Yekta; Sepulveda, Cesar A.; Anderson, Mark; La Baw, Clayton; Johnson, Kenneth R.; Deans, Matthew; Beegle, Luther; Boynton, John

    2008-01-01

    Conducting high resolution field microscopy with coupled laser spectroscopy that can be used to selectively analyze the surface chemistry of individual pixels in a scene is an enabling capability for next generation robotic and manned spaceflight missions, civil, and military applications. In the laboratory, we use a range of imaging and surface preparation tools that provide us with in-focus images, context imaging for identifying features that we want to investigate at high magnification, and surface-optical coupling that allows us to apply optical spectroscopic analysis techniques for analyzing surface chemistry particularly at high magnifications. The camera, hand lens, and microscope probe with scannable laser spectroscopy (CHAMP-SLS) is an imaging/spectroscopy instrument capable of imaging continuously from infinity down to high resolution microscopy (resolution of approx. 1 micron/pixel in a final camera format), the closer CHAMP-SLS is placed to a feature, the higher the resultant magnification. At hand lens to microscopic magnifications, the imaged scene can be selectively interrogated with point spectroscopic techniques such as Raman spectroscopy, microscopic Laser Induced Breakdown Spectroscopy (micro-LIBS), laser ablation mass-spectrometry, Fluorescence spectroscopy, and/or Reflectance spectroscopy. This paper summarizes the optical design, development, and testing of the CHAMP-SLS optics.

  5. Use of NIRS technology with a remote reflectance fibre-optic probe for predicting major components in bee pollen.

    Science.gov (United States)

    González-Martín, I; Hernández-Hierro, J M; Barros-Ferreiro, N; Cordón Marcos, C; García-Villanova, R J

    2007-05-15

    In the present work, we study the use of near infra-red spectroscopy (NIRS) technology together with a remote reflectance fibre-optic probe for determination of the major components in bee pollen. The method allows immediate control of the bee pollen without prior sample treatment or destruction through direct application of the fibre-optic probe to the sample. The regression method employed was modified partial least squares (MPLS). The calibration results obtained using 45 samples of bee pollen allowed the measurement of protein, moisture, ash, reducing sugars, and pH with multiple correlation coefficients (RSQ) and prediction corrected standard errors (SEPC) of 0.91, 0.56% for protein, of 0.78 and 0.49% for moisture; 0.92 and 0.049% for ash; 0.81 and 1.32g of glucose/100g of bee pollen; 0.84 and 0.15 for pH, respectively. The prediction capacity of the pattern was checked by applying it to samples of unknown pollen in external validation.

  6. An electro-optical timing diagnostic for pump-probe experiments at the free-electron laser in Hamburg FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Azima, Armin

    2009-07-15

    Femtosecond pump-probe experiments have extensively been used to follow atomic and molecular motion in time. The very intense extreme ultraviolet XUV light of the Free electron LASer in Hamburg FLASH facility allows to investigate fundamental processes such as direct one or few photon inner shell ionizations. A supplementary Ti:Sapphire near infrared femtosecond laser system allows to perform two-color pump-probe experiments with FLASH involving intense laser fields of hugely different photon energies. Within this work a bunch arrival measurement system has been built, which assists these two-color pump-probe experiments to reduce the temporal jitter of FLASH and to increase the temporal resolution. The diagnostic is based upon an electro-optical detection scheme and measures the relative arrival time between the Ti:Sapphire femtosecond pulse and the electron bunch, which generates the self-amplified by stimulated emission SASE XUV pulse in the undulator section of FLASH. Key feature of the diagnostic is a 150 m long glass fiber pulse transport line, which inflicts non-linear dispersion. A dispersion control system to compensate for this higher order dispersion has been developed including the control and programming of a spatial light phase modulator. It was possible to transport a 90 fs FWHM short near infrared femtosecond laser pulse Fourier limited by the dispersion compensated glass fiber. The electro-optical signal induced by the FLASH electron bunch was generated, characterized and optimized. The signal features beside the designated bunch arrival timing capability the additional possibility to measure the longitudinal electron bunch density distribution of an arbitrary bunch of FLASH in a single shot with a temporal resolution of below 100 fs RMS. Timing and bunch analysis capabilities of the developed diagnostic have been cross-checked with other comparable diagnostics at FLASH like the transversal deflecting cavity structure named LOLA. Finally, the

  7. Probing the dispersion properties of 1D nanophotonic waveguides with far-field Fourier optics

    DEFF Research Database (Denmark)

    Le Thomas, N.; Jágerská, J.; Houdré, R.

    2008-01-01

    We present an advanced Fourier space imaging technique to probe guided light in nanophotonic structures with an effective numerical aperture of 2.5. This superresolution technique allows us to successfully investigate the dispersive properties of 1D nanowaveguides such as photonic crystal W1...

  8. Optical probe for determining the fat/lean interface in cuts of meat

    Science.gov (United States)

    Weber, Thomas M.; Callow, Diane S.; Jones, James F.; Kuehl, Michael A.; Spletzer, Barry L.

    2005-02-22

    An apparatus and method for locating the boundary surface between a layer of fatty tissue and lean tissue in a cut of meat, such as beef, such as slabs of meat undergoing trimming and cutting in commercial meet processing facilitates. The invention exploits the fact that fatty tissue and lean tissue have significantly different responses to incident light energy. By gauging the degree to which a generated beam of light is scattered and reflected by the tissues under evaluation, the invention permits the character of the tissue to be ascertained. An incident beam of light, such as green light, is generated and transmitted to a probe tip, which tip is inserted into the cut of meat under investigation. The light beam is emitted into the meat tissues from the probe tip, and then is scattered and reflected by the tissues, whereupon some fraction of the emitted light returns to the probe tip. The returning light energy is transmitted to a detector; relative changes in the returning light transmitted to the detector permit the operator to determine when the probe tip is approaching or penetrating the fat/lean tissue interface.

  9. Detection of optical and mechanical property inhomogeneities in tissue mimicking phantoms using an ultrasound assisted optical probe.

    Science.gov (United States)

    Devi, C Usha; Chandran, R Sreekumari Bharat; Vasu, R Mohan; Sood, Ajay K

    2008-01-01

    We discuss the issue of separating contributions from mechanical and optical properties of a moderately scattering tissue phantom to the modulation depth (M) of intensity autocorrelation measured in an ultrasound-assisted optical tomography system using axial and transverse illuminations. For axial illumination, M is affected by both the displacement and absorption coefficient, more prominently by displacement. But transverse illumination has very little contribution from displacement of scattering centers. Since displacement is related to the elastic property of the insonified region, we show that there is a possibility of separating the contributions from elastic and optical properties of the insonified region using axial and transverse illuminations. The main conclusions of our study using moderately scattering phantoms are: 1. axial illumination is the best for mapping storage modulus inhomogeneities, but M is also affected by optical absorption; 2. transverse illumination is the best for mapping absorption inhomogeneities; and 3. for the practically relevant case of an inclusion with larger storage modulus and absorption, both illuminations produced large contrast in M. When the scattering coefficient is high, the angle dependence of illumination is lost and the present method is shown to fail to separate these contributions based on direction of illumination.

  10. Resonant frequency of the silicon micro-structure of MEMS vector hydrophone in fluid-structure interaction

    Directory of Open Access Journals (Sweden)

    Guojun Zhang

    2015-04-01

    Full Text Available The MEMS vector hydrophone developed by the North University of China has advantages of high Signal to Noise Ratio, ease of array integration, etc. However, the resonance frequency of the MEMS device in the liquid is different from that in the air due to the fluid-structure interaction (FSI. Based on the theory of Fluid-Solid Coupling, a generalized distributed mass attached on the micro-structure has been found, which results in the resonance frequency of the microstructure in the liquid being lower than that in the air. Then, an FSI simulation was conducted by ANSYS software. Finally, the hydrophone was measured by using a shaking table and a vector hydrophone calibration system respectively. Results show that, due to the FSI, the resonance frequency of the MEMS devices of the bionic vector hydrophone in the liquid declines approximately 30% compared to the case in the air.

  11. The Optical Chirality Flux as a Useful Far-Field Probe of Chiral Near Fields

    CERN Document Server

    Poulikakos, Lisa V; McPeak, Kevin M; Burger, Sven; Niegemann, Jens; Hafner, Christian; Norris, David J

    2016-01-01

    To optimize the interaction between chiral matter and highly twisted light, quantities that can help characterize chiral electromagnetic fields near nanostructures are needed. Here, by analogy with Poynting's theorem, we formulate the time-averaged conservation law of optical chirality in lossy dispersive media and identify the optical chirality flux as an ideal far-field observable for characterizing chiral optical near fields. Bounded by the conservation law, we show that it provides precise information, unavailable from circular dichroism spectroscopy, on the magnitude and handedness of highly twisted fields near nanostructures.

  12. Comparison of the Noise Properties of Squeezed Probe Light in Optically Thick and Thin Quantum Coherence Media for Weak and Strong Coupling Lights

    Institute of Scientific and Technical Information of China (English)

    LI Zhong-Hua; LI Yuan; DOU Ya-Fang; GAO Jiang-Rui; ZHANG Jun-Xiang

    2012-01-01

    The output amplitude noises of one squeezed probe light which is at resonance throughout different optical depths media in strong- and weak-coupling-Seld regimes are investigated theoretically. By comparing the output quantum noises for different Rabi frequencies of coupling field and also for different optical depths, it is found that the optimal squeezing preservation of the probe light occurs in an optically thin medium with strong-coupling-field, where we can obtain the output squeezing ciose to the input one at nonzero detection frequency.%The output amplitude noises of one squeezed probe light which is at resonance throughout different optical depths media in strong- and weak-coupling-field regimes are investigated theoretically.By comparing the output quantum noises for different Rabi frequencies of coupling field and also for different optical depths,it is found that the optimal squeezing preservation of the probe light occurs in an optically thin medium with strong-coupling-field,where we can obtain the output squeezing close to the input one at nonzero detection frequency.

  13. RadSensor: Xray Detection by Direct Modulation of an Optical Probe Beam

    Energy Technology Data Exchange (ETDEWEB)

    Lowry, M E; Bennett, C V; Vernon, S P; Bond, T; Welty, R; Behymer, E; Petersen, H; Krey, A; Stewart, R; Kobayashi, N P; Sperry, V; Stephan, P; Reinhardt, C; Simpson, S; Stratton, P; Bionta, R; McKernan, M; Ables, E; Ott, L; Bond, S; Ayers, J.; Landen, O L; Bell, P M

    2003-08-01

    We present a new x-ray detection technique based on optical measurement of the effects of x-ray absorption and electron hole pair creation in a direct band-gap semiconductor. The electron-hole pairs create a frequency dependent shift in optical refractive index and absorption. This is sensed by simultaneously directing an optical carrier beam through the same volume of semiconducting medium that has experienced an xray induced modulation in the electron-hole population. If the operating wavelength of the optical carrier beam is chosen to be close to the semiconductor band-edge, the optical carrier will be modulated significantly in phase and amplitude. This approach should be simultaneously capable of very high sensitivity and excellent temporal response, even in the difficult high-energy xray regime. At xray photon energies near 10 keV and higher, we believe that sub-picosecond temporal responses are possible with near single xray photon sensitivity. The approach also allows for the convenient and EMI robust transport of high-bandwidth information via fiber optics. Furthermore, the technology can be scaled to imaging applications. The basic physics of the detector, implementation considerations, and preliminary experimental data are presented and discussed.

  14. Development of a PVDF low-cost shock-wave hydrophone

    Science.gov (United States)

    Travakkoli, J.; Birer, A.; Cathignol, D.

    1996-05-01

    During a few past years a series of shock-wave generators for lithotripsy and/or tissue destruction studies have been developed in our laboratory. Based on the experiences in shock wave measurements and the drawbacks in existing hydrophones, we have developed a very low-cost, wideband, reproducible shock-wave hydrophone. The key element of this device is the rapidly mounting, disposable PVDF membrane. This is a commercially available PVDF shock gauge which is poled by a patented cyclic poling technique. To obtain the widest possible bandwidth, we have adopted a special coplanar membrane design. The PVDF filmis sandwiched between the surfaces of a P.V.C. and a metallic plate of brass which the latter is in contact with the surrounding medium. On the other hand, the active lead is isolated from medium and it is in contact with an isolating liquid (degassed petroleum) held in a cylindrical chamber over the membrane. By the incorporation of this design, the hydrophone can be used for shock wave measurements even in conductive media like different physiological liquids, with a negligible change of sensitivity.

  15. Human Oral Mucosa Tissue-Engineered Constructs Monitored by Raman Fiber-Optic Probe

    OpenAIRE

    Khmaladze, Alexander; Kuo, Shiuhyang; Kim, Roderick Y; Matthews, Robert V.; Marcelo, Cynthia L.; Feinberg, Stephen E.; Morris, Michael D.

    2014-01-01

    In maxillofacial and oral surgery, there is a need for the development of tissue-engineered constructs. They are used for reconstructions due to trauma, dental implants, congenital defects, or oral cancer. A noninvasive monitoring of the fabrication of tissue-engineered constructs at the production and implantation stages done in real time is extremely important for predicting the success of tissue-engineered grafts. We demonstrated a Raman spectroscopic probe system, its design and applicati...

  16. Probing the Rest-Frame Optical Continuum of z=4.5 Lyman Alpha Emitters with Spitzer

    Science.gov (United States)

    Finkelstein, Keely D.; Malhotra, S.; Rhoads, J. E.; Finkelstein, S. L.; Tilvi, V.; Grogin, N. A.; Pirzkal, N.; Dey, A.; Jannuzi, B. T.; Mobasher, B.; Pakzad, S.; Wang, J.

    2012-01-01

    We present the results from a deep Spitzer Space Telescope survey of more than 100 Lyman alpha emitters (LAEs) at z 4.5, first discovered in the Bootes field of the Large Area Lyman Alpha (LALA) survey. These Spitzer/IRAC observations probe the rest-frame optical continuum emission of these galaxies. We also have in hand NICMOS and WFC3 near-infrared (NIR) data from the Hubble Space Telescope (HST) of a sub-sample of these same galaxies. Of the more than 100 sources targeted with Spitzer, 15 sources are detected in at least two out of the four NICMOS/WFC3 and IRAC bands (1.1, 1.6, 3.6 and 4.5 microns), while another 40 sources are detected in one band. We will present the results from a SED-fitting analysis, using the suite of data in the observed NIR/mid-IR, coupled with deep ground based optical data. LAEs form the faint end of the galaxy luminosity function, thus most studies rely on stacking to constrain the rest-frame optical light, which can wash out variations in the physical properties in individual LAEs. This is the largest sample to date of high-redshift LAEs with measured NIR/IR fluxes, allowing us to place the most robust constraints yet on the spread of physical properties in the LAE population.

  17. A fusion-spliced near-field optical fiber probe using photonic crystal fiber for nanoscale thermometry based on fluorescence-lifetime measurement of quantum dots.

    Science.gov (United States)

    Fujii, Takuro; Taguchi, Yoshihiro; Saiki, Toshiharu; Nagasaka, Yuji

    2011-01-01

    We have developed a novel nanoscale temperature-measurement method using fluorescence in the near-field called fluorescence near-field optics thermal nanoscopy (Fluor-NOTN). Fluor-NOTN enables the temperature distributions of nanoscale materials to be measured in vivo/in situ. The proposed method measures temperature by detecting the temperature dependent fluorescence lifetimes of Cd/Se quantum dots (QDs). For a high-sensitivity temperature measurement, the auto-fluorescence generated from a fiber probe should be reduced. In order to decrease the noise, we have fabricated a novel near-field optical-fiber probe by fusion-splicing a photonic crystal fiber (PCF) and a conventional single-mode fiber (SMF). The validity of the novel fiber probe was assessed experimentally by evaluating the auto-fluorescence spectra of the PCF. Due to the decrease of auto-fluorescence, a six- to ten-fold increase of S/N in the near-field fluorescence lifetime detection was achieved with the newly fabricated fusion-spliced near-field optical fiber probe. Additionally, the near-field fluorescence lifetime of the quantum dots was successfully measured by the fabricated fusion-spliced near-field optical fiber probe at room temperature, and was estimated to be 10.0 ns.

  18. A Fusion-Spliced Near-Field Optical Fiber Probe Using Photonic Crystal Fiber for Nanoscale Thermometry Based on Fluorescence-Lifetime Measurement of Quantum Dots

    Directory of Open Access Journals (Sweden)

    Toshiharu Saiki

    2011-08-01

    Full Text Available We have developed a novel nanoscale temperature-measurement method using fluorescence in the near-field called Fluorescence Near-field Optics Thermal Nanoscopy (Fluor-NOTN. Fluor-NOTN enables the temperature distributions of nanoscale materials to be measured in vivo/in situ. The proposed method measures temperature by detecting the temperature dependent fluorescence lifetimes of Cd/Se Quantum Dots (QDs. For a high-sensitivity temperature measurement, the auto-fluorescence generated from a fiber probe should be reduced. In order to decrease the noise, we have fabricated a novel near-field optical-fiber probe by fusion-splicing a photonic crystal fiber (PCF and a conventional single-mode fiber (SMF. The validity of the novel fiber probe was assessed experimentally by evaluating the auto-fluorescence spectra of the PCF. Due to the decrease of auto-fluorescence, a six- to ten-fold increase of S/N in the near-field fluorescence lifetime detection was achieved with the newly fabricated fusion-spliced near-field optical fiber probe. Additionally, the near-field fluorescence lifetime of the quantum dots was successfully measured by the fabricated fusion-spliced near-field optical fiber probe at room temperature, and was estimated to be 10.0 ns.

  19. Rayleigh scattering in an optical nanofiber as a probe of higher-order mode propagation

    CERN Document Server

    Hoffman, Jonathan E; Beadie, Guy; Rolston, Steven L; Orozco, Luis A

    2015-01-01

    Optical nanofibers provide a rich platform for exploring atomic and optical phenomena even when they support only a single spatial mode. Nanofibers supporting higher-order modes provide additional degrees of freedom to enable complex evanescent field profiles for interaction with the surrounding medium, but local control of these profiles requires nondestructive evaluation of the propagating fields. Here, we use Rayleigh scattering for rapid measurement of the propagation of light in few-mode optical nanofibers. Imaging the Rayleigh scattered light provides direct visualization of the spatial evolution of propagating fields throughout the entire fiber, including the transition from core-cladding guidance to cladding-air guidance. We resolve the interference between higher-order modes to determine local beat lengths and modal content along the fiber, and show that the modal superposition in the waist can be systematically controlled by adjusting the input superposition. With this diagnostic we can measure vari...

  20. Optical probe of Heisenberg-Kitaev magnetism in α -RuCl3

    Science.gov (United States)

    Sandilands, Luke J.; Sohn, C. H.; Park, H. J.; Kim, So Yeun; Kim, K. W.; Sears, Jennifer A.; Kim, Young-June; Noh, Tae Won

    2016-11-01

    We report a temperature-dependent optical spectroscopic study of the Heisenberg-Kitaev magnet α -RuCl3 . Our measurements reveal anomalies in the optical response near the magnetic ordering temperature. At higher temperatures, we observe a redistribution of spectral weight over a broad energy range that is associated with nearest-neighbor spin-spin correlations. This finding is consistent with highly frustrated magnetic interactions and in agreement with theoretical expectations for this class of material. The optical data also reveal significant electron-hole interaction effects, including a bound excitonic state. These results demonstrate a clear coupling between charge and spin degrees of freedom and provide insight into the properties of thermally disordered Heisenberg-Kitaev magnets.

  1. Probing Aromaticity of Borozene Through Optical and Dielectric Response: A Theoretical Study

    CERN Document Server

    Sahu, Sridhar

    2009-01-01

    In this work, we report electronic structure calculations aimed at computing the linear optical absorption spectrum, and static dipole polarizablity of a newly proposed boron-based planar aromatic compound borozene (B_12H_6$. For the purpose, we use the semiempirical INDO model Hamiltonian, accompanied by large-scale correlation calculations using the multi-reference singles-doubles configuration-interaction (MRSDCI) approach. We present detailed predictions about the energetics, polarization properties, and the nature of many-particle states contributing to various peaks in the linear absorption spectrum. Our results can be used to characterize this material in future optical absorption experiments. We also argue that one can deduce the aromaticity of the cluster from the optical absorption and static polarizability results.

  2. Reconstruction of elongated bubbles fusing the information from multiple optical probes through a Bayesian inference technique.

    Science.gov (United States)

    Chakraborty, Shubhankar; Roy Chaudhuri, Partha; Das, Prasanta Kr

    2016-07-01

    In this communication, a novel optical technique has been proposed for the reconstruction of the shape of a Taylor bubble using measurements from multiple arrays of optical sensors. The deviation of an optical beam passing through the bubble depends on the contour of bubble surface. A theoretical model of the deviation of a beam during the traverse of a Taylor bubble through it has been developed. Using this model and the time history of the deviation captured by the sensor array, the bubble shape has been reconstructed. The reconstruction has been performed using an inverse algorithm based on Bayesian inference technique and Markov chain Monte Carlo sampling algorithm. The reconstructed nose shape has been compared with the true shape, extracted through image processing of high speed images. Finally, an error analysis has been performed to pinpoint the sources of the errors.

  3. Optical and microwave communications system conceptual design for a realistic interstellar probe

    Science.gov (United States)

    Boone, Bradley G.; Bokulic, Robert S.; Andrews, G. B.; McNutt, Ralph L., Jr.; Dagalakis, Nicholas G.

    2002-12-01

    The concept of a realistic interstellar explorer has been addressed by the Johns Hopkins University Applied Physics Laboratory with support from the NASA Institute for Advanced Concepts. This paper discusses the requirements, conceptual design and technology issues associated with the optical and RF communications systems envisioned for this mission, in which the spacecraft has a projected range of 1000 AU. Well before a range of 100 AU interactive control of the spacecraft becomes nearly impossible, necessitating a highly autonomous craft and one-way communications to Earth. An approach is taken in which the role of the optical downlink is emphasized for data transfer and that of the microwave uplink emphasized for commands. The communication system is strongly influenced by the large distances involved, the high velocities as well as the requirements for low-mass, low prime power, reliability, and spacecraft autonomy. An optical terminal concept is described that has low mass and prime power in a highly integrated and novel architecture, but new technologies are needed to meet the range, mass, and power requirements. These include high-power, 'wall-plug' efficient diode-pumped fiber lasers; compact, lightweight, and low-power micro-electromechanical (MEM) beam steering elements; and lightweight diffractive quasi-membrane optics. In addition, a very accurate star tracking mechanism must be fully integrated with the laser downlink to achieve unprecedented pointing accuracy. The essential optical, structural, mechanical, and electronic subsystems are described that meet the mission requirements, and the key features of advanced technologies that need to be developed are discussed. The conclusion from this preliminary effort is that an optical communications downlink out to 1000 astronomical units is within the realm of technical feasibility in the next 5-10 years if the identified technical risks for the new technologies can be retired.

  4. Probing single processive molecular motors with high-speed optical tweezers and fluorescence microscopy

    Science.gov (United States)

    Gardini, L.; Pavone, F. S.; Capitanio, M.

    2017-02-01

    Here we present development of optical techniques for the study of single processive myosin motors based on the combination of high-speed optical tweezers force spectroscopy and single molecule fluorescence imaging. Ultrafast force-clamp spectroscopy1 is applied to study the dependence of single chemo-mechanical steps of processive myosin motors on the applied load. On the other hand, single molecule localization through FIONA (Fluorescence Imaging with One Nanometer Accuracy)2, 3 is applied to in vitro motility assay to measure parameters such as the runlength, velocity and step size of single myosin V motors, labeled with Quantum Dots, under unloaded conditions.

  5. Characterization of optically excited semiconductors by phase-resolved pump-probe spectroscopy; Charakterisierung optisch angeregter Halbleiter mit phasenaufgeloester Pump-Probe-Spektroskopie

    Energy Technology Data Exchange (ETDEWEB)

    Seemann, M.

    2005-07-01

    This thesis aims to present new experimentally and theoretically verified statements about the many-body effects in thin Zinc Selenide layers and to discuss the various techniques applied in the experiments. Centred in this thesis is the investigation of ultrafast nonlinear effects in the response of thin Zinc Selenide layers on their optical excitation with ultrashort laser pulses. The experiments address the regime of quantum coherence and thermalisation of the excitation. In the energy range of the band gap the response is determined by the propagation of exciton polaritons in the samples. The dynamics of the interactions between the polaritons and the particles of the solid are investigated by conducting pump-probe experiments. This thesis extends and surpasses previous work in that the reflected light is completely analysed in its classical phase and amplitude. Thus all the information in the electromagnetic field in the temporal and spectral domain is available. It is found that especially not just the power spectrum of the reflected light is much structured but the spectral phase too. The spectral phase reflects directly the carrier-density dependent of the polariton dispersion while the temporal field, characterised by the beating of slowly propagating polaritons, does not show dramatic carrier-density depended changes. Phase resolved measurement of the reflected field is performed with the technique of Spectral Interferometry which is adapted to the experiment and tested on correctness. The measured electromagnetic fields are interpreted with classical and a semi-classical microscopic models. Further is shown how these results relate to recent microscopic quantum mechanical models. (orig.)

  6. Single Cs Atoms as Collisional Probes in a large Rb Magneto-Optical Trap

    CERN Document Server

    Weber, Claudia; Spethmann, Nicolas; Meschede, Dieter; Widera, Artur

    2010-01-01

    We study cold inter-species collisions of Caesium and Rubidium in a strongly imbalanced system with single and few Cs atoms. Observation of the single atom fuorescence dynamics yields insight into light-induced loss mechanisms, while both subsystems can remain in steady-state. This significantly simplifies the analysis of the dynamics, as Cs-Cs collisions are effectively absent and the majority component remains unaffected, allowing us to extract a precise value of the Rb-Cs collision parameter. Extending our results to ground state collisions would allow to use single neutral atoms as coherent probes for larger quantum systems.

  7. Probing the electrical switching of a memristive optical antenna by STEM EELS

    Science.gov (United States)

    Schoen, David T.; Holsteen, Aaron L.; Brongersma, Mark L.

    2016-07-01

    The scaling of active photonic devices to deep-submicron length scales has been hampered by the fundamental diffraction limit and the absence of materials with sufficiently strong electro-optic effects. Plasmonics is providing new opportunities to circumvent this challenge. Here we provide evidence for a solid-state electro-optical switching mechanism that can operate in the visible spectral range with an active volume of less than (5 nm)3 or ~10-6 λ3, comparable to the size of the smallest electronic components. The switching mechanism relies on electrochemically displacing metal atoms inside the nanometre-scale gap to electrically connect two crossed metallic wires forming a cross-point junction. These junctions afford extreme light concentration and display singular optical behaviour upon formation of a conductive channel. The active tuning of plasmonic antennas attached to such junctions is analysed using a combination of electrical and optical measurements as well as electron energy loss spectroscopy in a scanning transmission electron microscope.

  8. Probing half βy* optics in the Accelerator Test Facility 2

    Science.gov (United States)

    Patecki, M.; Bett, D.; Marin, E.; Plassard, F.; Tomás, R.; Kubo, K.; Kuroda, S.; Naito, T.; Okugi, T.; Tauchi, T.; Terunuma, N.

