Sample records for based optical coherence

  1. Integrated-optics-based optical coherence tomography

    NARCIS (Netherlands)

    Nguyen, D.V.


    Optical coherence tomography (OCT) is a high resolution, imaging technique that has developed over the last 20 years from a complicated laboratory setup into a ready-to-use commercially available device. Instead of using electronic time gating as being used by ultrasound (US) imaging, in OCT, the op

  2. Optical Microangiography Based on Optical Coherence Tomography (United States)

    Reif, Roberto; Wang, Ruikang K.

    Proper homeostasis regulation of in vivo biological systems requires microvascular blood perfusion, which is the process of delivering blood into the tissue's capillary beds. Abnormal tissue vascularization has been associated with various diseases such as cancer, diabetes, neurological disorders, wounds, and inflammation. Understanding the changes in the vascular network or microangiography will have an important role in determining the causes and developing potential treatments for these diseases. Optical coherence tomography (OCT) is a noninvasive method for imaging three-dimensional biological tissues with high resolution (~10 µm) and without requiring the use of contrast agents. In this chapter we review several techniques for using OCT to determine blood flow velocities and the vessel morphology (optical microangiography). Different techniques will be discussed with a brief explanation of their limitations. Also, methods for quantifying these images are presented, as well as the depiction of several applications.

  3. Fiber optic based optical coherence tomography (OCT) for dental applications

    Energy Technology Data Exchange (ETDEWEB)

    Everett, M. J., LLNL


    We have developed a hand-held fiber optic based optical coherence tomography (OCT) system for scanning of the oral cavity We have produced, using this scanning device, in viva cross-sectional images of hard and soft dental tissues in human volunteers Clinically relevant anatomical structures, including the gingival margin, periodontal sulcus, and dento-enamel junction, were visible in all the images The dento-enamel junction and the alveolar bone were identifiable in approximately two thirds of the images These images represent, to our knowledge, the first in viva OCT images of human dental tissue.

  4. Amplifier Noise Based Optical Steganography with Coherent Detection (United States)

    Wu, Ben; Chang, Matthew P.; Caldwell, Naomi R.; Caldwell, Myles E.; Prucnal, Paul R.


    We summarize the principle and experimental setup of optical steganography based on amplified spontaneous emission (ASE) noise. Using ASE noise as the signal carrier, optical steganography effectively hides a stealth channel in both the time domain and the frequency domain. Coherent detection is used at the receiver of the stealth channel. Because ASE noise has short coherence length and random phase, it only interferes with itself within a very short range. Coherent detection requires the stealth transmitter and stealth receiver to precisely match the optical delay,which generates a large key space for the stealth channel. Several methods to further improve optical steganography, signal to noise ratio, compatibility with the public channel, and applications of the stealth channel are also summarized in this review paper.

  5. Gabor-based fusion technique for Optical Coherence Microscopy. (United States)

    Rolland, Jannick P; Meemon, Panomsak; Murali, Supraja; Thompson, Kevin P; Lee, Kye-sung


    We recently reported on an Optical Coherence Microscopy technique, whose innovation intrinsically builds on a recently reported - 2 microm invariant lateral resolution by design throughout a 2 mm cubic full-field of view - liquid-lens-based dynamic focusing optical probe [Murali et al., Optics Letters 34, 145-147, 2009]. We shall report in this paper on the image acquisition enabled by this optical probe when combined with an automatic data fusion method developed and described here to produce an in-focus high resolution image throughout the imaging depth of the sample. An African frog tadpole (Xenopus laevis) was imaged with the novel probe and the Gabor-based fusion technique, demonstrating subcellular resolution in a 0.5 mm (lateral) x 0.5 mm (axial) without the need, for the first time, for x-y translation stages, depth scanning, high-cost adaptive optics, or manual intervention. In vivo images of human skin are also presented.

  6. High performance fiber-based optical coherent detection (United States)

    Chen, Youming

    The sensitivity of signal detection is of major interest for optical high speed communication systems and LIght Detection And Ranging (lidar) systems. Sensitive receivers in fiber-optical networks can reduce transmitter power or amplifier amplification requirements and extend link spans. High receiver sensitivity allows links to be established over long distances in deep space satellite communication systems and large atmospheric attenuation to be overcome in terrestrial free space communications. For lidar systems, the sensitivity of signal detection determines how far and how accurately the lidar can detect the remote objects. Optical receivers employ either coherent or direct detection. In addition to amplitude, coherent detection extracts frequency and phase information from received signals, whereas direct detection extracts the received pulse amplitude only. In theory, coherent detection should yield the highest receiver sensitivity. Another possible technique to improve detection sensitivity is to employ a fiber preamplifier. This technique has been successfully demonstrated in direct detection systems but not in the coherent detection systems. Due to the existence of amplified spontaneous emission (ASE) inside the amplifier, the sensitivity of coherent detection varies with the data rate or pulse rate. For this reason, optically preamplified coherent detection is not used in applications as commonly as optically preamplified direct detection. We investigate the performance of coherent detection employing a fiber amplifier and time-domain-filter. The fiber amplifier is used as the optical preamplifier of the coherent detection system. To reduce the noise induced by the preamplifier to a maximum extent, we investigate the noise properties for both a single pass amplifier and a double pass amplifier. The relative intensity noise and linewidth broadening caused by ASE have been experimentally characterized. The results show that the double pass amplifier has

  7. Optical coherent detection Brillouin distributed optical fiber sensor based on orthogonal polarization diversity reception

    Institute of Scientific and Technical Information of China (English)

    Muping Song; Bin Zhao; Xianmin Zhang


    In Brillouin distributed optical fiber sensor, using optical coherent detection to detect Brillouin scattering optical signal is a good method, but there exists the polarization correlated detection problem. A novel detecting scheme is presented and demonstrated experimentally, which adopts orthogonal polarization diversity reception to resolve the polarization correlated detection problem. A laser is used as pump and reference light sources, a microwave electric-optical modulator (EOM) is adopted to produce frequency shift reference light, a polarization controller is used to control the polarization of the reference light which is changed into two orthogonal polarization for two adjacent acquisition periods. The Brillouin scattering light is coherently detected with the reference light, and the Brillouin scattering optical signal is taken out based on Brillouin frequency shift. After electronic processing, better Brillouin distributed sensing signal is obtained. A 25-km Brillouin distributed optical fiber sensor is achieved.

  8. Sensing of Tooth Microleakage Based on Dental Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Chia-Wei Sun


    Full Text Available This study describes microleakage sensing based on swept-source optical coherence tomography (SS-OCT. With a handheld scanning probe, the SS-OCT system can provide portable real-time imaging for clinical diagnosis. Radiography is the traditional clinical imaging instrument used for dentistry; however, it does not provide good contrast images between filling material and the enamel of treated teeth with microleakage. The results of this study show that microleakage can be detected with oral probing using SS-OCT in vivo. The calculated microleakage length was 401 μm and the width is 148 μm, which is consistent with the related histological biopsy measurements. The diagnosis of microleakage in teeth could be useful for prevention of secondary caries in the clinical treatment plans developed in the field of oral medicine.

  9. Passive endoscopic polarization sensitive optical coherence tomography with completely fiber based optical components (United States)

    Cahill, Lucas; Lee, Anthony M. D.; Pahlevaninezhad, Hamid; Ng, Samson; MacAulay, Calum E.; Poh, Catherine; Lane, Pierre


    Polarization Sensitive Optical Coherence Tomography (PSOCT) is a functional extension of Optical Coherence Tomography (OCT) that is sensitive to well-structured, birefringent tissue such as scars, smooth muscle and cartilage. In this work, we present a novel completely fiber based swept source PSOCT system using a fiber-optic rotary pullback catheter. This PSOCT implementation uses only passive optical components and requires no calibration while adding minimal additional cost to a standard structural OCT imaging system. Due to its complete fiber construction, the system can be made compact and robust, while the fiber-optic catheter allows access to most endoscopic imaging sites. The 1.5mm diameter endoscopic probe can capture 100 frames per second at pullback speeds up to 15 mm/s allowing rapid traversal of large imaging fields. We validate the PSOCT system with known birefringent tissues and demonstrate in vivo PSOCT imaging of human oral scar tissue.

  10. Miniature optical coherence tomography system based on silicon photonics (United States)

    Margallo-Balbás, Eduardo; Pandraud, Gregory; French, Patrick J.


    Optical Coherence Tomography (OCT) is a promising medical imaging technique. It has found applications in many fields of medicine and has a large potential for the optical biopsy of tumours. One of the technological challenges impairing faster adoption of OCT is the relative complexity of the optical instrumentation required, which translates into expensive and bulky setups. In this paper we report an implementation of Time Domain OCT (TD-OCT) based on a silicon photonic platform. The devices are fabricated using Silicon-On-Insulator (SOI) wafers, on which rib waveguides are defined. While most of the components needed are well-known in this technology, a fast delay line with sufficient scanning range is a specific requirement of TD-OCT. In the system reported, this was obtained making use of the thermo-optical effect of silicon. By modulating the thermal resistance of the waveguide to the substrate, it is possible to establish a trade-off between maximum working frequency and power dissipation. Within this trade-off, the systems obtained can be operated in the kHz range, and they achieve temperature shifts corresponding to scanning ranges of over 2mm. Though the current implementation still requires external sources and detectors to be coupled to the Planar Lightwave Circuit (PLC), future work will include three-dimensional integration of these components onto the substrate. With the potential to include the read-out and driving electronics on the same die, the reported approach can yield extremely compact and low-cost TD-OCT systems, enabling a wealth of new applications, including gastrointestinal pills with optical biopsy capabilities.

  11. Optical coherence tomography-based micro-particle image velocimetry. (United States)

    Mujat, Mircea; Ferguson, R Daniel; Iftimia, Nicusor; Hammer, Daniel X; Nedyalkov, Ivaylo; Wosnik, Martin; Legner, Hartmut


    We present a new application of optical coherence tomography (OCT), widely used in biomedical imaging, to flow analysis in near-wall hydrodynamics for marine research. This unique capability, called OCT micro-particle image velocimetry, provides a high-resolution view of microscopic flow phenomena and measurement of flow statistics within the first millimeter of a boundary layer. The technique is demonstrated in a small flow cuvette and in a water tunnel.

  12. Video-rate volumetric optical coherence tomography-based microangiography (United States)

    Baran, Utku; Wei, Wei; Xu, Jingjiang; Qi, Xiaoli; Davis, Wyatt O.; Wang, Ruikang K.


    Video-rate volumetric optical coherence tomography (vOCT) is relatively young in the field of OCT imaging but has great potential in biomedical applications. Due to the recent development of the MHz range swept laser sources, vOCT has started to gain attention in the community. Here, we report the first in vivo video-rate volumetric OCT-based microangiography (vOMAG) system by integrating an 18-kHz resonant microelectromechanical system (MEMS) mirror with a 1.6-MHz FDML swept source operating at ˜1.3 μm wavelength. Because the MEMS scanner can offer an effective B-frame rate of 36 kHz, we are able to engineer vOMAG with a video rate up to 25 Hz. This system was utilized for real-time volumetric in vivo visualization of cerebral microvasculature in mice. Moreover, we monitored the blood perfusion dynamics during stimulation within mouse ear in vivo. We also discussed this system's limitations. Prospective MEMS-enabled OCT probes with a real-time volumetric functional imaging capability can have a significant impact on endoscopic imaging and image-guided surgery applications.

  13. Fourier optics analysis of phase-mask-based path-length-multiplexed optical coherence tomography. (United States)

    Yin, Biwei; Dwelle, Jordan; Wang, Bingqing; Wang, Tianyi; Feldman, Marc D; Rylander, Henry G; Milner, Thomas E


    Optical coherence tomography (OCT) is an imaging technique that constructs a depth-resolved image by measuring the optical path-length difference between broadband light backscattered from a sample and a reference surface. For many OCT sample arm optical configurations, sample illumination and backscattered light detection share a common path. When a phase mask is placed in the sample path, features in the detected signal are observed, which suggests that an analysis of a generic common path OCT imaging system is warranted. In this study, we present a Fourier optics analysis using a Fresnel diffraction approximation of an OCT system with a path-length-multiplexing element (PME) inserted in the sample arm optics. The analysis may be generalized for most phase-mask-based OCT systems. A radial-angle-diverse PME is analyzed in detail, and the point spread function, coherent transfer function, sensitivity of backscattering angular diversity detection, and signal formation in terms of sample spatial frequency are simulated and discussed. The analysis reveals important imaging features and application limitations of OCT imaging systems with a phase mask in the sample path optics.

  14. Optical Coherence and Quantum Optics

    CERN Document Server

    Mandel, Leonard


    This book presents a systematic account of optical coherence theory within the framework of classical optics, as applied to such topics as radiation from sources of different states of coherence, foundations of radiometry, effects of source coherence on the spectra of radiated fields, coherence theory of laser modes, and scattering of partially coherent light by random media. The book starts with a full mathematical introduction to the subject area and each chapter concludes with a set of exercises. The authors are renowned scientists and have made substantial contributions to many of the topi

  15. DSP based coherent receiver for phase-modulated radio-over-fiber optical links

    DEFF Research Database (Denmark)

    Zibar, Darko; Tafur Monroy, Idelfonso; Peucheret, Christophe


    A novel DSP based coherent receiver for phase modulated radio-over-fiber optical links is reported. Using the proposed digital receiver, signal demodulation of 1.25 Gb/s ASK-modulated 10 GHz RF carrier is experimentally demonstrated.......A novel DSP based coherent receiver for phase modulated radio-over-fiber optical links is reported. Using the proposed digital receiver, signal demodulation of 1.25 Gb/s ASK-modulated 10 GHz RF carrier is experimentally demonstrated....

  16. QoS-aware precautionary performance monitoring for PCE-based coherent optical OFDM networks

    Institute of Scientific and Technical Information of China (English)

    Yueming Lu; Lianxing Hou


    A quality-of-service (QoS) aware scheme,called precautionary performance monitoring,is proposed to solve the optical impairments and congestion control in coherent optical orthogonal frequency division multiplexed (CO-OFDM) networks.The centralized path computation element (PCE) extensions based on the QoS level are applied to optical performance monitoring in this letter.

  17. Spectrally encoded common-path fiber-optic-based parallel optical coherence tomography. (United States)

    Lee, Kye-Sung; Hur, Hwan; Sung, Ha-Young; Kim, I Jong; Kim, Geon-Hee


    We demonstrate a fiber-optic-based parallel optical coherence tomography (OCT) using spectrally encoded extended illumination with a common-path handheld probe, where the flexibility and robustness of the system are significantly improved, which is critical in the clinical environment. To the best of our knowledge, we present the first parallel OCT based on fiber optics including a fiber coupler with a sensitivity of 94 dB, which is comparable to that of point-scanning OCT. We also investigated the effect of the phase stability of the fiber-based interferometry on the parallel OCT system by comparing the common-path OCT with two-arm OCT. Using the homemade common-path handheld probe based on a Mirau interferometer, the phase stability was 32 times better than that of the two-arm OCT. The axial resolution of the common-path OCT was measured as 5.1±0.3  μm. To demonstrate the in vivo imaging performance of the fiber-optic-based parallel OCT, human skin was imaged.

  18. GPU-based computational adaptive optics for volumetric optical coherence microscopy (United States)

    Tang, Han; Mulligan, Jeffrey A.; Untracht, Gavrielle R.; Zhang, Xihao; Adie, Steven G.


    Optical coherence tomography (OCT) is a non-invasive imaging technique that measures reflectance from within biological tissues. Current higher-NA optical coherence microscopy (OCM) technologies with near cellular resolution have limitations on volumetric imaging capabilities due to the trade-offs between resolution vs. depth-of-field and sensitivity to aberrations. Such trade-offs can be addressed using computational adaptive optics (CAO), which corrects aberration computationally for all depths based on the complex optical field measured by OCT. However, due to the large size of datasets plus the computational complexity of CAO and OCT algorithms, it is a challenge to achieve high-resolution 3D-OCM reconstructions at speeds suitable for clinical and research OCM imaging. In recent years, real-time OCT reconstruction incorporating both dispersion and defocus correction has been achieved through parallel computing on graphics processing units (GPUs). We add to these methods by implementing depth-dependent aberration correction for volumetric OCM using plane-by-plane phase deconvolution. Following both defocus and aberration correction, our reconstruction algorithm achieved depth-independent transverse resolution of 2.8 um, equal to the diffraction-limited focal plane resolution. We have translated the CAO algorithm to a CUDA code implementation and tested the speed of the software in real-time using two GPUs - NVIDIA Quadro K600 and Geforce TITAN Z. For a data volume containing 4096×256×256 voxels, our system's processing speed can keep up with the 60 kHz acquisition rate of the line-scan camera, and takes 1.09 seconds to simultaneously update the CAO correction for 3 en face planes at user-selectable depths.

  19. Novel coherent optical OFDM-based transponder for optical slot switched networks

    DEFF Research Database (Denmark)

    Mestre, Miquel A.; Estaran, Jose M.; Jenneve, Philippe


    We report a novel coherent optical OFDM transponder approach capable of recovering microsecond-scale data-burst while adapting to tight filtering constraints present in optical slot switched intradatacenter networks. Filtering effects in such large node-count environments are reviewed. The CO...

  20. Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Fercher, A.F.; Andersen, Peter E.


    Optical coherence tomography (OCT) is a technique that is used to peer inside a body noninvasively. Tissue structure defined by tissue absorption and scattering coefficients, and the speed of blood flow, are derived from the characteristics of light remitted by the body. Singly backscattered light...... used in the medical field, in particular, in ophthalmology. Owing to the high transmissivity of ocular media, the depth penetration is considerable. Corresponding applications in dermatology are somewhat hindered by the strong scattering of epidermic tissue (μs ≈ 102 mm−1). As OCT provides images...... for intraoperative monitoring, and in microsurgical intervention. Optical biopsy based on OCT also provides diagnostic information by differentiating the architectural morphology of urological tissue, gastrointestinal tissue, and respiratory tissue....

  1. Performance analysis of fiber-based free-space optical communications with coherent detection spatial diversity. (United States)

    Li, Kangning; Ma, Jing; Tan, Liying; Yu, Siyuan; Zhai, Chao


    The performances of fiber-based free-space optical (FSO) communications over gamma-gamma distributed turbulence are studied for multiple aperture receiver systems. The equal gain combining (EGC) technique is considered as a practical scheme to mitigate the atmospheric turbulence. Bit error rate (BER) performances for binary-phase-shift-keying-modulated coherent detection fiber-based free-space optical communications are derived and analyzed for EGC diversity receptions through an approximation method. To show the net diversity gain of a multiple aperture receiver system, BER performances of EGC are compared with a single monolithic aperture receiver system with the same total aperture area (same average total incident optical power on the aperture surface) for fiber-based free-space optical communications. The analytical results are verified by Monte Carlo simulations. System performances are also compared for EGC diversity coherent FSO communications with or without considering fiber-coupling efficiencies.

  2. Three dimensional image reconstruction based on a wide-field optical coherence tomography system (United States)

    Feng, Yinqi; Feng, Shengtong; Zhang, Min; Hao, Junjun


    Wide-field optical coherence tomography has a promising application for its high scanning rate and resolution. The principle of a wide-field optical coherence tomography system is described, and 2D images of glass slides are reconstructed using eight-stepped phase-shifting method in the system. Using VC6.0 and OpenGL programming, 3D images are reconstructed based on the Marching Cube algorithm with 2D image sequences. The experimental results show that the depth detection and three-dimensional tomography for translucent materials could be implemented efficiently in the WFOCT system.

  3. Wavefront sensing based on phase contrast theory and coherent optical processing (United States)

    Lei, Huang; Qi, Bian; Chenlu, Zhou; Tenghao, Li; Mali, Gong


    A novel wavefront sensing method based on phase contrast theory and coherent optical processing is proposed. The wavefront gradient field in the object plane is modulated into intensity distribution in a gang of patterns, making high-density detection available. By applying the method, we have also designed a wavefront sensor. It consists of a classical coherent optical processing system, a CCD detector array, two pieces of orthogonal composite sinusoidal gratings, and a mechanical structure that can perform real-time linear positioning. The simulation results prove and demonstrate the validity of the method and the sensor in high-precision measurement of the wavefront gradient field.

  4. Retrospective image-based gating of intracoronary optical coherence tomography: Implications for quantitative analysis

    NARCIS (Netherlands)

    K. Sihan (Kenji); C.P. Botha (Charl); F.H. Post (Frits); S. de Winter (Sebastiaan); N. Gonzalo (Nieves); E.S. Regar (Eveline); P.W.J.C. Serruys (Patrick); R. Hamers (Ronald); N. Bruining (Nico)


    textabstractAims: Images acquired of coronary vessels during a pullback of time-domain optical coherence tomography (OCT) are influenced by the dynamics of the heart. This study explores the feasibility of applying an in-house developed retrospective image-based gating method for OCT and the influen

  5. Swept source optical coherence tomography based on non-uniform discrete fourier transform

    Institute of Scientific and Technical Information of China (English)

    Tong Wu; Zhihua Ding; Kai Wang; Chuan Wang


    A high-speed high-sensitivity swept source optical coherence tomography (SSOCT) system using a high speed swept laser source is developed.Non-uniform discrete fourier transform (NDFT) method is introduced in the SSOCT system for data processing.Frequency calibration method based on a Mach-Zender interferometer (MZI) and conventional data interpolation method is also adopted in the system for comparison.Optical coherence tomography (OCT) images from SSOCT based on the NDFT method,the MZI method,and the interpolation method are illustrated.The axial resolution of the SSOCT based on the NDFT method is comparable to that of the SSOCT system using MZI calibration method and conventional data interpolation method.The SSOCT system based on the NDFT method can achieve higher signal intensity than that of the system based on the MZI calibration method and conventional data interpolation method because of the better utilization of the power of source.

  6. Dental Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Kun-Feng Lin


    Full Text Available This review paper describes the applications of dental optical coherence tomography (OCT in oral tissue images, caries, periodontal disease and oral cancer. The background of OCT, including basic theory, system setup, light sources, spatial resolution and system limitations, is provided. The comparisons between OCT and other clinical oral diagnostic methods are also discussed.

  7. Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Andersen, Peter E.


    Optical coherence tomography (OCT) is a noninvasive imaging technique that provides real-time two- and three-dimensional images of scattering samples with micrometer resolution. Mapping the local reflectivity, OCT visualizes the morphology of the sample, in real time or at video rate. In addition...

  8. Computational Principle and Performance Evaluation of Coherent Ising Machine Based on Degenerate Optical Parametric Oscillator Network

    Directory of Open Access Journals (Sweden)

    Yoshitaka Haribara


    Full Text Available We present the operational principle of a coherent Ising machine (CIM based on a degenerate optical parametric oscillator (DOPO network. A quantum theory of CIM is formulated, and the computational ability of CIM is evaluated by numerical simulation based on c-number stochastic differential equations. We also discuss the advanced CIM with quantum measurement-feedback control and various problems which can be solved by CIM.

  9. A Coherent Ising Machine Based On Degenerate Optical Parametric Oscillators (United States)

    Wang, Zhe; Marandi, Alireza; Wen, Kai; Byer, Robert L.; Yamamoto, Yoshihisa


    A degenerate optical parametric oscillator network is proposed to solve the NP-hard problem of finding a ground state of the Ising model. The underlying operating mechanism originates from the bistable output phase of each oscillator and the inherent preference of the network in selecting oscillation modes with the minimum photon decay rate. Computational experiments are performed on all instances reducible to the NP-hard MAX-CUT problems on cubic graphs of order up to 20. The numerical results reasonably suggest the effectiveness of the proposed network. This project is supported by the FIRST program of Japanese Government. Zhe Wang is also grateful for the support from Stanford Graduate Fellowship.

  10. Optical coherence tomography based microangiography: A tool good for dermatology applications (Conference Presentation) (United States)

    Wang, Ruikang K.; Baran, Utku; Choi, Woo J.


    Optical coherence tomography (OCT) based microangiography (OMAG) is a new imaging technique enabling the visualization of blood flow within microcirculatory tissue beds in vivo with high resolution. In this talk, the concept and advantages of OMAG will be discussed and its potential clinical applications in the dermatology will be shown, demonstrating its usefulness in the clinical monitoring and therapeutic treatment of various skin pathologies, e.g. acne, port wine stain and wound healing.

  11. In-vivo retinal imaging by optical coherence tomography using an RSOD-based phase modulator

    Institute of Scientific and Technical Information of China (English)

    Ling WANG; Zhi-hua DING; Guo-hua SHI; Yu-dong ZHANG


    Fourier-domain rapid scanning optical delay line (RSOD) was introduced for phase modulation and depth scanning in a time-domain optical coherence tomography (TD-OCT) system. Investigation of parameter optimization of RSOD was conducted.Experiments for RSOD characterization at different parameters of the groove pitch, focal length, galvomirror size, etc. were performed. By implementing the optimized RSOD in our established TD-OCT system with a broadband light source centered at 840 nm with 50 nm bandwidth, in vivo retina imaging of a rabbit was presented, demonstrating the feasibility of high-quality TD-OCT imaging using an RSOD-based phase modulator.

  12. Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Pier Alberto Testoni


    Full Text Available Optical coherence tomography (OCT is an optical imaging modality that performs high-resolution, cross-sectional, subsurface tomographic imaging of the microstructure of tissues. The physical principle of OCT is similar to that of B-mode ultrasound imaging, except that it uses infrared light waves rather than acoustic waves. The in vivo resolution is 10–25 times better (about 10 µm than with high-frequency ultrasound imaging, but the depth of penetration is limited to 1–3 mm, depending on tissue structure, depth of focus of the probe used, and pressure applied to the tissue surface. In the last decade, OCT technology has evolved from an experimental laboratory tool to a new diagnostic imaging modality with a wide spectrum of clinical applications in medical practice, including the gastrointestinal tract and pancreatico-biliary ductal system. OCT imaging from the gastrointestinal tract can be done in humans by using narrow-diameter, catheter-based probes that can be inserted through the accessory channel of either a conventional front-view endoscope, for investigating the epithelial structure of the gastrointestinal tract, or a side-view endoscope, inside a standard transparent ERCP (endoscopic retrograde cholangiopancreatography catheter, for investigating the pancreatico-biliary ductal system. The esophagus and esophagogastric junction have been the most widely investigated organs so far; more recently, duodenum, colon, and the pancreatico-biliary ductal system have also been extensively investigated. OCT imaging of the gastrointestinal wall structure is characterized by a multiple-layer architecture that permits an accurate evaluation of the mucosa, lamina propria, muscularis mucosae, and part of the submucosa. The technique may therefore be used to identify preneoplastic conditions of the gastrointestinal tract, such as Barrett's epithelium and dysplasia, and evaluate the depth of penetration of early-stage neoplastic lesions. OCT imaging

  13. Spectral phase-based automatic calibration scheme for swept source-based optical coherence tomography systems (United States)

    Ratheesh, K. M.; Seah, L. K.; Murukeshan, V. M.


    The automatic calibration in Fourier-domain optical coherence tomography (FD-OCT) systems allows for high resolution imaging with precise depth ranging functionality in many complex imaging scenarios, such as microsurgery. However, the accuracy and speed of the existing automatic schemes are limited due to the functional approximations and iterative operations used in their procedures. In this paper, we present a new real-time automatic calibration scheme for swept source-based optical coherence tomography (SS-OCT) systems. The proposed automatic calibration can be performed during scanning operation and does not require an auxiliary interferometer for calibration signal generation and an additional channel for its acquisition. The proposed method makes use of the spectral component corresponding to the sample surface reflection as the calibration signal. The spectral phase function representing the non-linear sweeping characteristic of the frequency-swept laser source is determined from the calibration signal. The phase linearization with improved accuracy is achieved by normalization and rescaling of the obtained phase function. The fractional-time indices corresponding to the equidistantly spaced phase intervals are estimated directly from the resampling function and are used to resample the OCT signals. The proposed approach allows for precise calibration irrespective of the path length variation induced by the non-planar topography of the sample or galvo scanning. The conceived idea was illustrated using an in-house-developed SS-OCT system by considering the specular reflection from a mirror and other test samples. It was shown that the proposed method provides high-performance calibration in terms of axial resolution and sensitivity without increasing computational and hardware complexity.

  14. Cadaveric in-situ testing of optical coherence tomography system-based skull base surgery guidance (United States)

    Sun, Cuiru; Khan, Osaama H.; Siegler, Peter; Jivraj, Jamil; Wong, Ronnie; Yang, Victor X. D.


    Optical Coherence Tomography (OCT) has extensive potential for producing clinical impact in the field of neurological diseases. A neurosurgical OCT hand-held forward viewing probe in Bayonet shape has been developed. In this study, we test the feasibility of integrating this imaging probe with modern navigation technology for guidance and monitoring of skull base surgery. Cadaver heads were used to simulate relevant surgical approaches for treatment of sellar, parasellar and skull base pathology. A high-resolution 3D CT scan was performed on the cadaver head to provide baseline data for navigation. The cadaver head was mounted on existing 3- or 4-point fixation systems. Tracking markers were attached to the OCT probe and the surgeon-probe-OCT interface was calibrated. 2D OCT images were shown in real time together with the optical tracking images to the surgeon during surgery. The intraoperative video and multimodality imaging data set, consisting of real time OCT images, OCT probe location registered to neurosurgical navigation were assessed. The integration of intraoperative OCT imaging with navigation technology provides the surgeon with updated image information, which is important to deal with tissue shifts and deformations during surgery. Preliminary results demonstrate that the clinical neurosurgical navigation system can provide the hand held OCT probe gross anatomical localization. The near-histological imaging resolution of intraoperative OCT can improve the identification of microstructural/morphology differences. The OCT imaging data, combined with the neurosurgical navigation tracking has the potential to improve image interpretation, precision and accuracy of the therapeutic procedure.

  15. Optical Coherence Tomography (United States)

    Huang, David

    Optical coherence tomography (OCT) is a new method for noninvasive cross-sectional imaging in biological systems. In OCT, the longitudinal locations of tissue structures are determined by measuring the time-of-flight delays of light backscattered from these structures. The optical delays are measured by low coherence interferometry. Information on lateral position is provided by transverse scanning of the probe beam. The two dimensional map of optical scattering from internal tissue microstructures is then represented in a false-color or grayscale image. OCT is the optical analog of ultrasonic pulse-echo imaging, but with greatly improved spatial resolutions (a few microns). This thesis describes the development of this new high resolution tomographic imaging technology and the demonstration of its use in a variety of tissues under both in vitro and in vivo conditions. In vitro OCT ranging and imaging studies were performed using human ocular and arterial tissues, two clinically relevant examples of transparent and turbid media, respectively. In the anterior eye, precise measurements of cornea and anterior chamber dimensions were made. In the arterial specimens, the differentiation between fatty -calcified and fibromuscular tissues was demonstrated. In vivo OCT imaging in the retina and optic nerve head in human subjects was also performed. The delineation of retinal layers, which has not been possible with other noninvasive imaging techniques, is demonstrated in these OCT images. OCT has high spatial resolution but limited penetration into turbid tissue. It has potential for diagnostic applications where high resolution is needed and optical access is available, such as in the eye, skin, surgically exposed tissues, and surfaces that can be reached by various catheters and endoscopic probes. In particular, the measurement of fine retinal structures promises improvements in the diagnosis and management of glaucoma, macular edema and other vitreo-retinal diseases

  16. Phase noise estimation and mitigation for DCT-based coherent optical OFDM systems. (United States)

    Yang, Chuanchuan; Yang, Feng; Wang, Ziyu


    In this paper, as an attractive alternative to the conventional discrete Fourier transform (DFT) based orthogonal frequency division multiplexing (OFDM), discrete cosine transform (DCT) based OFDM which has certain advantages over its counterpart is studied for optical fiber communications. As is known, laser phase noise is a major impairment to the performance of coherent optical OFDM (CO-OFDM) systems. However, to our knowledge, detailed analysis of phase noise and the corresponding mitigation methods for DCT-based CO-OFDM systems have not been reported yet. To address these issues, we analyze the laser phase noise in the DCT-based CO-OFDM systems, and propose phase noise estimation and mitigation schemes. Numerical results show that the proposal is very effective in suppressing phase noise and could significantly improve the performance of DCT-based CO-OFDM systems.

  17. Diffraction coherence in optics

    CERN Document Server

    Françon, M; Green, L L


    Diffraction: Coherence in Optics presents a detailed account of the course on Fraunhofer diffraction phenomena, studied at the Faculty of Science in Paris. The publication first elaborates on Huygens' principle and diffraction phenomena for a monochromatic point source and diffraction by an aperture of simple form. Discussions focus on diffraction at infinity and at a finite distance, simplified expressions for the field, calculation of the path difference, diffraction by a rectangular aperture, narrow slit, and circular aperture, and distribution of luminous flux in the airy spot. The book th

  18. Coherent optical methods for metallography

    Energy Technology Data Exchange (ETDEWEB)

    Pechersky, M.J.


    Numerous methods based on coherent optical techniques have been developed over the past two decades for nondestructive evaluation, vibration analysis and experimental mechanics. These methods have a great deal of potential for the enhancement of metallographic evaluations and for materials characterization in general. One such technique described in this paper is the determination of the material damping factors in metals. Damping loss factors as low as 10-5 were measured on bronze and aluminum specimens using a technique based on laser vibrometry. Differences between cast and wrought bronze were easily distinguishable as well as the difference between the bronze and aluminum. Other coherent optical techniques may be used to evaluate residual stresses and to locate and identify microcracking, subsurface voids and other imperfections. These techniques and others can serve as a bridge between microstructural investigations and the macroscopic behavior of materials.

  19. Coherent optical methods for metallography

    Energy Technology Data Exchange (ETDEWEB)

    Pechersky, M.J.


    Numerous methods based on coherent optical techniques have been developed over the past two decades for nondestructive evaluation, vibration analysis and experimental mechanics. These methods have a great deal of potential for the enhancement of metallographic evaluations and for materials characterization in general. One such technique described in this paper is the determination of the material damping factors in metals. Damping loss factors as low as 10-5 were measured on bronze and aluminum specimens using a technique based on laser vibrometry. Differences between cast and wrought bronze were easily distinguishable as well as the difference between the bronze and aluminum. Other coherent optical techniques may be used to evaluate residual stresses and to locate and identify microcracking, subsurface voids and other imperfections. These techniques and others can serve as a bridge between microstructural investigations and the macroscopic behavior of materials.

  20. Parameters measurement of rigid gas permeable contact lens based on optical coherence tomography (United States)

    Zhu, Dexi; Shen, Meixiao; Li, Yiyu


    Spectral domain optical coherence tomography (OCT) was developed in order to measure the geometric parameters of rigid gas permeable (RGP) contact lens. With custom designed OCT system, an ultra-high axial resolution of 3.3 μm in lens was achieved. The OCT image was corrected to eliminate the optical distortion and actual surfaces of lens were shown in contour map. Central thickness, lens diameter, base curve and front surface curvature at optical zone were calculated from the contour map. The results match well with the real values measured by conventional instruments. Our research indicates that OCT can be used to test the RGP lens in a simple and exact way.

  1. Fiber-Based Polarization Diversity Detection for Polarization-Sensitive Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Hamid Pahlevaninezhad


    Full Text Available We present a new fiber-based polarization diversity detection (PDD scheme for polarization sensitive optical coherence tomography (PSOCT. This implementation uses a new custom miniaturized polarization-maintaining 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 two orthogonal OCT polarization channels prior to interference while the PM fiber outputs ensure defined orthogonal axes after interference. Advantages of this detection scheme over those with bulk optics PDD include lower cost, easier miniaturization, and more relaxed alignment and handling issues. We incorporate this PDD scheme into a galvanometer-scanned OCT system to demonstrate system calibration and PSOCT imaging of an achromatic quarter-wave plate, fingernail in vivo, and chicken breast, salmon, cow leg, and basa fish muscle samples ex vivo.

  2. Speckle-metric-optimization-based adaptive optics for laser beam projection and coherent beam combining. (United States)

    Vorontsov, Mikhail; Weyrauch, Thomas; Lachinova, Svetlana; Gatz, Micah; Carhart, Gary


    Maximization of a projected laser beam's power density at a remotely located extended object (speckle target) can be achieved by using an adaptive optics (AO) technique based on sensing and optimization of the target-return speckle field's statistical characteristics, referred to here as speckle metrics (SM). SM AO was demonstrated in a target-in-the-loop coherent beam combining experiment using a bistatic laser beam projection system composed of a coherent fiber-array transmitter and a power-in-the-bucket receiver. SM sensing utilized a 50 MHz rate dithering of the projected beam that provided a stair-mode approximation of the outgoing combined beam's wavefront tip and tilt with subaperture piston phases. Fiber-integrated phase shifters were used for both the dithering and SM optimization with stochastic parallel gradient descent control.

  3. Resolving directional ambiguity in dynamic light scattering-based transverse motion velocimetry in optical coherence tomography (United States)

    Huang, Brendan K.; Choma, Michael A.


    Dynamic Light Scattering-based Optical Coherence Tomography approaches have been successfully implemented to measure total transverse (xy) flow speed, but are unable to resolve directionality. We propose a method to extract directional velocity in the transverse plane by introducing a variable scan bias to our system. Our velocity estimation, which yields the directional velocity component along the scan axis, is also independent of any point spread function calibration. By combining our approach with Doppler velocimetry, we show three-component velocimetry that is appropriately dependent on latitudinal and longitudinal angle. PMID:24487855

  4. Dynamic measurement of local displacements within curing resin-based dental composite using optical coherence elastography (United States)

    Tomlins, Peter H.; Rahman, Mohammed Wahidur; Donnan, Robert S.


    This study aimed to determine the feasibility of using optical coherence elastography to measure internal displacements during the curing phase of a light-activated, resin-based composite material. Displacement vectors were spatially mapped over time within a commercial dental composite. Measurements revealed that the orientation of cure-induced displacement vectors varied spatially in a complex manner; however, each vector showed a systematic evolution with time. Precision of individual displacements was estimated to be ˜1 to 2 μm, enabling submicrometer time-varying displacements to be detected.

  5. Colorectal neoplasm characterization based on swept-source optical coherence tomography (United States)

    Lu, Chih-Wei; Chiu, Han-Mo; Sun, Chia-Wei


    Most of the colorectal cancer has grown from the adenomatous polyp. Adenomatous lesions have a well-documented relationship to colorectal cancer in previous studies. Thus, to detect the morphological changes between polyp and tumor can allow early diagnosis of colorectal cancer and simultaneous removal of lesions. In this paper, the various adenoma/carcinoma in-vitro samples are monitored by our swept-source optical coherence tomography (SS-OCT) system. The significant results indicate a great potential for early detection of colorectal adenomas based on the SS-OCT imaging.

  6. A linear coherent integrated receiver based on a broadband optical phase-locked loop (United States)

    Ramaswamy, Anand

    Optical Phase-Locked Loops (OPLL) have diverse applications in future communication systems. They can be used in high sensitivity homodyne phase-shift keying receivers for phase noise reduction, provided sufficient loop bandwidth is maintained. Alternative phase-locked loop applications include coherent synchronization of laser arrays and frequency synthesis by offset locking. In this work, a broadband OPLL based coherent receiver is used for linear phase demodulation. Phase modulated (PM) analog optical links have the potential to outperform conventional direct detection links. However, their progress has been stymied by the lack of a linear phase demodulator. We describe how feedback can be used to suppress non-linearities arising from the phase demodulation process. The receiver concept is demonstrated at low frequencies and is found to improve the Spurious Free Dynamic Range (SFDR) of an experimental analog link by over 20dB. In order to extend the operation of the receiver to microwave frequencies, latencies arising from physical delays in the feedback path need to be dramatically reduced. To facilitate this, monolithic and hybrid versions of the receiver based on compact integration of InP photonic integrated circuits (PIC) with InP and SiGe electronic integrated circuits (EIC) have been developed at UCSB. In this work, we develop novel measurement techniques to characterize the linearity of the individual components of the PIC, namely, the semiconductor photodiodes and optical phase modulators. We then demonstrate the operation of the receiver in a high power analog link. The OPLL based receiver has a bandwidth of 1.5GHz. The link gain and shot-noise limited SFDR at 300MHz are -2dB and 125dB-Hz2/3, respectively. Further, optical sampling downconversion is demonstrated as a viable technique to increase the operating frequency of the receiver beyond the baseband range.

  7. Coherence evolution of partially coherent beams carrying optical vortices propagating in non-Kolmogorov turbulence. (United States)

    Qin, Zhiyuan; Tao, Rumao; Zhou, Pu; Xu, Xiaojun; Liu, Zejin


    Based on partially coherent Bessel-Gaussian beams (BGBs), the coherence evolution of the partially coherent beams carrying optical vortices in non-Kolmogorov turbulence is investigated in detail. The analytical formulas for the spatial coherence length of partially coherent BGBs with optical vortices in non-Kolmogorov turbulence have been derived by using the combination of a coherence superposition approximation of decentered Gaussian beams and the extended Huygens-Fresnel principle. The influences of beam and turbulence parameters on spatial coherence are investigated by numerical examples. Numerical results reveal that the coherence of the partially coherent laser beam with vortices is independent of the optical vortices, and the spatial correlation length of the beams does not decrease monotonically during propagation in non-Kolmogorov turbulence. Within a certain propagation distance, the coherence of the partially coherent beam will improve, and the improvement of the coherence of the partially coherent beams is closely related to the beam and turbulence parameters.

  8. Numerical analysis of astigmatism correction in gradient refractive index lens based optical coherence tomography catheters

    NARCIS (Netherlands)

    T. Wang (Teng); A.F.W. van der Steen (Ton); G. van Soest (Gijs)


    textabstractEndoscopic optical coherence tomography (OCT) catheters comprise a transparent tube to separate the imaging instrument from tissues. This tube acts as a cylindrical lens, introducing astigmatism into the beam. In this report, we quantified this negative effect using optical simulations o

  9. Dental optical coherence domain reflectometry explorer

    Energy Technology Data Exchange (ETDEWEB)

    Everett, Matthew J. (Livermore, CA); Colston, Jr., Billy W. (Livermore, CA); Sathyam, Ujwal S. (Livermore, CA); Da Silva, Luiz B. (Pleasanton, CA)


    A hand-held, fiber optic based dental device with optical coherence domain reflectometry (OCDR) sensing capabilities provides a profile of optical scattering as a function of depth in the tissue at the point where the tip of the dental explorer touches the tissue. This system provides information on the internal structure of the dental tissue, which is then used to detect caries and periodontal disease. A series of profiles of optical scattering or tissue microstructure are generated by moving the explorer across the tooth or other tissue. The profiles are combined to form a cross-sectional, or optical coherence tomography (OCT), image.

  10. Coherent optical propagation and ultrahigh resolution mass sensor based on photonic molecules optomechanics (United States)

    Chen, Hua-Jun; Chen, Chang-Zhao; Li, Yang; Fang, Xian-Wen; Tang, Xu-Dong


    We theoretically demonstrate the coherent optical propagation properties based on a photonic molecules optomechanics. With choosing a suitable detuning of the pump field from optomechanical cavity resonance, both the slow- and fast-light effect of the probe field appear in the system. The coupling strength of the two cavities play a key role, which affords a quantum channel and influences the width of the transparency window. Based on the photonic molecules optomechanical system, a high resolution mass sensor is also proposed. The mass of external nanoparticles deposited onto the cavity can be measured straightforward via tracking the mechanical resonance frequency shifts due to mass changes in the probe transmission spectrum. Compared with the single-cavity optomechanics mass sensors, the mass resolution is improved significantly due to the cavity-cavity coupling. The photonic molecules optomechanics provide a new platform for on-chip applications in quantum information processing and ultrahigh resolution sensor devices.

  11. Spiking cortical model-based nonlocal means method for speckle reduction in optical coherence tomography images. (United States)

    Zhang, Xuming; Li, Liu; Zhu, Fei; Hou, Wenguang; Chen, Xinjian


    Optical coherence tomography (OCT) images are usually degraded by significant speckle noise, which will strongly hamper their quantitative analysis. However, speckle noise reduction in OCT images is particularly challenging because of the difficulty in differentiating between noise and the information components of the speckle pattern. To address this problem, the spiking cortical model (SCM)-based nonlocal means method is presented. The proposed method explores self-similarities of OCT images based on rotation-invariant features of image patches extracted by SCM and then restores the speckled images by averaging the similar patches. This method can provide sufficient speckle reduction while preserving image details very well due to its effectiveness in finding reliable similar patches under high speckle noise contamination. When applied to the retinal OCT image, this method provides signal-to-noise ratio improvements of >16  dB with a small 5.4% loss of similarity.

  12. Spiking cortical model-based nonlocal means method for speckle reduction in optical coherence tomography images (United States)

    Zhang, Xuming; Li, Liu; Zhu, Fei; Hou, Wenguang; Chen, Xinjian


    Optical coherence tomography (OCT) images are usually degraded by significant speckle noise, which will strongly hamper their quantitative analysis. However, speckle noise reduction in OCT images is particularly challenging because of the difficulty in differentiating between noise and the information components of the speckle pattern. To address this problem, the spiking cortical model (SCM)-based nonlocal means method is presented. The proposed method explores self-similarities of OCT images based on rotation-invariant features of image patches extracted by SCM and then restores the speckled images by averaging the similar patches. This method can provide sufficient speckle reduction while preserving image details very well due to its effectiveness in finding reliable similar patches under high speckle noise contamination. When applied to the retinal OCT image, this method provides signal-to-noise ratio improvements of >16 dB with a small 5.4% loss of similarity.

  13. Fiber-optical sensor with miniaturized probe head and nanometer accuracy based on spatially modulated low-coherence interferogram analysis. (United States)

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


    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.

  14. Coherent signal processing in optical coherence tomography (United States)

    Kulkarni, Manish Dinkarrao


    Optical coherence tomography (OCT) is a novel method for non-invasive sub-surface imaging of biological tissue micro-structures. OCT achieves high spatial resolution ( ~ 15 m m in three dimensions) using a fiber-optically integrated system which is suitable for application in minimally invasive diagnostics, including endoscopy. OCT uses an optical heterodyne detection technique based on white light interferometry. Therefore extremely faint reflections ( ~ 10 fW) are routinely detected with high spatial localization. The goal of this thesis is twofold. The first is to present a theoretical model for describing image formation in OCT, and attempt to enhance the current level of understanding of this new modality. The second objective is to present signal processing methods for improving OCT image quality. We present deconvolution algorithms to obtain improved longitudinal resolution in OCT. This technique may be implemented without increasing system complexity as compared to current clinical OCT systems. Since the spectrum of the light backscattered from bio-scatterers is closely associated with ultrastructural variations in tissue, we propose a new technique for measuring spectra as a function of depth. This advance may assist OCT in differentiating various tissue types and detecting abnormalities within a tissue. In addition to depth resolved spectroscopy, Doppler processing of OCT signals can also improve OCT image contrast. We present a new technique, termed color Doppler OCT (CDOCT). It is an innovative extension of OCT for performing spatially localized optical Doppler velocimetry. Micron-resolution imaging of blood flow in sub-surface vessels in living tissue using CDOCT is demonstrated. The fundamental issues regarding the trade- off between the velocity estimation precision and image acquisition rate are presented. We also present novel algorithms for high accuracy velocity estimation. In many blood vessels velocities tend to be on the order of a few cm

  15. Full-field optical coherence tomography image restoration based on Hilbert transformation (United States)

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


    We propose the envelope detection method that is based on Hilbert transform for image restoration in full-filed optical coherence tomography (FF-OCT). The FF-OCT system presenting a high-axial resolution of 0.9 μm was implemented with a Kohler illuminator based on Linnik interferometer configuration. A 250 W customized quartz tungsten halogen lamp was used as a broadband light source and a CCD camera was used as a 2-dimentional detector array. The proposed image restoration method for FF-OCT requires only single phase-shifting. By using both the original and the phase-shifted images, we could remove the offset and the background signals from the interference fringe images. The desired coherent envelope image was obtained by applying Hilbert transform. With the proposed image restoration method, we demonstrate en-face imaging performance of the implemented FF-OCT system by presenting a tilted mirror surface, an integrated circuit chip, and a piece of onion epithelium.

  16. Optical Coherence Tomography: Advanced Modeling

    DEFF Research Database (Denmark)

    Andersen, Peter E.; Thrane, Lars; Yura, Harold T.;


    Analytical and numerical models for describing and understanding the light propagation in samples imaged by optical coherence tomography (OCT) systems are presented. An analytical model for calculating the OCT signal based on the extended Huygens-Fresnel principle valid both for the single......- and multiple-scattering regimes is derived. An advanced Monte Carlo model for calculating the OCT signal is also derived, and the validity of this model is shown through a mathematical proof based on the extended Huygens-Fresnel principle. From the analytical model, an algorithm for enhancing OCT images...... is developed, the so-called true-reflection algorithm in which the OCT signal may be corrected for the attenuation caused by scattering. The algorithm is verified experimentally and by using the Monte Carlo model as a numerical tissue phantom. Applications of extraction of optical properties from tissue...

  17. Endoscopic swept-source optical coherence tomography based on a two-axis microelectromechanical system mirror (United States)

    Wang, Donglin; Fu, Linlai; Wang, Xin; Gong, Zhongjian; Samuelson, Sean; Duan, Can; Jia, Hongzhi; Ma, Jun Shan; Xie, Huikai


    A microelectromechanical system (MEMS) mirror based endoscopic swept-source optical coherence tomography (SS-OCT) system that can perform three-dimensional (3-D) imaging at high speed is reported. The key component enabling 3-D endoscopic imaging is a two-axis MEMS scanning mirror which has a 0.8×0.8 mm2 mirror plate and a 1.6×1.4 mm2 device footprint. The diameter of the endoscopic probe is only 3.5 mm. The imaging rate of the SS-OCT system is 50 frames/s. OCT images of both human suspicious oral leukoplakia tissue and normal buccal mucosa were taken in vivo and compared. The OCT imaging result agrees well with the histopathological analysis.

  18. Loop-locked coherent population trapping magnetometer based on a fiber electro-optic modulator. (United States)

    Hu, Yong; Feng, Y Y; Xu, Chi; Xue, H B; Sun, Li


    We have set up a coherent population trapping (CPT)-based magnetometer prototype with the D1 line of ⁸⁷Rb atoms. The dichromatic light field is derived from a fiber electro-optic modulator (FEOM) connected to an external cavity laser diode. A CPT resonance signal with a 516 Hz linewidth is observed. By feeding back the derivative of the resonance curve to the FEOM with a proportional integral controller, of which the voltage output is directly converted to the measured magnetic field intensity, the resonance peak is locked to the environmental magnetic field. The measurement data we have achieved are well matched with the data measured by a commercial fluxgate magnetometer within 2 nT, and the sensitivity is better than 8 pT/√Hz in a parallel B field.

  19. Quantitative optical coherence elastography based on fiber-optic probe with integrated Fabry-Perot force sensor (United States)

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


    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.

  20. High-resolution handheld rigid endomicroscope based on full-field optical coherence tomography (United States)

    Benoit a la Guillaume, Emilie; Martins, Franck; Boccara, Claude; Harms, Fabrice


    Full-field optical coherence tomography (FF-OCT) is a powerful tool for nondestructive assessment of biological tissue, i.e., for the structural examination of tissue in depth at a cellular resolution. Mostly known as a microscopy device for ex vivo analysis, FF-OCT has also been adapted to endoscopy setups since it shows good potential for in situ cancer diagnosis and biopsy guidance. Nevertheless, all the attempts to perform endoscopic FF-OCT imaging did not go beyond lab setups. We describe here, to the best of our knowledge, the first handheld FF-OCT endoscope based on a tandem interferometry assembly using incoherent illumination. A common-path passive imaging interferometer at the tip of an optical probe makes it robust and insensitive to environmental perturbations, and a low finesse Fabry-Perot processing interferometer guarantees a compact system. A good resolution (2.7 μm transverse and 6 μm axial) is maintained through the long distance, small diameter relay optics of the probe, and a good signal-to-noise ratio is achieved in a limited 100 ms acquisition time. High-resolution images and a movie of a rat brain slice have been recorded by moving the contact endoscope over the surface of the sample, allowing for tissue microscopic exploration at 20 μm under the surface. These promising ex vivo results open new perspectives for in vivo imaging of biological tissue, in particular, in the field of cancer and surgical margin assessment.

  1. Application of improved homogeneity similarity-based denoising in optical coherence tomography retinal images. (United States)

    Chen, Qiang; de Sisternes, Luis; Leng, Theodore; Rubin, Daniel L


    Image denoising is a fundamental preprocessing step of image processing in many applications developed for optical coherence tomography (OCT) retinal imaging--a high-resolution modality for evaluating disease in the eye. To make a homogeneity similarity-based image denoising method more suitable for OCT image removal, we improve it by considering the noise and retinal characteristics of OCT images in two respects: (1) median filtering preprocessing is used to make the noise distribution of OCT images more suitable for patch-based methods; (2) a rectangle neighborhood and region restriction are adopted to accommodate the horizontal stretching of retinal structures when observed in OCT images. As a performance measurement of the proposed technique, we tested the method on real and synthetic noisy retinal OCT images and compared the results with other well-known spatial denoising methods, including bilateral filtering, five partial differential equation (PDE)-based methods, and three patch-based methods. Our results indicate that our proposed method seems suitable for retinal OCT imaging denoising, and that, in general, patch-based methods can achieve better visual denoising results than point-based methods in this type of imaging, because the image patch can better represent the structured information in the images than a single pixel. However, the time complexity of the patch-based methods is substantially higher than that of the others.

  2. Sensor-Based Technique for Manually Scanned Hand-Held Optical Coherence Tomography Imaging

    Directory of Open Access Journals (Sweden)

    Paritosh Pande


    Full Text Available Hand-held optical coherence tomography (OCT imaging probes offer flexibility to image sites that are otherwise challenging to access. While the majority of hand-held imaging probes utilize galvanometer- or MEMS-scanning mirrors to transversely scan the imaging beam, these probes are commonly limited to lateral fields-of-view (FOV of only a few millimeters. The use of a freehand manually scanned probe can significantly increase the lateral FOV. However, using the traditional fixed-rate triggering scheme for data acquisition in a manually scanned probe results in imaging artifacts due to variations in the scan velocity of the imaging probe. These artifacts result in a structurally inaccurate image of the sample. In this paper, we present a sensor-based manual scanning technique for OCT imaging, where real-time feedback from an optical motion sensor is used to trigger data acquisition. This technique is able to circumvent the problem of motion artifacts during manual scanning by adaptively altering the trigger rate based on the instantaneous scan velocity, enabling OCT imaging over a large lateral FOV. The feasibility of the proposed technique is demonstrated by imaging several biological and nonbiological samples.

  3. Two-axis polydimethylsiloxane-based electromagnetic microelectromechanical system scanning mirror for optical coherence tomography (United States)

    Kim, Sehui; Lee, Changho; Kim, Jin Young; Kim, Jeehyun; Lim, Geunbae; Kim, Chulhong


    Compact size and fast imaging abilities are key requirements for the clinical implementation of an optical coherence tomography (OCT) system. Among the various small-sized technology, a microelectromechanical system (MEMS) scanning mirror is widely used in a miniaturized OCT system. However, the complexities of conventional MEMS fabrication processes and relatively high costs have restricted fast clinical translation and commercialization of the OCT systems. To resolve these problems, we developed a two-axis polydimethylsiloxane (PDMS)-based MEMS (2A-PDMS-MEMS) scanning mirror through simple processes with low costs. It had a small size of 15×15×15 mm3, was fast, and had a wide scanning range at a low voltage. The AC/DC responses were measured to evaluate the performance of the 2A-PDMS-MEMS scanning mirror. The maximum scanning angles were measured as ±16.6 deg and ±11.6 deg along the X and Y axes, respectively, and the corresponding field of view was 29.8 mm×20.5 mm with an optical focal length of 50 mm. The resonance frequencies were 82 and 57 Hz along the X and Y axes, respectively. Finally, in vivo B-scan and volumetric OCT images of human fingertips and palms were successfully acquired using the developed SD-OCT system based on the 2A-PDMS-MEMS scanning mirror.

  4. Detection and analysis of multi-dimensional pulse wave based on optical coherence tomography (United States)

    Shen, Yihui; Li, Zhifang; Li, Hui; Chen, Haiyu


    Pulse diagnosis is an important method of traditional Chinese medicine (TCM). Doctors diagnose the patients' physiological and pathological statuses through the palpation of radial artery for radial artery pulse information. Optical coherence tomography (OCT) is an useful tool for medical optical research. Current conventional diagnostic devices only function as a pressure sensor to detect the pulse wave - which can just partially reflect the doctors feelings and lost large amounts of useful information. In this paper, the microscopic changes of the surface skin above radial artery had been studied in the form of images based on OCT. The deformation of surface skin in a cardiac cycle which is caused by arterial pulse is detected by OCT. The patient's pulse wave is calculated through image processing. It is found that it is good consistent with the result conducted by pulse analyzer. The real-time patient's physiological and pathological statuses can be monitored. This research provides a kind of new method for pulse diagnosis of traditional Chinese medicine.

  5. Overlapped optics induced perfect coherent effects (United States)

    Li, Jian Jie; Zang, Xiao Fei; Mao, Jun Fa; Tang, Min; Zhu, Yi Ming; Zhuang, Song Lin


    For traditional coherent effects, two separated identical point sources can be interfered with each other only when the optical path difference is integer number of wavelengths, leading to alternate dark and bright fringes for different optical path difference. For hundreds of years, such a perfect coherent condition seems insurmountable. However, in this paper, based on transformation optics, two separated in-phase identical point sources can induce perfect interference with each other without satisfying the traditional coherent condition. This shifting illusion media is realized by inductor-capacitor transmission line network. Theoretical analysis, numerical simulations and experimental results are performed to confirm such a kind of perfect coherent effect and it is found that the total radiation power of multiple elements system can be greatly enhanced. Our investigation may be applicable to National Ignition Facility (NIF), Inertial Confined Fusion (ICF) of China, LED lighting technology, terahertz communication, and so on.

  6. Dispersion-based stimulated Raman scattering spectroscopy, holography, and optical coherence tomography (Conference Presentation) (United States)

    Robles, Francisco E.; Fischer, Martin C.; Warren, Warren S.


    Stimulated Raman scattering (SRS) enables fast, high resolution imaging of chemical constituents important to biological structures and functional processes. While this technology has shown remarkable potential, it is currently limited to point scanning and can only probe a few Raman bands at a time. In this work we take a fundamentally different approach to detecting the small nonlinear signals based on dispersion effects that accompany the loss/gain processes in SRS. We use a modified pump-probe system (pulses with duration of ~0.5 ps and 75 fs, respectively) with interferometric detection in the Fourier-domain to demonstrate that the dispersive measurements are more robust to noise (e.g., laser noise) compared to conventional amplitude measurements, which in turn permits facile spectral and spatial multiplexing. Results show that it is possible to assess a broadband dispersion spectrum (currently limited to ~400 cm-1) with a single laser shot or spectrometer acquisition (20-50 µs). For molecular imaging with broadband spectral information, we achieve spatial pixel rates of 2.5 kHz, and will discuss how this can be further improved to 20-50 kHz. We also combine SRS with optical coherence tomography (OCT) (molecular and structural information are rendered from the same data), which enables axial multiplexing by coherence gating and paves the way for volumetric biochemical imaging. The approach is tested on a thin water-and-oil phantom, a thick scattering polystyrene bead phantom, and thick freshly excised human adipose tissue. Finally, we will outline other opportunities for spatial multiplexing using wide-field holography and spectroscopic-OCT, which would massively parallelize the spatial and spectral information. The combination of dispersion-based SRS and phase imaging has the potential to enable faster wide-area and volumetric molecular imaging. Such methods would be valuable in a clinical setting for many applications.

  7. Optical parametric oscillator-based light source for coherent Raman scattering microscopy: practical overview (United States)

    Brustlein, Sophie; Ferrand, Patrick; Walther, Nico; Brasselet, Sophie; Billaudeau, Cyrille; Marguet, Didier; Rigneault, Hervé


    We present the assets and constraints of using optical parametric oscillators (OPOs) to perform point scanning nonlinear microscopy and spectroscopy with special emphasis on coherent Raman spectroscopy. The difterent possible configurations starting with one OPO and two OPOs are described in detail and with comments that are intended to be practically useful for the user. Explicit examples on test samples such as nonlinear organic crystal, polystyrene beads, and fresh mouse tissues are given. Special emphasis is given to background-free coherent Raman anti-Stokes scattering (CARS) imaging, including CARS hyperspectral imaging in a fully automated mode with commercial OPOs.

  8. MEMS-based handheld fourier domain Doppler optical coherence tomography for intraoperative microvascular anastomosis imaging.

