WorldWideScience

Sample records for de-fg03-02na00063 coherent imaging

  1. Partially coherent imaging and spatial coherence wavelets

    CERN Document Server

    Castaneda, R

    2003-01-01

    A description of spatially partially coherent imaging based on the propagation of second order spatial coherence wavelets and marginal power spectra (Wigner distribution functions) is presented. In this dynamics, the spatial coherence wavelets will be affected by the system through its elementary transfer function. The consistency of the model with the both extreme cases of full coherent and incoherent imaging was proved. In the last case we obtained the classical concept of optical transfer function as a simple integral of the elementary transfer function. Furthermore, the elementary incoherent response function was introduced as the Fourier transform of the elementary transfer function. It describes the propagation of spatial coherence wavelets form each object point to each image point through a specific point on the pupil planes. The point spread function of the system was obtained by a simple integral of the elementary incoherent response function.

  2. Coherent imaging without phases

    CERN Document Server

    Moscoso, Miguel; Papanicolaou, George

    2015-01-01

    In this paper we consider narrow band, active array imaging of weak localized scatterers when only the intensities are recorded at an array with N transducers. We consider that the medium is homogeneous and, hence, wave propagation is fully coherent. This work is an extension of our previous paper, where we showed that using linear combinations of intensity-only measurements imaging of localized scatterers can be carried out efficiently using MUSIC or sparsity promoting optimization. Here we show the same strategy can be accomplished with only 3N-2 illuminations, therefore reducing enormously the data acquisition process. Furthermore, we show that in the paraxial regime one can form the images by using six illuminations only. In particular, this paraxial regime includes Fresnel and Fraunhofer diffraction. The key point of this work is that if one controls the illuminations, imaging with intensity-only can be easily reduced to a imaging with phases and, therefore, one can apply standard imaging techniques. Det...

  3. Coherent Scatter Imaging Measurements

    Science.gov (United States)

    Ur Rehman, Mahboob

    In conventional radiography, anatomical information of the patients can be obtained, distinguishing different tissue types, e.g. bone and soft tissue. However, it is difficult to obtain appreciable contrast between two different types of soft tissues. Instead, coherent x-ray scattering can be utilized to obtain images which can differentiate between normal and cancerous cells of breast. An x-ray system using a conventional source and simple slot apertures was tested. Materials with scatter signatures that mimic breast cancer were buried in layers of fat of increasing thickness and imaged. The result showed that the contrast and signal to noise ratio (SNR) remained high even with added fat layers and short scan times.

  4. Coherency matrix formulation for partially coherent imaging to evaluate the degree of coherence for image.

    Science.gov (United States)

    Yamazoe, Kenji

    2012-08-01

    This paper defines a matrix from which coherence property of imaging by partially coherent Koehler illumination is determined. The matrix termed coherency matrix in imaging system is derived by the space average of a product of a column vector and its transpose conjugate where each row of the column vector represents mutually incoherent light. The coherency matrix in imaging system has similar properties to the polarization matrix that is utilized for calculating the light intensity and degree of polarization of polarized light. The coherency matrix in imaging system enables us to calculate not only image intensity but also degree of coherence for image. Simulation results of the degree of coherence for image given by the coherency matrix in imaging system correspond to the complex degree of coherence obtained by the van Cittert-Zernike theorem.

  5. Coherent hybrid electromagnetic field imaging

    Science.gov (United States)

    Cooke, Bradly J.; Guenther, David C.

    2008-08-26

    An apparatus and corresponding method for coherent hybrid electromagnetic field imaging of a target, where an energy source is used to generate a propagating electromagnetic beam, an electromagnetic beam splitting means to split the beam into two or more coherently matched beams of about equal amplitude, and where the spatial and temporal self-coherence between each two or more coherently matched beams is preserved. Two or more differential modulation means are employed to modulate each two or more coherently matched beams with a time-varying polarization, frequency, phase, and amplitude signal. An electromagnetic beam combining means is used to coherently combine said two or more coherently matched beams into a coherent electromagnetic beam. One or more electromagnetic beam controlling means are used for collimating, guiding, or focusing the coherent electromagnetic beam. One or more apertures are used for transmitting and receiving the coherent electromagnetic beam to and from the target. A receiver is used that is capable of square-law detection of the coherent electromagnetic beam. A waveform generator is used that is capable of generation and control of time-varying polarization, frequency, phase, or amplitude modulation waveforms and sequences. A means of synchronizing time varying waveform is used between the energy source and the receiver. Finally, a means of displaying the images created by the interaction of the coherent electromagnetic beam with target is employed.

  6. SAR image effects on coherence and coherence estimation.

    Energy Technology Data Exchange (ETDEWEB)

    Bickel, Douglas Lloyd

    2014-01-01

    Radar coherence is an important concept for imaging radar systems such as synthetic aperture radar (SAR). This document quantifies some of the effects in SAR which modify the coherence. Although these effects can disrupt the coherence within a single SAR image, this report will focus on the coherence between separate images, such as for coherent change detection (CCD) processing. There have been other presentations on aspects of this material in the past. The intent of this report is to bring various issues that affect the coherence together in a single report to support radar engineers in making decisions about these matters.

  7. Image Enhancement By Partially Coherent Imaging

    Science.gov (United States)

    Rhodes, William T.; Koizumi, M.

    1983-04-01

    A partially coherent Koehler-illumination imaging system equipped with complementary masks in source and pupil planes can be used to perform image enhancement operations such as directional or non-directional edge enhancement and emphasis of spatial bandpass features. With many objects the use of complementary masks results in high-contrast images. Underlying principles are explained and preliminary experimental results presented.