    2016-10-01

    A nanometer beam size at the interaction point (IP) is required for future linear colliders to achieve the desired rate of particle collisions. KEK Accelerator Test Facility 2 (ATF2), a scaled down implementation of the linear collider beam delivery system, serves for demonstrating the feasibility of the final focus system (FFS). An unprecedented low vertical beam size at the IP of about 40 nm has been already measured in ATF2 using the optics with a nominal βy* . In our study we decrease the βy* value in order to investigate the performance of more chromatic optics and to study the limits of beam focusing at the IP. Stronger beam focusing amplifies the aberrations from the final focus imperfections which cause an increase of the beam size at the IP. Simulations show that the multipolar errors and final doublet fringe fields spoil the IP beam sizes for ultralow βy* optics but can be mitigated either by increasing the value of the horizontal β* or installing a pair of octupole magnets. We report on our first experimental steps towards the ultralow βy* in ATF2. New methods for the beam diagnostics at the IP were developed in order to precisely set the desired optics. βy* value was half the nominal value. The beam tuning was performed and the measured beam size is compared with the simulation results.

  9. Probing half β_{y}^{*} optics in the Accelerator Test Facility 2

    Directory of Open Access Journals (Sweden)

    M. Patecki

    2016-10-01

    Full Text Available A nanometer beam size at the interaction point (IP is required for future linear colliders to achieve the desired rate of particle collisions. KEK Accelerator Test Facility 2 (ATF2, a scaled down implementation of the linear collider beam delivery system, serves for demonstrating the feasibility of the final focus system (FFS. An unprecedented low vertical beam size at the IP of about 40 nm has been already measured in ATF2 using the optics with a nominal β_{y}^{*}. In our study we decrease the β_{y}^{*} value in order to investigate the performance of more chromatic optics and to study the limits of beam focusing at the IP. Stronger beam focusing amplifies the aberrations from the final focus imperfections which cause an increase of the beam size at the IP. Simulations show that the multipolar errors and final doublet fringe fields spoil the IP beam sizes for ultralow β_{y}^{*} optics but can be mitigated either by increasing the value of the horizontal β^{*} or installing a pair of octupole magnets. We report on our first experimental steps towards the ultralow β_{y}^{*} in ATF2. New methods for the beam diagnostics at the IP were developed in order to precisely set the desired optics. β_{y}^{*} value was half the nominal value. The beam tuning was performed and the measured beam size is compared with the simulation results.

  10. Optically probed symmetry breaking in the chiral magnet Cu2OSeO3

    NARCIS (Netherlands)

    Versteeg, R. B.; Vergara, I.; Schaefer, S. D.; Bischoff, D.; Aqeel, A.; Palstra, T. T. M.; Grueninger, M.; van Loosdrecht, P. H. M.

    2016-01-01

    We report on the linear optical properties of the chiral magnet Cu2OSeO3, specifically associated with the absence of inversion symmetry, the chiral crystallographic structure, and magnetic order. Through spectroscopic ellipsometry, we observe local crystal-field excitations below the charge-transfe

  11. Accuracy of bubble velocity measurement with a four-point optical fibre probe

    NARCIS (Netherlands)

    Bai, Wei; Deen, Niels G.; Mudde, Robert F.; Kuipers, J.A.M.

    2008-01-01

    For the operation of high void fraction bubbly flows in bubble columns, insight in primary parameters such as bubble size, shape and velocity as well as gas volume fraction is essential. At high gas volume fractions the flow system becomes opaque, ruling out non-intrusive optical techniques. As an a

  12. Optical probing of long range spatial correlation and symmetry in complex biophotonic architectures in the transparent insect wings

    CERN Document Server

    Kumar, Pramod; Singh, Dhirendra P; Mandal, Sudip; Singh, Kamal P

    2013-01-01

    We experimentally probe the natural complex structures in the transparent insect wings by a simple, non-invasive, real time optical technique using monochromatic lasers and broadband femtosecond laser pulses. A stable and reproducible complex diffraction pattern in trans-mission unveils the signature of a new form of spatial correlation and structural symmetry at various length scales for a variety of insect wings. A quantitative analysis of the diffraction reveals a direct link between the structural organization and transmitted diffraction patterns. While matching the sensitivity of SEM for micro-details, our technique is highly efficient to unveil the spatial correlation and symmetry of the photonic architecture from Micrometer to mm scale. Furthermore, when the laser beam is scanned across the wing sample a rotation of the original diffraction profile is observed which quantitatively agrees with the theoretical patterns generated from the corresponding SEM images. Our technique allows us to report the fir...

  13. Fiber optic probes based on silver-only coated hollow glass waveguides for ionizing beam radiation dosimetry

    Science.gov (United States)

    Darafsheh, Arash; Liu, Haoyang; Melzer, Jeffrey E.; Taleei, Reza; Harrington, James A.; Kassaee, Alireza; Zhu, Timothy C.; Finlay, Jarod C.

    2016-03-01

    Čerenkov contamination is a significant issue in radiation detection by fiber-coupled scintillators. To enhance the scintillation signal transmission while minimizing Čerenkov contamination, we designed a fiber probe using a silver-only coated hollow waveguide (HWG). The HWG tip with inserted scintillator, embedded in tissue mimicking phantoms, was irradiated with clinical electron and photon beams. Optical spectra of irradiated tips were taken using a fiber spectrometer, and the signal was deconvolved with a linear fitting algorithm. The resultant decomposed spectra of the scintillator with and without Čerenkov correction were in good agreement with measurements performed by an electron diode and ion chamber for electron and photon beam dosimetry, respectively, indicating the minimal effect of Čerenkov contamination. Compared with a silver/dielectric coated HWG fiber dosimeter design we observed higher signal transmission in our design based on the use of silver-only HWG.

  14. Development of near-field scanning microwave and optical dual probe: Application to characterization of high-T(c) superconductors

    Science.gov (United States)

    Aga, Roberto Sabas, Jr.

    In this dissertation, a novel dual-channel near-field scanning microwave and optical microprobe (NSMM/NSOM) was developed for simultaneous mapping of microwave and optical properties of a sample at microscopic scales. This microprobe is composed of an open-end coaxial resonator with its center conductor being replaced by a stainless steel tube terminated by a titanium/silver coated fiber optic with a tapered tip. The optical fiber serves as the channel for NSOM, while its metal coating is the channel for NSMM. Using this dual-channel NSMM/NSOM probe, a spatial resolution of ˜5 mum, that is comparable to the best reported for single-channel NSMM, has been achieved on metallic samples. This resolution is mainly limited by the sensitivity of the NSMM channel and may be further improved when the sensitivity of NSMM is enhanced. Characterization of the microwave properties of the highest-Tc Hg-based superconductors has been carried out using a traditional resonant cavity technique, as well as a novel single-channel NSMM and the dual-channel NSMM/NSOM. Using the traditional technique, the microwave surface resistance (Rs) and power handling capability (Pc) of HgBa 2CaCu2O6 (Hg-1212 with Tc ˜ 125 K) films have been measured for the first time, and the results are superior to the best achieved on other superconductors. For example, a comparable R s ˜ 0.3 mO (10 GHz) can be obtained on Hg-1212 at close to 120 K as opposed to the same Rs for YBa2Cu3O 7 (the most popular high-Tc superconductor with Tc ˜ 92 K) at around 77K. This can be attributed to the large difference in the Tcs between the two materials and has demonstrated the potential of Hg-1212 for microwave applications. A comparison of the microwave properties of Hg-1212, Tl-2212 and YBCO films at reduced temperature scale suggested further room for improvement of Hg-1212 performance. Using NSMM, the localized microwave properties, such as Tcs, sheet resistance and power handling capability have been investigated

  15. Nanoparticles enhance brain delivery of blood-brain barrier-impermeable probes for in vivo optical and magnetic resonance imaging.

    Science.gov (United States)

    Koffie, Robert M; Farrar, Christian T; Saidi, Laiq-Jan; William, Christopher M; Hyman, Bradley T; Spires-Jones, Tara L

    2011-11-15

    Several imaging modalities are suitable for in vivo molecular neuroimaging, but the blood-brain barrier (BBB) limits their utility by preventing brain delivery of most targeted molecular probes. We prepared biodegradable nanocarrier systems made up of poly(n-butyl cyanoacrylate) dextran polymers coated with polysorbate 80 (PBCA nanoparticles) to deliver BBB-impermeable molecular imaging probes into the brain for targeted molecular neuroimaging. We demonstrate that PBCA nanoparticles allow in vivo targeting of BBB-impermeable contrast agents and staining reagents for electron microscopy, optical imaging (multiphoton), and whole brain magnetic resonance imaging (MRI), facilitating molecular studies ranging from individual synapses to the entire brain. PBCA nanoparticles can deliver BBB-impermeable targeted fluorophores of a wide range of sizes: from 500-Da targeted polar molecules to 150,000-Da tagged immunoglobulins into the brain of living mice. The utility of this approach is demonstrated by (i) development of a "Nissl stain" contrast agent for cellular imaging, (ii) visualization of amyloid plaques in vivo in a mouse model of Alzheimer's disease using (traditionally) non-BBB-permeable reagents that detect plaques, and (iii) delivery of gadolinium-based contrast agents into the brain of mice for in vivo whole brain MRI. Four-dimensional real-time two-photon and MR imaging reveal that brain penetration of PBCA nanoparticles occurs rapidly with a time constant of ∼18 min. PBCA nanoparticles do not induce nonspecific BBB disruption, but collaborate with plasma apolipoprotein E to facilitate BBB crossing. Collectively, these findings highlight the potential of using biodegradable nanocarrier systems to deliver BBB-impermeable targeted molecular probes into the brain for diagnostic neuroimaging.

  16. Nanoparticles enhance brain delivery of blood–brain barrier-impermeable probes for in vivo optical and magnetic resonance imaging

    Science.gov (United States)

    Koffie, Robert M.; Farrar, Christian T.; Saidi, Laiq-Jan; William, Christopher M.; Hyman, Bradley T.; Spires-Jones, Tara L.

    2011-01-01

    Several imaging modalities are suitable for in vivo molecular neuroimaging, but the blood–brain barrier (BBB) limits their utility by preventing brain delivery of most targeted molecular probes. We prepared biodegradable nanocarrier systems made up of poly(n-butyl cyanoacrylate) dextran polymers coated with polysorbate 80 (PBCA nanoparticles) to deliver BBB-impermeable molecular imaging probes into the brain for targeted molecular neuroimaging. We demonstrate that PBCA nanoparticles allow in vivo targeting of BBB-impermeable contrast agents and staining reagents for electron microscopy, optical imaging (multiphoton), and whole brain magnetic resonance imaging (MRI), facilitating molecular studies ranging from individual synapses to the entire brain. PBCA nanoparticles can deliver BBB-impermeable targeted fluorophores of a wide range of sizes: from 500-Da targeted polar molecules to 150,000-Da tagged immunoglobulins into the brain of living mice. The utility of this approach is demonstrated by (i) development of a “Nissl stain” contrast agent for cellular imaging, (ii) visualization of amyloid plaques in vivo in a mouse model of Alzheimer's disease using (traditionally) non–BBB-permeable reagents that detect plaques, and (iii) delivery of gadolinium-based contrast agents into the brain of mice for in vivo whole brain MRI. Four-dimensional real-time two-photon and MR imaging reveal that brain penetration of PBCA nanoparticles occurs rapidly with a time constant of ∼18 min. PBCA nanoparticles do not induce nonspecific BBB disruption, but collaborate with plasma apolipoprotein E to facilitate BBB crossing. Collectively, these findings highlight the potential of using biodegradable nanocarrier systems to deliver BBB-impermeable targeted molecular probes into the brain for diagnostic neuroimaging. PMID:22065785

  17. Highly precise and accurate terahertz polarization measurements based on electro-optic sampling with polarization modulation of probe pulses.

    Science.gov (United States)

    Nemoto, Natsuki; Higuchi, Takuya; Kanda, Natsuki; Konishi, Kuniaki; Kuwata-Gonokami, Makoto

    2014-07-28

    We have developed an electro-optic (EO) sampling method with polarization modulation of probe pulses; this method allows us to measure the direction of a terahertz (THz) electric-field vector with a precision of 0.1 mrad in a data acquisition time of 660 ms using a 14.0-kHz repetition rate pulsed light source. Through combination with a THz time-domain spectroscopy technique, a time-dependent two-dimensional THz electric field was obtained. We used a photoelastic modulator for probe-polarization modulation and a (111)-oriented zincblende crystal as the EO crystal. Using the tilted pulse front excitation method with stable regeneratively amplified pulses, we prepared stable and intense THz pulses and performed pulse-by-pulse analog-to-digital conversion of the signals. These techniques significantly reduced statistical errors and enabled sub-mrad THz polarization measurements. We examined the performance of this method by measuring a wire-grid polarizer as a sample. The present method will open a new frontier of high-precision THz polarization sensitive measurements.

  18. Intraoperative handheld probe for 3D imaging of pediatric benign vocal fold lesions using optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Benboujja, Fouzi; Garcia, Jordan; Beaudette, Kathy; Strupler, Mathias; Hartnick, Christopher J.; Boudoux, Caroline

    2016-02-01

    Excessive and repetitive force applied on vocal fold tissue can induce benign vocal fold lesions. Children affected suffer from chronic hoarseness. In this instance, the vibratory ability of the folds, a complex layered microanatomy, becomes impaired. Histological findings have shown that lesions produce a remodeling of sup-epithelial vocal fold layers. However, our understanding of lesion features and development is still limited. Indeed, conventional imaging techniques do not allow a non-invasive assessment of sub-epithelial integrity of the vocal fold. Furthermore, it remains challenging to differentiate these sub-epithelial lesions (such as bilateral nodules, polyps and cysts) from a clinical perspective, as their outer surfaces are relatively similar. As treatment strategy differs for each lesion type, it is critical to efficiently differentiate sub-epithelial alterations involved in benign lesions. In this study, we developed an optical coherence tomography (OCT) based handheld probe suitable for pediatric laryngological imaging. The probe allows for rapid three-dimensional imaging of vocal fold lesions. The system is adapted to allow for high-resolution intra-operative imaging. We imaged 20 patients undergoing direct laryngoscopy during which we looked at different benign pediatric pathologies such as bilateral nodules, cysts and laryngeal papillomatosis and compared them to healthy tissue. We qualitatively and quantitatively characterized laryngeal pathologies and demonstrated the added advantage of using 3D OCT imaging for lesion discrimination and margin assessment. OCT evaluation of the integrity of the vocal cord could yield to a better pediatric management of laryngeal diseases.

  19. Effect of low intensity laser interaction with human skin fibroblast cells using fiber-optic nano-probes.

    Science.gov (United States)

    Pal, Gopalendu; Dutta, Ashim; Mitra, Kunal; Grace, Michael S; Amat, Albert; Romanczyk, Tara B; Wu, Xingjia; Chakrabarti, Kristi; Anders, Juanita; Gorman, Erik; Waynant, Ronald W; Tata, Darrell B

    2007-03-01

    Over the past forty years, many efforts have been devoted to study low power laser light interactions with biological systems. Some of the investigations were performed in-vitro, on bulk cell populations. Our present work was undertaken to apply specially engineered fiber-optic based nano-probes for the precise delivery of laser light on to a single cell and to observe production of low power laser light induced reactive oxygen species (ROS). A normal human skin fibroblast (NHF) cell line was utilized in this investigation and the cells were irradiated under two different schemes of exposure: (1) an entire NHF cell population within a Petri dish using a fan beam methodology, and (2) through the precise delivery of laser energy on to a single NHF cell using fiber-optic nano-probe. Photobiostimulative studies were conducted through variation of laser intensity, exposure time, and the energy dose of exposure. Laser irradiation induced enhancement in the rate of cell proliferation was observed to be dependent on laser exposure parameters and the method of laser delivery. The total energy dose (fluence) had a greater influence on the enhancement in the rate of cellular proliferation than compared to laser intensity. The enhancement in the growth rate was observed to have a finite life-time of several days after the initial laser exposure. Fluorescent life-time imaging of ROS was performed during the nano-based single cell exposure method. The kinetics of ROS generation was found to depend strongly on the laser fluence and not on the laser intensity.

  20. Combining elastic and resonant inelastic optical spectroscopies for multiscale probing of embedded nanoparticle architectures

    Science.gov (United States)

    Farcau, Cosmin; Bonafos, Caroline; Benzo, Patrizio; Benassayag, Gerard; Carles, Robert

    2010-11-01

    Composite materials consisting of metal nanoparticles (NPs) embedded in a dielectric matrix have a great potential for photonic and plasmonic applications. A set of expensive, time-consuming, and destructive methods (like electron microscopy, electron energy loss, or secondary ion mass spectroscopy) are extensively being used for the structural characterization of such buried NP assemblies. Here, we show the power of combining complementary, noninvasive optical techniques to characterize planar arrays of Ag NPs embedded in a silica film. We use UV-Vis optical reflectivity and resonant Brillouin-Raman scattering, sustained by simulations, to show the sensitivity of these methods to the presence, density, size distribution, and spatial localization of NPs. The accuracy of the results is validated by transmission electron microscopy investigations. Finally the method is applied to obtain images of embedded plasmonic structures from reflectivity and Raman scanning microscopy.

  1. Laser-induced surface ablation as a probe of optical surface damage mechanisms

    Science.gov (United States)

    Chase, L. L.

    1990-02-01

    The phenomenon of laser surface damage is briefly reviewed, with an emphasis on the fundamental physical mechanisms of the interaction of laser light with the surface. Recent measurements of laser ablation of charged and neutral surface constituents and impurities are described, and it is shown that these experiments can he used to investigate optical damage mechanisms. Crystalline ZnS is used as the primary example of this work.

  2. Optical properties of nitrogen-doped graphene thin films probed by spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Shen, C.C. [Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China); Tseng, C.C.; Lin, C.T.; Li, L.J. [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China); Liu, H.L., E-mail: hliu@ntnu.edu.tw [Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China)

    2014-11-28

    Nitrogen-doped graphene thin films were prepared by either chemical vapor deposition (CVD) or electrochemical exfoliation (ECE). Their optical properties were determined in the spectral region of 0.73–6.42 eV and at temperatures between 200 and 350 K by spectroscopic ellipsometry. The parameters of the dispersive structures were derived by numerical fitting of the experimental data to the stacked layer model. The optical absorption spectrum of the CVD-grown thin films is characterized by an asymmetric Fano resonance in the ultraviolet frequency region. In contrast, the line shape of the ECE-grown thin films displays less asymmetric. The excitonic resonance of the nitrogen-doped thin films is overall blue shifted by ∼ 0.2–0.3 eV compared with that of undoped analog. We interpret these results in terms of the exothermic nature of triazine molecule adsorption due to binding to graphene's surface via electron rich nitrogen. - Highlights: • Optical properties of N-doped graphene films determined by spectroscopic ellipsometry • Fano resonance in the ultraviolet frequency region of all graphene film absorption spectra • Blueshift in the excitonic resonance of N-doped graphene thin films is observed.

  3. Field enhancement at silicon surfaces by gold ellipsoids probed by optical second-harmonic generation spectroscopy

    Science.gov (United States)

    Ulriksen, Hans Ulrik; Pedersen, Kjeld

    2016-12-01

    Optical second-harmonic generation (SHG) spectroscopy has been used to determine the field enhancements from Au nanoparticles on a silicon substrate. Au particles with diameters from 30 to 250 nm have been deposited on a Si substrate passivated by a 1 nm thick surface oxide. The linear optical spectra are dominated by a horizontal plasmon resonance near 1.0 eV, and the experimental spectra are modelled by the island film model in order to extract the linear properties of the metal particles. SHG spectroscopy from this system shows resonances from the metal particles and from the silicon/oxide substrate. By following the evolution of these Si resonances with the size of the Au particles, the field enhancement in the Si surface has been modelled. The effect of the Au particles on SHG at the Si E1 resonance is a combination of charge transfer through the thin oxide that changes the space charge region and an enhancement of the optical field in a thin surface layer of the Si substrate.

  4. Probing DNA-DNA Interactions with a Combination of Quadruple-Trap Optical Tweezers and Microfluidics.

    Science.gov (United States)

    Brouwer, Ineke; King, Graeme A; Heller, Iddo; Biebricher, Andreas S; Peterman, Erwin J G; Wuite, Gijs J L

    2017-01-01

    DNA metabolism and DNA compaction in vivo involve frequent interactions of remote DNA segments, mediated by proteins. In order to gain insight into such interactions, quadruple-trap optical tweezers have been developed. This technique provides an unprecedented degree of control through the ability to independently manipulate two DNA molecules in three dimensions. In this way, discrete regions of different DNA molecules can be brought into contact with one another, with a well-defined spatial configuration. At the same time, the tension and extension of the DNA molecules can be monitored. Furthermore, combining quadruple-trap optical tweezers with microfluidics makes fast buffer exchange possible, which is important for in situ generation of the dual DNA-protein constructs needed for these kinds of experiments. In this way, processes such as protein-mediated inter-DNA bridging can be studied with unprecedented control. This chapter provides a step-by-step description of how to perform a dual DNA manipulation experiment using combined quadruple-trap optical tweezers and microfluidics.

  5. Hydrodynamics driven by ultrashort laser pulse: simulations and the optical pump—X-ray probe experiment

    Science.gov (United States)

    Inogamov, N. A.; Zhakhovsky, V. V.; Hasegawa, N.; Nishikino, M.; Yamagiwa, M.; Ishino, M.; Agranat, M. B.; Ashitkov, S. I.; Faenov, A. Ya.; Khokhlov, V. A.; Ilnitsky, D. K.; Petrov, Yu. V.; Migdal, K. P.; Pikuz, T. A.; Takayoshi, S.; Eyama, T.; Kakimoto, N.; Tomita, T.; Baba, M.; Minami, Y.; Suemoto, T.; Kawachi, T.

    2015-06-01

    Spatial structures of ablative mass flow produced by femtosecond laser pulses are studied. In experiments with a gold film, the Ti:sapp laser pulse having a focal size of 100 microns on a target was used, while a soft X-ray probe pulse was utilized for diagnostics. The experimental data are compared with simulated mass flows obtained by two-temperature hydrodynamics and molecular dynamics methods. Simulation shows evolution of a thin surface layer pressurized after electron-ion thermalization, which leads to melting, cavitation and formation of spallation liquid layer. The calculated asymptotic surface velocity of this layer as a function of fluence is in reasonably good agreement with experimental data.

  6. Protocols for dynamically probing topological edge states and dimerization with fermionic atoms in optical potentials

    Science.gov (United States)

    Metcalf, Mekena; Lai, Chen-Yen; Wright, Kevin; Chien, Chih-Chun

    2017-06-01

    Topological behavior has been observed in quantum systems including ultracold atoms. However, background harmonic traps for cold atoms hinder the direct detection of topological edge states arising at the boundary because the distortion fuses the edge states into the bulk. We propose experimentally feasible protocols to probe localized edge states and dimerization of ultracold fermions. By confining cold atoms in a ring lattice and changing the boundary condition from periodic to open using an off-resonant laser sheet to cut open the ring, topological edge states can be generated. A lattice in a topological configuration can trap a single particle released at the edge as the system evolves in time. Alternatively, depleting an initially filled lattice away from the boundary reveals the occupied edge states. Signatures of dimerization in the presence of contact interactions can be found in selected correlations as the system boundary suddenly changes from periodic to open and exhibit memory effects of the initial state distinguishing different configurations.

  7. Optical Probe of the Superconducting Normal Mixed State in a Magnetic Penetration Thermometer

    Science.gov (United States)

    Stevenson, T. R.; Balvin, M. A.; Bandler, S. R.; Denis, K. L.; Lee, S. -J.; Nagler, P. C.; Smith, S. J.

    2016-01-01

    Using ultraviolet photon pulses, we have probed the internal behavior of a molybdenum-gold Magnetic Penetration Thermometer (MPT) that we designed for x-ray microcalorimetry. In this low-temperature detector, the diamagnetic response of a superconducting MoAu bilayer is used to sense temperature changes in response to absorbed photons. We have previously described an approximate model that explains the high responsivity of the detector to temperature changes as a consequence of a Meissner transition of the molybdenum-gold film in the magnetic field applied by the superconducting circuit used to bias the detector. We compare measurements of MPT heat capacity and thermal conductance, derived from UV photon pulse data, to our model predictions for the thermodynamic properties of the sensor and for the electron cooling obtained by quasiparticle recombination. Our data on electron cooling power is also relevant to the operation of other superconducting detectors, such as Microwave Kinetic Inductance Detectors.

  8. Optical probing of mechanical loss of a Si_{3}N_{4} membrane below 100 mK

    CERN Document Server

    Fischer, R; Assumpção, G G T; Yu, P -L; Cicak, K; Peterson, R W; Simmonds, R W; Regal, C A

    2016-01-01

    We report on low mechanical loss in a high-stress silicon nitride (Si_{3}N_{4}) membrane at temperatures below 100 mK. We isolate a membrane via a phononic shield formed within a supporting silicon frame, and measure the mechanical quality factor of a number of high-tension membrane modes as we vary our dilution refrigerator base temperature between 35 mK and 5 K. At the lowest temperatures, we obtain a maximum quality factor (Q) of 2.3\\times10^{8}, corresponding to a Q-frequency product (QFP) of 3.7\\times10^{14} Hz. These measurements complement the recent observation of improved quality factors of Si_{3}N_{4} at ultralow temperatures via electrical detection. We also observe a dependence of the quality factor on optical heating of the device. By combining exceptional material properties, high tension, advanced isolation and clamping techniques, high-stress mechanical objects are poised to explore a new regime of exceptional quality factors. Such quality factors combined with an optical probe at cryogenic te...

  9. Volmer-Weber growth stages of polycrystalline metal films probed by in situ and real-time optical diagnostics

    Science.gov (United States)

    Abadias, G.; Simonot, L.; Colin, J. J.; Michel, A.; Camelio, S.; Babonneau, D.

    2015-11-01

    The Volmer-Weber growth of high-mobility metal films is associated with the development of a complex compressive-tensile-compressive stress behavior as the film deposition proceeds through nucleation of islands, coalescence, and formation of a continuous layer. The tensile force maximum has been attributed to the end of the islands coalescence stage, based on ex situ morphological observations. However, microstructural rearrangements are likely to occur in such films during post-deposition, somewhat biasing interpretations solely based on ex situ analysis. Here, by combining two simultaneous in situ and real-time optical sensing techniques, based on surface differential reflectance spectroscopy (SDRS) and change in wafer curvature probed by multibeam optical stress sensor (MOSS), we provide direct evidence that film continuity does coincide with tensile stress maximum during sputter deposition of a series of metal (Ag, Au, and Pd) films on amorphous SiOx. Stress relaxation after growth interruption was testified from MOSS, whose magnitude scaled with adatom mobility, while no change in SDRS signal could be revealed, ruling out possible changes of the surface roughness at the micron scale.

  10. Deep tissue volume imaging of birefringence through fibre-optic needle probes for the delineation of breast tumour

    Science.gov (United States)

    Villiger, Martin; Lorenser, Dirk; McLaughlin, Robert A.; Quirk, Bryden C.; Kirk, Rodney W.; Bouma, Brett E.; Sampson, David D.