    Directory of Open Access Journals (Sweden)

    Yong Huang

    Full Text Available To demonstrate the feasibility of a miniature handheld optical coherence tomography (OCT imager for real time intraoperative vascular patency evaluation in the setting of super-microsurgical vessel anastomosis.A novel handheld imager Fourier domain Doppler optical coherence tomography based on a 1.3-µm central wavelength swept source for extravascular imaging was developed. The imager was minimized through the adoption of a 2.4-mm diameter microelectromechanical systems (MEMS scanning mirror, additionally a 12.7-mm diameter lens system was designed and combined with the MEMS mirror to achieve a small form factor that optimize functionality as a handheld extravascular OCT imager. To evaluate in-vivo applicability, super-microsurgical vessel anastomosis was performed in a mouse femoral vessel cut and repair model employing conventional interrupted suture technique as well as a novel non-suture cuff technique. Vascular anastomosis patency after clinically successful repair was evaluated using the novel handheld OCT imager.With an adjustable lateral image field of view up to 1.5 mm by 1.5 mm, high-resolution simultaneous structural and flow imaging of the blood vessels were successfully acquired for BALB/C mouse after orthotopic hind limb transplantation using a non-suture cuff technique and BALB/C mouse after femoral artery anastomosis using a suture technique. We experimentally quantify the axial and lateral resolution of the OCT to be 12.6 µm in air and 17.5 µm respectively. The OCT has a sensitivity of 84 dB and sensitivity roll-off of 5.7 dB/mm over an imaging range of 5 mm. Imaging with a frame rate of 36 Hz for an image size of 1000(lateral×512(axial pixels using a 50,000 A-lines per second swept source was achieved. Quantitative vessel lumen patency, lumen narrowing and thrombosis analysis were performed based on acquired structure and Doppler images.A miniature handheld OCT imager that can be used for intraoperative evaluation of

  9. Towards multimodal detection of melanoma thickness based on optical coherence tomography and optoacoustics (United States)

    Rahlves, M.; Varkentin, A.; Stritzel, J.; Blumenröther, E.; Mazurenka, M.; Wollweber, M.; Roth, B.


    Melanoma skin cancer has one of the highest mortality rates of all types of cancer if not detected at an early stage. The survival rate is highly dependent on its penetration depth, which is commonly determined by histopathology. In this work, we aim at combining optical coherence tomography and optoacoustic as a non-invasive all-optical method to measure the penetration depth of melanoma. We present our recent achievements to setup a handheld multimodal device and also results from first in vivo measurements on healthy and cancerous skin tissue, which are compared to measurements obtained by ultrasound and histopathology.

  10. Kernel regression based segmentation of optical coherence tomography images with diabetic macular edema. (United States)

    Chiu, Stephanie J; Allingham, Michael J; Mettu, Priyatham S; Cousins, Scott W; Izatt, Joseph A; Farsiu, Sina


    We present a fully automatic algorithm to identify fluid-filled regions and seven retinal layers on spectral domain optical coherence tomography images of eyes with diabetic macular edema (DME). To achieve this, we developed a kernel regression (KR)-based classification method to estimate fluid and retinal layer positions. We then used these classification estimates as a guide to more accurately segment the retinal layer boundaries using our previously described graph theory and dynamic programming (GTDP) framework. We validated our algorithm on 110 B-scans from ten patients with severe DME pathology, showing an overall mean Dice coefficient of 0.78 when comparing our KR + GTDP algorithm to an expert grader. This is comparable to the inter-observer Dice coefficient of 0.79. The entire data set is available online, including our automatic and manual segmentation results. To the best of our knowledge, this is the first validated, fully-automated, seven-layer and fluid segmentation method which has been applied to real-world images containing severe DME.

  11. A new optical image cryptosystem based on two-beam coherent superposition and unequal modulus decomposition (United States)

    Chen, Linfei; Gao, Xiong; Chen, Xudong; He, Bingyu; Liu, Jingyu; Li, Dan


    In this paper, a new optical image cryptosystem is proposed based on two-beam coherent superposition and unequal modulus decomposition. Different from the equal modulus decomposition or unit vector decomposition, the proposed method applies common vector decomposition to accomplish encryption process. In the proposed method, the original image is firstly Fourier transformed and the complex function in spectrum domain will be obtained. The complex distribution is decomposed into two vector components with unequal amplitude and phase by the common vector decomposition method. Subsequently, the two components are modulated by two random phases and transformed from spectrum domain to spatial domain, and amplitude parts are extracted as encryption results and phase parts are extracted as private keys. The advantages of the proposed cryptosystem are: four different phase and amplitude information created by the method of common vector decomposition strengthens the security of the cryptosystem, and it fully solves the silhouette problem. Simulation results are presented to show the feasibility and the security of the proposed cryptosystem.

  12. A novel optical coherence tomography-based micro-indentation technique for mechanical characterization of hydrogels. (United States)

    Yang, Ying; Bagnaninchi, Pierre O; Ahearne, Mark; Wang, Ruikang K; Liu, Kuo-Kang


    Depth-sensing micro-indentation has been well recognized as a powerful tool for characterizing mechanical properties of solid materials due to its non-destructive approach. Based on the depth-sensing principle, we have developed a new indentation method combined with a high-resolution imaging technique, optical coherence tomography, which can accurately measure the deformation of hydrogels under a spherical indenter at constant force. The Hertz contact theory has been applied for quantitatively correlating the indentation force and the deformation with the mechanical properties of the materials. Young's moduli of hydrogels estimated by the new method are comparable with those measured by conventional depth-sensing micro-indentation. The advantages of this new method include its capability to characterize mechanical properties of bulk soft materials and amenability to perform creeping tests. More importantly, the measurement can be performed under sterile conditions allowing non-destructive, in situ and real-time investigations on the changes in mechanical properties of soft materials (e.g. hydrogel). This unique character can be applied for various biomechanical investigations such as monitoring reconstruction of engineered tissues.

  13. Optical coherence refractometry. (United States)

    Tomlins, Peter H; Woolliams, Peter; Hart, Christian; Beaumont, Andrew; Tedaldi, Matthew


    We introduce a novel approach to refractometry using a low coherence interferometer at multiple angles of incidence. We show that for plane parallel samples it is possible to measure their phase refractive index rather than the group index that is usually measured by interferometric methods. This is a significant development because it enables bulk refractive index measurement of scattering and soft samples, not relying on surface measurements that can be prone to error. Our technique is also noncontact and compatible with in situ refractive index measurements. Here, we demonstrate this new technique on a pure silica test piece and a highly scattering resin slab, comparing the results with standard critical angle refractometry.

  14. VCSEL Based Coherent PONs

    DEFF Research Database (Denmark)

    Jensen, Jesper Bevensee; Rodes, Roberto; Caballero Jambrina, Antonio;


    We present a review of research performed in the area of coherent access technologies employing vertical cavity surface emitting lasers (VCSELs). Experimental demonstrations of optical transmission over a passive fiber link with coherent detection using VCSEL local oscillators and directly modula...

  15. Optical coherence in astrophysics

    CERN Document Server

    Moret-Bailly, Jacques


    Many physicists and most astrophysicists assume that the photon is a small particle which, in a very low pressure gas can only interact with a single molecule. Thus, the interaction of light with this gas is incoherent. W. E.Lamb Jr, W. P. Schleich, M. O. Scully and C. H. Townes (Reviews of Modern Physics 71, S263, 1999) have criticized this view: In accordance with quantum electrodynamics the photon is a pseudo-particle resulting from the quantization of a deterministic exchange of energy between identical molecules and a normal mode of electromagnetic field. Following Lamb et al., we study models in which some variables have an unusual value for a spectroscopist: extremely low pressure hydrogen, but huge light paths, extremely hot sources. However, the magnitudes of the spectral radiances and column densities can be similar in astrophysics and in a laboratory using lasers. Thus, several coherent effects must be taken into account: superradiance, multiphoton interactions, impulsive stimulated Raman scatterin...

  16. Audio frequency in vivo optical coherence elastography

    Energy Technology Data Exchange (ETDEWEB)

    Adie, Steven G; Kennedy, Brendan F; Armstrong, Julian J; Alexandrov, Sergey A; Sampson, David D [Optical-Biomedical Engineering Laboratory (OBEL), School of Electrical, Electronic and Computer Engineering, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009 (Australia)], E-mail:


    We present a new approach to optical coherence elastography (OCE), which probes the local elastic properties of tissue by using optical coherence tomography to measure the effect of an applied stimulus in the audio frequency range. We describe the approach, based on analysis of the Bessel frequency spectrum of the interferometric signal detected from scatterers undergoing periodic motion in response to an applied stimulus. We present quantitative results of sub-micron excitation at 820 Hz in a layered phantom and the first such measurements in human skin in vivo.

  17. Optics for coherent X-ray applications



    Developments of X-ray optics for full utilization of diffraction-limited storage rings (DLSRs) are presented. The expected performance of DLSRs is introduced using the design parameters of SPring-8 II. To develop optical elements applicable to manipulation of coherent X-rays, advanced technologies on precise processing and metrology were invented. With propagation-based coherent X-rays at the 1 km beamline of SPring-8, a beryllium window fabricated with the physical-vapour-deposition method w...

  18. Wireless, Web-Based Interactive Control of Optical Coherence Tomography with Mobile Devices (United States)

    Mehta, Rajvi; Nankivil, Derek; Zielinski, David J.; Waterman, Gar; Keller, Brenton; Limkakeng, Alexander T.; Kopper, Regis; Izatt, Joseph A.; Kuo, Anthony N.


    Purpose Optical coherence tomography (OCT) is widely used in ophthalmology clinics and has potential for more general medical settings and remote diagnostics. In anticipation of remote applications, we developed wireless interactive control of an OCT system using mobile devices. Methods A web-based user interface (WebUI) was developed to interact with a handheld OCT system. The WebUI consisted of key OCT displays and controls ported to a webpage using HTML and JavaScript. Client–server relationships were created between the WebUI and the OCT system computer. The WebUI was accessed on a cellular phone mounted to the handheld OCT probe to wirelessly control the OCT system. Twenty subjects were imaged using the WebUI to assess the system. System latency was measured using different connection types (wireless 802.11n only, wireless to remote virtual private network [VPN], and cellular). Results Using a cellular phone, the WebUI was successfully used to capture posterior eye OCT images in all subjects. Simultaneous interactivity by a remote user on a laptop was also demonstrated. On average, use of the WebUI added only 58, 95, and 170 ms to the system latency using wireless only, wireless to VPN, and cellular connections, respectively. Qualitatively, operator usage was not affected. Conclusions Using a WebUI, we demonstrated wireless and remote control of an OCT system with mobile devices. Translational Relevance The web and open source software tools used in this project make it possible for any mobile device to potentially control an OCT system through a WebUI. This platform can be a basis for remote, teleophthalmology applications using OCT.

  19. Fast and automatic depth control of iterative bone ablation based on optical coherence tomography data (United States)

    Fuchs, Alexander; Pengel, Steffen; Bergmeier, Jan; Kahrs, Lüder A.; Ortmaier, Tobias


    Laser surgery is an established clinical procedure in dental applications, soft tissue ablation, and ophthalmology. The presented experimental set-up for closed-loop control of laser bone ablation addresses a feedback system and enables safe ablation towards anatomical structures that usually would have high risk of damage. This study is based on combined working volumes of optical coherence tomography (OCT) and Er:YAG cutting laser. High level of automation in fast image data processing and tissue treatment enables reproducible results and shortens the time in the operating room. For registration of the two coordinate systems a cross-like incision is ablated with the Er:YAG laser and segmented with OCT in three distances. The resulting Er:YAG coordinate system is reconstructed. A parameter list defines multiple sets of laser parameters including discrete and specific ablation rates as ablation model. The control algorithm uses this model to plan corrective laser paths for each set of laser parameters and dynamically adapts the distance of the laser focus. With this iterative control cycle consisting of image processing, path planning, ablation, and moistening of tissue the target geometry and desired depth are approximated until no further corrective laser paths can be set. The achieved depth stays within the tolerances of the parameter set with the smallest ablation rate. Specimen trials with fresh porcine bone have been conducted to prove the functionality of the developed concept. Flat bottom surfaces and sharp edges of the outline without visual signs of thermal damage verify the feasibility of automated, OCT controlled laser bone ablation with minimal process time.

  20. High-order polarization mode crosstalk effect: a calibration scheme of white light-based optical coherence domain polarimetry (United States)

    Wu, Bing; Yang, Jun; Zhang, Jianzhong; Liang, Shuai; Yu, Zhangjun; Yuan, Yonggui; Peng, Feng; Zhou, Ai; Zhang, Yu; Yuan, Libo


    We propose a calibration scheme of the white light interferometer based optical coherence domain polarimetry (OCDP), which could be used to measure the ultra-weak polarization mode crosstalk (PMC) or the ultra-high polarization extinction ratio (PER) of different polarization optical devices. The calibration depends on the first and second order PMC effect of different polarization devices in series. The first and second PMCs between 0 and -90dB, established by five pieces of polarization maintaining fiber (PMF) and a Y-waveguide, is used to prove its feasibility.

  1. Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Mogensen, Mette; Themstrup, Lotte; Banzhaf, Christina;


    as the optical analogue to ultrasound. The inherent safety of the technology allows for in vivo use of OCT in patients. The main strength of OCT is the depth resolution. In dermatology, most OCT research has turned on non-melanoma skin cancer (NMSC) and non-invasive monitoring of morphological changes...... tissue after therapy. The OCT images provide an advantageous combination of resolution and penetration depth, but specific studies of diagnostic sensitivity and specificity in dermatology are sparse. In order to improve OCT image quality and expand the potential of OCT, technical developments...... are necessary. It is suggested that the technology will be of particular interest to the routine follow-up of patients undergoing non-invasive therapy of malignant or premalignant keratinocyte tumours. It is speculated that the continued technological development can propel the method to a greater level...

  2. Coherence Constraints and the Last Hidden Optical Coherence

    CERN Document Server

    Qian, Xiao-Feng; Vamivakas, A Nick; Eberly, Joseph H


    We have discovered a new domain of optical coherence, and show that it is the third and last member of a previously unreported fundamental triad of coherences. These are unified by our derivation of a parallel triad of coherence constraints that take the form of complementarity relations. We have been able to enter this new coherence domain experimentally and we describe the novel tomographic approach devised for that purpose.

  3. Optical coherence tomography in conjunction with bronchoscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Ascedio Jose; Takimura, Celso Kiyochi; Lemos Neto, Pedro Alves; Figueiredo, Viviane Rossi, E-mail: [Servico de Endoscopia Respiratoria, Hospital das Clinicas, Universidade de Sao Paulo (FM/USP), SP (Brazil)


    To evaluate the feasibility of and the potential for using optical coherence tomography in conjunction with conventional bronchoscopy in the evaluation of the airways. Methods: This was a pilot study based on an ex vivo experimental model involving three animals: one adult New Zealand rabbit and two Landrace pigs. An optical coherence tomography imaging catheter was inserted through the working channel of a flexible bronchoscope in order to reach the distal trachea of the animals. Images of the walls of the trachea were systematically taken along its entire length, from the distal to the proximal portion. Results: The imaging catheter was easily adapted to the working channel of the bronchoscope. High-resolution images of cross sections of the trachea were taken in real time, precisely delineating microstructures, such as the epithelium, submucosa, and cartilage, as well as the adventitia of the anterior and lateral tracheal walls. The corresponding layers of the epithelium, mucosa, and cartilage were clearly differentiated. The mucosa, submucosa, and trachealis muscle were clearly identified in the posterior wall. Conclusions: It is feasible to use an optical coherence tomography imaging catheter in combination with a flexible bronchoscope. Optical coherence tomography produces high resolution images that reveal the microanatomy of the trachea, including structures that are typically seen only on images produced by conventional histology. (author)

  4. Prostate cancer diagnosis: the feasibility of needle-based optical coherence tomography. (United States)

    Muller, Berrend G; de Bruin, Daniel M; van den Bos, Willemien; Brandt, Martin J; Velu, Juliette F; Bus, Mieke T J; Faber, Dirk J; Savci, Dilara; Zondervan, Patricia J; de Reijke, Theo M; Pes, Pilar Laguna; de la Rosette, Jean; van Leeuwen, Ton G


    The objective of this study is to demonstrate the feasibility of needle-based optical coherence tomography (OCT) and functional analysis of OCT data along the full pullback trajectory of the OCT measurement in the prostate, correlated with pathology. OCT images were recorded using a commercially available C7-XR™ OCT Intravascular Imaging System interfaced to a C7 Dragonfly™ intravascular 0.9-mm-diameter imaging probe. A computer program was constructed for automated image attenuation analysis. First, calibration of the OCT system for both the point spread function and the system roll-off was achieved by measurement of the OCT signal attenuation from an extremely weakly scattering medium (Intralipid® 0.0005 volume%). Second, the data were arranged in 31 radial wedges (pie slices) per circular segments consisting of 16 A-scans per wedge and 5 axial B-scans, resulting in an average A-scan per wedge. Third, the decay of the OCT signal is analyzed over 50 pixels ([Formula: see text]) in depth, starting from the first found maximum data point. Fourth, for visualization, the data were grouped with a corresponding color representing a specific [Formula: see text] range according to their attenuation coefficient. Finally, the analyses were compared to histopathology. To ensure that each single use sterile imaging probe is comparable to the measurements of the other imaging probes, the probe-to-probe variations were analyzed by measuring attenuation coefficients of 0.03, 6.5, 11.4, 17, and 22.7 volume% Intralipid®. Experiments were repeated five times per probe for four probes. Inter- and intraprobe variation in the measured attenuation of Intralipid samples with scattering properties similar to that of the prostate was [Formula: see text] of the mean values. Mean attenuation coefficients in the prostate were [Formula: see text] for parts of the tissue that were classified as benign (SD: [Formula: see text], minimum: [Formula: see text], maximum: [Formula: see text

  5. Wide-field optical coherence tomography based microangiography for retinal imaging (United States)

    Zhang, Qinqin; Lee, Cecilia S.; Chao, Jennifer; Chen, Chieh-Li; Zhang, Thomas; Sharma, Utkarsh; Zhang, Anqi; Liu, Jin; Rezaei, Kasra; Pepple, Kathryn L.; Munsen, Richard; Kinyoun, James; Johnstone, Murray; van Gelder, Russell N.; Wang, Ruikang K.


    Optical coherence tomography angiography (OCTA) allows for the evaluation of functional retinal vascular networks without a need for contrast dyes. For sophisticated monitoring and diagnosis of retinal diseases, OCTA capable of providing wide-field and high definition images of retinal vasculature in a single image is desirable. We report OCTA with motion tracking through an auxiliary real-time line scan ophthalmoscope that is clinically feasible to image functional retinal vasculature in patients, with a coverage of more than 60 degrees of retina while still maintaining high definition and resolution. We demonstrate six illustrative cases with unprecedented details of vascular involvement in retinal diseases. In each case, OCTA yields images of the normal and diseased microvasculature at all levels of the retina, with higher resolution than observed with fluorescein angiography. Wide-field OCTA technology will be an important next step in augmenting the utility of OCT technology in clinical practice.

  6. Optical coherence tomography-based topography determination of corneal grafts in eye bank cultivation (United States)

    Damian, Angela; Seitz, Berthold; Langenbucher, Achim; Eppig, Timo


    Vision loss due to corneal injuries or diseases can be treated by transplantation of human corneal grafts (keratoplasty). However, quality assurance in retrieving and cultivating the tissue transplants is confined to visual and microbiological testing. To identify previous refractive surgery or morphological alterations, an automatic, noncontact, sterile screening procedure is required. Twenty-three corneal grafts have been measured in organ culture with a clinical spectral-domain optical coherence tomographer. Employing a biconic surface fit with 10 degrees of freedom, the radii of curvature and conic constants could be estimated for the anterior and posterior corneal surfaces. Thereupon, central corneal thickness, refractive values, and astigmatism have been calculated. Clinical investigations are required to elaborate specific donor-host matching in the future.

  7. Stokes Space-Based Optical Modulation Format Recognition for Digital Coherent Receivers

    DEFF Research Database (Denmark)

    Borkowski, Robert; Zibar, Darko; Caballero Jambrina, Antonio;


    We present a technique for modulation format recognition for heterogeneous reconfigurable optical networks. The method is based on Stokes space signal representation and uses a variational Bayesian expectation maximization machine learning algorithm. Differentiation between diverse common coheren...

  8. Noninvasive monitoring of glucose concentration using differential absorption low-coherence interferometry based on rapid scanning optical delay line

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Yong; Zeng Nan; He Yonghong, E-mail: [Laboratory of Optical Imaging and Sensing, Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055 (China)


    A non-invasive method of detecting glucose concentration using differential absorption low-coherence interferometry (DALCI) based on rapid scanning optical delay line is presented. Two light sources, one centered within (1625 nm) a glucose absorption band, while the other outside (1310 nm) the glucose absorption band, are used in the experiment. The low-coherence interferometry (LCI) is employed to obtain the signals back-reflecting from the iris which carries the messages of material concentration in anterior chamber. Using rapid scanning optical delay line (RSOD) as the reference arm, we can detect the signals in a very short time. Therefore the glucose concentration can be monitored in real-time, which is very important for the detection in vivo. In our experiments, the cornea and aqueous humor can be treated as nearly non-scattering substance. The difference in the absorption coefficient is much larger than the difference in the scattering coefficient, so the influence of scattering can be neglected. By subtracting the algorithmic low-coherence interference signals of the two wavelengths, the absorption coefficient can be calculated which is proportional to glucose concentration. To reduce the speckle noise, a 30 variation of signals were used before the final calculation of the glucose concentration. The improvements of our experiment are also discussed in the article. The method has a potential application for noninvasive detection of glucose concentration in vivo and in real-time.

  9. General model of signal propagation in a Raman amplified single-mode fiber based coherent optical communication system (United States)

    Cheng, Jingchi; Tang, Ming; Fu, Songnian; Shum, Perry Ping; Liu, Deming


    The distributed Raman amplifier (DRA) has been widely utilized in state-of-the-art coherent optical communication systems using multi-level modulation formatted signals in order to improve transmission performance. A general model based on Jones vector notation governing the signal propagation under Raman amplified link is proposed. Primary physics including both linear and nonlinear effects have been taken into account. The numerical approach for solving the equations is illustrated in detail. Using the model, system characterization and optimization can be easily performed. We also compare our model with the commonly used coarse-step method. It is found that the coarse-step method will exaggerate the cross-polarization modulation induced impairments by over 6 dB and will become unusable when the pump power is as high as several Watts. The proposed model provides a guideline for the simulation of Raman amplified coherent transmission systems.

  10. Comprehensive vascular imaging using optical coherence tomography-based angiography and photoacoustic tomography (United States)

    Zabihian, Behrooz; Chen, Zhe; Rank, Elisabet; Sinz, Christoph; Bonesi, Marco; Sattmann, Harald; Ensher, Jason; Minneman, Michael P.; Hoover, Erich; Weingast, Jessika; Ginner, Laurin; Leitgeb, Rainer; Kittler, Harald; Zhang, Edward; Beard, Paul; Drexler, Wolfgang; Liu, Mengyang


    Studies have proven the relationship between cutaneous vasculature abnormalities and dermatological disorders, but to image vasculature noninvasively in vivo, advanced optical imaging techniques are required. In this study, we imaged a palm of a healthy volunteer and three subjects with cutaneous abnormalities with photoacoustic tomography (PAT) and optical coherence tomography with angiography extension (OCTA). Capillaries in the papillary dermis that are too small to be discerned with PAT are visualized with OCTA. From our results, we speculate that the PA signal from the palm is mostly from hemoglobin in capillaries rather than melanin, knowing that melanin concentration in volar skin is significantly smaller than that in other areas of the skin. We present for the first time OCTA images of capillaries along with the PAT images of the deeper vessels, demonstrating the complementary effective imaging depth range and the visualization capabilities of PAT and OCTA for imaging human skin in vivo. The proposed imaging system in this study could significantly improve treatment monitoring of dermatological diseases associated with cutaneous vasculature abnormalities.

  11. A high-efficiency fiber-based imaging system for co-registered autofluorescence and optical coherence tomography. (United States)

    Pahlevaninezhad, Hamid; Lee, Anthony M D; Shaipanich, Tawimas; Raizada, Rashika; Cahill, Lucas; Hohert, Geoffrey; Yang, Victor X D; Lam, Stephen; MacAulay, Calum; Lane, Pierre


    We present a power-efficient fiber-based imaging system capable of co-registered autofluorescence imaging and optical coherence tomography (AF/OCT). The system employs a custom fiber optic rotary joint (FORJ) with an embedded dichroic mirror to efficiently combine the OCT and AF pathways. This three-port wavelength multiplexing FORJ setup has a throughput of more than 83% for collected AF emission, significantly more efficient compared to previously reported fiber-based methods. A custom 900 µm diameter catheter ‒ consisting of a rotating lens assembly, double-clad fiber (DCF), and torque cable in a stationary plastic tube ‒ was fabricated to allow AF/OCT imaging of small airways in vivo. We demonstrate the performance of this system ex vivo in resected porcine airway specimens and in vivo in human on fingers, in the oral cavity, and in peripheral airways.

  12. Optics for coherent X-ray applications

    Energy Technology Data Exchange (ETDEWEB)

    Yabashi, Makina, E-mail: [RIKEN SPring-8 Center, Kouto 1-1-1, Sayo, Hyogo 679-5148 (Japan); Tono, Kensuke [Japan Synchrotron Radiation Research Institute (JASRI), Kouto 1-1-1, Sayo, Hyogo 679-5198 (Japan); Mimura, Hidekazu [The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656 (Japan); Matsuyama, Satoshi; Yamauchi, Kazuto [Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Tanaka, Takashi; Tanaka, Hitoshi; Tamasaku, Kenji [RIKEN SPring-8 Center, Kouto 1-1-1, Sayo, Hyogo 679-5148 (Japan); Ohashi, Haruhiko; Goto, Shunji [Japan Synchrotron Radiation Research Institute (JASRI), Kouto 1-1-1, Sayo, Hyogo 679-5198 (Japan); Ishikawa, Tetsuya [RIKEN SPring-8 Center, Kouto 1-1-1, Sayo, Hyogo 679-5148 (Japan)


    Developments of optics for coherent X-ray applications and their role in diffraction-limited storage rings are described. Developments of X-ray optics for full utilization of diffraction-limited storage rings (DLSRs) are presented. The expected performance of DLSRs is introduced using the design parameters of SPring-8 II. To develop optical elements applicable to manipulation of coherent X-rays, advanced technologies on precise processing and metrology were invented. With propagation-based coherent X-rays at the 1 km beamline of SPring-8, a beryllium window fabricated with the physical-vapour-deposition method was found to have ideal speckle-free properties. The elastic emission machining method was utilized for developing reflective mirrors without distortion of the wavefronts. The method was further applied to production of diffraction-limited focusing mirrors generating the smallest spot size in the sub-10 nm regime. To enable production of ultra-intense nanobeams at DLSRs, a low-vibration cooling system for a high-heat-load monochromator and advanced diagnostic systems to characterize X-ray beam properties precisely were developed. Finally, new experimental schemes for combinative nano-analysis and spectroscopy realised with novel X-ray optics are discussed.

  13. 3D Curvelet-Based Segmentation and Quantification of Drusen in Optical Coherence Tomography Images

    Directory of Open Access Journals (Sweden)

    M. Esmaeili


    Full Text Available Spectral-Domain Optical Coherence Tomography (SD-OCT is a widely used interferometric diagnostic technique in ophthalmology that provides novel in vivo information of depth-resolved inner and outer retinal structures. This imaging modality can assist clinicians in monitoring the progression of Age-related Macular Degeneration (AMD by providing high-resolution visualization of drusen. Quantitative tools for assessing drusen volume that are indicative of AMD progression may lead to appropriate metrics for selecting treatment protocols. To address this need, a fully automated algorithm was developed to segment drusen area and volume from SD-OCT images. The proposed algorithm consists of three parts: (1 preprocessing, which includes creating binary mask and removing possible highly reflective posterior hyaloid that is used in accurate detection of inner segment/outer segment (IS/OS junction layer and Bruch’s membrane (BM retinal layers; (2 coarse segmentation, in which 3D curvelet transform and graph theory are employed to get the possible candidate drusenoid regions; (3 fine segmentation, in which morphological operators are used to remove falsely extracted elongated structures and get the refined segmentation results. The proposed method was evaluated in 20 publically available volumetric scans acquired by using Bioptigen spectral-domain ophthalmic imaging system. The average true positive and false positive volume fractions (TPVF and FPVF for the segmentation of drusenoid regions were found to be 89.15% ± 3.76 and 0.17% ± .18%, respectively.

  14. Fiber-optic ground settlement sensor based on low-coherent interferometry. (United States)

    Zhang, Pinglei; Wei, Heming; Zhao, Xuefeng; Sun, Changsen


    Ground settlement (GS) monitoring is a basic prerequisite in civil engineering. A commercialized instrument to meet this requirement has been available with millimeter accuracy. Major difficulties to improve this to micrometer scale, which are needed in special cases such as in high-speed railways, are challenged by the long stability of the sensor in the condition of the extremely slow settlement. A fiber-optic GS methodology was proposed by using a scanning low-coherent Michelson interferometer. One of the paths of the interferometer is formed by the liquid surface, and therefore the readout of the interferometer can make the measurement of the surface approach a micrometer scale. The liquid-contained chambers are hydraulically connected together at the bottom by using a water-filled tube. The liquid surface inside each chamber is at the same level initially. One of the chambers is located on stable ground or at a point that can be easily surveyed, too. The others are located at the points where settlement or heave is to be measured. Differential settlement, or heave, between the chambers will result in an apparent rise or fall of the liquid level, which biased the initial equal status. The experimental results demonstrated that the best accuracy of ±20  μm for GS monitoring was obtained with a reference compensation sensor.

  15. Ultra-thin and flexible endoscopy probe for optical coherence tomography based on stepwise transitional core fiber. (United States)

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


    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.

  16. A gel-based skin and blood flow model for a Doppler optical coherence tomography (DOCT) imaging system (United States)

    Lawlor, Kate; O'Connell, Marie-Louise; Jonathan, Enock; Leahy, Martin J.


    Since its discovery in 1842 by Christian Johann Doppler, the Doppler Effect has had many applications in the scientific world. In recent years, the phenomenon has been integrated with Optical Coherence Tomography (OCT) yielding Doppler Optical Coherence Tomography (DOCT), a technique that is useful for high-resolution imaging of the skin microcirculation. However, interpretation of DOCT images is rather challenging. Thus, our study aims to aid understanding of DOCT images with respect to parameters of microcirculation components such as blood vessel size, depth and angular position. To this end, we have constructed a gel-based tissue and blood-flow model for performing DOCT studies under well controlled conditions. We present results from a pilot study using a gel-based tissue and blood flow model. Human blood was pumped through the model at various velocities from a commercial calibrated syringe pump, serving as a standard reference point for all velocity measurements. The range of velocity values was chosen to coincide with that found in the human vasculature. Simultaneous DOCT imaging at different flow rates contributed to establishing the capabilities and limitations of the DOCT system under investigation. We present preliminary results as first step to developing a robust validation protocol with which to aid future research in this area.

  17. Imaging granulomatous lesions with optical coherence tomography

    DEFF Research Database (Denmark)

    Banzhaf, Christina; Jemec, Gregor B E


    To investigate and compare the presentation of granulomatous lesions in optical coherence tomography (OCT) images and compare this to previous studies of nonmelanoma skin tumors.......To investigate and compare the presentation of granulomatous lesions in optical coherence tomography (OCT) images and compare this to previous studies of nonmelanoma skin tumors....

  18. Optical coherence tomography in dermatology (United States)

    Sattler, Elke; Kästle, Raphaela; Welzel, Julia


    Optical coherence tomography (OCT) is a noninvasive diagnostic method that offers a view into the superficial layers of the skin in vivo in real-time. An infrared broadband light source allows the investigation of skin architecture and changes up to a depth of 1 to 2 mm with a resolution between 15 and 3 μm, depending on the system used. Thus OCT enables evaluation of skin lesions, especially nonmelanoma skin cancers and inflammatory diseases, quantification of skin changes, visualization of parasitic infestations, and examination of other indications such as the investigation of nails. OCT provides a quick and useful diagnostic imaging technique for a number of clinical questions and is a valuable addition or complement to other noninvasive imaging tools such as dermoscopy, high-frequency ultrasound, and confocal laser scan microscopy.

  19. 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


    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.

  20. Progress in hollow core photonic crystal fiber for atomic vapour based coherent optics (United States)

    Bradley, T. D.; Wang, Y. Y.; Alharbi, M.; Fourcade Dutin, C.; Mangan, B. J.; Wheeler, N. V.; Benabid, F.


    We report on progress in different hollow core photonic crystal fiber (HC-PCF) design and fabrication for atomic vapor based applications. We have fabricated a Photonic bandgap (PBG) guiding HC-PCF with a record loss of 107dB/km at 785nm in this class of fiber. A double photonic bandgap (DPBG) guiding HC-PCF with guidance bands centred at 780nm and 1064nm is reported. A 7-cell 3-ring Kagome HC-PCF with hypocycloid core is reported, the optical loss at 780nm has been reduced to 70dB/km which to the best of our knowledge is the lowest optical loss reported at this wavelength using HC-PCF. Details on experimental loading of alkali metal vapours using a far off red detuned laser are reported. This optical loading has been shown to decrease the necessary loading time for Rb into the hollow core of a fiber. The quantity of Rb within the fiber core has been enhanced by a maximum of 14% through this loading procedure.

  1. Experimental demonstration of coherent feedback control on optical field squeezing

    CERN Document Server

    Iida, Sanae; Yonezawa, Hidehiro; Yamamoto, Naoki; Furusawa, Akira


    Coherent feedback is a non-measurement based, hence a back-action free, method of control for quantum systems. A typical application of this control scheme is squeezing enhancement, a purely non-classical effect in quantum optics. In this paper we report its first experimental demonstration that well agrees with the theory taking into account time delays and losses in the coherent feedback loop. The results clarify both the benefit and the limitation of coherent feedback control in a practical situation.

  2. High-dynamic-range microscope imaging based on exposure bracketing in full-field optical coherence tomography. (United States)

    Leong-Hoi, Audrey; Montgomery, Paul C; Serio, Bruno; Twardowski, Patrice; Uhring, Wilfried


    By applying the proposed high-dynamic-range (HDR) technique based on exposure bracketing, we demonstrate a meaningful reduction in the spatial noise in image frames acquired with a CCD camera so as to improve the fringe contrast in full-field optical coherence tomography (FF-OCT). This new signal processing method thus allows improved probing within transparent or semitransparent samples. The proposed method is demonstrated on 3 μm thick transparent polymer films of Mylar, which, due to their transparency, produce low contrast fringe patterns in white-light interference microscopy. High-resolution tomographic analysis is performed using the technique. After performing appropriate signal processing, resulting XZ sections are observed. Submicrometer-sized defects can be lost in the noise that is present in the CCD images. With the proposed method, we show that by increasing the signal-to-noise ratio of the images, submicrometer-sized defect structures can thus be detected.

  3. Second-harmonic optical coherence tomography (United States)

    Jiang, Yi; Tomov, Ivan; Wang, Yimin; Chen, Zhongping


    Second-harmonic optical coherence tomography, which uses coherence gating of second-order nonlinear optical responses of biological tissues for imaging, is described and demonstrated. Femtosecond laser pulses were used to excite second-harmonic waves from collagen harvested from rat tail tendon and a reference nonlinear crystal. Second-harmonic interference fringe signals were detected and used for image construction. Because of the strong dependence of second-harmonic generation on molecular and tissue structures, this technique imparts contrast and resolution enhancement to conventional optical coherence tomography.

  4. Ex vivo imaging of human thyroid pathology using integrated optical coherence tomography and optical coherence microscopy (United States)

    Zhou, Chao; Wang, Yihong; Aguirre, Aaron D.; Tsai, Tsung-Han; Cohen, David W.; Connolly, James L.; Fujimoto, James G.


    We evaluate the feasibility of optical coherence tomography (OCT) and optical coherence microscopy (OCM) for imaging of benign and malignant thyroid lesions ex vivo using intrinsic optical contrast. 34 thyroid gland specimens are imaged from 17 patients, covering a spectrum of pathology ranging from normal thyroid to benign disease/neoplasms (multinodular colloid goiter, Hashimoto's thyroiditis, and follicular adenoma) and malignant thyroid tumors (papillary carcinoma and medullary carcinoma). Imaging is performed using an integrated OCT and OCM system, with tumor cells, can be identified from OCT and OCM images and are clearly differentiable from normal or benign thyroid tissues. With further development of needle-based imaging probes, OCT and OCM could be promising techniques to use for the screening of thyroid nodules and to improve the diagnostic specificity of fine needle aspiration evaluation.

  5. Optical Coherence Tomography Angiography in Fovea Plana. (United States)

    Dolz-Marco, Rosa; Phasukkijwatana, Nopasak; Sarraf, David; Freund, K Bailey


    Fovea plana is characterized by the anatomical absence of the foveal pit in eyes with normal visual function. The authors have analyzed three cases of idiopathic fovea plana with optical coherence tomography angiography (OCTA). As previously reported, the authors found the absence of a foveal avascular zone in all cases with OCTA; however, a preserved fusion of both the superficial and the deep capillary plexuses was found around the foveal center. This novel observation cannot be detected with conventional dye-based angiography, in which the deep capillary plexus is not visualized. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:670-673.].

  6. Optical Coherence Tomography (OCT) in ophthalmology: introduction. (United States)

    Fujimoto, James G; Drexler, Wolfgang; Schuman, Joel S; Hitzenberger, Christoph K


    The Optical Society (OSA) is pleased to present this special issue of Optics Express on "Optical Coherence Tomography (OCT) in Ophthalmology" as part of the new Interactive Science Publishing (ISP) project. The project is being performed in collaboration with the National Library of Medicine and represents a new paradigm for the publication of digital image and large dataset information.

  7. Low coherence technique to interrogate optical sensors based on selectively filled double-core photonic crystal fiber for temperature measurement (United States)

    Li, Kun; Jiang, Meng; Zhao, Zhongze; Wang, Zeming


    In this paper, an optical fiber sensing system based on low coherence interferometry (LCI) is proposed and demonstrated to interrogate sensors comprised of selectively filled double-core photonic crystal fiber (SFDC-PCF). The sensor used here is made by selectively filling about 1/3 area of air holes in the cladding of photonic crystal fiber with distilled water. So the dual-core in the sensor has different effective refractive indices, resulting in a phase delay between two lights transmitting in the fiber. The phase delay of the sensor can be compensated by a Mach-Zehnder interferometer with a scanning optical tunable delay line in one arm of the interferometer, namely temporal interrogation. By tracking the value of phase delay, the change of the measurand can be detected. Temperature measurement is carried out to testify the system performance. An average sensitivity of 0.9 μm/°C is achieved within the temperature range of 29-92 °C. This work provides a new thinking for fiber sensing technology based on LCI. The proposed all-fiber sensing system, with the merits of cost-effective, stability, and flexibility, can demodulate the SFDC-PCF sensor signals well. Further improvements such as better sensitivity, larger measurement range and multiplexing efficiency can be realized by tailoring the PCF sensor's structure.

  8. Normative data of outer photoreceptor layer thickness obtained by software image enhancing based on Stratus optical coherence tomography images

    DEFF Research Database (Denmark)

    Christensen, U.C.; Kroyer, K.; Thomadsen, J.


    Aim: To present normative data of outer photoreceptor layer thickness obtained by a new semiautomatic image analysis algorithm operating on contrast-enhanced optical coherence tomography (OCT) images. Methods: Eight Stratus OCT3 scans from identical retinal locations from 25 normal eyes were regi...




    Purpose Spectral domain optical coherence tomography can be used to measure both choroidal thickness and drusen load. The authors conducted an exploratory study using spectral domain optical coherence tomography to determine if a correlation between choroidal thickness and drusen load exists in patients with dry age-related macular degeneration. Methods Forty-four patients with dry age-related macular degeneration were recruited. The drusen area and volume were determined using the automated software algorithm of the spectral domain optical coherence tomography device, and choroidal thickness was measured using enhanced depth imaging. Correlations were determined using multivariable and univariable analyses. Results The authors found an inverse correlation between choroidal thickness and drusen load (r = −0.35, P = 0.04). Drusen load was also correlated with visual acuity (r = 0.32, P = 0.04). A correlation between choroidal thickness and visual acuity was suggested (r = −0.22, P = 0.21). Conclusion Spectral domain optical coherence tomography can be used to assess the correlation between drusen load and choroidal thickness, both of which show a relationship with visual acuity. The measurement of these outcomes may serve as important outcome parameters in routine clinical care and in clinical trials for patients with dry age-related macular degeneration. PMID:23474546

  10. Optics for coherent X-ray applications. (United States)

    Yabashi, Makina; Tono, Kensuke; Mimura, Hidekazu; Matsuyama, Satoshi; Yamauchi, Kazuto; Tanaka, Takashi; Tanaka, Hitoshi; Tamasaku, Kenji; Ohashi, Haruhiko; Goto, Shunji; Ishikawa, Tetsuya


    Developments of X-ray optics for full utilization of diffraction-limited storage rings (DLSRs) are presented. The expected performance of DLSRs is introduced using the design parameters of SPring-8 II. To develop optical elements applicable to manipulation of coherent X-rays, advanced technologies on precise processing and metrology were invented. With propagation-based coherent X-rays at the 1 km beamline of SPring-8, a beryllium window fabricated with the physical-vapour-deposition method was found to have ideal speckle-free properties. The elastic emission machining method was utilized for developing reflective mirrors without distortion of the wavefronts. The method was further applied to production of diffraction-limited focusing mirrors generating the smallest spot size in the sub-10 nm regime. To enable production of ultra-intense nanobeams at DLSRs, a low-vibration cooling system for a high-heat-load monochromator and advanced diagnostic systems to characterize X-ray beam properties precisely were developed. Finally, new experimental schemes for combinative nano-analysis and spectroscopy realised with novel X-ray optics are discussed.

  11. GPU-accelerated non-uniform fast Fourier transform-based compressive sensing spectral domain optical coherence tomography. (United States)

    Xu, Daguang; Huang, Yong; Kang, Jin U


    We implemented the graphics processing unit (GPU) accelerated compressive sensing (CS) non-uniform in k-space spectral domain optical coherence tomography (SD OCT). Kaiser-Bessel (KB) function and Gaussian function are used independently as the convolution kernel in the gridding-based non-uniform fast Fourier transform (NUFFT) algorithm with different oversampling ratios and kernel widths. Our implementation is compared with the GPU-accelerated modified non-uniform discrete Fourier transform (MNUDFT) matrix-based CS SD OCT and the GPU-accelerated fast Fourier transform (FFT)-based CS SD OCT. It was found that our implementation has comparable performance to the GPU-accelerated MNUDFT-based CS SD OCT in terms of image quality while providing more than 5 times speed enhancement. When compared to the GPU-accelerated FFT based-CS SD OCT, it shows smaller background noise and less side lobes while eliminating the need for the cumbersome k-space grid filling and the k-linear calibration procedure. Finally, we demonstrated that by using a conventional desktop computer architecture having three GPUs, real-time B-mode imaging can be obtained in excess of 30 fps for the GPU-accelerated NUFFT based CS SD OCT with frame size 2048(axial) × 1,000(lateral).

  12. Coherent optical pumping of semiconductor lasers

    Energy Technology Data Exchange (ETDEWEB)

    Pfister, M.; Dupertuis, M.A. [Inst. de Micro- et Optoelectronique, Lausanne (Switzerland). Dept. de Physique


    The influence of coherent optical pumping in semiconductor lasers is investigated theoretically. In particular the mathematical conditions under which an optically pumped system behaves like an electrically (incoherently) pumped system are derived. The authors show that it is practically impossible to reach the interesting regime where coherent effects are important because of the inherent constraints to absorb photons at the pump frequency and to reach threshold gain at the lasing frequency. The effects of changing the temperature and of reduced dimensionality are discussed.

  13. Coherent broadband light source for parallel optical coherence tomography

    NARCIS (Netherlands)

    Rivier, S.; Laversenne, L.; Bourquin, S.; Salathé, R.P.; Pollnau, M.; Grivas, C.; Shepherd, D.P.; Eason, R.W.; Flury, M.; Philipoussis, I.; Herzig, H.P.


    A Ti:sapphire planar waveguide is rib structured by Ar ion milling to provide parallel channel waveguides. By coupling high-power pump light through a microlens array into the waveguides, a novel broadband luminescent parallel emitter is demonstrated as a light source for parallel optical coherence

  14. On-chip microwave-to-optical quantum coherent converter based on a superconducting resonator coupled to an electro-optic microresonator (United States)

    Javerzac-Galy, C.; Plekhanov, K.; Bernier, N. R.; Toth, L. D.; Feofanov, A. K.; Kippenberg, T. J.


    We propose a device architecture capable of direct quantum coherent electro-optical conversion of microwave-to-optical photons. The hybrid system consists of a planar superconducting microwave circuit coupled to an integrated whispering-gallery-mode microresonator made from an electro-optical material. We show that by exploiting the large vacuum electric field of the planar microwave resonator, electro-optical (vacuum) coupling strengths g0 as large as ˜2 π O (10 -100 ) kHz are achievable with currently available technology—a more than 3 orders of magnitude improvement over prior designs and realizations. Operating at millikelvin temperatures, such a converter would enable high-efficiency conversion of microwave-to-optical photons. We analyze the added noise and show that maximum quantum coherent conversion efficiency is achieved for a multiphoton cooperativity of unity which can be reached with optical power as low as O (1 ) mW.

  15. DSP Based PMD Emulators for Built-in Testing of Coherent Optical Receivers

    CERN Document Server

    Mahmutoglu, A Gokcen; Demir, Alper


    We propose discrete-time polarization mode dispersion (PMD) models that are compatible with the emerging coherent receiver techniques, and statistical sampling schemes for the model parameters. These models use multiple-input multiple-output (MIMO) finite impulse response (FIR) filters that are lossless and therefore lend themselves as perfect candidates for emulation of fiber channels suffering from PMD without polarization dependent loss (PDL). The concatenated composition of these filters resembles the continuous time lumped model of PMD channels and offers a flexible emulator and compensator structure in terms of computational complexity which constitutes the main bottleneck for real-time DSP applications.

  16. Internal Defect Measurement of Scattering Media by Optical Coherence Microscopy

    Institute of Scientific and Technical Information of China (English)

    ZHU Yong-kai; ZHAO Hong; WANG Zhao; WANG Jun-li


    Optical coherence microscopy is applied to measure scattering media's internal defect, which based on low coherence interferometry and confocal microscopy. Optical coherence microscopy is more effective in the rejection of out of focus and multiple scattered photons originating further away of the focal plane. With the three-dimension scanning, the internal defect is detected by measuring the thickness of different points on the sample. The axial resolution is 6 μm and lateral resolution is 1.2 μm. This method is possessed of the advantages over the other measurement method of scattering media, such as non-destruction and highresolution.

  17. Coherent Optical Transceiver using Circular Polarization-Based Balanced Mixing Project (United States)

    National Aeronautics and Space Administration — Boulder Nonlinear Systems (BNS) proposes to use its electro-optic component and subsystem expertise to transition a patented heterodyne detection scheme previously...

  18. Coherent analysis of quantum optical sideband modes

    CERN Document Server

    Huntington, E H; Robilliard, C; Ralph, T C


    We demonstrate a device that allows for the coherent analysis of a pair of optical frequency sidebands in an arbitrary basis. We show that our device is quantum noise limited and hence applications for this scheme may be found in discrete and continuous variable optical quantum information experiments.

  19. Coherence-Multiplexed Optical RF Feeder Networks

    NARCIS (Netherlands)

    Meijerink, Arjan; Taniman, Robert O.; Etten, van Wim


    An optical RF feeding system for wireless access is proposed, in which the radio access points are distinguished by means of coherence multiplexing (CM). CM is a rather unknown and potentially inexpensive optical code division multiple access technique, which is particularly suitable for relatively

  20. Patch-based denoising method using low-rank technique and targeted database for optical coherence tomography image. (United States)

    Liu, Xiaoming; Yang, Zhou; Wang, Jia; Liu, Jun; Zhang, Kai; Hu, Wei


    Image denoising is a crucial step before performing segmentation or feature extraction on an image, which affects the final result in image processing. In recent years, utilizing the self-similarity characteristics of the images, many patch-based image denoising methods have been proposed, but most of them, named the internal denoising methods, utilized the noisy image only where the performances are constrained by the limited information they used. We proposed a patch-based method, which uses a low-rank technique and targeted database, to denoise the optical coherence tomography (OCT) image. When selecting the similar patches for the noisy patch, our method combined internal and external denoising, utilizing the other images relevant to the noisy image, in which our targeted database is made up of these two kinds of images and is an improvement compared with the previous methods. Next, we leverage the low-rank technique to denoise the group matrix consisting of the noisy patch and the corresponding similar patches, for the fact that a clean image can be seen as a low-rank matrix and rank of the noisy image is much larger than the clean image. After the first-step denoising is accomplished, we take advantage of Gabor transform, which considered the layer characteristic of the OCT retinal images, to construct a noisy image before the second step. Experimental results demonstrate that our method compares favorably with the existing state-of-the-art methods.

  1. Phase-sensitive optical coherence tomography-based vibrometry using a highly phase-stable akinetic swept laser source

    Energy Technology Data Exchange (ETDEWEB)

    Applegate, Brian E.; Park, Jesung; Carbajal, Esteban [Department of Biomedical Engineering, Texas A& M University, College Station, Texas (United States); Oghalai, John S. [Department of Otolaryngology - Head and Neck Surgery, Stanford University, Stanford, California (United States)


    Phase-sensitive Optical Coherence Tomography (PhOCT) is an emerging tool for in vivo investigation of the vibratory function of the intact middle and inner ear. PhOCT is able to resolve micron scale tissue morphology in three dimensions as well as measure picometer scale motion at each spatial position. Most PhOCT systems to date have relied upon the phase stability offered by spectrometer detection. On the other hand swept laser source based PhOCT offers a number of advantages including balanced detection, long imaging depths, and high imaging speeds. Unfortunately the inherent phase instability of traditional swept laser sources has necessitated complex user developed hardware/software solutions to restore phase sensitivity. Here we present recent results using a prototype swept laser that overcomes these issues. The akinetic swept laser is electronically tuned and precisely controls sweeps without any mechanical movement, which results in high phase stability. We have developed an optical fiber based PhOCT system around the akinetic laser source that had a 1550 nm center wavelength and a sweep rate of 140 kHz. The stability of the system was measured to be 4.4 pm with a calibrated reflector, thus demonstrating near shot noise limited performance. Using this PhOCT system, we have acquired structural and vibratory measurements of the middle ear in a mouse model, post mortem. The quality of the results suggest that the akinetic laser source is a superior laser source for PhOCT with many advantages that greatly reduces the required complexity of the imaging system.

  2. Optical Coherence Tomography in a Needle Format (United States)

    Lorenser, Dirk; McLaughlin, Robert A.; Sampson, David D.

    In this chapter, we review the technology and applications of needle probes for optical coherence tomography (OCT). Needle probes are miniaturized fiber-optic probes that can be mounted inside hypodermic needles, allowing them to be inserted deep into the body during OCT imaging. This overcomes the very limited imaging depth of OCT of only 2-3 mm in biological tissue, enabling access to deep-tissue locations that are beyond the reach of free-space optical scan heads or catheters. This chapter provides an in-depth review of the current state-of-the art in needle probe technology, including optical design and fabrication, scan mechanisms (including three-dimensional scanning), and integration into OCT systems. It also provides an overview of emerging applications of this fascinating new imaging tool in areas such as cancer diagnosis, pulmonary imaging, imaging of the eye and imaging of the brain. Finally, two case studies are presented, illustrating needle-based OCT imaging in breast cancer and lungs.

  3. Advanced modelling of optical coherence tomography systems

    DEFF Research Database (Denmark)

    Andersen, Peter E.; Thrane, L.; Yura, H.T.;


    Analytical and numerical models for describing and understanding the light propagation in samples imaged by optical coherence tomography (OCT) systems are presented. An analytical model for calculating the OCT signal based on the extended Huygens–Fresnel principle valid both for the single...... and multiple scattering regimes is reviewed. An advanced Monte Carlo model for calculating the OCT signal is also reviewed, and the validity of this model is shown through a mathematical proof based on the extended Huygens–Fresnel principle. Moreover, for the first time the model is verified experimentally....... From the analytical model, an algorithm for enhancing OCT images is developed; the so-called true-reflection algorithm in which the OCT signal may be corrected for the attenuation caused by scattering. For the first time, the algorithm is demonstrated by using the Monte Carlo model as a numerical...

  4. Blood flowing state analysis in outflow tract of chick embryonic heart based on spectral domain optical coherence tomography (United States)

    Zhao, Yuqian; Suo, Yanyan; Liang, Chengbo; Ma, Zhenhe


    The cardiac development is a complicated process affected by genetic and environmental factors. Wall shear stress (WSS) and periodic stress (WPS) are the components which have been proved to influence the morphogenesis during early stages of cardiac development. The vessel wall will be deformed by the blood pressure and produce natural elastic force acting on the blood. Because blood flowing in different flow state and show different characteristics of fluid, which influence the calculation of WSS and WPS directly, it is necessary to study the blood flow state. In this paper, we introduce a method to quantify the blood flowing state of early stage chick embryonic heart based on high speed spectral domain optical coherence tomography (SDOCT).4D (x,y,z,t) scan was performed on the outflow tract (OFT) of HH18 (~3 days of incubation) chick embryonic heart. By processing the structural image, the geometric parameters were obtained. Blood flow velocity distribution in the OFT were calculated by Doppler OCT method. Hemodynamic parameters were obtained at different times during the cardiac cycle used biofluid mechanics theory, such as Reynolds number and Womersley number.

  5. Optical coherent control in semiconductors

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Vadim, Lyssenko; Hvam, Jørn Märcher


    of quantum control including the recent applications to semiconductors and nanostructures. We study the influence of inhomogeneous broadening in semiconductors on CC results. Photoluminescence (PL) and the coherent emission in four-wave mixing (FWM) is recorded after resonant excitation with phase...

  6. Optical coherence tomography in late solar retinopathy

    Directory of Open Access Journals (Sweden)

    Janković Aleksandar


    Full Text Available Introduction. Solar retinopathy refers to retinal injury induced by direct or indirect solar viewing. Case report. We presented a patient who had observed partial solar eclipse 51 year before. He had bilaterally decreased vision and scar of the macular region at the time of presentation. The basic diagnostic tool applied in the presented patient, optical coherence tomography, showed hyporeflexivity of the outer retina in the segment of retinal pigment epithelialphotoreceptors complex with atrophy and thinning of the foveolar region. Conclusion. Optical coherence tomography is a powerful, non-invasive diagnostic tool which can ease the diagnosis and estimate the level and nature of the macular region damage.

  7. Simultaneous measurement of group refractive index and thickness of optical samples using optical coherence tomography. (United States)

    Cheng, Hsu-Chih; Liu, Yi-Cheng


    Optical coherence tomography (OCT), based on a Michelson interferometer and utilizing low coherence light as the optical source, is a novel technique for the noninvasive imaging of optical scattering media. A simple OCT scheme based on a 3 x 3 fiber coupler is presented for the simultaneous measurement of the refractive index and thickness of optical samples. The proposed system enables the refractive index and thickness to be determined without any prior knowledge of the sample parameters and is characterized by a simple and compact configuration, a straightforward measurement procedure, and a low cost. The feasibility of the proposed approach is demonstrated experimentally using BK7 and B270 optical glass samples.

  8. Simultaneous measurement of group refractive index and thickness of optical samples using optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Hsu-Chih; Liu, Yi-Cheng


    Optical coherence tomography (OCT), based on a Michelson interferometer and utilizing low coherence light as the optical source, is a novel technique for the noninvasive imaging of optical scattering media. A simple OCT scheme based on a 3x3 fiber coupler is presented for the simultaneous measurement of the refractive index and thickness of optical samples. The proposed system enables the refractive index and thickness to be determined without any prior knowledge of the sample parameters and is characterized by a simple and compact configuration, a straightforward measurement procedure, and a low cost. The feasibility of the proposed approach is demonstrated experimentally using BK7 and B270 optical glass samples.

  9. Image Distortion of Optical Coherence Tomography

    Institute of Scientific and Technical Information of China (English)

    安源; 姚建铨


    A kind of image distortion in Optical Coherence Tomography (OCT) resulted from average refractive index changes between structures of bio-tissue is discussed for the first time.Analysis is given on following situations:1) Exact refraction index changes between microstructures;2)The gradient of average refractive index change between different tissue layers is parallel to the probe beam;3) The gradient of average refractive index change is vertical to the probe beam.The results show that the image distortion of situation 1) is usually negligible;in situation 2) there is a spread or shrink effect without relative location error; however,in situation 3) there is a significant image error inducing relative location displacement between different structures.Preliminary design to eliminate the distortion is presented,the method of which mainly based on the image classification and pixel array re-arrangement.

  10. Quantitative contrast-enhanced optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Winetraub, Yonatan; SoRelle, Elliott D. [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Biophysics Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Liba, Orly [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Electrical Engineering, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Zerda, Adam de la [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Biophysics Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Electrical Engineering, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States)


    We have developed a model to accurately quantify the signals produced by exogenous scattering agents used for contrast-enhanced Optical Coherence Tomography (OCT). This model predicts distinct concentration-dependent signal trends that arise from the underlying physics of OCT detection. Accordingly, we show that real scattering particles can be described as simplified ideal scatterers with modified scattering intensity and concentration. The relation between OCT signal and particle concentration is approximately linear at concentrations lower than 0.8 particle per imaging voxel. However, at higher concentrations, interference effects cause signal to increase with a square root dependence on the number of particles within a voxel. Finally, high particle concentrations cause enough light attenuation to saturate the detected signal. Predictions were validated by comparison with measured OCT signals from gold nanorods (GNRs) prepared in water at concentrations ranging over five orders of magnitude (50 fM to 5 nM). In addition, we validated that our model accurately predicts the signal responses of GNRs in highly heterogeneous scattering environments including whole blood and living animals. By enabling particle quantification, this work provides a valuable tool for current and future contrast-enhanced in vivo OCT studies. More generally, the model described herein may inform the interpretation of detected signals in modalities that rely on coherence-based detection or are susceptible to interference effects.

  11. Accuracy of optical navigation systems for automatic head surgery: optical tracking versus optical coherence tomography (United States)

    Díaz Díaz, Jesús; Riva, Mauro H.; Majdani, Omid; Ortmaier, Tobias


    The choice of a navigation system highly depends on the medical intervention and its accuracy demands. The most commonly used systems for image guided surgery (IGS) are based on optical and magnetic tracking systems. This paper compares two optical systems in terms of accuracy: state of the art triangulation-based optical tracking (OT) and optical coherence tomography (OCT). We use an experimental setup with a combined OCT and cutting laser, and an external OT. We simulate a robotic assisted surgical intervention, including planning, navigation, and processing, and compare the accuracies reached at a specific target with each navigation system.

  12. Adaptive 4~64 QAM real-time coherent optical transmission over 320 km with FPGA-based transmitter and receiver. (United States)

    Yoshida, Masato; Hirooka, Toshihiko; Kasai, Keisuke; Nakazawa, Masataka


    We demonstrate the first real-time adaptive optical coherent QAM transmission with variable multiplicities (4-, 16- and 64-QAM) using an FPGA-based transmitter and receiver. Rate-variable transmission (20~60 Gbit/s) was successfully achieved with a polarization multiplexing scheme at 5 Gsymbol/s over 320 km, where the OSNR margins were increased by 9 and 17 dB, respectively, by changing the modulation level from 64 to 16 and 4.

  13. Machine learning based detection of age-related macular degeneration (AMD) and diabetic macular edema (DME) from optical coherence tomography (OCT) images


    Wang, Yu; Zhang, Yaonan; Yao, Zhaomin; Zhao, Ruixue; Zhou, Fengfeng


    Non-lethal macular diseases greatly impact patients’ life quality, and will cause vision loss at the late stages. Visual inspection of the optical coherence tomography (OCT) images by the experienced clinicians is the main diagnosis technique. We proposed a computer-aided diagnosis (CAD) model to discriminate age-related macular degeneration (AMD), diabetic macular edema (DME) and healthy macula. The linear configuration pattern (LCP) based features of the OCT images were screened by the Corr...

  14. Demonstrational Optics Part 2: Coherent and Statistical Optics

    CERN Document Server

    Marchenko, Oleg; Windholz, Laurentius


    Demonstrational Optics presents a new didactical approach to the study of optics. Emphasizing the importance of elaborate new experimental demonstrations, pictorial illustrations, computer simulations and models of optical phenomena in order to ensure a deeper understanding of wave and geometric optics. It includes problems focused on the pragmatic needs of students, secondary school teachers, university professors and optical engineers. Part 2, Coherent and Statistical Optics, contains chapters on interference, diffraction, Fourier optics, light quanta, thermal radiation (Shot noise and Gaussian light), Correlation of light fields and Correlation of light intensities. A substantial part of this volume is devoted to thermal radiation and its properties, especially with partial coherence. A detailed treatment of the photo-effect with respect to statistical properties leads to the basics of statistical optics. To illustrate the phenomena covered by this volume, a large number of demonstration experiments are de...

  15. Optical coherence tomography: Technique and applications

    DEFF Research Database (Denmark)

    Thomsen, Jakob Borup; Sander, Birgit; Mogensen, Mette;


    Optical coherence tomography (OCT) is a noninvasive optical imaging modality providing real-time video rate images in two and three dimensions of biological tissues with micrometer resolution. OCT fills the gap between ultrasound and confocal microscopy, since it has a higher resolution than ultr...... of retinal diseases. The potential of OCT in many other applications is currently being explored, such as in developmental biology, skin cancer diagnostics, vulnerable plaque detection in cardiology, esophageal diagnostics and a number of other applications within oncology....

  16. Noise-immune complex correlation for vasculature imaging based on standard and Jones-matrix optical coherence tomography (United States)

    Makita, Shuichi; Kurokawa, Kazuhiro; Hong, Young-Joo; Li, En; Miura, Masahiro; Yasuno, Yoshiaki


    A new optical coherence angiography (OCA) method, called correlation mapping OCA (cmOCA), is presented by using the SNR-corrected complex correlation. An SNR-correction theory for the complex correlation calculation is presented. The method also integrates a motion-artifact-removal method for the sample motion induced decorrelation artifact. The theory is further extended to compute more reliable correlation by using multi- channel OCT systems, such as Jones-matrix OCT. The high contrast vasculature imaging of in vivo human posterior eye has been obtained. Composite imaging of cmOCA and degree of polarization uniformity indicates abnormalities of vasculature and pigmented tissues simultaneously.