  8. Birefringent coherent diffraction imaging

    Science.gov (United States)

    Karpov, Dmitry; dos Santos Rolo, Tomy; Rich, Hannah; Kryuchkov, Yuriy; Kiefer, Boris; Fohtung, E.

    2016-10-01

    Directional dependence of the index of refraction contains a wealth of information about anisotropic optical properties in semiconducting and insulating materials. Here we present a novel high-resolution lens-less technique that uses birefringence as a contrast mechanism to map the index of refraction and dielectric permittivity in optically anisotropic materials. We applied this approach successfully to a liquid crystal polymer film using polarized light from helium neon laser. This approach is scalable to imaging with diffraction-limited resolution, a prospect rapidly becoming a reality in view of emergent brilliant X-ray sources. Applications of this novel imaging technique are in disruptive technologies, including novel electronic devices, in which both charge and spin carry information as in multiferroic materials and photonic materials such as light modulators and optical storage.

  9. Imaging granulomatous lesions with optical coherence tomography

    DEFF Research Database (Denmark)

    Banzhaf, Christina; Jemec, Gregor B E

    2012-01-01

    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....

  10. Application of coherent 10 micron imaging lidar

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, M.L.; Hutchinson, D.P.; Richards, R.K.; Bennett, C.A.

    1997-04-01

    With the continuing progress in mid-IR array detector technology and high bandwidth fan-outs, i.f. electronics, high speed digitizers, and processing capability, true coherent imaging lidar is becoming a reality. In this paper experimental results are described using a 10 micron coherent imaging lidar.

  11. Retinal Optical Coherence Tomography Imaging

    Science.gov (United States)

    Drexler, Wolfgang; Fujimoto, James G.

    The eye is essentially transparent, transmitting light with only minimal optical attenuation and scattering providing easy optical access to the anterior segment as well as the retina. For this reason, ophthalmic and especially retinal imaging has been not only the first but also most successful clinical application for optical coherence tomography (OCT). This chapter focuses on the development of OCT technology for retinal imaging. OCT has significantly improved the potential for early diagnosis, understanding of retinal disease pathogenesis, as well as monitoring disease progression and response to therapy. Development of ultrabroad bandwidth light sources and high-speed detection techniques has enabled significant improvements in ophthalmic OCT imaging performance, demonstrating the potential of three-dimensional, ultrahigh-resolution OCT (UHR OCT) to perform noninvasive optical biopsy of the living human retina, i.e., the in vivo visualization of microstructural, intraretinal morphology in situ approaching the resolution of conventional histopathology. Significant improvements in axial resolution and speed not only enable three-dimensional rendering of retinal volumes but also high-definition, two-dimensional tomograms, topographic thickness maps of all major intraretinal layers, as well as volumetric quantification of pathologic intraretinal changes. These advances in OCT technology have also been successfully applied in several animal models of retinal pathologies. The development of light sources emitting at alternative wavelengths, e.g., around #1,060 nm, not only enabled three-dimensional OCT imaging with enhanced choroidal visualization but also improved OCT performance in cataract patients due to reduced scattering losses in this wavelength region. Adaptive optics using deformable mirror technology, with unique high stroke to correct higher-order ocular aberrations, with specially designed optics to compensate chromatic aberration of the human eye, in

  12. Coherence measurements and coherent diffractive imaging at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Vartanyants, I A; Mancuso, A P; Singer, A; Yefanov, O M; Gulden, J, E-mail: ivan.vartaniants@desy.d [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg (Germany)

    2010-10-14

    We present an overview of recent experiments performed at the free-electron laser (FEL) FLASH at DESY in Hamburg. Experiments were focused on coherence measurements and coherent x-ray diffractive imaging (CXDI) of periodic and non-periodic biological samples. Young's double slit experiment was performed at FLASH to measure its coherence properties at a fundamental wavelength of 13.7 nm. Additionally, a uniformly redundant array was used to measure the coherence properties of the third harmonic (2.7 nm) of an 8 nm fundamental wavelength at FLASH. Coherent imaging of a two-dimensional (2D) finite crystal structure using a single pulse train of FLASH radiation was demonstrated. We show that the structure is reconstructed to the detector-limited resolution of 220 nm, given an adequate signal to noise ratio. We have also employed CXDI in a non-destructive regime to compare the images of a biological sample using single, femtosecond pulses of FLASH radiation. We have verified that images reconstructed using CXDI are similar for statistically different FEL pulses. We have also demonstrated Fourier transform holography of the same biological sample and present diffraction data measured at the third harmonic of FLASH, reaching into the water window.

  13. Phase retrieval by coherent modulation imaging

    Science.gov (United States)

    Zhang, Fucai; Chen, Bo; Morrison, Graeme R.; Vila-Comamala, Joan; Guizar-Sicairos, Manuel; Robinson, Ian K.

    2016-11-01

    Phase retrieval is a long-standing problem in imaging when only the intensity of the wavefield can be recorded. Coherent diffraction imaging is a lensless technique that uses iterative algorithms to recover amplitude and phase contrast images from diffraction intensity data. For general samples, phase retrieval from a single-diffraction pattern has been an algorithmic and experimental challenge. Here we report a method of phase retrieval that uses a known modulation of the sample exit wave. This coherent modulation imaging method removes inherent ambiguities of coherent diffraction imaging and uses a reliable, rapidly converging iterative algorithm involving three planes. It works for extended samples, does not require tight support for convergence and relaxes dynamic range requirements on the detector. Coherent modulation imaging provides a robust method for imaging in materials and biological science, while its single-shot capability will benefit the investigation of dynamical processes with pulsed sources, such as X-ray free-electron lasers.