    2016-07-01

    Identifying tumour margins during breast-conserving surgeries is a persistent challenge. We have previously developed miniature needle probes that could enable intraoperative volume imaging with optical coherence tomography. In many situations, however, scattering contrast alone is insufficient to clearly identify and delineate malignant regions. Additional polarization-sensitive measurements provide the means to assess birefringence, which is elevated in oriented collagen fibres and may offer an intrinsic biomarker to differentiate tumour from benign tissue. Here, we performed polarization-sensitive optical coherence tomography through miniature imaging needles and developed an algorithm to efficiently reconstruct images of the depth-resolved tissue birefringence free of artefacts. First ex vivo imaging of breast tumour samples revealed excellent contrast between lowly birefringent malignant regions, and stromal tissue, which is rich in oriented collagen and exhibits higher birefringence, as confirmed with co-located histology. The ability to clearly differentiate between tumour and uninvolved stroma based on intrinsic contrast could prove decisive for the intraoperative assessment of tumour margins.

  11. In vivo estimation of optical properties of rat liver using single-reflectance fiber probe during ischemia and reperfusion

    Science.gov (United States)

    Akter, Sharmin; Tanabe, Tomoki; Maejima, Satoshi; Kawauchi, Satoko; Sato, Shunichi; Hinoki, Akinari; Aosasa, Suefumi; Yamamoto, Junji; Nishidate, Izumi

    2016-04-01

    To quantify the changes in optical properties of in vivo rat liver tissue, we applied diffuse reflectance spectroscopy (DRS) system using single-reflectance fiber probe during ischemia and reperfusion evoked by hepatic portal occlusion (hepatic artery, portal vein and bile duct). Changes in the reduced scattering coefficient μ s', the absorption coefficient μ a, the tissue oxygen saturation StO2, and the oxidation of heme aa3 in cytochrome c oxidase (C cO) OHaa3 of in vivo rat liver (n = 6) were evaluated. Heme aa3 in C cO were significantly reduced (P ischemia, which indicates a sign of mitochondrial energy failure induced by oxygen insufficiency of liver tissue. We found that OHaa3 obtained from the proposed method was unchanged immediately after the onset of ischemia and started gradually decreasing at 2 min after the onset of ischemia. Difference in the time course between OHaa3 and the conventional ratio metric analysis with μ a(605)/ μ a(620) reported in literature demonstrates that the proposed method is effective in reduction of optical cross talk between hemoglobin and heme aa3. Our results suggest that DRS technique is applicable and useful for assessing in vivo tissue viability and hemodynamics in liver intraoperatively.

  12. Optical properties of single semiconductor nanowires and nanowire ensembles. Probing surface physics by photoluminescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pfueller, Carsten

    2011-06-27

    This thesis presents a detailed investigation of the optical properties of semiconductor nanowires (NWs) in general and single GaN NWs and GaN NW ensembles in particular by photoluminescence (PL) spectroscopy. NWs are often considered as potential building blocks for future nanometer-scaled devices. This vision is based on several attractive features that are generally ascribed to NWs. For instance, they are expected to grow virtually free of strain and defects even on substrates with a large structural mismatch. In the first part of the thesis, some of these expectations are examined using semiconductor NWs of different materials. On the basis of the temperature-dependent PL of Au- and selfassisted GaAs/(Al,Ga)As core-shell NWs, the influence of foreign catalyst particles on the optical properties of NWs is investigated. For the Au-assisted NWs, we find a thermally activated, nonradiative recombination channel, possibly related to Auatoms incorporated from the catalyst. These results indicate the limited suitability of catalyst-assisted NWs for optoelectronic applications. The effect of the substrate choice is studied by comparing the PL of ZnO NWs grown on Si, Al{sub 2}O{sub 3}, and ZnO substrates. Their virtually identical optical characteristics indicate that the synthesis of NWs may indeed overcome the constraints that limit the heteroepitaxial deposition of thin films. The major part of this thesis discusses the optical properties of GaN NWs grown on Si substrates. The investigation of the PL of single GaN NWs and GaN NW ensembles reveals the significance of their large surface-to-volume ratio. Differences in the recombination behavior of GaNNW ensembles and GaN layers are observed. First, the large surface-to-volume ratio is discussed to be responsible for the different recombination mechanisms apparent in NWs. Second, certain optical features are only found in the PL of GaN NWs, but not in that of GaN layers. An unexpected broadening of the donor

  13. Demonstration of a Fiber Optic Regression Probe in a High-Temperature Flow

    Science.gov (United States)

    Korman, Valentin; Polzin, Kurt

    2011-01-01

    The capability to provide localized, real-time monitoring of material regression rates in various applications has the potential to provide a new stream of data for development testing of various components and systems, as well as serving as a monitoring tool in flight applications. These applications include, but are not limited to, the regression of a combusting solid fuel surface, the ablation of the throat in a chemical rocket or the heat shield of an aeroshell, and the monitoring of erosion in long-life plasma thrusters. The rate of regression in the first application is very fast, while the second and third are increasingly slower. A recent fundamental sensor development effort has led to a novel regression, erosion, and ablation sensor technology (REAST). The REAST sensor allows for measurement of real-time surface erosion rates at a discrete surface location. The sensor is optical, using two different, co-located fiber-optics to perform the regression measurement. The disparate optical transmission properties of the two fiber-optics makes it possible to measure the regression rate by monitoring the relative light attenuation through the fibers. As the fibers regress along with the parent material in which they are embedded, the relative light intensities through the two fibers changes, providing a measure of the regression rate. The optical nature of the system makes it relatively easy to use in a variety of harsh, high temperature environments, and it is also unaffected by the presence of electric and magnetic fields. In addition, the sensor could be used to perform optical spectroscopy on the light emitted by a process and collected by fibers, giving localized measurements of various properties. The capability to perform an in-situ measurement of material regression rates is useful in addressing a variety of physical issues in various applications. An in-situ measurement allows for real-time data regarding the erosion rates, providing a quick method for

  14. A single-electron probe for buried optically active quantum dot

    Directory of Open Access Journals (Sweden)

    T. Nakaoka

    2012-09-01

    Full Text Available We present a simple method that enables both single electron transport through a self-assembled quantum dot and photon emission from the dot. The quantum dot buried in a semiconductor matrix is electrically connected with nanogap electrodes through tunneling junctions formed by a localized diffusion of the nanogap electrode metals. Coulomb blockade stability diagrams for the optically-active dot are clearly resolved at 4.2 K. The position of the quantum dot energy levels with respect to the contact Fermi level is controlled by the kind of metal atoms diffused from the nanogap electrodes.

  15. Optical probing of MgZnO/ZnO heterointerface confinement potential energy levels

    Energy Technology Data Exchange (ETDEWEB)

    Solovyev, V. V.; Van' kov, A. B.; Kukushkin, I. V. [Institute of Solid State Physics, RAS, Chernogolovka 142432 (Russian Federation); Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Falson, J.; Kozuka, Y. [Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); Zhang, D.; Smet, J. H. [Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Maryenko, D. [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Tsukazaki, A. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); PRESTO, Japan Science and Technology Agency (JST), Tokyo 102-0075 (Japan); Kawasaki, M. [Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan)

    2015-02-23

    Low-temperature photoluminescence and reflectance measurements were employed to study the optical transitions present in two-dimensional electron systems confined at Mg{sub x}Zn{sub 1–x}O/ZnO heterojunctions. Transitions involving A- and B-holes and electrons from the two lowest subbands formed within the confinement potential are detected. In the studied density range of 2.0–6.5 × 10{sup 11 }cm{sup −2}, the inter-subband splitting is measured and the first excited electron subband is shown to be empty of electrons.

  16. Nanoscale optical properties of metal nanoparticles probed by Second Harmonic Generation microscopy.

    Science.gov (United States)

    Shen, Hong; Nguyen, Ngoc; Gachet, David; Maillard, Vincent; Toury, Timothée; Brasselet, Sophie

    2013-05-20

    We report spatial and vectorial imaging of local fields' confinement properties in metal nanoparticles with branched shapes, using Second Harmonic Generation (SHG) microscopy. Taking advantage of the coherent nature of this nonlinear process, the technique provides a direct evidence of the coupling between the excitation polarization and both localization and polarization specificities of local fields at the sub-diffraction scale. These combined features, which are governed by the nanoparticles' symmetry, are not accessible using other contrasts such as linear optical techniques or two-photon luminescence.

  17. Design of a simple cryogenic system for ultraviolet-visible absorption spectroscopy with a back-reflectance fiber optic probe.

    Science.gov (United States)

    Vinyard, Andrew; Hansen, Kaj A; Byrd, Ross; Stuart, Douglas A; Hansen, John E

    2014-01-01

    We report a convenient and inexpensive technique for the rapid acquisition of absorption spectra from small samples at cryogenic temperatures using a home built cryostat with novel collection optics. A cylindrical copper block was constructed with a coaxial bore to hold a 4.00 mm diameter electron paramagnetic resonance (EPR) tube and mounted on a copper feed in thermal contact with liquid nitrogen. A 6.35 mm diameter hole was bored into the side of the cylinder so a fiber optic cable bundle could be positioned orthogonally to the EPR tube. The light passing through the sample is reflected off of the opposing surfaces of the EPR tube and surrounding copper, back through the sample. The emergent light is then collected using the fiber optic bundle and analyzed using a dispersive spectrometer. Absorption spectra for KMnO4 were measured between 400 and 700 nm. Absorption intensity at 506, 525, 545, and 567 nm was found to be proportional to concentration, displaying Beer's law-like behavior. The EPR tube had an internal diameter of 3.2 mm; the double pass of the probe beam through the sample affords a central path length of about 6.4 mm. Comparing these measurements with those recorded on a conventional tabletop spectrometer using a cuvette with a 10.00 mm path length, we consistently found a ratio between intensities of 0.58 rather than the anticipated 0.64. These 6% smaller values we attribute to the curvature of the EPR tube and transmission/reflection losses. This system is particularly well-suited to studying the kinetics and dynamics of chemical reactions at cryogenic temperatures. The rapid response (100 ms) and multiplex advantage provided the opportunity of recording simultaneous time courses at several wavelengths following initiation of a chemical reaction with a pulsed laser source.

  18. Laser-induced fluorescence fiber optic probe measurement of oil dilution by fuel

    Science.gov (United States)

    Parks, II, James E [Knoxville, TN; Partridge, Jr., William P [Oak Ridge, TN

    2010-11-23

    Apparatus for detecting fuel in oil includes an excitation light source in optical communication with an oil sample for exposing the oil sample to excitation light in order to excite the oil sample from a non-excited state to an excited state and a spectrally selective device in optical communication with the oil sample for detecting light emitted from the oil sample as the oil sample returns from the excited state to a non-excited state to produce spectral indicia that can be analyzed to determine the presence of fuel in the oil sample. A method of detecting fuel in oil includes the steps of exposing a oil sample to excitation light in order to excite the oil sample from a non-excited state to an excited state, as the oil sample returns from the excited state to a non-excited state, detecting light emitted from the oil sample to produce spectral indicia; and analyzing the spectral indicia to determine the presence of fuel in the oil sample.

  19. Probing the interaction between two microspheres in a single Gaussian beam optical trap

    Science.gov (United States)

    Parthasarathi, Praveen; Iyengar, Shruthi Subhash; Lakkegowda, Yogesha; Bhattacharya, Sarbari; Ananthamurthy, Sharath

    2016-09-01

    Interactions between trapped microspheres have been studied in two geometries so far: (i) using line optical tweezers and (ii) in traps using two counter propagating laser beams. In both trap geometries, the stable inter bead separations have been attributed to optical binding. One could also trap two such beads in a single beam Gaussian laser trap. While there are reports that address this configuration through theoretical or simulation based treatments, there has so far been no detailed experimental work that measures the interactions. In this work, we have recorded simultaneously the fluctuation spectra of two beads trapped along the laser propagation direction in a single Gaussian beam trap by measuring the back scattered signal from the trapping and a tracking laser beam that are counter propagating . The backscattering from the trapping laser monitors the bead encountered earlier in the propagation path. The counter propagating tracking laser, on the other hand, is used to monitor the fluctuations of the second bead. Detection is by using quadrant photo detectors placed at either end. The autocorrelation functions of both beads reveal marked departures from that obtained when there is only one bead in the trap. Moreover, the fall-off profiles of the autocorrelation indicates the presence of more than one relaxation time. This indicates a method of detecting the presence of a second bead in a trap without directly carrying out measurements on it. Further, a careful analysis of the relaxation times could also reveal the nature of interactions between the beads.

  20. Nanoengineering of optical probes for in situ nanomechanical studies and biological interrogation (Conference Presentation)

    Science.gov (United States)

    Sirbuly, Donald J.; Huang, Qian; Villanueva, Josh

    2016-09-01

    The ability to stimulate, track, and record biological processes with as many data channels as possible is central to decoding complex phenomena in the body. For example, many biological processes involve small mechanical cues that can help drive chemical reactions and/or initiate responses to external stimuli. However, to measure these nanomechanical events, specialized tools are required that can not only achieve piconewton force resolution, but be able to record from multiple sites while maintaining a small footprint to allow embedded or intracellular measurements. This is challenging for state-of-the-art instruments such as atomic force microscopes or optical traps due to the difficulty in multiplexing, their size, and feedback mechanisms. Here we describe a new nanofiber-optic platform that can detect sub-piconewton forces by monitoring far-field scattering signals of plasmonic nanoparticles moving within the near-field. To provide mechanical resistance to the nanoparticles, and allow quantitative forces to be extracted, compressible polymer claddings have been designed that have tunable spring constants and chemical compositions. The transduction mechanism is demonstrated both on detecting local contact forces acting on the nanoparticles as well as acoustic waves propagating in the medium. Because of the small cross-sectional areas ( 1 mm), these nanofibers can also be inserted deep into tissue to locally excite and collect signals from single cells (e.g., neurons) with minimal invasiveness. Experiments focused on stimulating and recording from brain tissue will be discussed.

  1. Probing mechanical properties of Jurkat cells under the effect of ART using oscillating optical tweezers.

    Directory of Open Access Journals (Sweden)

    Samaneh Khakshour

    Full Text Available Acute lymphoid leukemia is a common type of blood cancer and chemotherapy is the initial treatment of choice. Quantifying the effect of a chemotherapeutic drug at the cellular level plays an important role in the process of the treatment. In this study, an oscillating optical tweezer was employed to characterize the frequency-dependent mechanical properties of Jurkat cells exposed to the chemotherapeutic agent, artesunate (ART. A motion equation for a bead bound to a cell was applied to describe the mechanical characteristics of the cell cytoskeleton. By comparing between the modeling results and experimental results from the optical tweezer, the stiffness and viscosity of the Jurkat cells before and after the ART treatment were obtained. The results demonstrate a weak power-law dependency of cell stiffness with frequency. Furthermore, the stiffness and viscosity were increased after the treatment. Therefore, the cytoskeleton cell stiffness as the well as power-law coefficient can provide a useful insight into the chemo-mechanical relationship of drug treated cancer cells and may serve as another tool for evaluating therapeutic performance quantitatively.

  2. Probing focal cortical dysplasia in formalin fixed samples using tissue optical spectroscopy

    Science.gov (United States)

    Anand, Suresh; Cicchi, Riccardo; Giordano, Flavio; Buccoliero, Anna Maria; Conti, Valerio; Guerrini, Renzo; Pavone, Francesco Saverio

    2016-03-01

    Focal cortical dysplasia (FCD) is one of most common causes of intractable epilepsy in pediatric population and these are often insensitive to anti-epileptic drugs. FCD is characterized by a disarray in localized regions of the cerebral cortex and abnormal neurons which results them to misfire with incorrect signals. Resective neurosurgery to remove or disconnect the affected parts from the rest of the brain seems to be a viable option to treat FCD. Before neurosurgery the subject could undergo imaging studies including magnetic resonance imaging (MRI) or computed tomography (CT) scans. On the downside FCD could be elusive in MRI images and may be practically invisible in CT scans. Furthermore, unnecessary removal of normal tissues is to be taken into consideration as this could lead to neurological defects. In this context, optical spectroscopy have been widely investigated as an alternative technique for the detection of abnormal tissues in different organ sites. Disease progression is accompanied by a number of architectural, biochemical and morphological changes. These variations are reflected in the spectral intensity and line shape. Here, in this proof of concept study we propose to investigate the application of tissue optical spectroscopy based on fluorescence excitation at two wavelength 378 and 445 nm coupled along with Raman spectroscopy for the detection of FCD on formalin fixed tissue specimens from pediatric subjects. For fluorescence at both the excitation wavelengths FCD showed a decreased intensity at longer wavelength when compared to normal tissues. Also, differences exist in the Raman spectral profiles of normal and FCD.

  3. Inelastic light scattering to probe strongly correlated bosons in optical lattices

    Energy Technology Data Exchange (ETDEWEB)

    Fort, Chiara; Fabbri, Nicole; Fallani, Leonardo; Clement, David; Inguscio, Massimo, E-mail: fort@lens.unifi.it [European Laboratory for Nonlinear Spectroscopy (LENS), via Nello Carrara 1, 50019 Sesto Fiorentino (Italy)

    2011-01-10

    We have used inelastic light scattering to study correlated phases of an array of one-dimensional interacting Bose gases. In the linear response regime, the observed spectra are proportional to the dynamic structure factor. In particular we have investigated the superfluid to Mott insulator crossover loading the one-dimensional gases in an optical lattice and monitoring the appearance of an energy gap due to finite particle-hole excitation energy. We attribute the low frequency side of the spectra to the presence of some superfluid and normal phase fraction between the Mott insulator regions with different fillings produced in the inhomogeneous systems. In the Mott phase we also investigated excitations to higher excited bands of the optical lattice, the spectra obtained in this case being connected to the single particle spectral function. In one-dimensional systems the effect of thermal fluctuations and interactions is enhanced by the reduced dimensionality showing up in the dynamic structure factor. We measured the dynamic structure factor of an array of one-dimensional bosonic gases pointing out the effect of temperature-induced phase fluctuations in reducing the coherence length of the system.

  4. Human oral mucosa tissue-engineered constructs monitored by Raman fiber-optic probe.

    Science.gov (United States)

    Khmaladze, Alexander; Kuo, Shiuhyang; Kim, Roderick Y; Matthews, Robert V; Marcelo, Cynthia L; Feinberg, Stephen E; Morris, Michael D

    2015-01-01

    In maxillofacial and oral surgery, there is a need for the development of tissue-engineered constructs. They are used for reconstructions due to trauma, dental implants, congenital defects, or oral cancer. A noninvasive monitoring of the fabrication of tissue-engineered constructs at the production and implantation stages done in real time is extremely important for predicting the success of tissue-engineered grafts. We demonstrated a Raman spectroscopic probe system, its design and application, for real-time ex vivo produced oral mucosa equivalent (EVPOME) constructs noninvasive monitoring. We performed in vivo studies to find Raman spectroscopic indicators for postimplanted EVPOME failure and determined that Raman spectra of EVPOMEs preexposed to thermal stress during manufacturing procedures displayed correlation of the band height ratio of CH2 deformation to phenylalanine ring breathing modes, giving a Raman metric to distinguish between healthy and compromised postimplanted constructs. This study is the step toward our ultimate goal to develop a stand-alone system, to be used in a clinical setting, where the data collection and analysis are conducted on the basis of these spectroscopic indicators with minimal user intervention.

  5. Error reduction in three-dimensional metrology combining optical and touch probe data

    Science.gov (United States)

    Gerde, Janice R.; Christens-Barry, William A.

    2010-08-01

    Analysis of footwear under the Harmonized Tariff Schedule of the United States (HTSUS) is partly based on identifying the boundary ("parting line") between the "external surface area upper" (ESAU) and the sample's sole. Often, that boundary is obscured. We establish the parting line as the curved intersection between the sample outer surface and its insole surface. The outer surface is determined by discrete point cloud coordinates obtained using a laser scanner. The insole surface is defined by point cloud data, obtained using a touch probe device-a coordinate measuring machine (CMM). Because these point cloud data sets do not overlap spatially, a polynomial surface is fitted to the insole data and extended to intersect a mesh fitted to the outer surface point cloud. This line of intersection defines the ESAU boundary, permitting further fractional area calculations to proceed. The defined parting line location is sensitive to the polynomial used to fit experimental data. Extrapolation to the intersection with the ESAU can heighten this sensitivity. We discuss a methodology for transforming these data into a common reference frame. Three scenarios are considered: measurement error in point cloud coordinates, from fitting a polynomial surface to a point cloud then extrapolating beyond the data set, and error from reference frame transformation. These error sources can influence calculated surface areas. We describe experiments to assess error magnitude, the sensitivity of calculated results on these errors, and minimizing error impact on calculated quantities. Ultimately, we must ensure that statistical error from these procedures is minimized and within acceptance criteria.

  6. Probing intensity limits of LHC-Type bunches in CERN SPS with nominal optics

    CERN Document Server

    Adrian, G; Andujar, O; Argyropoulos, T; Axensalva, J; Baldy, J; Bartosik, H; Cettour Cave, S; Chapuis, F; Comblin, JF; Cornelis, K; Cotte, D; Cunnington, K; Damerau, H; Delrieux, M; Duran-Lopez, JL; Esteban Mueller, J; Findlay, A; Fleuret, J; Follin, F; Freyermuth, P; Genoud, H; Gilardoni, S; Guerrero, A; Hancock, S; Hanke, K; Hans, O; Hazelaar, R; Höfle, W; Jensen, L; Kuczerowski, J; Le Borgne, Y; Maillet, R; Manglunki, D; Massot, S; Matli, E; Métral, G; Métral, E; Mikulec, B; Nonglaton, JM; Ovalle, E; Papaphilippou, Y; Pereira, L; Peters, F; Rey, A; Ridewood, J; Rumolo, G; Salvant, B; Sanchez Alvarez, JL; Shaposhnikova, E; Steerenberg, R; Steinhagen, R; Tan, J; Vandorpe, B; Veyrunes, E

    2011-01-01

    Some of the upgrade scenarios of the high-luminosity LHC require large intensity per bunch from the injector chain. Single bunch beams with intensities of up to 3.5 to 4e11 p/b and nominal emittances were successfully produced in the PS Complex and delivered to the SPS in 2010. This contribution presents results of studies with this new intense beam in the SPS to probe single bunch intensity limitations with nominal gamma transition. In particular, the vertical Transverse Mode Coupling Instability (TMCI) threshold with low chromaticity was observed at 1.6e11 p/b for single nominal LHC bunches in the SPS. With increased vertical chromaticity, larger intensities could be injected, stored along the flat bottom and accelerated up to 450 GeV/c. However, significant losses and/or transverse emittance blow up were then observed. Longitudinal and transverse optimization efforts in the PSB, PS and SPS were put in place to minimize this beam degradation and succeeded to obtain single 2.5e11 p/b LHC type bunches with sa...

  7. Preparation and characterization of a magnetic and optical dual-modality molecular probe

    Energy Technology Data Exchange (ETDEWEB)

    Bumb, A; Brechbiel, M W [Radioimmune and Inorganic Chemistry Section, Radiation Oncology Branch, NCI, NIH, Building 10, Room 1B53, 10 Center Drive, Bethesda, MD 20892 (United States); Regino, C A S; Ogawa, M; Choyke, P L [Molecular Imaging Program, NCI, NIH, Building 10, Room B3B69, 10 Center Drive, Bethesda, MD 20892 (United States); Perkins, M R [Vaccine Research Center, NIAID, NIH, Building 40, Room 3608B, 40 Convent Drive, Bethesda, MD 20892 (United States); Bernardo, M [SAIC-Frederick Inc., NCI-Frederick, Frederick, MD 21702 (United States); Fugger, L [MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, The University of Oxford, Oxford OX3 9DS (United Kingdom); Dobson, P J, E-mail: Bumba@mail.nih.gov, E-mail: martinwb@mail.nih.gov [Oxford University Begbroke Science Park, Sandy Lane, Kidlington, Oxon OX5 1PF (United Kingdom)

    2010-04-30

    Multi-modality imaging probes combine the advantages of individual imaging techniques to yield highly detailed anatomic and molecular information in living organisms. Herein, we report the synthesis and characterization of a dual-modality nanoprobe that couples the magnetic properties of ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) with the near infrared fluorescence of Cy5.5. The fluorophore is encapsulated in a biocompatible shell of silica surrounding the iron oxide core for a final diameter of {approx} 17 nm. This silica-coated iron oxide nanoparticle (SCION) has been analyzed by transmission electron microscopy, dynamic light scattering, and superconducting quantum interference device (SQUID). The particle demonstrates a strong negative surface charge and maintains colloidal stability in the physiological pH range. Magnetic hysteresis analysis confirms superparamagnetic properties that could be manipulated for thermotherapy. The viability of primary human monocytes, T cells, and B cells incubated with the particle has been examined in vitro. In vivo analysis of agent leakage into subcutaneous A431 tumors in mice was also conducted. This particle has been designed for diagnostic application with magnetic resonance and fluorescence imaging, and has future potential to serve as a heat-sensitive targeted drug delivery platform.

  8. Reconstruction methods for acoustic particle detection in the deep sea using clusters of hydrophones

    CERN Document Server

    Richardt, C; Graf, K; Hoessl, J; Kappes, A; Katz, U; Lahmann, R; Naumann, Ch; Neff, M; Schoeck, F; 10.1016/j.astropartphys.2008.11.003

    2009-01-01

    This article focuses on techniques for acoustic noise reduction, signal filters and source reconstruction. For noise reduction, bandpass filters and cross correlations are found to be efficient and fast ways to improve the signal to noise ratio and identify a possible neutrino-induced acoustic signal. The reconstruction of the position of an acoustic point source in the sea is performed by using small-volume clusters of hydrophones (about 1 cubic meter) for direction reconstruction by a beamforming algorithm. The directional information from a number of such clusters allows for position reconstruction. The algorithms for data filtering, direction and position reconstruction are explained and demonstrated using simulated data.

  9. Optical techniques for nanoscale probing and chemical detection in aqueous environments

    Science.gov (United States)

    Pristinski, Denis

    We present an investigation of charge-dependent physical properties of water-soluble synthetic polymers and polymer-based layered structures, using optical detection methods in a visible range. We apply in situ nanoscale optical techniques to study response of polymer systems to changes in pH, polymer concentration, and concentration and type of counterions. This work describes three optical techniques and custom built instrumental setups for nanoscale polymer characterization in aqueous environment. Phase-modulated ellipsometry was applied to determine the refraction coefficient and the thickness of a hydrogel-like polymer layer on a substrate. The present study describes the sensitivity of the phase modulated ellipsometry to errors of measurement and determines conditions for decoupling film thickness and refraction index. It is shown that, for a certain range of film thickness, both the thickness and the refractive index can be determined from a single measurement with high precision. This optimal range of the film thickness is calculated for organic thin films, and the analysis is tested on crosslinked poly(methacrylic acid) polymer films in air and in water. Fluorescent correlation spectroscopy was used to investigate diffusion of a synthetic polyelectrolyte in aqueous solutions. Translational diffusion of Alexa-labeled poly(methacrylic acid) chains was studied in very dilute, 10-4 mg/ml, solutions as a function of polymer charge density and counterion concentration. The results illustrate the utility of the technique for studying hydrodynamic sizes of polyelectrolyte coils in response to variation in solution pH or concentration of salt and polyelectrolytes. We apply surface-enhanced Raman scattering (SERS) for studying of enhancement capabilities of individual silver nanoparticles attached to glass and silicon substrates. Nanoparticles were electrostatically bound to a self-assembled polyallylamine hydrochloride (PAH) monolayer, which was deposited on

  10. Surface-enhanced Raman scattering: a new optical probe in molecular biophysics and biomedicine

    DEFF Research Database (Denmark)

    Kneipp, J.; Wittig, B.; Bohr, Henrik

    2010-01-01

    Sensitive and detailed molecular structural information plays an increasing role in molecular biophysics and molecular medicine. Therefore, vibrational spectroscopic techniques, such as Raman scattering, which provide high structural information content are of growing interest in biophysical...... of the free electrons in the metal. This effect of surface-enhanced Raman scattering (SERS) allows us to push vibrational spectroscopy to new limits in detection sensitivity, lateral resolution, and molecular structural selectivity. This opens up exciting perspectives also in molecular biospectroscopy...... and biomedical research. Raman spectroscopy can be revolutionized when the inelastic scattering process takes place in the very close vicinity of metal nanostructures. Under these conditions, strongly increased Raman signals can be obtained due to resonances between optical fields and the collective oscillations...