  17. Optical Coherence Tomography for Material Characterization

    NARCIS (Netherlands)

    Liu, P.


    Optical coherence tomography (OCT) is a non-invasive, contactless and high resolution imaging method, which allows the reconstruction of two or three dimensional depth-resolved images in turbid media. In the past 20 years, OCT has been extensively developed in the field of biomedical diagnostics, wh

  18. Functional optical coherence tomography of pigmented lesions

    NARCIS (Netherlands)

    Wessels, R.; Bruin, de D.M.; Relyveld, G.N.; Faber, D.J.; Vincent, A.D.; Sanders, J.; Leeuwen, van T.G.; Ruers, T.J.M.


    Background Cutaneous melanomas are diagnosed worldwide in 231 130 patients per year. The sensitivity and specificity of melanoma diagnosis expresses the need for an additional diagnostic method. Optical coherence tomography (OCT) has shown that it allows morphological (qualitative) description of im

  19. Gabor fusion master slave optical coherence tomography

    DEFF Research Database (Denmark)

    Cernat, Ramona; Bradu, Adrian; Israelsen, Niels Møller


    This paper describes the application of the Gabor filtering protocol to a Master/Slave (MS) swept source optical coherence tomography (SS)-OCT system at 1300 nm. The MS-OCT system delivers information from selected depths, a property that allows operation similar to that of a time domain OCT syst...

  20. High Dynamic Range Imaging Concept-Based Signal Enhancement Method Reduced the Optical Coherence Tomography Measurement Variability (United States)

    Ishikawa, Hiroshi; Chen, Chieh-Li; Wollstein, Gadi; Grimm, Jonathan L.; Ling, Yun; Bilonick, Richard A.; Sigal, Ian A.; Kagemann, Larry; Schuman, Joel S.


    Purpose. To develop and test a novel signal enhancement method for optical coherence tomography (OCT) images based on the high dynamic range (HDR) imaging concept. Methods. Three virtual channels, which represent low, medium, and high signal components, were produced for each OCT signal dataset. The dynamic range of each signal component was normalized to the full gray scale range. Finally, the three components were recombined into one image using various weights. Fourteen eyes of 14 healthy volunteers were scanned multiple times using time-domain (TD)-OCT before and while preventing blinking in order to produce a wide variety of signal strength (SS) images on the same eye scanned on the same day. For each eye, a pair of scans with the highest and lowest SS with successful retinal nerve fiber layer (RNFL) segmentation was selected to test the signal enhancement effect. In addition, spectral-domain (SD)-OCT images with poor signal qualities were also processed. Results. Mean SS of good and poor quality scans were 9.0 ± 1.1 and 4.4 ± 0.9, respectively. TD-OCT RNFL thickness showed significant differences between good and poor quality scans on the same eye (mean difference 11.9 ± 6.0 μm, P < 0.0001, paired t-test), while there was no significant difference after signal enhancement (1.7 ± 6.2 μm, P = 0.33). However, HDR had weaker RNFL compensation effect on images with SS less than or equal to 4, while it maintained good compensation effect on images with SS greater than 4. Successful signal enhancement was also confirmed subjectively on SD-OCT images. Conclusion. The HDR imaging successfully restored OCT signal and image quality and reduced RNFL thickness differences due to variable signal level to the level within the expected measurement variability. This technique can be applied to both TD- and SD-OCT images. PMID:23299477

  1. Enhancement of the low-frequency response of a reflective semiconductor optical amplifier slow light-based microwave phase shifter by forced coherent population oscillations (United States)

    Meehan, Aidan; Connelly, Michael J.


    The enhancement of the low frequency gain response of a microwave phase shifter based on slow light in a bulk reflective semiconductor optical amplifier (RSOA), by using forced coherent population oscillations (FCPO), is experimentally demonstrated. FCPO is achieved by simultaneously modulating the input optical power and bias current. The beat signal gain improvement ranges from 45 to 0 dB over a frequency range of 0.5 to 2.5 GHz, thereby improving the noise performance of the phase shifter. Tunable phase shifts of up to 40º are possible over this frequency range.

  2. Analysis of optical amplifier noise in coherent optical communication systems with optical image rejection receivers

    DEFF Research Database (Denmark)

    Jørgensen, Bo Foged; Mikkelsen, Benny; Mahon, Cathal J.


    performance. Two types of optical image rejection receivers are investigated: a novel, all-optical configuration and the conventional, microwave-based configuration. The analysis shows that local oscillator-spontaneous emission beat noise (LO-SP), signal-spontaneous emission beat noise (S-SP), and spontaneous......A detailed theoretical analysis of optical amplifier noise in coherent optical communication systems with heterodyne receivers is presented. The analysis quantifies in particular how optical image rejection receiver configurations reduce the influence of optical amplifier noise on system......-spontaneous beat noise (SP-SP) can all be reduced by 3 dB, thereby doubling the dynamic range of the optical amplifier. A 2.5-dB improvement in dynamic range has been demonstrated experimentally with the all-optical image rejection configuration. The implications of the increased dynamic range thus obtained...

  3. Optical coherence tomography used for internal biometrics (United States)

    Chang, Shoude; Sherif, Sherif; Mao, Youxin; Flueraru, Costel


    Traditional biometric technologies used for security and person identification essentially deal with fingerprints, hand geometry and face images. However, because all these technologies use external features of human body, they can be easily fooled and tampered with by distorting, modifying or counterfeiting these features. Nowadays, internal biometrics which detects the internal ID features of an object is becoming increasingly important. Being capable of exploring under-skin structure, optical coherence tomography (OCT) system can be used as a powerful tool for internal biometrics. We have applied fiber-optic and full-field OCT systems to detect the multiple-layer 2D images and 3D profile of the fingerprints, which eventually result in a higher discrimination than the traditional 2D recognition methods. More importantly, the OCT based fingerprint recognition has the ability to easily distinguish artificial fingerprint dummies by analyzing the extracted layered surfaces. Experiments show that our OCT systems successfully detected the dummy, which was made of plasticene and was used to bypass the commercially available fingerprint scanning system with a false accept rate (FAR) of 100%.

  4. Homodyne en face optical coherence tomography


    Yaqoob, Zahid; Fingler, Jeff; Heng, Xin; Yang, Changhuei


    We demonstrate, for what we believe to be the first time, the use of a 3×3 fiber-optic coupler to realize a homodyne optical coherence tomography (OCT) system for en face imaging of highly scattering tissues and turbid media. The homodyne OCT setup exploits the inherent phase shifts between different output ports of a 3×3 fiber-optic coupler to extract amplitude information of a sample. Our homodyne en face OCT system features a measured resolution of 14 μm axially and 9.4 μm laterally with a...

  5. Machine learning based detection of age-related macular degeneration (AMD) and diabetic macular edema (DME) from optical coherence tomography (OCT) images. (United States)

    Wang, Yu; Zhang, Yaonan; Yao, Zhaomin; Zhao, Ruixue; Zhou, Fengfeng


    Non-lethal macular diseases greatly impact patients' life quality, and will cause vision loss at the late stages. Visual inspection of the optical coherence tomography (OCT) images by the experienced clinicians is the main diagnosis technique. We proposed a computer-aided diagnosis (CAD) model to discriminate age-related macular degeneration (AMD), diabetic macular edema (DME) and healthy macula. The linear configuration pattern (LCP) based features of the OCT images were screened by the Correlation-based Feature Subset (CFS) selection algorithm. And the best model based on the sequential minimal optimization (SMO) algorithm achieved 99.3% in the overall accuracy for the three classes of samples.

  6. Lasers and holography an introduction to coherent optics

    CERN Document Server

    KOCK, Winston


    Science Study Series No. 39: Lasers and Holography: An Introduction to Coherent Optics focuses on the processes, methodologies, and techniques involved in optics, including wave diffraction and patterns, zone plates, holograms, and diffraction. The publication first ponders on holograms as wave patterns, coherence, and lasers. Topics include reflectors and resonators, natural line width, semiconductor lasers, reflectors and spatial coherence, energy conservation with reflectors, frequency coherence and stability, coherent waves from small sources, photographic grating, and properties o

  7. Coherent control of optical activity and optical anisotropy of thin metamaterials

    CERN Document Server

    Mousavi, Seyedmohammad A; Shi, Jinhui; Zheludev, Nikolay I


    The future fibre optic communications network will rely on photons as carriers of information, which may be stored in intensity, polarization or phase of light. However, processing of such optical information usually relies on electronics. Aiming to avoid the conversion between optical and electronic signals, modulation of light with light based on optical nonlinearity has become a major research field, but real integrated all-optical systems face thermal management and energy challenges. On the other hand, it has recently been demonstrated that the interaction of two coherent light beams on a thin, lossy, linear material can lead to large and ultrafast intensity modulation at arbitrarily low power resulting from coherent absorption. Here we demonstrate that birefringence and optical activity (linear and circular birefringence and dichroism) of functional materials can be coherently controlled by placing a thin material slab into a standing wave formed by the signal and control waves. Efficient control of the...

  8. [Applications of optical coherence tomography (OCT) in neuro-ophthalmology]. (United States)

    Kernstock, C; Friebe, K; Tonagel, F


    Optical coherence tomography (OCT) has revolutionised ophthalmology. Due to modern instruments with extremely high resolution there are more and more applications also in neuro-ophthalmological disorders. This review gives an overview on typical changes in OCT for the following diseases: autosomal dominant optic atrophy, Leber hereditary optic neuropathy, toxic, traumatic and compressive optic neuropathy, optic nerve drusen, anterior ischaemic optic neuropathy, optic disc pit, papilledema, optic neuritis (isolated or associated with multiple sclerosis or neuromyelitis optica), neurodegenerative diseases and hereditary retinal diseases. A diagnosis exclusively based on an OCT examination is not always possible, but in several diseases there are pathognomonic changes that directly lead to the correct diagnosis. Particularly with the often complex settings in neuro-ophtalmology the OCT should be seen as a supplementary modality and not as a replacement for other techniques.

  9. Classifying murine glomerulonephritis using optical coherence tomography and optical coherence elastography. (United States)

    Liu, Chih-Hao; Du, Yong; Singh, Manmohan; Wu, Chen; Han, Zhaolong; Li, Jiasong; Chang, Anthony; Mohan, Chandra; Larin, Kirill V


    Acute glomerulonephritis caused by antiglomerular basement membrane marked by high mortality. The primary reason for this is delayed diagnosis via blood examination, urine analysis, tissue biopsy, or ultrasound and X-ray computed tomography imaging. Blood, urine, and tissue-based diagnoses can be time consuming, while ultrasound and CT imaging have relatively low spatial resolution, with reduced sensitivity. Optical coherence tomography is a noninvasive and high-resolution imaging technique that provides superior spatial resolution (micrometer scale) as compared to ultrasound and CT. Changes in tissue properties can be detected based on the optical metrics analyzed from the OCT signals, such as optical attenuation and speckle variance. Furthermore, OCT does not rely on ionizing radiation as with CT imaging. In addition to structural changes, the elasticity of the kidney can significantly change due to nephritis. In this work, OCT has been utilized to quantify the difference in tissue properties between healthy and nephritic murine kidneys. Although OCT imaging could identify the diseased tissue, its classification accuracy is clinically inadequate. By combining optical metrics with elasticity, the classification accuracy improves from 76% to 95%. These results show that OCT combined with OCE can be a powerful tool for identifying and classifying nephritis. Therefore, the OCT/OCE method could potentially be used as a minimally invasive tool for longitudinal studies during the progression and therapy of glomerulonephritis as well as complement and, perhaps, substitute highly invasive tissue biopsies. Elastic-wave propagation in mouse healthy and nephritic kidneys.

  10. Analog signal processing for optical coherence imaging systems (United States)

    Xu, Wei

    Optical coherence tomography (OCT) and optical coherence microscopy (OCM) are non-invasive optical coherence imaging techniques, which enable micron-scale resolution, depth resolved imaging capability. Both OCT and OCM are based on Michelson interferometer theory. They are widely used in ophthalmology, gastroenterology and dermatology, because of their high resolution, safety and low cost. OCT creates cross sectional images whereas OCM obtains en face images. In this dissertation, the design and development of three increasingly complicated analog signal processing (ASP) solutions for optical coherence imaging are presented. The first ASP solution was implemented for a time domain OCT system with a Rapid Scanning Optical Delay line (RSOD)-based optical signal modulation and logarithmic amplifier (Log amp) based demodulation. This OCT system can acquire up to 1600 A-scans per second. The measured dynamic range is 106dB at 200A-scan per second. This OCT signal processing electronics includes an off-the-shelf filter box with a Log amp circuit implemented on a PCB board. The second ASP solution was developed for an OCM system with synchronized modulation and demodulation and compensation for interferometer phase drift. This OCM acquired micron-scale resolution, high dynamic range images at acquisition speeds up to 45,000 pixels/second. This OCM ASP solution is fully custom designed on a perforated circuit board. The third ASP solution was implemented on a single 2.2 mm x 2.2 mm complementary metal oxide semiconductor (CMOS) chip. This design is expandable to a multiple channel OCT system. A single on-chip CMOS photodetector and ASP channel was used for coherent demodulation in a time domain OCT system. Cross-sectional images were acquired with a dynamic range of 76dB (limited by photodetector responsivity). When incorporated with a bump-bonded InGaAs photodiode with higher responsivity, the expected dynamic range is close to 100dB.

  11. Optical Coherence Tomography Velocimetry with Complex Fluids (United States)

    Malm, A.; Waigh, T. A.; Jaradat, S.; Tomlin, R.


    We present recent results obtained with an Optical Coherence Tomography Velocimetry technique. An optical interferometer measures the velocity of a sheared fluid at specific depths of the sample using the coherence length of the light source. The technique allows the dynamics of 3 pico liter volumes to be probed inside opaque complex fluids. In a study of opaque starch suspensions, classical bulk rheology experiments show non-linear shear thickening, whereas observations of the velocity profiles as a function of distance across the gap show Newtonian behavior. The ability of the technique to measure velocity fluctuations is also discussed for the case of polyacrylamide samples which were observed to display shear banding behavior. A relationship between the viscoelasticity of the sample and the size of the apparent fluctuations is observed.

  12. Normative data of outer photoreceptor layer thickness obtained by software image enhancing based on Stratus optical coherence tomography images

    DEFF Research Database (Denmark)

    Christensen, U.C.; Krøyer, K.; Thomadsen, Jakob


    Aim: To present normative data of outer photoreceptor layer thickness obtained by a new semiautomatic image analysis algorithm operating on contrast-enhanced optical coherence tomography (OCT) images. Methods: Eight Stratus OCT3 scans from identical retinal locations from 25 normal eyes were...... registered and combined to form a contrast-enhanced average image. Utilising the vertical intensity gradients of the enhanced OCT images to demarcate retinal layers, thickness measurements of the outer photoreceptor- and retinal pigment epithelium layer (RPE-OScomplex) were obtained. Additionally...... in the superior macula 0.5-3 mm of the centre was significantly increased as compared with the corresponding inferior retina. In healthy subjects, the I-ratio-ONL was 1.06. Conclusions: Contrast-enhanced OCT images enable quantification of outer photoreceptor layer thickness, and normative values may help...

  13. Motion contrast using optical coherence tomography (United States)

    Fingler, Jeffrey Paul

    Diagnosis of ophthalmic diseases like age-related macular degeneration is very important for treatment of the disease as well as the development of future treatments. Optical coherence tomography (OCT) is an optical interference technique which can measure the three-dimensional structural information of the reflecting layers within a sample. In retinal imaging, OCT is used as the primary diagnostic tool for structural abnormalities such as retinal holes and detachments. The contrast within the images of this technique is based upon reflectivity changes from different regions of the retina. This thesis demonstrates the developments of methods used to produce additional contrast to the structural OCT images based on the tiny fluctuations of motion experienced by the mobile scatterers within a sample. Motion contrast was observed for motions smaller than 50 nm in images of a variety of samples. Initial contrast method demonstrations used Brownian motion differences to separate regions of a mobile Intralipid solution from a static agarose gel, chosen in concentration to minimize reflectivity contrast. Zebrafish embryos in the range of 3-4 days post fertilization were imaged using several motion contrast methods to determine the capabilities of identifying regions of vascular flow. Vasculature identification was demonstrated in zebrafish for blood vessels of all orientations as small as 10 microns in diameter. Mouse retinal imaging utilized the same motion contrast methods to determine the contrast capabilities for motions associated with vasculature within the retina. Improved contrast imaging techniques demonstrated comparable images to fluorescein angiography, the gold standard of retinal vascular imaging. Future studies can improve the demonstrated contrast analysis techniques and apply them towards human retinal motion contrast imaging for ophthalmic diagnostic purposes.

  14. Interconnection of polarization properties and coherence of optical fields. (United States)

    Zenkova, Claudia Yu


    Theoretical and experimental approaches to diagnosing internal spin and orbital optical flows and the corresponding optical forces caused by these flows are offered. These approaches are based on the investigation of the motion of the particles tested in the formed optical field. The dependence of the above-mentioned forces upon the size and optical properties of the particles is demonstrated. The possibility of using kinematic values defining the motion dynamics of particles of the Rayleigh light scattering mechanism to make a quantitative assessment of the degree of coherence of mutually orthogonal waves that are linearly polarized in the incidence plane is demonstrated. The feasibility of using the above mentioned approach, its shortcomings, and its advantages over the interfering method for estimating the degree of coherence are analyzed.

  15. Coherent conversion between optical and microwave photons in Rydberg gases

    CERN Document Server

    Kiffner, Martin; Kaczmarek, Krzysztof T; Jaksch, Dieter; Nunn, Joshua


    Quantum information encoded in optical photons can be transmitted over long distances with very high information density, and suffers from negligible thermal noise at room temperature. On the other hand, microwave photons at cryogenic temperatures can be confined in high quality resonators and strongly coupled to solid-state qubits, providing a quantum bus to connect qubits and a route to deterministic photonic non-linearities. The coherent interconversion of microwave and optical photons has therefore recently emerged as a highly desirable capability that would enable freely-scalable networks of optically-linked qubits, or large-scale photonic information processing with multi-photon interactions mediated by microwaves. Here, we propose a route to efficient and coherent microwave-optical conversion based on frequency mixing in Rydberg atoms. The interaction requires no microfabricated components or cavities, and is tunable, broadband, and both spatially and spectrally multimode.

  16. Adaptive optics optical coherence tomography at 1 MHz. (United States)

    Kocaoglu, Omer P; Turner, Timothy L; Liu, Zhuolin; Miller, Donald T


    Image acquisition speed of optical coherence tomography (OCT) remains a fundamental barrier that limits its scientific and clinical utility. Here we demonstrate a novel multi-camera adaptive optics (AO-)OCT system for ophthalmologic use that operates at 1 million A-lines/s at a wavelength of 790 nm with 5.3 μm axial resolution in retinal tissue. Central to the spectral-domain design is a novel detection channel based on four high-speed spectrometers that receive light sequentially from a 1 × 4 optical switch assembly. Absence of moving parts enables ultra-fast (50ns) and precise switching with low insertion loss (-0.18 dB per channel). This manner of control makes use of all available light in the detection channel and avoids camera dead-time, both critical for imaging at high speeds. Additional benefit in signal-to-noise accrues from the larger numerical aperture afforded by the use of AO and yields retinal images of comparable dynamic range to that of clinical OCT. We validated system performance by a series of experiments that included imaging in both model and human eyes. We demonstrated the performance of our MHz AO-OCT system to capture detailed images of individual retinal nerve fiber bundles and cone photoreceptors. This is the fastest ophthalmic OCT system we know of in the 700 to 915 nm spectral band.

  17. Anti-Stokes effect CCD camera and SLD based optical coherence tomography for full-field imaging in the 1550nm region (United States)

    Kredzinski, Lukasz; Connelly, Michael J.


    Full-field Optical coherence tomography is an en-face interferometric imaging technology capable of carrying out high resolution cross-sectional imaging of the internal microstructure of an examined specimen in a non-invasive manner. The presented system is based on competitively priced optical components available at the main optical communications band located in the 1550 nm region. It consists of a superluminescent diode and an anti-stokes imaging device. The single mode fibre coupled SLD was connected to a multi-mode fibre inserted into a mode scrambler to obtain spatially incoherent illumination, suitable for OCT wide-field modality in terms of crosstalk suppression and image enhancement. This relatively inexpensive system with moderate resolution of approximately 24um x 12um (axial x lateral) was constructed to perform a 3D cross sectional imaging of a human tooth. To our knowledge this is the first 1550 nm full-field OCT system reported.

  18. MEMS-based handheld scanning probe with pre-shaped input signals for distortion-free images in Gabor-domain optical coherence microscopy. (United States)

    Cogliati, Andrea; Canavesi, Cristina; Hayes, Adam; Tankam, Patrice; Duma, Virgil-Florin; Santhanam, Anand; Thompson, Kevin P; Rolland, Jannick P


    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.

  19. Optical coherent tomography in diagnoses of peripheral retinal degenarations

    Directory of Open Access Journals (Sweden)

    O. G. Pozdeyeva


    Full Text Available Purpose: Studying the capabilities of optical coherence tomography (RTVue-100, OPTOVUE, USA in evaluation of peripheral retinal degenerations, vitreoretinal adhesions, adjacent vitreous body as well as measurement of morphometric data.Methods: The study included 189 patients (239 eyes with peripheral retinal degeneration. 77 men and 112 women aged 18 to 84 underwent an ophthalmologic examination since November 2012 until October 2013. The peripheral retina was visualized with the help of optical coherence tomography («RTVue-100,» USA. The fundography was carried out using a Nikon NF505‑AF (Japan fundus camera. All patients were examined with a Goldmann lens.Results: Optical coherence tomography was used to evaluate different kinds of peripheral retinal degenerations, such as lattice and snail track degeneration, isolated retinal tears, cystoid retinal degeneration, pathological hyperpigmentation, retinoschisis and cobblestone degeneration. The following morphometric data were studied: dimensions of the lesion (average length, retinal thickness along the edge of the lesion, retinal thickness at the base of the lesion and the vitreoretinal interface.Conclusion: Optical coherence tomography is a promising in vivo visualization method which is useful in evaluation of peripheral retinal degenerations, vitreoretinal adhesions and tractions. It also provides a comprehensive protocolling system and monitoring. It will enable ophthalmologists to better define laser and surgical treatment indications and evaluate therapy effectiveness.

  20. Optical coherence tomography findings of quinine poisoning

    Directory of Open Access Journals (Sweden)

    John Christoforidis


    Full Text Available John Christoforidis, Robert Ricketts, Theodore Loizos, Susie ChangThe Ohio State University College of Medicine, Columbus, OH, USAPurpose: To report a case of acute quinine poisoning, document acute and chronic macular changes with optical coherence tomography imaging and fluorescein angiography (FA, and to review the literature on ocular toxicity of quinine.Methods: A 32-year-old white female presented to our Emergency Department after ingesting over 7.5 g of quinine. She underwent a complete ophthalmologic examination, fluorescein angiography, Stratus time-domain optical coherence tomography (OCT, and electroretinography at 72 hours and 15 months postingestion. Stratus time-domain and Cirrus spectral-domain OCT, fundus autofluorescence, and FA were obtained at 28 months postingestion.Results: Fluorescein angiography at 72 hours postingestion revealed normal filling times and vasculature. OCT showed marked thickening of the inner retina bilaterally. At 15 and 28 months follow-up, fundus photography and fluorescein angiography demonstrated optic nerve pallor, severely attenuated retinal vessels while OCT showed inner retinal atrophy. Fundus autofluorescence did not reveal any retinal pigmentary abnormalities.Conclusions: Quinine toxicity as seen by OCT reveals increased thickness with inner retinal hyperreflectivity acutely with development of significant retinal atrophy in the long-term. Fundus autofluorescence reveals an intact retinal pigment epithelial layer at 28 months. These findings suggest that quinine poisoning may produce a direct toxic effect on the inner retina in the acute phase resulting in long-term retinal atrophy.Keywords: retinal, optical coherence tomography, quinine toxicity 

  1. Dental diagnostics using optical coherence techniques

    Energy Technology Data Exchange (ETDEWEB)

    Nathel, H. [Lawrence Livermore National Lab., CA (United States); Colston, B. [Univ. of California, San Francisco, CA (United States); Armitage, G. [Univ. of California, Davis, CA (United States)] [and others


    Optical radiation can be used for diagnostic purposes in oral medicine. However, due to the turbid, amorphous, and inhomogeneous nature of dental tissue conventional techniques used to transilluminate materials are not well suited to dental tissues. Optical coherence techniques either in the time- of frequency-domain offer the capabilities of discriminating scattered from unscattered light, thus allowing for imaging through turbid tissue. Currently, using optical time-domain reflectometry we are able to discriminate specular from diffuse reflections occurring at tissue boundaries. We have determined the specular reflectivity of enamel and dentin to be approximately 6.6 x 10{sup -5} and 1.3 x 10{sup -6}, respectively. Implications to periodontal imaging will be discussed.

  2. Cubic meter volume optical coherence tomography (United States)



    Optical coherence tomography (OCT) is a powerful three-dimensional (3D) imaging modality with micrometer-scale axial resolution and up to multi-GigaVoxel/s imaging speed. However, the imaging range of high-speed OCT has been limited. Here, we report 3D OCT over cubic meter volumes using a long coherence length, 1310 nm vertical-cavity surface-emitting laser and silicon photonic integrated circuit dual-quadrature receiver technology combined with enhanced signal processing. We achieved 15 µm depth resolution for tomographic imaging at a 100 kHz axial scan rate over a 1.5 m range. We show 3D macroscopic imaging examples of a human mannequin, bicycle, machine shop gauge blocks, and a human skull/brain model. High-bandwidth, meter-range OCT demonstrates new capabilities that promise to enable a wide range of biomedical, scientific, industrial, and research applications. PMID:28239628

  3. Concept of coherence of learning physical optics (United States)

    Colombo, Elisa M.; Jaen, Mirta; de Cudmani, Leonor C.


    The aim of the actual paper is to enhance achievements of the text 'Optica Fisica Basica: estructurada alrededor del concepto de coherencia luminosa' (in English 'Basic Physical Optics centered in the concept of coherence'). We consider that this book is a very worth tool when one has to learn or to teach some fundamental concepts of physical optics. It is well known that the topics of physical optics present not easy understanding for students. Even more they also present some difficulties for the teachers when they have to introduce them to the class. First, we think that different phenomena like diffraction and polarization could be well understood if the starting point is a deep comprehension of the concept of interference of light and, associated with this, the fundamental and nothing intuitive concept of coherence of the light. In the reference text the authors propose the use of expression 'stable interference pattern of no uniform intensity' instead of 'pattern of interference' and 'average pattern of uniform untested' instead of 'lack of interference' to make reference that light always interfere but just under restrictive conditions it can be got temporal and spatial stability of the pattern. Another idea we want to stand out is that the ability to observe a 'stable interference pattern of no uniform intensity' is associated not only with the coherence of the source but also with the dimensions of the experimental system and with the temporal and spatial characteristics of the detector used - human eye, photographic film, etc. The proposal is well support by quantitative relations. With an alternate model: a train of waves with a finite length of coherence, it is possible to get range of validity of models, to decide when a source could be considered a 'point' or 'monochromatic' or 'remote', an 'infinite' wave or a train of waves, etc. Using this concept it is possible to achieve a better understanding of phenomena like the polarization of light. Here, it

  4. Optical coherence tomography based imaging of dental demineralisation and cavity restoration in 840 nm and 1310 nm wavelength regions (United States)

    Damodaran, Vani; Rao, Suresh Ranga; Vasa, Nilesh J.


    In this paper, a study of in-house built optical coherence tomography (OCT) system with a wavelength of 840 nm for imaging of dental caries, progress in demineralisation and cavity restoration is presented. The caries when imaged with the 840 nm OCT system showed minute demineralisation in the order of 5 μm. The OCT system was also proposed to study the growth of lesion and this was demonstrated by artificially inducing caries with a demineralisation solution of pH 4.8. The progress of carious lesion to a depth of about 50-60 μm after 60 hours of demineralisation was clearly observed with the 840 nm OCT system. The tooth samples were subjected to accelerated demineralisation condition at pH of approximately 2.3 to study the adverse effects and the onset of cavity formation was clearly observed. The restoration of cavity was also studied by employing different restorative materials (filled and unfilled). In the case of restoration without filler material (unfilled), the restoration boundaries were clearly observed. Overall, results were comparable with that of the widely used 1310 nm OCT system. In the case of restoration with filler material, the 1310 nm OCT imaging displayed better imaging capacity due to lower scattering than 840 nm imaging.

  5. Retinal Arteriolar Morphometry Based on Full Width at Half Maximum Analysis of Spectral-Domain Optical Coherence Tomography Images.

    Directory of Open Access Journals (Sweden)

    Yu Hua Tong

    Full Text Available In this study, we develop a microdensitometry method using full width at half maximum (FWHM analysis of the retinal vascular structure in a spectral-domain optical coherence tomography (SD-OCT image and present the application of this method in the morphometry of arteriolar changes during hypertension.Two raters using manual and FWHM methods measured retinal vessel outer and lumen diameters in SD-OCT images. Inter-rater reproducibility was measured using coefficients of variation (CV, intraclass correlation coefficient and a Bland-Altman plot. OCT images from forty-three eyes of 43 hypertensive patients and 40 eyes of 40 controls were analyzed using an FWHM approach; wall thickness, wall cross-sectional area (WCSA and wall to lumen ratio (WLR were subsequently calculated.Mean difference in inter-rater agreement ranged from -2.713 to 2.658 μm when using a manual method, and ranged from -0.008 to 0.131 μm when using a FWHM approach. The inter-rater CVs were significantly less for the FWHM approach versus the manual method (P < 0.05. Compared with controls, the wall thickness, WCSA and WLR of retinal arterioles were increased in the hypertensive patients, particular in diabetic hypertensive patients.The microdensitometry method using a FWHM algorithm markedly improved inter-rater reproducibility of arteriolar morphometric analysis, and SD-OCT may represent a promising noninvasive method for in vivo arteriolar morphometry.

  6. Applications of Doppler optical coherence tomography (United States)

    Xu, Zhiqiang

    A major development in biomedical imaging in the last decade has been optical coherence tomography (OCT). This technique enables microscale resolution, depth resolved imaging of the detailed morphology of transparent and nontransparent biological tissue in a noncontact and quasi-noninvasive way. In the first part of this dissertation, we will describe the development and the performance of our home-made OCT systems working with different wavelength regions based on free-space and optical fiber Michelson interferometers. The second part will focus on Doppler OCT (DOCT), an important extension of OCT, which enables the simultaneous evaluation of the structural information and of the fluid flow distribution at a localized position beneath the sample surface. Much effort has been spent during the past few years in our laboratory aimed at providing more accurate velocity measurements with an extended dynamic range. We also applied our technique in different research areas such as microfluidics and hemodynamics. Investigations on the optical properties of the biological tissues (such as absorption and scattering) corresponding to different center wavelengths, have been performed in our laboratory. We used a 10 femtosecond Ti:sapphire laser centered at about 810 nm associated with a free-space Michelson interferometer. The infrared sources were centered at about 1310 and 1560 nm with all-fiber interferometers. Comparative studies using three different sources for several in vitro biological tissues based on a graphical method illustrated how the optical properties affect the quality of the OCT images in terms of the penetration depth and backscattering intensity. We have shown the advantage of working with 810-nm emission wavelength for good backscattering amplitude and contrast, while sources emitting at 1570 nm give good penetration depth. The 1330-nm sources provide a good compromise between the two. Therefore, the choice of the source will ultimately determine the

  7. MEMS scanning micromirror for optical coherence tomography. (United States)

    Strathman, Matthew; Liu, Yunbo; Keeler, Ethan G; Song, Mingli; Baran, Utku; Xi, Jiefeng; Sun, Ming-Ting; Wang, Ruikang; Li, Xingde; Lin, Lih Y


    This paper describes an endoscopic-inspired imaging system employing a micro-electromechanical system (MEMS) micromirror scanner to achieve beam scanning for optical coherence tomography (OCT) imaging. Miniaturization of a scanning mirror using MEMS technology can allow a fully functional imaging probe to be contained in a package sufficiently small for utilization in a working channel of a standard gastroesophageal endoscope. This work employs advanced image processing techniques to enhance the images acquired using the MEMS scanner to correct non-idealities in mirror performance. The experimental results demonstrate the effectiveness of the proposed technique.

  8. Optical coherence tomography investigations of ceramic lumineers (United States)

    Fernandes, Luana O.; Graça, Natalia D. R. L.; Melo, Luciana S. A.; Silva, Claudio H. V.; Gomes, Anderson S. L.


    Lumineers are veneer laminates used as an alternative for aesthetic dental solutions of the highest quality, but the only current means of its performance assessment is visual inspection. The objective of this study was to use the Optical Coherence Tomography (OCT) technique working in spectral domain to analyze in vivo in a single patient, 14 lumineers 180 days after cementation. It was possible to observe images in various kinds of changes in the cementing line and the laminate. It was concluded that the OCT is an effective and promising method to clinical evaluation of the cementing line in lumineers.

  9. Fourier phase in Fourier-domain optical coherence tomography. (United States)

    Uttam, Shikhar; Liu, Yang


    Phase of an electromagnetic wave propagating through a sample-of-interest is well understood in the context of quantitative phase imaging in transmission-mode microscopy. In the past decade, Fourier-domain optical coherence tomography has been used to extend quantitative phase imaging to the reflection-mode. Unlike transmission-mode electromagnetic phase, however, the origin and characteristics of reflection-mode Fourier phase are poorly understood, especially in samples with a slowly varying refractive index. In this paper, the general theory of Fourier phase from first principles is presented, and it is shown that Fourier phase is a joint estimate of subresolution offset and mean spatial frequency of the coherence-gated sample refractive index. It is also shown that both spectral-domain phase microscopy and depth-resolved spatial-domain low-coherence quantitative phase microscopy are special cases of this general theory. Analytical expressions are provided for both, and simulations are presented to explain and support the theoretical results. These results are further used to show how Fourier phase allows the estimation of an axial mean spatial frequency profile of the sample, along with depth-resolved characterization of localized optical density change and sample heterogeneity. Finally, a Fourier phase-based explanation of Doppler optical coherence tomography is also provided.

  10. En-face optical coherence tomography revival (United States)

    Bradu, Adrian; Kapinchev, Konstantin; Barnes, Frederick; Podoleanu, Adrian Gh.


    Quite recently, we introduced a novel Optical Coherence Tomography (OCT) method, termed as Master Slave OCT (MS-OCT), especially to deliver en-face images. MS-OCT operates like a time domain OCT, selecting signal from a selected depth only while scanning the laser beam across the sample. Time domain OCT allows real time production of an en-face image, although relatively slowly. As a major advance, the Master Slave method allows collection of signals from any number of depths, as required by the user. MS-OCT is an OCT method that does not require resampling of data and can be used to deliver en-face images from several depths simultaneously. However, as the MS-OCT method requires important computational resources, the number of multiple depth en-face images produced in real-time is limited. Here, we demonstrate that taking advantage of the parallel processing feature of the MS-OCT technology by harnessing the capabilities of graphics processing units (GPU)s, information from 384 depth positions is acquired in one raster with real time display of 40 en-face OCT images. These exhibit comparable resolution and sensitivity to the images produced using the traditional Fourier domain based method. The GPU facilitates versatile real time selection of parameters, such as the depth positions of the 40 images out of a set of 384 depth locations, as well as their axial resolution. Here, we present in parallel with the 40 en-face OCT images of a human tooth, a confocal microscopy lookalike image, together with two B-scan OCT images along rectangular directions.


    DEFF Research Database (Denmark)

    Osadchiy, Alexey Vladimirovich; Tafur Monroy, Idelfonso


    Coherent detection for spectrally encoded optical labels is proposed and experimentally demonstrated for three label tones spectrally spaced at 1 GHz. The proposed method utilizes a frequency swept local oscillator in a coherent receiver supported by digital signal processing for improved flexibi...... flexibility and upgradeability while reducing label detection subsystem complexity as compared with the conventional optical autocorrelation based approaches.......Coherent detection for spectrally encoded optical labels is proposed and experimentally demonstrated for three label tones spectrally spaced at 1 GHz. The proposed method utilizes a frequency swept local oscillator in a coherent receiver supported by digital signal processing for improved...

  12. Digital processing optical transmission and coherent receiving techniques

    CERN Document Server

    Binh, Le Nguyen


    With coherent mixing in the optical domain and processing in the digital domain, advanced receiving techniques employing ultra-high speed sampling rates have progressed tremendously over the last few years. These advances have brought coherent reception systems for lightwave-carried information to the next stage, resulting in ultra-high capacity global internetworking. Digital Processing: Optical Transmission and Coherent Receiving Techniques describes modern coherent receiving techniques for optical transmission and aspects of modern digital optical communications in the most basic lines. The

  13. Topology optimization for optical microlithography with partially coherent illumination

    DEFF Research Database (Denmark)

    Zhou, Mingdong; Lazarov, Boyan Stefanov; Sigmund, Ole


    This article revisits a topology optimization design approach for micro-manufacturing and extends it to optical microlithography with partially coherent illumination. The solution is based on a combination of two technologies, the topology optimization and the proximity error correction in microl......This article revisits a topology optimization design approach for micro-manufacturing and extends it to optical microlithography with partially coherent illumination. The solution is based on a combination of two technologies, the topology optimization and the proximity error correction...... in microlithography/nanolithography. The key steps include (i) modeling the physical inputs of the fabrication process, including the ultraviolet light illumination source and the mask, as the design variables in optimization and (ii) applying physical filtering and heaviside projection for topology optimization...

  14. Nonlinear complex diffusion approaches based on a novel noise estimation for noise reduction in phase-resolved optical coherence tomography (Conference Presentation) (United States)

    Xia, Shaoyan; Huang, Yong; Tan, Xiaodi


    Partial differential equation (PDE)-based nonlinear diffusion processes have been widely used for image denoising. In the traditional nonlinear anisotropic diffusion denoising techniques, behavior of the diffusion depends highly on the gradient of image. However, it is difficult to get a good effect if we use these methods to reduce noise in optical coherence tomography images. Because background has the gradient that is very similar to regions of interest, so background noise will be mistaken for edge information and cannot be reduced. Therefore, nonlinear complex diffusion approaches using texture feature(NCDTF) for noise reduction in phase-resolved optical coherence tomography is proposed here, which uses texture feature in OCT images and structural OCT images to remove noise in phase-resolved OCT. Taking into account the fact that texture between background and signal region is different, which can be linked with diffusion coefficient of nonlinear complex diffusion model, we use NCDTF method to reduce noises of structure and phase images first. Then, we utilize OCT structure images to filter phase image in OCT. Finally, to validate our method, parameters such as image SNR, contrast-to-noise ratio (CNR), equivalent number of looks (ENL), and edge preservation were compared between our approach and median filter, Gaussian filter, wavelet filter, nonlinear complex diffusion filter (NCDF). Preliminary results demonstrate that NCDTF method is more effective than others in keeping edges and denoising for phase-resolved OCT.

  15. Combatting nonlinear phase noise in coherent optical systems with an optimized decision processor based on machine learning (United States)

    Wang, Danshi; Zhang, Min; Cai, Zhongle; Cui, Yue; Li, Ze; Han, Huanhuan; Fu, Meixia; Luo, Bin


    An effective machine learning algorithm, the support vector machine (SVM), is presented in the context of a coherent optical transmission system. As a classifier, the SVM can create nonlinear decision boundaries to mitigate the distortions caused by nonlinear phase noise (NLPN). Without any prior information or heuristic assumptions, the SVM can learn and capture the link properties from only a few training data. Compared with the maximum likelihood estimation (MLE) algorithm, a lower bit-error rate (BER) is achieved by the SVM for a given launch power; moreover, the launch power dynamic range (LPDR) is increased by 3.3 dBm for 8 phase-shift keying (8 PSK), 1.2 dBm for QPSK, and 0.3 dBm for BPSK. The maximum transmission distance corresponding to a BER of 1 ×10-3 is increased by 480 km for the case of 8 PSK. The larger launch power range and longer transmission distance improve the tolerance to amplitude and phase noise, which demonstrates the feasibility of the SVM in digital signal processing for M-PSK formats. Meanwhile, in order to apply the SVM method to 16 quadratic amplitude modulation (16 QAM) detection, we propose a parameter optimization scheme. By utilizing a cross-validation and grid-search techniques, the optimal parameters of SVM can be selected, thus leading to the LPDR improvement by 2.8 dBm. Additionally, we demonstrate that the SVM is also effective in combating the laser phase noise combined with the inphase and quadrature (I/Q) modulator imperfections, but the improvement is insignificant for the linear noise and separate I/Q imbalance. The computational complexity of SVM is also discussed. The relatively low complexity makes it possible for SVM to implement the real-time processing.

  16. Adaptive optics optical coherence tomography for retina imaging

    Institute of Scientific and Technical Information of China (English)

    Guohua Shi; Yun Dai; Ling Wang; Zhihua Ding; Xuejun Rao; Yudong Zhang


    When optical coherence tomography (OCT) is used for human retina imaging, its transverse resolution is limited by the aberrations of human eyes. To overcome this disadvantage, a high resolution imaging system for living human retina, which consists of a time domain OCT system and a 37-elements adaptive optics (AO) system, has been developed. The AO closed loop rate is 20 frames per second, and the OCT has a 6.7-μm axial resolution. In this paper, this system is introduced and the high resolution imaging results for retina are presented.

  17. Optical coherence tomography technology and applications

    CERN Document Server

    Fujimoto, James


    Optical coherence tomography (OCT) is the optical analog of ultrasound imaging and is a powerful imaging technique that enables non-invasive, in vivo, high resolution, cross-sectional imaging in biological tissue.  Between 30 to 40 Million OCT imaging procedures are performed per year in ophthalmology.  The overall market is estimated at more than 0.5 Billion USD.  A new generation OCT technology was developed, dramatically increasing resolution and speed, achieving in vivo optical biopsy, i.e. the visualization of tissue architectural morphology in situ and in real time.  Functional extensions of OCT technology enable non-invasive, depth resolved functional assessment and imaging of tissue.  The book introduces OCT technology and applications not only from an optical and technological viewpoint, but also from the biomedical and clinical perspective. This second edition is widely extended and covers significantly more topics then the first edition of this book. The chapters are written leading intern...

  18. Digital signal processing techniques for coherent optical communication (United States)

    Goldfarb, Gilad

    Coherent detection with subsequent digital signal processing (DSP) is developed, analyzed theoretically and numerically and experimentally demonstrated in various fiber-optic transmission scenarios. The use of DSP in conjunction with coherent detection unleashes the benefits of coherent detection which rely on the preservaton of full information of the incoming field. These benefits include high receiver sensitivity, the ability to achieve high spectral-efficiency and the use of advanced modulation formats. With the immense advancements in DSP speeds, many of the problems hindering the use of coherent detection in optical transmission systems have been eliminated. Most notably, DSP alleviates the need for hardware phase-locking and polarization tracking, which can now be achieved in the digital domain. The complexity previously associated with coherent detection is hence significantly diminished and coherent detection is once gain considered a feasible detection alternative. In this thesis, several aspects of coherent detection (with or without subsequent DSP) are addressed. Coherent detection is presented as a means to extend the dispersion limit of a duobinary signal using an analog decision-directed phase-lock loop. Analytical bit-error ratio estimation for quadrature phase-shift keying signals is derived. To validate the promise for high spectral efficiency, the orthogonal-wavelength-division multiplexing scheme is suggested. In this scheme the WDM channels are spaced at the symbol rate, thus achieving the spectral efficiency limit. Theory, simulation and experimental results demonstrate the feasibility of this approach. Infinite impulse response filtering is shown to be an efficient alternative to finite impulse response filtering for chromatic dispersion compensation. Theory, design considerations, simulation and experimental results relating to this topic are presented. Interaction between fiber dispersion and nonlinearity remains the last major challenge

  19. Experimental demonstration of low-complexity fiber chromatic dispersion mitigation for reduced guard-interval OFDM coherent optical communication systems based on digital spectrum sub-band multiplexing. (United States)

    Malekiha, Mahdi; Tselniker, Igor; Nazarathy, Moshe; Tolmachev, Alex; Plant, David V


    We experimentally demonstrate a novel digital signal processing (DSP) structure for reduced guard-interval (RGI) OFDM coherent optical systems. The proposed concept is based on digitally slicing optical channel bandwidth into multiple spectrally disjoint sub-bands which are then processed in parallel. Each low bandwidth sub-band has a smaller delay-spread compared to a full-band signal. This enables compensation of both chromatic dispersion (CD) and polarization mode dispersion using a simple timing and one-tap-per-symbol frequency domain equalizer with a small cyclic prefix overhead. In terms of the DSP architecture, this allows for a highly efficient parallelization of DSP tasks performed over the received signal samples by deploying multiple processors running at a lower clock rate. It should be noted that this parallelization is performed in the frequency domain and it allows for flexible optical transceiver schemes. In addition, the resulting optical receiver is simplified due to the removal of the CD compensation equalizer compared to conventional RGI-OFDM systems. In this paper we experimentally demonstrate digital sub-banding of optical bandwidth. We test the system performance for different modulation formats (QPSK, 16QAM and 32QAM) over various transmission distances and optical launch powers using a 1.5% CP overhead in all scenarios. We also compare the proposed RGI-OFDM architecture performance against common single carrier modulation formats. At the same total data rate and signal bandwidth both systems have similar performance and transmission reach whereas the proposed method allows for a significant reduction of computational complexity due to removal of CD pre/post compensation equalizer.

  20. In vivo cellular visualization of the human retina using optical coherence tomography and adaptive optics

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, S S; Jones, S M; Chen, D C; Zawadzki, R J; Choi, S S; Laut, S P; Werner, J S


    Optical coherence tomography (OCT) sees the human retina sharply with adaptive optics. In vivo cellular visualization of the human retina at micrometer-scale resolution is possible by enhancing Fourier-domain optical-coherence tomography with adaptive optics, which compensate for the eye's optical aberrations.

  1. Optical coherence tomography for diagnosing periodontal disease (United States)

    Colston, Bill W., Jr.; Everett, Matthew J.; Da Silva, Luiz B.; Otis, Linda L.; Nathel, Howard


    We have, in this preliminary study, investigated the use of optical coherence tomography for diagnosis of periodontal disease. We took in vitro OCT images of the dental and periodontal tissues from a young pig and compared them to histological sections. These images distinguish tooth and soft tissue relationships that are important in diagnosing and assessing periodontal disease. We have imaged the attachment of gingiva to the tooth surface and located the cemento-enamel junction. This junction is an important reference point for defining attachment level in the diagnosis of periodontal disease. the boundary between enamel and dentin is also visible for most of the length of the anatomical crown, allowing quantitation of enamel thickness and character.

  2. Optical tractography of the mouse heart using polarization-sensitive optical coherence tomography. (United States)

    Wang, Yuanbo; Yao, Gang


    We developed a method to image myocardial fiber architecture in the mouse heart using a Jones matrix-based polarization-sensitive optical coherence tomography (PSOCT) system. The "cross-helical" laminar structure of myocardial fibers can be clearly visualized using this technology. The obtained myocardial fiber organization agrees well with existing knowledge acquired using conventional histology and diffusion tensor magnetic resonance imaging.

  3. Optical Coherence Tomography in Tissue Engineering (United States)

    Zhao, Youbo; Yang, Ying; Wang, Ruikang K.; Boppart, Stephen A.

    Tissue engineering holds the promise for a therapeutic solution in regenerative medicine. The primary goal of tissue engineering is the development of physiologically functional and biocompatible tissues/organs being implanted for the repair and replacement of damaged or diseased ones. Given the complexity in the developing processes of engineered tissues, which involves multi-dimensional interactions among cells of different types, three-dimensionally constructed scaffolds, and actively intervening bioreactors, a capable real-time imaging tool is critically required for expanding our knowledge about the developing process of desired tissues or organs. It has been recognized that optical coherence tomography (OCT), an emerging noninvasive imaging technique that provides high spatial resolution (up to the cellular level) and three-dimensional imaging capability, is a promising investigative tool for tissue engineering. This chapter discusses the existing and potential applications of OCT in tissue engineering. Example OCT investigations of the three major components of tissue engineering, i.e., cells, scaffolds, and bioreactors are overviewed. Imaging examples of OCT and its enabling functions and variants, e.g., Doppler OCT, polarization-sensitive OCT, optical coherence microscopy are emphasized. Remaining challenges in the application of OCT to tissue engineering are discussed, and the prospective solutions including the combination of OCT with other high-contrast and high-resolution modalities such as two-photon fluorescence microscopy are suggested as well. It is expected that OCT, along with its functional variants, will make important contributions toward revealing the complex cellular dynamics in engineered tissues as well as help us culture demanding tissue/organ implants that will advance regenerative medicine.

  4. General Strategy for Broadband Coherent Perfect Absorption and Multi-wavelength All-optical Switching Based on Epsilon-Near-Zero Multilayer Films (United States)

    Kim, Tae Young; Badsha, Md. Alamgir; Yoon, Junho; Lee, Seon Young; Jun, Young Chul; Hwangbo, Chang Kwon


    We propose a general, easy-to-implement scheme for broadband coherent perfect absorption (CPA) using epsilon-near-zero (ENZ) multilayer films. Specifically, we employ indium tin oxide (ITO) as a tunable ENZ material, and theoretically investigate CPA in the near-infrared region. We first derive general CPA conditions using the scattering matrix and the admittance matching methods. Then, by combining these two methods, we extract analytic expressions for all relevant parameters for CPA. Based on this theoretical framework, we proceed to study ENZ CPA in a single layer ITO film and apply it to all-optical switching. Finally, using an ITO multilayer of different ENZ wavelengths, we implement broadband ENZ CPA structures and investigate multi-wavelength all-optical switching in the technologically important telecommunication window. In our design, the admittance matching diagram was employed to graphically extract not only the structural parameters (the film thicknesses and incident angles), but also the input beam parameters (the irradiance ratio and phase difference between two input beams). We find that the multi-wavelength all-optical switching in our broadband ENZ CPA system can be fully controlled by the phase difference between two input beams. The simple but general design principles and analyses in this work can be widely used in various thin-film devices.

  5. Optical coherence tomography for endodontic imaging (United States)

    van Soest, G.; Shemesh, H.; Wu, M.-K.; van der Sluis, L. W. M.; Wesselink, P. R.


    In root canal therapy, complications frequently arise as a result of root fracture or imperfect cleaning of fins and invaginations. To date, there is no imaging method for nondestructive in vivo evaluation of the condition of the root canal, during or after treatment. There is a clinical need for a technique to detect defects before they give rise to complications. In this study we evaluate the ability of optical coherence tomography (OCT) to image root canal walls, and its capacity to identify complicating factors in root canal treatment. While the potential of OCT to identify caries has been explored before, endodontic imaging has not been reported. We imaged extracted lower front teeth after endodontic preparation and correlated these images to histological sections. A 3D OCT pullback scan was made with an endoscopic rotating optical fiber probe inside the root canal. All oval canals, uncleaned fins, risk zones, and one perforation that were detected by histology were also imaged by OCT. As an example of an area where OCT has clinical potential, we present a study of vertical root fracture identification with OCT.

  6. Optical Modulation Format Recognition in Stokes Space for Digital Coherent Receivers

    DEFF Research Database (Denmark)

    Borkowski, Robert; Zibar, Darko; Caballero Jambrina, Antonio;


    We report on a novel method for optical modulation format recognition based on Stokes parameters and variational expectation maximization algorithm. Discrimination among six different pol-muxed coherent modulation formats is successfully demonstrated in simulation and experiment....

  7. Optical coherent control in semiconductors: Fringe contrast and inhomogeneous broadening

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Vadim, Lyssenko; Hvam, Jørn Märcher


    Optical coherent control experiments in semiconductors reveal how inhomogeneous broadening must be taken into account in contrast to previous coherent control experiments in atomic and molecular systems. With spectral resolution elf the coherent control signal, the optical phases involved...... is observed in the four-wave mixing spectra as a function of phase-delay representing coherent control in the spectral domain. The spectral phase change of this modulation provides a spectroscopic tool to analyze contributions of inhomogeneous broadening to electronic resonances in semiconductor structures....

  8. Optical generation and control of quantum coherence in semiconductor nanostructures

    CERN Document Server

    Slavcheva, Gabriela


    The unprecedented control of coherence that can be exercised in quantum optics of atoms and molecules has stimulated increasing efforts in extending it to solid-state systems. One motivation to exploit the coherent phenomena comes from the emergence of the quantum information paradigm, however many more potential device applications ranging from novel lasers to spintronics are all bound up with issues in coherence. The book focuses on recent advances in the optical control of coherence in excitonic and polaritonic systems as model systems for the complex semiconductor dynamics towards the goal

  9. Digital coherent transceiver for optical communications: from design to implementation


    Anzuola Valencia, Esdras


    Establishing the basis of optical coherent transmission and detection which exploit digital signal processing (DSP) to optimize the performance of optical communication systems. [ANGLÈS] In this project we analyze the theoretical models of optical coherent communication systems as well as the front-end arquitectures used to implement them. Key concepts as balanced photo detection and quantum limit are explained and studied. Complex modulation schemes maximize spectral efficiency and power ...

  10. Optical Coherence Tomography–Based Corneal Power Measurement and Intraocular Lens Power Calculation Following Laser Vision Correction (An American Ophthalmological Society Thesis) (United States)

    Huang, David; Tang, Maolong; Wang, Li; Zhang, Xinbo; Armour, Rebecca L.; Gattey, Devin M.; Lombardi, Lorinna H.; Koch, Douglas D.


    Purpose: To use optical coherence tomography (OCT) to measure corneal power and improve the selection of intraocular lens (IOL) power in cataract surgeries after laser vision correction. Methods: Patients with previous myopic laser vision corrections were enrolled in this prospective study from two eye centers. Corneal thickness and power were measured by Fourier-domain OCT. Axial length, anterior chamber depth, and automated keratometry were measured by a partial coherence interferometer. An OCT-based IOL formula was developed. The mean absolute error of the OCT-based formula in predicting postoperative refraction was compared to two regression-based IOL formulae for eyes with previous laser vision correction. Results: Forty-six eyes of 46 patients all had uncomplicated cataract surgery with monofocal IOL implantation. The mean arithmetic prediction error of postoperative refraction was 0.05 ± 0.65 diopter (D) for the OCT formula, 0.14 ± 0.83 D for the Haigis-L formula, and 0.24 ± 0.82 D for the no-history Shammas-PL formula. The mean absolute error was 0.50 D for OCT compared to a mean absolute error of 0.67 D for Haigis-L and 0.67 D for Shammas-PL. The adjusted mean absolute error (average prediction error removed) was 0.49 D for OCT, 0.65 D for Haigis-L (P=.031), and 0.62 D for Shammas-PL (P=.044). For OCT, 61% of the eyes were within 0.5 D of prediction error, whereas 46% were within 0.5 D for both Haigis-L and Shammas-PL (P=.034). Conclusions: The predictive accuracy of OCT-based IOL power calculation was better than Haigis-L and Shammas-PL formulas in eyes after laser vision correction. PMID:24167323

  11. Integrated optical coherence tomography and optical coherence microscopy imaging of human pathology (United States)

    Lee, Hsiang-Chieh; Zhou, Chao; Wang, Yihong; Aquirre, Aaron D.; Tsai, Tsung-Han; Cohen, David W.; Connolly, James L.; Fujimoto, James G.


    Excisional biopsy is the current gold standard for disease diagnosis; however, it requires a relatively long processing time and it may also suffer from unacceptable false negative rates due to sampling errors. Optical coherence tomography (OCT) is a promising imaging technique that provide real-time, high resolution and three-dimensional (3D) images of tissue morphology. Optical coherence microscopy (OCM) is an extension of OCT, combining both the coherence gating and the confocal gating techniques. OCM imaging achieves cellular resolution with deeper imaging depth compared to confocal microscopy. An integrated OCT/OCM imaging system can provide co-registered multiscale imaging of tissue morphology. 3D-OCT provides architectural information with a large field of view and can be used to find regions of interest; while OCM provides high magnification to enable cellular imaging. The integrated OCT/OCM system has an axial resolution of kidney (19), were imaged with OCT and OCM within 2 to 6 hours after excision. The images were compared with H & E histology to identify characteristic features useful for disease diagnosis. The feasibility of visualizing human pathology using integrated OCT/OCM was demonstrated in the pathology laboratory settings.

  12. Ultrathin lensed fiber-optic probe for optical coherence tomography. (United States)

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


    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.

  13. Optical Coherence Tomography for the Assessment of Coronary Atherosclerosis and Vessel Response after Stent Implantation

    NARCIS (Netherlands)

    N. Gonzalo (Nieves)


    textabstractOptical Coherence Tomography (OCT) is a light-based imaging modality that can provide in vivo high-resolution images of the coronary artery with a level of resolution (axial 10-20 µm) ten times higher than intravascular ultrasound. The technique, uses low-coherent near infrarred light t

  14. Ultrafast coherent dynamics of a photonic crystal all-optical switch

    DEFF Research Database (Denmark)

    Colman, Pierre; Hansen, Per Lunnemann; Yu, Yi


    We present pump-probe measurements of an all-optical photonic crystal switch based on a nanocavity, resolving fast coherent temporal dynamics. The measurements demonstrate the importance of coherent effects typically neglected when considering nanocavity dynamics. In particular, we report...

  15. Invited Article: A compact optically coherent fiber frequency comb. (United States)

    Sinclair, L C; Deschênes, J-D; Sonderhouse, L; Swann, W C; Khader, I H; Baumann, E; Newbury, N R; Coddington, I


    We describe the design, fabrication, and performance of a self-referenced, optically coherent frequency comb. The system robustness is derived from a combination of an optics package based on polarization-maintaining fiber, saturable absorbers for mode-locking, high signal-to-noise ratio (SNR) detection of the control signals, and digital feedback control for frequency stabilization. The output is phase-coherent over a 1-2 μm octave-spanning spectrum with a pulse repetition rate of ∼200 MHz and a residual pulse-to-pulse timing jitter <3 fs well within the requirements of most frequency-comb applications. Digital control enables phase coherent operation for over 90 h, critical for phase-sensitive applications such as timekeeping. We show that this phase-slip free operation follows the fundamental limit set by the SNR of the control signals. Performance metrics from three nearly identical combs are presented. This laptop-sized comb should enable a wide-range of applications beyond the laboratory.

  16. Optical coherence tomography for retinal imaging in multiple sclerosis

    Directory of Open Access Journals (Sweden)

    Zimmermann H


    Full Text Available Hanna Zimmermann,1 Timm Oberwahrenbrock,1 Alexander U Brandt,1 Friedemann Paul,1–3 Jan Dörr1,2 1NeuroCure Clinical Research Center, 2Clinical and Experimental Multiple Sclerosis Research Center, 3Department of Neurology, Charité – Universitätsmedizin Berlin, Berlin, Germany Abstract: Visual disturbances caused by inflammatory and demyelinating processes of the visual system, mainly in the optic nerve, are a common symptom in multiple sclerosis (MS. Optical coherence tomography (OCT is a tool that is increasingly used for quantifying retinal damage in MS and other neurologic diseases. Based on spectral interferometry, it uses low-coherent infrared light to generate high-resolution spatial images of the retina. The retinal nerve fiber layer (RNFL consists of unmyelinated axons that form the optic nerve, and thus represents a part of the central nervous system. OCT allows for noninvasive measurements of RNFL thickness in micrometer resolution. With the help of OCT, researchers have managed to demonstrate that eyes of MS patients show distinct RNFL thinning after an event of acute optic neuritis in MS, and even subclinical damage in eyes with no previous optic neuritis. OCT is also a useful tool in terms of providing a differential diagnosis of MS toward, for example, neuromyelitis optica, a disease that usually shows stronger retinal thinning, or Susac syndrome, which is characterized by distinct patchy thinning of the inner retinal layers. RNFL thinning is associated with magnetic resonance imaging-derived measurements of the brain, such as whole-brain atrophy, gray and white matter atrophy, and optic radiation damage. These features suggest that OCT-derived retinal measurements are a complement for measuring central nervous system neurodegeneration in the context of clinical trials – for example, with neuroprotective substances. Keywords: visual function, multiple sclerosis, optic neuritis, retinal nerve fiber layer, neuromyelitis optica

  17. Optical coherence tomography of the prostate nerves (United States)

    Chitchian, Shahab

    Preservation of the cavernous nerves during prostate cancer surgery is critical in preserving a man's ability to have spontaneous erections following surgery. These microscopic nerves course along the surface of the prostate within a few millimeters of the prostate capsule, and they vary in size and location from one patient to another, making preservation of the nerves difficult during dissection and removal of a cancerous prostate gland. These observations may explain in part the wide variability in reported sexual potency rates (9--86%) following prostate cancer surgery. Any technology capable of providing improved identification, imaging, and visualization of the cavernous nerves during prostate cancer surgery would be of great assistance in improving sexual function after surgery, and result in direct patient benefit. Optical coherence tomography (OCT) is a noninvasive optical imaging technique capable of performing high-resolution cross-sectional in vivo and in situ imaging of microstructures in biological tissues. OCT imaging of the cavernous nerves in the rat and human prostate has recently been demonstrated. However, improvements in the OCT system and the quality of the images for identification of the cavernous nerves is necessary before clinical use. The following chapters describe complementary approaches to improving identification and imaging of the cavernous nerves during OCT of the prostate gland. After the introduction to OCT imaging of the prostate gland, the optimal wavelength for deep imaging of the prostate is studied in Chapter 2. An oblique-incidence single point measurement technique using a normal-detector scanning system was implemented to determine the absorption and reduced scattering coefficients, mua and m's , of fresh canine prostate tissue, ex vivo, from the diffuse reflectance profile of near-IR light as a function of source-detector distance. The effective attenuation coefficient, mueff, and the Optical Penetration Depth (OPD) were

  18. Evaluating the Use of Optical Coherence Tomography in Optic Neuritis

    Directory of Open Access Journals (Sweden)

    Fiona Costello


    Full Text Available Optic neuritis (ON is an inflammatory optic nerve injury, which is strongly associated with multiple sclerosis (MS. Axonal damage in the optic nerve manifests as retinal nerve fiber layer (RNFL deficits, which can be readily quantified with optical coherence tomography (OCT. The RNFL represents the most proximal region of the afferent visual pathway; and, as such, is a unique region of the central nervous system (CNS because it lacks myelin. Changes in retinal integrity can be correlated with reliable and quantifiable visual outcomes to provide a structural-functional paradigm of CNS injury. Because the eye provides a unique “view” into the effects of CNS inflammation, the ON “system model” may provide greater understanding about disease mechanisms, which underpin disability in MS. This review addresses the applications of OCT in study of ON patients, with specific reference to the published reports to date. The future role of OCT is discussed, both in terms of the potential gains and certain challenges associated with this evolving technology.