  14. Phase retrieval by coherent modulation imaging

    Science.gov (United States)

    Zhang, Fucai; Chen, Bo; Morrison, Graeme R.; Vila-Comamala, Joan; Guizar-Sicairos, Manuel; Robinson, Ian K.

    2016-01-01

    Phase retrieval is a long-standing problem in imaging when only the intensity of the wavefield can be recorded. Coherent diffraction imaging is a lensless technique that uses iterative algorithms to recover amplitude and phase contrast images from diffraction intensity data. For general samples, phase retrieval from a single-diffraction pattern has been an algorithmic and experimental challenge. Here we report a method of phase retrieval that uses a known modulation of the sample exit wave. This coherent modulation imaging method removes inherent ambiguities of coherent diffraction imaging and uses a reliable, rapidly converging iterative algorithm involving three planes. It works for extended samples, does not require tight support for convergence and relaxes dynamic range requirements on the detector. Coherent modulation imaging provides a robust method for imaging in materials and biological science, while its single-shot capability will benefit the investigation of dynamical processes with pulsed sources, such as X-ray free-electron lasers. PMID:27857061

  15. Coherent photoacoustic-ultrasound correlation and imaging.

    Science.gov (United States)

    Gao, Fei; Feng, Xiaohua; Zheng, Yuanjin

    2014-09-01

    Both photoacoustics and ultrasound have been researched extensively but separately. In this letter, we report an initial study on the coherent correlation between pulsed photoacoustic wave and pulse-echo ultrasound wave. By illuminating an object with a pulsed laser and external ultrasound sequentially, both the endogenous photoacoustic wave and pulse-echo ultrasound wave are received and coherently correlated, demonstrating enhanced signal-to-noise ratio. Image contrast of the proposed coherent photoacoustic-ultrasound imaging is also demonstrated to be improved significantly on vessel-mimicking phantom, due to fusion of the optical absorption and ultrasound reflection contrasts by coherent correlation of either conventional laser-induced photoacoustic imaging or pulse-echo ultrasound imaging separately.

  16. Harmonic Spatial Coherence Imaging: An Ultrasonic Imaging Method Based on Backscatter Coherence

    OpenAIRE

    DAHL, JEREMY J.; Jakovljevic, Marko; Pinton, Gianmarco F.; Trahey, Gregg E.

    2012-01-01

    HSCI and SLSC imaging less sensitive to clutter because it has low spatial coherence. The method is based on the coherence of the second harmonic backscatter. Because the same signals that are used to construct harmonic B-mode images are also used to construct HSCI images, the benefits obtained with harmonic imaging are also applicable to HSCI. Harmonic imaging has been the primary tool for suppressing clutter in diagnostic ultrasound imaging, however second harmonic echoes are not necessaril...

  17. Coherent infrared imaging camera (CIRIC)

    Energy Technology Data Exchange (ETDEWEB)

    Hutchinson, D.P.; Simpson, M.L.; Bennett, C.A.; Richards, R.K.; Emery, M.S.; Crutcher, R.I.; Sitter, D.N. Jr.; Wachter, E.A.; Huston, M.A.

    1995-07-01

    New developments in 2-D, wide-bandwidth HgCdTe (MCT) and GaAs quantum-well infrared photodetectors (QWIP) coupled with Monolithic Microwave Integrated Circuit (MMIC) technology are now making focal plane array coherent infrared (IR) cameras viable. Unlike conventional IR cameras which provide only thermal data about a scene or target, a coherent camera based on optical heterodyne interferometry will also provide spectral and range information. Each pixel of the camera, consisting of a single photo-sensitive heterodyne mixer followed by an intermediate frequency amplifier and illuminated by a separate local oscillator beam, constitutes a complete optical heterodyne receiver. Applications of coherent IR cameras are numerous and include target surveillance, range detection, chemical plume evolution, monitoring stack plume emissions, and wind shear detection.

  18. Coherent Scattering Imaging Monte Carlo Simulation

    Science.gov (United States)

    Hassan, Laila Abdulgalil Rafik

    Conventional mammography has poor contrast between healthy and cancerous tissues due to the small difference in attenuation properties. Coherent scatter potentially provides more information because interference of coherently scattered radiation depends on the average intermolecular spacing, and can be used to characterize tissue types. However, typical coherent scatter analysis techniques are not compatible with rapid low dose screening techniques. Coherent scatter slot scan imaging is a novel imaging technique which provides new information with higher contrast. In this work a simulation of coherent scatter was performed for slot scan imaging to assess its performance and provide system optimization. In coherent scatter imaging, the coherent scatter is exploited using a conventional slot scan mammography system with anti-scatter grids tilted at the characteristic angle of cancerous tissues. A Monte Carlo simulation was used to simulate the coherent scatter imaging. System optimization was performed across several parameters, including source voltage, tilt angle, grid distances, grid ratio, and shielding geometry. The contrast increased as the grid tilt angle increased beyond the characteristic angle for the modeled carcinoma. A grid tilt angle of 16 degrees yielded the highest contrast and signal to noise ratio (SNR). Also, contrast increased as the source voltage increased. Increasing grid ratio improved contrast at the expense of decreasing SNR. A grid ratio of 10:1 was sufficient to give a good contrast without reducing the intensity to a noise level. The optimal source to sample distance was determined to be such that the source should be located at the focal distance of the grid. A carcinoma lump of 0.5x0.5x0.5 cm3 in size was detectable which is reasonable considering the high noise due to the usage of relatively small number of incident photons for computational reasons. A further study is needed to study the effect of breast density and breast thickness