  11. Optical probing of Eu ions confined in an RF trap

    Indian Academy of Sciences (India)

    Pushpa M Rao; Anita Gupta

    2012-01-01

    The Eu ions confined in an RF quadrupole trap, has been optically detected. Using a tunable dye laser which is pumped by a Nd-YAG pulsed laser system, the resonance ${}^9S_4–6 p_{3/2}$, = 5 transition of the Eu ions have been excited and the resulting fluorescence to the metastable ${}^9 D_{4−6}$ state has been detected. In preparation to determine the ground-state hyperfine splitting of the odd isotopes we found the optimum trapping operating point. We have also observed a number of instabilities inside the region of the stability for an ideal trap. These non-linear resonances arise from higher-order contributions to the ideal quadrupole potential.

  12. Probing the Spin-Polarized Electronic Band Structure in Monolayer Transition Metal Dichalcogenides by Optical Spectroscopy

    Science.gov (United States)

    Wang, Zefang; Zhao, Liang; Mak, Kin Fai; Shan, Jie

    2017-02-01

    We study the electronic band structure in the K/K' valleys of the Brillouin zone of monolayer WSe2 and MoSe2 by optical reflection and photoluminescence spectroscopy on dual-gated field-effect devices. Our experiment reveals the distinct spin polarization in the conduction bands of these compounds by a systematic study of the doping dependence of the A and B excitonic resonances. Electrons in the highest-energy valence band and the lowest-energy conduction band have antiparallel spins in monolayer WSe2, and parallel spins in monolayer MoSe2. The spin splitting is determined to be hundreds of meV for the valence bands and tens of meV for the conduction bands, which are in good agreement with first principles calculations. These values also suggest that both n- and p-type WSe2 and MoSe2 can be relevant for spin- and valley-based applications

  13. Full-angle optical imaging of near-infrared fluorescent probes implanted in small animals

    Institute of Scientific and Technical Information of China (English)

    Gang Hu; Junjie Yao; Jing Bai

    2008-01-01

    To provide a valuable experimental platform for in vivo biomedical research of small animal model with fluorescence mediated approach, we developed a whole-body near-infrared fluorescence molecular imaging system as described in this paper. This system is based on a sensitive CCD camera and has the ability to achieve 360° full-angle source illuminations and projections capture of the targets to obtain the dense sampling by performing rotational scan. The measurement accuracy is validated from cylinder phantom experiments by the comparison between the experimental data and theoretical predictions. Finally, we also present typical in vivo images of fluorescent tube implanted into the mouse body. The results are promising and have proved the system imaging performance for macroscopic optical biomedical research.

  14. A microfluidic platform for probing single cell plasma membranes using optically trapped Smart Droplet Microtools (SDMs).

    Science.gov (United States)

    Lanigan, Peter M P; Ninkovic, Tanja; Chan, Karen; de Mello, Andrew J; Willison, Keith R; Klug, David R; Templer, Richard H; Neil, Mark A A; Ces, Oscar

    2009-04-21

    We recently introduced a novel platform based upon optically trapped lipid coated oil droplets (Smart Droplet Microtools-SDMs) that were able to form membrane tethers upon fusion with the plasma membrane of single cells. Material transfer from the plasma membrane to the droplet via the tether was seen to occur. Here we present a customised version of the SDM approach based upon detergent coated droplets deployed within a microfluidic format. These droplets are able to differentially solubilise the plasma membrane of single cells with spatial selectivity and without forming membrane tethers. The microfluidic format facilitates separation of the target cells from the bulk SDM population and from downstream analysis modules. Material transfer from the cell to the SDM was monitored by tracking membrane localized EGFP.

  15. Measurement of Wave Electric Fields in Plasmas by Electro-Optic Probe

    CERN Document Server

    Nishiura, M; Mushiake, T; Kawazura, Y; Osawa, R; Fujinami, K; Yano, Y; Saitoh, H; Yamasaki, M; Kashyap, A; Takahashi, N; Nakatsuka, M; Fukuyama, A

    2016-01-01

    Electric field measurement in plasmas permits quantitative comparison between the experiment and the simulation in this study. An electro-optic (EO) sensor based on Pockels effect is demonstrated to measure wave electric fields in the laboratory magnetosphere of the RT-1 device with high frequency heating sources. This system gives the merits that electric field measurements can detect electrostatic waves separated clearly from wave magnetic fields, and that the sensor head is separated electrically from strong stray fields in circumference. The electromagnetic waves are excited at the double loop antenna for ion heating in electron cyclotron heated plasmas. In the air, the measured wave electric fields are in good absolute agreement with those predicted by the TASK/WF2 code. In inhomogeneous plasmas, the wave electric fields in the peripheral region are enhanced compared with the simulated electric fields. The potential oscillation of the antenna is one of the possible reason to explain the experimental resu...

  16. Optical Aptamer Probes of Fluorescent Imaging to Rapid Monitoring of Circulating Tumor Cell

    Directory of Open Access Journals (Sweden)

    Ji Yeon Hwang

    2016-11-01

    Full Text Available Fluorescence detecting of exogenous EpCAM (epithelial cell adhesion molecule or muc1 (mucin1 expression correlated to cancer metastasis using nanoparticles provides pivotal information on CTC (circulating tumor cell occurrence in a noninvasive tool. In this study, we study a new skill to detect extracellular EpCAM/muc1 using quantum dot-based aptamer beacon (QD-EpCAM/muc1 ALB (aptamer linker beacon. The QD-EpCAM/muc1 ALB was designed using QDs (quantum dots and probe. The EpCAM/muc1-targeting aptamer contains a Ep-CAM/muc1 binding sequence and BHQ1 (black hole quencher 1 or BHQ2 (black hole quencher2. In the absence of target EpCAM/muc1, the QD-EpCAM/muc1 ALB forms a partial duplex loop-like aptamer beacon and remained in quenched state because the BHQ1/2 quenches the fluorescence signal-on of the QD-EpCAM/muc1 ALB. The binding of EpCAM/muc1 of CTC to the EpCAM/muc1 binding aptamer sequence of the EpCAM/muc1-targeting oligonucleotide triggered the dissociation of the BHQ1/2 quencher and subsequent signal-on of a green/red fluorescence signal. Furthermore, acute inflammation was stimulated by trigger such as caerulein in vivo, which resulted in increased fluorescent signal of the cy5.5-EpCAM/muc1 ALB during cancer metastasis due to exogenous expression of EpCAM/muc1 in Panc02-implanted mouse model.

  17. Optical afterburner for an x-ray free electron laser as a tool for pump-probe experiments

    Directory of Open Access Journals (Sweden)

    E. L. Saldin

    2010-03-01

    Full Text Available We propose a new scheme for two-color operation of an x-ray self-amplified spontaneous emission free electron laser (SASE FEL. The scheme is based on an intrinsic feature of such a device: chaotic modulations of electron beam energy and energy spread on the scale of FEL coherence length are converted into large density modulations on the same scale with the help of a dispersion section, installed behind the x-ray undulator. Powerful radiation is then generated with the help of a dedicated radiator (like an undulator that selects a narrow spectral line, or one can simply use, for instance, broadband edge radiation. A typical radiation wavelength can be as short as a FEL coherence length, and can be redshifted by increasing the dispersion section strength. In practice it means the wavelength ranges from vacuum ultraviolet to infrared. The long-wavelength radiation pulse is naturally synchronized with the x-ray pulse and can be either directly used in pump-probe experiments or cross correlated with a high-power pulse from a conventional laser system. In this way experimenters overcome jitter problems and can perform pump-probe experiments with femtosecond resolution. Additional possibilities like on-line monitoring of x-ray pulse duration (making “optical replica” of an x-ray pulse are also discussed in the paper. The proposed scheme is very simple, cheap, and robust, and therefore can be easily realized in facilities like FLASH, European XFEL, LCLS, and SCSS.

  18. Mapping Sentinel Lymph Node Metastasis by Dual-probe Optical Imaging

    Science.gov (United States)

    Yang, Xiangyu; Wang, Zhe; Zhang, Fuwu; Zhu, Guizhi; Song, Jibin; Teng, Gao-Jun; Niu, Gang; Chen, Xiaoyuan

    2017-01-01

    Purpose: Sentinel lymph node biopsy (SLNB) has emerged as the preferred standard procedure in patients with breast cancer, melanoma and other types of cancer. Herein, we developed a method to intra-operatively map SLNs and differentiate tumor metastases within SLNs at the same time, with the aim to provide more accurate and real-time intraoperative guidance. Experimental Design: Hyaluronic acid (HA), a ligand of lymphatic vessel endothelial hyaluronan receptor (LYVE)-1, is employed as a SLN mapping agent after being conjugated with a near-infrared fluorophore (Cy5.5). Different sized HAs (5, 10 and 20K) were tested in normal mice and mice with localized inflammation to optimize LN retention time and signal to background ratio. Cetuximab, an antibody against epidermal growth factor receptor (EGFR), and trastuzumab, an antibody against human epidermal growth factor receptor 2 (HER2), were labeled with near-infrared fluorophore (IRDye800) for detecting metastatic tumors. LN metastasis model was developed by hock injection of firefly luciferase engineered human head neck squamous carcinoma cancer UM-SCC-22B cells or human ovarian cancer SKOV-3 cells. The metastases within LNs were confirmed by bioluminescence imaging (BLI). IRDye800-Antibodies were intravenously administered 24 h before local administration of Cy5.5-HA. Optical imaging was then performed to identify nodal metastases. Results: Binding of HA with LYVE-1 was confirmed by ELISA and fluorescence staining. HA with a size of 10K was chosen based on the favorable migration and retention profile. After sequential administration of IRDye800-antibodies intravenously and Cy5.5-HA locally to a mouse model with LN metastases and fluorescence optical imaging, partially metastasized LNs were successfully distinguished from un-metastasized LNs and fully tumor occupied LNs, based on the different signal patterns. Conclusions: Fluorophore conjugated HA is a potential lymphatic mapping agent for SLNB. Dual-tracer imaging

  19. Development and Beam-Shape Analysis of an Integrated Fiber-Optic Confocal Probe for High-Precision Central Thickness Measurement of Small-Radius Lenses

    Directory of Open Access Journals (Sweden)

    Boonsong Sutapun

    2015-04-01

    Full Text Available This work describes a new design of a fiber-optic confocal probe suitable for measuring the central thicknesses of small-radius optical lenses or similar objects. The proposed confocal probe utilizes an integrated camera that functions as a shape-encoded position-sensing device. The confocal signal for thickness measurement and beam-shape data for off-axis measurement can be simultaneously acquired using the proposed probe. Placing the probe’s focal point off-center relative to a sample’s vertex produces a non-circular image at the camera’s image plane that closely resembles an ellipse for small displacements. We were able to precisely position the confocal probe’s focal point relative to the vertex point of a ball lens with a radius of 2.5 mm, with a lateral resolution of 1.2 µm. The reflected beam shape based on partial blocking by an aperture was analyzed and verified experimentally. The proposed confocal probe offers a low-cost, high-precision technique, an alternative to a high-cost three-dimensional surface profiler, for tight quality control of small optical lenses during the manufacturing process.

  20. Optical spectroscopy of rare earth-doped oxyfluoro-tellurite glasses to probe local environment

    Indian Academy of Sciences (India)

    GAJANAN V HONNAVAR; K P RAMESH

    2017-09-01

    TeO$_2$-based glasses with a general formula 65TeO$_2$−5BaF$_2$−30ZnF$_2$ (TBZ) (in mol%) were prepared by usual melt quenching technique. Three mol% of europium (Eu) or erbium (Er) were added to the prepared glass at the expense of TeO$_2$. Raman, photoluminescence (PL), UV–visible absorption studies were carried out on the glass samples. Raman spectra of the undoped and doped glasses were analysed using the peak shift and the intensity variation along with fullwidth at half-maximum (FWHM). It was found that Eu-doped TBZ glass has a greater tendency towards depolymerizing theglass matrix by influencing the conversion of TeO$_4$ to TeO$_3$ units compared to Er-doped and undoped glasses. PL spectraof the glass samples show emission due to different possible transitions. Position of the peak of the de-convoluted spectrashows the position of the particular Stark component and the FWHM is a measure of the inhomogeneous broadening. TheUV–visible absorption spectra are used to calculate the optical density and to determine the band edge of the glass samplesby fitting to the Mott equation. It is seen that Eu-doped TBZ glass has a lesser bandgap than that of Er-doped glass.

  1. Probing the dynamics of an optically trapped particle by phase sensitive back focal plane interferometry

    CERN Document Server

    Roy, Basudev; Haldar, Arijit; Gupta, Ratnesh Kumar; Ghosh, Nirmalya; Banerjee, Ayan

    2012-01-01

    The dynamics of an optically trapped particle are often determined by measuring intensity shifts of the back-scattered light from the particle using position sensitive detectors. We present a technique which measures the phase of the back-scattered light using balanced detection in an external Mach-Zender interferometer scheme where we separate out and beat the scattered light from the bead and that from the top surface of our trapping chamber. The technique has improved axial motion resolution over intensity-based detection, and can also be used to measure lateral motion of the trapped particle. In addition, we are able to track the Brownian motion of trapped 1 and 3 $\\mu$m diameter beads from the phase jitter and show that, similar to intensity-based measurements, phase measurements can also be used to simultaneously determine displacements of the trapped bead as well as the spring constant of the trap. For lateral displacements, we have matched our experimental results with a simulation of the overall phas...

  2. Acceptor levels in ZnMgO:N probed by deep level optical spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kurtz, A.; Hierro, A., E-mail: adrian.hierro@upm.es; Muñoz, E. [ISOM and Dpto. Ingeniería Electrónica, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Mohanta, S. K.; Nakamura, A.; Temmyo, J. [Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan)

    2014-02-24

    A combination of deep level optical spectroscopy and lighted capacitance voltage profiling has been used to analyze the effect of N into the energy levels close to the valence band of Zn{sub 0.9}Mg{sub 0.1}O. Three energy levels at E{sub V} + 0.47 eV, E{sub V} + 0.35 eV, and E{sub V} + 0.16 eV are observed in all films with concentrations in the range of 10{sup 15}–10{sup 18} cm{sup −3}. The two shallowest traps at E{sub V} + 0.35 eV and E{sub V} + 0.16 eV have very large concentrations that scale with the N exposure and are thus potential acceptor levels. In order to correctly quantify the deep level concentrations, a metal-insulator-semiconductor model has been invoked, explaining well the resulting capacitance-voltage curves.

  3. [INVITED] Non-intrusive optical imaging of face to probe physiological traits in Autism Spectrum Disorder

    Science.gov (United States)

    Samad, Manar D.; Bobzien, Jonna L.; Harrington, John W.; Iftekharuddin, Khan M.

    2016-03-01

    Autism Spectrum Disorders (ASD) can impair non-verbal communication including the variety and extent of facial expressions in social and interpersonal communication. These impairments may appear as differential traits in the physiology of facial muscles of an individual with ASD when compared to a typically developing individual. The differential traits in the facial expressions as shown by facial muscle-specific changes (also known as 'facial oddity' for subjects with ASD) may be measured visually. However, this mode of measurement may not discern the subtlety in facial oddity distinctive to ASD. Earlier studies have used intrusive electrophysiological sensors on the facial skin to gauge facial muscle actions from quantitative physiological data. This study demonstrates, for the first time in the literature, novel quantitative measures for facial oddity recognition using non-intrusive facial imaging sensors such as video and 3D optical cameras. An Institutional Review Board (IRB) approved that pilot study has been conducted on a group of individuals consisting of eight participants with ASD and eight typically developing participants in a control group to capture their facial images in response to visual stimuli. The proposed computational techniques and statistical analyses reveal higher mean of actions in the facial muscles of the ASD group versus the control group. The facial muscle-specific evaluation reveals intense yet asymmetric facial responses as facial oddity in participants with ASD. This finding about the facial oddity may objectively define measurable differential markers in the facial expressions of individuals with ASD.

  4. Probing biological nanotopology via diffusion of weakly constrained plasmonic nanorods with optical coherence tomography.

    Science.gov (United States)

    Chhetri, Raghav K; Blackmon, Richard L; Wu, Wei-Chen; Hill, David B; Button, Brian; Casbas-Hernandez, Patricia; Troester, Melissa A; Tracy, Joseph B; Oldenburg, Amy L

    2014-10-14

    Biological materials exhibit complex nanotopology, i.e., a composite liquid and solid phase structure that is heterogeneous on the nanoscale. The diffusion of nanoparticles in nanotopological environments can elucidate biophysical changes associated with pathogenesis and disease progression. However, there is a lack of methods that characterize nanoprobe diffusion and translate easily to in vivo studies. Here, we demonstrate a method based on optical coherence tomography (OCT) to depth-resolve diffusion of plasmon-resonant gold nanorods (GNRs) that are weakly constrained by the biological tissue. By using GNRs that are on the size scale of the polymeric mesh, their Brownian motion is minimally hindered by intermittent collisions with local macromolecules. OCT depth-resolves the particle-averaged translational diffusion coefficient (DT) of GNRs within each coherence volume, which is separable from the nonequilibrium motile activities of cells based on the unique polarized light-scattering properties of GNRs. We show how this enables minimally invasive imaging and monitoring of nanotopological changes in a variety of biological models, including extracellular matrix (ECM) remodeling as relevant to carcinogenesis, and dehydration of pulmonary mucus as relevant to cystic fibrosis. In 3D ECM models, DT of GNRs decreases with both increasing collagen concentration and cell density. Similarly, DT of GNRs is sensitive to human bronchial-epithelial mucus concentration over a physiologically relevant range. This novel method comprises a broad-based platform for studying heterogeneous nanotopology, as distinct from bulk viscoelasticity, in biological milieu.

  5. Probing insect backscatter cross section and melanization using kHz optical remote detection system

    Science.gov (United States)

    Gebru, Alem; Brydegaard, Mikkel; Rohwer, Erich; Neethling, Pieter

    2017-01-01

    A kHz optical remote sensing system is implemented to determine insect melanization features. This is done by measuring the backscatter signal in the visible and near-infrared (VIS-NIR) and short-wave infrared (SWIR) in situ. It is shown that backscatter cross section in the SWIR is insensitive to melanization and absolute melanization can be derived from the ratio of backscatter cross section of different bands (SWIR/VIS-NIR). We have shown that reflectance from insect is stronger in the SWIR as compared to NIR and VIS. This reveals that melanization plays a big role to determine backscatter cross section. One can use this feature as a tool to improve insect species and age classification. To support the findings, we illustrated melanization feature using three different insects [dead, dried specimens of snow white moth (Spilosoma genus), fox moth (Macrothylacia), and leather beetle (Odontotaenius genus)]. It is shown that reflectance from the leather beetle in the VIS and NIR is more affected by melanization as compared with snow white moth.

  6. Optical Probes of MEH-PPV films at High Hydrostatic Pressure

    Science.gov (United States)

    Olejnik, E.; Singh, S.; Pandit, B.; Morandi, V.; Holt, J.; Sheng, C.-X.; Vardeny, Z. V.

    2010-03-01

    We investigate the primary and long-lived photoexcitations in π-conjugated polymer films with increased interchain coupling by studying the photophysics of substituted PPV derivative thin films, namely 2-methoxy-5-(2'-ethylhexyloxy) [MEH-PPV] at high hydrostatic pressure, P up to 120 kbar in a diamond anvil cell, using both ultrafast transient mid- and near-IR spectroscopies with 0.1 ps resolution, and cw optical techniques (photo induced absorption (PA) and photoluminescence (PL) in a broad spectral range from 0.2 to 2.2 eV). With increasing P the cw PL band weakens, broadens, and red-shifts by ˜ 2 meV/kbar; whereas the triplet PA red shifts to a lesser extent. The ultrafast PA band of the singlet exciton at ˜ 0.95 eV at ambient splits, blue shifts and acquires a much longer decay component. A second, weak PA band at ˜ 0.33 eV at ambient, dramatically blue-shifts (˜ 3 meV/kbar) and substantially intensifies with P. These pressure-induced effects are discussed considering the interplay of two phases in the MEH-PPV film: a disordered phase with large PL efficiency, and PA that does not change much with P; and a less emissive ordered phase that increases with P, where the interchain coupling substantially increases with P.

  7. Simulation and measurement of different hydrophone components for acoustic particle detection; Simulation und Messung verschiedener Hydrophonkomponenten zur akustischen Teilchendetektion

    Energy Technology Data Exchange (ETDEWEB)

    Salomon, K.S.

    2007-01-26

    A study of piezoceramics as sensitive elements for the use in acoustical astroparticle physics is presented in this work. This study aims to develop underwater microphones (hydrophones) in order to detect thermoacoustic sound pulses, which are produced in neutrino interactions. The sensitive elements of the acoustical detectors, the piezo ceramics, are under investigation in this work. Therefore the equations of a piezo are solved in simulations to derive its macroscopic properties. Especially the impedance and the displacement of the piezo as response to applied voltage are of interest. This is correlated with the electrical and mechanical answer of a piezo when sending. For receiving the resulting voltage or the electrical charge due to applied stress are of interest. In the present studies cylinder and hollow cylinder were analyzed. Insight of the interrelationship between the displacement and the impedance is given. The impedance is fitted with an equivalent circuit, to derive the mechanical analog properties. Furthermore the effect of the piezo geometry to the resonance frequencies is explored. Further calculations were made to reveal the sound field produced by a piezo. Measurements of the impedance with a phase-gain-analyser are made. On the other side the displacement is measured using optical interferometry. Beside the simulation and measurements of the piezosensitive elements a study for a trigger-algorithm using the crosscorrelation is introduced. In this study in situ measurements with low signal amplitudes are used to describe noise. To this noise data signals were added and it was examined how well the signals can be reconstructed. Based on the result of this work and taking commercial available piezoceramic materials into account, the optimal sensitive element of an acoustic neutrino detector is a PZT-5A disc with a diameter of 5 mm and a height of 10 mm. A single detector of this kind is able to detect neutrinos with energies more then one PeV as it

  8. Comparison of bedload transport measurements at the Suggadinbach stream with geophones and modified pipe hydrophones

    Science.gov (United States)

    Chiari, Michael; Berktold, Maximilian; Jäger, Gerald; Hübl, Johannes

    2016-04-01

    A new bedload transport monitoring station has been designed by the Institute of Mountain Risk engineering at the Suggadinbach in Austria (Vorarlberg). In cooperation with the Austrian Service for Torrent and Avalanche Control the station has been installed in June 2013 in a check dam. Two different types of measuring systems are installed: 13 Swiss type geophone sensors record the vibrations of the transported sediment. Additionally 3 modified Japanese pipe hydrophones are mounted under steel plates in order to record the acoustic signal produced by the sediment transport. Both systems can be compared directly because they are arranged consecutively in flow direction. For calibration of the sensors a series of systematic tests have been carried out during low water conditions. Sediment has been fed by a crane with a concrete container. A flume has been installed in order to obtain controlled flow and transport over the measuring system. Four different grain classes up to 64 mm and a mixture of all classes were tested. A total amount of 4 tons were fed during the experiments. The signal was recorded with 9.6 kHz. Frequency analyses were performed for different grain-classes in order to investigate the influence of the grain-size distribution on the shape of the signal and the influence of neighbouring sensors. The standard evaluation and storage procedure for 1 minute aggregated data show that the modified pipe hydrophone is able to detect finer grain-sizes than the geophone sensor.

  9. Three-dimensional tracking of Cuvier's beaked whales' echolocation sounds using nested hydrophone arrays.

    Science.gov (United States)

    Gassmann, Martin; Wiggins, Sean M; Hildebrand, John A

    2015-10-01

    Cuvier's beaked whales (Ziphius cavirostris) were tracked using two volumetric small-aperture (∼1 m element spacing) hydrophone arrays, embedded into a large-aperture (∼1 km element spacing) seafloor hydrophone array of five nodes. This array design can reduce the minimum number of nodes that are needed to record the arrival of a strongly directional echolocation sound from 5 to 2, while providing enough time-differences of arrivals for a three-dimensional localization without depending on any additional information such as multipath arrivals. To illustrate the capabilities of this technique, six encounters of up to three Cuvier's beaked whales were tracked over a two-month recording period within an area of 20 km(2) in the Southern California Bight. Encounter periods ranged from 11 min to 33 min. Cuvier's beaked whales were found to reduce the time interval between echolocation clicks while alternating between two inter-click-interval regimes during their descent towards the seafloor. Maximum peak-to-peak source levels of 179 and 224 dB re 1 μPa @ 1 m were estimated for buzz sounds and on-axis echolocation clicks (directivity index = 30 dB), respectively. Source energy spectra of the on-axis clicks show significant frequency components between 70 and 90 kHz, in addition to their typically noted FM upsweep at 40-60 kHz.

  10. A ‘fitness-wheel-shaped’ MEMS vector hydrophone for 3D spatial acoustic orientation

    Science.gov (United States)

    Wang, Renxin; Liu, Yuan; Xu, Wei; Bai, Bing; Zhang, Guojun; Liu, Jun; Xiong, Jijun; Zhang, Wendong; Xue, Chenyang; Zhang, Binzhen

    2017-04-01

    For the purpose of acquiring precise underwater 3D spatial orientation, a ‘fitness-wheel-shaped’ MEMS vector hydrophone (FWVH) is developed, which achieves monitoring of a tri-axial acoustic pressure differential via appropriate constructional design and strain readout. Compared to the previously reported T-structure-combined vector hydrophone (TSVH) which has a nonlinear relationship between output and external force, using the FWVH it is feasible in principle to achieve a tri-axial match, which make it promising in accurate acoustic orientation. A theoretic model for sensitivity is developed, where torque moment is taken into consideration to match the simulation and practical results. Superior to 3D force sensors, bandwidth is taken as the key index for the FWVH and is designed in detail with a compromise of sensitivity. In view of the bandwidth, the parameters are determined for detecting the signal in the range 20-300 Hz. A vibration test demonstrates tri-axial resonance frequencies. Finally, the frequency response curve of the FWVH shows that tri-axial sensitivities are consistent, agreeing with the analysis and simulation results, which reach  -174 dB (0 dB referring to 1 V µPa-1) at 300 Hz.