  19. Optical Biopsy Using Tissue Spectroscopy and Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Norman S Nishioka


    Full Text Available ‘Optical biopsy’ or ‘optical diagnostics’ is a technique whereby light energy is used to obtain information about the structure and function of tissues without disrupting them. In fluorescence spectroscopy, light energy (usually provided by a laser is used to excite tissues and the resulting fluorescence provides information about the target tissue. Its major gastrointestinal application has been in the evaluation of colonic polyps, in which it can reliably distinguish malignant from benign lesions. Optical coherence tomography (OCT has been used in the investigation of Barrett’s epithelium (and dysplasia, although a variety of other applications are feasible. For example, OCT could assist in the identification and staging of mucosal and submucosal neoplasms, the grading of inflammation in the stomach and intestine, the diagnosis of biliary tumours and the assessment of villous architecture. OCT differs from endoscopic ultrasound, a complementary modality, in that it has a much higher resolution but lesser depth of penetration. The images correlate with the histopathological appearance of tissues, and the addition of Doppler methods may enable it to evaluate the vascularity of tumours and the amount of blood flow in varices. Refinements in these new optical techniques will likely make them valuable in clinical practice, although their specific roles have yet to be determined.

  20. Spatial coherence at the output of multimode optical fibers. (United States)

    Efimov, Anatoly


    The modulus of the complex degree of coherence is directly measured at the output of a step-index multimode optical fiber using lateral-sheering, delay-dithering Mach-Zehnder interferometer. Pumping the multimode fiber with monochromatic light always results in spatially-coherent output, whereas for the broadband pumping the modal dispersion of the fiber leads to a partially coherent output. While the coherence radius is a function of the numerical aperture only, the residual coherence outside the main peak is an interesting function of two dimensionless parameters: the number of non-degenerate modes and the ratio of the modal dispersion to the coherence time of the source. We develop a simple model describing this residual coherence and verify its predictions experimentally.

  1. Anterior Eye Imaging with Optical Coherence Tomography (United States)

    Huang, David; Li, Yan; Tang, Maolong

    The development of corneal and anterior segment optical coherence tomography (OCT) technology has advanced rapidly in recently years. The scan geometry and imaging wavelength are both important choices to make in designing anterior segment OCT systems. Rectangular scan geometry offers the least image distortion and is now used in most anterior OCT systems. The wavelength of OCT light source affects resolution and penetration. An optimal choice of the OCT imaging wavelength (840, 1,050, or 1,310 nm) depends on the application of interest. Newer generation Fourier-domain OCT technology can provide scan speed 100-1000 times faster than the time-domain technology. Various commercial anterior OCT systems are available on the market. A wide spectrum of diagnostic and surgical applications using anterior segment OCT had been investigated, including mapping of corneal and epithelial thicknesses, keratoconus screening, measuring corneal refractive power, corneal surgery planning and evaluation in LASIK, intracorneal ring implantation, assessment of angle closure glaucoma, anterior chamber biometry and intraocular lens implants, intraocular lens power calculation, and eye bank donor cornea screening.

  2. Photodynamic therapy monitoring with optical coherence angiography (United States)

    Sirotkina, M. A.; Matveev, L. A.; Shirmanova, M. V.; Zaitsev, V. Y.; Buyanova, N. L.; Elagin, V. V.; Gelikonov, G. V.; Kuznetsov, S. S.; Kiseleva, E. B.; Moiseev, A. A.; Gamayunov, S. V.; Zagaynova, E. V.; Feldchtein, F. I.; Vitkin, A.; Gladkova, N. D.


    Photodynamic therapy (PDT) is a promising modern approach for cancer therapy with low normal tissue toxicity. This study was focused on a vascular-targeting Chlorine E6 mediated PDT. A new angiographic imaging approach known as M-mode-like optical coherence angiography (MML-OCA) was able to sensitively detect PDT-induced microvascular alterations in the mouse ear tumour model CT26. Histological analysis showed that the main mechanisms of vascular PDT was thrombosis of blood vessels and hemorrhage, which agrees with angiographic imaging by MML-OCA. Relationship between MML-OCA-detected early microvascular damage post PDT (within 24 hours) and tumour regression/regrowth was confirmed by histology. The advantages of MML-OCA such as direct image acquisition, fast processing, robust and affordable system opto-electronics, and label-free high contrast 3D visualization of the microvasculature suggest attractive possibilities of this method in practical clinical monitoring of cancer therapies with microvascular involvement. PMID:28148963

  3. Polarization sensitive optical coherence tomography detection method

    Energy Technology Data Exchange (ETDEWEB)

    Everett, M J; Sathyam, U S; Colston, B W; DaSilva, L B; Fried, D; Ragadio, J N; Featherstone, J D B


    This study demonstrates the potential of polarization sensitive optical coherence tomography (PS-OCT) for non-invasive in vivo detection and characterization of early, incipient caries lesions. PS-OCT generates cross-sectional images of biological tissue while measuring the effect of the tissue on the polarization state of incident light. Clear discrimination between regions of normal and demineralized enamel is first shown in PS-OCT images of bovine enamel blocks containing well-characterized artificial lesions. High-resolution, cross-sectional images of extracted human teeth are then generated that clearly discriminate between the normal and carious regions on both the smooth and occlusal surfaces. Regions of the teeth that appeared to be demineralized in the PS-OCT images were verified using histological thin sections examined under polarized light microscopy. The PS-OCT system discriminates between normal and carious regions by measuring the polarization state of the back-scattered 1310 nm light, which is affected by the state of demineralization of the enamel. Demineralization of enamel increases the scattereing coefficient, thus depolarizing the incident light. This study shows that PS-OCT has great potential for the detection, characterization, and monitoring of incipient caries lesions.

  4. Optical Coherence Tomography Angiography in Retinal Diseases. (United States)

    Chalam, K V; Sambhav, Kumar


    Optical coherence tomography angiography (OCTA) is a new, non-invasive imaging system that generates volumetric data of retinal and choroidal layers. It has the ability to show both structural and blood flow information. Split-spectrum amplitude-decorrelation angiography (SSADA) algorithm (a vital component of OCTA software) helps to decrease the signal to noise ratio of flow detection thus enhancing visualization of retinal vasculature using motion contrast. Published studies describe potential efficacy for OCTA in the evaluation of common ophthalmologic diseases such as diabetic retinopathy, age related macular degeneration (AMD), retinal vascular occlusions and sickle cell disease. OCTA provides a detailed view of the retinal vasculature, which allows accurate delineation of microvascular abnormalities in diabetic eyes and vascular occlusions. It helps quantify vascular compromise depending upon the severity of diabetic retinopathy. OCTA can also elucidate the presence of choroidal neovascularization (CNV) in wet AMD. In this paper, we review the knowledge, available in English language publications regarding OCTA, and compare it with the conventional angiographic standard, fluorescein angiography (FA). Finally, we summarize its potential applications to retinal vascular diseases. Its current limitations include a relatively small field of view, inability to show leakage, and tendency for image artifacts. Further larger studies will define OCTA's utility in clinical settings and establish if the technology may offer a non-invasive option of visualizing the retinal vasculature, enabling us to decrease morbidity through early detection and intervention in retinal diseases.

  5. Anatomic Optical Coherence Tomography of Upper Airways (United States)

    Chin Loy, Anthony; Jing, Joseph; Zhang, Jun; Wang, Yong; Elghobashi, Said; Chen, Zhongping; Wong, Brian J. F.

    The upper airway is a complex and intricate system responsible for respiration, phonation, and deglutition. Obstruction of the upper airways afflicts an estimated 12-18 million Americans. Pharyngeal size and shape are important factors in the pathogenesis of airway obstructions. In addition, nocturnal loss in pharyngeal muscular tone combined with high pharyngeal resistance can lead to collapse of the airway and periodic partial or complete upper airway obstruction. Anatomical optical coherence tomography (OCT) has the potential to provide high-speed three-dimensional tomographic images of the airway lumen without the use of ionizing radiation. In this chapter we describe the methods behind endoscopic OCT imaging and processing to generate full three dimensional anatomical models of the human airway which can be used in conjunction with numerical simulation methods to assess areas of airway obstruction. Combining this structural information with flow dynamic simulations, we can better estimate the site and causes of airway obstruction and better select and design surgery for patients with obstructive sleep apnea.

  6. Ultrahigh-resolution endoscopic optical coherence tomography (United States)

    Chen, Yu; Herz, Paul R.; Hsiung, Pei-Lin; Aguirre, Aaron D.; Mashimo, Hiroshi; Desai, Saleem; Pedrosa, Macos; Koski, Amanda; Schmitt, Joseph M.; Fujimoto, James G.


    Early detection of gastrointestinal cancer is essential for the patient treatment and medical care. Endoscopically guided biopsy is currently the gold standard for the diagnosis of early esophageal cancer, but can suffer from high false negative rates due to sampling errors. Optical coherence tomography (OCT) is an emerging medical imaging technology which can generate high resolution, cross-sectional images of tissue in situ and in real time, without the removal of tissue specimen. Although endoscopic OCT has been used successfully to identify certain pathologies in the gastrointestinal tract, the resolution of current endoscopic OCT systems has been limited to 10 - 15 m for clinical procedures. In this study, in vivo imaging of the gastrointestinal tract is demonstrated at a three-fold higher resolution (gastro-esophageal junction and colon on animal model display tissue microstructures and architectural details at high resolution, and the features observed in the OCT images are well-matched with histology. The clinical feasibility study is conducted through delivering OCT imaging catheter using standard endoscope. OCT images of normal esophagus, Barrett's esophagus, and esophageal cancers are demonstrated with distinct features. The ability of high resolution endoscopic OCT to image tissue morphology at an unprecedented resolution in vivo would facilitate the development of OCT as a potential imaging modality for early detection of neoplastic changes.

  7. International Conference on Coherence and Quantum Optics

    CERN Document Server



    This volume is composed of papers (invited and contributed) presented at the International Conference on Coherence and Quantum Optics held at the University of Hyderabad January 5-January 10, 1991. It has been organized by Professor Girish Agarwal and his colleagues at the School of Physics, University of Hyderabad, Hyder­ abad, India under partial support from the Department of Science and Technology, Government of India, International Center for Theoretical Physics, Trieste, Italy and the National Science Foundation, USA. Without the untiring efforts of Prof. Girish Agarwal and the members of his quantum office group, the Conference and the present volume would not have been possible. Some extraordinary circumstances resulted in a delay of the publication of the present volume. Our sincere apologies to all the authors. We deeply regret the inconvenience caused due to the delay. A debt of gratitude is due to Ms. Kim Bella for the excellent typing job of the different versions and the final version of the ma...

  8. Optical coherence tomography angiography in retinal diseases

    Directory of Open Access Journals (Sweden)

    K V Chalam


    Full Text Available Optical coherence tomography angiography (OCTA is a new, non-invasive imaging system that generates volumetric data of retinal and choroidal layers. It has the ability to show both structural and blood flow information. Split-spectrum amplitude-decorrelation angiography (SSADA algorithm (a vital component of OCTA software helps to decrease the signal to noise ratio of flow detection thus enhancing visualization of retinal vasculature using motion contrast. Published studies describe potential efficacy for OCTA in the evaluation of common ophthalmologic diseases such as diabetic retinopathy, age related macular degeneration (AMD, retinal vascular occlusions and sickle cell disease. OCTA provides a detailed view of the retinal vasculature, which allows accurate delineation of microvascular abnormalities in diabetic eyes and vascular occlusions. It helps quantify vascular compromise depending upon the severity of diabetic retinopathy. OCTA can also elucidate the presence of choroidal neovascularization (CNV in wet AMD. In this paper, we review the knowledge, available in English language publications regarding OCTA, and compare it with the conventional angiographic standard, fluorescein angiography (FA. Finally, we summarize its potential applications to retinal vascular diseases. Its current limitations include a relatively small field of view, inability to show leakage, and tendency for image artifacts. Further larger studies will define OCTA's utility in clinical settings and establish if the technology may offer a non-invasive option of visualizing the retinal vasculature, enabling us to decrease morbidity through early detection and intervention in retinal diseases.

  9. Integrated structural and functional optical imaging combining spectral-domain optical coherence and multiphoton microscopy

    CERN Document Server

    Vinegoni, C; Luo, W; Marks, D L; Ralston, T; Tan, W


    An integrated microscope that combines different optical techniques for simultaneous imaging is demonstrated. The microscope enables spectral-domain optical coherence microscopy based on optical backscatter, and multi-photon microscopy for the detection of two-photon fluorescence and second harmonic generation signals. The unique configuration of this integrated microscope allows for the simultaneous acquisition of both anatomical (structural) and functional imaging information with particular emphasis for applications in the fields of tissue engineering and cell biology. In addition, the contemporary analysis of the spectroscopic features can enhance contrast by differentiating among different tissue components.

  10. Propagation of Coherent Gaussian Schell-Model Beam Array in a Misaligned Optical System

    Institute of Scientific and Technical Information of China (English)

    ZHOU Pu; WANG Xiao-Lin; MA Yan-Xing; MA Hao-Tong; XU Xiao-Jun; LIU Ze-Jin


    @@ Based on a generalized Collins formula,the analytical formula for the propagation property of coherent Gaussian Schell-rnodel(GSM) beam array through a misaligned optical system is derived.As numerical examples,the propagation of a coherent GSM beam array in a typical misaligned optical system with a thin lens is evaluated.The influence of different misalignment parameters is calculated and the normalized-intensity distribution is graphically illustrated.%Based on a generalized Collins formula, the analytical formula for the propagation property of coherent Gaussian Schell-model (GSM) beam array through a misaligned optical system is derived. As numerical examples, the propagation of a coherent GSM beam array in a typical misaligned optical system with a thin lens is evaluated.The influence of different misalignment parameters is calculated and the normalized-intensity distribution is graphically illustrated.

  11. Optical coherent and envelope detection for photonic wireless communication links

    DEFF Research Database (Denmark)

    Prince, Kamau; Zibar, Darko; Yu, Xianbin;

    We present two novel optical detection techniques for radio over fiber (RoF) communication links. Firstly, we present recent results obtained with optical digital coherent detection of optical phase-modulated ROF signals supporting error-free transmission over 25 km standard SMF with BPSK and QPSK...

  12. Physical-layer network coding in coherent optical OFDM systems. (United States)

    Guan, Xun; Chan, Chun-Kit


    We present the first experimental demonstration and characterization of the application of optical physical-layer network coding in coherent optical OFDM systems. It combines two optical OFDM frames to share the same link so as to enhance system throughput, while individual OFDM frames can be recovered with digital signal processing at the destined node.

  13. Hard X-ray optics simulation using the coherent mode decomposition of Gaussian Schell model

    CERN Document Server

    Hua, Wenqiang; Song, Li; Li, Xiuhong; Wang, Jie


    The propagation of hard X ray beam from partially coherent synchrotron source is simulated by using the novel method based on the coherent mode decomposition of Gaussian Schell model and wave front propagation. We investigate how the coherency properties and intensity distributions of the beam are changed by propagation through optical elements. Here, we simulate and analyze the propagation of the partially coherent radiation transmitted through an ideal slit. We present the first simulations for focusing partially coherent synchrotron hard X ray beams using this novel method. And when compared with the traditional method which assumes the source is a totally coherent point source or completely incoherent, this method is proved to be more reasonable and can also demonstrate the coherence properties of the focusing beam. We also simulate the double slit experiment and the simulated results validate the academic analysis.

  14. Optical coherence tomography and Doppler optical coherence tomography in the gastrointestinal tract

    Institute of Scientific and Technical Information of China (English)

    Eugen Osiac; Adrian S(a)ftoiu; Dan Ionut Gheonea; Ion Mandrila; Radu Angelescu


    Optical coherence tomography(OCT)is a noninvasive,high-resolution,high-potential imaging method that has recently been introduced into medical investigations.A growing number of studies have used this technique in the field of gastroenterology in order to assist classical analyses.Lately,3D-imaging and Doppler capabilities have been developed in different configurations,which make this type of investigation more attractive.This paper reviews the principles and characteristics of OCT and Doppler-OCT in connection with analyses of the detection of normal and pathological structures,and with the possibility to investigate angiogenesis in the gastrointestinal tract.

  15. Frequency-time coherence for all-optical sampling without optical pulse source (United States)

    Preußler, Stefan; Raoof Mehrpoor, Gilda; Schneider, Thomas


    Sampling is the first step to convert an analogue optical signal into a digital electrical signal. The latter can be further processed and analysed by well-known electrical signal processing methods. Optical pulse sources like mode-locked lasers are commonly incorporated for all-optical sampling, but have several drawbacks. A novel approach for a simple all-optical sampling is to utilise the frequency-time coherence of each signal. The method is based on only using two coupled modulators driven with an electrical sine wave. Since no optical source is required, a simple integration in appropriate platforms, such as Silicon Photonics might be possible. The presented method grants all-optical sampling with electrically tunable bandwidth, repetition rate and time shift.

  16. Enhanced coherent OTDR for long span optical transmission lines containing optical fiber amplifiers (United States)

    Furukawa, Shin-Ichi; Tanaka, Kuniaki; Koyamada, Yahei; Sumida, Masatoyo


    We have newly constructed an enhanced coherent optical time domain reflectometer (C-OTDR) for use in testing optical cable spans in transmission lines containing erbium-doped fiber amplifiers (EDFA's), which is based on heterodyne detection using acousto-optic (AO) switches. In order to avoid any optical surges in the EDFA's in the transmission lines, optical dummy pulses were added between the signal pulses by an AO switch to keep the probe power from the C-OTDR as uniform as possible. We achieved a large single-way dynamic range of 42 dB with 5 dBm less probe power. The measurable portion of the fiber spans was more than 80 km in optical transmission lines containing EDFA's. This is twice the previously reported value.

  17. Three-Dimensional Optical Coherence Tomography (3D OCT) Project (United States)

    National Aeronautics and Space Administration — Applied Science Innovations, Inc. proposes to develop a new tool of 3D optical coherence tomography (OCT) for cellular level imaging at video frame rates and...

  18. Three-Dimensional Optical Coherence Tomography (3D OCT) Project (United States)

    National Aeronautics and Space Administration — Applied Science Innovations, Inc. proposes a new tool of 3D optical coherence tomography (OCT) for cellular level imaging at video frame rates and dramatically...

  19. Effective Linewidth of Semiconductor Lasers for Coherent Optical Data Links

    DEFF Research Database (Denmark)

    Iglesias Olmedo, Miguel; Pang, Xiaodan; Schatz, Richard


    We discuss the implications of using monolithically integrated semiconductor lasers in high capacity optical coherent links suitable for metro applications, where the integration capabilities of semiconductor lasers make them an attractive candidate to reduce transceiver cost. By investigating se...

  20. Approach to quantify two-dimensional strain of chick embryonic heart in early stage based on spectral domain optical coherence tomography (United States)

    Zhao, Yuqian; Dou, Shidan; Zhu, Wenlong; Wang, Yi; Xu, Tao; Wang, Fengwen; Ma, Zhenhe


    The heart undergoes remarkable changes during embryonic development due to genetic programming and epigenetic influences, in which mechanical loads is a key factor. As embryonic research development, an important goal is to develop mathematical models that describe the influence of mechanics on embryonic heart development. However, basic parameters for the modeling are difficult to acquire since the embryonic heart is tiny and beating fast in the early stages. Optical coherence tomography (OCT) technique provides depth-resolved image with high resolution and high acquisition speed in a noninvasive manner. In this paper, we performed 4D[(x,y,z) + t] scan on the outflow tract (OFT) of the chick embryonic heart at stage of HH18(~ 3 days of incubation) in vivo using spectral domain OCT (SDOCT). Parameters such as displacement and geometrical size of the OFT were extracted from the structural images of the SDOCT. Two-dimensional strain vector were solved using strain-displacement relations in curvilinear cylindrical coordinates based on kinetic theory of elasticity. Based on the geometrical size and other initial conditions, two-dimensional elasticity finite element model of the OFT myocardial wall deformation were established and then solved by direct frequency response method. Comparison between experimental data and simulation result shows the utility of the finite element models. Our results demonstrate that mathematical modeling based on parameters provided by SDOCT is a useful approach for studying cardiac development in early stage.

  1. Machine learning concepts in coherent optical communication systems

    DEFF Research Database (Denmark)

    Zibar, Darko; Schäffer, Christian G.


    Powerful statistical signal processing methods, used by the machine learning community, are addressed and linked to current problems in coherent optical communication. Bayesian filtering methods are presented and applied for nonlinear dynamic state tracking. © 2014 OSA.......Powerful statistical signal processing methods, used by the machine learning community, are addressed and linked to current problems in coherent optical communication. Bayesian filtering methods are presented and applied for nonlinear dynamic state tracking. © 2014 OSA....

  2. Experimental Demonstration of Spectral Intensity Optical Coherence Tomography

    CERN Document Server

    Ryczkowski, Piotr; Friberg, Ari T; Genty, Goëry


    We demonstrate experimentally quantum-inspired, spectral-domain intensity optical coherence tomography. We show that the technique allows for both axial resolution improvement and dispersion cancellation compared to conventional optical coherence tomography. The method does not involve scanning and it works with classical light sources and standard photodetectors. The measurements are in excellent agreement with the theoretical predictions. We also propose an approach that enables the elimination of potential artifacts arising from multiple interfaces.

  3. Bandpass sampling in heterodyne receivers for coherent optical access networks. (United States)

    Bakopoulos, Paraskevas; Dris, Stefanos; Schrenk, Bernhard; Lazarou, Ioannis; Avramopoulos, Hercules


    A novel digital receiver architecture for coherent heterodyne-detected optical signals is presented. It demonstrates the application of bandpass sampling in an optical communications context, to overcome the high sampling rate requirement of conventional receivers (more than twice the signal bandwidth). The concept is targeted for WDM coherent optical access networks, where applying heterodyne detection constitutes a promising approach to reducing optical hardware complexity. The validity of the concept is experimentally assessed in a 76 km WDM-PON scenario, where the developed DSP achieves a 50% ADC rate reduction with penalty-free operation.

  4. Anterior Segment Tomography with the Cirrus Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Eduardo B. Rodrigues


    Full Text Available Optical coherence tomography (OCT is an optical acquisition method to examine biological tissues. In recent years, OCT has become an important imaging technology used in diagnosing and following macular pathologies. Further development enabled application of optical coherence tomography in evaluation of the integrity of the nerve fiber layer, optic nerve cupping, anterior chamber angle, or corneal topography. In this manuscript we overview the use of OCT in the clinical practice to enable corneal, iris, ciliary body, and angle evaluation and diagnostics.

  5. Optical coherence tomography based microangiography for quantitative monitoring of structural and vascular changes in a rat model of acute uveitis in vivo: a preliminary study (United States)

    Choi, Woo June; Pepple, Kathryn L.; Zhi, Zhongwei; Wang, Ruikang K.


    Uveitis models in rodents are important in the investigation of pathogenesis in human uveitis and the development of appropriate therapeutic strategies for treatment. Quantitative monitoring of ocular inflammation in small animal models provides an objective metric to assess uveitis progression and/or therapeutic effects. We present a new application of optical coherence tomography (OCT) and OCT-based microangiography (OMAG) to a rat model of acute anterior uveitis induced by intravitreal injection of a killed mycobacterial extract. OCT/OMAG is used to provide noninvasive three-dimensional imaging of the anterior segment of the eyes prior to injection (baseline) and two days post-injection (peak inflammation) in rats with and without steroid treatments. OCT imaging identifies characteristic structural and vascular changes in the anterior segment of the inflamed animals when compared to baseline images. Characteristics of inflammation identified include anterior chamber cells, corneal edema, pupillary membranes, and iris vasodilation. In contrast, no significant difference from the control is observed for the steroid-treated eye. These findings are compared with the histology assessment of the same eyes. In addition, quantitative measurements of central corneal thickness and iris vessel diameter are determined. This pilot study demonstrates that OCT-based microangiography promises to be a useful tool for the assessment and management of uveitis in vivo.

  6. Imaging Granulomatous Lesions with Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Christina Banzhaf


    Full Text Available Aim: To investigate and compare the presentation of granulomatous lesions in optical coherence tomography (OCT images and compare this to previous studies of nonmelanoma skin tumors. Methods: Two patients with granulomas, tophi and granuloma annulare (GA, respectively, were photographed digitally, OCT-scanned and biopsied in the said order. Normal skin was OCT-scanned for comparison, but not biopsied. The OCT images from each lesion were compared with their histologic images as well as with OCT images with similar characteristics obtained from nonmelanoma skin tumors. Results: The OCT images of the tophi showed hyperreflective, rounded cloud-like structures in dermis, their upper part sharply delineated by a hyporeflective fringe. The deeper areas appeared blurred. The crystalline structures were delineated by a hyporeflective fringe. OCT images of GA showed two different structures in dermis: a hyporeflective rounded one, and one that was lobulated and wing-like. Conclusion: Granulomatous tissue surrounding urate deposits appeared as a clear hyporeflective fringe surrounding a light, hyperreflective area. The urate crystals appeared as hyperreflective areas, shielding the deeper part of dermis, meaning OCT could only visualize the upper part of the lesions. The lobulated, wing-like structure in GA may resemble diffuse GA or a dense lymphocytic infiltrate as seen on histology. The rounded structure in GA may represent an actual granuloma or either diffuse GA or a dense lymphocytic infiltrate as described above. This case suggests that OCT images granulomatous tissue as absorbent, hyporeflective areas, and urate crystals appear as reflective areas, obscuring the underlying tissue. In GA a new image shape looking like a wing has been found. The frequency, specificity and sensitivity of this new pattern in OCT imaging will require further studies.

  7. Self-Optical Coherence Tomography and Angiography

    Directory of Open Access Journals (Sweden)

    Ahmad M. Mansour


    Full Text Available Purpose: To present a new concept of self-optical coherence tomography (OCT and self-OCT angiography. Methods: The operator sits in the patient seat and manipulates the instrument body via the joystick with the dominant hand, while the dominant index is ready to press the capture button and while focusing on the fixation target. One senior ophthalmologist judged various OCT machines for ease of self-scan during a major ophthalmic convention. Separately, self-scans were also captured using a single OCT machine by one senior ophthalmologist and 5 junior optometrists and the scans were analyzed for both centration and image quality value (IQV, and compared to regular scans done by an operator. Results: Ten available OCT machines were tested for their ability to allow self-OCT. Machines that had one or more features of auto-alignment, auto-focus, and auto-shoot were ideal for self-OCT or self-OCT angiography. Self-scans done by the ophthalmologist (total 27 scans of right eye, mean IQV = 32.6, and 24 left eyes, mean IQV = 37.3, done over 9 months and 5 optometrists (total 24 scans, mean 34.8 done in one session were comparable to scans (total 11, mean IQV = 38.1 done by an operator for image quality. Decentration was very common in self-scans of the macula (37% right eye and 46% left eye versus 0% for scans of the right eye done by an operator. Conclusions: Self-OCT scans of the macular region can be done with good image quality but are often decentered. Advantages include privacy, potential use by ophthalmic health professionals, airspace station officers, and possible future home self-imaging of macula.

  8. Carious growth monitoring with optical coherence tomography (United States)

    Freitas, A. Z.; Zezell, D. M.; Mayer, M. P. A.; Ribeiro, A. C.; Gomes, A. S. L.; Vieira, N. D., Jr.


    Optical Coherence Tomography was used to monitor subsurface caries evolution process in vitro. Human tooth was used and bacteria were employed to induce caries lesions. Twenty-five human third molars, were used in this study. The teeth were cut longitudinally at mesio-distal direction; the surfaces were coated with nail varnish except for two squared windows (2x4 mm); at the cement-enamel junction. Artificial lesions were induced by a S. Mutans microbiological culture. The samples (N = 50) were divided into groups according to the demineralization time: 3, 5, 7, 9 and 11 days. The culture medium, was changed each 48 hours. After the demineralization process the samples were rinsed with double-deionized water and stored in a humid environment. The OCT system was implemented with average power of 96 μW in the sample arm, providing a 23 μm of axial resolution. The images were produced with lateral scans step of 10 μm. The detection system was composed by a detector, a demodulator and a computer. With the images generated by OCT it was possible to determine the lesion depth as function of sample exposition time to microbiological culture. We observed that the depth of the lesion in the root dentine increased from 70 μm to 230 μm, depending of exposure time, and follows the bacterial population growth law. This OCT system accurately depicts hard dental tissue and it was able to detect early caries in its structure, providing a powerful contactless high resolution image of lesions.

  9. Coherent phonons in carbon based nanostructures (United States)

    Sanders, G. D.; Nugraha, A. R. T.; Sato, K.; Kim, J.-H.; Lim, Y.-S.; Kono, J.; Saito, R.; Stanton, C. J.


    We have developed a theory for the generation and detection of coherent phonons in carbon based nanotstructures such as single walled nanotubes (SWNTs), graphene, and graphene nanoribbons. Coherent phonons are generated via the deformation potential electron/hole-phonon interaction with ultrafast photo-excited carriers. They modulate the reflectance or absorption of an optical probe pules on a THz time scale and might be useful for optical modulators. In our theory the electronic states are treated in a third nearest neighbor extended tight binding formalism which gives a good description of the states over the entire Brillouin zone while the phonon states are treated using valence force field models which include bond stretching, in-plane and out-of-plane bond bending, and bond twisting interactions up to fourth neighbor distances. We compare our theory to experiments for the low frequency radial breathing mode (RBM) in micelle suspended single-walled nanotubes (SWNTs). The analysis of such data provides a wealth of information on the dynamics and interplay of photons, phonons and electrons in these carbon based nanostructures.

  10. Frequency-time coherence for all-optical sampling without optical pulse source

    CERN Document Server

    Preussler, Stefan; Schneider, Thomas


    Sampling is the first step to convert an analogue optical signal into a digital electrical signal. The latter can be further processed and analysed by well-known electrical signal processing methods. Optical pulse sources like mode-locked lasers are commonly incorporated for all-optical sampling, but have several drawbacks. A novel approach for a simple all-optical sampling is to utilise the frequency-time coherence of each signal. The method is based on only using two coupled modulators driven with an electrical sine wave, allowing simple integration in appropriate platforms, such as Silicon Photonics. The presented method grants all-optical sampling with electrically tunable bandwidth, repetition rate and time shift.

  11. Comparison of event-based analysis of glaucoma progression assessed subjectively on visual fields and retinal nerve fibre layer attenuation measured by optical coherence tomography. (United States)

    Kaushik, Sushmita; Mulkutkar, Samyak; Pandav, Surinder Singh; Verma, Neelam; Gupta, Amod


    The purpose is to study the ability of an event-based analysis of retinal nerve fibre layer (RNFL) attenuation measured by Stratus(®) optical coherence tomography (OCT) and to detect progression across the spectrum of glaucoma. Adult glaucoma suspects, ocular hypertensives and glaucoma patients who had undergone baseline RNFL thickness measurement on Stratus OCT and reliable automated visual field examination by Humphrey's visual field analyser prior to March 2007 and had 5-year follow-up data were recruited. Progression on OCT was defined by two criteria: decrease in average RNFL thickness from baseline by at least 10 and 20 µ. Visual field progression was defined by the modified Hodapp-Parrish-Anderson criteria. Absolute and percentage change in RNFL thickness from baseline was compared in progressors and non-progressors on visual fields. Concordance between structural and functional progression was analysed. 318 eyes of 162 patients were analysed. 35 eyes (11 %) progressed by visual fields, 8 (2.5 %) progressed using the 20 µ loss criterion, while 30 eyes (9.4 %) progressed using the 10 µ loss criterion. In glaucoma suspects, mean absolute RNFL attenuation was 8.6 µ (12.1 % of baseline) in those who progressed to glaucoma by visual fields. OCT was more useful to detect progression in early glaucoma, but performed poorly in advanced glaucoma. The 10 µ criterion appears to be closer to visual field progression. However, the ability to detect progression varies considerably between functional and structural tools depending upon the severity of the disease.

  12. Three-dimensional Segmentation of Retinal Cysts from Spectral-domain Optical Coherence Tomography Images by the Use of Three-dimensional Curvelet Based K-SVD. (United States)

    Esmaeili, Mahdad; Dehnavi, Alireza Mehri; Rabbani, Hossein; Hajizadeh, Fedra


    This paper presents a new three-dimensional curvelet transform based dictionary learning for automatic segmentation of intraretinal cysts, most relevant prognostic biomarker in neovascular age-related macular degeneration, from 3D spectral-domain optical coherence tomography (SD-OCT) images. In particular, we focus on the Spectralis SD-OCT (Heidelberg Engineering, Heidelberg, Germany) system, and show the applicability of our algorithm in the segmentation of these features. For this purpose, we use recursive Gaussian filter and approximate the corrupted pixels from its surrounding, then in order to enhance the cystoid dark space regions and future noise suppression we introduce a new scheme in dictionary learning and take curvelet transform of filtered image then denoise and modify each noisy coefficients matrix in each scale with predefined initial 3D sparse dictionary. Dark pixels between retinal pigment epithelium and nerve fiber layer that were extracted with graph theory are considered as cystoid spaces. The average dice coefficient for the segmentation of cystoid regions in whole 3D volume and with-in central 3 mm diameter on the MICCAI 2015 OPTIMA Cyst Segmentation Challenge dataset were found to be 0.65 and 0.77, respectively.

  13. Three-dimensional Segmentation of Retinal Cysts from Spectral-domain Optical Coherence Tomography Images by the Use of Three-dimensional Curvelet Based K-SVD (United States)

    Esmaeili, Mahdad; Dehnavi, Alireza Mehri; Rabbani, Hossein; Hajizadeh, Fedra


    This paper presents a new three-dimensional curvelet transform based dictionary learning for automatic segmentation of intraretinal cysts, most relevant prognostic biomarker in neovascular age-related macular degeneration, from 3D spectral-domain optical coherence tomography (SD-OCT) images. In particular, we focus on the Spectralis SD-OCT (Heidelberg Engineering, Heidelberg, Germany) system, and show the applicability of our algorithm in the segmentation of these features. For this purpose, we use recursive Gaussian filter and approximate the corrupted pixels from its surrounding, then in order to enhance the cystoid dark space regions and future noise suppression we introduce a new scheme in dictionary learning and take curvelet transform of filtered image then denoise and modify each noisy coefficients matrix in each scale with predefined initial 3D sparse dictionary. Dark pixels between retinal pigment epithelium and nerve fiber layer that were extracted with graph theory are considered as cystoid spaces. The average dice coefficient for the segmentation of cystoid regions in whole 3D volume and with-in central 3 mm diameter on the MICCAI 2015 OPTIMA Cyst Segmentation Challenge dataset were found to be 0.65 and 0.77, respectively. PMID:27563573

  14. Spectral-domain optical coherence tomography on a silicon chip

    NARCIS (Netherlands)

    Akca, Bakiye Imran


    Optical coherence tomography (OCT) is a non-invasive optical technique for high-resolution cross-sectional imaging of specimens, with many applications in clinical medicine and industry (e.g. materials testing, quality assurance, and process control). Current state-of-the-art OCT systems operate in

  15. 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


    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.

  16. Epidermal segmentation in high-definition optical coherence tomography. (United States)

    Li, Annan; Cheng, Jun; Yow, Ai Ping; Wall, Carolin; Wong, Damon Wing Kee; Tey, Hong Liang; Liu, Jiang


    Epidermis segmentation is a crucial step in many dermatological applications. Recently, high-definition optical coherence tomography (HD-OCT) has been developed and applied to imaging subsurface skin tissues. In this paper, a novel epidermis segmentation method using HD-OCT is proposed in which the epidermis is segmented by 3 steps: the weighted least square-based pre-processing, the graph-based skin surface detection and the local integral projection-based dermal-epidermal junction detection respectively. Using a dataset of five 3D volumes, we found that this method correlates well with the conventional method of manually marking out the epidermis. This method can therefore serve to effectively and rapidly delineate the epidermis for study and clinical management of skin diseases.


    DEFF Research Database (Denmark)

    Hansen, Michael S.; Hove, Marianne N; Jensen, Hanne;


    PURPOSE: To report optical coherence tomography findings obtained in two patients with juvenile neuronal ceroid lipofuscinosis. METHODS: Two case reports. RESULTS: Two 7-year-old girls presented with decreased visual acuity, clumsiness, night blindness, and behavioral problems. Optical coherence...... tomography showed an overall reduction in thickness of the central retina, as well as the outer and the inner retinal layers. The degenerative retinal changes were the same, despite different mutations in the CLN3 gene. CONCLUSION: In these rare cases of juvenile neuronal ceroid lipofuscinosis, optical...

  18. On-chip microwave-to-optical quantum coherent converter based on a superconducting resonator coupled to an electro-optic microresonator

    CERN Document Server

    Javerzac-Galy, Clément; Bernier, Nathan; Toth, Laszlo D; Feofanov, Alexey K; Kippenberg, Tobias J


    We propose a device architecture capable of direct quantum electro-optical conversion of microwave to optical photons. The hybrid system consists of a planar superconducting microwave circuit coupled to an integrated whispering-gallery-mode microresonator made from an electro-optical material. We show that electro-optical (vacuum) coupling rates $g_0$ as large as$\\sim 2\\pi \\, \\mathcal{O}(10-100)$ kHz are achievable with currently available technology, due to the small mode volume of the planar microwave resonator. Operating at millikelvin temperatures, such a converter would enable high-efficiency conversion of microwave to optical photons. We analyze the added noise, and show that maximum conversion efficiency is achieved for a multi-photon cooperativity of unity which can be reached with optical power as low as $ \\mathcal{O}(1)\\,\\mathrm{mW} $.

  19. Coherent optical communication using polarization multiple-input-multiple-output. (United States)

    Han, Yan; Li, Guifang


    Polarization-division multiplexed (PDM) optical signals can potentially be demultiplexed by coherent detection and digital signal processing without using optical dynamic polarization control at the receiver. In this paper, we show that optical communications using PDM is analogous to wireless communications using multiple-input-multiple-output (MIMO) antennae and thus algorithms for channel estimation in wireless MIMO can be ready applied to optical polarization MIMO (PMIMO). Combined with frequency offset and phase estimation algorithms, simulations show that PDM quadrature phase-shift keying signals can be coherently detected by the proposed scheme using commercial semiconductor lasers while no optical phase locking and polarization control are required. This analogy further suggests the potential application of space-time coding in wireless communications to optical polarization MIMO systems and relates the problem of polarization-mode dispersion in fiber transmission to the multi-path propagation in wireless communications.

  20. Statistical analysis of motion contrast in optical coherence tomography angiography

    CERN Document Server

    Cheng, Yuxuan; Pan, Cong; Lu, Tongtong; Hong, Tianyu; Ding, Zhihua; Li, Peng


    Optical coherence tomography angiography (Angio-OCT), mainly based on the temporal dynamics of OCT scattering signals, has found a range of potential applications in clinical and scientific researches. In this work, based on the model of random phasor sums, temporal statistics of the complex-valued OCT signals are mathematically described. Statistical distributions of the amplitude differential (AD) and complex differential (CD) Angio-OCT signals are derived. The theories are validated through the flow phantom and live animal experiments. Using the model developed in this work, the origin of the motion contrast in Angio-OCT is mathematically explained, and the implications in the improvement of motion contrast are further discussed, including threshold determination and its residual classification error, averaging method, and scanning protocol. The proposed mathematical model of Angio-OCT signals can aid in the optimal design of the system and associated algorithms.

  1. Optical color-image encryption and synthesis using coherent diffractive imaging in the Fresnel domain. (United States)

    Chen, Wen; Chen, Xudong; Sheppard, Colin J R


    We propose a new method using coherent diffractive imaging for optical color-image encryption and synthesis in the Fresnel domain. An optical multiple-random-phase-mask encryption system is applied, and a strategy based on lateral translations of a phase-only mask is employed during image encryption. For the decryption, an iterative phase retrieval algorithm is applied to extract high-quality decrypted color images from diffraction intensity maps (i.e., ciphertexts). In addition, optical color-image synthesis is also investigated based on coherent diffractive imaging. Numerical results are presented to demonstrate feasibility and effectiveness of the proposed method. Compared with conventional interference methods, coherent diffractive imaging approach may open up a new research perspective or can provide an effective alternative for optical color-image encryption and synthesis.

  2. Coherent detection and digital signal processing for fiber optic communications (United States)

    Ip, Ezra

    The drive towards higher spectral efficiency in optical fiber systems has generated renewed interest in coherent detection. We review different detection methods, including noncoherent, differentially coherent, and coherent detection, as well as hybrid detection methods. We compare the modulation methods that are enabled and their respective performances in a linear regime. An important system parameter is the number of degrees of freedom (DOF) utilized in transmission. Polarization-multiplexed quadrature-amplitude modulation maximizes spectral efficiency and power efficiency as it uses all four available DOF contained in the two field quadratures in the two polarizations. Dual-polarization homodyne or heterodyne downconversion are linear processes that can fully recover the received signal field in these four DOF. When downconverted signals are sampled at the Nyquist rate, compensation of transmission impairments can be performed using digital signal processing (DSP). Software based receivers benefit from the robustness of DSP, flexibility in design, and ease of adaptation to time-varying channels. Linear impairments, including chromatic dispersion (CD) and polarization-mode dispersion (PMD), can be compensated quasi-exactly using finite impulse response filters. In practical systems, sampling the received signal at 3/2 times the symbol rate is sufficient to enable an arbitrary amount of CD and PMD to be compensated for a sufficiently long equalizer whose tap length scales linearly with transmission distance. Depending on the transmitted constellation and the target bit error rate, the analog-to-digital converter (ADC) should have around 5 to 6 bits of resolution. Digital coherent receivers are naturally suited for the implementation of feedforward carrier recovery, which has superior linewidth tolerance than phase-locked loops, and does not suffer from feedback delay constraints. Differential bit encoding can be used to prevent catastrophic receiver failure due

  3. Ultrarelativistic laser systems based on coherent beam combining (United States)

    Bagayev, S. N.; Trunov, V. I.; Pestryakov, E. V.; Frolov, S. A.; Leschenko, V. E.; Kirpichnikov, A. V.; Kokh, A. E.; Petrov, V. V.; Vasiliev, V. A.


    Conceptual design for femtosecond laser system of exawatt class, based on multi-channel amplifier and coherent field combining of petawatt amplifier channels with phase-frequency controlled radiation by optical clock are discussed. The scheme of start petawatt level few-cycle laser system with stable phase-frequency parameters determinated by the accuracy of the optical standard based on parametric amplification in big-size LBO crystals pumped by picosecond pulses is analyzed.

  4. Ultrarelativistic laser systems based on coherent beam combining

    Energy Technology Data Exchange (ETDEWEB)

    Bagayev, S. N.; Trunov, V. I.; Pestryakov, E. V.; Frolov, S. A.; Leschenko, V. E.; Kirpichnikov, A. V.; Kokh, A. E.; Petrov, V. V.; Vasiliev, V. A. [Institute of Laser Physics SB RAS, Ac. Lavrentyev' s prosp., 13/3, Novosibirsk (Russian Federation); Institute of Geology and Mineralogy SB RAS, Ac. Koptug' s prosp., 3, Novosibirsk (Russian Federation); Institute of Laser Physics SB RAS, Ac. Lavrentyev' s prosp., 13/3, Novosibirsk (Russian Federation)


    Conceptual design for femtosecond laser system of exawatt class, based on multi-channel amplifier and coherent field combining of petawatt amplifier channels with phase-frequency controlled radiation by optical clock are discussed. The scheme of start petawatt level few-cycle laser system with stable phase-frequency parameters determinated by the accuracy of the optical standard based on parametric amplification in big-size LBO crystals pumped by picosecond pulses is analyzed.

  5. Optical probe design with extended depth-of-focus for optical coherence microscopy and optical coherence tomography (United States)

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


    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.

  6. Waterline extraction in optical images and InSAR coherence maps based on the geodesic time concept (United States)

    Soares, Fernando; Nico, Giovanni


    An algorithm for waterline extraction from SAR images is presented based on the estimation of the geodesic path, or minimal path (MP) between two pixels on the waterline. For two given pixels, geodesic time is determined in terms of the time shortest path, between them. The MP is determined by estimating the mean value for all pairs of neighbor pixels that can be part of a possible path connecting the initial given pixels. A MP is computed as the sum of those two geodesic image functions. In general, a MP is obtained with the knowledge of two end pixels. Based on the 2-dimensional spreading of the estimated geodesic time function, the concepts of propagation energy and strong pixels are introduced and tested for the waterline extraction by marking only one pixel in the image.

  7. Optical Coherence Tomography: Modeling and Applications

    DEFF Research Database (Denmark)

    Thrane, Lars

    in previous theoretical models of OCT systems. It is demonstrated that the shower curtain effect is of utmost importance in the theoretical description of an OCT system. The analytical model, together with proper noise analysis of the OCT system, enables calculation of the SNR, where the optical properties...... geometry, i.e., reflection geometry, is developed. As in the new OCT model, multiple scattered photons has been taken into account together with multiple scattering effects. As an important result, a novel method of creating images based on measurements of the momentum width of the Wigner phase......An analytical model is presented that is able to describe the performance of OCT systems in both the single and multiple scattering regimes simultaneously. This model inherently includes the shower curtain effect, well-known for light propagation through the atmosphere. This effect has been omitted...

  8. The Development, Commercialization, and Impact of Optical Coherence Tomography. (United States)

    Fujimoto, James; Swanson, Eric


    This review was written for the special issue of IOVS to describe the history of optical coherence tomography (OCT) and its evolution from a nonscientific, historic perspective. Optical coherence tomography has become a standard of care in ophthalmology, providing real-time information on structure and function - diagnosing disease, evaluating progression, and assessing response to therapy, as well as helping to understand disease pathogenesis and create new therapies. Optical coherence tomography also has applications in multiple clinical specialties, fundamental research, and manufacturing. We review the early history of OCT describing how research and development evolves and the important role of multidisciplinary collaboration and expertise. Optical coherence tomography had its origin in femtosecond optics, but used optical communications technologies and required advanced engineering for early OCT prototypes, clinical feasibility studies, entrepreneurship, and corporate development in order to achieve clinical acceptance and clinical impact. Critical advances were made by early career researchers, clinician scientists, engineering experts, and business leaders, which enabled OCT to have a worldwide impact on health care. We introduce the concept of an "ecosystem" consisting of research, government funding, collaboration and competition, clinical studies, innovation, entrepreneurship and industry, and impact - all of which must work synergistically. The process that we recount is long and challenging, but it is our hope that it might inspire early career professionals in science, engineering, and medicine, and that the clinical and research community will find this review of interest.

  9. Reflective type objective based spectral-domain phase-sensitive optical coherence tomography for high-sensitive structural and functional imaging of cochlear microstructures through intact bone of an excised guinea pig cochlea (United States)

    Subhash, Hrebesh M.; Wang, Ruikang K.; Chen, Fangyi; Nuttall, Alfred L.


    Most of the optical coherence tomographic (OCT) systems for high resolution imaging of biological specimens are based on refractive type microscope objectives, which are optimized for specific wave length of the optical source. In this study, we present the feasibility of using commercially available reflective type objective for high sensitive and high resolution structural and functional imaging of cochlear microstructures of an excised guinea pig through intact temporal bone. Unlike conventional refractive type microscopic objective, reflective objective are free from chromatic aberrations due to their all-reflecting nature and can support a broadband of spectrum with very high light collection efficiency.

  10. High-resolution second harmonic optical coherence tomography (United States)

    Jiang, Yi; Tomov, Ivan V.; Wang, Yimin; Chen, Zhongping


    A high-resolution Second Harmonic Optical Coherence Tomography (SH-OCT) system is demonstrated using a spectrum broadened femtosecond Ti:sapphire laser. An axial resolution of 4.2 μm at the second harmonic wave center wavelength of 400 nm has been achieved. Because the SH-OCT system uses the second harmonic generation signals that strongly depend on the orientation, polarization and local symmetry properties of chiral molecules, this technique provides unique contrast enhancement to conventional optical coherence tomography. The system is applied to image biological tissues like the rat-tail tendon. Images of highly organized collagen fibrils in the rat-tail tendon have been demonstrated.

  11. Evaluation of microfluidic channels with optical coherence tomography

    KAUST Repository

    Czajkowski, J.


    Application of time domain, ultra high resolution optical coherence tomography (UHR-OCT) in evaluation of microfluidic channels is demonstrated. Presented study was done using experimental UHR-OCT device based on a Kerr-lens mode locked Ti:sapphire femtosecond laser, a photonic crystal fibre and modified, free-space Michelson interferometer. To show potential of the technique, microfluidic chip fabricated by VTT Center for Printed Intelligence (Oulu, Finland) was measured. Ability for full volumetric reconstruction in non-contact manner enabled complete characterization of closed entity of a microfluidic channel without contamination and harm for the sample. Measurement, occurring problems, and methods of postprocessing for raw data are described. Results present completely resolved physical structure of the channel, its spatial dimensions, draft angles and evaluation of lamination quality.

  12. Optical coherence tomography for imaging of skin and skin diseases

    DEFF Research Database (Denmark)

    Mogensen, Mette; Thrane, Lars; Jørgensen, Thomas Martini


    Optical coherence tomography (OCT) is an emerging imaging technology based on light reflection. It provides real-time images with up to 2-mm penetration into the skin and a resolution of approximately 10 μm. It is routinely used in ophthalmology. The normal skin and its appendages have been studied......, as have many diseases. The method can provide accurate measures of epidermal and nail changes in normal tissue. Skin cancer and other tumors, as well as inflammatory diseases, have been studied and good agreement found between OCT images and histopathological architecture. OCT also allows noninvasive...... monitoring of morphologic changes in skin diseases and may have a particular role in the monitoring of medical treatment of nonmelanoma skin cancer. The technology is however still evolving and continued technological development will necessitate an ongoing evaluation of its diagnostic accuracy. Several...

  13. Real-time reception of multi-gigabit coherent optical OFDM signals. (United States)

    Yang, Qi; Chen, Simin; Ma, Yiran; Shieh, William


    Coherent Optical OFDM (CO-OFDM) has been demonstrated for delivering superior performance in spectral efficiency, receiver sensitivity, and polarization-dispersion resilience. Fueled by the rapid advancement in semiconductor technology, high-speed field-programmable gate arrays (FPGA) and analogue-to-digital-converters/digital-to-analogue converters (ADC/DACs) have been increasingly adopted for digital signal processing in optical communications. In this paper, we report the first FPGA-based real-time implementation of coherent optical OFDM (CO-OFDM) receiver with a transmission rate up to 3.1 Gb/s. Several basic aspects of CO-OFDM signal processing are described in detail, and the BER sensitivity performance are evaluated in real-time. To the best of our knowledge, we have achieved the record real-time reception date rate for a single-input single-output (SISO) coherent OFDM signal, in either RF domain or optical domain.

  14. Experimental characterization of X-ray transverse coherence in the presence of beam transport optics

    DEFF Research Database (Denmark)

    Chubar, O.; Fluerasu, A.; Chu, Y.S.


    be significantly affected by the new shape of the focused beam phase-space. At the same time, optical element imperfections still have a negative impact on the transverse coherence. In such situations, which are frequently encountered in experiments at beamlines, the quantitative interpretation of a measured...... propagation based simulations show, in particular, that new generation 1D Beryllium Compound Refractive Lenses [3, 4] do not reduce the X-ray transverse coherence in any significant manner. © 2013 IOP Publishing Ltd....

  15. Handheld probes and galvanometer scanning for optical coherence tomography (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.


    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.

  16. Optical Coherence Tomography: Clinical Applications in Medical Practice

    Directory of Open Access Journals (Sweden)

    Abdullah Al-Mujaini


    Full Text Available Optical Coherence Tomography (OCT is a success story of scientific and technological co-operation between a physicist and a clinician. The concept of cross-sectional imaging revolutionalized the applicability of OCT in the medical profession. OCT is a non-contact, topographic, biomicroscopic device that provides high resolution, cross-sectional digital images of live biological tissues in vivo and in real time. OCT is based on the property of tissues to reflect and backscatter light involving low-coherence interferometry. The spatial resolution of as little as 3 microns or even less has allowed us to study tissues almost at a cellular level. Overall, OCT is an invaluable adjunct in the diagnosis and follow up of many diseases of both anterior and posterior segments of the eye, primarily or secondary to systemic diseases. The digitalization and advanced software has made it possible to store and retrieve huge patient data for patient services, clinical applications and academic research. OCT has revolutionized the sensitivity and specificity of diagnosis, follow up and response to treatment in almost all fields of clinical practice involving primary ocular pathologies and secondary ocular manifestations in systemic diseases like diabetes mellitus, hypertension, vascular and neurological diseases, thus benefitting non-ophthalmologists as well. Systemically, OCT is proving to be a helpful tool in substantiating early diagnosis in diseases like multiple sclerosis and drug induced retinopathies by detecting early changes in morphology of the retinal nerve fiber layer.

  17. Investigation of optical currents in coherent and partially coherent vector fields

    DEFF Research Database (Denmark)

    Angelsky, O. V.; Gorsky, M. P.; Maksimyak, P. P.;


    in the arrangements of two-wave and four-wave superposition on the characteris-tics of the microparticle’s motion has been analyzed. The prospects of stud-ying temporal coherence using the proposed approach are made. For the first time, the possibility of diagnostics of optical currents in liquids caused...

  18. Single qubit operations with base squeezed coherent states (United States)

    Podoshvedov, Sergey A.


    In quantum computing with base either coherent or squeezed coherent states, information is encoded into coherent states with opposite amplitudes. To exploit the base states in quantum computation, we need arbitrary qubit rotations plus a two-qubit gate such as controlled-Z gate to simulate any multiqubit unitary transformations. We develop an approach to realize single qubit operations with the base squeezed coherent states. The optical setup requires a resource of the base squeezed coherent states, unbalanced beam splitter whose transmittance tends to unity and photon counters in auxiliary modes. A successful two-photon subtraction from transmitted beam is heralded by two-photon click in auxiliary modes where tiny part of the initial beam is detected. The thrust of the method is that it achieves a high fidelity without photodetectors with a high efficiency or a single-photon resolution. We observe that there is wide diapason of values of the parameters that provide performance of single qubit operations with the base states. The problem is resolved in Wigner representation to take into account imperfections of the optical devices.

  19. Effects of laser phase noise on the performance of optical coherent receivers

    Institute of Scientific and Technical Information of China (English)

    LIU Ji-hong; LI Zhao-lin; LIANG Meng


    Laser phase noise (LPN) plays an important role in optical coherent systems.Based on the algorithm of Viterbi-Viterbi carrier phase estimation (CPE),the effects of LPN imposed on the coherent receivers are investigated for quadrature phase shift keying (QPSK),8 phase shift keying (8PSK) and 16-quadrature amplitude modulation (16-QAM) optical coherent systems,respectively.The simulation results show that the optimal block length in the phase estimation algorithm is a tradeoff between LPN and additive white Gaussian noise (AWGN),and depends on the level of modulation formats.The resolution requirements of analog to digital converter (ADC) in the coherent receivers are independent of LPN or the level of modulation formats.For the bit error rate (BER) of 10-3,the required bit number of ADC is 6,and the gain is marginal for the higher resolution.

  20. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging (United States)

    Cua, Michelle; Wahl, Daniel J.; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J.; Jian, Yifan; Sarunic, Marinko V.


    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems.

  1. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging. (United States)

    Cua, Michelle; Wahl, Daniel J; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J; Jian, Yifan; Sarunic, Marinko V


    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems.

  2. Digital Signal Processing for Optical Coherent Communication Systems

    DEFF Research Database (Denmark)

    Zhang, Xu

    In this thesis, digital signal processing (DSP) algorithms are studied to compensate for physical layer impairments in optical fiber coherent communication systems. The physical layer impairments investigated in this thesis include optical fiber chromatic dispersion, polarization demultiplexing......, light sources frequency and phase offset and phase noise. The studied DSP algorithms are considered as key building blocks in digital coherent receivers for the next generation of optical communication systems such as 112-Gb/s dual polarization (DP) quadrature phase shift keying (QPSK) optical......) equalizer algorithms are implemented to reduce the inter channel interference (ICI). This PhD thesis also investigates a parallel block-divided overlapped chromatic dispersion DSP compensation algorithm. The essential benefit of using a parallel chromatic dispersion compensation algorithm is that it demands...

  3. Multimodal full-field optical coherence tomography on biological tissue: toward all optical digital pathology (United States)

    Harms, F.; Dalimier, E.; Vermeulen, P.; Fragola, A.; Boccara, A. C.


    Optical Coherence Tomography (OCT) is an efficient technique for in-depth optical biopsy of biological tissues, relying on interferometric selection of ballistic photons. Full-Field Optical Coherence Tomography (FF-OCT) is an alternative approach to Fourier-domain OCT (spectral or swept-source), allowing parallel acquisition of en-face optical sections. Using medium numerical aperture objective, it is possible to reach an isotropic resolution of about 1x1x1 ìm. After stitching a grid of acquired images, FF-OCT gives access to the architecture of the tissue, for both macroscopic and microscopic structures, in a non-invasive process, which makes the technique particularly suitable for applications in pathology. Here we report a multimodal approach to FF-OCT, combining two Full-Field techniques for collecting a backscattered endogeneous OCT image and a fluorescence exogeneous image in parallel. Considering pathological diagnosis of cancer, visualization of cell nuclei is of paramount importance. OCT images, even for the highest resolution, usually fail to identify individual nuclei due to the nature of the optical contrast used. We have built a multimodal optical microscope based on the combination of FF-OCT and Structured Illumination Microscopy (SIM). We used x30 immersion objectives, with a numerical aperture of 1.05, allowing for sub-micron transverse resolution. Fluorescent staining of nuclei was obtained using specific fluorescent dyes such as acridine orange. We present multimodal images of healthy and pathological skin tissue at various scales. This instrumental development paves the way for improvements of standard pathology procedures, as a faster, non sacrificial, operator independent digital optical method compared to frozen sections.

  4. All-optical coherent control of vacuum Rabi oscillations

    CERN Document Server

    Bose, Ranojoy; Choudhury, Kaushik Roy; Solomon, Glenn S; Waks, Edo


    When an atom strongly couples to a cavity, it can undergo coherent vacuum Rabi oscillations. Controlling these oscillatory dynamics quickly relative to the vacuum Rabi frequency enables remarkable capabilities such as Fock state generation and deterministic synthesis of quantum states of light, as demonstrated using microwave frequency devices. At optical frequencies, however, dynamical control of single-atom vacuum Rabi oscillations remains challenging. Here, we demonstrate coherent transfer of optical frequency excitation between a single quantum dot and a cavity by controlling vacuum Rabi oscillations. We utilize a photonic molecule to simultaneously attain strong coupling and a cavity-enhanced AC Stark shift. The Stark shift modulates the detuning between the two systems on picosecond timescales, faster than the vacuum Rabi frequency. We demonstrate the ability to add and remove excitation from the cavity, and perform coherent control of light-matter states. These results enable ultra-fast control of atom...

  5. Spectral domain optical coherence tomography and microperimetry in foveal hypoplasia

    Directory of Open Access Journals (Sweden)

    Swakshyar Saumya Pal


    Full Text Available A case of foveal hypoplasia associated with ocular albinism with anatomic and functional changes by various techniques using spectral domain optical coherence tomography (SD-OCT, microperimeter and confocal scanning laser ophthalmoscope is described. This case highlights the importance of microperimeter in detecting the functional abnormalities of vision and SD-OCT in identifying the retinal laminar abnormalities in foveal hypoplasia.

  6. Generation of optical coherent state superpositions for quantum information processing

    DEFF Research Database (Denmark)

    Tipsmark, Anders


    I dette projektarbejde med titlen “Generation of optical coherent state superpositions for quantum information processing” har målet været at generere optiske kat-tilstande. Dette er en kvantemekanisk superpositions tilstand af to koherente tilstande med stor amplitude. Sådan en tilstand er...

  7. Complex sine-Gordon Equation in Coherent Optical Pulse Propagation

    CERN Document Server

    Park, Q H


    It is shown that the McCall-Hahn theory of self-induced transparency in coherent optical pulse propagation can be identified with the complex sine-Gordon theory in the sharp line limit. We reformulate the theory in terms of the deformed gauged Wess-Zumino-Witten sigma model and address various new aspects of self-induced transparency.