  19. Spaceborne SAR Imaging Algorithm for Coherence Optimized.

    Directory of Open Access Journals (Sweden)

    Zhiwei Qiu

    Full Text Available This paper proposes SAR imaging algorithm with largest coherence based on the existing SAR imaging algorithm. The basic idea of SAR imaging algorithm in imaging processing is that output signal can have maximum signal-to-noise ratio (SNR by using the optimal imaging parameters. Traditional imaging algorithm can acquire the best focusing effect, but would bring the decoherence phenomenon in subsequent interference process. Algorithm proposed in this paper is that SAR echo adopts consistent imaging parameters in focusing processing. Although the SNR of the output signal is reduced slightly, their coherence is ensured greatly, and finally the interferogram with high quality is obtained. In this paper, two scenes of Envisat ASAR data in Zhangbei are employed to conduct experiment for this algorithm. Compared with the interferogram from the traditional algorithm, the results show that this algorithm is more suitable for SAR interferometry (InSAR research and application.

  20. When holography meets coherent diffraction imaging

    CERN Document Server

    Latychevskaia, Tatiana; Fink, Hans-Werner

    2011-01-01

    In understanding the physical, chemical and biological properties of a molecule by obtaining detailed information about its structure, there is an ultimate wish: the visualization of this very molecule in three dimensions at atomic scale, rather than obtaining structural information by averaging over an ensemble of molecules. Coherent diffraction imaging (CDI) is a modern lens-less imaging technique promising exactly that: visualizing an individual molecule at the highest possible resolution solely limited by the radiation wavelength. Individual bacteria and viruses have been imaged by CDI employing coherent X-rays and recently, CDI has been extended to recover the three-dimensional shape of objects from a single diffraction pattern. Higher resolution is expected with the implementation of bright coherent radiation from X-ray free electron lasers. Since detectors are only sensitive to intensity, the phase of the wave is missing and must somehow be recovered to reconstruct the molecule's anatomy. There are two...

  1. Harmonic spatial coherence imaging: an ultrasonic imaging method based on backscatter coherence.

    Science.gov (United States)

    Dahl, Jeremy; Jakovljevic, Marko; Pinton, Gianmarco F; Trahey, Gregg E

    2012-04-01

    We introduce a harmonic version of the short-lag spatial coherence (SLSC) imaging technique, called harmonic spatial coherence imaging (HSCI). The method is based on the coherence of the second-harmonic backscatter. Because the same signals that are used to construct harmonic B-mode images are also used to construct HSCI images, the benefits obtained with harmonic imaging are also obtained with HSCI. Harmonic imaging has been the primary tool for suppressing clutter in diagnostic ultrasound imaging, however secondharmonic echoes are not necessarily immune to the effects of clutter. HSCI and SLSC imaging are less sensitive to clutter because clutter has low spatial coherence. HSCI shows favorable imaging characteristics such as improved contrast-to-noise ratio (CNR), improved speckle SNR, and better delineation of borders and other structures compared with fundamental and harmonic B-mode imaging. CNRs of up to 1.9 were obtained from in vivo imaging of human cardiac tissue with HSCI, compared with 0.6, 0.9, and 1.5 in fundamental B-mode, harmonic B-mode, and SLSC imaging, respectively. In vivo experiments in human liver tissue demonstrated SNRs of up to 3.4 for HSCI compared with 1.9 for harmonic B-mode. Nonlinear simulations of a heart chamber model were consistent with the in vivo experiments.

  2. A Semantic Connected Coherence Scheme for Efficient Image Segmentation

    Directory of Open Access Journals (Sweden)

    S.Pannirselvam

    2012-06-01

    Full Text Available Image processing is a comprehensively research topic with an elongated history. Segmenting an image is the most challenging and difficult task in image processing and analysis. The principal intricacy met in image segmentation is the ability of techniques to discover semantic objects efficiently from an image without any prior knowledge. One recent work presented connected coherence tree algorithm (CCTA for image segmentation (with no prior knowledge which discovered regions of semantic coherence based on neighbor coherence segmentation criteria. It deployed an adaptive spatial scale and a suitable intensity-difference scale to extract several sets of coherent neighboring pixels and maximize the probability of single image content and minimize complex backgrounds. However CCTA segmented images either consists of small, lengthy and slender objects or rigorously ruined by noise, irregular lighting, occlusion, poor illumination, and shadow.In this paper, we present a Cluster based Semantic Coherent Tree (CBSCT scheme for image segmentation. CBSCT’s initial work is on the semantic connected coherence criteria for the image segregation. Semantic coherent regions are clustered based on Bayesian nearest neighbor search of neighborhood pixels. The segmentation regions are extracted from the images based on the cluster object purity obtained through semantic coherent regions. The clustered image regions are post processed with non linear noise filters. Performance metrics used in the evaluation of CBSCT are semantic coherent pixel size, number of cluster objects, and purity levels of the cluster, segmented coherent region intensity threshold, and quality of segmented images in terms of image clarity with PSNR.