  11. Underwater hybrid near-field acoustical holography based on the measurement of vector hydrophone array

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Hybrid near-field acoustical holography(NAH) is developed for reconstructing acoustic radiation from a cylindrical source in a complex underwater environment. In hybrid NAH,we combine statistically optimized near-field acoustical holography(SONAH) and broadband acoustical holography from intensity measurements(BAHIM) to reconstruct the underwater cylindrical source field. First,the BAHIM is utilized to regenerate as much acoustic pressures on the hologram surface as necessary,and then the acoustic pressures are taken as input to the formulation implemented numerically by SONAH. The main advantages of this technology are that the complex pressure on the hologram surface can be reconstructed without reference signal,and the measurement array can be smaller than the source,thus the practicability and efficiency of this technology are greatly enhanced. Numerical examples of a cylindrical source are demonstrated. Test results show that hybrid NAH can yield a more accurate reconstruction than conventional NAH. Then,an experiment has been carried out with a vector hydrophone array. The experimental results show the advantage of hybrid NAH in the reconstruction of an acoustic field and the feasibility of using a vector hydrophone array in an underwater NAH measurement,as well as the identification and localization of noise sources.

  12. Noise Localization Method for Model Tests in a Large Cavitation Tunnel Using a Hydrophone Array

    Directory of Open Access Journals (Sweden)

    Cheolsoo Park

    2016-02-01

    Full Text Available Model tests are performed in order to predict the noise level of a full ship and to control its noise signature. Localizing noise sources in the model test is therefore an important research subject along with measuring noise levels. In this paper, a noise localization method using a hydrophone array in a large cavitation tunnel is presented. The 45-channel hydrophone array was designed using a global optimization technique for noise measurement. A set of noise experiments was performed in the KRISO (Korea Research Institute of Ships & Ocean Engineering large cavitation tunnel using scaled models, including a ship with a single propeller, a ship with twin propellers and an underwater vehicle. The incoherent broadband processors defined based on the Bartlett and the minimum variance (MV processors were applied to the measured data. The results of data analysis and localization are presented in the paper. Finally, it is shown that the mechanical noise, as well as the propeller noise can be successfully localized using the proposed localization method.

  13. Portable optical fiber probe-based spectroscopic scanner for rapid cancer diagnosis: a new tool for intraoperative margin assessment.

    Science.gov (United States)

    Lue, Niyom; Kang, Jeon Woong; Yu, Chung-Chieh; Barman, Ishan; Dingari, Narahara Chari; Feld, Michael S; Dasari, Ramachandra R; Fitzmaurice, Maryann

    2012-01-01

    There continues to be a significant clinical need for rapid and reliable intraoperative margin assessment during cancer surgery. Here we describe a portable, quantitative, optical fiber probe-based, spectroscopic tissue scanner designed for intraoperative diagnostic imaging of surgical margins, which we tested in a proof of concept study in human tissue for breast cancer diagnosis. The tissue scanner combines both diffuse reflectance spectroscopy (DRS) and intrinsic fluorescence spectroscopy (IFS), and has hyperspectral imaging capability, acquiring full DRS and IFS spectra for each scanned image pixel. Modeling of the DRS and IFS spectra yields quantitative parameters that reflect the metabolic, biochemical and morphological state of tissue, which are translated into disease diagnosis. The tissue scanner has high spatial resolution (0.25 mm) over a wide field of view (10 cm × 10 cm), and both high spectral resolution (2 nm) and high spectral contrast, readily distinguishing tissues with widely varying optical properties (bone, skeletal muscle, fat and connective tissue). Tissue-simulating phantom experiments confirm that the tissue scanner can quantitatively measure spectral parameters, such as hemoglobin concentration, in a physiologically relevant range with a high degree of accuracy (tissues showed that the tissue scanner can detect small foci of breast cancer in a background of normal breast tissue. This tissue scanner is simpler in design, images a larger field of view at higher resolution and provides a more physically meaningful tissue diagnosis than other spectroscopic imaging systems currently reported in literatures. We believe this spectroscopic tissue scanner can provide real-time, comprehensive diagnostic imaging of surgical margins in excised tissues, overcoming the sampling limitation in current histopathology margin assessment. As such it is a significant step in the development of a platform technology for intraoperative management of cancer, a

  14. Portable optical fiber probe-based spectroscopic scanner for rapid cancer diagnosis: a new tool for intraoperative margin assessment.

    Directory of Open Access Journals (Sweden)

    Niyom Lue

    Full Text Available There continues to be a significant clinical need for rapid and reliable intraoperative margin assessment during cancer surgery. Here we describe a portable, quantitative, optical fiber probe-based, spectroscopic tissue scanner designed for intraoperative diagnostic imaging of surgical margins, which we tested in a proof of concept study in human tissue for breast cancer diagnosis. The tissue scanner combines both diffuse reflectance spectroscopy (DRS and intrinsic fluorescence spectroscopy (IFS, and has hyperspectral imaging capability, acquiring full DRS and IFS spectra for each scanned image pixel. Modeling of the DRS and IFS spectra yields quantitative parameters that reflect the metabolic, biochemical and morphological state of tissue, which are translated into disease diagnosis. The tissue scanner has high spatial resolution (0.25 mm over a wide field of view (10 cm × 10 cm, and both high spectral resolution (2 nm and high spectral contrast, readily distinguishing tissues with widely varying optical properties (bone, skeletal muscle, fat and connective tissue. Tissue-simulating phantom experiments confirm that the tissue scanner can quantitatively measure spectral parameters, such as hemoglobin concentration, in a physiologically relevant range with a high degree of accuracy (<5% error. Finally, studies using human breast tissues showed that the tissue scanner can detect small foci of breast cancer in a background of normal breast tissue. This tissue scanner is simpler in design, images a larger field of view at higher resolution and provides a more physically meaningful tissue diagnosis than other spectroscopic imaging systems currently reported in literatures. We believe this spectroscopic tissue scanner can provide real-time, comprehensive diagnostic imaging of surgical margins in excised tissues, overcoming the sampling limitation in current histopathology margin assessment. As such it is a significant step in the development of a

  15. Functionalization of graphene oxide nanostructures improves photoluminescence and facilitates their use as optical probes in preclinical imaging.

    Science.gov (United States)

    Prabhakar, Neeraj; Näreoja, Tuomas; von Haartman, Eva; Şen Karaman, Didem; Burikov, Sergey A; Dolenko, Tatiana A; Deguchi, Takahiro; Mamaeva, Veronika; Hänninen, Pekka E; Vlasov, Igor I; Shenderova, Olga A; Rosenholm, Jessica M

    2015-06-21

    Recently reported photoluminescent nanographene oxides (nGOs), i.e. nanographene oxidised with a sulfuric/nitric acid mixture (SNOx method), have tuneable photoluminescence and are scalable, simple and fast to produce optical probes. This material belongs to the vast class of photoluminescent carbon nanostructures, including carbon dots, nanodiamonds (NDs), graphene quantum dots (GQDs), all of which demonstrate a variety of properties that are attractive for biomedical imaging such as low toxicity and stable photoluminescence. In this study, the nGOs were organically surface-modified with poly(ethylene glycol)-poly(ethylene imine) (PEG-PEI) copolymers tagged with folic acid as the affinity ligand for cancer cells expressing folate receptors. The functionalization enhanced both the cellular uptake and quantum efficiency of the photoluminescence as compared to non-modified nGOs. The nGOs exhibited an excitation dependent photoluminescence that facilitated their detection with a wide range of microscope configurations. The functionalized nGOs were non-toxic, they were retained in the stained cell population over a period of 8 days and they were distributed equally between daughter cells. We have evaluated their applicability in in vitro and in vivo (chicken embryo CAM) models to visualize and track migratory cancer cells. The good biocompatibility and easy detection of the functionalized nGOs suggest that they could address the limitations faced with quantum dots and organic fluorophores in long-term in vivo biomedical imaging.

  16. Multimodal use of new coumarin-based fluorescent chemosensors: towards highly selective optical sensors for Hg(2+) probing.

    Science.gov (United States)

    Bazzicalupi, Carla; Caltagirone, Claudia; Cao, Zenfeng; Chen, Qibin; Di Natale, Corrado; Garau, Alessandra; Lippolis, Vito; Lvova, Larisa; Liu, Honglai; Lundström, Ingemar; Mostallino, M Cristina; Nieddu, Mattia; Paolesse, Roberto; Prodi, Luca; Sgarzi, Massimo; Zaccheroni, Nelsi

    2013-10-18

    Despite several types of fluorescent sensing molecules have been proposed and examined to signal Hg(2+) ion binding, the development of fluorescence-based devices for in-field Hg(2+) detection and screening in environmental and industrial samples is still a challenging task. Herein, we report the synthesis and characterization of three new coumarin-based fluorescent chemosensors featuring mixed thia/aza macrocyclic framework as receptors units, that is, ligands L1-L3. These probes revealed an OFF-ON selective response to the presence of Hg(2+) ions in MeCN/H2 O 4:1 (v/v), which allowed imaging of this metal ion in Cos-7 cells in vitro. Once included in silica core-polyethylene glycol (PEG) shell nanoparticles or supported on polyvinyl chloride (PVC)-based polymeric membranes, ligands L1-L3 can also selectively sense Hg(2+) ions in pure water. In particular we have developed an optical sensing array tacking advantage of the fluorescent properties of ligand L3 and based on the computer screen photo assisted technique (CSPT). In the device ligand L3 is dispersed into PVC membranes and it quantitatively responds to Hg(2+) ions in natural water samples.

  17. Development of anticavitation hydrophone using a titanium front plate: Effect of the titanium front plate in high-intensity acoustic field with generation of acoustic cavitation

    Science.gov (United States)

    Shiiba, Michihisa; Okada, Nagaya; Kurosawa, Minoru; Takeuchi, Shinichi

    2016-07-01

    Novel anticavitation hydrophones were fabricated by depositing a hydrothermally synthesized lead zirconate titanate polycrystalline film at the back of a titanium front plate. These anticavitation hydrophones were not damaged by the measurement of the acoustic field formed by a high-intensity focused ultrasound (HIFU) device. Their sensitivity was improved by approximately 20 dB over that of the conventional anticavitation hydrophone by modifying their basic structure and materials. The durability of the anticavitation hydrophone that we fabricated was compared by exposing it to a high-intensity acoustic field at the focal point of the HIFU field and in the water tank of an ultrasound cleaner. Therefore, the effect of the surface of the titanium front plate on acoustic cavitation was investigated by exposing such a surface to the high-intensity acoustic field. We found that the fabricated anticavitation hydrophone was robust and was not damaged easily, even in the focused acoustic field where acoustic cavitation occurs.

  18. Back-to-back optical coherence tomography-ultrasound probe for co-registered three-dimensional intravascular imaging with real-time display

    Science.gov (United States)

    Li, Jiawen; Ma, Teng; Jing, Joseph; Zhang, Jun; Patel, Pranav M.; Shung, K. Kirk; Zhou, Qifa; Chen, Zhongping

    2014-03-01

    We have developed a novel integrated optical coherence tomography (OCT)-intravascular ultrasound (IVUS) probe, with a 1.5 mm-long rigid-part and 0.9 mm outer diameter, for real-time intracoronary imaging of atherosclerotic plaques and guiding interventional procedures. By placing the OCT ball lens and IVUS 45MHz single element transducer back-to-back at the same axial position, this probe can provide automatically co-registered, co-axial OCT-IVUS imaging. To demonstrate its capability, 3D OCT-IVUS imaging of a pig's coronary artery in real-time displayed in polar coordinates, as well as images of two major types of advanced plaques in human cadaver coronary segments, was obtained using this probe and our upgraded system. Histology validation is also presented.

  19. Tracking marine mammals and ships with small and large-aperture hydrophone arrays

    Science.gov (United States)

    Gassmann, Martin

    Techniques for passive acoustic tracking in all three spatial dimensions of marine mammals and ships were developed for long-term acoustic datasets recorded continuously over months using custom-designed arrays of underwater microphones (hydrophones) with spacing ranging from meters to kilometers. From the three-dimensional tracks, the acoustical properties of toothed whales and ships, such as sound intensity and directionality, were estimated as they are needed for the passive acoustic abundance estimation of toothed whales and for a quantitative description of the contribution of ships to the underwater soundscape. In addition, the tracks of the toothed whales reveal their underwater movements and demonstrate the potential of the developed tracking techniques to investigate their natural behavior and responses to sound generated by human activity, such as from ships or military SONAR. To track the periodically emitted echolocation sounds of toothed whales in an acoustically refractive environment in the upper ocean, a propagation-model based technique was developed for a hydrophone array consisting of one vertical and two L-shaped subarrays deployed from the floating instrument platform R/P FLIP. The technique is illustrated by tracking a group of five shallow-diving killer whales showing coordinated behavior. The challenge of tracking the highly directional echolocation sounds of deep-diving (whales, in particular Cuvier's beaked whales, was addressed by embedding volumetric small-aperture (≈ 1 m element spacing) arrays into a large-aperture (≈ 1 km element spacing) seafloor array to reduce the minimum number of required receivers from five to two. The capabilities of this technique are illustrated by tracking several groups of up to three individuals over time periods from 10 min to 33 min within an area of 20 km2 in the Southern California Bight. To track and measure the underwater radiated sound of ships, a frequency domain beamformer was implemented for

  20. On-line determination of fatty acid composition in intramuscular fat of Iberian pork loin by NIRs with a remote reflectance fibre optic probe.

    Science.gov (United States)

    González-Martín, I; González-Pérez, C; Alvarez-García, N; González-Cabrera, J M

    2005-02-01

    A near infrared spectrometer equipped with a standard 210/210 bundle remote reflectance fibre-optic probe, with a 5×5 cm quartz window type, was used for the determination of fatty acids in the Longissimus dorsi muscle of Iberian breed swine. The fatty acids C14:0, C16:0, C16:1, C17:0, C17:1, C18:0, C18:1, C18:2, C18:3, Σpolyunsaturated, Σmonounsaturated and Σsaturated were determined in samples of intramuscular fat from Iberian breed swine by direct application of the fibre-optic probe onto the loin sample, with no treatment or manipulation of the sample. The regression method employed was modified partial least squares. The calibration results using the fibre-optic probe for 74 loin samples had multiple correlation coefficients (RSQ) for C14:0, C16:0, C16:1, C17:0, C17:1, C18:0, C18:1, C18:2, C18:3, Σpolyunsaturated, Σmonounsaturated and Σsaturated acid of 0.785, 0.798, 0.788, 0.825, 0.762, 0.765, 0.696, 0.859, 0.878, 0.807, 0.943, 0.858, respectively, and standard errors of prediction corrected for the same fatty acids (%) of 0.08, 0.63, 0.26, 0.02, 0.02, 0.51, 0,77, 0.64, 0.05, 1.06, 0.34, 0.70, respectively. The robustness of the method was checked by applying the fibre-optic probe to unknown samples of Iberian breed pork loin in a slaughterhouse, using 15 samples for the external validation.

  1. Near-infrared spectroscopy (NIRS) with a fibre-optic probe for the prediction of the amino acid composition in animal feeds.

    Science.gov (United States)

    González-Martín, Inmaculada; Alvarez-García, Noelia; González-Cabrera, José Miguel

    2006-05-15

    The amino acids alanine, aspartic acid, glutamic acid, glycine, phenylalanine, valine, lysine, proline, and tyrosine present in feeds with different textures (blocks, tablets, granules and flour (meal) and used in different stages of animal feeding regimes (lactation, growth, maintenance, etc.) were analysed using near-infrared reflectance spectroscopy (NIRS) technology together with a remote reflectance fibre-optic probe. The method allows immediate control of the animal feeds without prior sample treatment or destruction through direct application of the fibre-optic probe on the sample. The regression method used was Modified Partial Least Squares (MPLS). The equations developed to determine the amino acid contents of the feeds afforded high values for the RSQ coefficient (0.814-0.963) in all the amino acids with the exception of lysine (0.687). The statistical prediction descriptors SEP, SEP(C) (with values between 0.134 for valine and 0.015 for aspartic acid) and bias indicated that the amino acid values in feeds predicted with NIRS with a fibre optic probe are comparable to those obtained with the chemical ion-exchange HPLC method.

  2. MEMS-based handheld scanning probe with pre-shaped input signals for distortion-free images in Gabor-domain optical coherence microscopy.

    Science.gov (United States)

    Cogliati, Andrea; Canavesi, Cristina; Hayes, Adam; Tankam, Patrice; Duma, Virgil-Florin; Santhanam, Anand; Thompson, Kevin P; Rolland, Jannick P

    2016-06-13

    High-speed scanning in optical coherence tomography (OCT) often comes with either compromises in image quality, the requirement for post-processing of the acquired images, or both. We report on distortion-free OCT volumetric imaging with a dual-axis micro-electro-mechanical system (MEMS)-based handheld imaging probe. In the context of an imaging probe with optics located between the 2D MEMS and the sample, we report in this paper on how pre-shaped open-loop input signals with tailored non-linear parts were implemented in a custom control board and, unlike the sinusoidal signals typically used for MEMS, achieved real-time distortion-free imaging without post-processing. The MEMS mirror was integrated into a compact, lightweight handheld probe. The MEMS scanner achieved a 12-fold reduction in volume and 17-fold reduction in weight over a previous dual-mirror galvanometer-based scanner. Distortion-free imaging with no post-processing with a Gabor-domain optical coherence microscope (GD-OCM) with 2 μm axial and lateral resolutions over a field of view of 1 × 1 mm2 is demonstrated experimentally through volumetric images of a regular microscopic structure, an excised human cornea, and in vivo human skin.

  3. A streptavidin paramagnetic-particle based competition assay for the evaluation of the optical selectivity of quadruplex nucleic acid fluorescent probes.

    Science.gov (United States)

    Largy, Eric; Hamon, Florian; Teulade-Fichou, Marie-Paule

    2012-05-01

    Although quadruplex nucleic acids are thought to be involved in many biological processes, they are massively overwhelmed by duplex DNA in the cell. Small molecules, able to probe quadruplex nucleic acids with high optical selectivity, could possibly achieve the visualization of these processes. The aim of the method described herein is to evaluate quickly the optical selectivity of quadruplex nucleic acid probes, in isothermal conditions, using widely available materials, small quantities of oligonucleotides and virtually any kind and quantity of biological competitor. The assay relies on the use of streptavidin-coated paramagnetic particles and biotinylated quadruplex forming oligonucleotides, allowing a quick and easy separation of the quadruplex target from the competitor. In the present study, two quadruplex nucleic acids (the DNA and RNA human telomeric repeats) have been used as targets while a duplex DNA oligonucleotide, total DNA, total RNA, another quadruplex nucleic acid and a protein have been used as competitors. The optical selectivity of various probes, displaying different photophysical properties and binding selectivities, has been successfully examined, allowing the identification of a best candidate for further cell microscopy experiments. This assay allows a quick and reliable assessment of the labeling properties of a quadruplex binder in cellular environment conditions. It is an interesting alternative to gel electrophoresis experiments since it is performed in solution, has a well-resolved separation system and allows easy quantifications.

  4. Functionalization of graphene oxide nanostructures improves photoluminescence and facilitates their use as optical probes in preclinical imaging

    Science.gov (United States)

    Prabhakar, Neeraj; Näreoja, Tuomas; von Haartman, Eva; Şen Karaman, Didem; Burikov, Sergey A.; Dolenko, Tatiana A.; Deguchi, Takahiro; Mamaeva, Veronika; Hänninen, Pekka E.; Vlasov, Igor I.; Shenderova, Olga A.; Rosenholm, Jessica M.

    2015-06-01

    Recently reported photoluminescent nanographene oxides (nGOs), i.e. nanographene oxidised with a sulfuric/nitric acid mixture (SNOx method), have tuneable photoluminescence and are scalable, simple and fast to produce optical probes. This material belongs to the vast class of photoluminescent carbon nanostructures, including carbon dots, nanodiamonds (NDs), graphene quantum dots (GQDs), all of which demonstrate a variety of properties that are attractive for biomedical imaging such as low toxicity and stable photoluminescence. In this study, the nGOs were organically surface-modified with poly(ethylene glycol)-poly(ethylene imine) (PEG-PEI) copolymers tagged with folic acid as the affinity ligand for cancer cells expressing folate receptors. The functionalization enhanced both the cellular uptake and quantum efficiency of the photoluminescence as compared to non-modified nGOs. The nGOs exhibited an excitation dependent photoluminescence that facilitated their detection with a wide range of microscope configurations. The functionalized nGOs were non-toxic, they were retained in the stained cell population over a period of 8 days and they were distributed equally between daughter cells. We have evaluated their applicability in in vitro and in vivo (chicken embryo CAM) models to visualize and track migratory cancer cells. The good biocompatibility and easy detection of the functionalized nGOs suggest that they could address the limitations faced with quantum dots and organic fluorophores in long-term in vivo biomedical imaging.Recently reported photoluminescent nanographene oxides (nGOs), i.e. nanographene oxidised with a sulfuric/nitric acid mixture (SNOx method), have tuneable photoluminescence and are scalable, simple and fast to produce optical probes. This material belongs to the vast class of photoluminescent carbon nanostructures, including carbon dots, nanodiamonds (NDs), graphene quantum dots (GQDs), all of which demonstrate a variety of properties that are

  5. Method for simultaneous luminescence sensing of two species using optical probes of different decay time, and its application to an enzymatic reaction at varying temperature.

    Science.gov (United States)

    Nagl, Stefan; Stich, Matthias I J; Schäferling, Michael; Wolfbeis, Otto S

    2009-02-01

    Chemical sensing, imaging and microscopy based on the use of fluorescent probes has so far been limited almost exclusively to the detection of a single parameter at a time. We present a scheme that can overcome this limitation by enabling optical sensing of two parameter simultaneously and even at identical excitation and emission wavelengths of two probes provided (a) their decay times are different enough to enable two time windows to be recorded, and (b) the emission of the shorter-lived probe decays to below the detectable limit while that of the other still can be measured. We refer to this new scheme as the dual lifetime determination (DLD) method and show that it can be widely varied by appropriate choice of probes and experimental settings. DLD is demonstrated to work by sensing oxygen and temperature independently from each other by making use of two probes, one for oxygen (a platinum porphyrin dissolved in polystyrene), and one for temperature [a europium complex dissolved in poly(vinyl methylketone)]. DLD was applied to monitor the consumption of oxygen in the glucose oxidase-catalyzed oxidation of glucose at varying temperatures. The scheme is expected to have further applications in cellular assays and biophysical imaging.

  6. Optical probes in biology

    CERN Document Server

    Zhang, Jin; Schultz, Carsten

    2015-01-01

    Introduction and BasicsEngineering of Optimized Fluorescent Proteins: An Overview from a Cyan and FRET Perspective Lindsay Haarbosch, Joachim Goedhart, Mark A. Hink, Laura van Weeren, Daphne S. Bindels, and Theodorus W.J. GadellaFluorescent Imaging Techniques: FRET and Complementary Methods Stefan Terjung and Yury BelyaevTracking: Sensors for Tracking BiomoleculesProtein-Based Calcium Sensors Thomas Thestrup and Oliver GriesbeckMonitoring Membrane Lipids with Protein Domains Expressed in Living Cells Peter Varnai

  7. Optical Mach Probe Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Michigan Aerospace Corporation (MAC) proposes to advance NASA's nonintrusive spatially- and temporally-resolved Interferometric Rayleigh Scattering (IRS) technology...

  8. Fiber Optic Oscilloscope Probe

    Science.gov (United States)

    2013-06-01

    California, 94551 L645 Abstract In the recent development of high voltage solid state pulsed power systems, the ability to monitor low voltage...developing a Solid State Kicker Pulser for DARHT-2. The pulser is a 20kV induction adder circuit with rise and fall times of less than 10ns. The pulser is...designed around an array of MOSFETs. A critical diagnostic point for monitoring and troubleshooting this pulser is the gate of the MOSFET. In

  9. The SMARTS Multi-epoch Optical Spectroscopy Atlas (SAMOSA): Using Emission Line Variability to Probe the Location of the Blazar Gamma-emitting Region

    CERN Document Server

    Isler, Jedidah C; Bailyn, C; Smith, P S; Coppi, P; Brady, M; Macpherson, E; Hasan, I; Buxton, M

    2015-01-01

    We present multi-epoch optical spectroscopy of seven southern Fermi-monitored blazars from 2008 - 2013 using the Small and Medium Aperture Research Telescope System (SMARTS), with supplemental spectroscopy and polarization data from the Steward Observatory. We find that the emission lines are much less variable than the continuum; 4 of 7 blazars had no detectable emission line variability over the 5 years. This is consistent with photoionization primarily by an accretion disk, allowing us to use the lines as a probe of disk activity. Comparing optical emission line flux with Fermi $\\gamma$-ray flux and optical polarized flux, we investigate whether relativistic jet variability is related to the accretion flow. In general, we see no such dependence, suggesting the jet variability is likely caused by internal processes like turbulence or shock acceleration rather than a variable accretion rate. However, three sources showed statistically significant emission line flares in close temporal proximity to very large...

  10. Pure quadratic or higher-order optical effects in anisotropic crystals induced by external dc fields and probed by a single low-intensity plane electromagnetic wave

    Science.gov (United States)

    Melnichuk, Mike; Wood, Lowell T.

    2017-07-01

    The determination of a clear theoretical demarcation between a true or a false quadratic or higher-order low-intensity optical effect induced by an externally applied static or quasistatic (dc) vector field in anisotropic crystals is the scope of the present work. A complete set of necessary and sufficient conditions required for the practical possibility of direct detection, measurement, and tabulation of only those pure optical contributions is finally obtained. The dc electro-optic effect stands out as the most representative of all of these low-power dc optical effects. However, although the dc Kerr effect remains the main topic of application of the analytical treatment developed in this work, the current theoretical formalism is extended to include other dc conventional crystal optics effects, such as electrogyration, electroabsorption, and externally induced ray or energy propagation. Even more, the theoretical conditions are further generalized to apply to any pure higher-order crystal optics effect induced by external dc fields. These can be electric, magnetic, force, and even temperature or concentration gradient fields. The current treatment does not extend to multiple-beam high-intensity nonlinear optics effects induced by optical (ac) fields. Compared to previously published expressions, a more general Fresnel equation is also provided here together with the most general Jones vectors describing the eigenpolarizations of the single probing beam of light. All the generalizations and extensions mentioned in this article are valid as long as the field-dependent coefficients of the particular optical effect under consideration satisfy the equation of a positive-definite complex Hermitian form.

  11. Motion-compensated hand-held common-path Fourier-domain optical coherence tomography probe for image-guided intervention

    Science.gov (United States)

    Huang, Yong; Song, Cheol; Liu, Xuan; Kang, Jin U.

    2013-03-01

    A motion-compensated hand-held common-path Fourier-domain optical coherence tomography imaging probe has been developed for image guided intervention during microsurgery. A hand-held prototype instrument was designed and fabricated by integrating an imaging fiber probe inside a stainless steel needle which is attached to the ceramic shaft of a piezoelectric motor housed in an aluminum handle. The fiber probe obtains A-scan images. The distance information was extracted from the A-scans to track the sample surface distance and a fixed distance was maintained by a feedback motor control which effectively compensated hand tremor and target movements in the axial direction. Graphical user interface, real-time data processing, and visualization based on a CPU-GPU hybrid programming architecture were developed and used in the implantation of this system. To validate the system, free-hand optical coherence tomography images using various samples were obtained. The system can be easily integrated into microsurgical tools and robotics for a wide range of clinical applications. Such tools could offer physicians the freedom to easily image sites of interest with reduced risk and higher image quality.