  8. Optical Coherence Tomography for Brain Imaging (United States)

    Liu, Gangjun; Chen, Zhongping

    Recently, there has been growing interest in using OCT for brain imaging. A feasibility study of OCT for guiding deep brain probes has found that OCT can differentiate the white matter and gray matter because the white matter tends to have a higher peak reflectivity and steeper attenuation rate compared to gray matter. In vivo 3D visualization of the layered organization of a rat olfactory bulb with OCT has been demonstrated. OCT has been used for single myelin fiber imaging in living rodents without labeling. The refractive index in the rat somatosensory cortex has also been measured with OCT. In addition, functional extension of OCT, such as Doppler-OCT (D-OCT), polarization sensitive-OCT (PS-OCT), and phase-resolved-OCT (PR-OCT), can image and quantify physiological parameters in addition to the morphological structure image. Based on the scattering changes during neural activity, OCT has been used to measure the functional activation in neuronal tissues. PS-OCT, which combines polarization sensitive detection with OCT to determine tissue birefringence, has been used for the localization of nerve fiber bundles and the mapping of micrometer-scale fiber pathways in the brain. D-OCT, also named optical Doppler tomography (ODT), combines the Doppler principle with OCT to obtain high resolution tomographic images of moving constituents in highly scattering biological tissues. D-OCT has been successfully used to image cortical blood flow and map the blood vessel network for brain research. In this chapter, the principle and technology of OCT and D-OCT are reviewed and examples of potential applications are described.

  9. Full wave model of image formation in optical coherence tomography applicable to general samples. (United States)

    Munro, Peter R T; Curatolo, Andrea; Sampson, David D


    We demonstrate a highly realistic model of optical coherence tomography, based on an existing model of coherent optical microscopes, which employs a full wave description of light. A defining feature of the model is the decoupling of the key functions of an optical coherence tomography system: sample illumination, light-sample interaction and the collection of light scattered by the sample. We show how such a model can be implemented using the finite-difference time-domain method to model light propagation in general samples. The model employs vectorial focussing theory to represent the optical system and, thus, incorporates general illumination beam types and detection optics. To demonstrate its versatility, we model image formation of a stratified medium, a numerical point-spread function phantom and a numerical phantom, based upon a physical three-dimensional structured phantom employed in our laboratory. We show that simulated images compare well with experimental images of a three-dimensional structured phantom. Such a model provides a powerful means to advance all aspects of optical coherence tomography imaging.

  10. Coherent LQG Control, Free-Carrier Oscillations, Optical Ising Machines and Pulsed OPO Dynamics

    CERN Document Server

    Hamerly, Ryan


    Broadly speaking, this thesis is about nonlinear optics, quantum mechanics, and computing. More specifically, it covers four main topics: Coherent LQG Control, Free-Carrier Oscillations, Optical Ising Machines and Pulsed OPO Dynamics. Tying them all together is a theory of open quantum systems called the SLH model, which I introduce in Chapters 1-2. The SLH model is a general framework for open quantum systems that interact through bosonic fields, and is the basis for the quantum circuit theory developed in the text. Coherent LQG control is discussed in Chapters 3-4, where I demonstrate that coherent feedback outperforms measurement-based feedback for certain linear quadratic-Gaussian (LQG) problems, and explain the discrepancy by the former's simultaneous utilization of both light quadratures. Semiclassical truncated-Wigner techniques for quantum-optical networks are discussed in Chapter 5, leading to a thorough discussion of quantum noise in systems with free-carrier nonlinearities (Chapter 6), comparison t...

  11. Large area full-field optical coherence tomography (United States)

    Chang, Shoude; Sherif, Sherif; Flueraru, Costel


    Optical Coherence Tomography (OCT) is a fundamentally new type of optical imaging technology. OCT performs high resolution, cross-sectional tomographic imaging of the internal structure in materials and biological systems. The biomedical applications of the OCT imaging systems have been developed for diagnostics of ophthalmology, dermatology, dentistry and cardiology. Most of existing OCT systems use point-scanning based technology, however, the 3-axis scanning makes the system slow and cumbersome. A few OCT systems working directly on 2D full-field images were reported, however, they are designed to work in a relatively small area, around couple of hundred microns square. In this paper, we present a design and implementation of a full-field OCT imaging system for acquiring tomography and with a working area around 15mm by 15 mm. The problems rising from full-field OCT are addressed and analyzed. The algorithms to extract the tomography are proposed. Two applications of multilayer information retrieval and 3D object imaging using full-field OCT are described.

  12. Profile and Determinants of Retinal Optical Intensity in Normal Eyes with Spectral Domain Optical Coherence Tomography.

    Directory of Open Access Journals (Sweden)

    Binyao Chen

    Full Text Available To investigate the profile and determinants of retinal optical intensity in normal subjects using 3D spectral domain optical coherence tomography (SD OCT.A total of 231 eyes from 231 healthy subjects ranging in age from 18 to 80 years were included and underwent a 3D OCT scan. Forty-four eyes were randomly chosen to be scanned by two operators for reproducibility analysis. Distribution of optical intensity of each layer and regions specified by the Early Treatment of Diabetic Retinopathy Study (ETDRS were investigated by analyzing the OCT raw data with our automatic graph-based algorithm. Univariate and multivariate analyses were performed between retinal optical intensity and sex, age, height, weight, spherical equivalent (SE, axial length, image quality, disc area and rim/disc area ratio (R/D area ratio.For optical intensity measurements, the intraclass correlation coefficient of each layer ranged from 0.815 to 0.941, indicating good reproducibility. Optical intensity was lowest in the central area of retinal nerve fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer and photoreceptor layer, except for the retinal pigment epithelium (RPE. Optical intensity was positively correlated with image quality in all retinal layers (0.5530.05. There was no relationship between retinal optical intensity and sex, height, weight, SE, axial length, disc area and R/D area ratio.There was a specific pattern of distribution of retinal optical intensity in different regions. The optical intensity was affected by image quality and age. Image quality can be used as a reference for normalization. The effect of age needs to be taken into consideration when using OCT for diagnosis.

  13. Ultrafast coherent dynamics of a photonic crystal all-optical switch

    CERN Document Server

    Colman, Pierre; Yu, Yi; Mørk, Jesper


    We present pump-probe measurements of an all-optical photonic crystal switch based on a nanocavity, resolving fast coherent temporal dynamics. The measurements demonstrate the importance of coherent effects typically neglected when considering nanocavity dynamics. In particular, we report the observation of an idler pulse. The measurements are in good agreement with a theoretical model that allows us to ascribe the observation to oscillations of the free carrier population in the nanocavity. The effect opens perspectives for the realization of new all-optical photonic crystal switches with unprecedented switching contrast.

  14. Digital coherent receiver for phase modulated radio-over-fibre optical links

    DEFF Research Database (Denmark)

    Zibar, Darko; Yu, Xianbin; Peucheret, Christophe


    A novel digital signal processing-based coherent receiver for phase-modulated radio-over-fiber (RoF) optical links is presented and demonstrated experimentally. Error-free demodulation of 50-Mbaud binary phase-shift keying (BPSK) and quadrature phase-shift keying data signal modulated on a 5-GHz...... radio-frequency (RF) carrier is experimentally demonstrated using the proposed digital coherent receiver. Additionally, a wavelength-division-multiplexing (WDM) phase-modulated RoF optical link is experimentally demonstrated. A 3 x50 Mb/s WDM transmission of a BPSK modulated 5-GHz RF carrier is achieved...

  15. Joint phase noise and frequency offset estimation and mitigation for optically coherent QAM based on adaptive multi-symbol delay detection (MSDD). (United States)

    Tselniker, Igor; Sigron, Netta; Nazarathy, Moshe


    This paper extends our prior coherent MSDD Carrier Recovery system from QPSK to QAM operation and also characterizes for the first time the Carrier Frequency Offset (CFO) mitigation capabilities of the novel MSDD for QAM systems. We introduce and numerically investigate the performance of an improved MSDD carrier recovery system (differing from the one disclosed in our MSDD for QPSK prior paper), automatically adapting to the channel statistics for optimal phase-noise mitigation. Remarkably, we do not require a separate structure to estimate and mitigate CFO, but the same adaptive structure originally intended for phase noise mitigation is shown to also automatically provide frequency offset estimation and recovery functionality. The CFO capture range of our system is in principle infinite, whereas prior CFO mitigation systems have CFO capture ranges limited to a small a fraction of the baud-rate. When used for 16-QAM with coherent-grade lasers of 100 KHz linewidth, our MSDD system attains the best tradeoffs between performance and complexity, relative to other carrier recovery systems combining blind-phase-search with maximum likelihood detection. We also present additional MSDD phase-noise recovery system variants whereby substantially reduced complexity is traded off for slightly degraded performance. Our MSDD system is able to switch "on-the-fly" to various m-QAM constellation sizes, e.g. seamlessly transition between 16-QAM and QPSK, which may be useful for dynamically adaptive optical networks.

  16. Coherent DWDM technology for high speed optical communications (United States)

    Saunders, Ross


    The introduction of coherent digital optical transmission enables a new generation of high speed optical data transport and fiber impairment mitigation. An initial implementation of 40 Gb/s coherent systems using Dual Polarization Quadrature Phase Shift Keying (DP-QPSK) is already being installed in carrier networks. New systems running at 100 Gb/s DP-QPSK data rate are in development and early technology lab and field trial phase. Significant investment in the 100 Gb/s ecosystem (optical components, ASICs, transponders and systems) bodes well for commercial application in 2012 and beyond. Following in the footsteps of other telecommunications fields such as wireless and DSL, we can expect coherent optical transmission to evolve from QPSK to higher order modulations schemes such as Mary PSK and/or QAM. This will be an interesting area of research in coming years and poses significant challenges in terms of electro-optic, DSP, ADC/DAC design and fiber nonlinearity mitigation to reach practical implementation ready for real network deployments.

  17. Optical phase estimation via coherent state and displaced photon counting

    CERN Document Server

    Izumi, Shuro; Wakui, Kentaro; Fujiwara, Mikio; Ema, Kazuhiro; Sasaki, Masahide


    We consider the phase sensing via weak optical coherent state at quantum limit precision. A new detection scheme for the phase estimation is proposed which is inspired by the suboptimal quantum measurement in coherent optical communication. We theoretically analyze a performance of our detection scheme, which we call the displaced-photon counting, for phase sensing in terms of the Fisher information and show that the displaced-photon counting outperforms the static homodyne and heterodyne detections in wide range of the target phase. The proof-of-principle experiment is performed with linear optics and a superconducting nanowire single photon detector. The result shows that our scheme overcomes the limit of the ideal homodyne measurement even under practical imperfections.

  18. Investigating biofilm structure developing on carriers from lab-scale moving bed biofilm reactors based on light microscopy and optical coherence tomography. (United States)

    Li, Chunyan; Felz, Simon; Wagner, Michael; Lackner, Susanne; Horn, Harald


    This study focused on characterizing the structure of biofilms developed on carriers used in lab-scale moving bed biofilm reactors. Both light microscopy (2D) and optical coherence tomography (OCT) were employed to track the biofilm development on carriers of different geometry and under different aeration rates. Biofilm structure was further characterized with respect to average biofilm thickness, biofilm growth velocity, biomass volume, compartment filling degree, surface area, etc. The results showed that carriers with a smaller compartment size stimulated a quick establishment of biofilms. Low aeration rates favored fast development of biofilms. Comparison between the results derived from 2D and 3D images revealed comparable results with respect to average biofilm thickness and compartment filling degree before the carrier compartments were fully willed with biomass. However, 3D imaging with OCT was capable of visualizing and quantifying the heterogeneous structure of biofilms, which cannot be achieved using 2D imaging.

  19. Polarization-Sensitive Quantum Optical Coherence Tomography: Experiment

    CERN Document Server

    Booth, Mark C; Teich, Malvin Carl


    Polarization-sensitive quantum optical coherence tomography (PS-QOCT) makes use of a Type-II twin-photon light source for carrying out optical sectioning with polarization sensitivity. A BBO nonlinear optical crystal pumped by a Ti:sapphire psec-pulsed laser is used to confirm the theoretical underpinnings of this imaging paradigm. PS-QOCT offers even-order dispersion cancellation with simultaneous access to the group-velocity dispersion characteristics of the interstitial medium between the reflecting surfaces of the sample.

  20. Optical Coherence Tomography to Assess Neurodegeneration in Multiple Sclerosis. (United States)

    Petzold, Axel


    Retinal spectral domain optical coherence tomography (OCT) has emerged as a clinical and research tool in multiple sclerosis (MS) and optic neuritis (ON). This chapter summarizes a short OCT protocol as included in international consensus guidelines. The protocol was written for hands-on style such that both clinicians and OCT technicians can make use of it. The protocol is suitable for imaging of the optic nerve head and macular regions as a baseline for follow-up investigations, individual layer segmentation, and diagnostic assessment.

  1. All-Optical Formation of Coherent Dark States of Silicon-Vacancy Spins in Diamond (United States)

    Pingault, Benjamin; Becker, Jonas N.; Schulte, Carsten H. H.; Arend, Carsten; Hepp, Christian; Godde, Tillmann; Tartakovskii, Alexander I.; Markham, Matthew; Becher, Christoph; Atatüre, Mete


    Spin impurities in diamond can be versatile tools for a wide range of solid-state-based quantum technologies, but finding spin impurities that offer sufficient quality in both photonic and spin properties remains a challenge for this pursuit. The silicon-vacancy center has recently attracted much interest because of its spin-accessible optical transitions and the quality of its optical spectrum. Complementing these properties, spin coherence is essential for the suitability of this center as a spin-photon quantum interface. Here, we report all-optical generation of coherent superpositions of spin states in the ground state of a negatively charged silicon-vacancy center using coherent population trapping. Our measurements reveal a characteristic spin coherence time, T2* , exceeding 45 nanoseconds at 4 K. We further investigate the role of phonon-mediated coupling between orbital states as a source of irreversible decoherence. Our results indicate the feasibility of all-optical coherent control of silicon-vacancy spins using ultrafast laser pulses.

  2. Optical clearing of melanoma in vivo: characterization by diffuse reflectance spectroscopy and optical coherence tomography (United States)

    Pires, Layla; Demidov, Valentin; Vitkin, I. Alex; Bagnato, Vanderlei; Kurachi, Cristina; Wilson, Brian C.


    Melanoma is the most aggressive type of skin cancer, with significant risk of fatality. Due to its pigmentation, light-based imaging and treatment techniques are limited to near the tumor surface, which is inadequate, for example, to evaluate the microvascular density that is associated with prognosis. White-light diffuse reflectance spectroscopy (DRS) and near-infrared optical coherence tomography (OCT) were used to evaluate the effect of a topically applied optical clearing agent (OCA) in melanoma in vivo and to image the microvascular network. DRS was performed using a contact fiber optic probe in the range from 450 to 650 nm. OCT imaging was performed using a swept-source system at 1310 nm. The OCT image data were processed using speckle variance and depth-encoded algorithms. Diffuse reflectance signals decreased with clearing, dropping by ˜90% after 45 min. OCT was able to image the microvasculature in the pigmented melanoma tissue with good spatial resolution up to a depth of ˜300 μm without the use of OCA; improved contrast resolution was achieved with optical clearing to a depth of ˜750 μm in tumor. These findings are relevant to potential clinical applications in melanoma, such as assessing prognosis and treatment responses. Optical clearing may also facilitate the use of light-based treatments such as photodynamic therapy.

  3. Optical coherence tomography complemented by hyperspectral imaging for the study of protective wood coatings

    NARCIS (Netherlands)

    Dingemans, L.M.; Papadakis, V.; Liu, P.; Adam, A.J.L.; Groves, R.M.


    Optical coherence tomography (OCT) is a contactless and non-destructive testing (NDT) technique based on lowcoherence interferometry. It has recently become a popular NDT-tool for evaluating cultural heritage. In this study, protective coatings on wood and their penetration into the wood structure w

  4. Temporal analysis of the coherent properties of optical images of rough nonplanar objects

    NARCIS (Netherlands)

    Mandrosov, V. I.


    The possibility of using temporal analysis to find the relation between chromatic properties of probe radiation and coherent properties of the optical images of rough non-planar objects is substantiated. The analysis is based on the use of the time correlation function and on the study of the speckl

  5. Simultaneous dual wavelength eye-tracked ultrahigh resolution retinal and choroidal optical coherence tomography

    DEFF Research Database (Denmark)

    Unterhuber, A.; Povaay, B.; Müller, André;


    We demonstrate an optical coherence tomography device that simultaneously combines different novel ultrabroad bandwidth light sources centered in the 800 and 1060 nm regions, operating at 66 kHz depth scan rate, and a confocal laser scanning ophthalmoscope-based eye tracker to permit motion-artif...

  6. Complete Two-dimensional Muellermetric Imaging of Biological Tissue Using Heterodyned Optical Coherence Tomography

    CERN Document Server

    Liu, Xue; Shahriar, M S


    A polarization-sensitive optical coherence tomography system based on heterodyning and filtering techniques is built to perform Stokesmetric imaging of different layers of depths in a porcine tendon sample. The complete 4\\times4 backscattering Muellermetric images of one layer are acquired using such a system. The images reveal information indiscernible from a conventional OCT system.

  7. Editorial . Quantum fluctuations and coherence in optical and atomic structures (United States)

    Eschner, Jürgen; Gatti, Alessandra; Maître, Agnès; Morigi, Giovanna


    From simple interference fringes, over molecular wave packets, to nonlinear optical patterns - the fundamental interaction between light and matter leads to the formation of structures in many areas of atomic and optical physics. Sophisticated technology in experimental quantum optics, as well as modern computational tools available to theorists, have led to spectacular achievements in the investigation of quantum structures. This special issue is dedicated to recent developments in this area. It presents a selection of examples where quantum dynamics, fluctuations, and coherence generate structures in time or in space or where such structures are observed experimentally. The examples range from coherence phenomena in condensed matter, over atoms in optical structures, entanglement in light and matter, to quantum patterns in nonlinear optics and quantum imaging. The combination of such seemingly diverse subjects formed the basis of a successful European TMR network, "Quantum Structures" (visit This special issue partly re.ects the results and collaborations of the network, going however well beyond its scope by including contributions from a global community and from many related topics which were not addressed directly in the network. The aim of this issue is to present side by side these di.erent topics, all of which are loosely summarized under quantum structures, to highlight their common aspects, their di.erences, and the progress which resulted from the mutual exchange of results, methods, and knowledge. To guide the reader, we have organized the articles into subsections which follow a rough division into structures in material systems and structures in optical .elds. Nevertheless, in the following introduction we point out connections between the contributions which go beyond these usual criteria, thus highlighting the truly interdisciplinary nature of quantum structures. Much of the progress in atom optics

  8. A proposed fibre optic time domain optical coherence tomography system using a micro-photonic stationary optical delay line (United States)

    Jansz, Paul Vernon; Wild, Graham; Hinckley, Steven


    Conventional time domain Optical Coherence Tomography (OCT) relies on a reference Optical Delay Line (ODL). These reference ODLs require the physical movement of a mirror to scan a given depth range. This movement results in instrument degradation. We propose a new optical fibre based time domain OCT system that makes use of a micro-photonic structure as a stationary ODL. The proposed system uses an in-fibre interferometer, either a Michelson or a Mach-Zhender. The reference ODL makes use of a collimator to expand the light from the optical fibre. This is them expanded in one dimension via planar optics, that is, a cylindrical lens based telescope, using a concave and convex lens. The expanded beam is them passed through a transmissive Spatial Light Modulator (SLM), specifically a liquid crystal light valve used as an optical switch. Light is then reflected back through the system off the micro-photonic structure. The micro-photonic structure is a one dimensional array of stagged mirror steps, called a Stepped Mirror Structure (SMS). The system enables the selection of discrete optical delay lengths. The proposed ODL is capable of depth hoping and multicasting. We discuss the fabrication of the SMS, which consists of eight steps, each approximately 150 μm high. A change in notch frequency using an in-fibre Mach Zhender interferometer was used to gauge the average step height. The results gave an average step height of 146 μm.

  9. Field Theory for Coherent Optical Pulse Propagation

    CERN Document Server

    Park, Q H


    We introduce a new notion of "matrix potential" to nonlinear optical systems. In terms of a matrix potential $g$, we present a gauge field theoretic formulation of the Maxwell-Bloch equation that provides a semiclassical description of the propagation of optical pulses through resonant multi-level media. We show that the Bloch part of the equation can solved identically through $g$ and the remaining Maxwell equation becomes a second order differential equation with reduced set of variables due to the gauge invariance of the system. Our formulation clarifies the (nonabelian) symmetry structure of the Maxwell-Bloch equations for various multi-level media in association with symmetric spaces $G/H$. In particular, we associate nondegenerate two-level system for self-induced transparency with $G/H=SU(2)/U(1)$ and three-level $\\L $- or V-systems with $G/H = SU(3)/U(2)$. We give a detailed analysis for the two-level case in the matrix potential formalism, and address various new properties of the system including so...

  10. Optical coherence tomography: Monte Carlo simulation and improvement by optical amplification

    DEFF Research Database (Denmark)

    Tycho, Andreas


    An advanced novel Monte Carlo simulation model of the detection process of an optical coherence tomography (OCT) system is presented. For the first time it is shown analytically that the applicability of the incoherent Monte Carlo approach to model the heterodyne detection process of an OCT system...... model of the OCT signal. The OCT signal from a scattering medium are obtained for several beam and sample geometries using the new Monte Carlo model, and when comparing to results of an analytical model based on the extended Huygens-Fresnel principle excellent agreement is obtained. With the greater...... flexibility of Monte Carlo simulations, this new model is demonstrated to be excellent as a numerical phantom, i.e., as a substitute for otherwise difficult experiments. Finally, a new model of the signal-to-noise ratio (SNR) of an OCT system with optical amplification of the light reflected from the sample...

  11. Optical Coherence Tomography in Pulmonary Medicine (United States)

    Murgu, Septimiu Dan; Brenner, Matthew; Chen, Zhongping; Suter, Melissa J.

    Advances in pulmonary diagnostics and therapeutics offer a major potential for optical imaging applications both in clinical practice and research settings. Complexities of pulmonary structures and function have restricted widespread OCT investigations and clinical applications, but these will likely be overcome by developments in OCT technology [1]. Some factors that have limited adaptation of OCT into the pulmonary setting in the past have been the shallow depth of penetration, resolution limitations, relatively slow access times, need to examine large surface areas with numerous branching airways, motion artifacts, as well as a need for development of practical imaging probes to reach the relevant locations in a minimally invasive way. Considerable recent engineering and analytical advances in OCT technology [2-8] have already overcome several of these obstacles and will enable much more extensive investigations into the role for structural and functional pulmonary OCT imaging [1].

  12. Evaluation of fingerprint deformation using optical coherence tomography (United States)

    Gutierrez da Costa, Henrique S.; Maxey, Jessica R.; Silva, Luciano; Ellerbee, Audrey K.


    Biometric identification systems have important applications to privacy and security. The most widely used of these, print identification, is based on imaging patterns present in the fingers, hands and feet that are formed by the ridges, valleys and pores of the skin. Most modern print sensors acquire images of the finger when pressed against a sensor surface. Unfortunately, this pressure may result in deformations, characterized by changes in the sizes and relative distances of the print patterns, and such changes have been shown to negatively affect the performance of fingerprint identification algorithms. Optical coherence tomography (OCT) is a novel imaging technique that is capable of imaging the subsurface of biological tissue. Hence, OCT may be used to obtain images of subdermal skin structures from which one can extract an internal fingerprint. The internal fingerprint is very similar in structure to the commonly used external fingerprint and is of increasing interest in investigations of identify fraud. We proposed and tested metrics based on measurements calculated from external and internal fingerprints to evaluate the amount of deformation of the skin. Such metrics were used to test hypotheses about the differences of deformation between the internal and external images, variations with the type of finger and location inside the fingerprint.

  13. Frobenius-norm-based measures of quantum coherence and asymmetry. (United States)

    Yao, Yao; Dong, G H; Xiao, Xing; Sun, C P


    We formulate the Frobenius-norm-based measures for quantum coherence and asymmetry respectively. In contrast to the resource theory of coherence and asymmetry, we construct a natural measure of quantum coherence inspired from optical coherence theory while the group theoretical approach is employed to quantify the asymmetry of quantum states. Besides their simple structures and explicit physical meanings, we observe that these quantities are intimately related to the purity (or linear entropy) of the corresponding quantum states. Remarkably, we demonstrate that the proposed coherence quantifier is not only a measure of mixedness, but also an intrinsic (basis-independent) quantification of quantum coherence contained in quantum states, which can also be viewed as a normalized version of Brukner-Zeilinger invariant information. In our context, the asymmetry of N-qubit quantum systems is considered under local independent and collective transformations. In- triguingly, it is illustrated that the collective effect has a significant impact on the asymmetry measure, and quantum correlation between subsystems plays a non-negligible role in this circumstance.

  14. Frobenius-norm-based measures of quantum coherence and asymmetry (United States)

    Yao, Yao; Dong, G. H.; Xiao, Xing; Sun, C. P.


    We formulate the Frobenius-norm-based measures for quantum coherence and asymmetry respectively. In contrast to the resource theory of coherence and asymmetry, we construct a natural measure of quantum coherence inspired from optical coherence theory while the group theoretical approach is employed to quantify the asymmetry of quantum states. Besides their simple structures and explicit physical meanings, we observe that these quantities are intimately related to the purity (or linear entropy) of the corresponding quantum states. Remarkably, we demonstrate that the proposed coherence quantifier is not only a measure of mixedness, but also an intrinsic (basis-independent) quantification of quantum coherence contained in quantum states, which can also be viewed as a normalized version of Brukner-Zeilinger invariant information. In our context, the asymmetry of N-qubit quantum systems is considered under local independent and collective transformations. In- triguingly, it is illustrated that the collective effect has a significant impact on the asymmetry measure, and quantum correlation between subsystems plays a non-negligible role in this circumstance.

  15. All fiber optics circular-state swept source polarization-sensitive optical coherence tomography. (United States)

    Lin, Hermann; Kao, Meng-Chun; Lai, Chih-Ming; Huang, Jyun-Cin; Kuo, Wen-Chuan


    A swept source (SS)-based circular-state (CS) polarization-sensitive optical coherence tomography (PS-OCT) constructed entirely with polarization-maintaining fiber optics components is proposed with the experimental verification. By means of the proposed calibration scheme, bulk quarter-wave plates can be replaced by fiber optics polarization controllers to, therefore, realize an all-fiber optics CS SSPS-OCT. We also present a numerical dispersion compensation method, which can not only enhance the axial resolution, but also improve the signal-to-noise ratio of the images. We demonstrate that this compact and portable CS SSPS-OCT system with an accuracy comparable to bulk optics systems requires less stringent lens alignment and can possibly serve as a technology to realize PS-OCT instrument for clinical applications (e.g., endoscopy). The largest deviations in the phase retardation (PR) and fast-axis (FA) angle due to sample probe in the linear scanning and a rotation angle smaller than 65 deg were of the same order as those in stationary probe setups. The influence of fiber bending on the measured PR and FA is also investigated. The largest deviations of the PR were 3.5 deg and the measured FA change by ~12 to 21 deg. Finally, in vivo imaging of the human fingertip and nail was successfully demonstrated with a linear scanning probe.

  16. Optical coherence tomography a clinical and technical update

    CERN Document Server

    Cunha-Vaz, José


    Optical Coherence Tomography represents the ultimate noninvasive  ocular imaging technique although being in the field for over two-decades. This book encompasses both medical and technical developments and recent achievements. Here, the authors cover the field of application from the anterior to the posterior ocular segments (Part I) and present a comprehensive review on the development of OCT. Important developments towards  clinical applications are covered in Part II, ranging from the adaptive optics to the integration on a slit-lamp, and passing through new structural  and functional information extraction from OCT data. The book is intended to be informative, coherent and comprehensive for both the medical and technical communities and aims at easing the communication between the two fields and bridging the gap between the two scientific communities.

  17. Imaging cutaneous T-Cell lymphoma with optical coherence tomography

    DEFF Research Database (Denmark)

    Ring, H.C.; Hansen Stamp, I.M.; Jemec, G.B.E.


    Aim: To investigate the presentation of a patch-stage cutaneous T-cell lymphoma (CTCL) using optical coherence tomography (OCT). Methods: A patient with a patch caused by CTCL was photographed digitally, OCT-scanned and biopsied. A normal skin area adjacent to the patch was OCT-scanned for compar......Aim: To investigate the presentation of a patch-stage cutaneous T-cell lymphoma (CTCL) using optical coherence tomography (OCT). Methods: A patient with a patch caused by CTCL was photographed digitally, OCT-scanned and biopsied. A normal skin area adjacent to the patch was OCT.......13 mm. A good immediate correlation was found between histology and OCT imaging of the sample. Conclusion: The aetiology of the elongated structures is thought to be lymphomatous infiltrates. Similar findings have been described in ocular lymphoma and may therefore be an important characteristic...

  18. Control of coherent backscattering by breaking optical reciprocity

    CERN Document Server

    Bromberg, Y; Popoff, S M; Cao, H


    Reciprocity is a universal principle that has a profound impact on many areas of physics. A fundamental phenomenon in condensed-matter physics, optical physics and acoustics, arising from reciprocity, is the constructive interference of quantum or classical waves which propagate along time-reversed paths in disordered media, leading to, for example, weak localization and metal-insulator transition. Previous studies have shown that such coherent effects are suppressed when reciprocity is broken. Here we show that by breaking reciprocity in a controlled manner, we can tune, rather than simply suppress, these phenomena. In particular, we manipulate coherent backscattering of light, also known as weak localization. By utilizing a non-reciprocal magneto-optical effect, we control the interference between time-reversed paths inside a multimode fiber with strong mode mixing, and realize a continuous transition from the well-known peak to a dip in the backscattered intensity. Our results may open new possibilities fo...

  19. Parametric imaging of viscoelasticity using optical coherence elastography (United States)

    Wijesinghe, Philip; McLaughlin, Robert A.; Sampson, David D.; Kennedy, Brendan F.


    We demonstrate imaging of soft tissue viscoelasticity using optical coherence elastography. Viscoelastic creep deformation is induced in tissue using step-like compressive loading and the resulting time-varying deformation is measured using phase-sensitive optical coherence tomography. From a series of co-located B-scans, we estimate the local strain rate as a function of time, and parameterize it using a four-parameter Kelvin-Voigt model of viscoelastic creep. The estimated viscoelastic strain and time constant are used to visualize viscoelastic creep in 2D, dual-parameter viscoelastograms. We demonstrate our technique on six silicone tissue-simulating phantoms spanning a range of viscoelastic parameters. As an example in soft tissue, we report viscoelastic contrast between muscle and connective tissue in fresh, ex vivo rat gastrocnemius muscle and mouse abdominal transection. Imaging viscoelastic creep deformation has the potential to provide complementary contrast to existing imaging modalities, and may provide greater insight into disease pathology.

  20. Research of Mobile Radio Access Networking which Based on Optical Coherent Modulation Technique to Realize Base Station Carrier Remote via Optical Fiber%基于光学相干调制技术实现基站载波光纤拉远的无线移动接入网络研究与设计

    Institute of Scientific and Technical Information of China (English)



    分析了目前数字基带射频拉远组网架构的优势与弊端,提出了基于光学相干调制技术实现基站载波光纤拉远的无线移动接入网络架构,分析了其组网架构的优越性,给出了该接入网的具体实施方式。%In the paper,we analysed the advantages and disadvantages of the current? radio access networking architecture-dig-ital based band remote via optical fiber. We proposed a mobile radio access networking architecture which based on optical co-herent modulation technique to realize base station carrier remote via optical fiber.

  1. Efficiency analysis of homodyne detection for a coherent lidar with adaptive optics (United States)

    Liu, Wei; Wang, Liang; Yao, Kainan; Cao, Jingtai; Huang, Danian; Gu, Haijun


    For a coherent lidar, the efficiency of homodyne detection is a significant factor. Adaptive optics (AO) is an effective way to correct the turbulence-induced wavefront distortions. Based on our previous works, an expression for the homodyne detection efficiency is given. The results of the numerical simulation show that the atmospheric coherent length has an influence on the homodyne detection efficiency for a fixed atmospheric Greenwood frequency and a closed-loop control bandwidth. In addition, an experimental AO system is employed to verify the effect of the AO on the coherent lidar. The results show that the homodyne detection efficiency is obviously improved after aberrations are corrected. The conclusion of this paper provides a reference for designing an AO system for a coherent lidar.

  2. Strong electronic correlation effects in coherent multidimensional nonlinear optical spectroscopy. (United States)

    Karadimitriou, M E; Kavousanaki, E G; Dani, K M; Fromer, N A; Perakis, I E


    We discuss a many-body theory of the coherent ultrafast nonlinear optical response of systems with a strongly correlated electronic ground state that responds unadiabatically to photoexcitation. We introduce a truncation of quantum kinetic density matrix equations of motion that does not rely on an expansion in terms of the interactions and thus applies to strongly correlated systems. For this we expand in terms of the optical field, separate out contributions to the time-evolved many-body state due to correlated and uncorrelated multiple optical transitions, and use "Hubbard operator" density matrices to describe the exact dynamics of the individual contributions within a subspace of strongly coupled states, including "pure dephasing". Our purpose is to develop a quantum mechanical tool capable of exploring how, by coherently photoexciting selected modes, one can trigger nonlinear dynamics of strongly coupled degrees of freedom. Such dynamics could lead to photoinduced phase transitions. We apply our theory to the nonlinear response of a two-dimensional electron gas (2DEG) in a magnetic field. We coherently photoexcite the two lowest Landau level (LL) excitations using three time-delayed optical pulses. We identify some striking temporal and spectral features due to dynamical coupling of the two LLs facilitated by inter-Landau-level magnetoplasmon and magnetoroton excitations and compare to three-pulse four-wave-mixing (FWM) experiments. We show that these features depend sensitively on the dynamics of four-particle correlations between an electron-hole pair and a magnetoplasmon/magnetoroton, reminiscent of exciton-exciton correlations in undoped semiconductors. Our results shed light into unexplored coherent dynamics and relaxation of the quantum Hall system (QHS) and can provide new insight into non-equilibrium co-operative phenomena in strongly correlated systems.

  3. Parallel optical coherence tomography using a CCD camera

    Institute of Scientific and Technical Information of China (English)

    Junle Qu(屈军乐); Ravi S.Jonnal; Donald T. Miller


    Parallel optical coherence tomography is demonstrated using a 12-bit scientific-grade charge-coupled device array.A superluminescent diode in combination with a free-space Michelson interferometer was employed to achieve 10-μm axial resolution and 1.1-μm transverse resolution on a 902×575 μm2 field of view.We imaged a test mirror and bovine retinal tissue using a four-step phase shift method.

  4. Submicron Resolution Spectral-Domain Optical Coherence Tomography

    KAUST Repository

    Alarousu, Erkki


    Apparatuses and systems for submicron resolution spectral-domain optical coherence tomography (OCT) are disclosed. The system may use white light sources having wavelengths within 400-1000 nanometers, and achieve resolution below 1 .mu.m. The apparatus is aggregated into a unitary piece, and a user can connect the apparatus to a user provided controller and/or light source. The light source may be a supercontinuum source.

  5. The APOSTEL recommendations for reporting quantitative optical coherence tomography studies

    DEFF Research Database (Denmark)

    Cruz-Herranz, Andrés; Balk, Lisanne J; Oberwahrenbrock, Timm


    OBJECTIVE: To develop consensus recommendations for reporting of quantitative optical coherence tomography (OCT) study results. METHODS: A panel of experienced OCT researchers (including 11 neurologists, 2 ophthalmologists, and 2 neuroscientists) discussed requirements for performing and reporting...... relevant when reporting quantitative OCT studies. The areas covered are study protocol, acquisition device, acquisition settings, scanning protocol, funduscopic imaging, postacquisition data selection, postacquisition data analysis, recommended nomenclature, and statistical analysis. CONCLUSIONS...

  6. Multifocal cysticercosis with optical coherence tomography findings in a child

    Directory of Open Access Journals (Sweden)

    Manisha Agarwal


    Full Text Available We herein report a case with multifocal cysticercosis - sub-conjunctival cysticercus cyst, sub-retinal cysticercosis, and neurocysticercosis in a child. The optical coherence tomography (OCT findings of the sub-retinal cysticercus cyst are reported. He was treated with anti-helminthic drugs and oral prednisolone followed by surgical removal of the sub-retinal cyst. He subsequently underwent silicone oil removal with lens aspiration and intraocular lens implantation maintaining stable vision

  7. All-optically integrated multimodality imaging system: combined photoacoustic microscopy, optical coherence tomography, and fluorescence imaging (United States)

    Chen, Zhongjiang; Yang, Sihua; Xing, Da


    We have developed a multimodality imaging system by optically integrating all-optical photoacoustic microscopy (AOPAM), optical coherence tomography (OCT) and fluorescence microscopy (FLM) to provide complementary information including optical absorption, optical back-scattering and fluorescence contrast of biological tissue. By sharing the same low-coherence Michelson interferometer, AOPAM and OCT could be organically optically combined to obtain the absorption and scattering information of the biological tissues. Also, owing to using the same laser source and objective lens, intrinsically registered photoacoustic and fluorescence signals are obtained to present the radiative and nonradiative transition process of absorption. Simultaneously photoacoustic angiography, tissue structure and fluorescence molecular in vivo images of mouse ear were acquired to demonstrate the capabilities of the optically integrated trimodality imaging system, which can present more information to study tumor angiogenesis, vasculature, anatomical structure and microenvironments in vivo.

  8. Optical Coherence Tomography as a Tool for Ocular Dynamics Estimation

    Directory of Open Access Journals (Sweden)

    Damian Siedlecki


    Full Text Available Purpose. The aim of the study is to demonstrate that the ocular dynamics of the anterior chamber of the eye can be estimated quantitatively by means of optical coherence tomography (OCT. Methods. A commercial high speed, high resolution optical coherence tomographer was used. The sequences of tomographic images of the iridocorneal angle of three subjects were captured and each image from the sequence was processed in MATLAB environment in order to detect and identify the contours of the cornea and iris. The data on pulsatile displacements of the cornea and iris and the changes of the depth of the gap between them were retrieved from the sequences. Finally, the spectral analysis of the changes of these parameters was performed. Results. The results of the temporal and spectral analysis manifest the ocular microfluctuation that might be associated with breathing (manifested by 0.25 Hz peak in the power spectra, heart rate (1–1.5 Hz peak, and ocular hemodynamics (3.75–4.5 Hz peak. Conclusions. This paper shows that the optical coherence tomography can be used as a tool for noninvasive estimation of the ocular dynamics of the anterior segment of the eye, but its usability in diagnostics of the ocular hemodynamics needs further investigations.

  9. Imaging patients with glaucoma using spectral-domain optical coherence tomography and optical microangiography (United States)

    Auyeung, Kris; Auyeung, Kelsey; Kono, Rei; Chen, Chieh-Li; Zhang, Qinqin; Wang, Ruikang K.


    In ophthalmology, a reliable means of diagnosing glaucoma in its early stages is still an open issue. Past efforts, including forays into fluorescent angiography (FA) and early optical coherence tomography (OCT) systems, to develop a potential biomarker for the disease have been explored. However, this development has been hindered by the inability of the current techniques to provide useful depth and microvasculature information of the optic nerve head (ONH), which have been debated as possible hallmarks of glaucoma progression. We reasoned that a system incorporating a spectral-domain OCT (SD-OCT) based Optical Microangiography (OMAG) system, could allow an effective, non-invasive methodology to evaluate effects on microvasculature by glaucoma. SD-OCT follows the principle of light reflection and interference to produce detailed cross-sectional and 3D images of the eye. OMAG produces imaging contrasts via endogenous light scattering from moving particles, allowing for 3D image productions of dynamic blood perfusion at capillary-level resolution. The purpose of this study was to investigate the optic cup perfusion (flow) differences in glaucomatous and normal eyes. Images from three normal and five glaucomatous subjects were analyzed our OCT based OMAG system for blood perfusion and structural images, allowing for comparisons. Preliminary results from blood flow analysis revealed reduced blood perfusion within the whole-depth region encompassing the Lamina Cribrosa in glaucomatous cases as compared to normal ones. We conclude that our OCT-OMAG system may provide promise and viability for glaucoma screening.

  10. Three-dimensional multifunctional optical coherence tomography for skin imaging (United States)

    Li, En; Makita, Shuichi; Hong, Young-Joo; Kasaragod, Deepa; Sasaoka, Tomoko; Yamanari, Masahiro; Sugiyama, Satoshi; Yasuno, Yoshiaki


    Optical coherence tomography (OCT) visualizes cross-sectional microstructures of biological tissues. Recent developments of multifunctional OCT (MF-OCT) provides multiple optical contrasts which can reveal currently unknown tissue properties. In this contribution we demonstrate multifunctional OCT specially designed for dermatological investigation. And by utilizing it to measure four different body parts of in vivo human skin, three-dimensional scattering OCT, OCT angiography, polarization uniformity tomography, and local birefringence tomography images were obtained by a single scan. They respectively contrast the structure and morphology, vasculature, melanin content and collagen traits of the tissue.

  11. High efficiency coherent beam combining of semiconductor optical amplifiers. (United States)

    Creedon, Kevin J; Redmond, Shawn M; Smith, Gary M; Missaggia, Leo J; Connors, Michael K; Kansky, Jan E; Fan, Tso Yee; Turner, George W; Sanchez-Rubio, Antonio


    We demonstrate 40 W coherently combined output power in a single diffraction-limited beam from a one-dimensional 47-element array of angled-facet slab-coupled optical waveguide amplifiers at 1064 nm. The output from each emitter was collimated and overlapped onto a diffractive optical element combiner using a common transform lens. Phase locking was achieved via active feedback on each amplifier's drive current to maximize the power in the combined beam. The combining efficiency at all current levels was nearly constant at 87%.

  12. Modeling light–tissue interaction in optical coherence tomography systems

    DEFF Research Database (Denmark)

    Andersen, Peter E.; Jørgensen, Thomas Martini; Thrane, Lars


    Optical coherence tomography (OCT) performs high-resolution, cross-sectional tomographic imaging of the internal tissue microstructure by measuring backscattered or backreflected light. The scope of this chapter is to present analytical and numerical models that are able to describe light......-tissue interactions and its influence on the performance of OCT systems including multiple scattering effects in heterogeneous media. In general, these models, analytical as well as numerical, may serve as important tools for improving interpretation of OCT images and also serve as prerequisites for extraction...... of tissue optical scattering parameters....

  13. The diagnosis of nasopharyngeal carcinoma by optical coherence tomography (OCT) (United States)

    Li, J. H.; Du, Y.


    We have attempted to explore the intrinsic differences in the optical properties of the nasopharyngeal carcinoma (NPC) and normal tissue by optical coherence tomography (OCT). OCT imaging of normal tissue provided three layers of epithelium, lamina propria, and the brighter interface of basement membrane; while carcinomas disrupted the layered construction embedded in signal-poor images. The morphologies were consistent with histological findings. Sensitivity and specificity were 90% and 100%, respectively. This pilot study demonstrates that NPC could be diagnosed by visualization, which implies that OCT might be potentially used to differentiate normal from NPC tissue in the early stage as an invasive biopsy.

  14. Quantum theory of optical coherence selected papers and lectures

    CERN Document Server

    Glauber, Roy J


    A summary of the pioneering work of Glauber in the field of optical coherence phenomena and photon statistics, this book describes the fundamental ideas of modern quantum optics and photonics in a tutorial style. It is thus not only intended as a reference for researchers in the field, but also to give graduate students an insight into the basic theories of the field. Written by the Nobel Laureate himself, the concepts described in this book have formed the basis for three further Nobel Prizes in Physics within the last decade

  15. Variable-time-delay optical coherent transient signal processing. (United States)

    Merkel, K D; Babbitt, W R; Anderson, K E; Wagner, K H


    A technique is proposed and experimentally demonstrated that achieves simultaneous optical pattern waveform storage and programmable time delay for continuous real-time signal processing by use of optical coherent transient technology. We achieve variable-time-delay and broadband signal processing by frequency shifting of two chirped programming pulses, the chirp rate of one being twice that of the other, without using brief reference pulses and without changing the timing of the programming sequence. We demonstrate the technique experimentally in Tm(3+): YAG at 5 K for 40-MHz chirps by performing temporal signal convolution with true-time delays that vary over a 250-ns range.

  16. Storage and recall of weak coherent optical pulses with an efficiency of 25%

    CERN Document Server

    Sabooni, M; Walther, A; Lin, N; Amari, A; Huang, M; Kröll, S


    We demonstrate experimentally a quantum memory scheme for the storage of weak coherent light pulses in an inhomogeneously broadened optical transition in a Pr^{3+}: YSO crystal at 2.1 K. Precise optical pumping using a frequency stable (about 1kHz linewidth) laser is employed to create a highly controllable Atomic Frequency Comb (AFC) structure. We report single photon storage and retrieval efficiencies of 25%, based on coherent photon echo type re-emission in the forward direction. The coherence property of the quantum memory is proved through interference between a super Gaussian pulse and the emitted echo. Backward retrieval of the photon echo emission has potential for increasing storage and recall efficiency.

  17. Surface imaging of metallic material fractures using optical coherence tomography. (United States)

    Hutiu, Gheorghe; Duma, Virgil-Florin; Demian, Dorin; Bradu, Adrian; Podoleanu, Adrian Gh


    We demonstrate the capability of optical coherence tomography (OCT) to perform topography of metallic surfaces after being subjected to ductile or brittle fracturing. Two steel samples, OL 37 and OL 52, and an antifriction Sn-Sb-Cu alloy were analyzed. Using an in-house-built swept source OCT system, height profiles were generated for the surfaces of the two samples. Based on such profiles, it can be concluded that the first two samples were subjected to ductile fracture, while the third one was subjected to brittle fracture. The OCT potential for assessing the surface state of materials after fracture was evaluated by comparing OCT images with images generated using an established method for such investigations, scanning electron microscopy (SEM). Analysis of cause of fracture is essential in response to damage of machinery parts during various accidents. Currently the analysis is performed using SEM, on samples removed from the metallic parts, while OCT would allow in situ imaging using mobile units. To the best of our knowledge, this is the first time that the OCT capability to replace SEM has been demonstrated. SEM is a more costly and time-consuming method to use in the investigation of surfaces of microstructures of metallic materials.

  18. Clinical use of optical coherence tomography and fractional flow reserve

    Directory of Open Access Journals (Sweden)

    Ivanović Vladimir


    Full Text Available Introduction. The aim of each diagnostic method is to serve as a guide in deciding about the right patient treatment. During myocardial revascularization the decision to perform revascularization is usually not easy to make, especially in case of borderline stenosis. It has been proven that it is not enough to base morphological evaluation of coronary artery vessel stenosis solely on angiography. It is necessary to include additional modern diagnostic methods for functional analysis and detailed morphological analysis using fractional flow reserve (FFR and optical coherence tomography (OCT, respectively. Case reports. In the first case report we showed the significance of morphological analysis using OCT and proved that it was not lumen stenosis. The second and the third case reports showed the complementarity between functional analysis (FFR and morphological analysis (OCT of stenosis in solving a complex coronary disease. The fourth case report showed the significance of OCT in dealing with the recurrent stent restenosis. Conclusion. By these short case reports we confirmed that percutaneous coronary intervention (PCI guided by angiography is definitely not enough in deciding about myocardial revascularization especially in patients with a complex coronary disease. In certain cases FFR and OCT procedures can be complementary methods and improve quality of revascularization, particularly in the case of recurrent in-stent restenosis.

  19. Optical coherence tomography-guided classification of epiretinal membranes. (United States)

    Konidaris, Vasileios; Androudi, Sofia; Alexandridis, Alexandros; Dastiridou, Anna; Brazitikos, Periklis


    To study and classify epiretinal membranes (ERMs) based on spectral domain optical coherence tomography (SD-OCT) findings. One hundred and twelve patients with ERMs were examined clinically and underwent OCT examination. The anatomical structure of the macula and vitreoretinal interface was studied. ERMs were classified in two categories: A, with posterior vitreous detachment (PVD) (91 cases), and B, with the absence of PVD (21 cases). Category A was divided into two subcategories: A1, without contraction of the ERM (37 cases), and A2, with the presence of membrane contraction (54 cases). A2 was further subdivided into A2.1, with retinal folding (15 cases), A2.2, with edema (23 cases), A2.3, with cystoid macular edema (9 cases), and A2.4, with lamellar macular hole (7 cases). Category B was divided in two subcategories: B1, without vitreomacular traction (VMT) (4 cases), and B2, with the presence of VMT (17 cases). Category B2 was subdivided into B2.1, with edema (9 cases), B2.2, presenting retinal detachment (5 cases), and B2.3, with schisis (3 cases). OCT classification of ERMs provides useful information on the anatomical structure of the retina, and the accurate estimation of vitreoretinal interface.

  20. Novel adaptive fiber-optics collimator for coherent beam combination. (United States)

    Zhi, Dong; Ma, Pengfei; Ma, Yanxing; Wang, Xiaolin; Zhou, Pu; Si, Lei


    In this manuscript, we experimentally validate a novel design of adaptive fiber-optics collimator (AFOC), which utilizes two levers to enlarge the movable range of the fiber end cap. The enlargement of the range makes the new AFOC possible to compensate the end-cap/tilt aberration in fiber laser beam combining system. The new AFOC based on flexible hinges and levers was fabricated and the performance of the new AFOC was tested carefully, including its control range, frequency response and control accuracy. Coherent beam combination (CBC) of two 5-W fiber amplifiers array with simultaneously end-cap/tilt control and phase-locking control was implemented successfully with the novel AFOC. Experimental results show that the average normalized power in the bucket (PIB) value increases from 0.311 to 0.934 with active phasing and tilt aberration compensation simultaneously, and with both controls on, the fringe contrast improves to more than 82% from 0% for the case with both control off. This work presents a promising structure for tilt aberration control in high power CBC system.

  1. Polarization sensitive spectroscopic optical coherence tomography for multimodal imaging (United States)

    Strąkowski, Marcin R.; Kraszewski, Maciej; Strąkowska, Paulina; Trojanowski, Michał


    Optical coherence tomography (OCT) is a non-invasive method for 3D and cross-sectional imaging of biological and non-biological objects. The OCT measurements are provided in non-contact and absolutely safe way for the tested sample. Nowadays, the OCT is widely applied in medical diagnosis especially in ophthalmology, as well as dermatology, oncology and many more. Despite of great progress in OCT measurements there are still a vast number of issues like tissue recognition or imaging contrast enhancement that have not been solved yet. Here we are going to present the polarization sensitive spectroscopic OCT system (PS-SOCT). The PS-SOCT combines the polarization sensitive analysis with time-frequency analysis. Unlike standard polarization sensitive OCT the PS-SOCT delivers spectral information about measured quantities e.g. tested object birefringence changes over the light spectra. This solution overcomes the limits of polarization sensitive analysis applied in standard PS-OCT. Based on spectral data obtained from PS-SOCT the exact value of birefringence can be calculated even for the objects that provide higher order of retardation. In this contribution the benefits of using the combination of time-frequency and polarization sensitive analysis are being expressed. Moreover, the PS-SOCT system features, as well as OCT measurement examples are presented.

  2. Coherent Light induced in Optical Fiber by a Charged Particle (United States)

    Artru, Xavier; Ray, Cédric


    Coherent light production in an optical fiber by a charged particle (named PIGL, for particle-induced guided, light) is reviewed. From the microscopic point of view, light is emitted by transient electric dipoles induced in the fiber medium by the Coulomb field of the particle. The phenomenon can also considered as the capture of virtual photons of the particle field by the fiber. Two types of captures are distinguished. Type-I takes place in a uniform part of the fiber; then the photon keeps its longitudinal momentum pz . Type-II takes place near an end or in a non-uniform part of the fiber; then pz is not conserved. Type-I PIGL is not affected by background lights external to the fiber. At grazing incidence it becomes nearly monochromatic. Its circular polarization depends on the angular momentum of the particle about the fiber and on the relative velocity between the particle and the guided wave. A general formula for the yield of Type-II radiation, based on the reciprocity theorem, is proposed. This radiation can be assisted by metallic objects stuck to the fiber, via plasmon excitation. A periodic structure leads to a guided Smith-Purcell radiation. Applications of PIGL in beam diagnostics are considered.

  3. Asynchronously sampled blind source separation for coherent optical links (United States)

    Detwiler, Thomas F.; Searcy, Steven M.; Stark, Andrew J.; Ralph, Stephen E.; Basch, Bert E.


    Polarization multiplexing is an integral technique for generating spectrally efficient 100 Gb/s and higher optical links. Post coherent detection DSP-based polarization demultiplexing of QPSK links is commonly performed after timing recovery. We propose and demonstrate a method of asynchronous blind source separation using the constant modulus algorithm (CMA) on the asynchronously sampled signal to initially separate energy from arbitrarily aligned polarization states. This method lends well to implementation as it allows for an open-loop sampling frequency for analog-to-digital conversion at less than twice the symbol rate. We show that the performance of subsequent receiver functions is enhanced by the initial pol demux operation. CMA singularity behavior is avoided through tap settling constraints. The method is applicable to QPSK transmissions and many other modulation formats as well, including general QAM signals, offset-QPSK, and CPM, or a combination thereof. We present the architecture and its performance under several different formats and link conditions. Comparisons of complexity and performance are drawn between the proposed architecture and conventional receivers.

  4. Optic Coherence Tomography of Idiopathic Macular Epiretinal Membranes

    Institute of Scientific and Technical Information of China (English)

    Xing Liu; Yunlan Ling; Jingjing Huang; Xiaoping Zheng


    bjectives: To study the characteristics of optical coherence tomography (OCT)inopathic macular epiretinal membranes (IMEM) and the relationship between thethickness offovea and the vision of affected eyes.Methods:A total of 67 cases (73 eyes) with clinical diagnosis of IMEM using direct,indirect ophthalmoscope, three mirror contact lens, fundus color photography or fundusfluorescein angiography (FFA)were examined with OCTResults: Epiretinal membranes (ERMs) with macular edema were found in 32 eyes,proliferative ERMs in 20 eyes, ERMs with macular pseudoholes in 14 eyes and ERMswith laminar macular holes in 7 eyes. Based on OCT, the ERMs were clearly andpartially seperated from the retinal (27 eyes, 38.36% ), the retinal thickness of thefovea was the thickest in the proliferative ERMs and the thinnest in the ERMs withlaminar macular holes. The statistical analysis showed there was a negative correlationbetween the thickness of fovea and visual acuity ( r = - 0. 454, P = 0. 000).Conclusion:There were four types of images of OCT in IMEM: ERMs with macularedema, proliferative ERMs, ERMs with macular pseudohole and ERMs with laminarmacular hole; and the thicker the fovea under the OCT, the poorer the vision acuity in the affected eyes with ERMs.

  5. A smartphone based cardiac coherence biofeedback system. (United States)

    De Jonckheere, J; Ibarissene, I; Flocteil, M; Logier, R


    Cardiac coherence biofeedback training consist on slowing one's breathing to 0.1 Hz in order to simulate the baroreflex sensitivity and increase the respiratory sinus arrhythmia efficiency. Several studies have shown that these breathing exercises can constitute an efficient therapy in many clinical contexts like cardiovascular diseases, asthma, fibromyalgia or post-traumatic stress. Such a non-intrusive therapeutic solution needs to be performed on an 8 to 10 weeks period. Even if some heart rate variability based solutions exist, they presented some mobility constrain rendering these cardiac / respiratory control technologies more difficult to perform on a daily used. In this paper, we present a new simplified smartphone based solution allowing people to process efficient cardiac coherence biofeedback exercises. Based on photo-plethysmographic imaging through the smartphone camera, this sensor-less technology allows controlling cardiac coherence biofeedback exercises through a simplified heart rate variability algorithm.

  6. Automatic segmentation of choroidal thickness in optical coherence tomography. (United States)

    Alonso-Caneiro, David; Read, Scott A; Collins, Michael J


    The assessment of choroidal thickness from optical coherence tomography (OCT) images of the human choroid is an important clinical and research task, since it provides valuable information regarding the eye's normal anatomy and physiology, and changes associated with various eye diseases and the development of refractive error. Due to the time consuming and subjective nature of manual image analysis, there is a need for the development of reliable objective automated methods of image segmentation to derive choroidal thickness measures. However, the detection of the two boundaries which delineate the choroid is a complicated and challenging task, in particular the detection of the outer choroidal boundary, due to a number of issues including: (i) the vascular ocular tissue is non-uniform and rich in non-homogeneous features, and (ii) the boundary can have a low contrast. In this paper, an automatic segmentation technique based on graph-search theory is presented to segment the inner choroidal boundary (ICB) and the outer choroidal boundary (OCB) to obtain the choroid thickness profile from OCT images. Before the segmentation, the B-scan is pre-processed to enhance the two boundaries of interest and to minimize the artifacts produced by surrounding features. The algorithm to detect the ICB is based on a simple edge filter and a directional weighted map penalty, while the algorithm to detect the OCB is based on OCT image enhancement and a dual brightness probability gradient. The method was tested on a large data set of images from a pediatric (1083 B-scans) and an adult (90 B-scans) population, which were previously manually segmented by an experienced observer. The results demonstrate the proposed method provides robust detection of the boundaries of interest and is a useful tool to extract clinical data.

  7. Electrophysiological and Anatomical Correlates of Spinal Cord Optical Coherence Tomography.

    Directory of Open Access Journals (Sweden)

    Mario E Giardini

    Full Text Available Despite the continuous improvement in medical imaging technology, visualizing the spinal cord poses severe problems due to structural or incidental causes, such as small access space and motion artifacts. In addition, positional guidance on the spinal cord is not commonly available during surgery, with the exception of neuronavigation techniques based on static pre-surgical data and of radiation-based methods, such as fluoroscopy. A fast, bedside, intraoperative real-time imaging, particularly necessary during the positioning of endoscopic probes or tools, is an unsolved issue. The objective of our work, performed on experimental rats, is to demonstrate potential intraoperative spinal cord imaging and probe guidance by optical coherence tomography (OCT. Concurrently, we aimed to demonstrate that the electromagnetic OCT irradiation exerted no particular effect at the neuronal and synaptic levels. OCT is a user-friendly, low-cost and endoscopy-compatible photonics-based imaging technique. In particular, by using a Fourier-domain OCT imager, operating at 850 nm wavelength and scanning transversally with respect to the spinal cord, we have been able to: 1 accurately image tissue structures in an animal model (muscle, spine bone, cerebro-spinal fluid, dura mater and spinal cord, and 2 identify the position of a recording microelectrode approaching and inserting into the cord tissue 3 check that the infrared radiation has no actual effect on the electrophysiological activity of spinal neurons. The technique, potentially extendable to full three-dimensional image reconstruction, shows prospective further application not only in endoscopic intraoperative analyses and for probe insertion guidance, but also in emergency and adverse situations (e.g. after trauma for damage recognition, diagnosis and fast image-guided intervention.

  8. PREFACE: XVIII International Youth Scientific School "Coherent Optics and Optical Spectroscopy" (United States)

    Salakhov, M. Kh; Samartsev, V. V.; Gainutdinov, R. Kh


    Kazan Federal University has held the annual International Youth School "Coherent Optics and Optical Spectroscopy" since 1997. The choice of the topic is not accidental. Kazan is the home of photon echo which was predicted at Kazan Physical-Technical Institute in 1963 by Prof. U.G. Kopvil'em and V.R. Nagibarov and observed in Columbia University by N.A. Kurnit, I.D. Abella, and S.R. Hartmann in 1964. Since then, photon echo has become a powerful tool of coherent optical spectroscopy and optical information processing, which have been developed here in Kazan in close collaboration between Kazan Physical-Technical Institute and Kazan Federal University. The main subjects of the XVIII International Youth School are: Nonlinear and coherent optics; Atomic and molecular spectroscopy; Coherent laser spectroscopy; Problems of quantum optics; Quantum theory of radiation; and Nanophotonics and Scanning Probe Microscopy. The unchallenged organizers of that school are Kazan Federal University and Kazan E.K. Zavoisky Physical-Technical Institute. The rector of the School is Professor Myakzyum Salakhov, and the vice-rector is Professor Vitaly Samartsev. The International Youth Scientific School "Coherent Optics and Optical Spectroscopy" follows the global pattern of comprehensive studies of matter properties and their interaction with electromagnetic fields. Since 1997 more than 100 famous scientists from the USA, Germany, Ukraine, Belarus and Russia have given plenary lecture presentations. Here over 1000 young scientists had an opportunity to participate in lively discussions about the latest scientific news. Many young people have submitted interesting reports on photonics, quantum electronics, laser physics, quantum optics, traditional optical and laser spectroscopy, non-linear optics, material science and nanotechnology. Here we are publishing the fullsize papers prepared from the most interesting lectures and reports selected by the Program Committee of the School. The

  9. Advanced Equalization Techniques for Digital Coherent Optical Receivers

    DEFF Research Database (Denmark)

    Arlunno, Valeria

    This PhD thesis addresses the design and performance evaluation of advanced Digital Signal Processing (DSP) algorithms for coherent optical fiber transmission systems. The research results presented in this thesis report on transmission of highly spectrally efficient optical communication systems...... employing multiplexing techniques with polarization multiplexing and multi-level modulations format. Advanced digital signal processing techniques offer robustness and flexibility for next generation high capacity optical fibre networks and are therefore considered as key building blocks in next generation...... format detection. Feedback equalization structure have been investigated in high order modulation formats transmission, when combined with coding techniques, and for closed spaced multiplexing scenario. Highlight results presented in this PhD thesis include evaluation and implementation of a novel...