  3. Enhanced high-speed coherent diffraction imaging

    Science.gov (United States)

    Potier, Jonathan; Fricker, Sebastien; Idir, Mourad

    2011-03-01

    Due to recent advances in X-ray microscopy, we are now able to image objects with nanometer resolution thanks to Synchrotron beam lines or Free Electron Lasers (FEL). The PCI (Phase Contrast Imaging) is a robust technique that can recover the wavefront from measurements of only few intensity pictures in the Fresnel diffraction region. With our fast straightforward calculus methods, we manage to provide the phase induced by a microscopic specimen in few seconds. We can therefore obtain high contrasted images from transparent materials at very small scales. To reach atomic resolution imaging and thus make a transition from the near to the far field, the Coherent Diffraction Imaging (CDI) technique finds its roots in the analysis of diffraction patterns to obtain the phase of the altered complex wave. Theoretical results about existence and uniqueness of this retrieved piece of information by both iterative and direct algorithms have already been released. However, performances of algorithms remain limited by the coherence of the X-ray beam, presence of random noise and the saturation threshold of the detector. We will present reconstructions of samples using an enhanced version of HIO algorithm improving the speed of convergence and its repeatability. As a first step toward a practical X-Ray CDI system, initial images for reconstructions are acquired with the laser-based CDI system working in the visible spectrum.

  4. ISAR Echoes Coherent Processing and Imaging

    Institute of Scientific and Technical Information of China (English)

    XINGMengdao; LANJinqiao; BAOZheng; LIAOGuisheng

    2004-01-01

    The general approach to ISAR imaging is Range-doppler (RD) imaging approach. For this approach,the Translational motion compensation (TMC) is firstly obtained by envelope alignment and autofocus, so the target can be treated as a rotating target for the next processing. But in this method, scatterers' Migration through resolution cells (MTRC) caused by rotational motion is neglected. However in practice, MTRC exists with the improvement of resolution or for big target. For MTRC compensation, the keystone transformation in SAR is used inthis paper. Before the keystone transformation, it is demanded that the rawdata is coherent, while in fact, the ISAR rawdata is usually not. So a coherent processing of rawdata is proposed. In this paper, the coherent processing of rawdata is firstly done and the next step is to correct MTRC. After using multi-component Amplitude modulation and Linear frequency modulation (AM-LFM) parameter estimation method, the Range-Instantaneous Doppler(RID) ISAR image is obtained. The effectiveness of this algorithm is validated by the processing of simulation data.

  5. Impact of wave front and coherence optimization in coherent diffractive imaging.

    Science.gov (United States)

    Ge, X; Boutu, W; Gauthier, D; Wang, F; Borta, A; Barbrel, B; Ducousso, M; Gonzalez, A I; Carré, B; Guillaumet, D; Perdrix, M; Gobert, O; Gautier, J; Lambert, G; Maia, F R N C; Hajdu, J; Zeitoun, P; Merdji, H

    2013-05-01

    We present single shot nanoscale imaging using a table-top femtosecond soft X-ray laser harmonic source at a wavelength of 32 nm. We show that the phase retrieval process in coherent diffractive imaging critically depends on beam quality. Coherence and image fidelity are measured from single-shot coherent diffraction patterns of isolated nano-patterned slits. Impact of flux, wave front and coherence of the soft X-ray beam on the phase retrieval process and the image quality are discussed. After beam improvements, a final image reconstruction is presented with a spatial resolution of 78 nm (half period) in a single 20 fs laser harmonic shot.

  6. Image Distortion of Optical Coherence Tomography

    Institute of Scientific and Technical Information of China (English)

    安源; 姚建铨

    2004-01-01

    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.

  7. Coherently dedispersed gated imaging of millisecond pulsars

    CERN Document Server

    Roy, Jayanta

    2013-01-01

    Motivated by the need for rapid localisation of newly discovered faint millisecond pulsars (MSPs) we have developed a coherently dedispersed gating correlator. This gating correlator accounts for the orbital motions of MSPs in binaries while folding the visibilities with best-fit topocentric rotational model derived from periodicity search in simultaneously generated beamformer output. Unique applications of the gating correlator for sensitive interferometric studies of MSPs are illustrated using the Giant Metrewave Radio Telescope (GMRT) interferometric array. We could unambiguously localise five newly discovered Fermi MSPs in the on-off gated image plane with an accuracy of +-1". Immediate knowledge of such precise position allows the use of sensitive coherent beams of array telescopes for follow-up timing observations, which substantially reduces the use of telescope time (~ 20X for the GMRT). In addition, precise a-priori astrometric position reduces the effect of large covariances in timing fit (with dis...

  8. Optical coherence tomography for endodontic imaging

    Science.gov (United States)

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

    2008-02-01

    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.

  9. Imaging Granulomatous Lesions with Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Christina Banzhaf

    2012-01-01

    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.

  10. Coherent Diffractive Imaging Using Randomly Coded Masks

    CERN Document Server

    Seaberg, Matthew H; Turner, Joshua J

    2015-01-01

    Coherent diffractive imaging (CDI) provides new opportunities for high resolution X-ray imaging with simultaneous amplitude and phase contrast. Extensions to CDI broaden the scope of the technique for use in a wide variety of experimental geometries and physical systems. Here, we experimentally demonstrate a new extension to CDI that encodes additional information through the use of a series of randomly coded masks. The information gained from the few additional diffraction measurements removes the need for typical object-domain constraints; the algorithm uses prior information about the masks instead. The experiment is performed using a laser diode at 532.2 nm, enabling rapid prototyping for future X-ray synchrotron and even free electron laser experiments. Diffraction patterns are collected with up to 15 different masks placed between a CCD detector and a single sample. Phase retrieval is performed using a convex relaxation routine known as "PhaseCut" followed by a variation on Fienup's input-output algorit...