  12. Fiber-optic system for dual-modality imaging of glucose probes 18F-FDG and 6-NBDG in atherosclerotic plaques.

    Directory of Open Access Journals (Sweden)

    Raiyan T Zaman

    Full Text Available Atherosclerosis is a progressive inflammatory condition that underlies coronary artery disease (CAD-the leading cause of death in the United States. Thus, the ultimate goal of this research is to advance our understanding of human CAD by improving the characterization of metabolically active vulnerable plaques within the coronary arteries using a novel catheter-based imaging system. The aims of this study include (1 developing a novel fiber-optic imaging system with a scintillator to detect both 18F and fluorescent glucose probes, and (2 validating the system on ex vivo murine plaques.A novel design implements a flexible fiber-optic catheter consisting of both a radio-luminescence and a fluorescence imaging system to detect radionuclide 18F-fluorodeoxyglucose (18F-FDG and the fluorescent analog 6-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-ylamino-6-Deoxyglucose (6-NBDG, respectively. Murine macrophage-rich atherosclerotic carotid plaques were imaged ex vivo after intravenous delivery of 18F-FDG or 6-NBDG. Confirmatory optical imaging by IVIS-200 and autoradiography were also performed.Our fiber-optic imaging system successfully visualized both 18F-FDG and 6-NBDG probes in atherosclerotic plaques. For 18F-FDG, the ligated left carotid arteries (LCs exhibited 4.9-fold higher radioluminescence signal intensity compared to the non-ligated right carotid arteries (RCs (2.6 × 10(4 ± 1.4 × 10(3 vs. 5.4 × 10(3 ± 1.3 × 10(3 A.U., P = 0.008. Similarly, for 6-NBDG, the ligated LCs emitted 4.3-fold brighter fluorescent signals than the control RCs (1.6 × 10(2 ± 2.7 × 10(1 vs. 3.8 × 10(1 ± 5.9 A.U., P = 0.002. The higher uptake of both 18F-FDG and 6-NBDG in ligated LCs were confirmed with the IVIS-200 system. Autoradiography further verified the higher uptake of 18F-FDG by the LCs.This novel fiber-optic imaging system was sensitive to both radionuclide and fluorescent glucose probes taken up by murine atherosclerotic plaques. In addition, 6-NBDG is a

  13. Influence of the Electronic Structure and Optical Properties of CeO2 and UO2 for Characterization with UV-Laser Assisted Atom Probe Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Billy Valderrama; H.B. Henderson; C. Yablinsky; J. Gan; T.R. Allen; M.V. Manuel

    2015-09-01

    Oxide materials are used in numerous applications such as thermal barrier coatings, nuclear fuels, and electrical conductors and sensors, all applications where nanometer-scale stoichiometric changes can affect functional properties. Atom probe tomography can be used to characterize the precise chemical distribution of individual species and spatially quantify the oxygen to metal ratio at the nanometer scale. However, atom probe analysis of oxides can be accompanied by measurement artifacts caused by laser-material interactions. In this investigation, two technologically relevant oxide materials with the same crystal structure and an anion to cation ratio of 2.00, pure cerium oxide (CeO2) and uranium oxide (UO2) are studied. It was determined that electronic structure, optical properties, heat transfer properties, and oxide stability strongly affect their evaporation behavior, thus altering their measured stoichiometry, with thermal conductance and thermodynamic stability being strong factors.

  14. Numerical analysis of GRIN lens based miniature probes for optical coherence tomography%基于GRIN镜头的小型OCT探头的数值分析

    Institute of Scientific and Technical Information of China (English)

    王驰; 毛幼馨; 唐智; 方臣; 于瀛洁; 齐博

    2011-01-01

    Numerical simulation technology was investigated by using the optical software GLAD to design Gradient Index(GRIN)lens based miniature probes for imaging of Optical Coherence Tomography(OCT).Firstly,the basic features of the GRIN lens were overviewed,and design methods for GRIN lens based optical probes were discussed.Then,the probe model consisting of a single mode fiber,a glass rod spacer and a GRIN lens were simulated.The simulating results show that the numerical simulation technique using GLAD can provide an intuitive and effective method for design of miniaturized probes and verification of their optical performance.In addition,the spacer can improve the optical properties of the GRIN lens based optical probes for there exists a suitable range of the spacer lengths in the glass rod.It shows that the working distance of the probe will be greater than 1.0 mm and the focus spot size less than 40 μm when the constant length of GRIN lens is to be 0.1 mm and the spacer length range from 0.8 to 1.1 mm.%利用光学软件GLAD的数值仿真技术设计了用于光学相干层析技术成像的基于梯度折射率(GRIN)镜头的小型化探头.首先,简述了梯度折射率镜头的基本特性,讨论了基于梯度折射率镜头的光学探头的设计方法;然后,对由单模光纤、玻璃棒隔片和梯度折射率镜头构成的探头模型进行了仿真.结果显示,利用GLAD的数值仿真技术为小型化探头的设计及其光学性能的验证提供了一种直观而有效的方法.另外,玻璃棒隔片存在一个适当的长度范围,可以改善设计的光学探头的传光性能.在所给仿真条件下,如设定梯度折射率镜头长0.1 mm、玻璃棒隔片长度为0.8~1.1 mm,则探头的工作距离将超过1.0 mm,而聚焦光斑的尺寸<40 μm.

  15. Determination of fatty acids in the subcutaneous fat of Iberian breed swine by near infrared spectroscopy (NIRS) with a fibre-optic probe.

    Science.gov (United States)

    González-Martín, I; González-Pérez, C; Hernández-Méndez, J; Alvarez-García, N

    2003-10-01

    A near infrared spectrometer equipped with a standard 1210/210 bundle remote reflectance fibre-optic probe, with a 5×5 cm quartz window, was used for the determination of fatty acids in the subcutaneous fat of Iberian pigs. A comparative study was made of the determination of fatty acids (C14:0, C16:0, C18:0, C18:1, C18:2, C18:3, C20: 1, Σpolyunsaturated, Σmonounsaturated and Σsaturated) in samples of subcutaneous fat from Iberian pigs by direct application of the fibre-optic probe on samples of whole subcutaneous fat and with cam-lock cups, assessing extracts of total lipids with diethyl ether. The regression method employed was modified partial least squares (MPLS). Calibration of 157 samples, using the fibre optic probe, allowed determination of fatty acids in the following ranges: C14:0 (0.78-1.77), C16:0 (15.87-29.74), C18:0 (4.61-15.90), C18:1 (43.50-61.27), C18:2 (2.03-13.94), C18:3 (0.13-1.14), C20:1 (0.45-2.32), Σpolyunsaturated (2.31-14.82), Σmonounsaturated (47.37-65.62), Σsaturated (22.09-47.31), with corrected standard errors of prediction SEP(C) of 0.093, 0.56, 0.67, 0.94, 0.42, 0.10, 0.20, 0.46, 0.94, 0.83, respectively. The robustness of the method using the fibre-optic probe was tested in a slaughterhouse using 23 samples for external validation, giving multiple correlation coefficients (RSQ) for C14:0, C16:0, C18:0, C18:1, C18:2, C18:3 C20:1, Σpolyunsaturated, Σmonounsaturated, Σsaturated acids of 0.72, 0.94, 0.72, 0.79, 0.88, 0.55, 0.17, 0.88, 0.74, and 0.90, respectively, and a corrected standard error of prediction [SEP(C)] for these acids (%) of 0.11, 0.60, 0.84, 1.20, 0.77, 0.11, 0.30, 0.76, 1.21, and 1.18, respectively.

  16. Hydrophone identiflcation and charaderization of Cynoscion squamipinnis (Perciformes: Sciaenidae) spawning sites in the Gulf of Nicoya, Costa Rica

    OpenAIRE

    Baltz, Donald M; Campos M, Jorge M

    2015-01-01

    A hydrophone survey of the northem Gulf of Nicoya was conducted to identify spawning sites used by the corvina aguada (Cynoscíon squamapinnis). Between July 14, and July 17, 1992, thirty-one stations were surveyed during late aftemoon and evening hours. Large aggregations of drumming corvina were located as early as 1606 hrs, but were generally restricted to stations characterized by aboye average depth and moving water. Drumming activity by C. squamapinnis peaked between 1655 and 1910 hrs on...

  17. Observations and Bayesian location methodology of transient acoustic signals (likely blue whales) in the Indian Ocean, using a hydrophone triplet.

    Science.gov (United States)

    Le Bras, Ronan J; Kuzma, Heidi; Sucic, Victor; Bokelmann, Götz

    2016-05-01

    A notable sequence of calls was encountered, spanning several days in January 2003, in the central part of the Indian Ocean on a hydrophone triplet recording acoustic data at a 250 Hz sampling rate. This paper presents signal processing methods applied to the waveform data to detect, group, extract amplitude and bearing estimates for the recorded signals. An approximate location for the source of the sequence of calls is inferred from extracting the features from the waveform. As the source approaches the hydrophone triplet, the source level (SL) of the calls is estimated at 187 ± 6 dB re: 1 μPa-1 m in the 15-60 Hz frequency range. The calls are attributed to a subgroup of blue whales, Balaenoptera musculus, with a characteristic acoustic signature. A Bayesian location method using probabilistic models for bearing and amplitude is demonstrated on the calls sequence. The method is applied to the case of detection at a single triad of hydrophones and results in a probability distribution map for the origin of the calls. It can be extended to detections at multiple triads and because of the Bayesian formulation, additional modeling complexity can be built-in as needed.

  18. Flow induced noise calculations for non-axially distributed hydrophones in towed arrays

    Institute of Scientific and Technical Information of China (English)

    WANG Bin; TANG Weilin; FAN Jun

    2009-01-01

    Two improvements are put forward on the analyses of flow induced noise in towed arrays. First, the differences between Corcos/Carpenter pressure fluctuation models have been discussed at length, as well as flow induced noise calculated with these two models. Second, flow induced noise received by the finite hydrophones distributed non-axially is discussed and the relevant power spectrum is deduced. The results show that there are some disparities between the wavenumber spectrums and the responses of flow induced noise of these two models. Flow induced noise is closely related with the tow speed, the tube radius and the off-axis distance. The numerical analyses with Carpenter model indicate that the power spectrum of flow induced noise will increase 24 dB approximately with the tow speed doubled, decrease with the radius of the tube, and increase with the off-axis distance. The tube radius and the off-axis distance have greater influence on the high-frequency components than on the low-frequency components.

  19. Long-term seismicity of the Reykjanes Ridge (North Atlantic) recorded by a regional hydrophone array

    Science.gov (United States)

    Goslin, Jean; Lourenço, Nuno; Dziak, Robert P.; Bohnenstiehl, DelWayne R.; Haxel, Joe; Luis, Joaquim

    2005-08-01

    The seismicity of the northern Mid-Atlantic Ridge was recorded by two hydrophone networks moored in the sound fixing and ranging (SOFAR) channel, on the flanks of the Mid-Atlantic Ridge, north and south of the Azores. During its period of operation (05/2002-09/2003), the northern `SIRENA' network, deployed between latitudes 40° 20'N and 50° 30'N, recorded acoustic signals generated by 809 earthquakes on the hotspot-influenced Reykjanes Ridge. This activity was distributed between five spatio-temporal event clusters, each initiated by a moderate-to-large magnitude (4.0-5.6 M) earthquake. The rate of earthquake occurrence within the initial portion of the largest sequence (which began on 2002 October 6) is described adequately by a modified Omori law aftershock model. Although this is consistent with triggering by tectonic processes, none of the Reykjanes Ridge sequences are dominated by a single large-magnitude earthquake, and they appear to be of relatively short duration (0.35-4.5 d) when compared to previously described mid-ocean ridge aftershock sequences. The occurrence of several near-equal magnitude events distributed throughout each sequence is inconsistent with the simple relaxation of mainshock-induced stresses and may reflect the involvement of magmatic or fluid processes along this deep (>2000 m) section of the Reykjanes Ridge.

  20. Matched field noise suppression: Principle with application to towed hydrophone line array

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Discrete noise source suppression in underwater acoustic channel has attracted great attention in recent years. The paper proposes a new principle for dealing with the problem. This new principle is called matched field noise suppression (MFNS). Based on a previous work of the authors group, a full understanding about how a discrete noise source shows effects on the performance of a towed hydrophone line array has been obtained. In light of that finding, MFNS is proposed, which explores and utilizes the characteristics of the noise transmission channel to achieve much greater suppression of the noise in comparison with existing approaches. MFNS combines the concept of matched field processing (MFP) and optimal sensor array processing (OSAP) together to suppress the discrete noise source and to maintain an optimal beam for receiving far-field wanted plane wave signals. A MFNS beam-former is deduced in constraint with signal plane-wave response being unit and noise matched field response being zero. A closed-form solution of the weight vector for the beam-former is given. Computer simulation results agree well to the theoretical analysis.

  1. Localization of underwater moving sound source based on time delay estimation using hydrophone array

    Science.gov (United States)

    Rahman, S. A.; Arifianto, D.; Dhanardono, T.; Wirawan

    2016-11-01

    Signal and noise of an underwater moving sound source is used to track the azimuth of a target. Uniform linear array with four hydrophones is used to detect azimuth of target by obtain the time delay information to get azimuth information. Success rate of time delay estimation influenced by characteristics of sound propagation like reflection, reverberation, etc. Experiment in real environment was done to analyze performance of the cross correlation (CC) and generalized cross correlation with the phase transform (PHAT) weighting to estimate time delay between two signal. The simulation done by convolute two signal that has been given time delay and impulse response of the medium test. Then the time delay of two signal estimated by CC and PHAT algorithm in Matlab in the various SNR. Then the algorithm tested in a pool to detect stationary and moving position of sound source. Result of the simulation and experiment in real environment shown that PHAT better than CC. The best azimuth tracking achieved by using PHAT algorithm with error of 0 - 9.48 degree in stationary position. In moving sound experiments, tracking the bearing and azimuth of the mini vessel (sound source) can be done by time delay estimation using PHAT.

  2. Marine mammal tracks from two-hydrophone acoustic recordings made with a glider

    Science.gov (United States)

    Küsel, Elizabeth T.; Munoz, Tessa; Siderius, Martin; Mellinger, David K.; Heimlich, Sara

    2017-04-01

    A multinational oceanographic and acoustic sea experiment was carried out in the summer of 2014 off the western coast of the island of Sardinia, Mediterranean Sea. During this experiment, an underwater glider fitted with two hydrophones was evaluated as a potential tool for marine mammal population density estimation studies. An acoustic recording system was also tested, comprising an inexpensive, off-the-shelf digital recorder installed inside the glider. Detection and classification of sounds produced by whales and dolphins, and sometimes tracking and localization, are inherent components of population density estimation from passive acoustics recordings. In this work we discuss the equipment used as well as analysis of the data obtained, including detection and estimation of bearing angles. A human analyst identified the presence of sperm whale (Physeter macrocephalus) regular clicks as well as dolphin clicks and whistles. Cross-correlating clicks recorded on both data channels allowed for the estimation of the direction (bearing) of clicks, and realization of animal tracks. Insights from this bearing tracking analysis can aid in population density estimation studies by providing further information (bearings), which can improve estimates.

  3. Acoustic monitoring in the Ross Sea, Antarctica, using hydrophone of the Ocean Bottom Seismometer

    Science.gov (United States)

    Yun, Sukyoung; Lee, Won Sang; Kuk Hong, Jong; Yoo, Hyun Jae; Park, Yongcheol; Schmidt-Aursch, Mechita; Geissler, Wolfram H.

    2016-04-01

    Although a number of active source seismic experiments have been conducted over the last few decades to investigate the crustal structure in the Ross Sea, Antarctica, long-term observation to monitor underwater tectonic activities and changes in the cryospheric environment still remains challenging due to existence of sea ice in the study region. Korea Polar Research Institute has accomplished successful deployment of ocean bottom seismometers (OBS) in the Ross Sea collaborating with Alfred Wegener Institute during the period of 2011-2012 and 2014 by Korean icebreaker RV Araon. The OBS system manufactured by K.U.M. contains a hydrophone sensor that allow us to monitor underwater acoustics generated by tectonic and ice-related events. We present spectrograms of the continuous hydroacoustic data and various types of signals, e.g. seismic T-waves, iceequakes, and tremors. There are periodic and harmonic tremors that might be related with tidal modulation, and the seasonal variation of the background noise seems to be related with sea ice concentration.

  4. 四发射单接收光学非接触测头%A New Optical Noncontact Probe with Four Incidence Lights and a Receptor

    Institute of Scientific and Technical Information of China (English)

    张国雄; 那永林; 郭敬滨; 樊玉铭; 裘祖荣; 杜颖; 解则晓

    2006-01-01

    研究开发了一种具有4个发射光源和1个CCD摄像机作为接收装置的光学非接触测头.测头可以用来测量包括具有强反射表面的曲面.测头基于三角法工作原理.在恰当设计的情况下,至多只有1路从工件表面反射回来的光,能够进入CCD摄像机.通过将相应通道切断,很容易消除镜面反射光的影响.这时测头就相当于1个三发射单接收光学非接触测头.测头可以同时用来测量表面的位置和方向.对于具有很大倾斜的表面具测头仍能正常工作.采用干涉滤光片消除了环境光的影响.提出了一种系统的标定方法.通过对量块的测量证实了系统工作的正确性和有效性并给出了实验结果.%An optical noncontact probe with four incident lights and a receptor in form of a CCD camera has been developed. This probe can be used for measuring sculptured surfaces including high-reflective ones. The probe works on triangulation principle. By proper design under any situation only no more than one reflecting light from the workpiece goes to the CCD camera and it is easy to eliminate the effect of specular reflection by switching the corresponding channel off and the probe works as a probe with three light sources and a receptor. This probe can be used for measuring both the position and inclination of the surface. It allows measuring parts with very large inclination. An interference filter is introduced to the probe to eliminate the influences of the environment light. A method for system calibration is proposed. The effectiveness of the proposed system has been tested by measuring gage blocks. Experimental results are presented.

  5. A Bloch equation approach to intensity dependent optical spectra of light harvesting complex II: excitation dependence of light harvesting complex II pump-probe spectra.

    Science.gov (United States)

    Richter, Marten; Renger, Thomas; Knorr, Andreas

    2008-01-01

    On the basis of the recent progress in the resolution of the structure of the antenna light harvesting complex II (LHC II) of the photosystem II, we propose a microscopically motivated theory to predict excitation intensity-dependent spectra. We show that optical Bloch equations provide the means to include all 2( N ) excited states of an oligomer complex of N coupled two-level systems and analyze the effects of Pauli Blocking and exciton-exciton annihilation on pump-probe spectra. We use LHC Bloch equations for 14 Coulomb coupled two-level systems, which describe the S (0) and S (1) level of every chlorophyll molecule. All parameter introduced into the Hamiltonian are based on microscopic structure and a quantum chemical model. The derived Bloch equations describe not only linear absorption but also the intensity dependence of optical spectra in a regime where the interplay of Pauli Blocking effects as well as exciton-exciton annihilation effects are important. As an example, pump-probe spectra are discussed. The observed saturation of the spectra for high intensities can be viewed as a relaxation channel blockade on short time scales due to Pauli blocking. The theoretical investigation is useful for the interpretation of the experimental data, if the experimental conditions exceed the low intensity pump limit and effects like strong Pauli Blocking and exciton-exciton annihilation need to be considered. These effects become important when multiple excitations are generated by the pump pulse in the complex.

  6. In vivo optical imaging of acute cell death using a near-infrared fluorescent zinc-dipicolylamine probe.

    Science.gov (United States)

    Smith, Bryan A; Gammon, Seth T; Xiao, Shuzhang; Wang, Wei; Chapman, Sarah; McDermott, Ryan; Suckow, Mark A; Johnson, James R; Piwnica-Worms, David; Gokel, George W; Smith, Bradley D; Leevy, W Matthew

    2011-04-01

    Cell death is a fundamental biological process that is present in numerous disease pathologies. Fluorescent probes that detect cell death have been developed for a myriad of research applications ranging from microscopy to in vivo imaging. Here we describe a synthetic near-infrared (NIR) conjugate of zinc(II)-dipicolylamine (Zn²+-DPA) for in vivo imaging of cell death. Chemically induced in vivo models of myopathy were established using an ionphore, ethanol, or ketamine as cytotoxins. The Zn²+-DPA fluorescent probe or corresponding control was subsequently injected, and whole animal fluorescence imaging demonstrated probe uptake at the site of muscle damage, which was confirmed by ex vivo and histological analyses. Further, a comparative study with a NIR fluorescent conjugate Annexin V showed less intense uptake at the site of muscle damage and high accumulation in the bladder. The results indicate that the fluorescent Zn²+-DPA conjugate is an effective probe for in vivo cell death detection and in some cases may be an appropriate alternative to fluorescent Annexin V conjugates.

  7. Optimizing the fabrication of aluminum-coated fiber probes and their application to optical near-field lithography

    DEFF Research Database (Denmark)

    Madsen, S; Holme, NCR; Ramanujam, PS

    1998-01-01

    We report on routine fabrication of fiber probes suitable for metal coating. We have investigated how aperture sizes ranging from 75 to 300 nm can be produced using an appropriate set of pulling parameters in a combined heating/pulling process. The quality of the metal coating has been investigat...

  8. A scanning probe-based pick-and-place procedure for assembly of integrated quantum optical hybrid devices

    CERN Document Server

    Schell, Andreas W; Schröder, Tim; Wolters, Janik; Aichele, Thomas; Benson, Oliver

    2011-01-01

    Integrated quantum optical hybrid devices consist of fundamental constituents such as single emitters and tailored photonic nanostructures. A reliable fabrication method requires the controlled deposition of active nanoparticles on arbitrary nanostructures with highest precision. Here, we describe an easily adaptable technique that employs picking and placing of nanoparticles with an atomic force microscope combined with a confocal setup. In this way, both the topography and the optical response can be monitored simultaneously before and after the assembly. The technique can be applied to arbitrary particles. Here, we focus on nanodiamonds containing single nitrogen vacancy centers, which are particularly interesting for quantum optical experiments on the single photon and single emitter level.

  9. Radar model fusion of asteroid (4179) Toutatis via its optical images observed by Chang'e-2 probe

    Science.gov (United States)

    Zhao, Wei; Xiao, Ting; Liu, Peng; Sun, Lei; Huang, Jiangchuan; Tang, Xianglong

    2016-06-01

    Asteroid (4179) Toutatis has been modeling by ground-based radar observations until Dec 13th, 2012, when distinct optical images of Toutatis were captured during the Chang'e-2 flyby at the shortest distance for the first time. The surface details on Toutatis in the optical images are abundant enough to reinforce the radar model descriptions. Under this context, we customized a method of frequency domain data fusion, which combines the topography information of radar model and the 3rd dimension information estimated from optical image by shape from shading algorithm, and gave out a new Toutatis' radar model. A model with abundant surface characteristics had been resulted.

  10. A Glimpse of Our Journey into the Design of Optical Probes in Self-assembled Surfactant Aggregates.

    Science.gov (United States)

    Dey, Nilanjan; Bhattacharya, Santanu

    2016-08-01

    Dynamic self-assembling amphiphilic surfactant molecules, popularly known as "micelles", have received widespread attention, due to their ability to modulate the photophysical properties of various organic dyes upon encapsulation. Along with their well-known use as cleaning agents, catalysts in organic reactions, and even for drug delivery purposes, these surfactant assemblies also show promising pertinence in the recognition of both ionic and nonionic targeted analytes. Low micropolarity and relatively hydrophobic environments promote their interaction with ionic analytes, whereas neutral species mostly affect the aggregation pattern of the probe molecules upon partitioning inside the micellar hydrophobic milieu. The environment-sensitive nature of micelle-based self-assembled probes also prompts us to devise new sensor arrays for the recognition of multiple analytes. While this account will largely focus on our own work in developing surfactant-triggered self-assembled sensors, our findings have been placed in the context of the relevant contributions from others during their strategic evolution.

  11. Customization of an optical probe device and validation of a signal processing procedure to study gas-liquid-solid flows. Application to a three-phase internal-loop Gas-lift Bioreactor

    OpenAIRE

    Mota, A; Ferreira, António; Vicente, A.A.; Sechet, P.; Martins, Jean; Teixeira, J. A.; Cartellier, Alain

    2015-01-01

    The study of local hydrodynamic properties of three-phase bioreactors in biotechnology processes is of great importance, mainly because of the complex interaction between bioreactor and microorganisms. However, classical techniques used for measuring local hydrodynamic properties such as single needle probes are mainly limited to two-phase flows. In this work it was developed and validated a new system, based on the customization of an optical probe initially designed in LEGI. The necessity o...

  12. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    2013-01-01

    Mobile probing is a method, developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time and space......). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings point...... to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face). The development...

  13. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    2012-01-01

    Mobile probing is a method, which has been developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time...... and space). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings...... point to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face...

  14. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    2012-01-01

    Mobile probing is a method, which has been developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time...... and space). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings...... point to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face...

  15. Robot-assisted three-dimensional registration for cochlear implant surgery using a common-path swept-source optical coherence tomography probe

    Science.gov (United States)

    Gurbani, Saumya S.; Wilkening, Paul; Zhao, Mingtao; Gonenc, Berk; Cheon, Gyeong Woo; Iordachita, Iulian I.; Chien, Wade; Taylor, Russell H.; Niparko, John K.; Kang, Jin U.

    2014-05-01

    Cochlear implantation offers the potential to restore sensitive hearing in patients with severe to profound deafness. However, surgical placement of the electrode array within the cochlea can produce trauma to sensorineural components, particularly if the initial turn of the cochlea is not successfully navigated as the array is advanced. In this work, we present a robot-mounted common-path swept-source optical coherence tomography endoscopic platform for three-dimensional (3-D) optical coherence tomography (OCT) registration and preoperative surgical planning for cochlear implant surgery. The platform is composed of a common-path 600-μm diameter fiber optic rotary probe attached to a five degrees of freedom robot capable of 1 μm precision movement. The system is tested on a dry fixed ex vivo human temporal bone, and we demonstrate the feasibility of a 3-D OCT registration of the cochlea to accurately describe the spatial and angular profiles of the canal formed by the scala tympani into the first cochlear turn.

  16. Testing an improved cymbal hydrophone%钹式水听器的改进和测试

    Institute of Scientific and Technical Information of China (English)

    陈晟; 林关成

    2009-01-01

    钹式水听器体积小,灵敏度高,但其接收性能不够稳定,接收频带较窄.为了克服这些弱点,对其结构进行改进.运用双片陶瓷并联代替单片陶瓷,并缩小陶瓷半径.再通过有限元仿真实验和水池实验,对改进前后的钹式水听器进行测试,结果表明,改进后的钹式水听器接收性能更加稳定,接收频带也明显增加,同时其灵敏度依然较高.%Cymbal hydrophones have small volume and high sensitivity, but their reception is not stable enough, and their reception is in too narrow a frequency band. In order to overcome these inadequacies, the structure of the cymbal hydrophone was improved. The single ceramic piezoelectric element was replaced with a double one, the radius of the ceramic piezoelectric element was reduced, and a parallel circuit was added. A static analysis of this new structure was developed, and then simulations were made of both the traditional and new hydropbone structure using finite element software. Tests were then conducted in a tank. The results showed that the improved hydrophone has reception in a wider frequency band, reception performance is stable within this frequency band, and sensitivity is still high.