  10. Repeatability and reproducibility of optic nerve head perfusion measurements using optical coherence tomography angiography (United States)

    Chen, Chieh-Li; Bojikian, Karine D.; Xin, Chen; Wen, Joanne C.; Gupta, Divakar; Zhang, Qinqin; Mudumbai, Raghu C.; Johnstone, Murray A.; Chen, Philip P.; Wang, Ruikang K.


    Optical coherence tomography angiography (OCTA) has increasingly become a clinically useful technique in ophthalmic imaging. We evaluate the repeatability and reproducibility of blood perfusion in the optic nerve head (ONH) measured using optical microangiography (OMAG)-based OCTA. Ten eyes from 10 healthy volunteers are recruited and scanned three times with a 68-kHz Cirrus HD-OCT 5000-based OMAG prototype system (Carl Zeiss Meditec Inc., Dublin, California) centered at the ONH involving two separate visits within six weeks. Vascular images are generated with OMAG processing by detecting the differences in OCT signals between consecutive B-scans acquired at the same retina location. ONH perfusion is quantified as flux, vessel area density, and normalized flux within the ONH for the prelaminar, lamina cribrosa, and the full ONH. Coefficient of variation (CV) and intraclass correlation coefficient (ICC) are used to evaluate intravisit and intervisit repeatability, and interobserver reproducibility. ONH perfusion measurements show high repeatability [CV≤3.7% (intravisit) and ≤5.2% (intervisit)] and interobserver reproducibility (ICC≤0.966) in all three layers by three metrics. OCTA provides a noninvasive method to visualize and quantify ONH perfusion in human eyes with excellent repeatability and reproducibility, which may add additional insight into ONH perfusion in clinical practice.

  11. Optical imaging of oral pathological tissue using optical coherence tomography and synchrotron radiation computed microtomography (United States)

    Cânjǎu, Silvana; Todea, Carmen; Sinescu, Cosmin; Negrutiu, Meda L.; Duma, Virgil; Mǎnescu, Adrian; Topalǎ, Florin I.; Podoleanu, Adrian Gh.


    The efforts aimed at early diagnosis of oral cancer should be prioritized towards developing a new screening instrument, based on optical coherence tomography (OCT), to be used directly intraorally, able to perform a fast, real time, 3D and non-invasive diagnosis of oral malignancies. The first step in this direction would be to optimize the OCT image interpretation of oral tissues. Therefore we propose plastination as a tissue preparation method that better preserves three-dimensional structure for study by new optical imaging techniques. The OCT and the synchrotron radiation computed microtomography (micro-CT) were employed for tissue sample analyze. For validating the OCT results we used the gold standard diagnostic procedure for any suspicious lesion - histopathology. This is a preliminary study of comparing features provided by OCT and Micro-CT. In the conditions of the present study, OCT proves to be a highly promising imaging modality. The use of x-ray based topographic imaging of small biological samples has been limited by the low intrinsic x-ray absorption of non-mineralized tissue and the lack of established contrast agents. Plastination can be used to enhance optical imagies of oral soft tissue samples.

  12. An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography. (United States)

    Eom, Jonghyun; Shin, Jun Geun; Park, Soongho; Rim, Sunghwan; Lee, Byeong Ha


    We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT) and optical coherence tomography (OCT). The PAT remotely measures photoacoustic (PA) signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF) and a large-core multimode fiber (MMF). The compact and robust common probe is capable of obtaining both the PA and the OCT signals at the same position without any physical contact. Additionally, the MMF of the probe delivers the short pulses of a Nd:YAG laser to efficiently excite the PA signals. We experimentally demonstrate the feasibility of the proposed dual-modal system with a phantom made of a fishing line and a black polyethylene terephthalate fiber in a tissue mimicking solution. The all-fiber-optic system, capable of providing complementary information about absorption and scattering, has a promising potential in minimally invasive and endoscopic imaging.

  13. Few-photon coherent nonlinear optics with a single molecule

    CERN Document Server

    Maser, Andreas; Utikal, Tobias; Götzinger, Stephan; Sandoghdar, Vahid


    The pioneering experiments of linear spectroscopy were performed using flames in the 1800s, but nonlinear optical measurements had to wait until lasers became available in the twentieth century. Because the nonlinear cross section of materials is very small, usually macroscopic bulk samples and pulsed lasers are used. Numerous efforts have explored coherent nonlinear signal generation from individual nanoparticles or small atomic ensembles with millions of atoms. Experiments on a single semiconductor quantum dot have also been reported, albeit with a very small yield. Here, we report on coherent nonlinear spectroscopy of a single molecule under continuous-wave single-pass illumination, where efficient photon-molecule coupling in a tight focus allows switching of a laser beam by less than a handful of pump photons nearly resonant with the sharp molecular transition. Aside from their fundamental importance, our results emphasize the potential of organic molecules for applications such as quantum information pro...

  14. Quantum repeater based on cavity QED evolutions and coherent light (United States)

    Gonţa, Denis; van Loock, Peter


    In the framework of cavity QED, we propose a quantum repeater scheme that uses coherent light and chains of atoms coupled to optical cavities. In contrast to conventional repeater schemes, in our scheme there is no need for an explicit use of two-qubit quantum logical gates by exploiting solely the cavity QED evolution. In our previous work (Gonta and van Loock in Phys Rev A 88:052308, 2013), we already proposed a quantum repeater in which the entanglement between two neighboring repeater nodes was distributed using controlled displacements of input coherent light, while the produced low-fidelity entangled pairs were purified using ancillary (four-partite) entangled states. In the present work, the entanglement distribution is realized using a sequence of controlled phase shifts and displacements of input coherent light. Compared to previous coherent-state-based distribution schemes for two-qubit entanglement, our scheme here relies only upon a simple discrimination of two coherent states with opposite signs, which can be performed in a quantum mechanically optimal fashion via a beam splitter and two on-off detectors. For the entanglement purification, we employ a method that avoids the use of extra entangled ancilla states. Our repeater scheme exhibits reasonable fidelities and repeater rates providing an attractive platform for long-distance quantum communication.

  15. Invited Article: The coherent optical laser beam recombination technique (COLBERT) spectrometer: Coherent multidimensional spectroscopy made easier (United States)

    Turner, Daniel B.; Stone, Katherine W.; Gundogdu, Kenan; Nelson, Keith A.


    We have developed an efficient spectrometer capable of performing a wide variety of coherent multidimensional measurements at optical wavelengths. The two major components of the largely automated device are a spatial beam shaper which controls the beam geometry and a spatiotemporal pulse shaper which controls the temporal waveform of the femtosecond pulse in each beam. We describe how to construct, calibrate, and operate the device, and we discuss its limitations. We use the exciton states of a semiconductor nanostructure as a working example. A series of complex multidimensional spectra—displayed in amplitude and real parts—reveals increasingly intricate correlations among the excitons.

  16. Fast dispersion estimation in coherent optical 16QAM fast OFDM systems. (United States)

    Zhao, J; Shams, H


    Fast channel estimation is crucial to increase the payload efficiency which is of particular importance for optical packet networks. In this paper, we propose a novel least-square based dispersion estimation method in coherent optical fast OFDM (F-OFDM) systems. Additionally, we experimentally demonstrate for the first time a 37.5 Gb/s 16QAM coherent F-OFDM system with 480 km transmission using the proposed scheme. The results show that this method outperforms the conventional channel estimation methods in minimizing the overhead load. A single training symbol can achieve near-optimum channel estimation without any prior information of the transmission distance. This makes optical F-OFDM a very promising scheme for the future burst-mode applications.

  17. Dual focused coherent beams for three-dimensional optical trapping and continuous rotation of metallic nanostructures (United States)

    Xu, Xiaohao; Cheng, Chang; Zhang, Yao; Lei, Hongxiang; Li, Baojun


    Metallic nanoparticles and nanowires are extremely important for nanoscience and nanotechnology. Techniques to optically trap and rotate metallic nanostructures can enable their potential applications. However, because of the destabilizing effects of optical radiation pressure, the optical trapping of large metallic particles in three dimensions is challenging. Additionally, the photothermal issues associated with optical rotation of metallic nanowires have far prevented their practical applications. Here, we utilize dual focused coherent beams to realize three-dimensional (3D) optical trapping of large silver particles. Continuous rotation of silver nanowires with frequencies measured in several hertz is also demonstrated based on interference-induced optical vortices with very low local light intensity. The experiments are interpreted by numerical simulations and calculations.

  18. Miniature endoscopic optical coherence tomography for calculus detection. (United States)

    Kao, Meng-Chun; Lin, Chun-Li; Kung, Che-Yen; Huang, Yi-Fung; Kuo, Wen-Chuan


    The effective treatment of periodontitis involves the detection and removal of subgingival dental calculus. However, subgingival calculus is more difficult to detect than supragingival calculus because it is firmly attached to root surfaces within periodontal pockets. To achieve a smooth root surface, clinicians often remove excessive amounts of root structure because of decreased visibility. In addition, enamel pearl, a rare type of ectopic enamel formation on the root surface, can easily be confused with dental calculus in the subgingival environment. In this study, we developed a fiber-probe swept-source optical coherence tomography (SSOCT) technique and combined it with the quantitative measurement of an optical parameter [standard deviation (SD) of the optical coherence tomography (OCT) intensity] to differentiate subgingival calculus from sound enamel, including enamel pearl. Two-dimensional circumferential images were constructed by rotating the miniprobe (0.9 mm diameter) while acquiring image lines, and the adjacent lines in each rotation were stacked to generate a three-dimensional volume. In OCT images, compared to sound enamel and enamel pearls, dental calculus showed significant differences (Pcalculus.

  19. Coherent transport of matter waves in disordered optical potentials

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, Robert


    The development of modern techniques for the cooling and the manipulation of atoms in recent years, and the possibility to create Bose-Einstein condensates and degenerate Fermi gases and to load them into regular optical lattices or disordered optical potentials, has evoked new interest for the disorder-induced localization of ultra-cold atoms. This work studies the transport properties of matter waves in disordered optical potentials, which are also known as speckle potentials. The effect of correlated disorder on localization is first studied numerically in the framework of the Anderson model. The relevant transport parameters in the configuration average over many different realizations of the speckle potential are then determined analytically, using self-consistent diagrammatic perturbation techniques. This allows to make predictions for a possible experimental observation of coherent transport phenomena for cold atoms in speckle potentials. Of particular importance are the spatial correlations of the speckle fluctuations, which are responsible for the anisotropic character of the single scattering processes in the effective medium. Coherent multiple scattering leads to quantum interference effects, which entail a renormalization of the diffusion constant as compared to the classical description. This so-called weak localization of matter waves is studied as the underlying mechanism for the disorder-driven transition to the Anderson-localization regime, explicitly taking into account the correlations of the speckle fluctuations. (orig.)

  20. Functional Doppler optical coherence tomography for cortical blood flow imaging (United States)

    Yu, Lingfeng; Liu, Gangjun; Nguyen, Elaine; Choi, Bernard; Chen, Zhongping


    Optical methods have been widely used in basic neuroscience research to study the cerebral blood flow dynamics in order to overcome the low spatial resolution associated with magnetic resonance imaging and positron emission tomography. Although laser Doppler imaging and laser speckle imaging can map out en face cortical hemodynamics and columns, depth resolution is not available. Two-photon microscopy has been used for mapping cortical activity. However, flow measurement requires fluorescent dye injection, which can be problematic. The noninvasive and high resolution tomographic capabilities of optical coherence tomography make it a promising technique for mapping depth resolved cortical blood flow. Here, we present a functional Doppler optical coherence tomography (OCT) imaging modality for quantitative evaluation of cortical blood flow in a mouse model. Fast, repeated, Doppler OCT scans across a vessel of interest were performed to record flow dynamic information with a high temporal resolution of the cardiac cycles. Spectral Doppler analysis of continuous Doppler images demonstrates how the velocity components and longitudinally projected flow-volume-rate change over time, thereby providing complementary temporal flow information to the spatially distributed flow information of Doppler OCT. The proposed functional Doppler OCT imaging modality can be used to diagnose vessel stenosis/blockage or monitor blood flow changes due to pharmacological agents/neuronal activities. Non-invasive in-vivo mice experiments were performed to verify the capabilities of function Doppler OCT.

  1. Fiber optic low-coherence Michelson interferometer for silicon growth measurement (United States)

    Michael, Robert R., Jr.; Lawson, Christopher M.


    We report on the use of optical low coherence reflectometry for silicon characterization. The measurement system uses a low coherence light source (edge-emitting LED) in conjunction with a fiber optic Michelson interferometer. This non-contact fiber optic measurement system has been used to measure silicon thickness and flatness to an accuracy of +/- 1.5 micrometers in the laboratory.

  2. Differentiating Mild Papilledema and Buried Optic Nerve Head Drusen Using Spectral Domain Optical Coherence Tomography (United States)

    Kulkarni, Kaushal M.; Pasol, Joshua; Rosa, Potyra R.; Lam, Byron L.


    Purpose To evaluate the clinical utility of spectral domain optical coherence tomography (SD-OCT) in differentiating mild papilledema from buried optic nerve head drusen (ONHD). Design Comparative case series. Participants 16 eyes of 9 patients with ultrasound-proven buried ONHD, 12 eyes of 6 patients with less than or equal to Frisén grade 2 papilledema due to idiopathic intracranial hypertension. 2 normal fellow eyes of patients with buried ONHD were included. Methods A raster scan on the optic nerve and retinal nerve fiber layer (RNFL) thickness analysis was performed on each eye using SD-OCT. Eight eyes underwent enhanced depth imaging SD-OCT. Images were assessed qualitatively and quantitatively to identify differentiating features between buried ONHD and papilledema. Five clinicians trained with a tutorial and masked to the underlying diagnosis reviewed the SD-OCT images of each eye independently to determine the diagnosis. Main outcome measures Differences in RNFL thickness in each quadrant between the two groups, and diagnostic accuracy of five independent clinicians based on the SD-OCT images alone. Results We found no statistically significant difference in RNFL thickness between buried ONHD and papilledema in any of the four quadrants. Diagnostic accuracy among the readers was low and ranged from 50–64%. The kappa coefficient of agreement among the readers was 0.35 (95% Confidence interval: 0.19, 0.54). Conclusions SD-OCT is not clinically reliable in differentiating buried ONHD and mild papilledema. PMID:24321144

  3. Optical coherence tomography imaging of ocular and periocular tumours (United States)

    Medina, Carlos A; Plesec, Thomas; Singh, Arun D


    Optical coherence tomography (OCT) has become pivotal in the practice of ophthalmology. Similar to other ophthalmic subspecialties, ophthalmic oncology has also incorporated OCT into practice. Anterior segment OCT (AS-OCT), ultra-high resolution OCT (UHR-OCT), spectral domain OCT (SD-OCT) and enhanced depth imaging OCT (EDI-OCT), have all been described to be helpful in the diagnosis, treatment planning and monitoring response of ocular and periocular tumours. Herein we discuss the role of OCT including the advantages and limitations of its use in the setting of common intraocular and adnexal tumours. PMID:24599420

  4. Primate retina imaging with polarization-sensitive optical coherence tomography (United States)

    Ducros, Mathieu G.; Marsack, Jason D.; Rylander, H. Grady; Thomsen, Sharon L.; Milner, Thomas E.


    Polarization-sensitive optical coherence tomography (PSOCT) is applied to determine the depth-resolved polarization state of light backreflected from the eye. The birefringence of the retinal nerve fiber layer (RNFL) was observed and measured from PSOCT images recorded postmortem in a Rhesus monkey. An image-processing algorithm was developed to identify birefringent regions in acquired PSOCT retinal images and automatically determine the thickness of the RNFL. Values of the RNFL thickness determined from histology and PSOCT were compared. PSOCT may provide a new method to determine RNFL thickness and birefringence for glaucoma diagnostics.

  5. Probing beyond the laser coherence time in optical clock comparisons (United States)

    Hume, David B.; Leibrandt, David R.


    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.

  6. Single fiber perfusion phantom for optical coherence tomography (United States)

    Podlipná, Petra; Kolář, Radim


    This paper presents the successful creation of new phantom for optical coherence tomography (OCT) aimed on perfusion simulation. The phantom is created from syringe pump and polypropylene hollow fiber with porous walls embeded in the glass capillary to provide small outer environment. Its function was tested by gold nanorods as a flowing medium and imaged by commercial swept-source OCT system. Results showed that the fiber is permeable for used gold nanorods which are frequently declared as possible contrast agents for OCT and this permeability can be displayed by OCT.

  7. Detection of dermal systemic sclerosis using noncontact optical coherence elastography (United States)

    Liu, Chih-Hao; Du, Yong; Singh, Manmohan; Li, Jiasong; Wu, Chen; Han, Zhaolong; Raghunathan, Raksha; Hsu, Thomas; Noorani, Shezaan; Hicks, M. John; Mohan, Chandra; Larin, Kirill V.


    Systemic sclerosis (SSc) is a connective tissue disease that results in excessive accumulation of collagen in the skin and internal organs. Overall, SSc is a rare disorder, but has a high mortality, particularly in last decade of life. To improve the survival rate, an accurate and early diagnosis is crucial. Currently, the modified Rodnan skin score (mRSS) is the gold standard for evaluating SSc progression based on clinical palpation at 17 sites on the body. However, this procedure can be time consuming, and the assessed score may be biased by the experience of the clinician, causing inter- and intraobserver variabilities. Moreover, the instrinsic elasticity of skin may further bias the mRSS assessment in the early stages of SSc, such as oedematous. To overcome these limitations, there is a need for a rapid, accurate, and objective assessment technique. Optical coherence elastography (OCE) is a novel, rapidly emerging technique, which can assess mechanical contrast in tissues with micrometer spatial resolution. In this work, we demonstrate the first use of OCE to assess the mechanical properties of control and SSc-like diseased skin non-invasively. A focused air-pulse induced an elastic wave in the skin, which was detected by a home-built OCE system. The elastic wave propagated significantly faster in SSc skin compared to healthy skin. The Young's modulus of the SSc skin was significantly higher than that of normal skin (P<0.05). Thus, OCE was able to objectively differentiate healthy and fibrotic skin completely noninvasively and is a promising and potentially useful new technology for quantifying skin involvement in SSc.

  8. Optical coherence tomography for blood glucose monitoring through signal attenuation (United States)

    De Pretto, Lucas R.; Yoshimura, Tania M.; Ribeiro, Martha S.; de Freitas, Anderson Z.


    Development of non-invasive techniques for glucose monitoring is crucial to improve glucose control and treatment adherence in patients with diabetes. Hereafter, Optical Coherence Tomography (OCT) may offer a good alternative for portable glucometers, since it uses light to probe samples. Changes in the object of interest can alter the intensity of light returning from the sample and, through it, one can estimate the sample's attenuation coefficient (μt) of light. In this work, we aimed to explore the behavior of μt of mouse's blood under increasing glucose concentrations. Different samples were prepared in four glucose concentrations using a mixture of heparinized blood, phosphate buffer saline and glucose. Blood glucose concentrations were measured with a blood glucometer, for reference. We have also prepared other samples diluting the blood in isotonic saline solution to check the effect of a higher multiple-scattering component on the ability of the technique to differentiate glucose levels based on μt. The OCT system used was a commercial Spectral Radar OCT with 930 nm central wavelength and spectral bandwidth (FWHM) of 100 nm. The system proved to be sensitive for all blood glucose concentrations tested, with good correlations with the obtained attenuation coefficients. A linear tendency was observed, with an increase in attenuation with higher values of glucose. Statistical difference was observed between all groups (p<0.001). This work opens the possibility towards a non-invasive diagnostic modality using OCT for glycemic control, which eliminates the use of analytes and/or test strips, as in the case with commercially available glucometers.

  9. Polarization-sensitive swept-source optical coherence tomography with continuous source polarization modulation


    Yamanari, Masahiro; Makita, Shuichi; Yasuno, Yoshiaki


    We present fiber-based polarization-sensitive swept-source optical coherence tomography (SS-OCT) based on continuous source polarization modulation. The light source is a frequency swept laser centered at 1.31 μm with a scanning rate of 20 kHz. The incident polarization is modulated by a resonant electro-optic modulator at 33.3 MHz, which is one-third of the data acquisition frequency. The zeroth- and first-order harmonic components of the OCT signals with respect to the polarization modulati...

  10. Quantitative characterization of developing collagen gels using optical coherence tomography (United States)

    Levitz, David; Hinds, Monica T.; Choudhury, Niloy; Tran, Noi T.; Hanson, Stephen R.; Jacques, Steven L.


    Nondestructive optical imaging methods such as optical coherence tomography (OCT) have been proposed for characterizing engineered tissues such as collagen gels. In our study, OCT was used to image collagen gels with different seeding densities of smooth muscle cells (SMCs), including acellular gels, over a five-day period during which the gels contracted and became turbid with increased optical scattering. The gels were characterized quantitatively by their optical properties, specified by analysis of OCT data using a theoretical model. At 6 h, seeded cell density and scattering coefficient (μs) were correlated, with μs equal to 10.8 cm-1/(106 cells/mL). Seeded cell density and the scattering anisotropy (g) were uncorrelated. Over five days, the reflectivity in SMC gels gradually doubled with little change in optical attenuation, which indicated a decrease in g that increased backscatter, but only a small drop in μs. At five days, a subpopulation of sites on the gel showed substantially higher reflectivity (approximately a tenfold increase from the first 24 h). In summary, the increased turbidity of SMC gels that develops over time is due to a change in the structure of collagen, which affects g, and not simply due to a change in number density of collagen fibers due to contraction.

  11. Monte Carlo Simulations of Arterial Imaging with Optical Coherence Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Amendt, P.; Estabrook, K.; Everett, M.; London, R.A.; Maitland, D.; Zimmerman, G.; Colston, B.; da Silva, L.; Sathyam, U.


    The laser-tissue interaction code LATIS [London et al., Appl. Optics 36, 9068 ( 1998)] is used to analyze photon scattering histories representative of optical coherence tomography (OCT) experiment performed at Lawrence Livermore National Laboratory. Monte Carlo photonics with Henyey-Greenstein anisotropic scattering is implemented and used to simulate signal discrimination of intravascular structure. An analytic model is developed and used to obtain a scaling law relation for optimization of the OCT signal and to validate Monte Carlo photonics. The appropriateness of the Henyey-Greenstein phase function is studied by direct comparison with more detailed Mie scattering theory using an ensemble of spherical dielectric scatterers. Modest differences are found between the two prescriptions for describing photon angular scattering in tissue. In particular, the Mie scattering phase functions provide less overall reflectance signal but more signal contrast compared to the Henyey-Greenstein formulation.

  12. 8th Rochester Conference on Coherence and Quantum Optics

    CERN Document Server


    The Eighth Rochester Conference on Coherence and Quantum Optics was held on the campus of the University of Rochester during the period June 13-16,2001. This volume contains the proceedings of the meeting. The meeting was preceded by an affiliated conference, the International Conference on Quantum Information, with some overlapping sessions on June 13. The proceedings of the affiliated conference will be published separately by the Optical Society of America. A few papers that were presented in common plenary sessions of the two conferences will be published in both proceedings volumes. More than 268 scientists from 28 countries participated in the week long discussions and presentations. This Conference differed from the previous seven in the CQO series in several ways, the most important of which was the absence of Leonard Mandel. Professor Mandel died a few months before the conference. A special memorial symposium in his honor was held at the end of the conference. The presentations from that sym...

  13. Imaging of oral pathological tissue using optical coherence tomography (United States)

    Canjau, Silvana; Todea, Carmen; Sinescu, Cosmin; Duma, Virgil-Florin; Topala, Florin I.; Podoleanu, Adrian G.


    Oral squamous cell carcinoma (OSCC) constitutes 90% of oral cancer. Early detection is a cornerstone to improve survival. Interaction of light with tissues may highlight changes in tissue structure and metabolism. We propose optical coherence tomography (OCT), as a non-invasive diagnosis method, being a new high-resolution optical technique that permits tri-dimensional (3-D), real-time imaging of near surface abnormalities in complex tissues. In this study half of the excisional biopsy was directed to the pathologist and the other half was assigned for OCT investigation. Histopathology validated the results. Areas of OSCC of the buccal mucosa were identified in the OCT images. The elements obserced included extensive epithelial down-growth, the disruption of the basement membrane, with areas of erosion, an epithelial layer that was highly variable in thickness and invasion into the sub-epithelial layers. Therefore, OCT appears to be a highly promising imaging modality.

  14. Gauss-Bonnet gravity, relic coherent gravitons and optical chaos

    CERN Document Server

    Crowell, Lawrence B


    We discuss the production of massive relic coherent gravitons in Gauss-Bonnet gravity and their possible imprint in Cosmic Microwave Background. In fact, in the very early universe these relic gravitons could have acted as slow gravity waves. They may have then acted to focus the geodesics of radiation and matter. Therefore, their imprint on the later evolution of the universe could appear as filaments and domain wall in the Universe today. In that case, the effect on Cosmic Microwave Background should be analogous to the effect of water waves, which, in focusing light, create optical caustics which are commonly seen on the bottom of swimming pools. We analyze this important issue by showing how relic massive GWs perturb the trajectories of Cosmic Microwave Background photons (gravitational lensing by relic GWs). The consequence of the type of physics discussed is outlined by illustrating an amplification of what might be called optical chaos.

  15. Polarization Drift Channel Model for Coherent Fibre-Optic Systems

    CERN Document Server

    Czegledi, Cristian B; Agrell, Erik; Johannisson, Pontus


    A theoretical framework is introduced to model the dynamical changes of the state of polarization during transmission in coherent fibre-optic systems. The model generalizes the one-dimensional phase noise random walk to higher dimensions, accounting for random polarization drifts. The model is described in the Jones, Stokes and real 4-dimensional formalisms, and the mapping between them is derived. Such a model will be increasingly important in simulating and optimizing future optical systems, which to a higher and higher degree rely on transmission and detection on both polarizations jointly using sophisticated digital signal processing. Such analysis cannot be carried out using the more rudimentary polarization drift models in use today, which only account for deterministic effects. The proposed polarization drift model is the first of its kind and will likely be useful in a wide-range of photonics applications where stochastic polarization fluctuation is an issue.

  16. Performance analysis of multihop coherent OFDM free-space optical communication systems (United States)

    Wang, Yi; Wang, Deli; Ma, Jing


    This paper proposes a multihop coherent orthogonal frequency division multiplexing free space optical (OFDM-FSO) communication system model based on a relay transmission mode of decode and forward (DF) with the Gamma-Gamma channel. In the study of atmospheric statistical model, mainly considering the combined action by the following three aspects, they are the light intensity scintillation caused by the atmospheric turbulence, the pointing error caused the transmitter and the receiver without aiming at each other and the path loss. We derived closed-form expressions of outage probability and symbol error rate of the multihop coherent OFDM-FSO system with serial DF relay transmission. We simulated and analyzed the influence of the atmospheric turbulence, the modulation order, the beam width and the jitter factor on the communication interruption performance and bit error performance of the multihop coherent OFDM-FSO system with different number of hops.

  17. Coherent optical array receiver for PPM signals under atmospheric turbulence (United States)

    Munoz Fernandez, Michela

    The performance of a coherent free-space optical communications system operating in the presence of turbulence is investigated. Maximum Likelihood Detection techniques are employed to optimally detect Pulse Position Modulated signals with a focal-plane detector array and to reconstruct the turbulence-degraded signals. Laboratory equipment and experimental setup used to carry out these experiments at the Jet Propulsion Laboratory are described. The key components include two lasers operating at 1064 nm wavelength for use with coherent detection, a 16 element (4 X 4) InGaAs focal-plane detector array, and a data-acquisition and signal-processing assembly needed to sample and collect the data and analyze the results. The detected signals are combined using the least-mean-square (LMS) algorithm. In the first part of the experimental results we show convergence of the algorithm for experimentally obtained signal tones in the presence of atmospheric turbulence. The second part of the experimental results shows adaptive combining of experimentally obtained heterodyned pulse position modulated (PPM) signals with pulse-to-pulse coherence in the presence of simulated spatial distortions resembling atmospheric turbulence. The adaptively combined PPM signals are phased up via an LMS algorithm suitably optimized to operate with PPM in the presence of additive shot noise. A convergence analysis of the algorithm is presented, and results with both computer-simulated and experimentally obtained PPM signals are analyzed. The third part of the experimental results, in which the main goal of this thesis is achieved, includes an investigation of the performance of the Coherent Optical Receiver Experiment (CORE) at JPL. Bit Error Rate (BER) results are presented for single and multichannel optical receivers where quasi shot noise-limited performance is achieved under simulated turbulence conditions using noncoherent postdetection processing techniques. Theoretical BER expressions are

  18. Subluxed traumatic cataract: optical coherence tomography findings and clinical management

    Directory of Open Access Journals (Sweden)

    Kuriyan AE


    Full Text Available Ajay E Kuriyan, Harry W Flynn Jr, Sonia H YooDepartment of Ophthalmology, Bascom Palmer Eye Institute, University of Miami, Miami, FLAbstract: This case report describes the optical coherence tomography (OCT findings and clinical management of a patient with traumatic subluxed cataract. The patient presented with a traumatic subluxed cataract and vitreous prolapse into the anterior chamber. The anterior segment OCT showed vacuoles in the anterior subcapsular regions of the crystalline lens. The patient was treated with pars plana lensectomy, vitrectomy, and placement of an anterior chamber intraocular lens. The patient's best corrected visual acuity improved from hand motion at presentation to 20/25 during 3 years of follow-up. Anterior segment OCT demonstrates that the clinically visible vacuoles in traumatic cataract are located in the anterior subcapsular part of the lens. This is the first report in the literature using anterior segment OCT to visualize the subcapsular vacuolar changes in a traumatic cataract.Keywords: traumatic cataract, subluxed lens, vacuoles, anterior chamber intraocular lens, anterior segment optical coherence tomography

  19. High-speed optical coherence tomography signal processing on GPU

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiqi; Shi Guohua; Zhang Yudong, E-mail: [Laboratory on Adaptive Optics, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209 (China)


    The signal processing speed of spectral domain optical coherence tomography (SD-OCT) has become a bottleneck in many medical applications. Recently, a time-domain interpolation method was proposed. This method not only gets a better signal-to noise ratio (SNR) but also gets a faster signal processing time for the SD-OCT than the widely used zero-padding interpolation method. Furthermore, the re-sampled data is obtained by convoluting the acquired data and the coefficients in time domain. Thus, a lot of interpolations can be performed concurrently. So, this interpolation method is suitable for parallel computing. An ultra-high optical coherence tomography signal processing can be realized by using graphics processing unit (GPU) with computer unified device architecture (CUDA). This paper will introduce the signal processing steps of SD-OCT on GPU. An experiment is performed to acquire a frame SD-OCT data (400A-linesx2048 pixel per A-line) and real-time processed the data on GPU. The results show that it can be finished in 6.208 milliseconds, which is 37 times faster than that on Central Processing Unit (CPU).

  20. Automatic airway wall segmentation and thickness measurement for long-range optical coherence tomography images. (United States)

    Qi, Li; Huang, Shenghai; Heidari, Andrew E; Dai, Cuixia; Zhu, Jiang; Zhang, Xuping; Chen, Zhongping


    We present an automatic segmentation method for the delineation and quantitative thickness measurement of multiple layers in endoscopic airway optical coherence tomography (OCT) images. The boundaries of the mucosa and the sub-mucosa layers are accurately extracted using a graph-theory-based dynamic programming algorithm. The algorithm was tested with sheep airway OCT images. Quantitative thicknesses of the mucosal layers are obtained automatically for smoke inhalation injury experiments.

  1. Experimental demonstration of the maximum likelihood-based chromatic dispersion estimator for coherent receivers

    DEFF Research Database (Denmark)

    Borkowski, Robert; Johannisson, Pontus; Wymeersch, Henk;


    We perform an experimental investigation of a maximum likelihood-based (ML-based) algorithm for bulk chromatic dispersion estimation for digital coherent receivers operating in uncompensated optical networks. We demonstrate the robustness of the method at low optical signal-to-noise ratio (OSNR) ...

  2. Operation of an optically coherent frequency comb outside the metrology lab

    CERN Document Server

    Sinclair, Laura C; Swann, William C; Rieker, Greg B; Hati, Archita; Iwakuni, Kana; Newbury, Nathan R


    We demonstrate a self-referenced fiber frequency comb that can operate outside the well-controlled optical laboratory. The frequency comb has residual optical linewidths of < 1 Hz, sub-radian residual optical phase noise, and residual pulse-to-pulse timing jitter of 2.4 - 5 fs, when locked to an optical reference. This fully phase-locked frequency comb has been successfully operated in a moving vehicle with 0.5 g peak accelerations and on a shaker table with a sustained 0.5 g rms integrated acceleration, while retaining its optical coherence and 5-fs-level timing jitter. This frequency comb should enable metrological measurements outside the laboratory with the precision and accuracy that are the hallmarks of comb-based systems. Work of the U.S. government, not subject to copyright

  3. Operation of an optically coherent frequency comb outside the metrology lab. (United States)

    Sinclair, L C; Coddington, I; Swann, W C; Rieker, G B; Hati, A; Iwakuni, K; Newbury, N R


    We demonstrate a self-referenced fiber frequency comb that can operate outside the well-controlled optical laboratory. The frequency comb has residual optical linewidths of < 1 Hz, sub-radian residual optical phase noise, and residual pulse-to-pulse timing jitter of 2.4 - 5 fs, when locked to an optical reference. This fully phase-locked frequency comb has been successfully operated in a moving vehicle with 0.5 g peak accelerations and on a shaker table with a sustained 0.5 g rms integrated acceleration, while retaining its optical coherence and 5-fs-level timing jitter. This frequency comb should enable metrological measurements outside the laboratory with the precision and accuracy that are the hallmarks of comb-based systems.

  4. Development and Application of Multifunctional Optical Coherence Tomography (United States)

    Zhi, Zhongwei

    Microcirculation refers to the functions of capillaries and the neighboring lymphatic vessels. It plays a vital role in the pathophysiology of disorders in many clinical areas including cardiology, dermatology, neurology and ophthalmology, and so forth. It is crucial to develop imaging technologies that can provide both qualitative and quantitative information as to how microcirculation responds to certain injury and/or disease, and its treatment. Optical coherence tomography (OCT) is a non-invasive optical imaging technique for high-resolution cross-sectional imaging of specimens, with many applications in clinical medicine. Current state-of-the-art OCT systems operate in the Fourier domain, using either a broadband light source with a spectrometer, known as spectral domain OCT (SDOCT), or a rapidly tunable laser, known as swept source OCT (SSOCT). The current Fourier domain OCT systems have dramatically improvement in sensitivity, resolution and speed compared to time domain OCT. In addition to the improvement in the OCT system hardware, different methods for functional measurements of tissue beds have been developed and demonstrated. This includes but not limited to, i) Phase-resolved Doppler OCT for quantifying the blood flow, ii) OCT angiography for visualization of microvasculature, iii) Polarization sensitive OCT for measuring the intrinsic optical property/ birefringence of tissue, iv) spectroscopic OCT for measuring blood oxygenation, etc. Functional OCT can provide important clinical information that is not available in the typical intensity based structural OCT images. Among these functional OCT modalities, Doppler OCT and OCT angiography attract great interests as they show high capability for in vivo study of microvascular pathology. By analyzing the Doppler effect of a flowing particle on light frequency, Doppler OCT allows the quantification of the blood flow speed and blood flow rate. The most popular approach for Doppler OCT is achieved through

  5. 3D Human cartilage surface characterization by optical coherence tomography (United States)

    Brill, Nicolai; Riedel, Jörn; Schmitt, Robert; Tingart, Markus; Truhn, Daniel; Pufe, Thomas; Jahr, Holger; Nebelung, Sven


    Early diagnosis and treatment of cartilage degeneration is of high clinical interest. Loss of surface integrity is considered one of the earliest and most reliable signs of degeneration, but cannot currently be evaluated objectively. Optical Coherence Tomography (OCT) is an arthroscopically available light-based non-destructive real-time imaging technology that allows imaging at micrometre resolutions to millimetre depths. As OCT-based surface evaluation standards remain to be defined, the present study investigated the diagnostic potential of 3D surface profile parameters in the comprehensive evaluation of cartilage degeneration. To this end, 45 cartilage samples of different degenerative grades were obtained from total knee replacements (2 males, 10 females; mean age 63.8 years), cut to standard size and imaged using a spectral-domain OCT device (Thorlabs, Germany). 3D OCT datasets of 8  ×  8, 4  ×  4 and 1  ×  1 mm (width  ×  length) were obtained and pre-processed (image adjustments, morphological filtering). Subsequent automated surface identification algorithms were used to obtain the 3D primary profiles, which were then filtered and processed using established algorithms employing ISO standards. The 3D surface profile thus obtained was used to calculate a set of 21 3D surface profile parameters, i.e. height (e.g. Sa), functional (e.g. Sk), hybrid (e.g. Sdq) and segmentation-related parameters (e.g. Spd). Samples underwent reference histological assessment according to the Degenerative Joint Disease classification. Statistical analyses included calculation of Spearman’s rho and assessment of inter-group differences using the Kruskal Wallis test. Overall, the majority of 3D surface profile parameters revealed significant degeneration-dependent differences and correlations with the exception of severe end-stage degeneration and were of distinct diagnostic value in the assessment of surface integrity. None of the 3D

  6. Optical Generation of Single- or Two-Mode Excited Entangled Coherent States

    Institute of Scientific and Technical Information of China (English)

    REN Zhen-Zhong; JING Hui; ZHANG Xian-Zhou


    With nonlinear Mach-Zehnder interferometer (NLMZI) and a type-Ⅰ beta-barium borate (BBO) crystal, we optically generate single-mode excited entangled coherent states. This scheme can be easily generalized to generate two-mode excited entangled coherent states. We simply analyse different influences of single- and two-mode photon excitations on entangled coherent states.

  7. Improvement of tissue analysis and classification using optical coherence tomography combined with Raman spectroscopy (United States)

    Liu, Chih-Hao; Qi, Ji; Lu, Jing; Wang, Shang; Wu, Chen; Shih, Wei-Chuan; Larin, Kirill V.


    Optical coherence tomography (OCT) is an optical imaging technique that is capable of performing high-resolution (approaching the histopathology level) and real-time imaging of tissues without use of contrast agents. Based on these advantages, the pathological features of tumors (in micro scale) can be identified during resection surgery. However, the accuracy of tumor margin prediction still needs to be enhanced for assisting the judgment of surgeons. In this regard, we present a two-dimensional computational method for advanced tissue analysis and characterization based on optical coherence tomography (OCT) and Raman spectroscopy (RS). The method combines the slope of OCT intensity signal and the Principal component (PC) of RS, and relies on the tissue optical attenuation and chemical ingredients for the classification of tissue types. Our pilot experiments were performed on mouse kidney, liver and small intestine. Results demonstrate the improvement of the tissue differentiation compared with the analysis only based on the OCT detection. This combined OCT/RS method is potentially useful as a novel optical biopsy technique for cancer detection.

  8. Optical coherence tomography monitoring of angioplasty balloon inflation in a deployment tester (United States)

    Azarnoush, Hamed; Vergnole, Sébastien; Bourezak, Rafik; Boulet, Benoit; Lamouche, Guy


    We present an innovative integration of an intravascular optical coherence tomography probe into a computerized balloon deployment system to monitor the balloon inflation process. The high-resolution intraluminal imaging of the balloon provides a detailed assessment of the balloon quality and, consequently, a technique to improve the balloon manufacturing process. A custom-built swept-source optical coherence tomography system is used for real-time imaging. A semicompliant balloon with a nominal diameter of 4 mm is fabricated for the experiments. Imaging results correspond to balloon deployment in air and inside an artery phantom. A characterization of the balloon diameter, wall thickness, compliance, and elastic modulus is provided, based on image segmentation. Using the images obtained from the probe pullback, a three-dimensional visualization of the inflated balloon is presented.

  9. New variational image decomposition model for simultaneously denoising and segmenting optical coherence tomography images. (United States)

    Duan, Jinming; Tench, Christopher; Gottlob, Irene; Proudlock, Frank; Bai, Li


    Optical coherence tomography (OCT) imaging plays an important role in clinical diagnosis and monitoring of diseases of the human retina. Automated analysis of optical coherence tomography images is a challenging task as the images are inherently noisy. In this paper, a novel variational image decomposition model is proposed to decompose an OCT image into three components: the first component is the original image but with the noise completely removed; the second contains the set of edges representing the retinal layer boundaries present in the image; and the third is an image of noise, or in image decomposition terms, the texture, or oscillatory patterns of the original image. In addition, a fast Fourier transform based split Bregman algorithm is developed to improve computational efficiency of solving the proposed model. Extensive experiments are conducted on both synthesised and real OCT images to demonstrate that the proposed model outperforms the state-of-the-art speckle noise reduction methods and leads to accurate retinal layer segmentation.

  10. Modeling of coherent ultrafast magneto-optical experiments: Light-induced molecular mean-field model

    Energy Technology Data Exchange (ETDEWEB)

    Hinschberger, Y. [Instituto de Física dos Materiais da Universidade do Porto, Departamento de Física et Astronomia, Rua do campo Alegre, 687, 4169-007 Porto (Portugal); Hervieux, P.-A. [Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504 BP 43 - F-67034 Strasbourg Cedex 2 (France)


    We present calculations which aim to describe coherent ultrafast magneto-optical effects observed in time-resolved pump-probe experiments. Our approach is based on a nonlinear semi-classical Drude-Voigt model and is used to interpret experiments performed on nickel ferromagnetic thin film. Within this framework, a phenomenological light-induced coherent molecular mean-field depending on the polarizations of the pump and probe pulses is proposed whose microscopic origin is related to a spin-orbit coupling involving the electron spins of the material sample and the electric field of the laser pulses. Theoretical predictions are compared to available experimental data. The model successfully reproduces the observed experimental trends and gives meaningful insight into the understanding of magneto-optical rotation behavior in the ultrafast regime. Theoretical predictions for further experimental studies are also proposed.

  11. Phase-referenced Doppler optical coherence tomography in scattering media. (United States)

    Pedersen, Cameron J; Yazdanfar, Siavash; Westphal, Volker; Rollins, Andrew M


    We present a fiber-based, low-coherence interferometer that significantly reduces phase noise by incorporating a second, narrowband, continuous-wave light source as a phase reference. By incorporating this interferometer into a Doppler OCT system, we demonstrate significant velocity noise reduction in reflective and scattering samples using processing techniques amenable to real-time implementation. We also demonstrate 90% suppression of velocity noise in a flow phantom.

  12. Comment on "Spatial Coherence and Optical Beam Shifts"

    CERN Document Server

    Wang, Li-Gang; Zubairy, M Suhail


    This comment is to show that our simulation data, based on our theory and method in Ref. [J. Phys. B 41, 055401 (2008)], are also in agreement with the experimental data presented for $D_{p}-D_{s}$ in Ref. [Phys. Rev. Lett. \\textbf{109}, 213901 (2012)]. We also demonstrate how to show the effect of spatial coherence on the GH shifts in this comment, therefore we disagree with the claims in Ref. [Phys. Rev. Lett. \\textbf{109}, 213901 (2012)].

  13. Modern fibre-optic coherent lidars for remote sensing (United States)

    Hill, Chris


    This paper surveys some growth areas in optical sensing that exploit near-IR coherent laser sources and fibreoptic hardware from the telecoms industry. Advances in component availability and performance are promising benefits in several military and commercial applications. Previous work has emphasised Doppler wind speed measurements and wind / turbulence profiling for air safety, with recent sharp increases in numbers of lidar units sold and installed, and with wider recognition that different lidar / radar wavebands can and should complement each other. These advances are also enabling fields such as microDoppler measurement of sub-wavelength vibrations and acoustic waves, including non-lineof- sight acoustic sensing in challenging environments. To shed light on these different applications we review some fundamentals of coherent detection, measurement probe volume, and parameter estimation - starting with familiar similarities and differences between "radar" and "laser radar". The consequences of changing the operating wavelength by three or four orders of magnitude - from millimetric or centimetric radar to a typical fibre-optic lidar working near 1.5 μm - need regular review, partly because of continuing advances in telecoms technology and computing. Modern fibre-optic lidars tend to be less complicated, more reliable, and cheaper than their predecessors; and they more closely obey the textbook principles of easily adjusted and aligned Gaussian beams. The behaviours of noises and signals, and the appropriate processing strategies, are as expected different for the different wavelengths and applications. For example, the effective probe volumes are easily varied (e.g. by translating a fibre facet) through six or eight orders of magnitude; as the average number of contributing scatterers varies, from >1, we should review any assumptions about "many" scatterers and Gaussian statistics. Finally, some much older but still relevant scientific work (by A G Bell, E H

  14. Quantitative optical coherence microscopy for the in situ investigation of the biofilm (United States)

    Meleppat, Ratheesh Kumar; Shearwood, Christopher; Keey, Seah Leong; Matham, Murukeshan Vadakke


    This paper explores the potential of optical coherence microscopy (OCM) for the in situ monitoring of biofilm growth. The quantitative imaging of the early developmental biology of a representative biofilm, Klebsiella pneumonia (KP-1), was performed using a swept source-based Fourier domain OCM system. The growth dynamics of the KP-1 biofilms and their transient response under perturbation was investigated using the enface visualization of microcolonies and their spatial localization. Furthermore, the optical density (OD) and planar density of the biofilms are calculated using an OCM technique and compared with OD and colony forming units measured using standard procedures via the sampling of the flow-cell effluent.

  15. Research on sensor technology of Lamb-wave signal acquisition using optical low-coherence (United States)

    Zhu, Y. K.; Yang, C.; Li, X. W.; Chong, B.


    Non-destructive testing of composite materials is a key technology issue in equipment testing. Among the emerging new testing methods, Lamb-wave technology is getting more and more attention. This paper proposed a sensing method to acquire the Lamb-wave signal in thin plate based on optical low-coherence principles. Methods to acquire Lamb-wave in thin plate using optical low-coherence technology were analyzed, and the technical path of non-contact, high-precision method was chosen. Complete in-line experimental system and methods were designed and built up for testing. A sensor system based on Michelson low-coherence interferometer was set up. The distributed optical fiber sensors were arranged on the top of sample materials for signal detection. Mirrors to enhance reflection intensity were attached on the sample. The phase of sensing arm was modulated by PZT vibration. Then signals were detected and processed by Daubechies10 wavelet and Gabor wavelet. In-line testing of thin plate with features of high-precision and high signal-noise-ratio was realized, which is meaningful to dynamic testing of large-scale structure.

  16. Ultra-fast coherent optical system for active remote sensing applications (United States)

    Datta, Shubhashish; Becker, Don; Joshi, Abhay; Howard, Roy


    Active optical remote sensing has numerous applications including battlefield target recognition and tracking, atmospheric monitoring, structural monitoring, collision avoidance systems, and terrestrial mapping. The maximum propagation distance in LIDAR sensors is limited by the signal attenuation. Sensor range could be improved by increasing the transmitted pulse energy, at the expense of reduced resolution and information bandwidth. Coherent detection can operate at low optical power levels without sacrificing sensor bandwidth. Utilizing a high power LO laser to increase the receiver gain, coherent systems provide shot noise-limited gain thereby increasing the sensing range. To fully exploit high LO powers without incurring performance penalties due to the RIN of the LO, high power handling balanced photodiodes are used. The coherent system has superior dynamic range, bandwidth, and noise performance than small-signal APD-based systems. Coherent detection is a linear process that is sensitive to the amplitude, phase and polarization of the received signal. Therefore, Doppler shifts and vibration signatures can be easily recovered. RF adaptive filtering following photodetection enables channel equalization, atmospheric turbulence compensation, and efficient background light filtering. We demonstrate a coherent optical transmission system using 15mA high power handling balanced photodetectors. This system has an IF linewidth <1Hz, employing a proprietary phase locked loop design. Data is presented for 100ps pulsed transmission. We have demonstrated amplitude and phase modulated 10Gb/s communication links with sensitivities of 132 and 72 photons per bit respectively. Investigations into system performance in the presence of laboratory induced atmospheric turbulence are shown.

  17. Collaborative effects of wavefront shaping and optical clearing agent in optical coherence tomography

    CERN Document Server

    Yu, Hyeonseung; Jo, YoungJu; Lee, KyeoReh; Tuchin, Valery V; Jeong, Yong; Park, YongKeun


    We demonstrate that simultaneous application of optical clearing agents (OCAs) and complex wavefront shaping in optical coherence tomography (OCT) can provide significant enhancement of the penetration depth and imaging quality. OCA reduces optical inhomogeneity of a highly scattering sample, and the wavefront shaping of illumination light controls multiple scattering, resulting in an enhancement of the penetration depth and signal-to-noise ratio. A tissue phantom study shows that concurrent applications of OCA and wavefront shaping successfully operate in OCT imaging. The penetration depth enhancement is further demonstrated for ex vivo mouse ears, revealing hidden structures inaccessible with conventional OCT imaging.

  18. Cellular resolution volumetric in vivo retinal imaging with adaptive optics-optical coherence tomography. (United States)

    Zawadzki, Robert J; Choi, Stacey S; Fuller, Alfred R; Evans, Julia W; Hamann, Bernd; Werner, John S


    Ultrahigh-resolution adaptive optics-optical coherence tomography (UHR-AO-OCT) instrumentation allowing monochromatic and chromatic aberration correction was used for volumetric in vivo retinal imaging of various retinal structures including the macula and optic nerve head (ONH). Novel visualization methods that simplify AO-OCT data viewing are presented, and include co-registration of AO-OCT volumes with fundus photography and stitching of multiple AO-OCT sub-volumes to create a large field of view (FOV) high-resolution volume. Additionally, we explored the utility of Interactive Science Publishing by linking all presented AO-OCT datasets with the OSA ISP software.

  19. High-resolution retinal imaging using adaptive optics and Fourier-domain optical coherence tomography (United States)

    Olivier, Scot S.; Werner, John S.; Zawadzki, Robert J.; Laut, Sophie P.; Jones, Steven M.


    This invention permits retinal images to be acquired at high speed and with unprecedented resolution in three dimensions (4.times.4.times.6 .mu.m). The instrument achieves high lateral resolution by using adaptive optics to correct optical aberrations of the human eye in real time. High axial resolution and high speed are made possible by the use of Fourier-domain optical coherence tomography. Using this system, we have demonstrated the ability to image microscopic blood vessels and the cone photoreceptor mosaic.

  20. High speed all optical Nyquist signal generation and full-band coherent detection. (United States)

    Zhang, Junwen; Yu, Jianjun; Fang, Yuan; Chi, Nan


    Spectrum efficient data transmission is of key interest for high capacity optical communication systems considering the limited available bandwidth. Transmission of the high speed signal with higher-order modulation formats within the Nyquist bandwidth using coherent detection brings attractive performance advantages. However, high speed Nyquist signal generation with high order modulation formats is challenging. Electrical Nyquist pulse generation is restricted by the limited sampling rate and processor capacities of digital-to-analog convertor devices, while the optical Nyquist signals can provide a much higher symbol rate using time domain multiplexing method. However, most optical Nyquist signals are based on direct detection with simple modulation formats. Here we report the first experimental demonstration of high speed all optical Nyquist signal generation based on Sinc-shaped pulse generation and time-division multiplexing with high level modulation format and full-band coherent detection. Our experiments demonstrate a highly flexible and compatible all optical high speed Nyquist signal generation and detection scheme for future fiber communication systems.

  1. Optical coherence tomography segmentation reveals ganglion cell layer pathology after optic neuritis. (United States)

    Syc, Stephanie B; Saidha, Shiv; Newsome, Scott D; Ratchford, John N; Levy, Michael; Ford, E'tona; Crainiceanu, Ciprian M; Durbin, Mary K; Oakley, Jonathan D; Meyer, Scott A; Frohman, Elliot M; Calabresi, Peter A


    Post-mortem ganglion cell dropout has been observed in multiple sclerosis; however, longitudinal in vivo assessment of retinal neuronal layers following acute optic neuritis remains largely unexplored. Peripapillary retinal nerve fibre layer thickness, measured by optical coherence tomography, has been proposed as an outcome measure in studies of neuroprotective agents in multiple sclerosis, yet potential swelling during the acute stages of optic neuritis may confound baseline measurements. The objective of this study was to ascertain whether patients with multiple sclerosis or neuromyelitis optica develop retinal neuronal layer pathology following acute optic neuritis, and to systematically characterize such changes in vivo over time. Spectral domain optical coherence tomography imaging, including automated retinal layer segmentation, was performed serially in 20 participants during the acute phase of optic neuritis, and again 3 and 6 months later. Imaging was performed cross-sectionally in 98 multiple sclerosis participants, 22 neuromyelitis optica participants and 72 healthy controls. Neuronal thinning was observed in the ganglion cell layer of eyes affected by acute optic neuritis 3 and 6 months after onset (P optica, with and without a history of optic neuritis, when compared with healthy controls (P optica and a history of optic neuritis exhibited the greatest reduction in ganglion cell layer thickness. Results from our in vivo longitudinal study demonstrate retinal neuronal layer thinning following acute optic neuritis, corroborating the hypothesis that axonal injury may cause neuronal pathology in multiple sclerosis. Further, these data provide evidence of subclinical disease activity, in both participants with multiple sclerosis and with neuromyelitis optica without a history of optic neuritis, a disease in which subclinical disease activity has not been widely appreciated. No pathology was seen in the inner or outer nuclear layers of eyes with optic

  2. Optical modeling of sunlight by using partially coherent sources in organic solar cells. (United States)

    Alaibakhsh, Hamzeh; Darvish, Ghafar


    We investigate the effects of coherent and partially coherent sources in optical modeling of organic solar cells. Two different organic solar cells are investigated: one without substrate and the other with a millimeter-sized glass substrate. The coherent light absorption is calculated with rigorous coupled-wave analysis. The result of this method is convolved with a distribution function to calculate the partially coherent light absorption. We propose a new formulation to accurately model sunlight as a set of partially coherent sources. In the structure with glass substrate, the accurate sunlight modeling results in the elimination of coherent effects in the thick substrate, but the coherency in other layers is not affected. Using partially coherent sources instead of coherent sources for simulations with sunlight results in a smoother absorption spectrum, but the change in the absorption efficiency is negligible.

  3. Optical coherence tomography findings and retinal changes after vitrectomy for optic disc pit maculopathy

    Directory of Open Access Journals (Sweden)

    Gaurav Sanghi


    Full Text Available Purpose : To study the optical coherence tomography (OCT patterns in optic disc pit maculopathy and retinal changes after vitreous surgery. Materials and Methods : Retrospective review of consecutive cases with optic disc pit maculopathy seen at two tertiary eye institutes from January 2005 to June 2009. Results : Twenty-four eyes of 23 patients are included. The presenting visual acuity ranged from 20/400 to 20/20 (median:20/80. The median age at presentation was 24 years (range, 6-57 years. Optical coherence tomography demonstrated a combination of retinoschisis and outer layer detachment (OLD in 19 (79.17% eyes, OLD only in 3 (12.5% eyes and retinoschisis only in 2 (8.33% eyes. An obvious communication (outer layer hole between the schisis and OLD was seen in 14 (73.68% of the 19 eyes with both features. Of the 21 eyes with retinoschisis, schisis was present in multiple layers in 15 (71.43% and single layer in 6 (28.57% eyes. Eleven eyes underwent pars plana vitrectomy including creation of posterior vitreous detachment (PVD, fluid-air exchange, low intensity laser photocoagulation at the temporal edge of the optic disc pit and non-expansile perfluoropropane gas (14% injection. Five (45.45% of 11 eyes undergoing vitrectomy had complete resolution and 4 (36.36% eyes had partial resolution of maculopathy. Visual acuity improved in 8 (72.72% of 11 eyes. Conclusion : Optical coherence tomography demonstrates multiple layer schisis and outer layer detachment as main features of optic disc pit maculopathy. Vitrectomy with PVD induction, laser photocoagulation and gas tamponade results in anatomical and visual improvement in most cases with optic disc pit maculopathy.

  4. Cancellation of coherent synchrotron radiation kicks with optics balance. (United States)

    Di Mitri, S; Cornacchia, M; Spampinati, S


    Minimizing transverse emittance is essential in linear accelerators designed to deliver very high brightness electron beams. Emission of coherent synchrotron radiation (CSR), as a contributing factor to emittance degradation, is an important phenomenon to this respect. A manner in which to cancel this perturbation by imposing certain symmetric conditions on the electron transport system has been suggested.We first expand on this idea by quantitatively relating the beam Courant-Snyder parameters to the emittance growth and by providing a general scheme of CSR suppression with asymmetric optics, provided it is properly balanced along the line. We present the first experimental evidence of this cancellation with the resultant optics balance of multiple CSR kicks: the transverse emittance of a 500 pC, sub-picosecond, high brightness electron beam is being preserved after the passage through the achromatic transfer line of the FERMI@Elettra free electron laser, and emittance growth is observed when the optics balance is intentionally broken. We finally show the agreement between the theoretical model and the experimental results. This study holds the promise of compact dispersive lines with relatively large bending angles, thus reducing costs for future electron facilities.

  5. Optical Coherence Tomography in Patients with Chiari I Malformation

    Directory of Open Access Journals (Sweden)

    Michele Figus


    Full Text Available Background/Aims. To evaluate optic nerve head with spectral domain optical coherence tomography (OCT in patients with Chiari I malformation (CMI compared to healthy controls. Methods. Cross-sectional study. OCT of the optic nerve head of 22 patients with CMI and 22 healthy controls was quantitatively analyzed. The healthy controls were matched for age and sex with the study population. Mean retinal nerve fiber layer (RNFL thickness was calculated for both eyes; the mean thickness value was also registered for each quadrant and for each subfield of the four quadrants. Results. CMI patients showed a reduction of the RNFL thickness in both eyes. This reduction was more statistically significant (P<0.05 for the inferior quadrant in the right eye and in each quadrant than nasal one in the left eye. Conclusion. A distress of the retinal nerve fibers could explain the observed reduction of the RNFL thickness in patients with CMI; in our series the reduction of the RNFL thickness seems lower when CMI is associated with syringomyelia.

  6. Full-field optical coherence tomography apply in sphere measurements (United States)

    Shi, Wei; Li, Weiwei; li, Juncheng; Wang, Jingyu; Wang, Jianguo


    The geometry of a spherical surface, for example that of a precision optic, is completely determined by the radius -of-curvature at one point and the deviation from the perfect spherical form at all other points of the sphere. Full-field Optical Coherence Tomography (FF-OCT) is a parallel detection OCT technique that utilizes a 2D detector array. This technique avoids mechanical scanning in imaging optics, thereby speeding up the imaging process and enhancing the quality of images. The current paper presents an FF-OCT instrument that is designed to be used in sphere measurement with the principle of multiple delays (MD) OCT to evaluate the curvature and radius of curved objects in single-shot imaging. The optimum combination of the MD principle with the FF-OCT method was evaluated, and the radius of a metal ball was measured with this method. The generated 2n-1 contour lines were obtained by using an MDE with n delays in a single en-face OCT image. This method of measurement, it engaged in the measurement accuracy of spherical and enriches the means of measurement, to make a spherical scan techniques flexible application.

  7. Micro-optical coherence tomography of the mammalian cochlea (United States)

    Iyer, Janani S.; Batts, Shelley A.; Chu, Kengyeh K.; Sahin, Mehmet I.; Leung, Hui Min; Tearney, Guillermo J.; Stankovic, Konstantina M.


    The mammalian cochlea has historically resisted attempts at high-resolution, non-invasive imaging due to its small size, complex three-dimensional structure, and embedded location within the temporal bone. As a result, little is known about the relationship between an individual’s cochlear pathology and hearing function, and otologists must rely on physiological testing and imaging methods that offer limited resolution to obtain information about the inner ear prior to performing surgery. Micro-optical coherence tomography (μOCT) is a non-invasive, low-coherence interferometric imaging technique capable of resolving cellular-level anatomic structures. To determine whether μOCT is capable of resolving mammalian intracochlear anatomy, fixed guinea pig inner ears were imaged as whole temporal bones with cochlea in situ. Anatomical structures such as the tunnel of Corti, space of Nuel, modiolus, scalae, and cell groupings were visualized, in addition to individual cell types such as neuronal fibers, hair cells, and supporting cells. Visualization of these structures, via volumetrically-reconstructed image stacks and endoscopic perspective videos, represents an improvement over previous efforts using conventional OCT. These are the first μOCT images of mammalian cochlear anatomy, and they demonstrate μOCT’s potential utility as an imaging tool in otology research. PMID:27633610

  8. Optical coherence tomography for vulnerability assessment of sandstone. (United States)

    Bemand, Elizabeth; Liang, Haida


    Sandstone is an important cultural heritage material, in both architectural and natural settings, such as neolithic rock art panels. The majority of deterioration effects in porous materials such as sandstone are influenced by the presence and movement of water through the material. The presence of water within the porous network of a material results in changes in the optical coherence tomography signal intensity that can be used to monitor the wetting front of water penetration of dry porous materials at various depths. The technique is able to detect wetting front velocities from 1 cm s(-1) to 10(-6) cm s(-1), covering the full range of hydraulic conductivities likely to occur in natural sandstones from pervious to impervious.

  9. Indications of Optical Coherence Tomography in Keratoplasties: Literature Review

    Directory of Open Access Journals (Sweden)

    Thiago Trindade Nesi


    Full Text Available Optical coherence tomography (OCT of the anterior segment, in particular corneal OCT, has become a reliable tool for the cornea specialist, as it provides the acquisition of digital images at high resolution with a noncontact technology. In penetrating or lamellar keratoplasties, OCT can be used to assess central corneal thickness and pachymetry maps, as well as precise measurements of deep stromal opacities, thereby guiding the surgeon to choose the best treatment option. OCT has also been used to evaluate the keratoplasty postoperative period, for early identification of possible complications, such as secondary glaucoma or donor disc detachments in endothelial keratoplasties. Intraoperatively, OCT can be used to assess stromal bed regularity and transparency in anterior lamellar surgeries, especially for those techniques in which a bare Descemet’s membrane is the goal. The purpose of this paper is to review and discuss the role of OCT as a diagnostic tool in various types of keratoplasties.