  11. Coherent diffractive imaging using randomly coded masks

    Energy Technology Data Exchange (ETDEWEB)

    Seaberg, Matthew H., E-mail: seaberg@slac.stanford.edu [CNRS and D.I., UMR 8548, École Normale Supérieure, 45 Rue d' Ulm, 75005 Paris (France); Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); D' Aspremont, Alexandre [CNRS and D.I., UMR 8548, École Normale Supérieure, 45 Rue d' Ulm, 75005 Paris (France); Turner, Joshua J. [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States)

    2015-12-07

    We experimentally demonstrate an extension to coherent diffractive imaging that encodes additional information through the use of a series of randomly coded masks, removing the need for typical object-domain constraints while guaranteeing a unique solution to the phase retrieval problem. Phase retrieval is performed using a numerical convex relaxation routine known as “PhaseCut,” an iterative algorithm known for its stability and for its ability to find the global solution, which can be found efficiently and which is robust to noise. The experiment is performed using a laser diode at 532.2 nm, enabling rapid prototyping for future X-ray synchrotron and even free electron laser experiments.

  12. Anterior Eye Imaging with Optical Coherence Tomography

    Science.gov (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.

  13. Phase space representation of spatially partially coherent imaging.

    Science.gov (United States)

    Castaneda, Roman

    2008-08-01

    The phase space representation of imaging with optical fields in any state of spatial coherence is developed by using spatial coherence wavelets. It leads to new functions for describing the optical transfer and response of imaging systems when the field is represented by Wigner distribution functions. Specific imaging cases are analyzed in this context, and special attention is devoted to the imaging of two point sources.

  14. Coherent imaging with incoherent light in digital holographic microscopy

    Science.gov (United States)

    Chmelik, Radim

    2012-01-01

    Digital holographic microscope (DHM) allows for imaging with a quantitative phase contrast. In this way it becomes an important instrument, a completely non-invasive tool for a contrast intravital observation of living cells and a cell drymass density distribution measurement. A serious drawback of current DHMs is highly coherent illumination which makes the lateral resolution worse and impairs the image quality by a coherence noise and a parasitic interference. An uncompromising solution to this problem can be found in the Leith concept of incoherent holography. An off-axis hologram can be formed with arbitrary degree of light coherence in systems equipped with an achromatic interferometer and thus the resolution and the image quality typical for an incoherent-light wide-field microscopy can be achieved. In addition, advanced imaging modes based on limited coherence can be utilized. The typical example is a coherence-gating effect which provides a finite axial resolution and makes DHM image similar to that of a confocal microscope. These possibilities were described theoretically using the formalism of three-dimensional coherent transfer functions and proved experimentally by the coherence-controlled holographic microscope which is DHM based on the Leith achromatic interferometer. Quantitative-phase-contrast imaging is demonstrated with incoherent light by the living cancer cells observation and their motility evaluation. The coherence-gating effect was proved by imaging of model samples through a scattering layer and living cells inside an opalescent medium.

  15. The Coherent X-ray Imaging instrument at the Linac Coherent Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Mengning; Williams, Garth J.; Messerschmidt, Marc; Seibert, M. Marvin; Montanez, Paul A.; Hayes, Matt; Milathianaki, Despina; Aquila, Andrew; Hunter, Mark S.; Koglin, Jason E.; Schafer, Donald W.; Guillet, Serge; Busse, Armin; Bergan, Robert; Olson, William; Fox, Kay; Stewart, Nathaniel; Curtis, Robin; Miahnahri, Alireza Alan; Boutet, Sébastien, E-mail: sboutet@slac.stanford.edu [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

    2015-04-15

    Description of the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source. Recent scientific highlights illustrate the femtosecond crystallography, high power density and extreme matter capabilities of the CXI instrument. The Coherent X-ray Imaging (CXI) instrument specializes in hard X-ray, in-vacuum, high power density experiments in all areas of science. Two main sample chambers, one containing a 100 nm focus and one a 1 µm focus, are available, each with multiple diagnostics, sample injection, pump–probe and detector capabilities. The flexibility of CXI has enabled it to host a diverse range of experiments, from biological to extreme matter.

  16. Coherent imaging with pseudo-thermal incoherent light

    DEFF Research Database (Denmark)

    Gatti, A.; Bache, Morten; Magatti, D.

    2006-01-01

    We investigate experimentally fundamental properties of coherent ghost imaging using spatially incoherent beams generated from a pseudo-thermal source. A complementarity between the coher- ence of the beams and the correlation between them is demonstrated by showing a complementarity between ghos...

  17. The effects of spatiotemporal coherence on interferometric imaging

    CERN Document Server

    Shin, Seungwoo; Lee, KyeoReh; Lee, SangYun; Park, YongKeun

    2016-01-01

    Illumination coherence plays a major role in various imaging systems, from microscopy, metrology, digital holography, optical coherence tomography, to ultrasound imaging. Here, we present a systematic study on the effects of degrees of spatiotemporal coherence of an illumination (DSTCI) on imaging quality. An optical field with arbitrary DSTCI was decomposed into wavelets with constituent spatiotemporal frequencies, and the effects on image quality were quantitatively investigated. The results show the synergistic effects on reduction of speckle noise when DSTCI is decreased. This study presents a method to systematically control DSTCI, and the result provides an essential reference on the effects of DSTCI on imaging quality. We believe that the presented methods and results can be implemented in various imaging systems for characterising and improving imaging quality.