  17. Optical probing of the metal-to-insulator transition in a two-dimensional high-mobility electron gas

    Energy Technology Data Exchange (ETDEWEB)

    Dionigi, F; Rossella, F; Bellani, V [Dipartimento di Fisica ' A Volta' and CNISM, Universita degli Studi di Pavia, 27100 Pavia (Italy); Amado, M [GISC and Departamento de Fisica de Materiales, Universidad Complutense, 28040 Madrid (Spain); Diez, E [Laboratorio de Bajas Temperaturas, Universidad de Salamanca, 37008 Salamanca (Spain); Kowalik, K [Laboratoire National des Champs Magnetiques Intenses, CNRS, 38042 Grenoble (France); Biasiol, G [Istituto Officina dei Materiali CNR, Laboratorio TASC, 34149 Trieste (Italy); Sorba, L, E-mail: vittorio.bellani@unipv.it [NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, 56126 Pisa (Italy)

    2011-06-15

    We study the quantum Hall liquid and the metal-insulator transition in a high-mobility two-dimensional electron gas, by means of photoluminescence and magnetotransport measurements. In the integer and fractional regime at {nu}>1/3, by analyzing the emission energy dispersion we probe the magneto-Coulomb screening and the hidden symmetry of the electron liquid. In the fractional regime above {nu}=1/3, the system undergoes metal-to-insulator transition, and in the insulating phase the dispersion becomes linear with evidence of an increased renormalized mass.

  18. Photoplastic near-field optical probe with sub-100 nm aperture made by replication from a nanomould

    NARCIS (Netherlands)

    Kim, G.M.; Kim, B.J.; Have, ten E.S.; Segerink, F.; Hulst, van N.F.; Brugger, J.

    2003-01-01

    Polymers have the ability to conform to surface contours down to a few nanometres. We studied the filling of transparent epoxy-type EPON SU-8 into nanoscale apertures made in a thin metal film as a new method for polymer/metal near-field optical structures. Mould replica processes combining silicon

  19. Probing formally forbidden optical transitions in PbSe nanocrystals by time- and energy-resolved transient absorption spectroscopy

    NARCIS (Netherlands)

    Schins, J.M.; Trinh, M.T.; Houtepen, A.J.; Siebbeles, L.D.A.

    2009-01-01

    The first two peaks of the optical extinction spectrum of PbSe nanocrystals in solution have been assigned in the literature to the 1Sh1Se and 1Ph1Pe transitions. In the present work we assign the transitions causing extinction in the energy region between these two lowest-energy peaks. Our femtosec

  20. A drug dissolution monitor employing multiple fiber optic probes and a UV/visible diode array spectrophotometer.

    Science.gov (United States)

    Chen, C S; Brown, C W

    1994-07-01

    A traditional dissolution pumping system was recently replaced with a fiber optic interface between the spectrometer and the samples. However, the system was limited to a single sample vessel. In this study, a dissolution testing system with six vessels connected to a diode array spectrometer via six optical fibers was investigated. A bifurcated fiber optic bundle was used to transfer the light from the source to the dissolution vessels and was networked so that spectra of each sample can be measured periodically. A full spectrum calibration method based on Principal Component Regression (PCR) was used to determine the concentrations of active ingredients and to account for interferences due to excipients in tablet formulations. Results on this new fiber optic interface system are compared with those obtained previously with the traditional pumping system. Standard errors of prediction are between 1.5 and 3.2% using cross-validation and between 1.1 and 1.7% for the direct validation of two active ingredients in two different drug formulations.

  1. Finite frequency P-wave traveltime measurements on ocean bottom seismometers and hydrophones in the western Indian Ocean

    Science.gov (United States)

    Tsekhmistrenko, Maria; Sigloch, Karin; Hosseini, Kasra; Barruol, Guilhem

    2016-04-01

    From 2011 to 2014, the RHUM-RUM project (Reunion Hotspot Upper Mantle - Reunions Unterer Mantel) instrumented a 2000x2000km2 area of Indian Ocean seafloor, islands and Madagascar with broadband seismometers and hydrophones. The central component was a 13-month deployment of 57 German and French Ocean Bottom Seismometers (OBS) in 2300-5600 m depth. This was supplemented by 2-3 year deployments of 37 island stations on Reunion, Mauritius, Rodrigues, the southern Seychelles, the Iles Eparses and southern Madagascar. Two partner projects contributed another 30+ stations on Madagascar. Our ultimate objective is multifrequency waveform tomography of the entire mantle column beneath the Reunion hotspot. Ideally we would use all passbands that efficiently transmit body waves but this meets practical limits in the noise characteristics of ocean-bottom recordings in particular. Here we present the preliminary data set of frequency-dependent P-wave traveltime measurements on seismometers and hydrophones, obtained by cross-correlation of observed with predicted waveforms. The latter are synthesized from fully numerical Green's functions and carefully estimated, broadband source time functions. More than 200 teleseismic events during the 13-month long deployment yielded usable P-waveform measurements. We present our methods and discuss data yield and quality of ocean-bottom versus land seismometers, and of OBS versus broadband hydrophones. Above and below the microseismic noise band, data yields are higher than within it, especially for OBS. The 48 German OBS, equipped with Guralp 60 s sensors, were afflicted by relatively high self-noise compared to the 9 French instruments equipped with Nanometrics Trillium 240 s sensors. The HighTechInc (model HTI-01 and HTI-04-PCA/ULF) hydrophones (100 s corner period) functioned particularly reliably but their waveforms are relatively more challenging to model due to reverberations in the water column. We obtain ~15000 combined cross

  2. Using Some Nanoparticles as Optical Probes for Optical Bioimaging%几种先进的光学纳米探针在光学生物诊疗中的应用

    Institute of Scientific and Technical Information of China (English)

    詹求强; 张欣; 李心; 何赛灵

    2015-01-01

    先进的光学纳米探针对于生物组织的光学成像、疾病的诊断和治疗具有巨大的促进作用,尤其是对于生物体分子水平活动的动态信息的深入了解。新型的光学探针如纳米金棒、上转换纳米颗粒和氧化石墨烯等,能克服传统探针的一些不足,具有较高的对比度、稳定性和生物兼容性,而且还拥有深层组织成像和实时动态成像的能力。本文对这些纳米光学探针的光学性质和优点进行了简要的介绍,并通过综述作者及其他研究者在过去几年的研究成果,总结这些先进的纳米探针在生物成像和医学诊断、治疗方面的应用,并展望其应用前景。%The employment of nanometric optical probes is powerful for bioimaging, disease diagnosis and therapy, es-pecially for the deep understanding of some dynamic biological processes at the molecular level. Optical probes such as gold nanorods (GNRs), upconversion nanoparticles (UCNPs) and graphene oxide (GO) can overcome many draw-backs of conventional optical agents. These nanoparticles possess high imaging contrast, stability and biocompatibility. Furthermor, they provide optical approaches for deep-tissue imaging and real-time dynamic imaging. In this review pa-per, the optical properties and advantages of these nanoparticles are briefly introduced, and some of their applications in optical bioimaging, diagnosis and therapy are summarized based on some of the research progress made by the authors and others. The prospects of their application are also discussed.

  3. Combined multi-modal photoacoustic tomography, optical coherence tomography (OCT) and OCT angiography system with an articulated probe for in vivo human skin structure and vasculature imaging.

    Science.gov (United States)

    Liu, Mengyang; Chen, Zhe; Zabihian, Behrooz; Sinz, Christoph; Zhang, Edward; Beard, Paul C; Ginner, Laurin; Hoover, Erich; Minneman, Micheal P; Leitgeb, Rainer A; Kittler, Harald; Drexler, Wolfgang

    2016-09-01

    Cutaneous blood flow accounts for approximately 5% of cardiac output in human and plays a key role in a number of a physiological and pathological processes. We show for the first time a multi-modal photoacoustic tomography (PAT), optical coherence tomography (OCT) and OCT angiography system with an articulated probe to extract human cutaneous vasculature in vivo in various skin regions. OCT angiography supplements the microvasculature which PAT alone is unable to provide. Co-registered volumes for vessel network is further embedded in the morphologic image provided by OCT. This multi-modal system is therefore demonstrated as a valuable tool for comprehensive non-invasive human skin vasculature and morphology imaging in vivo.

  4. Nanozeolite-LTL with Gd(III) deposited in the large and Eu(III) in the small cavities as a magnetic resonance optical imaging probe.

    Science.gov (United States)

    Mayer, Florian; Zhang, Wuyuan; Brichart, Thomas; Tillement, Olivier; Bonnet, Célia S; Tóth, Éva; Peters, Joop A; Djanashvili, Kristina

    2014-03-17

    The immense structural diversity of more than 200 known zeolites is the basis for the wide variety of applications of these fascinating materials ranging from catalysis and molecular filtration to agricultural uses. Despite this versatility, the potential of zeolites in medical imaging has not yet been much exploited. In this work a novel strategy is presented to selectively deposit different ions into distinct framework locations of zeolite-LTL (Linde type L) and it is demonstrated that the carefully ion-exchanged Gd/Eu-containing nanocrystals acquire exceptional magnetic properties in combination with enhanced luminescence. This smart exploitation of the framework structure yields the highest relaxivity density (13.7 s(-1)  L g(-1) at 60 MHz and 25 °C) reported so far for alumosilicates, rendering these materials promising candidates for the design of dual magnetic resonance/optical imaging probes, as demonstrated in preliminary phantom studies.

  5. Combined multi-modal photoacoustic tomography, optical coherence tomography (OCT) and OCT angiography system with an articulated probe for in vivo human skin structure and vasculature imaging

    Science.gov (United States)

    Liu, Mengyang; Chen, Zhe; Zabihian, Behrooz; Sinz, Christoph; Zhang, Edward; Beard, Paul C.; Ginner, Laurin; Hoover, Erich; Minneman, Micheal P.; Leitgeb, Rainer A.; Kittler, Harald; Drexler, Wolfgang

    2016-01-01

    Cutaneous blood flow accounts for approximately 5% of cardiac output in human and plays a key role in a number of a physiological and pathological processes. We show for the first time a multi-modal photoacoustic tomography (PAT), optical coherence tomography (OCT) and OCT angiography system with an articulated probe to extract human cutaneous vasculature in vivo in various skin regions. OCT angiography supplements the microvasculature which PAT alone is unable to provide. Co-registered volumes for vessel network is further embedded in the morphologic image provided by OCT. This multi-modal system is therefore demonstrated as a valuable tool for comprehensive non-invasive human skin vasculature and morphology imaging in vivo. PMID:27699106

  6. A novel interplanetary optical navigation algorithm based on Earth-Moon group photos by Chang'e-5T1 probe

    Science.gov (United States)

    Bu, Yanlong; Zhang, Qiang; Ding, Chibiao; Tang, Geshi; Wang, Hang; Qiu, Rujin; Liang, Libo; Yin, Hejun

    2017-02-01

    This paper presents an interplanetary optical navigation algorithm based on two spherical celestial bodies. The remarkable characteristic of the method is that key navigation parameters can be estimated depending entirely on known sizes and ephemerides of two celestial bodies, especially positioning is realized through a single image and does not rely on traditional terrestrial radio tracking any more. Actual Earth-Moon group photos captured by China's Chang'e-5T1 probe were used to verify the effectiveness of the algorithm. From 430,000 km away from the Earth, the camera pointing accuracy reaches 0.01° (one sigma) and the inertial positioning error is less than 200 km, respectively; meanwhile, the cost of the ground control and human resources are greatly reduced. The algorithm is flexible, easy to implement, and can provide reference to interplanetary autonomous navigation in the solar system.

  7. Detection of hydrofluoric acid by a SiO2 sol-gel coating fiber-optic probe based on reflection-based localized surface plasmon resonance.

    Science.gov (United States)

    Chen, I-Cherng; Lin, Shiu-Shiung; Lin, Tsao-Jen; Du, Je-Kang

    2011-01-01

    A novel fiber-optic probe based on reflection-based localized surface plasmon resonance (LSPR) was developed to quantify the concentration of hydrofluoric acid (HF) in aqueous solutions. The LSPR sensor was constructed with a gold nanoparticle-modified PMMA fiber, integrated with a SiO(2) sol-gel coating. This fiber-sensor was utilized to assess the relationship between HF concentration and SiO(2) sol-gel layer etching reduction. The results demonstrated the LSPR sensor was capable of detecting HF-related erosion of hydrofluoric acid solutions of concentrations ranging from 1% to 5% using Relative RI Change Rates. The development of the LSPR sensor constitutes the basis of a detector with significant sensitivity for practical use in monitoring HF solution concentrations.

  8. Intra-Tissue Pressure Measurement in Ex Vivo Liver Undergoing Laser Ablation with Fiber-Optic Fabry-Perot Probe.

    Science.gov (United States)

    Tosi, Daniele; Saccomandi, Paola; Schena, Emiliano; Duraibabu, Dinesh Babu; Poeggel, Sven; Leen, Gabriel; Lewis, Elfed

    2016-04-15

    We report the first-ever intra-tissue pressure measurement performed during 1064 nm laser ablation (LA) of an ex vivo porcine liver. Pressure detection has been performed with a biocompatible, all-glass, temperature-insensitive Extrinsic Fabry-Perot Interferometry (EFPI) miniature probe; the proposed methodology mimics in-vivo treatment. Four experiments have been performed, positioning the probe at different positions from the laser applicator tip (from 0.5 mm to 5 mm). Pressure levels increase during ablation time, and decrease with distance from applicator tip: the recorded peak parenchymal pressure levels range from 1.9 kPa to 71.6 kPa. Different pressure evolutions have been recorded, as pressure rises earlier in proximity of the tip. The present study is the first investigation of parenchymal pressure detection in liver undergoing LA: the successful detection of intra-tissue pressure may be a key asset for improving LA, as pressure levels have been correlated to scattered recurrences of tumors by different studies.

  9. Intra-Tissue Pressure Measurement in Ex Vivo Liver Undergoing Laser Ablation with Fiber-Optic Fabry-Perot Probe

    Directory of Open Access Journals (Sweden)

    Daniele Tosi

    2016-04-01

    Full Text Available We report the first-ever intra-tissue pressure measurement performed during 1064 nm laser ablation (LA of an ex vivo porcine liver. Pressure detection has been performed with a biocompatible, all-glass, temperature-insensitive Extrinsic Fabry-Perot Interferometry (EFPI miniature probe; the proposed methodology mimics in-vivo treatment. Four experiments have been performed, positioning the probe at different positions from the laser applicator tip (from 0.5 mm to 5 mm. Pressure levels increase during ablation time, and decrease with distance from applicator tip: the recorded peak parenchymal pressure levels range from 1.9 kPa to 71.6 kPa. Different pressure evolutions have been recorded, as pressure rises earlier in proximity of the tip. The present study is the first investigation of parenchymal pressure detection in liver undergoing LA: the successful detection of intra-tissue pressure may be a key asset for improving LA, as pressure levels have been correlated to scattered recurrences of tumors by different studies.

  10. Detection of early stages of dental caries by optical PNC diagnostics: comparison with visual inspection, dental probe, and x-ray methods

    Science.gov (United States)

    Masychev, Victor I.; Sokolovsky, Alexander A.; Kesler, Gaby

    2000-11-01

    In this research results of approbation of the optical PNC-method in dental clinic are presented. The PNC-method was used for diagnostics stages of caries (initial, moderate and deep). The variant of the PNC-method adapted for dental diagnosis is based on simultaneous analyses the following parameters by special algorithms: probing radiation, stimulated backscattering and autofluorescence of caries induced batteries. Analyze of informational signals show good correlation with tooth morphological structure and concentration of anaerobic microflora in hearth of caries lesion. Investigation was performed in vivo on 101 tooth in conditions of typical dental clinic. Comparison of the PNC-methods with visual inspection, dental probe and X-ray ones, which are widely used in clinical practice was made. Preliminary results showed high potential of usage of the PNC-method in clinical practice and more high probability of initial caries detection (up to 100%) in comparison with X-ray method (approximately 75%). In cases when X-ray diagnosed absence of initial caries, more sensitive the PNC-method detected initial caries in stage white lesion.

  11. On the interpretation of negative birefringence observed in strong-field optical pump-probe experiments: high-order Kerr and plasma grating effects

    CERN Document Server

    Karras, G; Houzet, J; Hertz, E; Billard, F; Lavorel, B; Faucher, O

    2013-01-01

    The analysis of negative birefringence optically induced in major air components (Loriot et al., [1, 2]) is revisited in light of the recently reported plasma grating-induced phase-shift effect predicted for strong field pump-probe experiments (Wahlstrand and Milchberg, [3]). The nonlinear birefrin- gence induced by a short and intense laser pulse in argon is measured by femtosecond time-resolved polarimetry. The experiments are performed with degenerate colors, where the pump and probe beam share the same spectrum, or with two different colors and non-overlapping spectra. The in- terpretation of the experimental results is substantiated using a numerical 3D+1 model accounting for nonlinear propagation effects, cross-beam geometry of the interacting laser pulses, and detec- tion technique. The model also includes the ionization rate of argon and high-order Kerr indices introduced by Loriot et al. enabling to assess the contribution of both terms to the observed effect. The results show that the ionization-ind...

  12. Use of NIRS technology with a remote reflectance fibre-optic probe for predicting mineral composition (Ca, K, P, Fe, Mn, Na, Zn), protein and moisture in alfalfa.

    Science.gov (United States)

    González-Martín, I; Hernández-Hierro, J M; González-Cabrera, J M

    2007-03-01

    In the present work we study the use of near-infrared spectroscopy (NIRS) technology together with a remote reflectance fibre-optic probe for the analysis of major (Ca, K, P) and minor (Fe, Mn, Na, Zn) elements, protein and moisture in alfalfa. The method allows immediate analysis of the alfalfa without prior sample treatment or destruction through direct application of the fibre-optic probe on ground samples in the case of the mineral composition and on-ground and compacted (baled) samples in the case of protein and humidity. The regression method employed was modified partial least-squares (MPLS). The calibration results obtained using samples of alfalfa allowed the determination of Ca, K, P, Fe, Mn, Na and Zn, with a standard error of prediction (SEP(C)) and a correlation coefficient (RSQ) expressed in mg/kg of alfalfa of 1.37x10(3) and 0.878 for Ca, 1.10x10(3) and 0.899 for K, 227 and 0.909 for P, 103 and 0.948 for Fe, 5.1 and 0.843 for Mn, 86.2 and 0.979 for Na, and of 1.9 and 0.853 for Zn, respectively. The SEP(C) and RSQ values (in %) for protein and moisture in ground samples were 0.548 and 0.871 and 0.150 and 0.981, respectively; while in the compacted samples they were 0.564 and 0.826 and 0.262 and 0.935, respectively. The prediction capacity of the model and the robustness of the method were checked in the external validation in alfalfa samples of unknown composition, and the results confirmed the suitability of the method.

  13. Joint analysis of refraction seismic survey with multilevel hydrophone measurement (application for detecting the high velocity thin lid); Kussekiho jishin tansa data to kochu hydrophone data no fukugo kaiseki no rei

    Energy Technology Data Exchange (ETDEWEB)

    Mori, S.; Harada, T.; Hayashi, K. [OYO Corp., Tokyo (Japan)

    1996-05-01

    During a refraction seismic survey conducted at a spot where a high-speed lava layer is supposedly concealed, the distribution of lava layer was estimated, and a composite analysis involving the vibration data received via hydrophones arranged in a bore hole was accomplished using a high-speed model based on an assumed geological section. The refraction survey centered on the bore hole and was accomplished using 250m-long traverse lines extending therefrom, one to the upstream and the other to the downstream of a river, producing a total length of 500m. The hydrophones were installed in the bore hole, and the measurement was carried out in an offset VSP-like observation pattern. In the analysis, the velocities obtained by the refraction survey and velocity logging were assigned to each layer on the basis of the assumed geological section for the construction of a velocity distribution model, which served as the early model for the repetition of calculation. Calculation was repeated with help of the said model, and a geological structure, capable of explaining the travel time data collected during the refraction survey and velocity logging, was successfully estimated. 1 ref., 5 figs.

  14. 光纤触发式测头及其性能测试研究%An optical fiber trigger probe and its performance test

    Institute of Scientific and Technical Information of China (English)

    韩欣; 林家春

    2012-01-01

    In order to solve the problem of the workpiece surface data point sampling of coordinate measuring machine and other precise instruments, the photoelectric technology and digital signal processing( DSP) technology were utilized to develop an optical fiber trigger probe. After the analysis of working principle of an optical fiber trigger probe,it was found that when the light beam was irradiated to the surface of the ball, the light intensity coupled into the receiving optical fibers distributed around the launching optical fiber was changed under the incident angle changed. Based on this phenomenon,a silicon PIN photodiode was adapted to transfer light intensity variation into electrical signal at the end of the receiving optical fibers. After the signal preprocessing,multiple signals' analog-to-digital conversion was conducted;then DSP was used to process the acquired signals,and a trigger pulse signal was sent out when operational results reached a threshold. Finally experiments were designed to test the pre-displacement and the undirectional repeatability. Experiments indicate that the pre-displacement is 0.97μm, and the unidirectional repeatability is 0.42 μm. The experimental results show that the probe is practical for measuring machines.%为解决三坐标测量机等精密仪器在被测工件表面数据点的采样问题,将光电技术和数字信号处理(DSP)技术应用到光纤触发式测头的研制中.分析了光纤触发式测头的工作原理;当光束照射到球的表面,随意入射角的变化,耦合入分布在发射光纤周围接收光纤的光强也会发生变化,基于这一现象,在接收光纤末端利用硅PIN光电二极管将光强的变化转化为电信号,在信号预处理之后,进行了多路信号模数转换;然后,利用DSP对采集到的多路信号进行运算处理,当运算结果达到设定阈值时发出触发脉冲信号;最后,通过实验对测头的预行程变动量和单向重复性精度进

  15. A Clicked Tetrathiafulvalene-oxyquinoline Dyad as an Optical and Electrochemical Zn2+ Probe%A Clicked Tetrathiafulvalene-oxyquinoline Dyad as an Optical and Electrochemical Zn2+ Probe

    Institute of Scientific and Technical Information of China (English)

    Zhao, Bangtun; Liu, Lianwei; Li, Xiaochuan; Qu, Guirong

    2012-01-01

    A novel clicked tetrathiafulvalene derivative 3 bearing two 8-oxyquinoline groups was synthesized for the selective detection of Zn2+ through optical and electrochemical changes. The addition of Zn2+ and Cd2+ induced a significant change in fluorescence intensity, which was attributable to the chelation-enhanced fluorescence effect from the oxyquinoline and 1,2,3-triazole rings. The electrochemical potentials of 3 in the presence of the Zn2+ were shifted toward more positive values relative to those of the other metal cations tested.

  16. Taking label-free optical spectroscopy techniques into the operating theatre: biopsy needles and surgical guidance probes (Conference Presentation)

    Science.gov (United States)

    Leblond, Frédéric

    2017-02-01

    Recent advances will be described relating to the development and clinical translation of optical spectroscopy techniques designed to guide surgical interventions in brain and prostate oncology applications. The use of molecular imaging guidance systems can enable true intra-operative tissue identification, increasing the effectiveness of cancer surgery and potentially positively impacting patient survival. Surgical resection is a fundamental cancer treatment, but its effectiveness is reduced by the inability to rapidly and accurately identify cancer margins. We will introduce a portable intraoperative label-free multimodal optical spectroscopy system combining intrinsic fluorescence, diffuse reflectance, and Raman spectroscopy that can identify cancer in situ during surgery. We will show that this on-line guidance system can detect primary cancer such as glioma as well as metastatic melanoma and cancer of the lung and colon with an accuracy, sensitivity, and specificity of 97%, 100%, and 93% respectively. Moreover, a method will be presented, along with preliminary tissue classification results, based on the interrogation of whole human prostates from prostatectomies. The development and in vivo validation of an optical brain needle biopsy instrument will be presented demonstrating its ability to detect bulk tumor using Raman spectroscopy with the goal of reducing the number of non-diagnostic samples during a procedure. The extraction of tissue can cause life-threatening hemorrhage because of significant blood vessel injury during the procedure. We will demonstrate that a sub-diffuse optical tomography technique integrated with a commercial biopsy needle can detect the presence of blood vessels to limit the hemorrhage risk.

  17. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    2013-01-01

    to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face). The development...

  18. Measurements of nonlinear lensing in a semiconductor disk laser gain sample under optical pumping and using a resonant femtosecond probe laser

    Science.gov (United States)

    Quarterman, A. H.; Mirkhanov, S.; Smyth, C. J. C.; Wilcox, K. G.

    2016-09-01

    Accurate characterizations of the nonlinear refractive index of semiconductor disk laser (SDL) gain samples are of critical importance for understanding the behavior of self-mode-locked SDLs. Here we describe measurements of nonlinear lensing in an SDL gain sample for a wide range of optical pump intensities and using a probe which is on resonance with the quantum wells in the SDL gain sample and whose intensity, pulse duration, and spot size are chosen to be similar to those reported in self-mode-locked SDLs. Under these conditions, we determine an effective value of the nonlinear refractive index, n2 = -6.5 × 10-13 cm2/W at zero pump intensity, and find that the value of n2 changes by less than 25% over the range of pump intensities studied. The nonlinear refractive index is measured using a variation on the well-established z-scan technique, which was modified to make it better suited to the measurement of optically pumped samples.

  19. NIRS measurement of tissue pH: optimizing small fiber optic probe designs with the aid of Monte-Carlo simulations

    Science.gov (United States)

    Khan, Tania; Soller, Babs R.

    2000-05-01

    Tissue pH electrodes have been used in research and in humans to evaluate various myocardial protection methods during heart surgery. Near IR spectroscopic measurement of myocardial tissue pH is a feasible, minimally invasive method that can be used to identify regional areas of ischemia and provide the surgeon with information continuously and postoperatively. Inhomogeneous, depth dependent tissue pH levels in ischemic myocardium make a robust in-vivo optical measurement challenging. Tissue heterogeneity requires a well-defined optical probe geometry capable of detecting light with adequate localization. Monte Carlo modeling of light propagation for purely scattering and relevant absorbing and scattering media were use4d to identify possible source-detector fiber separations for a matched boundary. In the region approximately 0.3 to 0.8 mm away from the source, the models demonstrated that minimization of the wavelength dependence of scattering is possible. Wavelength dependence is apparent at separations greater than approximately 1.2 mm. Adequate localization of NIR light is tissue is feasible within this source-detector separation range based on the simulations with hemoglobin as the only absorber. The application to a small fiber sensor's fabrication is discussed.

  20. Probing interstellar turbulence in cirrus with deep optical imaging: no sign of energy dissipation at 0.01 pc scale

    Science.gov (United States)

    Miville-Deschênes, M.-A.; Duc, P.-A.; Marleau, F.; Cuillandre, J.-C.; Didelon, P.; Gwyn, S.; Karabal, E.

    2016-08-01

    Diffuse Galactic light has been observed in the optical since the 1930s. We propose that, when observed in the optical with deep imaging surveys, it can be used as a tracer of the turbulent cascade in the diffuse interstellar medium (ISM), down to scales of about 1 arcsec. Here we present a power spectrum analysis of the dust column density of a diffuse cirrus at high Galactic latitude (l ≈ 198°, b ≈ 32°) as derived from the combination of a MegaCam g-band image, obtained as part of the MATLAS large programme at the CFHT, with Planck radiance and WISE 12 μm data. The combination of these three datasets have allowed us to compute the density power spectrum of the H i over scales of more than three orders of magnitude. We found that the density field is well described by a single power law over scales ranging from 0.01 to 50 pc. The exponent of the power spectrum, γ = -2.9 ± 0.1, is compatible with what is expected for thermally bi-stable and turbulent H i. We did not find any steepening of the power spectrum at small scales indicating that the typical scale at which turbulent energy is dissipated in this medium is smaller than 0.01 pc. The ambipolar diffusion scenario that is usually proposed as the main dissipative agent, is consistent with our data only if the density of the cloud observed is higher than the typical values assumed for the cold neutral medium gas. We discuss the new avenue offered by deep optical imaging surveys for the study of the low density ISM structure and turbulence.