  10. Microvascular contrast enhancement in optical coherence tomography using microbubbles (United States)

    Assadi, Homa; Demidov, Valentin; Karshafian, Raffi; Douplik, Alexandre; Vitkin, I. Alex


    Gas microbubbles (MBs) are investigated as intravascular optical coherence tomography (OCT) contrast agents. Agar + intralipid scattering tissue phantoms with two embedded microtubes were fabricated to model vascular blood flow. One was filled with human blood, and the other with a mixture of human blood + MB. Swept-source structural and speckle variance (sv) OCT images, as well as speckle decorrelation times, were evaluated under both no-flow and varying flow conditions. Faster decorrelation times and higher structural and svOCT image contrasts were detected in the presence of MB in all experiments. The effects were largest in the svOCT imaging mode, and uniformly diminished with increasing flow velocity. These findings suggest the feasibility of utilizing MB for tissue hemodynamic investigations and for microvasculature contrast enhancement in OCT angiography.

  11. Optical Coherence Tomography and Raman Spectroscopy of the retina

    Energy Technology Data Exchange (ETDEWEB)

    Evans, J W; Zawadzki, R J; Liu, R; Chan, J; Lane, S; Werner, J S


    Imaging the structure and correlating it with the biochemical content of the retina holds promise for fundamental research and for clinical applications. Optical coherence tomography (OCT) is commonly used to image the 3D structure of the retina and while the added functionality of biochemical analysis afforded by Raman scattering could provide critical molecular signatures for clinicians and researchers, there are many technical challenges to combining these imaging modalities. We present an ex vivo OCT microscope combined with Raman spectroscopy capable of collecting morphological and molecular information about a sample simultaneously. The combined instrument will be used to investigate remaining technical challenges to combine these imaging modalities, such as the laser power levels needed to achieve a Raman signal above the noise level without damaging the sample.

  12. Improving resolution of optical coherence tomography for imaging of microstructures (United States)

    Shen, Kai; Lu, Hui; Wang, James H.; Wang, Michael R.


    Multi-frame superresolution technique has been used to improve the lateral resolution of spectral domain optical coherence tomography (SD-OCT) for imaging of 3D microstructures. By adjusting the voltages applied to ? and ? galvanometer scanners in the measurement arm, small lateral imaging positional shifts have been introduced among different C-scans. Utilizing the extracted ?-? plane en face image frames from these specially offset C-scan image sets at the same axial position, we have reconstructed the lateral high resolution image by the efficient multi-frame superresolution technique. To further improve the image quality, we applied the latest K-SVD and bilateral total variation denoising algorithms to the raw SD-OCT lateral images before and along with the superresolution processing, respectively. The performance of the SD-OCT of improved lateral resolution is demonstrated by 3D imaging a microstructure fabricated by photolithography and a double-layer microfluidic device.

  13. Volumetric (3D) compressive sensing spectral domain optical coherence tomography. (United States)

    Xu, Daguang; Huang, Yong; Kang, Jin U


    In this work, we proposed a novel three-dimensional compressive sensing (CS) approach for spectral domain optical coherence tomography (SD OCT) volumetric image acquisition and reconstruction. Instead of taking a spectral volume whose size is the same as that of the volumetric image, our method uses a sub set of the original spectral volume that is under-sampled in all three dimensions, which reduces the amount of spectral measurements to less than 20% of that required by the Shan-non/Nyquist theory. The 3D image is recovered from the under-sampled spectral data dimension-by-dimension using the proposed three-step CS reconstruction strategy. Experimental results show that our method can significantly reduce the sampling rate required for a volumetric SD OCT image while preserving the image quality.

  14. Spectralis optical coherence tomography findings in Welder′s maculopathy

    Directory of Open Access Journals (Sweden)

    Aniruddha Mahindrakar


    Full Text Available Welder′s maculopathy is a form of photochemical damage to the retina and is typically characterized by involvement of the outer retinal layers. Spectral domain optical coherence tomography (SD-OCT imaging was performed in three eyes of two patients with clinical findings suggestive of Welder′s maculopathy in occupational welders. A faceted foveal lesion characterized clinical examination and the SD-OCT line scans images showed a distinct discontinuity of the photoreceptor inner and outer segment (IS/OS junction. The external limiting membrane (ELM and the retinal pigment epithelial (RPE layer remained intact at the site of IS/OS defect. SD-OCT imaging offers a noninvasive way of evaluating the microstructural changes at the fovea in Welder′s maculopathy.

  15. 4D embryonic cardiography using gated optical coherence tomography (United States)

    Jenkins, M. W.; Rothenberg, F.; Roy, D.; Nikolski, V. P.; Hu, Z.; Watanabe, M.; Wilson, D. L.; Efimov, I. R.; Rollins, A. M.


    Simultaneous imaging of very early embryonic heart structure and function has technical limitations of spatial and temporal resolution. We have developed a gated technique using optical coherence tomography (OCT) that can rapidly image beating embryonic hearts in four-dimensions (4D), at high spatial resolution (10-15 μm), and with a depth penetration of 1.5 - 2.0 mm that is suitable for the study of early embryonic hearts. We acquired data from paced, excised, embryonic chicken and mouse hearts using gated sampling and employed image processing techniques to visualize the hearts in 4D and measure physiologic parameters such as cardiac volume, ejection fraction, and wall thickness. This technique is being developed to longitudinally investigate the physiology of intact embryonic hearts and events that lead to congenital heart defects.

  16. Imaging port wine stains by fiber optical coherence tomography (United States)

    Zhao, Shiyong; Gu, Ying; Xue, Ping; Guo, Jin; Shen, Tingmei; Wang, Tianshi; Huang, Naiyan; Zhang, Li; Qiu, Haixia; Yu, Xin; Wei, Xunbin


    We develop a fiber optical coherence tomography (OCT) system in the clinical utility of imaging port wine stains (PWS). We use our OCT system on 41 patients with PWS to document the difference between PWS skin and contralateral normal skin. The system, which operates at 4 frames/s with axial and transverse resolutions of 10 and 9 μm, respectively, in the skin tissue, can clearly distinguish the dilated dermal blood vessels from normal tissue. We present OCT images of patients with PWS and normal human skin. We obtain the structural parameters, including epidermal thickness and diameter and depth of dilated blood vessels. We demonstrate that OCT may be a useful tool for the noninvasive imaging of PWS. It may help determine the photosensitizer dose and laser parameters in photodynamic therapy for treating port wine stains.

  17. Applications of expectation maximization algorithm for coherent optical communication

    DEFF Research Database (Denmark)

    Carvalho, L.; Oliveira, J.; Zibar, Darko


    In this invited paper, we present powerful statistical signal processing methods, used by machine learning community, and link them to current problems in optical communication. In particular, we will look into iterative maximum likelihood parameter estimation based on expectation maximization...

  18. Coherent control of a strongly driven silicon vacancy optical transition in diamond

    CERN Document Server

    Zhou, Yu; Li, Ke; Xiong, Qihua; Aharonovich, Igor; Gao, Wei-bo


    The ability to prepare, optically read out and coherently control single quantum states is a key requirement for quantum information processing. Optically active solid state emitters have emerged as promising candidates with their prospects for on chip integration as quantum nodes and sources of coherent photons for connecting these nodes. Under strongly driving resonant laser field, such quantum emitter can exhibit quantum behavior such as Autler-Townes splitting and Mollow triplet spectrum. Here we demonstrate coherent control of a strongly driven optical transition in silicon vacancy (SiV) center in diamond. Rapid optical detection of photons enabled the observation of time resolved coherent Rabi oscillations and the Mollow triplet from an optical transition of a single SiV defect. Detection with a probing transition further confirmed Autler-Townes splitting generated by a strong laser field. Coherence time of the emitted photons is shown to be comparable to its lifetime and robust under very strong drivin...


    Directory of Open Access Journals (Sweden)

    Suvarna S. Patil


    Full Text Available Optical cross-connects are one of the most important components in the dense wavelength division multiplexer based optical networks. The crossconnects suffer from crosstalk due to the different wavelength light path channels during the switching process leading to the deterioration in bit error rate (BER and hence in the system performance. This paper presents the study of impact of coherent and incoherent crosstalk and power penalty on the optical cross-connects in WDM Networks. The effect of accumulation of coherent crosstalk at different stages of crossconnect has been also investigated and analyzed for the blocking probabilities. Results of coherent and incoherent crosstalk are compared to identify their impact on the working of the cross-connect. The results show that the crosstalk increases with increase in either the number of wavelengths per fiber or the number of input fibers. The result also illustrates decrease in the interference penalty by correlating the crosstalk contributions with each other at the appropriate phase angle. We show that an acceptable blocking probability due to crosstalk is achievable for active wavelengths in the WDM network. The present study can be used to model the possible number of routing stages in such networks.

  20. Integral ceramic superstructure evaluation using time domain optical coherence tomography (United States)

    Sinescu, Cosmin; Bradu, Adrian; Topala, Florin I.; Negrutiu, Meda Lavinia; Duma, Virgil-Florin; Podoleanu, Adrian G.


    Optical Coherence Tomography (OCT) is a non-invasive low coherence interferometry technique that includes several technologies (and the corresponding devices and components), such as illumination and detection, interferometry, scanning, adaptive optics, microscopy and endoscopy. From its large area of applications, we consider in this paper a critical aspect in dentistry - to be investigated with a Time Domain (TD) OCT system. The clinical situation of an edentulous mandible is considered; it can be solved by inserting 2 to 6 implants. On these implants a mesostructure will be manufactured and on it a superstructure is needed. This superstructure can be integral ceramic; in this case materials defects could be trapped inside the ceramic layers and those defects could lead to fractures of the entire superstructure. In this paper we demonstrate that a TD-OCT imaging system has the potential to properly evaluate the presence of the defects inside the ceramic layers and those defects can be fixed before inserting the prosthesis inside the oral cavity. Three integral ceramic superstructures were developed by using a CAD/CAM technology. After the milling, the ceramic layers were applied on the core. All the three samples were evaluated by a TD-OCT system working at 1300 nm. For two of the superstructures evaluated, no defects were found in the most stressed areas. The third superstructure presented four ceramic defects in the mentioned areas. Because of those defects the superstructure may fracture. The integral ceramic prosthesis was send back to the dental laboratory to fix the problems related to the material defects found. Thus, TD-OCT proved to be a valuable method for diagnosing the ceramic defects inside the integral ceramic superstructures in order to prevent fractures at this level.

  1. Optical coherence tomography of the pulmonary arteries: A systematic review. (United States)

    Jorge, Elisabete; Baptista, Rui; Calisto, João; Faria, Henrique; Monteiro, Pedro; Pan, Manuel; Pêgo, Mariano


    Optical coherence tomography (OCT) is an imaging technique extensively used for visualizing the coronary circulation, where it assists clinical decision-making. Along with the new interventional procedures being introduced for pulmonary vascular disease, there is an increasing need for intravascular imaging of the pulmonary arteries. Additionally, measurements of the wall thickness of the pulmonary arteries of patients with various types of pulmonary hypertension (PH) may provide relevant diagnostic and prognostic information. The aim of this review is to summarize all the available evidence on the use of OCT for imaging the pulmonary bed and to describe a simple protocol for OCT image acquisition. We conducted a systematic review of the literature using electronic reference databases through February 2015 (MEDLINE, Cochrane Library, Web of Knowledge, and references cited in other studies) and the search terms "optical coherence tomography," "pulmonary hypertension," and "pulmonary arteries." Studies in which OCT was used to image the pulmonary vessels were considered for inclusion. We identified 14 studies reporting OCT imaging data from the pulmonary arteries. OCT was able to identify intravascular thrombi in patients with chronic thromboembolic PH (CTEPH), and an increase in vessel wall thickness was found in most patients with PH, compared with the controls. OCT has also been reported to be useful for the selection of balloon size in the setting of balloon pulmonary angioplasty for CTEPH. The main limitations include lack of standardization, little data on outcomes, cost, and the technical limitations involved in visualizing small-diameter (arteries, and may provide additional information in the assessment of patients with PH. Prospective high-quality studies assessing the safety, validity, and clinical impact of OCT imaging for pulmonary vessels are warranted.

  2. Foveal thickness after phacoemulsification as measured by optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Gerasimos Th Georgopoulos


    Full Text Available Gerasimos Th Georgopoulos, Dimitrios Papaconstantinou, Maria Niskopoulou, Marilita Moschos, Ilias Georgalas, Chrysanthi KoutsandreaGlaucoma Department, Medical School, Athens University, Athens, GreeceBackground: Despite a significant body of research, no consistency on postoperative foveal thickness as measured by optical coherence tomography (OCT, can be recorded. The purpose of our study was to evaluate the effect of uncomplicated cataract surgery in the thickness of the retina in the foveal area during the early postoperative period.Methods: In a prospective study, 79 eyes were assessed by OCT, on day 1, and weeks 2 and 4 after uncomplicated phacoemulsification with intraocular lens implantation in the Athens University Clinic. The outcome measure was the thickness of the retina in the foveal area.Results: The thickness of the retina preoperatively is significantly smaller (150.4 ± 18.8 (p < 0.05 than the thickness of the retina on day 1 (171.8 ± 21 and week 2 (159.7 ± 19 and returned to the initial levels on week 4 (152 ± 17.1. The estimated correlation coefficients between preoperative and postoperative thickness of the retina were significant (p < 0.05. Conversely, no association was found between postoperative visual acuity and thickness of the retina, neither between the phacoemulsification energy and retinal thickness. Operation time, although inversely related with postoperative visual acuity, was not associated with the thickness of the retina.Conclusions: Following phacoemulsification, an increase in the foveal thickness was detected in the early postoperative period, quantified and followed up by OCT. The foveal thickness returned to the preoperative level, 1 month following surgery in our study. No association was shown between intraoperative parameters and increased postoperative retinal thickness.Keywords: optical coherence tomography, phacoemulsification, retinal thickness

  3. Optical transistor action by nonlinear coupling of stimulated emission and coherent scattering (United States)

    Andrews, David L.; Bradshaw, David S.


    In the pursuit of improved platforms for computing, communications and internet connectivity, all-optical systems offer excellent prospects for a speed and fidelity of data transmission that will greatly surpass conventional electronics, alongside the anticipated benefits of reduced energy loss. With a diverse range of sources and fiber optical connections already in production, much current effort is being devoted towards forging optical components for signal switching, such as an all-optical transistor. Achievement of the desired characteristics for any practicable device can be expected to depend crucially on the engagement of a strongly nonlinear optical response. The innovative scheme proposed in the present work is based upon a third-order nonlinearity - its effect enhanced by stimulated emission - operating within a system designed to exploit the highly nonlinear response observed at the threshold for laser emission. Here, stimulated emission is strongly driven by coupling to the coherent scattering of a signal input beam whose optical frequency is purposely off-set from resonance. An electrodynamical analysis of the all-optical coupling process shows that the signal beam can significantly modify the kinetics of emission, and so lead to a dramatically enhanced output of resonant radiation. The underlying nonlinear optical mechanism is analyzed, model calculations are performed for realizable three-level laser systems, and the results exhibited graphically. The advantages of implementing this all-optical transistor scheme, compared to several previously envisaged proposals, are then outlined.

  4. On the performance of joint iterative detection and decoding in coherent optical channels with laser frequency fluctuations (United States)

    Castrillón, Mario A.; Morero, Damián A.; Agazzi, Oscar E.; Hueda, Mario R.


    The joint iterative detection and decoding (JIDD) technique has been proposed by Barbieri et al. (2007) with the objective of compensating the time-varying phase noise and constant frequency offset experienced in satellite communication systems. The application of JIDD to optical coherent receivers in the presence of laser frequency fluctuations has not been reported in prior literature. Laser frequency fluctuations are caused by mechanical vibrations, power supply noise, and other mechanisms. They significantly degrade the performance of the carrier phase estimator in high-speed intradyne coherent optical receivers. This work investigates the performance of the JIDD algorithm in multi-gigabit optical coherent receivers. We present simulation results of bit error rate (BER) for non-differential polarization division multiplexing (PDM)-16QAM modulation in a 200 Gb/s coherent optical system that includes an LDPC code with 20% overhead and net coding gain of 11.3 dB at BER = 10-15. Our study shows that JIDD with a pilot rate ⩽ 5 % compensates for both laser phase noise and laser frequency fluctuation. Furthermore, since JIDD is used with non-differential modulation formats, we find that gains in excess of 1 dB can be achieved over existing solutions based on an explicit carrier phase estimator with differential modulation. The impact of the fiber nonlinearities in dense wavelength division multiplexing (DWDM) systems is also investigated. Our results demonstrate that JIDD is an excellent candidate for application in next generation high-speed optical coherent receivers.

  5. Monitoring changes of optical attenuation coefficients of acupuncture points during laser acupuncture by optical coherence tomography (United States)

    Huang, Yimei; Yang, Hongqin; Wang, Yuhua; Zheng, Liqin; Xie, Shusen


    The physical properties of acupuncture point were important to discover the mechanism of acupuncture meridian. In this paper, we used an optical coherence tomography to monitor in vivo the changes of optical attenuation coefficients of Hegu acupuncture point and non-acupuncture point during laser irradiation on Yangxi acupuncture point. The optical attenuation coefficients of Hegu acupuncture point and non-acupuncture point were obtained by fitting the raw data according to the Beer-Lambert's law. The experimental results showed that the optical attenuation coefficient of Hegu acupuncture point decreased during the laser acupuncture, in contrast to a barely changed result in that of non-acupuncture point. The significant change of optical attenuation coefficient of Hegu acupuncture point indicated that there was a correlation between Hegu and Yangxi acupuncture points to some extent.

  6. Towards spectral-domain optical coherence tomography on a silicon chip

    NARCIS (Netherlands)

    Akca, B.I.; Wörhoff, K.; Nguyen, V.D.; Kalkman, J.; Leeuwen, van T.G.; Ridder, de R.M.; Pollnau, M.


    Optical coherence tomography (OCT) is a widely used optical imaging technology, particularly in the medical field, since it can provide non-invasive, sub-micrometer resolution diagnostic images of tissue. Current OCT systems contain optical fibers and free-space optical components which make these i

  7. Coherent Optical Memory with High Storage Efficiency and Large Fractional Delay

    CERN Document Server

    Chen, Yi-Hsin; Wang, I-Chung; Du, Shengwang; Chen, Yong-Fan; Chen, Ying-Cheng; Yu, Ite A


    A high-storage efficiency and long-live quantum memory for photons is an essential component in long-distance quantum communication and optical quantum computation. Here, we report a 78% storage efficiency of light pulses in a cold atomic medium based on the effect of electromagnetically induced transparency (EIT). At 50% storage efficiency, we obtain a fractional delay of 74, which is the best up-to-date record. The classical fidelity of the recalled pulse is better than 90% and nearly independent of the storage time, as confirmed by the direct measurement of phase evolution of the output light pulse with a beat-note interferometer. Such excellent phase coherence between the stored and recalled light pulses suggests that the current result can be readily applied to single photon wave packets. Our work significantly advances the technology of EIT-based optical memory and may find practical applications in long-distance quantum communication and optical quantum computation.

  8. Depth Compensated Spectral Domain Optical Coherence Tomography via Digital Compensation

    CERN Document Server

    Boroomand, Ameneh; Shafiee, Mohammad Javad; Bizheva, Kostadinka; Wong, Alexander


    Spectral Domain Optical Coherence Tomography (SD-OCT) is a well-known imaging modality which allows for \\textit{in-vivo} visualization of the morphology of different biological tissues at cellular level resolutions. The overall SD-OCT imaging quality in terms of axial resolution and Signal-to-Noise Ratio (SNR) degrades with imaging depth, while the lateral resolution degrades with distance from the focal plane. This image quality degradation is due both to the design of the SD-OCT imaging system and the optical properties of the imaged object. Here, we present a novel Depth Compensated SD-OCT (DC-OCT) system that integrates a Depth Compensating Digital Signal Processing (DC-DSP) module to improve the overall imaging quality via digital compensation. The designed DC-DSP module can be integrated to any SD-OCT system and is able to simultaneously compensate for the depth-dependent loss of axial and lateral resolutions, depth-varying SNR, as well as sidelobe artifact for improved imaging quality. The integrated D...

  9. Computationally Efficient Nonlinearity Compensation for Coherent Fiber-Optic Systems

    Institute of Scientific and Technical Information of China (English)

    Likai Zhu; Guifang Li


    Split-step digital backward propagation (DBP) can be combined with coherent detection to compensate for fiber nonlinear impairments. A large number of DBP steps is usually needed for a long-haul fiber system, and this creates a heavy computational load. In a trade-off between complexity and performance, interchannel nonlinearity can be disregarded in order to simplify the DBP algorithm. The number of steps can also be reduced at the expense of performance. In periodic dispersion-managed long-haul transmission systems, optical waveform distortion is dominated by chromatic dispersion. As a result, the nonlinearity of the optical signal repeats in every dispersion period. Because of this periodic behavior, DBP of many fiber spans can be folded into one span. Using this distance-folded DBP method, the required computation for a transoceanic transmission system with full inline dispersion compensation can be reduced by up to two orders of magnitude with negligible penalty. The folded DBP method can be modified to compensate for nonlinearity in fiber links with non-zero residua dispersion per span.

  10. Optical coherence tomography in guided surgery of GI cancer (United States)

    Zagaynova, Elena V.; Abelevich, Alexander I.; Zagaynov, Vladimir E.; Gladkova, Natalia D.; Denisenko, Arkady N.; Feldchtein, Felix I.; Snopova, Ludmila B.; Kutis, Irina S.


    Optical Coherence Tomography (OCT) is a new high spatial resolution, real-time optical imaging modality, known from prior pilot studies for its high sensitivity to invasive cancer. We reported our results in an OCT feasibility study for accurate determination of the proximal border for esophageal carcinoma and the distal border for rectal carcinoma. The OCT study enrolled 19 patients with rectal adenocarcinoma and 24 patients with distal esophageal carcinoma (14 squamous cell carcinomas, 10 adenocarcinomas). During pre-surgery planning endoscopy we performed in vivo OCT imaging of the tumor border at four dial clock axes (12, 3, 6 and 9 o"clock). The OCT border then was marked by an electrocoagulator, or by a methylene blue tattoo. A cold biopsy (from the esophagus) was performed at visual and OCT borders and compared with visual and OCT readings. 27 post-surgery excised specimens were analyzed. OCT borders matched the histopathology in 94% cases in the rectum and 83.3% in the esophagus. In the cases of a mismatch between the OCT and histology borders, a deep tumor invasion occurred in the muscle layer (esophagus, rectum). Because of its high sensitivity to mucosal cancer, OCT can be used for pre-surgery planning and surgery guidance of the proximal border for esophageal carcinoma and the distal border for rectal carcinoma. However, deep invasion in the rectum or esophageal wall has to be controlled by alternative diagnostic modalities.

  11. Optical coherence tomography: imaging architect for dermal microdialysis in psoriasis (United States)

    O'Connell, M.-L.; O'Connor, W.; Ramsay, B.; Guihen, E.; Ho, W. L.; Leahy, M. J.


    Optical coherence tomography (OCT) has been used as part of a ground breaking translational study to shed some light on one of the worlds most prevalent autoimmune diseases; psoriasis. The work successfully integrates the fields of optical imaging, biochemistry and dermatology in conducting a dermal microdialysis (DMD) trial for quantitative histamine assessment amongst a group of psoriasis sufferers. The DMD process involves temporary insertion of microscopic hollow tubes into a layer of skin to measure the levels of histamine and other important biological molecules in psoriasis. For comparison purposes, DMD catheters were implanted into healthy, peri-lesional and lesional skin regions. The catheters' entry and exit points and their precise locations in the epidermal layer of the skin were confirmed using OCT thus obtaining high resolution, wide-field images of the affected skin as well as catheter placement whilst local microdialysis enabled a tissue chemistry profile to be obtained from these three skin regions including histamine, a local immune system activator known to contribute towards itch and inflammation. Together these tools offer a synergistic approach in the clinical assessment of the disease. In addition, OCT delivered a non-invasive and rapid method for analyzing the affected skin architecture.

  12. Effective Linewidth of Semiconductor Lasers for Coherent Optical Data Links

    Directory of Open Access Journals (Sweden)

    Miguel Iglesias Olmedo


    Full Text Available We discuss the implications of using monolithically integrated semiconductor lasers in high capacity optical coherent links suitable for metro applications, where the integration capabilities of semiconductor lasers make them an attractive candidate to reduce transceiver cost. By investigating semiconductor laser frequency noise profiles we show that carrier induced frequency noise plays an important role in system performance. We point out that, when such lasers are employed, the commonly used laser linewidth fails to estimate system performance, and we propose an alternative figure of merit that we name “Effective Linewidth”. We derive this figure of merit analytically, explore it by numerical simulations and experimentally validate our results by transmitting a 28 Gbaud DP-16QAM over an optical link. Our investigations cover the use of semiconductor lasers both in the transmitter side and as a local oscillator at the receiver. The obtained results show that our proposed “effective linewidth” is easy to measure and accounts for frequency noise more accurately, and hence the penalties associated to phase noise in the received signal.

  13. 7th Rochester Conference on Coherence and Quantum Optics

    CERN Document Server

    Mandel, Leonard; Wolf, Emil


    The Seventh Rochester Conference on Coherence and Quantum Optics was held on the campus of the University of Rochester during the four-day period June 7 - 10, 1996. More than 280 scientists from 33 countries participated. This book contains the Proceedings of the meeting. This Conference differed from the previous six in the series in having only a limited number of oral presentations, in order to avoid too many parallel sessions. Another new feature was the introduction of tutorial lectures. Most contributed papers were presented in poster sessions. The Conference was sponsored by the American Physical Society, by the Optical Society of America, by the International Union of Pure and Applied Physics and by the University of Rochester. We wish to express our appreciation to these organizations for their support and we especially extend our thanks to the International Union of Pure and Applied Physics for providing financial assistance to a number of speakers from Third World countries, to enable them to take ...

  14. ƒ(R Gravity, Relic Coherent Gravitons and Optical Chaos

    Directory of Open Access Journals (Sweden)

    Lawrence B. Crowell


    Full Text Available We discuss the production of massive relic coherent gravitons in a particular class of ƒ(R gravity, which arises from string theory, and their possible imprint in the Cosmic Microwave Background. In fact, in the very early Universe, these relic gravitons could have acted as slow gravity waves. They may have then acted to focus the geodesics of radiation and matter. Therefore, their imprint on the later evolution of the Universe could appear as filaments and a domain wall in the Universe today. In that case, the effect on the Cosmic Microwave Background should be analogous to the effect of water waves, which, in focusing light, create optical caustics, which are commonly seen on the bottom of swimming pools. We analyze this important issue by showing how relic massive gravity waves (GWs perturb the trajectories of the Cosmic Microwave Background photons (gravitational lensing by relic GWs. The consequence of the type of physics discussed is outlined by illustrating an amplification of what might be called optical chaos.

  15. Coherent optical control of polarization with a critical metasurface

    CERN Document Server

    Kang, Ming


    We describe the mechanism by which a metamaterial surface can act as an ideal phase-controlled rotatable linear polarizer. With equal-power linearly polarized beams incident on each side of the surface, varying the relative phase rotates the polarization angles of the output beams, while keeping the polarization exactly linear. The explanation is based on coupled-mode theory and the idea of coherent perfect absorption into auxiliary polarization channels. The polarization-rotating behavior occurs at a critical point of the coupled-mode theory, which can be associated with the exceptional point of a parity-time (PT) symmetric effective Hamiltonian.

  16. A joint estimation detection of Glaucoma progression in 3D spectral domain optical coherence tomography optic nerve head images (United States)

    Belghith, Akram; Bowd, Christopher; Weinreb, Robert N.; Zangwill, Linda M.


    Glaucoma is an ocular disease characterized by distinctive changes in the optic nerve head (ONH) and visual field. Glaucoma can strike without symptoms and causes blindness if it remains without treatment. Therefore, early disease detection is important so that treatment can be initiated and blindness prevented. In this context, important advances in technology for non-invasive imaging of the eye have been made providing quantitative tools to measure structural changes in ONH topography, an essential element for glaucoma detection and monitoring. 3D spectral domain optical coherence tomography (SD-OCT), an optical imaging technique, has been commonly used to discriminate glaucomatous from healthy subjects. In this paper, we present a new framework for detection of glaucoma progression using 3D SD-OCT images. In contrast to previous works that the retinal nerve fiber layer (RNFL) thickness measurement provided by commercially available spectral-domain optical coherence tomograph, we consider the whole 3D volume for change detection. To integrate a priori knowledge and in particular the spatial voxel dependency in the change detection map, we propose the use of the Markov Random Field to handle a such dependency. To accommodate the presence of false positive detection, the estimated change detection map is then used to classify a 3D SDOCT image into the "non-progressing" and "progressing" glaucoma classes, based on a fuzzy logic classifier. We compared the diagnostic performance of the proposed framework to existing methods of progression detection.

  17. Phase-locking and coherent power combining of broadband linearly chirped optical waves. (United States)

    Satyan, Naresh; Vasilyev, Arseny; Rakuljic, George; White, Jeffrey O; Yariv, Amnon


    We propose, analyze and demonstrate the optoelectronic phase-locking of optical waves whose frequencies are chirped continuously and rapidly with time. The optical waves are derived from a common optoelectronic swept-frequency laser based on a semiconductor laser in a negative feedback loop, with a precisely linear frequency chirp of 400 GHz in 2 ms. In contrast to monochromatic waves, a differential delay between two linearly chirped optical waves results in a mutual frequency difference, and an acoustooptic frequency shifter is therefore used to phase-lock the two waves. We demonstrate and characterize homodyne and heterodyne optical phase-locked loops with rapidly chirped waves, and show the ability to precisely control the phase of the chirped optical waveform using a digital electronic oscillator. A loop bandwidth of ~ 60 kHz, and a residual phase error variance of locking of two optical paths to a common master waveform, and the ability to electronically control the resultant two-element optical phased array. The results of this work enable coherent power combining of high-power fiber amplifiers-where a rapidly chirping seed laser reduces stimulated Brillouin scattering-and electronic beam steering of chirped optical waves.

  18. Handbook of coherent domain optical methods biomedical diagnostics, environmental and material science

    CERN Document Server


    For the first time in one set of books, coherent-domain optical methods are discussed in the framework of various applications, which are characterized by a strong light scattering. A few chapters describe basic research containing the updated results on coherent and polarized light non-destructive interactions with a scattering medium, in particular, diffraction, interference, and speckle formation at multiple scattering. These chapters allow for understanding coherent-domain diagnostic techniques presented in later chapters. A large portion of Volume I is dedicated to analysis of various aspects of optical coherence tomography (OCT) - a very new and growing field of coherent optics. Two chapters on laser scanning confocal microscopy give insight to recent extraordinary results on in vivo imaging and compare the possibilities and achievements of confocol, excitation multiphoton, and OCT microscopy. This two volume reference contains descriptions of holography, interferometry and optical heterodyning techniqu...

  19. Fast Industrial Inspection of Optical Thin Film Using Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Muhammad Faizan Shirazi


    Full Text Available An application of spectral domain optical coherence tomography (SD-OCT was demonstrated for a fast industrial inspection of an optical thin film panel. An optical thin film sample similar to a liquid crystal display (LCD panel was examined. Two identical SD-OCT systems were utilized for parallel scanning of a complete sample in half time. Dual OCT inspection heads were utilized for transverse (fast scanning, while a stable linear motorized translational stage was used for lateral (slow scanning. The cross-sectional and volumetric images of an optical thin film sample were acquired to detect the defects in glass and other layers that are difficult to observe using visual inspection methods. The rapid inspection enabled by this setup led to the early detection of product defects on the manufacturing line, resulting in a significant improvement in the quality assurance of industrial products.

  20. Fiber-optic polarization diversity detection for rotary probe optical coherence tomography. (United States)

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


    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.

  1. 基于谱域光学相干层析系统中光谱涨落的指纹获取%Spectral Fluctuation Based on Spectral Domain Optical Coherence Tomography for Fingerprint Detection

    Institute of Scientific and Technical Information of China (English)

    鲍文; 丁志华; 王川


    Fingerprint plays a very important role in a criminal case as ' First Evidence' as a result of its specificity and stability. A variety of physical, chemical and optical techniques are available for the enhancement and detection of latent fingerprints. However, these existing techniques show some disadvantages such as harm to fingerprints, potential side effects, remaining trails and so on. Phase sensitive spectral domain optical coherence tomography ( SD-OCT ) for latent fingerprints detection has the advantages of non-contact, non-destructive, high-speed and high-sensitivity, but the results are greatly affected by the surface profile. In case of surface with large fluctuations, it is hard to extract the fingerprint with high contrast. In this paper, a method based on spectral fluctuation from spectral domain optical coherence tomo- graphy is proposed to acquire fingerprints. The proposed method only analyses and deals with the spectral fluctuation without retrieval of phase and depth, hence is simple, fast and unrelated to surface profile. The experiment results demonstrate that using the proposed method satisfied results of fingerprints can be obtained even on undulant surface.%指纹因其特异性和稳定性等特点而被称为"证据之首",在案件侦破中起着极其重要的作用.多种物理学、化学和光学技术都可以用于获取现场遗留的指纹,然而这些方法存在一些缺点,如会对指纹造成破坏、潜在的毒副作用、在现场留有痕迹等.利用谱域光学相干层析(spectral domain optical coherence tomography,简记为SD-OCT)技术进行指纹探测具有非接触、对指纹无损伤和高灵敏度的优势,利用OCT系统的相位敏感性我们可以在低对比条件下再现遗留在物体表面的指纹,但处理结果受指纹所在表面高低起伏影响,使得指纹信息对比度降低,难以被分离和提取.本文提出了一种基于干涉光谱涨落的指纹获取方法,只需对OCT系统得

  2. Imaging human retinal pigment epithelium cells using adaptive optics optical coherence tomography (United States)

    Liu, Zhuolin; Kocaoglu, Omer P.; Turner, Timothy L.; Miller, Donald T.


    Retinal pigment epithelium (RPE) cells are vital to health of the outer retina, but are often compromised in ageing and major ocular diseases that lead to blindness. Early manifestation of RPE disruption occurs at the cellular level, and while biomarkers at this scale hold considerable promise, RPE cells have proven extremely challenging to image in the living human eye. We present a novel method based on optical coherence tomography (OCT) equipped with adaptive optics (AO) that overcomes the associated technical obstacles. The method takes advantage of the 3D resolution of AO-OCT, but more critically sub-cellular segmentation and registration that permit organelle motility to be used as a novel contrast mechanism. With this method, we successfully visualized RPE cells and characterized their 3D reflectance profile in every subject and retinal location (3° and 7° temporal to the fovea) imaged to date. We have quantified RPE packing geometry in terms of cell density, cone-to-RPE ratio, and number of nearest neighbors using Voronoi and power spectra analyses. RPE cell density (cells/mm2) showed no significant difference between 3° (4,892+/-691) and 7° (4,780+/-354). In contrast, cone-to- RPE ratio was significantly higher at 3° (3.88+/-0.52:1) than 7° (2.31+/- 0.23:1). Voronoi analysis also showed most RPE cells have six nearest neighbors, which was significantly larger than the next two most prevalent associations: five and seven. Averaged across the five subjects, prevalence of cells with six neighbors was 51.4+/-3.58% at 3°, and 54.58+/-3.01% at 7°. These results are consistent with histology and in vivo studies using other imaging modalities.

  3. Ultrafast all-optical coherent control of single silicon vacancy colour centres in diamond (United States)

    Becker, Jonas Nils; Görlitz, Johannes; Arend, Carsten; Markham, Matthew; Becher, Christoph


    Complete control of the state of a quantum bit (qubit) is a fundamental requirement for any quantum information processing (QIP) system. In this context, all-optical control techniques offer the advantage of a well-localized and potentially ultrafast manipulation of individual qubits in multi-qubit systems. Recently, the negatively charged silicon vacancy centre (SiV-) in diamond has emerged as a novel promising system for QIP due to its superior spectral properties and advantageous electronic structure, offering an optically accessible Λ-type level system with large orbital splittings. Here, we report on all-optical resonant as well as Raman-based coherent control of a single SiV- using ultrafast pulses as short as 1 ps, significantly faster than the centre's phonon-limited ground state coherence time of about 40 ns. These measurements prove the accessibility of a complete set of single-qubit operations relying solely on optical fields and pave the way for high-speed QIP applications using SiV- centres.

  4. Using swept source optical coherence tomography to monitor wound healing in tissue engineered skin (United States)

    Smith, L. E.; Lu, Z.; Bonesi, M.; Smallwood, R.; Matcher, S. J.; MacNeil, S.


    There is an increasing need for a robust simple to use non-invasive imaging technology for monitoring tissue engineered constructs as they develop. We have applied optical coherence tomography (OCT), a relatively new optical technique, to image tissue engineered constructs. Our aim was to evaluate the use of swept-source optical coherence tomography (SSOCT) to non-invasively image reconstructed skin as it developed over several weeks. The epidermis of the reconstructed skin was readily distinguished from the neodermis when examined with standard histology - a destructive imaging technique - of samples. The development of reconstructed skin based on deepithelialised acellular dermis (DED) was accurately monitored with SS-OCT over three weeks and confirmed with conventional histology. It was also possible to image changes in the epidermis due to the presence of melanoma and the healing of these 3D models after wounding with a scalpel, with or without the addition of a fibrin clot. SS-OCT is proving to be a valuable tool in tissue engineering, showing great promise for the non-invasive imaging of optically turbid tissue engineered constructs, including tissue engineered skin.

  5. Spectral domain optical coherence tomography morphology in optic disc pit associated maculopathy

    Directory of Open Access Journals (Sweden)

    Janusz Michalewski


    Full Text Available Purpose: Our purpose was to study the clinical manifestation and course of optic pit maculopathy using Spectral Domain Optical Coherence Tomography (SD- OCT images. Materials and Methods: We used SD-OCT to examine 20 eyes of 19 patients with a macular detachment in combination with an optic. Results: We observed five different fovea appearances in regard to fluid localization. In five eyes, we recorded changes in the fluid distribution with SD-OCT. In 17/20 eyes, we noted a communication between the perineural and subretinal and/or intraretinal space at the margin of the optic disc. Conclusion: 3-dimensional SD-OCT (3D-SDOCT scans revealed a three-fold connection, between subretinal and intraretinal space, perineural space, and the vitreous cavity. Therefore, we suppose that intraretinal or subretinal fluid in optic pit maculopathy may have both a vitreous and cerebrospinal origin. A membrane, covering the optic nerve was noted in 14 cases. Even if it seems intact in some B-scans, it is not complete in others several micrometers apart. Additionally, we observed fluid accumulation below the margin of the optic disc and hyperreflective porous tissue in the optic disc excavation. Those findings do not influence the course of maculopathy.

  6. Compensation of IQ mismatch in optical PDM-OFDM coherent receivers (United States)

    Chung, Hwan Seok; Chang, Sun Hyok; Kim, Kwangjoon


    The performance enhancements based on Gram-Schmidt orthogonalization procedure (GSOP) for compensating IQ mismatch in coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems are investigated. We analytically explore IQ mismatch in optical OFDM systems and investigate the impacts of phase and amplitude IQ mismatch on required optical signal-to-noise ratio (OSNR) for the different values of data mapping and polarization multiplexing. The impacts of analog-to-digital converter (ADC) resolution and the number of samples in GSOP are also evaluated. The results show that the GSOP operation efficiently compensate IQ mismatch induced performance degradations regardless of the amount of IQ phase mismatch, density of data mapping, and polarization multiplexing.

  7. Phase-coherent frequency comparison of optical clocks using a telecommunication fiber link. (United States)

    Schnatz, Harald; Terra, Osama; Predehl, Katharina; Feldmann, Thorsten; Legero, Thomas; Lipphardt, Burghard; Sterr, Uwe; Grosche, Gesine; Holzwarth, Ronald; Hänsch, Theodor W; Udem, Thomas; Lu, Zehuang H; Wang, Li J; Ertmer, Wolfgang; Friebe, Jan; Pape, Andrè; Rasel, Ernst-M; Riedmann, Mathias; Wübbena, Temmo


    We have explored the performance of 2 "dark fibers" of a commercial telecommunication fiber link for a remote comparison of optical clocks. These fibers establish a network in Germany that will eventually link optical frequency standards at PTB with those at the Institute of Quantum Optics (IQ) at the Leibniz University of Hanover, and the Max Planck Institutes in Erlangen (MPL) and Garching (MPQ). We demonstrate for the first time that within several minutes a phase coherent comparison of clock lasers at the few 10(-15) level can also be accomplished when the lasers are more than 100 km apart. Based on the performance of the fiber link to the IQ, we estimate the expected stability for the link from PTB to MPQ via MPL that bridges a distance of approximately 900 km.

  8. Non-destructive evaluation of delamination growth in glass fiber composites using optical coherence tomography (United States)

    Liu, Ping; Groves, Roger M.; Benedictus, Rinze


    Based on low coherence interferometry, a robust optical coherence tomography (OCT) system has been built. The system was used to monitor the growth of a delamination between the middle layers of a glass fiber composite under a static loading. Firstly specimens of the material used for the spar webs in wind turbines were prepared with an interlaminar crack from free edges. Then they were statically loaded by a customized tensile test stage to extend the delamination length and simultaneously scanned by the OCT system. To process the acquired data, an optimized signal processing algorithm was developed. The cross-sectional images clearly show the microstructure and the crack within the specimen. The 3D crack profiles show the application of OCT to determine the evolution of the crack structure inside the composite material during the propagation of the delamination, for the first time to the best of our knowledge.

  9. Doppler optical coherence microscopy and tomography applied to inner ear mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Page, Scott; Freeman, Dennis M. [Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts (United States); Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts (United States); Ghaffari, Roozbeh [Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts (United States)


    While it is clear that cochlear traveling waves underlie the extraordinary sensitivity, frequency selectivity, and dynamic range of mammalian hearing, the underlying micromechanical mechanisms remain unresolved. Recent advances in low coherence measurement techniques show promise over traditional laser Doppler vibrometry and video microscopy, which are limited by low reflectivities of cochlear structures and restricted optical access. Doppler optical coherence tomography (DOCT) and Doppler optical coherence microscopy (DOCM) both utilize a broadband source to limit constructive interference of scattered light to a small axial depth called a coherence gate. The coherence gate can be swept axially to image and measure sub-nanometer motions of cochlear structures throughout the cochlear partition. The coherence gate of DOCT is generally narrower than the confocal gate of the focusing optics, enabling increased axial resolution (typically 15 μm) within optical sections of the cochlear partition. DOCM, frequently implemented in the time domain, centers the coherence gate on the focal plane, achieving enhanced lateral and axial resolution when the confocal gate is narrower than the coherence gate. We compare these two complementary systems and demonstrate their utility in studying cellular and micromechanical mechanisms involved in mammalian hearing.

  10. Coherent phonon optics in a chip with an electrically controlled active device. (United States)

    Poyser, Caroline L; Akimov, Andrey V; Campion, Richard P; Kent, Anthony J


    Phonon optics concerns operations with high-frequency acoustic waves in solid media in a similar way to how traditional optics operates with the light beams (i.e. photons). Phonon optics experiments with coherent terahertz and sub-terahertz phonons promise a revolution in various technical applications related to high-frequency acoustics, imaging, and heat transport. Previously, phonon optics used passive methods for manipulations with propagating phonon beams that did not enable their external control. Here we fabricate a phononic chip, which includes a generator of coherent monochromatic phonons with frequency 378 GHz, a sensitive coherent phonon detector, and an active layer: a doped semiconductor superlattice, with electrical contacts, inserted into the phonon propagation path. In the experiments, we demonstrate the modulation of the coherent phonon flux by an external electrical bias applied to the active layer. Phonon optics using external control broadens the spectrum of prospective applications of phononics on the nanometer scale.

  11. All-optical differential detection for suppressing multiple-access interference in coherent time-addressed optical CDMA systems. (United States)

    Kim, Sun-Jong; Kim, Tae-Young; Park, Chul; Park, Chang-Soo; Chun, Young


    A novel scheme for suppressing the multiple-access interference (MAI) in coherent time-addressed optical CDMA systems is proposed. This is based on a differential detection using the dual-control NOLM. The basic principle for MAI suppression is described. For experimental demonstration, two encoded channels are constructed and decoded. These decoded signals are sent to the dual-control NOLM and a high autocorrelation peak with suppressed MAI at the output of NOLM is observed. Signal-to-interference ratio is improved by 7 dB.

  12. Donor disc attachment assessment with intraoperative spectral optical coherence tomography during descemet stripping automated endothelial keratoplasty

    Directory of Open Access Journals (Sweden)

    Edward Wylegala


    Full Text Available Optical coherence tomography has already been proven to be useful for pre- and post-surgical anterior eye segment assessment, especially in lamellar keratoplasty procedures. There is no evidence for intraoperative usefulness of optical coherence tomography (OCT. We present a case report of the intraoperative donor disc attachment assessment with spectral-domain optical coherence tomography in case of Descemet stripping automated endothelial keratoplasty (DSAEK surgery combined with corneal incisions. The effectiveness of the performed corneal stab incisions was visualized directly by OCT scan analysis. OCT assisted DSAEK allows the assessment of the accuracy of the Descemet stripping and donor disc attachment.

  13. Design & development of a galvanometer inspired dual beam optical coherence tomography system for flow velocity quantification of the microvasculature


    McElligott-Daly, Susan; Jonathan, E.; Martin J. Leahy


    peer-reviewed This paper reports initial experimentation of a dual beam flow velocity estimation setup based on optical coherence tomography (OCT) for biomedical applications. The proposed work incorporates a low cost switching mechanism (rotating galvanometer mirror) for optical signal discrimination between adjacent fiber channels enabling quasisimultaneous multiple specimen scanning. A cascaded interferometric design is used with two sample output arms orientated in parallel to eacho...

  14. Lagrangian based methods for coherent structure detection

    Energy Technology Data Exchange (ETDEWEB)

    Allshouse, Michael R., E-mail: [Center for Nonlinear Dynamics and Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States); Peacock, Thomas, E-mail: [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)


    There has been a proliferation in the development of Lagrangian analytical methods for detecting coherent structures in fluid flow transport, yielding a variety of qualitatively different approaches. We present a review of four approaches and demonstrate the utility of these methods via their application to the same sample analytic model, the canonical double-gyre flow, highlighting the pros and cons of each approach. Two of the methods, the geometric and probabilistic approaches, are well established and require velocity field data over the time interval of interest to identify particularly important material lines and surfaces, and influential regions, respectively. The other two approaches, implementing tools from cluster and braid theory, seek coherent structures based on limited trajectory data, attempting to partition the flow transport into distinct regions. All four of these approaches share the common trait that they are objective methods, meaning that their results do not depend on the frame of reference used. For each method, we also present a number of example applications ranging from blood flow and chemical reactions to ocean and atmospheric flows.

  15. The use of optical coherence tomography in maxillofacial surgery (United States)

    Al-Obaidi, Mohammed; Tandon, Rahul; Tiwana, Paul


    The ever-evolving medical field continues to trend toward less invasive approaches to the diagnosis and treatment of pathological conditions. Basic sciences research has allowed for improved technologies that are translated to the clinical sciences. Similarly, advancements in imaging modalities continue to improve and their applications become more varied. As such, surgeons and pathologists are able to depend on smaller samples for tissue diagnosis of pathological disease, where once large sections of tissue were needed. Optical coherence tomography (OCT), a high-resolution imaging technique, has been used extensively in different medical fields to improve diagnostic yield. Its use in dental fields, particularly in oral and maxillofacial surgery, remains limited. Our goal is to assess the use of OCT for improving soft tissue analysis and diagnosis, particularly for its applications in the field of oral and maxillofacial surgery. Optical coherence tomography is a modality that uses an optical signal using safe near-infrared light which is reflected off the sub-surface structures. This allows for high-resolution cross-sectional images of the tissue morphology to be obtained. Ophthalmologists have been using OCT to obtain images of the retina to assess for age-related macular degeneration. More recently, OCT has been used by Interventional Cardiology to image coronary arteries, and assess plaque thickness and morphology. This technology is now being investigated in several medical fields as a form of optical biopsy, providing in situ images with high-resolution morphology of tissues. We are particularly interested in its use on epithelial tissues, and therefore performed a literature review on the use of OCT for assessing epithelium. Evaluation of histologically-diagnosed actinic keratosis, for example, was found to correlate well with the imaging discrepancies found on OCT; and the in vivo assessment of atypical keratinocytes was firmly established. Additionally

  16. Ultraslow Helical Optical Bullets and Their Acceleration in Magneto-Optically Controlled Coherent Atomic Media

    CERN Document Server

    Hang, Chao


    We propose a scheme to produce ultraslow (3+1)-dimensional helical optical solitons, alias helical optical bullets, in a resonant three-level $\\Lambda$-type atomic system via quantum coherence. We show that, due to the effect of electromagnetically induced transparency, the helical optical bullets can propagate with an ultraslow velocity up to $10^{-5}$ $c$ ($c$ is the light speed in vacuum) in longitudinal direction and a slow rotational motion (with velocity $10^{-7}$ $c$) in transverse directions. The generation power of such optical bullets can be lowered to microwatt, and their stability can be achieved by using a Bessel optical lattice potential formed by a far-detuned laser field. We also show that the transverse rotational motion of the optical bullets can be accelerated by applying a time-dependent Stern-Gerlach magnetic field. Because of the untraslow velocity in the longitudinal direction, a significant acceleration of the rotational motion of optical bullets may be observed for a very short medium...

  17. Imaging Cutaneous T-Cell Lymphoma with Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Hans Christian Ring


    Full Text Available Aim: To investigate the presentation of a patch-stage cutaneous T-cell lymphoma (CTCL using optical coherence tomography (OCT. Methods: A patient with a patch caused by CTCL was photographed digitally, OCT-scanned and biopsied. A normal skin area adjacent to the patch was OCT-scanned for comparison, but not biopsied. The OCT image and the histological image were compared. Results: The OCT images illustrated a thickened and hyperreflective stratum corneum. OCT also demonstrated several elongated hyporeflective structures in the dermis. The largest structure was measured to have a width of 0.13 mm. A good immediate correlation was found between histology and OCT imaging of the sample. Conclusion: The aetiology of the elongated structures is thought to be lymphomatous infiltrates. Similar findings have been described in ocular lymphoma and may therefore be an important characteristic of cutaneous lymphoma. It may further be speculated that the differences in OCT images may reflect the biological behaviour of the infiltrate. This observation therefore suggests that OCT imaging may be a relevant tool for the in vivo investigation of mycosis fungoides and other CTCLs, but in order to verify these observed patterns in OCT imaging, further investigations will be required.

  18. Optical coherence tomography for the diagnosis of human otitis media (United States)

    Cho, Nam Hyun; Jung, Unsang; Jang, Jeong Hun; Jung, Woonggyu; Kim, Jeehyun; Lee, Sang Heun; Boppart, Stephen A.


    We report the application of Optical Coherence Tomography (OCT) to various types of human cases of otitis media (OM). Whereas conventional diagnostic modalities for OM, including standard and pneumatic otoscopy, are limited to visualizing the surface information of the tympanic membrane (TM), OCT is able to effectively reveal the depth-resolved microstructural below the TM with a very high spatial resolution. With the potential advantage of using OCT for diagnosing different types of OM, we examined in-vivo the use of 840 nm wavelength, and OCT spectral domain OCT (SDOCT) techniques, in several human cases including normal ears, and ears with adhesive and effusion types of OM. Peculiar positions were identified in two-dimensional OCT images of abnormal TMs compared to images of a normal TM. Analysis of A-scan (axial depth-scans) data from these positions could successfully identify unique patterns for different constituents within effusions. These OCT images may not only be used for constructing a database for the diagnosis and classification of OM, but they may also demonstrate the feasibility and advantages for upgrading the current otoscopy techniques.

  19. Retinal Imaging of Infants on Spectral Domain Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Anand Vinekar


    Full Text Available Spectral domain coherence tomography (SD OCT has become an important tool in the management of pediatric retinal diseases. It is a noncontact imaging device that provides detailed assessment of the microanatomy and pathology of the infant retina with a short acquisition time allowing office examination without the requirement of anesthesia. Our understanding of the development and maturation of the infant fovea has been enhanced by SD OCT allowing an in vivo assessment that correlates with histopathology. This has helped us understand the critical correlation of foveal development with visual potential in the first year of life and beyond. In this review, we summarize the recent literature on the clinical applications of SD OCT in studying the pathoanatomy of the infant macula, its ability to detect subclinical features, and its correlation with disease and vision. Retinopathy of prematurity and macular edema have been discussed in detail. The review also summarizes the current status of SD OCT in other infant retinal conditions, imaging the optic nerve, the choroid, and the retinal nerve fibre in infants and children, and suggests future areas of research.

  20. Benefits of optical coherence tomography for imaging of skin diseases

    Directory of Open Access Journals (Sweden)

    Utz S.R.


    Full Text Available Aim: working out the methods of visualization of information obtained during optical coherent tomography in normal skin and in series of inflammatory disorders. Materials and Methods. OCS1300SS (made in Thorlabs, USA was used in which the source of emission of radiation was a super-luminiscent diode with mean wavelength of 1325 nm. 12 patients with different skin conditions and 5 virtually healthy volunteers were examined with ОСТ procedure in OPD and IPD settings. High resolution USG numerical system DUB (TPM GmbH, Germany was used for comparative USG assessment. Results. ОСТ demonstrated considerably more detailed picture of the objects scanned compared to USG investigation. Image obtained with the help of ОСТ contains vital information about sizes of macro-morphological elements, status of vascular elements and their density in different depths of the skin. Conclusion. Additional results obtained from ОСТ of the skin lesions in plane section improves attraction for ОСТ in practical dermatology.

  1. Thrombosis and morphology of plaque rupture using optical coherence tomography

    Institute of Scientific and Technical Information of China (English)

    GUO Jun; CHEN Yun-dai; TIAN Feng; LIU Hong-bin; CHEN Lian; SUN Zhi-jun; REN Yi-hong


    Background Thrombosis following plaque rupture is the main cause of acute coronary syndrome,but not all plaque ruptures lead to thrombosis.There are limited in vivo data on the relationship between the morphology of ruptured plaque and thrombosis.Methods We used optical coherence tomography (OCT) to investigate the morphology of plaque rupture and its relation to coronary artery thrombosis in patients with coronary heart disease.Forty-two patients with coronary artery plaque rupture detected by OCT were divided into two groups (with or without thrombus) and the morphological characteristics of ruptured plaque,including fibrous cap thickness and broken cap site,were recorded.Results The fibrous cap of ruptured plaque with thrombus was significantly thinner compared to caps without thrombus ((57.00±17.00) μm vs.(96.00±48.00) μm; P=0.0076).Conclusions Plaque rupture associated with thrombosis occurs primarily in plaque covered by a thin fibrous cap.Thick fibrous caps are associated with greater stability of ruptured plaque.

  2. Spectral domain optical coherence tomography with dual-balanced detection (United States)

    Bo, En; Liu, Xinyu; Chen, Si; Luo, Yuemei; Wang, Nanshuo; Wang, Xianghong; Liu, Linbo


    We developed a spectral domain optical coherence tomography (SD-OCT) system employing dual-balanced detection (DBD) for direct current term suppression and SNR enhancement, especially for auto-autocorrelation artifacts reduction. The DBD was achieved by using a beam splitter to building a free-space Michelson interferometer, which generated two interferometric spectra with a phase difference of π. These two phase-opposed spectra were guided to the spectrometer through two single mode fibers of the 8 fiber v-groove array and acquired by ultizing the upper two lines of a three-line CCD camera. We rotated this fiber v-groove array by 1.35 degrees to focus two spectra onto the first and second line of the CCD camera. Two spectra were aligned by optimum spectrum matching algorithm. By subtracting one spectrum from the other, this dual-balanced detection system achieved a direct current term suppression of ~30 dB, SNR enhancement of ~3 dB, and auto-autocorrelation artifacts reduction of ~10 dB experimentally. Finally we respectively validated the feasibility and performance of dual-balanced detection by imaging a glass plate and swine corneal tissue ex vivo. The quality of images obtained using dual-balanced detection was significantly improved with regard to the conventional single-detection (SD) images.

  3. Optical coherence tomography for embryonic imaging: a review (United States)

    Raghunathan, Raksha; Singh, Manmohan; Dickinson, Mary E.; Larin, Kirill V.


    Embryogenesis is a highly complex and dynamic process, and its visualization is crucial for understanding basic physiological processes during development and for identifying and assessing possible defects, malformations, and diseases. While traditional imaging modalities, such as ultrasound biomicroscopy, micro-magnetic resonance imaging, and micro-computed tomography, have long been adapted for embryonic imaging, these techniques generally have limitations in their speed, spatial resolution, and contrast to capture processes such as cardiodynamics during embryogenesis. Optical coherence tomography (OCT) is a noninvasive imaging modality with micrometer-scale spatial resolution and imaging depth up to a few millimeters in tissue. OCT has bridged the gap between ultrahigh resolution imaging techniques with limited imaging depth like confocal microscopy and modalities, such as ultrasound sonography, which have deeper penetration but poorer spatial resolution. Moreover, the noninvasive nature of OCT has enabled live imaging of embryos without any external contrast agents. We review how OCT has been utilized to study developing embryos and also discuss advances in techniques used in conjunction with OCT to understand embryonic development.

  4. Ex vivo brain tumor analysis using spectroscopic optical coherence tomography (United States)

    Lenz, Marcel; Krug, Robin; Welp, Hubert; Schmieder, Kirsten; Hofmann, Martin R.


    A big challenge during neurosurgeries is to distinguish between healthy tissue and cancerous tissue, but currently a suitable non-invasive real time imaging modality is not available. Optical Coherence Tomography (OCT) is a potential technique for such a modality. OCT has a penetration depth of 1-2 mm and a resolution of 1-15 μm which is sufficient to illustrate structural differences between healthy tissue and brain tumor. Therefore, we investigated gray and white matter of healthy central nervous system and meningioma samples with a Spectral Domain OCT System (Thorlabs Callisto). Additional OCT images were generated after paraffin embedding and after the samples were cut into 10 μm thin slices for histological investigation with a bright field microscope. All samples were stained with Hematoxylin and Eosin. In all cases B-scans and 3D images were made. Furthermore, a camera image of the investigated area was made by the built-in video camera of our OCT system. For orientation, the backsides of all samples were marked with blue ink. The structural differences between healthy tissue and meningioma samples were most pronounced directly after removal. After paraffin embedding these differences diminished. A correlation between OCT en face images and microscopy images can be seen. In order to increase contrast, post processing algorithms were applied. Hence we employed Spectroscopic OCT, pattern recognition algorithms and machine learning algorithms such as k-means Clustering and Principal Component Analysis.

  5. Screening cervical and oesophageal tissues using optical coherence tomography (United States)

    Erry, Gavin R. G.; Bazant-Hegemark, Florian; Read, Mike D.; Stone, Nicholas


    Optical Coherence Tomography (OCT) is a technique that allows imaging tissue in three spatial dimensions. Such a technique makes it possible to examine the subsurface of the tissue. The depth of penetration into the tissue can be tailored by tuning the wavelength of the light source. While in some cases it is desirable to obtain deep penetration of the sample, when scanning for cancerous changes, it may only be necessary to penetrate the first few hundred micrometres. The use of a shorter wavelength, while decreasing the penetration depth, will improve the resolution of the instrument. While images from OCT systems contain speckle and other artefacts, there are methods of evaluating the information by using image processing techniques. Of particular interest is the scattering coefficient that can be derived from the OCT data. Using discriminant techniques on the scattering data (such as principal components analysis), gives a sensitive way of differentiating between changes in structure in the tissue. An extensive data collection was performed on cervical tissue using samples that ranged from normal to invasive cancer. The histopathology of each sample was gathered and was classified from normal to cancer. The scattering profiles of the data were averaged and gradient analysis was performed, showing that for small distances into the sample there is a significant difference between scattering profiles between cancerous and normal tissue. PCA was also performed on the data showing grouping into various stages of cancer.

  6. Towards quantitative analysis of retinal features in optical coherence tomography. (United States)

    Baroni, Maurizio; Fortunato, Pina; La Torre, Agostino


    The purpose of this paper was to propose a new computer method for quantitative evaluation of representative features of the retina using optical coherence tomography (OCT). A multi-step approach was devised and positively tested for segmentation of the three main retinal layers: the vitreo-retinal interface and the inner and outer retina. Following a preprocessing step, three regions of interest were delimited. Significant peaks corresponding to high and low intensity strips were located along the OCT A-scan lines and accurate boundaries between different layers were obtained by maximizing an edge likelihood function. For a quantitative description, thickness measurement, densitometry, texture and curvature analyses were performed. As a first application, the effect of intravitreal injection of triamcinolone acetonide (IVTA) for the treatment of vitreo-retinal interface syndrome was evaluated. Almost all the parameters, measured on a set of 16 pathologic OCT images, were statistically different before and after IVTA injection (pvitreo-retinal interface and in the inner retinal layers. Texture parameters in the inner and outer retinal layers significantly correlated with the visual acuity restoration. According to these findings an IVTA injection might be considered a possible alternative to surgery for selected patients. In conclusion, the proposed approach appeared to be a promising tool for the investigation of tissue changes produced by pathology and/or therapy.