  18. Phase-sensitive fluorescent imaging with coherent reconstruction

    CERN Document Server

    Field, Jeffrey J; Bartels, Randy A

    2015-01-01

    Optical imaging plays a critical role in advancing our understanding of three dimensional dynamics of biological systems. Coherent imaging (CI) methods exploit spatial phase information, encoded through propagation of coherent signal light emerging from a specimen, to extract a three-dimensional representation of the object from a single high-speed measurement. Until now, CI methods could not be applied to incoherent light, severely limiting their ability to image the most powerful biological probes available - fluorescent molecules - with sufficient speed and volume to observe important processes, such as neural processing in live specimens. We introduce a new imaging technique that transfers the spatial propagation phase of coherent illumination light to incoherent fluorescent light emission. The transfer of propagation phase allows CI techniques to be applied to fluorescent light imaging, and leads to large increases in imaging speed and depth of field. With this advance, biological imaging of fluorescent ...

  19. Coherence and aberration effects in surface plasmon polariton imaging

    OpenAIRE

    Berthel, Martin; Jiang, Quanbo; Chartrand, Camille; Bellessa, Joel; Huant, Serge; Genet, Cyriaque; Drezet, Aurélien

    2016-01-01

    We study theoretically and experimentally coherent imaging of surface plasmon polaritons using either leakage radiation microscopy through a thin metal film or interference microscopy through a thick metal film. Using a rigorous modal formalism based on scalar Whittaker potentials we develop a systematic analytical and vectorial method adapted to the analysis of coherent imaging involving surface plasmon polaritons. The study includes geometrical aberrations due index mismatch which played an...

  20. Coherence switching of a degenerate VECSEL for multimodality imaging

    CERN Document Server

    Knitter, Sebastian; Redding, Brandon; Khokha, Mustafa K; Choma, Michael A; Cao, Hui

    2015-01-01

    We demonstrate a VECSEL (vertical external cavity surface emitting laser) based degenerate source with an adjustable degree of spatial coherence that is electrically pumped, mechanically compact and supports continuous-wave emission. The laser operation can be switched between a large number of mutually incoherent spatial modes and few-mode operation at little power loss. This technology allows multimodality imaging, where low spatial coherence illumination is used for traditional high-speed video-microscopy and high spatial coherence illumination is used to extract dynamic information of flow processes. The initial demonstration is performed on imaging embryo heart function in Xenopus, which is an important animal model for human heart disease.

  1. Integrated optical coherence tomography and optical coherence microscopy imaging of human pathology

    Science.gov (United States)

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

    2010-02-01

    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.

  2. Water Window Ptychographic Imaging with Characterized Coherent X-rays

    CERN Document Server

    Rose, Max; Dzhigaev, Dmitry; Gorobtsov, Oleg; Senkbeil, Tobias; von Gundlach, Andreas; Gorniak, Thomas; Shabalin, Anatoly; Viefhaus, Jens; Rosenhahn, Axel; Vartanyants, Ivan

    2015-01-01

    We report on a ptychographical coherent diffractive imaging experiment in the water window with focused soft X-rays at $500~\\mathrm{eV}$. An X-ray beam with high degree of coherence was selected for ptychography at the P04 beamline of the PETRA III synchrotron radiation source. We measured the beam coherence with the newly developed non-redundant array method. A pinhole $2.6~\\mathrm{\\mu m}$ in size selected the coherent part of the beam and was used for ptychographic measurements of a lithographically manufactured test sample and fossil diatom. The achieved resolution was $53~\\mathrm{nm}$ for the test sample and only limited by the size of the detector. The diatom was imaged at a resolution better than $90~\\mathrm{nm}$.

  3. Coherent processing for ISAR imaging with sparse apertures

    Institute of Scientific and Technical Information of China (English)

    SHENG JiaLian; ZHANG Lei; XU Gang; XING MengDao; BAO Zheng

    2012-01-01

    To implement target detection,tracking and imaging in a multifunctional radar system,the wideband measurements for inverse synthetic aperture radar (ISAR) imaging are usually sparsely recorded.Considering the incoherence problem in such sparse-aperture ISAR (SA-ISAR) systems,we concentrate on the study of a coherent processing method in this work.Based on an all-pole model,the incoherence parameters between abutting sub-apertures can be effectively estimated.After coherence compensation,an optimization-based SA-ISAR imaging approach is provided from the view of statistics.Simulation and real data experiments validate the feasibility and effectiveness of the proposals.

  4. Coherent fiber supercontinuum laser for nonlinear biomedical imaging

    Science.gov (United States)

    Tu, Haohua; Liu, Yuan; Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry; Boppart, Stephen A.

    2012-12-01

    Nonlinear biomedical imaging has not benefited from the well-known techniques of fiber supercontinuum generation for reasons such as poor coherence (or high noise), insufficient controllability, low spectral power intensity, and inadequate portability. Fortunately, a few techniques involving nonlinear fiber optics and femtosecond fiber laser development have emerged to overcome these critical limitations. These techniques pave the way for conducting point-of-care nonlinear biomedical imaging by a low-maintenance cost-effective coherent fiber supercontinuum laser, which covers a broad emission wavelength of 350-1700 nm. A prototype of this laser has been demonstrated in label-free multimodal nonlinear imaging of cell and tissue samples.

  5. Coherence and aberration effects in surface plasmon polariton imaging

    CERN Document Server

    Berthel, Martin; Chartrand, Camille; Bellessa, Joel; Huant, Serge; Genet, Cyriaque; Drezet, Aurélien

    2016-01-01

    We study theoretically and experimentally coherent imaging of surface plasmon polaritons using either leakage radiation microscopy through a thin metal film or interference microscopy through a thick metal film. Using a rigorous modal formalism based on scalar Whittaker potentials we develop a systematic analytical and vectorial method adapted to the analysis of coherent imaging involving surface plasmon polaritons. The study includes geometrical aberrations due index mismatch which played an important role in the interpretation of recent experiments using leakage radiation microscopy. We compare our theory with experiments using classical or quantum near-field scanning optical microscopy probes and show that the approach leads to a full interpretation of the recorded optical images.