  1. Fabrication of valine-functionalized graphene quantum dots and its use as a novel optical probe for sensitive and selective detection of Hg2 +

    Science.gov (United States)

    Xiaoyan, Zhou; Zhangyi, Li; Zaijun, Li

    2017-01-01

    The functionalization of graphene quantum dots has become a powerful method to modulate its chemical, electronic and optical properties for various applications. In the study, we reported a facile synthesis of valine-functionalized graphene quantum dots (Val-GQDs) and its use as a novel fluorescent probe for optical detection of Hg2 +. Herein, Val-GQDs was synthesized by the thermal pyrolysis of citric acid and valine. The resulting Val-GQDs has an average size of 3 nm and the edge of graphene sheets contains the rich of hydrophilic groups, leading to a high water-solubility. Compared to the GQDs prepared by thermal pyrolysis of citric acid, Val-GQDs exhibits a stronger fluorescence (> 10-fold) and better photostability (> 4-fold). Interestingly, the existence of valine moieties in the Val-GQDs results in a more sensitive fluorescent response to Hg2 +. The fluorescent signal will linearly decrease with the increase of Hg2 + concentration in the range from 0.8 nM to 1 μM with the correlation coefficient of 0.992. The detection limit is 0.4 nM (S/N = 3), which the sensitivity is > 14-fold that of GQDs. The analytical method provides the prominent advantage of sensitivity, selectivity and stability. It has been successfully applied in the optical detection of Hg2 + in real water samples. The study also provides a promising approach for the design and synthesis of functionalized GQDs to meet the needs of further applications in sensing and catalysis.

  2. Four dimensional hybrid ultrasound and optoacoustic imaging via passive element optical excitation in a hand-held probe

    Energy Technology Data Exchange (ETDEWEB)

    Fehm, Thomas Felix; Razansky, Daniel, E-mail: dr@tum.de [Institute for Biological and Medical Imaging (IBMI), Helmholtz Zentrum München, Neuherberg (Germany); Faculty of Medicine, Technische Universität München, Munich (Germany); Deán-Ben, Xosé Luís [Institute for Biological and Medical Imaging (IBMI), Helmholtz Zentrum München, Neuherberg (Germany)

    2014-10-27

    Ultrasonography and optoacoustic imaging share powerful advantages related to the natural aptitude for real-time image rendering with high resolution, the hand-held operation, and lack of ionizing radiation. The two methods also possess very different yet highly complementary advantages of the mechanical and optical contrast in living tissues. Nonetheless, efficient integration of these modalities remains challenging owing to the fundamental differences in the underlying physical contrast, optimal signal acquisition, and image reconstruction approaches. We report on a method for hybrid acquisition and reconstruction of three-dimensional pulse-echo ultrasound and optoacoustic images in real time based on passive ultrasound generation with an optical absorber, thus avoiding the hardware complexity of active ultrasound generation. In this way, complete hybrid datasets are generated with a single laser interrogation pulse, resulting in simultaneous rendering of ultrasound and optoacoustic images at an unprecedented rate of 10 volumetric frames per second. Performance is subsequently showcased in phantom experiments and in-vivo measurements from a healthy human volunteer, confirming general clinical applicability of the method.

  3. Probing interstellar turbulence in cirrus with deep optical imaging: no sign of energy dissipation at 0.01 pc scale

    CERN Document Server

    Miville-Deschenes, M -A; Marleau, F; Cuillandre, J -C; Didelon, P; Gwyn, S; Karabal, E

    2016-01-01

    Diffuse Galactic light (DGL) has been observed in the optical since the 1930s. We propose that, when observed in the optical with deep imaging surveys, it can be used as a tracer of the turbulent cascade in the diffuse interstellar medium, down to scales of about 1 arcsec. Here we present a power spectrum analysis of the dust column density of a diffuse cirrus at high Galactic latitude (l ~ 198 deg, b ~ 32 deg) as derived from the combination of a MegaCam g-band image, obtained as part of the MATLAS Large Programme at the CFHT, with Planck Radiance and Wise 12 micron data. The combination of these three datasets allowed us to compute the density power spectrum of the HI over more than three orders of magnitudes in scales. We found that the density field is well described by a single power law over scales ranging from 0.01 to 50 pc. The exponent of the power spectrum, gamma=-2.9 +- 0.1, is compatible with what is expected for thermally bi-stable and turbulent HI. We did not find any steepening of the power spe...

  4. Optical interference probe of biofilm hydrology: label-free characterization of the dynamic hydration behavior of native biofilms

    Science.gov (United States)

    McDonough, Richard T.; Zheng, Hewen; Alila, Mercy A.; Goodisman, Jerry; Chaiken, Joseph

    2017-03-01

    Biofilm produced by Escherichia coli (E. coli) or Pseudomonas aeruginosa (P. aeruginosa) on quartz or polystyrene is removed from the culture medium and drained. Observed optical interference fringes indicate the presence of a layer of uniform thickness with refractive index different from air-dried biofilm. Fringe wavelengths indicate that layer optical thickness is biofilm as measured by confocal Raman microscopy or fluorescence imaging of the bacteria. Raman shows that films have an alginate-like carbohydrate composition. Fringe amplitudes indicate that the refractive index of the interfering layer is higher than dry alginate. Drying and rehydration nondestructively thins and restores the interfering layer. The strength of the 1451-nm near infrared water absorption varies in unison with thickness. Absorption and layer thickness are proportional for films with different bacteria, substrates, and growth conditions. Formation of the interfering layer is general, possibly depending more on the chemical nature of alginate-like materials than bacterial processes. Films grown during the exponential growth phase produce no observable interference fringes, indicating requirements for layer formation are not met, possibly reflecting bacterial activities at that stage. The interfering layer might provide a protective environment for bacteria when water is scarce.

  5. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Ninth Edition Optics: Ninth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommen

  6. Nonlinear optical processes at quadrupole polariton resonance in Cu2O as probed by a Z-scan technique

    Science.gov (United States)

    Mani, S.; Jang, J. I.; Ketterson, J. B.

    2010-09-01

    Employing a modified Z-scan technique at 2 K, we monitor not only the fundamental (ω) but also the frequency-doubled (2ω) and tripled (3ω) Z-scan responses in Cu2O when the input laser frequency ω is tuned to the two-photon quadrupole polariton resonance. The Z-scan response at ω allows us to accurately estimate the absolute number of polaritons generated via two-photon absorption. A striking dip is observed near the 2ω Z-scan focus which basically arises from Auger-type recombination of polaritons. Under high excitation levels, the 3ω Z-scan shows strong third harmonic generation. Based on the nonlinear optical parameters determined, we estimate the experimental polariton density achievable and propose a direction for polariton-based Bose-Einstein condensation in Cu2O .

  7. Optical imaging of disseminated leukemia models in mice with near-infrared probe conjugated to a monoclonal antibody.

    Directory of Open Access Journals (Sweden)

    Sabrina Pesnel

    Full Text Available BACKGROUND: The assessment of anticancer agents to treat leukemia needs to have animal models closer to the human pathology such as implantation in immunodeficient mice of leukemic cells from patient samples. A sensitive and early detection of tumor cells in these orthotopic models is a prerequisite for monitoring engraftment of leukemic cells and their dissemination in mice. Therefore, we developed a fluorescent antibody based strategy to detect leukemic foci in mice bearing patient-derived leukemic cells using fluorescence reflectance imaging (FRI to determine when to start treatments with novel antitumor agents. METHODS: Two mAbs against the CD44 human myeloid marker or the CD45 human leukocyte marker were labeled with Alexa Fluor 750 and administered to leukemia-bearing mice after having verified the immunoreactivity in vitro. Bioluminescent leukemic cells (HL60-Luc were used to compare the colocalization of the fluorescent mAb with these cells. The impact of the labeled antibodies on disease progression was further determined. Finally, the fluorescent hCD45 mAb was tested in mice engrafted with human leukemic cells. RESULTS: The probe labeling did not modify the immunoreactivity of the mAbs. There was a satisfactory correlation between bioluminescence imaging (BLI and FRI and low doses of mAb were sufficient to detect leukemic foci. However, anti-hCD44 mAb had a strong impact on the tumor proliferation contrary to anti-hCD45 mAb. The use of anti-hCD45 mAb allowed the detection of leukemic patient cells engrafted onto NOD/SCID mice. CONCLUSIONS: A mAb labeled with a near infrared fluorochrome is useful to detect leukemic foci in disseminated models provided that its potential impact on tumor proliferation has been thoroughly documented.

  8. In situ optical sequencing and structure analysis of a trinucleotide repeat genome region by localization microscopy after specific COMBO-FISH nano-probing

    Science.gov (United States)

    Stuhlmüller, M.; Schwarz-Finsterle, J.; Fey, E.; Lux, J.; Bach, M.; Cremer, C.; Hinderhofer, K.; Hausmann, M.; Hildenbrand, G.

    2015-10-01

    Trinucleotide repeat expansions (like (CGG)n) of chromatin in the genome of cell nuclei can cause neurological disorders such as for example the Fragile-X syndrome. Until now the mechanisms are not clearly understood as to how these expansions develop during cell proliferation. Therefore in situ investigations of chromatin structures on the nanoscale are required to better understand supra-molecular mechanisms on the single cell level. By super-resolution localization microscopy (Spectral Position Determination Microscopy; SPDM) in combination with nano-probing using COMBO-FISH (COMBinatorial Oligonucleotide FISH), novel insights into the nano-architecture of the genome will become possible. The native spatial structure of trinucleotide repeat expansion genome regions was analysed and optical sequencing of repetitive units was performed within 3D-conserved nuclei using SPDM after COMBO-FISH. We analysed a (CGG)n-expansion region inside the 5' untranslated region of the FMR1 gene. The number of CGG repeats for a full mutation causing the Fragile-X syndrome was found and also verified by Southern blot. The FMR1 promotor region was similarly condensed like a centromeric region whereas the arrangement of the probes labelling the expansion region seemed to indicate a loop-like nano-structure. These results for the first time demonstrate that in situ chromatin structure measurements on the nanoscale are feasible. Due to further methodological progress it will become possible to estimate the state of trinucleotide repeat mutations in detail and to determine the associated chromatin strand structural changes on the single cell level. In general, the application of the described approach to any genome region will lead to new insights into genome nano-architecture and open new avenues for understanding mechanisms and their relevance in the development of heredity diseases.

  9. A subcutaneous Raman needle probe.

    Science.gov (United States)

    Day, John C C; Stone, Nicholas

    2013-03-01

    Raman spectroscopy is a powerful tool for studying the biochemical composition of tissues and cells in the human body. We describe the initial results of a feasibility study to design and build a miniature, fiber optic probe incorporated into a standard hypodermic needle. This probe is intended for use in optical biopsies of solid tissues to provide valuable information of disease type, such as in the lymphatic system, breast, or prostate, or of such tissue types as muscle, fat, or spinal, when identifying a critical injection site. The optical design and fabrication of this probe is described, and example spectra of various ex vivo samples are shown.

  10. Seismicity And Accretion Process Along The North Mid-Atlantic Ridge From The SIRENA Autonomous Hydrophone Data

    Science.gov (United States)

    Perrot, J.; Goslin, J.; Dziak, R. P.; Haxel, J. H.; Maia, M. A.; Tisseau, C.; Royer, J.

    2009-12-01

    The seismicity of the North Atlantic Ocean was recorded by the SIRENA array of 6 autonomous underwater hydrophones (AUH) moored within the SOFAR channel on the flanks of the Mid-Atlantic Ridge (MAR). The instruments were deployed north of the Azores Plateau between 40° and 50°N from June 2002 to September 2003. The low attenuation properties of the SOFAR channel for earthquake T-wave propagation result in a detection threshold reduction to a magnitude completeness level (Mc) of ~2.8, to be compared to a Mc~4.7 for MAR events recorded by land-based seismic networks. A spatio-temporal analysis was performed over the 1696 events localized inside the SIRENA array. For hydrophone-derived catalogs, the acoustic magnitude, or Source Level (SL), is used as a measure of earthquake size. The ''source level completeness'', above which the data set is complete, is SLc=208 dB. The SIRENA catalog was searched for swarms using the cluster software of the SEISAN distribution. A minimum SL of 210 dB was chosen to detect a possible mainshock, and all subsequent events within 40 days following the possible mainshock, located within a radius of 15 km from the mainshock were considered as events of the swarm. 15 km correspond to the maximum fault length in a slow-ridge context. 11 swarms with more than 15 events were detected along the MAR between 40°et 50°N during the SIRENA deployment. The maximum number of earthquakes in a swarm is 40 events. The SL vs. time distribution within each swarm allowed a first discrimination between the swarms occurring in a tectonic context and those which can be attributed to volcanic processes, the latter showing a more constant SL vs. time distribution. Moreover, the swarms occurring in a tectonic context show a "mainshock-afterschock" distribution of the cumulative number of events vs. time, fitting a Modified Omori Law. The location of tectonic and volcanic swarms correlates well with regions where a positive and negative Mantle Bouguer

  11. Probing into the aging dynamics of biomass burning aerosol by using satellite measurements of aerosol optical depth and carbon monoxide

    Science.gov (United States)

    Konovalov, Igor B.; Beekmann, Matthias; Berezin, Evgeny V.; Formenti, Paola; Andreae, Meinrat O.

    2017-04-01

    Carbonaceous aerosol released into the atmosphere from open biomass burning (BB) is known to undergo considerable chemical and physical transformations (aging). However, there is substantial controversy about the nature and observable effects of these transformations. A shortage of consistent observational evidence on BB aerosol aging processes under different environmental conditions and at various temporal scales hinders development of their adequate representations in chemistry transport models (CTMs). In this study, we obtain insights into the BB aerosol dynamics by using available satellite measurements of aerosol optical depth (AOD) and carbon monoxide (CO). The basic concept of our method is to consider AOD as a function of the BB aerosol photochemical age (that is, the time period characterizing the exposure of BB aerosol emissions to atmospheric oxidation reactions) predicted by means of model tracers. We evaluate the AOD enhancement ratio (ER) defined as the ratio of optical depth of actual BB aerosol with respect to that of a modeled aerosol tracer that is assumed to originate from the same fires as the real BB aerosol but that is not affected by any aging processes. To limit possible effects of model transport errors, the AOD measurements are normalized to CO column amounts that are also retrieved from satellite measurements. The method is applied to the analysis of the meso- and synoptic-scale evolution of aerosol in smoke plumes from major wildfires that occurred in Siberia in summer 2012. AOD and CO retrievals from MODIS and IASI measurements, respectively, are used in combination with simulations performed with the CHIMERE CTM. The analysis indicates that aging processes strongly affected the evolution of BB aerosol in the situation considered, especially in dense plumes (with spatial average PM2. 5 concentration exceeding 100 µg m-3). For such plumes, the ER is found to increase almost 2-fold on the scale of ˜ 10 h of daytime aerosol evolution

  12. T-phase and tsunami pressure waveforms recorded by near-source IMS water-column hydrophone triplets during the 2015 Chile earthquake

    Science.gov (United States)

    Matsumoto, H.; Haralabus, G.; Zampolli, M.; Özel, N. M.

    2016-12-01

    Underwater acoustic signal waveforms recorded during the 2015 Chile earthquake (Mw 8.3) by the hydrophones of hydroacoustic station HA03, located at the Juan Fernandez Islands, are analyzed. HA03 is part of the Comprehensive Nuclear-Test-Ban Treaty International Monitoring System. The interest in the particular data set stems from the fact that HA03 is located only approximately 700 km SW from the epicenter of the earthquake. This makes it possible to study aspects of the signal associated with the tsunamigenic earthquake, which would be more difficult to detect had the hydrophones been located far from the source. The analysis shows that the direction of arrival of the T phase can be estimated by means of a three-step preprocessing technique which circumvents spatial aliasing caused by the hydrophone spacing, the latter being large compared to the wavelength. Following this preprocessing step, standard frequency-wave number analysis (F-K analysis) can accurately estimate back azimuth and slowness of T-phase signals. The data analysis also shows that the dispersive tsunami signals can be identified by the water-column hydrophones at the time when the tsunami surface gravity wave reaches the station.

  13. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Eighth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommended for engineering st

  14. Effects of nicotinamide and carbogen on oxygenation in human tumor xenografts measured with luminescense based fiber-optic probes.

    Science.gov (United States)

    Bussink, J; Kaanders, J H; Strik, A M; van der Kogel, A J

    2000-10-01

    In head and neck cancer, addition of both carbogen breathing and nicotinamide to accelerated fractionated radiotherapy showed increased loco-regional control rates. An assay based on the measurement of changes in tumor pO(2) in response to oxygenation modification could be helpful for selecting patients for these new treatment approaches. The fiber-optic oxygen-sensing device, OxyLite, was used to measure changes in pO(2), at a single position in tumors, after treatment with nicotinamide and carbogen in three human xenograft tumor lines with different vascular architecture and hypoxic patterns. Pimonidazole was used as a marker of hypoxia and was analyzed with a digital image processing system. At the position of pO(2) measurement, half of the tumors showed a local increase in pO(2) after nicotinamide administration. Steep increases in pO(2) were measured in most tumors during carbogen breathing although the increase was less pronounced in tumor areas with a low pre-treatment pO(2). A trend towards a faster local response to carbogen breathing for nicotinamide pre-treated tumors was found in all three lines. There were significant differences in hypoxic fractions, based on pimonidazole binding, between the three tumor lines. There was no correlation between hypoxic marker binding and the response to carbogen breathing. Temporal changes in local pO(2) can be measured with the OxyLite. This system was used to quantitate the effects of oxygen modifying treatments. Rapid increases in pO(2) during carbogen breathing were observed in most tumor areas. The locally measured response to nicotinamide was smaller and more variable. Bio-reductive hypoxic cell marker binding in combination with OxyLite pO(2) determination gives spatial information about the distribution patterns of tumor hypoxia at the microscopic level together with the possibility to continuously measure changes in pO(2) in specific tumor areas.

  15. Self-excited multi-scale skin vibrations probed by optical tracking micro-motions of tracers on arms

    Science.gov (United States)

    Chen, Wei-Chia; Chen, Hsiang-Ying; Chen, Yu-Sheng; Tian, Yong; I, Lin

    2017-07-01

    The self-excited multi-scale mechanical vibrations, their sources and their mutual coupling of different regions on the forearms of supine subjects, are experimentally investigated, using a simple noncontact method, optical video microscopy, which provides 1 μm and 25 ms spatiotemporal resolutions. It is found that, in proximal regions far from the radial artery, the vibrations are the global vibrations of the entire forearm excited by remote sources, propagating through the trunk and the limb. The spectrum is mainly composed of peaks of very low frequency motion (down to 0.05 Hz), low frequency respiration modes, and heartbeat induced modes (about 1 Hz and its harmonics), standing out of the spectrum floor exhibiting power law decay. The nonlinear mode-mode coupling leads to the cascaded modulations of higher frequency modes by lower frequency modes. The nearly identical waveforms without detectable phase delays for a pair of signals along or transverse to the meridian of regions far away from the artery rule out the detectable contribution from the propagation of Qi, some kind of collective excitation which more efficiently propagates along meridians, according to the Chinese medicine theory. Around the radial artery, in addition to the global vibration, the local vibration spectrum shows very slow breathing type vibration around 0.05 Hz, and the artery pulsation induced fundamental and higher harmonics with descending intensities up to the fifth harmonics, standing out of a flat spectrum floor. All the artery pulsation modes are also modulated by respiration and the very slow vibration.

  16. Sol-gel based optical sensor for determination of Fe (II): a novel probe for iron speciation.

    Science.gov (United States)

    Samadi-Maybodi, Abdolraouf; Rezaei, Vida; Rastegarzadeh, Saadat

    2015-02-05

    A highly selective optical sensor for Fe (II) ions was developed based on entrapment of a sensitive reagent, 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), in a silica sol-gel thin film coated on a glass substrate. The thin films fabricated based on tetraethoxysilane (TEOS) as precursor, sol-gel pH∼3, water:alkoxyde ratio of 4:1 and TPTZ concentration of 0.112 mol L(-1). The influence of sol-gel parameters on sensing behavior of the fabricated sensor was also investigated. The fabricated sensor can be used for determination of Fe (II) ion with an outstanding high selectivity over a dynamic range of 5-115 ng mL(-1) and a detection limit of 1.68 ng mL(-1). It also showed reproducible results with relative standard deviation of 3.5% and 1.27% for 10 and 90 ng mL(-1) of Fe (II), respectively, along with a fast response time of ∼120 s. Total iron also was determined after reduction of Fe (III) to Fe (II) using ascorbic acid as reducing agent. Then, the concentration of Fe (III) was calculated by subtracting the concentration of Fe (II) from the total iron concentration. Interference studies showed a good selectivity for Fe (II) with trapping TPTZ into sol-gel matrix and appropriately adjusting the structure of doped sol-gel. The sensor was compared with other sensors and was applied to determine iron in different water samples with good results.

  17. Optically probing Al—O and O—H vibrations to characterize water adsorption and surface reconstruction on α-alumina: An experimental and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Yujin, E-mail: tong@fhi-berlin.mpg.de; Kirsch, Harald; Wolf, Martin; Campen, R. Kramer, E-mail: campen@fhi-berlin.mpg.de [Fritz Haber Institute of the Max Planck Society, 14195 Berlin (Germany); Wirth, Jonas; Saalfrank, Peter [Institute of Chemistry, University of Potsdam, 14476 Potsdam OT Golm (Germany)

    2015-02-07

    Oxide/water interfaces are ubiquitous in a wide variety of applications and the environment. Despite this ubiquity, and attendant decades of study, gaining molecular level insight into water/oxide interaction has proven challenging. In part, this challenge springs from a lack of tools to concurrently characterize changes in surface structure (i.e., water/oxide interaction from the perspective of the solid) and O—H population and local environment (i.e., water/oxide interaction from the water perspective). Here, we demonstrate the application of surface specific vibrational spectroscopy to the characterization of the interaction of the paradigmatic α-Al{sub 2}O{sub 3}(0001) surface and water. By probing both the interfacial Al—O (surface phonon) and O—H spectral response, we characterize this interaction from both perspectives. Through electronic structure calculation, we assign the interfacial Al—O response and rationalize its changes on surface dehydroxylation and reconstruction. Because our technique is all-optical and interface specific, it is equally applicable to oxide surfaces in vacuum, ambient atmospheres and at the solid/liquid interface. Application of this approach to additional alumina surfaces and other oxides thus seems likely to significantly expand our understanding of how water meets oxide surfaces and thus the wide variety of phenomena this interaction controls.

  18. Probing optical band gaps at nanoscale from tetrahedral cation vacancy defects and variation of cation ordering in NiCo2O4 epitaxial thin films

    Science.gov (United States)

    Dileep, K.; Loukya, B.; Silwal, P.; Gupta, A.; Datta, R.

    2014-10-01

    High resolution electron energy loss spectroscopy (HREELS) is utilized to probe the optical band gaps at the nanoscale in epitaxial NiCo2O4 (NCO) thin films with different structural order (cation/charge). The structure of NCO deviates from the ideal inverse spinel (non-magnetic and insulating) for films grown at higher temperatures (>500 °C) towards a mixed cation structure (magnetic with metallic conductivity) at lower deposition temperatures (<450 °C). This significantly modifies the electronic structure as well as the nature of the band gap of the material. Nanoscale regions with unoccupied tetrahedral A site cations are additionally observed in all the samples and direct measurement from such areas reveals considerably lower band gap values as compared to the ideal inverse spinel and mixed cation configurations. Experimental values of band gaps have been found to be in good agreement with the theoretical mBJLDA exchange potential based calculated band gaps for various cation ordering and consideration of A site cation vacancy defects. The origin of rich variation in cation ordering observed in this system is discussed.

  19. Development and evaluation of fiber optic probe-based helium-neon low-level laser therapy system for tissue regeneration--an in vivo experimental study.

    Science.gov (United States)

    Prabhu, Vijendra; Rao, Satish B S; Rao, Nageshwara B; Aithal, Kiran B; Kumar, Pramod; Mahato, Krishna K

    2010-01-01

    We report the design and development of an optical fiber probe-based Helium-Neon (He-Ne) low-level laser therapy system for tissue regeneration. Full thickness excision wounds on Swiss albino mice of diameter 15 mm were exposed to various laser doses of 1, 2, 3, 4, 6, 8 and 10 J cm(-2) of the system with appropriate controls, and 2 J cm(-2) showing optimum healing was selected. The treatment schedule for applying the selected laser dose was also standardized by irradiating the wounds at different postwounding times (0, 24 and 48 h). The tissue regeneration potential was evaluated by monitoring the progression of wound contraction and mean wound healing time along with the hydroxyproline and glucosamine estimation on wound ground tissues. The wounds exposed to 2 J cm(-2) immediately after wounding showed considerable contraction on days 5, 9, 12, 14, 16 and 19 of postirradiation compared with the controls and other treatment schedules, showing significant (P < 0.001) decrease in the healing time. A significant increase in hydroxyproline and glucosamine levels was observed for the 2 J cm(-2) irradiation group compared with the controls and other treatment groups. In conclusion, the wounds treated with 2 J cm(-2) immediately after the wounding show better healing compared with the controls.

  20. Optical probes of symmetry breaking in magnetic and superconducting BaFe2(As1-xPx)2

    Science.gov (United States)

    Orenstein, Joseph

    The discovery of iron pnictide superconductors has opened promising new directions in the effort to fully understand the phenomenon of high-Tc, with a focus on the connections between superconductivity, magnetism, and electronic nematicity. The BaFe2(As1-xPx)2 (P:Ba122) system in particular has received attention because isovalent substitution of As for P generates less disorder than doping on the Fe site. The phase diagram of P:Ba122 is characterized by a line of simultaneous antiferromagnetic (AF) and tetragonal-to-orthorhombic transitions, Ts (x) , that penetrates the superconducting dome at x =0.28, just below optimal doping (xopt = 0.30). In this work, we use spatially-resolved optical polarimetry and photomodulated reflectance to detect linear birefringence and therefore breaking of 4-fold rotational (C4) symmetry. In underdoped (xTsand grows continuously with decreasing T . The birefringence is unidirectional in a large (300 μm x300 μm) field of view, suggesting that C4 breaking in this range of T is caused by residual strain that couples to a diverging nematic susceptibility. Birefringence maps just below Ts (x) show the appearance of domains, indicating the onset of spontaneous symmetry breaking to an AF ground state. Surprisingly, in samples with x>0.28, in which the low T phase is superconducting/ tetragonal rather than AF/orthorhombic, C4 breaking is observed as well, with an abrupt onset and domain formation at 55 K. We tentatively associate these features with a transition to an AF phase induced by residual strain, as previously proposed [H.-H. Kuo et al. Phys. Rev. B86, 134507 (2012)] to account for structure in resistivity vs. T. Time-resolved photomodulation allow us to follow the amplitude of the AF order with time following pulsed photoexcitation. Below Tc the AF order at first weakens , but then strengthens in response to the photoinduced weakening of superconductivity. This complex time evolution is accounted for quantitatively by a model