  7. Analysis of Craniocardiac Malformations in Xenopus using Optical Coherence Tomography (United States)

    Deniz, Engin; Jonas, Stephan; Hooper, Michael; N. Griffin, John; Choma, Michael A.; Khokha, Mustafa K.


    Birth defects affect 3% of children in the United States. Among the birth defects, congenital heart disease and craniofacial malformations are major causes of mortality and morbidity. Unfortunately, the genetic mechanisms underlying craniocardiac malformations remain largely uncharacterized. To address this, human genomic studies are identifying sequence variations in patients, resulting in numerous candidate genes. However, the molecular mechanisms of pathogenesis for most candidate genes are unknown. Therefore, there is a need for functional analyses in rapid and efficient animal models of human disease. Here, we coupled the frog Xenopus tropicalis with Optical Coherence Tomography (OCT) to create a fast and efficient system for testing craniocardiac candidate genes. OCT can image cross-sections of microscopic structures in vivo at resolutions approaching histology. Here, we identify optimal OCT imaging planes to visualize and quantitate Xenopus heart and facial structures establishing normative data. Next we evaluate known human congenital heart diseases: cardiomyopathy and heterotaxy. Finally, we examine craniofacial defects by a known human teratogen, cyclopamine. We recapitulate human phenotypes readily and quantify the functional and structural defects. Using this approach, we can quickly test human craniocardiac candidate genes for phenocopy as a critical first step towards understanding disease mechanisms of the candidate genes. PMID:28195132

  8. Three-dimensional calibration targets for optical coherence tomography (United States)

    Gabriele Sandrian, Michelle; Tomlins, Pete; Woolliams, Peter; Rasakanthan, Janarthanan; Lee, Graham C.; Yang, Anna; Považay, Boris; Alex, Aneesh; Sugden, Kate; Drexler, Wolfgang


    The recent expansion of clinical applications for optical coherence tomography (OCT) is driving the development of approaches for consistent image acquisition. There is a simultaneous need for time-stable, easy-to-use imaging targets for calibration and standardization of OCT devices. We present calibration targets consisting of three-dimensional structures etched into nanoparticle-embedded resin. Spherical iron oxide nanoparticles with a predominant particle diameter of 400 nm were homogeneously dispersed in a two part polyurethane resin and allowed to harden overnight. These samples were then etched using a precision micromachining femtosecond laser with a center wavelength of 1026 nm, 100kHz repetition rate and 450 fs pulse duration. A series of lines in depth were etched, varying the percentage of inscription energy and speed of the translation stage moving the target with respect to the laser. Samples were imaged with a dual wavelength spectral-domain OCT system (λ=800nm, ▵λ~180nm, and λ=1325nm, ▵λ~100nm) and point-spread function of nanoparticles within the target was measured.

  9. Using optical coherence tomography to detect peripheral pulmonary thrombi

    Institute of Scientific and Technical Information of China (English)

    HONG Cheng; WANG Wei; ZHONG Nan-shan; ZENG Guang-qiao; WU Hua


    Background Optical coherence tomography (OCT) is a new imaging technique capable of obtaining high-resolution intravascular images of small vessels and has been widely used in interventional cardiology.However,application of OCT in peripheral pulmonary arteries in patients has been seldom documented.Methods Three patients who were highly suspected peripheral pulmonary arteries thrombi and had undergone CT pulmonary angiography but tested negative for thrombi in peripheral pulmonary arteries were enrolled.Subsequently,OCT imaging was performed in peripheral pulmonary arteries.The patients received more than three-month anticoagulative treatment if thrombi were detected by OCT.Thereafter,OCT re-evaluation of the thrombolized blood vessels detected earlier was performed.The changes of thrombi before and after anticoagulative treatment were compared.Results Three patients underwent OCT imaging of peripheral pulmonary arteries.Thrombi were found in most of imaged vessels in these patients.Red and white thrombi can be differentiated,according to features of the thrombus on OCT images.After anticoagulation treatment,these patients' symptoms and hypoxemia improved.Repeated OCT imaging showed that most thrombi disappeared or became smaller.Conclusion OCT may be used as a potential tool for detecting peripheral pulmonary artery thrombi and differentiating red thrombi from white ones.

  10. The potential of optical coherence tomography for diagnosing meniscal pathology (United States)

    Hang-Yin Ling, Carrie; Pozzi, Antonio; Thieman, Kelley M.; Tonks, Catherine A.; Guo, Shuguang; Xie, Huikai; Horodyski, MaryBeth


    Meniscal tears are often associated with anterior cruciate ligament (ACL) injury and may lead to pain and discomfort in humans. Maximal preservation of meniscal tissue is highly desirable to mitigate the progression of osteoarthritis. Guidelines of which meniscal tears are amenable to repair and what part of damaged tissues should be removed are elusive and lacking consensus. Images of microstructural changes in meniscus would potentially guide the surgeons to manage the meniscal tears better, but the resolution of current diagnostic techniques is limited for this application. In this study, we demonstrated the feasibility of using optical coherence tomography (OCT) for the diagnosis of meniscal pathology. Torn medial menisci were collected from dogs with ACL insufficiency. The torn meniscus was divided into three tissue samples and scanned by OCT and scanning electron microscopy (SEM). OCT and SEM images of torn menisci were compared. Each sample was evaluated for gross and microstructural abnormalities and reduction or loss of birefringence from the OCT images. The abnormalities detected with OCT were described for each type of tear. OCT holds promise in non-destructive and fast assessment of microstructural changes and tissue birefringence of meniscal tears. Future development of intraoperative OCT may help surgeons in the decision making of meniscal treatment.

  11. Marginal integrity evaluation of dental composite using optical coherence tomography (United States)

    Stan, Adrian-Tudor; Cojocariu, Andreea-Codruta; Antal, Anca Adriana; Topala, Florin; Sinescu, Cosmin; Negrutiu, Meda Lavinia; Duma, Virgil-Florin; Podoleanu, Adrian Gh.


    In clinical dental practice it is often difficult or even impossible to distinguish and control interfacial adhesive defects from adhesive restorations using visual inspection or other traditional diagnostic methods. Nonetheless, non-invasive biomedical imaging methods like Optical Coherence Tomography (OCT) may provide a better view in this diagnostic outline. The aim of this study is to explore evaluations of the marginal adaptation of class I resin composites restorations using Time Domain (TD) OCT. Posterior human teeth have been chosen for this study. The teeth were stored in 0.9% physiological saline solution prior to use. A classical round-shaped class I cavity was prepared and cavities were restored with Charisma Diamond composite by Heraeus Kulzer and using a system of etch and rinse boding. The specimens were subjected to water storage and then to thermo-cycling. Three dimensional (3-D) scans of the restoration were obtained using a TD-OCT system centered at a 1300 nm wavelength. Open marginal adaptation at the interfaces and gaps inside the composite resins materials were identified using the proposed method. In conclusion, OCT has numerous advantages which justify its use for in vitro, as well as for in vivo studies. It can therefore be considered for non-invasive and fast detection of gaps at the restoration interface.

  12. Spectral Domain Optical Coherence Tomography Findings in Posterior Microphthalmia

    Directory of Open Access Journals (Sweden)

    Emine Tınkır Kayıtmazbatır


    Full Text Available The retinal spectral domain optical coherence tomography (SD-OCT findings of two posterior microphthalmia cases are presented in this case report. For this purpose, the findings of two siblings aged five and seven years who presented to our clinic with the complain of far-sightedness and high hypermetropia were evaluated. Both cases diagnosed to have posterior microphthalmia demonstrated normal biomicroscopic anterior segment examination and gonioscopy findings and the axial lengths were measured to be shorter than 17mm. The SD-OCT analysis of papillomacular folds detected in fundus examination revealed contribution of only neurosensorial retina. Beneath the retinal fold, we observed bilateral cysts in the intraretinal area in one of the cases and a triangle-shaped hyporeflective space with an apex corresponding to that of the retinal fold in the subretinal area in both cases. SD-OCT is an adjunctive imaging tool for diagnosis and follow-up of degenerative changes in posterior microphthalmia. These changes may be also important for visual prognosis. (Turk J Ophthalmol 2014; 44: 240-2

  13. Optical coherence tomography use in the diagnosis of enamel defects (United States)

    Al-Azri, Khalifa; Melita, Lucia N.; Strange, Adam P.; Festy, Frederic; Al-Jawad, Maisoon; Cook, Richard; Parekh, Susan; Bozec, Laurent


    Molar incisor hypomineralization (MIH) affects the permanent incisors and molars, whose undermineralized matrix is evidenced by lesions ranging from white to yellow/brown opacities to crumbling enamel lesions incapable of withstanding normal occlusal forces and function. Diagnosing the condition involves clinical and radiographic examination of these teeth, with known limitations in determining the depth extent of the enamel defects in particular. Optical coherence tomography (OCT) is an emerging hard and soft tissue imaging technique, which was investigated as a new potential diagnostic method in dentistry. A comparison between the diagnostic potential of the conventional methods and OCT was conducted. Compared to conventional imaging methods, OCT gave more information on the structure of the enamel defects as well as the depth extent of the defects into the enamel structure. Different types of enamel defects were compared, each type presenting a unique identifiable pattern when imaged using OCT. Additionally, advanced methods of OCT image analysis including backscattered light intensity profile analysis and enface reconstruction were performed. Both methods confirmed the potential of OCT in enamel defects diagnosis. In conclusion, OCT imaging enabled the identification of the type of enamel defect and the determination of the extent of the enamel defects in MIH with the advantage of being a radiation free diagnostic technique.

  14. Determination of dental decay rates with optical coherence tomography (United States)

    Freitas, A. Z.; Zezell, D. M.; Mayer, M. P. A.; Ribeiro, A. C.; Gomes, A. S. L.; Vieira, N. D., Jr.


    We report the use of optical coherence tomography (OCT) to detect and quantify demineralization process induced by S. mutans biofilm in third molars human teeth. Artificial lesions were induced by a S. mutans microbiological culture and the samples (N = 50) were divided into groups according to the demineralization time: 3, 5, 7, 9, and 11 days. The OCT system was implemented using a light source delivering an average power of 96 μW in the sample arm, and spectral characteristics allowing 23 μm of axial resolution. The images were produced with lateral scans step of 10 μm and analyzed individually. As a result of the evaluation of theses images, lesion depth was calculated as function of demineralization time. The depth of the lesion in the root dentine increased from 70 μm to 230 μm (corrected by the enamel refraction index, 1.62 @ 856 nm), depending of exposure time. The lesion depth in root dentine was correlated to demineralization time, showing that it follows a geometrical progression like a bacteria growth law.

  15. Quantification of choroidal neovascularization vessel length using optical coherence tomography angiography (United States)

    Gao, Simon S.; Liu, Li; Bailey, Steven T.; Flaxel, Christina J.; Huang, David; Li, Dengwang; Jia, Yali


    Quantification of choroidal neovascularization (CNV) as visualized by optical coherence tomography angiography (OCTA) may have importance clinically when diagnosing or tracking disease. Here, we present an automated algorithm to quantify the vessel skeleton of CNV as vessel length. Initial segmentation of the CNV on en face angiograms was achieved using saliency-based detection and thresholding. A level set method was then used to refine vessel edges. Finally, a skeleton algorithm was applied to identify vessel centerlines. The algorithm was tested on nine OCTA scans from participants with CNV and comparisons of the algorithm's output to manual delineation showed good agreement.

  16. Measurement of the refractive index of human teeth by optical coherence tomography (United States)

    Meng, Zhuo; Yao, X. Steve; Yao, Hui; Liang, Yan; Liu, Tiegen; Li, Yanni; Wang, Guanhua; Lan, Shoufeng


    We describe a novel method based on optical coherence tomography (OCT) for the accurate measurement of the refractive index of in vitro human teeth. We obtain the refractive indices of enamel, dentin, and cementum to be 1.631+/-0.007, 1.540+/-0.013, and 1.582+/-0.010, respectively. The profile of the refractive index is readily obtained via an OCT B scan across a tooth. This method can be used to study the refractive index changes caused by dental decay and therefore has great potential for the clinical diagnosis of early dental caries.

  17. The amplitude and the phase or: Measuring directional and random motion with optical coherence tomography

    NARCIS (Netherlands)

    Weiss, N.M.


    Optical coherence tomography (OCT) uses a low coherence light source and a Michelson interferometer to measure path-length resolved backscatter profiles of samples with micrometer resolution and up to a few millimeters long. The OCT amplitude is typically used to generate images of the sample. Addit

  18. Adaptive GOP structure based on motion coherence (United States)

    Ma, Yanzhuo; Wan, Shuai; Chang, Yilin; Yang, Fuzheng; Wang, Xiaoyu


    Adaptive Group of Pictures (GOP) is helpful for increasing the efficiency of video encoding by taking account of characteristics of video content. This paper proposes a method for adaptive GOP structure selection for video encoding based on motion coherence, which extracts key frames according to motion acceleration, and assigns coding type for each key and non-key frame correspondingly. Motion deviation is then used instead of motion magnitude in the selection of the number of B frames. Experimental results show that the proposed method for adaptive GOP structure selection achieves performance gain of 0.2-1dB over the fixed GOP, and has the advantage of better transmission resilience. Moreover, this method can be used in real-time video coding due to its low complexity.

  19. Semi-coherent optical modelling of thin film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Walder, Cordula; Lacombe, Juergen; Maydell, Karsten von; Agert, Carsten [EWE-Forschungszentrum fuer Energietechnologie e.V., Carl-von-Ossietzky-Strasse 15, 26129 Oldenburg (Germany)


    At NEXT ENERGY the experimental investigation of thin film silicon solar cells is combined with numerical simulations using the software Sentaurus TCAD from Synopsys. We present the results of optical modelling with Sentaurus TCAD based on the one-dimensional semi-coherent optical model by Janez Krc. The idea of this model is that after interacting with a rough interface the incident light is split into a direct coherent part treated as electromagnetic waves and in a diffuse incoherent part treated as light beams. The proportion of either direct or diffuse part is determined by the haze parameter which can be obtained from spectrometer data. In order to describe the scattering effects at rough interfaces the intensities of the diffuse light are scaled with angular distribution functions. These functions are obtained from angle resolved scattering measurements. The optical model will be verified by experimental data and compared to the Raytracer and the Transfer Matrix Model. Furthermore the influence of different angles of incidence and of the spectral dependency on the solar cell performance will be investigated.

  20. Coherent Harmonic Generation using the Elettra Storage-Ring Optical Klystron A Numerical Analysis

    CERN Document Server

    Curbis, F


    Coherent harmonic generation can be obtained by means of frequency up-conversion of a high-power external laser focused into the first undulator of an optical klystron. The standard configuration is based on a single-pass device, where the seed laser is synchronized with an electron beam entering the first undulator of the optical klystron after being accelerated using a linear accelerator. As an alternative, the optical klystron may be installed on a storage ring, where it is normally used as interaction region for an oscillator free-electron laser. In this case, removing the optical cavity and using an external seed, one obtains a configuration which is similar to the standard one but also presents some peculiar characteristics. In this paper we investigate the possibility of harmonic generation using the Elettra storage-ring optical klystron. We explore different experimental set-ups varying the beam energy, the seed characteristics and the strength of the optical-klystron dispersive section. We also study...

  1. Effects of haemodilution on the optical properties of blood during coagulation studied by optical coherence tomography (United States)

    Liu, B.; Liu, Y.; Wei, H.; Yang, X.; Wu, G.; Guo, Z.; Yang, H.; He, Y.; Xie, S.


    We report an investigation of the effects of blood dilution with hypertonic (7.5 %) and normal (0.9 %) saline on its optical properties during coagulation in vitro using optical coherence tomography. The light penetration depth and attenuation coefficient are obtained from the dependences of reflectance on the depth. Normal whole blood has served as the control group. The average coagulation time is equal to 420 +/- 16, 418 +/- 16 and 358 +/- 14 {\\text{s}} with blood volume replacement of 2 %, 11 %, and 20 % by 0.9 % normal saline, respectively. With 2 %, 11% and 20% blood volume replacement with 7.5 % hypertonic saline, the average coagulation time is 422 +/- 17, 1160 +/- 45 and 1730 +/- 69 {\\text{s}}, respectively. For normal whole blood, the average coagulation time amounts to 425 +/- 19 {\\text{s}}. it is shown that dilution with normal saline has a procoagulant effect when it replaces 20 % of blood volume, and hypertonic saline has an anticoagulant effect if it replaces 11 % or more of blood volume. It is concluded that optical coherence tomography is a potential technique to quantify and monitor the liquid - gel transition during the coagulation process of blood diluted by normal and hypertonic saline.

  2. Analysis of parallel optical sampling rate and ADC requirements in digital coherent receivers

    DEFF Research Database (Denmark)

    Lorences Riesgo, Abel; Galili, Michael; Peucheret, Christophe


    We comprehensively assess analog-to-digital converter requirements in coherent digital receiver schemes with parallel optical sampling. We determine the electronic requirements in accordance with the properties of the free running local oscillator.......We comprehensively assess analog-to-digital converter requirements in coherent digital receiver schemes with parallel optical sampling. We determine the electronic requirements in accordance with the properties of the free running local oscillator....

  3. Coherent free space optics communications over the maritime atmosphere with use of adaptive optics for beam wavefront correction. (United States)

    Li, Ming; Cvijetic, Milorad


    We evaluate the performance of the coherent free space optics (FSO) employing quadrature array phase-shift keying (QPSK) modulation over the maritime atmosphere with atmospheric turbulence compensated by use of adaptive optics (AO). We have established a comprehensive FSO channel model for maritime conditions and also made a comprehensive comparison of performance between the maritime and terrestrial atmospheric links. The FSO links are modeled based on the intensity attenuation resulting from scattering and absorption effects, the log-amplitude fluctuations, and the phase distortions induced by turbulence. The obtained results show that the FSO system performance measured by the bit-error-rate (BER) can be significantly improved when the optimization of the AO system is achieved. Also, we find that the higher BER is observed in the maritime FSO channel with atmospheric turbulence, as compared to the terrestrial FSO systems if they experience the same turbulence strength.

  4. Optical coherence tomography assessment and quantification of intracoronary thrombus: Status and perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Porto, Italo, E-mail: [Interventional Cardiology Unit, San Donato Hospital, Arezzo (Italy); Mattesini, Alessio; Valente, Serafina [Interventional Cardiology Unit, Careggi Hospital, Florence (Italy); Prati, Francesco [Interventional Cardiology San Giovanni Hospital, Rome (Italy); CLI foundation (Italy); Crea, Filippo [Department of Cardiovascular Sciences, Catholic University of the Sacred Heart, Rome (Italy); Bolognese, Leonardo [Interventional Cardiology Unit, San Donato Hospital, Arezzo (Italy)


    Coronary angiography is the “golden standard” imaging technique in interventional cardiology and it is still widely used to guide interventions. A major drawback of this technique, however, is that it is inaccurate in the evaluation and quantification of intracoronary thrombus burden, a critical prognosticator and predictor of intraprocedural complications in acute coronary syndromes. The introduction of optical coherence tomography (OCT) holds the promise of overcoming this important limitation, as near-infrared light is uniquely sensitive to hemoglobin, the pigment of red blood cells trapped in the thrombus. This narrative review will focus on the use of OCT for the assessment, evaluation and quantification of intracoronary thrombosis. - Highlights: • Thrombotic burden in acute coronary syndromes Is not adequately evaluated by standard coronary angiography, whereas Optical Coherence Tomography is exquisitely sensitive to the hemoglobin contained in red blood cells and can be used to precisely quantify thrombus. • Both research and clinical applications have been developed using the OCT-based evaluation of thrombus. In particular, whereas precise quantification scores are useful for comparing antithrombotic therapies in randomized trials, both pharmacological and mechanical, the most important practical applications for OCT-based assessment of thrombus are the individuation of culprit lesions in the context of diffuse atheromata in acute coronary syndromes, and the so-called “delayed stenting” strategies. • Improvements in 3D rendering techniques are on the verge of revolutionizing OCT-based thrombus assessment, allowing extremely precise quantification of the thrombotic burden.

  5. Application of optical coherence tomography attenuation imaging for quantification of optical properties in medulloblastoma (United States)

    Vuong, Barry; Skowron, Patryk; Kiehl, Tim-Rasmus; Kyan, Matthew; Garzia, Livia; Genis, Helen; Sun, Cuiru; Taylor, Michael D.; Yang, Victor X. D.


    The hemodynamic environment is known to play a crucial role in the progression, rupture, and treatment of intracranial aneurysms. Currently there is difficulty assessing and measuring blood flow profiles in vivo. An emerging high resolution imaging modality known as split spectrum Doppler optical coherence tomography (ssDOCT) has demonstrated the capability to quantify hemodynamic patterns as well as arterial microstructural changes. In this study, we present a novel in vitro method to acquire precise blood flow patterns within a patient- specific aneurysm silicone flow models using ssDOCT imaging. Computational fluid dynamics (CFD) models were generated to verify ssDOCT results.

  6. Coherence transport through imperfect x-ray optical systems. (United States)

    Nugent, K; Tran, C; Roberts, A


    The latest generation of synchrotron sources, so-called third generation sources, are able to produce copious amounts of coherent radiation. However it has become evident that the experimental systems that have been developed are unable to fully utilize the coherent flux. This has led to a perception that coherence is lost while the radiation is transported down the beamline. However it is well established that the degree of coherence must be preserved, or increased, by an experimental system, and so this apparent "decoherence" must have its origin in the nature of the measurement process. In this paper we use phase space methods to present an argument that the loss of useful coherent flux can be attributed to unresolved speckle in the x-ray beam.

  7. Laparoscopic optical coherence tomographic imaging of human ovarian cancer (United States)

    Hariri, Lida P.; Bonnema, Garret T.; Schmidt, Kathy; Korde, Vrushali; Winkler, Amy M.; Hatch, Kenneth; Brewer, Molly; Barton, Jennifer K.


    Ovarian cancer is the fourth leading cause of cancer-related death among women. If diagnosed at early stages, 5-year survival rate is 94%, but drops to 68% for regional disease and 29% for distant metastasis; only 19% of cases are diagnosed at early, localized stages. Optical coherence tomography is a recently emerging non-destructive imaging technology, achieving high axial resolutions (10-20 µm) at imaging depths up to 2 mm. Previously, we studied OCT in normal and diseased human ovary ex vivo. Changes in collagen were suggested with several images that correlated with changes in collagen seen in malignancy. Areas of necrosis and blood vessels were also visualized using OCT, indicative of an underlying tissue abnormality. We recently developed a custom side-firing laparoscopic OCT (LOCT) probe fabricated for in vivo imaging. The LOCT probe, consisting of a 38 mm diameter handpiece terminated in a 280 mm long, 4.6 mm diameter tip for insertion into the laparoscopic trocar, is capable of obtaining up to 9.5 mm image lengths at 10 µm axial resolution. In this pilot study, we utilize the LOCT probe to image one or both ovaries of 17 patients undergoing laparotomy or transabdominal endoscopy and oophorectomy to determine if OCT is capable of differentiating normal and neoplastic ovary. We have laparoscopically imaged the ovaries of seventeen patients with no known complications. Initial data evaluation reveals qualitative distinguishability between the features of undiseased post-menopausal ovary and the cystic, non-homogenous appearance of neoplastic ovary such as serous cystadenoma and endometroid adenocarcinoma.

  8. Optical coherence tomography of the rat cavernous nerves (United States)

    Fried, Nathaniel M.; Rais-Bahrami, Soroush; Lagoda, Gwen A.; Chuang, Ying; Burnett, Arthur L.; Su, Li-Ming


    Improvements in identification, imaging, and visualization of the cavernous nerves during radical prostatectomy, which are responsible for erectile function, may improve nerve preservation and postoperative potency. Optical coherence tomography (OCT) is capable of real-time, high-resolution, cross-sectional, in vivo tissue imaging. The rat prostate serves as an excellent model for studying the use of OCT for imaging the cavernous nerves, as the rat cavernous nerve is a large, visible, and distinct bundle allowing for easy identification with OCT in addition to histologic confirmation. Imaging was performed with the Niris OCT system and a handheld 8 Fr probe, capable of acquiring real-time images with 11-μm axial and 25-μm lateral resolution in tissue. Open surgical exposure of the prostate was performed on a total of 6 male rats, and OCT images of the prostate, cavernous nerve, pelvic plexus ganglion, seminal vesicle, blood vessels, and periprostatic fat were acquired. Cavernous nerve electrical stimulation with simultaneous intracorporeal pressure measurements was performed to confirm proper identification of the cavernous nerves. The prostate and cavernous nerves were also processed for histologic analysis and further confirmation. Cross-sectional and longitudinal OCT images of the cavernous nerves were acquired and compared with histologic sections. The cavernous nerve and ganglion could be differentiated from the surrounding prostate gland, seminal vesicle, blood vessels, bladder, and fatty tissue. We report preliminary results of OCT images of the rat cavernous nerves with histologic correlation and erectile stimulation measurements, thus providing interpretation of prostate structures as they appear in OCT images.

  9. Optical coherence tomography using the Niris system in otolaryngology (United States)

    Rubinstein, Marc; Armstrong, William B.; Djalilian, Hamid R.; Crumley, Roger L.; Kim, Jason H.; Nguyen, Quoc A.; Foulad, Allen I.; Ghasri, Pedram E.; Wong, Brian J. F.


    Objectives: To determine the feasibility and accuracy of the Niris Optical Coherence Tomography (OCT) system in imaging of the mucosal abnormalities of the head and neck. The Niris system is the first commercially available OCT device for applications outside ophthalmology. Methods: We obtained OCT images of benign, premalignant and malignant lesions throughout the head and neck, using the Niris OCT imaging system (Imalux, Cleveland, OH). This imaging system has a tissue penetration depth of approximately 1-2mm, a scanning range of 2mm and a spatial depth resolution of approximately 10-20μm. Imaging was performed in the outpatient setting and in the operating room using a flexible probe. Results: High-resolution cross-sectional images from the oral cavity, nasal cavity, ears and larynx showed distinct layers and structures such as mucosa layer, basal membrane and lamina propria, were clearly identified. In the pathology images disruption of the basal membrane was clearly shown. Device set-up took approximately 5 minutes and the image acquisition was rapid. The system can be operated by the person performing the exam. Conclusions: The Niris system is non invasive and easy to incorporate into the operating room and the clinic. It requires minimal set-up and requires only one person to operate. The unique ability of the OCT offers high-resolution images showing the microanatomy of different sites. OCT imaging with the Niris device potentially offers an efficient, quick and reliable imaging modality in guiding surgical biopsies, intra-operative decision making, and therapeutic options for different otolaryngologic pathologies and premalignant disease.

  10. Analysis of dental abfractions by optical coherence tomography (United States)

    Demjan, Enikö; Mărcăuţeanu, Corina; Bratu, Dorin; Sinescu, Cosmin; Negruţiu, Meda; Ionita, Ciprian; Topală, Florin; Hughes, Michael; Bradu, Adrian; Dobre, George; Podoleanu, Adrian Gh.


    Aim and objectives. Abfraction is the pathological loss of cervical hard tooth substance caused by biomechanical overload. High horizontal occlusal forces result in large stress concentrations in the cervical region of the teeth. These stresses may be high enough to cause microfractures in the dental hard tissues, eventually resulting in the loss of cervical enamel and dentin. The present study proposes the microstructural characterization of these cervical lesions by en face optical coherence tomography (eFOCT). Material and methods: 31 extracted bicuspids were investigated using eFOCT. 24 teeth derived from patients with active bruxism and occlusal interferences; they presented deep buccal abfractions and variable degrees of occlusal pathological attrition. The other 7 bicuspids were not exposed to occlusal overload and had a normal morphology of the dental crowns. The dental samples were investigated using an eFOCT system operating at 1300 nm (B-scan at 1 Hz and C-scan mode at 2 Hz). The system has a lateral resolution better than 5 μm and a depth resolution of 9 μm in tissue. OCT images were further compared with micro - computer tomography images. Results. The eFOCT investigation of bicuspids with a normal morphology revealed a homogeneous structure of the buccal cervical enamel. The C-scan and B-scan images obtained from the occlusal overloaded bicuspids visualized the wedge-shaped loss of cervical enamel and damage in the microstructure of the underlaying dentin. The high occlusal forces produced a characteristic pattern of large cracks, which reached the tooth surface. Conclusions: eFOCT is a promising imaging method for dental abfractions and it may offer some insight on the etiological mechanism of these noncarious cervical lesions.

  11. Role of Optical Coherence Tomography in Assessing Anterior Chamber Angles (United States)

    Kochupurakal, Reema Thomas; Jha, Kirti Nath; Rajalakshmi, A.R.; Nagarajan, Swathi; Ezhumalai, G.


    Introduction Gonioscopy is the gold standard in assessing anterior chamber angles. However, interobserver variations are common and there is a need for reliable objective method of assessment. Aim To compare the anterior chamber angle by gonioscopy and Spectral Domain Optical Coherence Tomography (SD-OCT) in individuals with shallow anterior chamber. Materials and Methods This comparative observational study was conducted in a rural tertiary multi-speciality teaching hospital. A total of 101 eyes of 54 patients with shallow anterior chamber on slit lamp evaluation were included. Anterior chamber angle was graded by gonioscopy using the shaffer grading system. Angles were also assessed by SD-OCT with Trabecular Iris Angle (TIA) and Angle Opening Distance (AOD). Chi-square test, sensitivity, specificity, positive and negative predictive value to find correlation between OCT parameters and gonioscopy grading. Results Females represented 72.7%. The mean age was 53.93 ±8.24 years and mean anterior chamber depth was 2.47 ± 0.152 mm. Shaffer grade ≤ 2 were identified in 95(94%) superior, 42(41.5%) inferior, 65(64.3%) nasal and 57(56.4%) temporal quadrants. Cut-off values of TIA ≤ 22° and AOD ≤ 290 μm were taken as narrow angles on SD-OCT. TIA of ≤ 22° were found in 88(92.6%) nasal and 87(87%) temporal angles. AOD of ≤ 290 μm was found in 73(76.8%) nasal and 83(83%) temporal quadrants. Sensitivity in detecting narrow angles was 90.7% and 82.2% for TIA and AOD, while specificity was 11.7% and 23.4%, respectively. Conclusion Individuals were found to have narrow angles more with SD-OCT. Sensitivity was high and specificity was low in detecting narrow angles compared to gonioscopy, making it an unreliable tool for screening. PMID:27190851

  12. Frontiers in optical methods nano-characterization and coherent control

    CERN Document Server

    Katayama, Ikufumui; Ohno, Shin-Ya


    This collection of reviews by leading Japanese researchers covers topics like ultrafast optical responses, terahertz and phonon studies, super-sensitive surface and high-pressure spectroscopy, combination of visible and x-ray photonics. Several related areas at the cutting edge of measurement technology and materials science are included. This book is partly based on well-cited review articles in the Japanese language in special volumes of the Journal of the Vacuum Society of Japan.

  13. Optoelectronic specifications of emerging coherent optical solutions for data center interconnect (United States)

    Souza, André L. N.; Rozental, Valery N.; Chiuchiarelli, Andrea; Pivem, Tatiani; Reis, Jacklyn D.; Oliveira, Juliano R. F.


    Emerging short-reach data center interconnect is a scenario wherein the capacity has to be maximized over point- to-point optical links without intermediate optical amplification. Most of the transceiver solutions are based on 100G modules with direct detection modulation. Although these legacy solutions are cost-efficient in a short- term, they are not scalable in a long-term, when the capacity x distance product will become more and more stringent. This paper addresses coherent optical solutions for emerging data center interconnect, with optical transmission reach being limited to around unrepeated 100 km. The main advantage of coherent solutions, when compared to legacy direct detection technologies, is the inherently improved spectral efficiency (e.g. 400 Gb/s channels in a 50 GHz grid) and receiver sensitivity provided with high baudrate (>40 GBd) transceiver modules. In this paper, two technological options for single-carrier optical 400 Gb/s modules are exploited for high capacity links over short reach scenarios: 43 GBd polarization-division-multiplexed (PDM)-64QAM, suitable for a 50-GHz grid; and 64 GBd PDM-16QAM, suitable for a 75-GHz grid. These two solutions are compared in terms of capacity allocated in C band (˜4 THz bandwidth), when considering 50 GHz (80 channels at 400G, 32 Tb/s) and 75 GHz (53 channels with 21.2 Tb/s) grids and back-to-back requirements in terms of optoelectronics (digital-to-analog and analog-to-digital converters, modulators, receivers etc.).

  14. Liquid-level Measurement with Fiber-optic Low Coherence Interferometer:Micrometer-resolution Approach

    Institute of Scientific and Technical Information of China (English)

    YANG Yan-fang; SUN Yu-xing; SUN Chang-sen


    According to the fact that the surface of liquid with low viscosity coefficient is a good reflection plane for a broadband light beam,liquid-level measurement in micrometer resolution is designed based on a fiber-optic low coherence interferometer in Michelson configuration.The wave front of the reflected light beam is well enough to form an interferogram with a beam reflected from an optic mirror mounted on a stepping scanning-motor.The central peak of the interferogram is read as a measure of the liquid level.Experimental results show that this noncontact method can reach a resolution of ±1.25 μm in the measurement range of 86 mm.

  15. Analog CMOS design for optical coherence tomography signal detection and processing. (United States)

    Xu, Wei; Mathine, David L; Barton, Jennifer K


    A CMOS circuit was designed and fabricated for optical coherence tomography (OCT) signal detection and processing. The circuit includes a photoreceiver, differential gain stage and lock-in amplifier based demodulator. The photoreceiver consists of a CMOS photodetector and low noise differential transimpedance amplifier which converts the optical interference signal into a voltage. The differential gain stage further amplifies the signal. The in-phase and quadrature channels of the lock-in amplifier each include an analog mixer and switched-capacitor low-pass filter with an external mixer reference signal. The interferogram envelope and phase can be extracted with this configuration, enabling Doppler OCT measurements. A sensitivity of -80 dB is achieved with faithful reproduction of the interferometric signal envelope. A sample image of finger tip is presented.

  16. Handbook of Coherent-Domain Optical Methods Biomedical Diagnostics, Environmental Monitoring, and Materials Science

    CERN Document Server


    This Handbook provides comprehensive coverage of laser and coherent-domain methods as applied to biomedicine, environmental monitoring, and materials science. Worldwide leaders in these fields describe the fundamentals of light interaction with random media and present an overview of basic research. The latest results on coherent and polarization properties of light scattered by random media, including tissues and blood, speckles formation in multiple scattering media, and other non-destructive interactions of coherent light with rough surfaces and tissues, allow the reader to understand the principles and applications of coherent diagnostic techniques. The expanded second edition has been thoroughly updated with particular emphasis on novel coherent-domain techniques and their applications in medicine and environmental science. Volume 1 describes state-of-the-art methods of coherent and polarization optical imaging, tomography and spectroscopy; diffusion wave spectroscopy; elastic, quasi-elastic and inelasti...

  17. Optical coherence tomography detection of shear wave propagation in MCF7 cell modules (United States)

    Razani, Marjan; Mariampillai, Adrian; Berndl, Elizabeth S. L.; Kiehl, Tim-Rasmus; Yang, Victor X. D.; Kolios, Michael C.


    In this work, we explored the potential of measuring shear wave propagation using Optical Coherence Elastography (OCE) in MCF7 cell modules (comprised of MCF7 cells and collagen) and based on a swept-source optical coherence tomography (OCT) system. Shear waves were generated using a piezoelectric transducer transmitting sine-wave bursts of 400 μs, synchronized with an OCT swept source wavelength sweep imaging system. Acoustic radiation force was applied to the MCF7 cell constructs. Differential OCT phase maps, measured with and without the acoustic radiation force, demonstrate microscopic displacement generated by shear wave propagation in these modules. The OCT phase maps are acquired with a swept-source OCT (SS-OCT) system. We also calculated the tissue mechanical properties based on the propagating shear waves in the MCF7 + collagen phantoms using the Acoustic Radiation Force (ARF) of an ultrasound transducer, and measured the shear wave speed with the OCT phase maps. This method lays the foundation for future studies of mechanical property measurements of breast cancer structures, with applications in the study of breast cancer pathologies.

  18. In vivo optical coherence tomography of stimulus-evoked intrinsic optical signals in mouse retinas (United States)

    Wang, Benquan; Lu, Yiming; Yao, Xincheng


    Intrinsic optical signal (IOS) imaging promises a noninvasive method for advanced study and diagnosis of eye diseases. Before pursuing clinical applications, it is essential to understand anatomic and physiological sources of retinal IOSs and to establish the relationship between IOS distortions and eye diseases. The purpose of this study was designed to demonstrate the feasibility of in vivo IOS imaging of mouse models. A high spatiotemporal resolution spectral domain optical coherence tomography (SD-OCT) was employed for depth-resolved retinal imaging. A custom-designed animal holder equipped with ear bar and bite bar was used to minimize eye movements. Dynamic OCT imaging revealed rapid IOS from the photoreceptor's outer segment immediately after the stimulation delivery, and slow IOS changes were observed from inner retinal layers. Comparative photoreceptor IOS and electroretinography recordings suggested that the fast photoreceptor IOS may be attributed to the early stage of phototransduction before the hyperpolarization of retinal photoreceptor.

  19. Optical Sensing Method for Screening Disease in Melon Seeds by Using Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Jeehyun Kim


    Full Text Available We report a noble optical sensing method to diagnose seed abnormalities using optical coherence tomography (OCT. Melon seeds infected with Cucumber green mottle mosaic virus (CGMMV were scanned by OCT. The cross-sectional sensed area of the abnormal seeds showed an additional subsurface layer under the surface which is not found in normal seeds. The presence of CGMMV in the sample was examined by a blind test (n = 140 and compared by the reverse transcription-polymerase chain reaction. The abnormal layers (n = 40 were quantitatively investigated using A-scan sensing analysis and statistical method. By utilizing 3D OCT image reconstruction, we confirmed the distinctive layers on the whole seeds. These results show that OCT with the proposed data processing method can systemically pick up morphological modification induced by viral infection in seeds, and, furthermore, OCT can play an important role in automatic screening of viral infections in seeds.

  20. EEPN and CD study for coherent optical nPSK and nQAM systems with RF pilot based phase noise compensation. (United States)

    Jacobsen, Gunnar; Xu, Tianhua; Popov, Sergei; Li, Jie; Friberg, Ari T; Zhang, Yimo


    A radio frequency (RF) carrier can be used to mitigate the phase noise impact in n-level PSK and QAM systems. The systems performance is influenced by the use of an RF pilot carrier to accomplish phase noise compensation through complex multiplication in combination with discrete filters to compensate for the chromatic dispersion (CD). We perform a detailed study comparing two filters for the CD compensation namely the fixed frequency domain equalizer (FDE) filter and the adaptive least-mean-square (LMS) filter. The study provides important novel physical insight into the equalization enhanced phase noise (EEPN) influence on the system bit-error-rate (BER) versus optical signal-to-noise-ratio (OSNR) performance. Important results of the analysis are that the FDE filter position relative to the RF carrier phase noise compensation module provides a possibility for choosing whether the EEPN from the Tx or the LO laser influences the system quality. The LMS filter works very inefficiently when placed prior to the RF phase noise compensation stage of the Rx whereas it works much more efficiently and gives almost the same performance as the FDE filter when placed after the RF phase noise compensation stage.

  1. Self-trapping Characteristics of Partially Coherent Optical Beam in Photonic Crystal Fiber under Compton Scattering

    Institute of Scientific and Technical Information of China (English)

    HAO Dong-shan; LI Ji-zhou


    Using the mutually coherent function, the self-trapping of the circle partially coherent optical beam in the total internal reflective photonic crystal fiber(TIRPCF) under Compton scattering is studied.The study shows that the composition of the non-coherent optical beam in the optical spectrum and the diffraction effect are decreased by Compton scattering,and the probability of forming the soliton is greatly increased.The vibration peak value in the propagation,compressed degree,changed cycle,and radius of the soliton are all smaller than those before the scattering,but its coherent radius is larger than that before the scattering.In this propagation,the self-focusing plays a key role.

  2. Optical technologies for extreme-ultraviolet and soft X-ray coherent sources

    Energy Technology Data Exchange (ETDEWEB)

    Canova, Federico [Amplitude Technologies, Evry (France); Poletto, Luca (ed.) [National Research Council, Padova (Italy). Inst. of Photonics and Nanotechnology


    The book reviews the most recent achievements in optical technologies for XUV and X-ray coherent sources. Particular attention is given to free-electron-laser facilities, but also to other sources available at present, such as synchrotrons, high-order laser harmonics and X-ray lasers. The optical technologies relevant to each type of source are discussed. In addition, the main technologies used for photon handling and conditioning, namely multilayer mirrors, adaptive optics, crystals and gratings are explained. Experiments using coherent light received during the last decades a lot of attention for the X-ray regime. Strong efforts were taken for the realization of almost fully coherent sources, e.g. the free-electron lasers, both as independent sources in the femtosecond and attosecond regimes and as seeding sources for free-electron-lasers and X-ray gas lasers. In parallel to the development of sources, optical technologies for photon handling and conditioning of such coherent and intense X-ray beams advanced. New problems were faced for the realization of optical components of beamlines demanding to manage coherent X-ray photons, e.g. the preservation of coherence and time structure of ultra short pulses.

  3. Co-registration of optical coherence tomography and X-ray angiography in percutaneous coronary intervention

    DEFF Research Database (Denmark)

    Hebsgaard, Lasse; Nielsen, Troels Munck; Tu, Shengxian;


    . Computer based online co-registration may aid the target segment identification. Methods The DOCTOR fusion study was a prospective, single arm, observational study including patients admitted for elective PCI. Optical coherence tomography (OCT) was acquired pre-stent implantation for sizing of stents...... to the computer-based co-registration, segments of the target lesion indicated on OCT were left uncovered by stent in 14 patients (70%). Conclusion Computer based online co-registration of OCT and angiography is feasible. Frequent inaccuracies in operator based registration indicate that computer aided co......Background Intracoronary imaging provides accurate lesion delineation and precise measurements for sizing and positioning of coronary stents. During percutaneous coronary intervention (PCI), it may be challenging to identify corresponding segments between intracoronary imaging and angiography...

  4. Quantitative shear wave imaging optical coherence tomography for noncontact mechanical characterization of myocardium (United States)

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


    Optical coherence elastography (OCE) is an emerging low-coherence imaging technique that provides noninvasive assessment of tissue biomechanics with high spatial resolution. Among various OCE methods, the capability of quantitative measurement of tissue elasticity is of great importance for tissue characterization and pathology detection across different samples. Here we report a quantitative OCE technique, termed quantitative shear wave imaging optical coherence tomography (Q-SWI-OCT), which enables noncontact measurement of tissue Young's modulus based on the ultra-fast imaging of the shear wave propagation inside the sample. A focused air-puff device is used to interrogate the tissue with a low-pressure short-duration air stream that stimulates a localized displacement with the scale at micron level. The propagation of this tissue deformation in the form of shear wave is captured by a phase-sensitive OCT system running with the scan of the M-mode imaging over the path of the wave propagation. The temporal characteristics of the shear wave is quantified based on the cross-correlation of the tissue deformation profiles at all the measurement locations, and linear regression is utilized to fit the data plotted in the domain of time delay versus wave propagation distance. The wave group velocity is thus calculated, which results in the quantitative measurement of the Young's modulus. As the feasibility demonstration, experiments are performed on tissuemimicking phantoms with different agar concentrations and the quantified elasticity values with Q-SWI-OCT agree well with the uniaxial compression tests. For functional characterization of myocardium with this OCE technique, we perform our pilot experiments on ex vivo mouse cardiac muscle tissues with two studies, including 1) elasticity difference of cardiac muscle under relaxation and contract conditions and 2) mechanical heterogeneity of the heart introduced by the muscle fiber orientation. Our results suggest the

  5. Agreement of angle closure assessments between gonioscopy, anterior segment optical coherence tomography and spectral domain optical coherence tomography

    Institute of Scientific and Technical Information of China (English)

    Elton; Lik; Tong; Tay; Vernon; Khet; Yau; Yong; Boon; Ang; Lim; Stelson; Sia; Elizabeth; Poh; Ying; Wong; Leonard; Wei; Leon; Yip


    AIM: To determine angle closure agreements between gonioscopy and anterior segment optical coherence tomography(AS-OCT), as well as gonioscopy and spectral domain OCT(SD-OCT). A secondary objective was to quantify inter-observer agreements of AS-OCT and SD-OCT assessments.METHODS: Seventeen consecutive subjects(33 eyes)were recruited from the study hospital’s Glaucoma clinic.Gonioscopy was performed by a glaucomatologist masked to OCT results. OCT images were read independently by 2 other glaucomatologists masked to gonioscopy findings as well as each other’s analyses of OCT images.RESULTS: Totally 84.8% and 45.5% of scleral spurs were visualized in AS-OCT and SD-OCT images respectively(P <0.01). The agreement for angle closure between AS-OCT and gonioscopy was fair at k =0.31(95% confidence interval, CI: 0.03-0.59) and k =0.35(95%CI: 0.07-0.63) for reader 1 and 2 respectively. The agreement for angle closure between SD-OCT and gonioscopy was fair at k =0.21(95% CI: 0.07-0.49) and slight at k =0.17(95% CI: 0.08-0.42) for reader 1 and 2 respectively. The inter-reader agreement for angle closure in AS-OCT images was moderate at 0.51(95% CI: 0.13-0.88). The inter-reader agreement for angle closure in SD-OCT images was slight at 0.18(95% CI: 0.08-0.45).CONCLUSION: Significant proportion of scleral spurs were not visualised with SD-OCT imaging resulting in weaker inter-reader agreements. Identifying other angle landmarks in SD-OCT images will allow more consistent angle closure assessments. Gonioscopy and OCT imaging do not always agree in angle closure assessments but have their own advantages, and should be used together and not exclusively.

  6. Coherence and Optical Emission from Bilayer Exciton Condensates

    Directory of Open Access Journals (Sweden)

    D. W. Snoke


    Full Text Available Experiments aimed at demonstrating Bose-Einstein condensation of excitons in two types of experiments with bilayer structures (coupled quantum wells are reviewed, with an emphasis on the basic effects. Bose-Einstein condensation implies the existence of a macroscopic coherence, also known as off-diagonal long-range order, and proposed tests and past claims for coherence in these excitonic systems are discussed.

  7. Identification of muscle necrosis in the mdx mouse model of Duchenne muscular dystrophy using three-dimensional optical coherence tomography (United States)

    Klyen, Blake R.; Shavlakadze, Thea; Radley-Crabb, Hannah G.; Grounds, Miranda D.; Sampson, David D.


    Three-dimensional optical coherence tomography (3D-OCT) was used to image the structure and pathology of skeletal muscle tissue from the treadmill-exercised mdx mouse model of human Duchenne muscular dystrophy. Optical coherence tomography (OCT) images of excised muscle samples were compared with co-registered hematoxylin and eosin-stained and Evans blue dye fluorescence histology. We show, for the first time, structural 3D-OCT images of skeletal muscle dystropathology well correlated with co-located histology. OCT could identify morphological features of interest and necrotic lesions within the muscle tissue samples based on intrinsic optical contrast. These findings demonstrate the utility of 3D-OCT for the evaluation of small-animal skeletal muscle morphology and pathology, particularly for studies of mouse models of muscular dystrophy.

  8. Quantification of the optical surface reflection and surface roughness of articular cartilage using optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Saarakkala, Simo; Wang Shuzhe; Huang Yanping; Zheng Yongping [Department of Health Technology and Informatics, Hong Kong Polytechnic University, Hong Kong (China)], E-mail:, E-mail:


    Optical coherence tomography (OCT) is a promising new technique for characterizing the structural changes of articular cartilage in osteoarthritis (OA). The calculation of quantitative parameters from the OCT signal is an important step to develop OCT as an effective diagnostic technique. In this study, two novel parameters for the quantification of optical surface reflection and surface roughness from OCT measurements are introduced: optical surface reflection coefficient (ORC), describing the amount of a ratio of the optical reflection from cartilage surface with respect to that from a reference material, and OCT roughness index (ORI) indicating the smoothness of the cartilage surface. The sensitivity of ORC and ORI to detect changes in bovine articular cartilage samples after enzymatic degradations of collagen and proteoglycans using collagenase and trypsin enzymes, respectively, was tested in vitro. A significant decrease (p < 0.001) in ORC as well as a significant increase (p < 0.001) in ORI was observed after collagenase digestion. After trypsin digestion, no significant changes in ORC or ORI were observed. To conclude, the new parameters introduced were demonstrated to be feasible and sensitive to detect typical OA-like degenerative changes in the collagen network. From the clinical point of view, the quantification of OCT measurements is of great interest since OCT probes have been already miniaturized and applied in patient studies during arthroscopy or open knee surgery in vivo. Further studies are still necessary to demonstrate the clinical capability of the introduced parameters for naturally occurring early OA changes in the cartilage.

  9. Quantification of the optical surface reflection and surface roughness of articular cartilage using optical coherence tomography (United States)

    Saarakkala, Simo; Wang, Shu-Zhe; Huang, Yan-Ping; Zheng, Yong-Ping


    Optical coherence tomography (OCT) is a promising new technique for characterizing the structural changes of articular cartilage in osteoarthritis (OA). The calculation of quantitative parameters from the OCT signal is an important step to develop OCT as an effective diagnostic technique. In this study, two novel parameters for the quantification of optical surface reflection and surface roughness from OCT measurements are introduced: optical surface reflection coefficient (ORC), describing the amount of a ratio of the optical reflection from cartilage surface with respect to that from a reference material, and OCT roughness index (ORI) indicating the smoothness of the cartilage surface. The sensitivity of ORC and ORI to detect changes in bovine articular cartilage samples after enzymatic degradations of collagen and proteoglycans using collagenase and trypsin enzymes, respectively, was tested in vitro. A significant decrease (p < 0.001) in ORC as well as a significant increase (p < 0.001) in ORI was observed after collagenase digestion. After trypsin digestion, no significant changes in ORC or ORI were observed. To conclude, the new parameters introduced were demonstrated to be feasible and sensitive to detect typical OA-like degenerative changes in the collagen network. From the clinical point of view, the quantification of OCT measurements is of great interest since OCT probes have been already miniaturized and applied in patient studies during arthroscopy or open knee surgery in vivo. Further studies are still necessary to demonstrate the clinical capability of the introduced parameters for naturally occurring early OA changes in the cartilage.

  10. Handheld non-contact evaluation of fastener flushness and countersink surface profiles using optical coherence tomography (United States)

    Wang, James H.; Wang, Michael R.


    We report the use of spectral domain optical coherence tomography (SD-OCT) for non-contact optical evaluation of fastener flushness and countersink surface profile. Using a handheld galvanometer scanner of only 0.5 lb in weight the SD-OCT can perform line scan surface profile measurement of fastener and countersink without demanding accurate scan center alignment. It demonstrates fast measurement of fastener flushness, radius, slant angle, as well as countersink edge radius and surface angle within 90 ms suitable for handheld operation. With the use of a broadband light source at 840 nm center wavelength and 45 nm spectral bandwidth and a lens of 60 mm focal length, the low coherence interferometry based SD-OCT measurement offers axial depth resolution of 8.5 μm, lateral resolution of 19 μm, and measurement depth of 3.65 mm in the air. Multi-line scans can yield 3D surface profiles of fastener and countersink.

  11. Promoting Conceptual Coherence Within Context-Based Biology Education

    NARCIS (Netherlands)

    Ummels, Micha H J; Kamp, Marcel J A; De Kroon, Hans; Boersma, Kerst Th


    In secondary science education, the learning and teaching of coherent conceptual understanding are often problematic. Context-based education has been proposed as a partial solution to this problem. This study aims to gain insight into the development of conceptual coherence and how context-embedded

  12. Partially coherent X-ray wavefront propagation simulations including grazing-incidence focusing optics. (United States)

    Canestrari, Niccolo; Chubar, Oleg; Reininger, Ruben


    X-ray beamlines in modern synchrotron radiation sources make extensive use of grazing-incidence reflective optics, in particular Kirkpatrick-Baez elliptical mirror systems. These systems can focus the incoming X-rays down to nanometer-scale spot sizes while maintaining relatively large acceptance apertures and high flux in the focused radiation spots. In low-emittance storage rings and in free-electron lasers such systems are used with partially or even nearly fully coherent X-ray beams and often target diffraction-limited resolution. Therefore, their accurate simulation and modeling has to be performed within the framework of wave optics. Here the implementation and benchmarking of a wave-optics method for the simulation of grazing-incidence mirrors based on the local stationary-phase approximation or, in other words, the local propagation of the radiation electric field along geometrical rays, is described. The proposed method is CPU-efficient and fully compatible with the numerical methods of Fourier optics. It has been implemented in the Synchrotron Radiation Workshop (SRW) computer code and extensively tested against the geometrical ray-tracing code SHADOW. The test simulations have been performed for cases without and with diffraction at mirror apertures, including cases where the grazing-incidence mirrors can be hardly approximated by ideal lenses. Good agreement between the SRW and SHADOW simulation results is observed in the cases without diffraction. The differences between the simulation results obtained by the two codes in diffraction-dominated cases for illumination with fully or partially coherent radiation are analyzed and interpreted. The application of the new method for the simulation of wavefront propagation through a high-resolution X-ray microspectroscopy beamline at the National Synchrotron Light Source II (Brookhaven National Laboratory, USA) is demonstrated.

  13. Phase-sensitive multiple reference optical coherence tomography (Conference Presentation) (United States)

    Dsouza, Roshan I.; Subhash, Hrebesh; Neuhaus, Kai; Hogan, Josh; Wilson, Carol; Leahy, Martin


    Multiple reference OCT (MR-OCT) is a recently developed novel time-domain OCT platform based on a miniature reference arm optical delay, which utilizes a single miniature actuator and a partial mirror to generate recirculating optical delay for extended axial-scan range. MR-OCT technology promises to fit into a robust and cost-effective design, compatible with integration into consumer-level devices for addressing wide applications in mobile healthcare and biometry applications. Using conventional intensity based OCT processing techniques, the high-resolution structural imaging capability of MR-OCT has been recently demonstrated for various applications including in vivo human samples. In this study, we demonstrate the feasibility of implementing phase based processing with MR-OCT for various functional applications such as Doppler imaging and sensing of blood vessels, and for tissue vibrography applications. The MR-OCT system operates at 1310nm with a spatial resolution of ~26 µm and an axial scan rate of 600Hz. Initial studies show a displacement-sensitivity of ~20 nm to ~120 nm for the first 1 to 9 orders of reflections, respectively with a mirror as test-sample. The corresponding minimum resolvable velocity for these orders are ~2.3 µm/sec and ~15 µm/sec respectively. Data from a chick chorioallantoic membrane (CAM) model will be shown to demonstrate the feasibility of MR-OCT for imaging in-vivo blood flow.

  14. Optical coherence tomography imaging for evaluating the photo biomodulation effects on tissue regeneration in the oral cavity (United States)

    Gimbel, Craig B.


    Optical Coherence Tomography (OCT) is a noninvasive method for imaging dental microstructure which has the potential of evaluating the health of periodontal tissue. OCT provides an "optical biopsy" of tissue 2-3 mm in depth. Optical biopsy is a measurement of the localized optical properties based on tissue type and pathology. This sixth modality of imaging was pioneered at Lawrence Livermore National Laboratory. OCT is based on the optical scattering signatures within tissue structure. With the use of a broad spectrum bandwidth light source, high resolution images, 10 times the resolution of radiographs, can detect important tissue interfaces within the periodontal sulcus and its' relationship to the attachment apparatus of the tooth. Multiple cross-sectional tomograms can be stacked to create two and three dimensional images providing information as to health of periodontal tissue important to both the clinician and researcher.

  15. Transmission and full-band coherent detection of polarization-multiplexed all-optical Nyquist signals generated by Sinc-shaped Nyquist pulses. (United States)

    Zhang, Junwen; Yu, Jianjun; Chi, Nan


    All optical method is considered as a promising technique for high symbol rate Nyquist signal generation, which has attracted a lot of research interests for high spectral-efficiency and high-capacity optical communication system. In this paper, we extend our previous work and report the fully experimental demonstration of polarization-division multiplexed (PDM) all-optical Nyquist signal generation based on Sinc-shaped Nyquist pulse with advanced modulation formats, fiber-transmission and single-receiver full-band coherent detection. Using this scheme, we have successfully demonstrated the generation, fiber transmission and single-receiver full-band coherent detection of all-optical Nyquist PDM-QPSK and PDM-16QAM signals up to 125-GBaud. 1-Tb/s single-carrier PDM-16QAM signal generation and full-band coherent detection is realized, which shows the advantage and feasibility of the single-carrier all-optical Nyquist signals.

  16. Jones matrix analysis for a polarization-sensitive optical coherence tomography system using fiber-optic components


    Park, B. H.; Pierce, M. C.; Cense, B.; De Boer, MR


    We present an analysis for polarization-sensitive optical coherence tomography that facilitates the unrestricted use of fiber and fiber-optic components throughout an interferometer and yields sample birefringence, diattenuation, and relative optic axis orientation. We use a novel Jones matrix approach that compares the polarization states of light reflected from the sample surface with those reflected from within a biological sample for pairs of depth scans. The incident polarization alterna...

  17. Structural examination of easel paintings with optical coherence tomography. (United States)

    Targowski, Piotr; Iwanicka, Magdalena; Tymińska-Widmer, Ludmiła; Sylwestrzak, Marcin; Kwiatkowska, Ewa A


    Identification of the order, thickness, composition, and possibly the origin of the paint layers forming the structure of a painting, that is, its stratigraphy, is important in confirming its attribution and history as well as planning conservation treatments. The most common method of examination is analysis of a sample collected from the art object, both visually with a microscope and instrumentally through a variety of sophisticated, modern analytical tools. Because of its invasiveness, however, sampling is less than ideally compatible with conservation ethics; it is severely restricted with respect to the amount of material extirpated from the artwork. Sampling is also rather limited in that it provides only very local information. There is, therefore, a great need for a noninvasive method with sufficient in-depth resolution for resolving the stratigraphy of works of art. Optical coherence tomography (OCT) is a noninvasive, noncontact method of optical sectioning of partially transparent objects, with micrometer-level axial resolution. The method utilizes near-infrared light of low intensity (a few milliwatts) to obtain cross-sectional images of various objects; it has been mostly used in medical diagnostics. Through the serial collection of many such images, volume information may be extracted. The application of OCT to the examination of art objects has been in development since 2003. In this Account, we present a short introduction to the technique, briefly discuss the apparatus we use, and provide a paradigm for reading OCT tomograms. Unlike the majority of papers published previously, this Account focuses on one, very specific, use of OCT. We then consider two examples of successful, practical application of the technique. At the request of a conservation studio, the characteristics of inscriptions on two oil paintings, originating from the 18th and 19th centuries, were analyzed. In the first case, it was possible to resolve some questions concerning the

  18. Quantum-coherent coupling of a mechanical oscillator to an optical cavity mode. (United States)

    Verhagen, E; Deléglise, S; Weis, S; Schliesser, A; Kippenberg, T J


    Optical laser fields have been widely used to achieve quantum control over the motional and internal degrees of freedom of atoms and ions, molecules and atomic gases. A route to controlling the quantum states of macroscopic mechanical oscillators in a similar fashion is to exploit the parametric coupling between optical and mechanical degrees of freedom through radiation pressure in suitably engineered optical cavities. If the optomechanical coupling is 'quantum coherent'--that is, if the coherent coupling rate exceeds both the optical and the mechanical decoherence rate--quantum states are transferred from the optical field to the mechanical oscillator and vice versa. This transfer allows control of the mechanical oscillator state using the wide range of available quantum optical techniques. So far, however, quantum-coherent coupling of micromechanical oscillators has only been achieved using microwave fields at millikelvin temperatures. Optical experiments have not attained this regime owing to the large mechanical decoherence rates and the difficulty of overcoming optical dissipation. Here we achieve quantum-coherent coupling between optical photons and a micromechanical oscillator. Simultaneously, coupling to the cold photon bath cools the mechanical oscillator to an average occupancy of 1.7 ± 0.1 motional quanta. Excitation with weak classical light pulses reveals the exchange of energy between the optical light field and the micromechanical oscillator in the time domain at the level of less than one quantum on average. This optomechanical system establishes an efficient quantum interface between mechanical oscillators and optical photons, which can provide decoherence-free transport of quantum states through optical fibres. Our results offer a route towards the use of mechanical oscillators as quantum transducers or in microwave-to-optical quantum links.

  19. Time-frequency analysis in optical coherence tomography for technical objects examination (United States)

    StrÄ kowski, Marcin R.; Kraszewski, Maciej; Trojanowski, Michał; Pluciński, Jerzy


    Optical coherence tomography (OCT) is one of the most advanced optical measurement techniques for complex structure visualization. The advantages of OCT have been used for surface and subsurface defect detection in composite materials, polymers, ceramics, non-metallic protective coatings, and many more. Our research activity has been focused on timefrequency spectroscopic analysis in OCT. It is based on time resolved spectral analysis of the backscattered optical signal delivered by the OCT. The time-frequency method gives spectral characteristic of optical radiation backscattered or backreflected from the particular points inside the tested device. This provides more information about the sample, which are useful for further analysis. Nowadays, the applications of spectroscopic analysis for composite layers characterization or tissue recognition have been reported. During our studies we have found new applications of spectroscopic analysis. We have used this method for thickness estimation of thin films, which are under the resolution of OCT. Also, we have combined the spectroscopic analysis with polarization sensitive OCT (PS-OCT). This approach enables to obtain a multiorder retardation value directly and may become a breakthrough in PS-OCT measurements of highly birefringent media. In this work, we present the time-frequency spectroscopic algorithms and their applications for OCT. Also, the theoretical simulations and measurement validation of this method are shown.

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


    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.