  6. Coherence and aberration effects in surface plasmon polariton imaging

    Science.gov (United States)

    Berthel, Martin; Jiang, Quanbo; Chartrand, Camille; Bellessa, Joel; Huant, Serge; Genet, Cyriaque; Drezet, Aurélien

    2015-09-01

    We study theoretically and experimentally coherent imaging of surface plasmon polaritons using either leakage radiation microscopy through a thin metal film or interference microscopy through a thick metal film. Using a rigorous modal formalism based on scalar Whittaker potentials, we develop a systematic analytical and vectorial method adapted to the analysis of coherent imaging involving surface plasmon polaritons. The study includes geometrical aberrations due index mismatch which played an important role in the interpretation of recent experiments using leakage radiation microscopy. We compare our theory with experiments using classical or quantum near-field scanning optical microscopy probes and show that the approach leads to a full interpretation of the recorded optical images.

  7. Ex vivo imaging of human thyroid pathology using integrated optical coherence tomography and optical coherence microscopy

    Science.gov (United States)

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

    2010-01-01

    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 sections. Characteristic features that suggest malignant lesions, such as complex papillary architecture, microfollicules, psammomatous calcifications, or replacement of normal follicular architecture with sheets/nests of 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.

  8. Heisenberg scaling of imaging resolution by coherent enhancement

    CERN Document Server

    McConnell, Robert; Yoder, Theodore J; Bruzewicz, Colin D; Chuang, Isaac L; Chiaverini, John; Sage, Jeremy M

    2016-01-01

    Classical imaging works by scattering photons from an object to be imaged, and achieves resolution scaling as $1/\\sqrt{t}$, with $t$ the imaging time. By contrast, the laws of quantum mechanics allow one to utilize quantum coherence to obtain imaging resolution that can scale as quickly as $1/t$ -- the so-called "Heisenberg limit." However, ambiguities in the obtained signal often preclude taking full advantage of this quantum enhancement, while imaging techniques designed to be unambiguous often lose this optimal Heisenberg scaling. Here, we demonstrate an imaging technique which combines unambiguous detection of the target with Heisenberg scaling of the resolution. We also demonstrate a binary search algorithm which can efficiently locate a coherent target using the technique, resolving a target trapped ion to within 3% of the $1/e^2$ diameter of the excitation beam.

  9. Coherent temporal imaging with analog time-bandwidth compression

    CERN Document Server

    Asghari, Mohammad H

    2013-01-01

    We introduce the concept of coherent temporal imaging and its combination with the anamorphic stretch transform. The new system can measure both temporal profile of fast waveforms as well as their spectrum in real time and at high-throughput. We show that the combination of coherent detection and warped time-frequency mapping also performs time-bandwidth compression. By reducing the temporal width without sacrificing spectral resolution, it addresses the Big Data problem in real time instruments. The proposed method is the first application of the recently demonstrated Anamorphic Stretch Transform to temporal imaging. Using this method narrow spectral features beyond the spectrometer resolution can be captured. At the same time the output bandwidth and hence the record length is minimized. Coherent detection allows the temporal imaging and dispersive Fourier transform systems to operate in the traditional far field as well as in near field regimes.

  10. Biological imaging with coherent Raman scattering microscopy: a tutorial

    Science.gov (United States)

    Alfonso-García, Alba; Mittal, Richa; Lee, Eun Seong; Potma, Eric O.

    2014-01-01

    Abstract. Coherent Raman scattering (CRS) microscopy is gaining acceptance as a valuable addition to the imaging toolset of biological researchers. Optimal use of this label-free imaging technique benefits from a basic understanding of the physical principles and technical merits of the CRS microscope. This tutorial offers qualitative explanations of the principles behind CRS microscopy and provides information about the applicability of this nonlinear optical imaging approach for biological research. PMID:24615671

  11. En-face coherence imaging using galvanometer scanner modulation.

    Science.gov (United States)

    Podoleanu, A G; Dobre, G M; Jackson, D A

    1998-02-01

    We introduce a novel optical path-modulation technique for a low-coherence interferometric imaging system based on transverse scanning of the target with a galvanometric scanning-mirror pair. The path modulation arises when the beam that is incident upon one of the scanning mirrors does not fall on its axis of rotation. The method is demonstrated by the production of en-face low-coherence images of different objects such as a fiber-optic tip and a human retina invivo .

  12. Synchronous imaging of coherent plasma fluctuations

    Science.gov (United States)

    Haskey, S. R.; Thapar, N.; Blackwell, B. D.; Howard, J.

    2014-03-01

    A new method for imaging high frequency plasma fluctuations is described. A phase locked loop and field programmable gate array are used to generate gating triggers for an intensified CCD camera. A reference signal from another diagnostic such as a magnetic probe ensures that the triggers are synchronous with the fluctuation being imaged. The synchronous imaging technique allows effective frame rates exceeding millions per second, good signal to noise through the accumulation of multiple exposures per frame, and produces high resolution images without generating excessive quantities of data. The technique can be used to image modes in the MHz range opening up the possibility of spectrally filtered high resolution imaging of MHD instabilities that produce sufficient light fluctuations. Some examples of projection images of plasma fluctuations on the H-1NF heliac obtained using this approach are presented here.

  13. CHOROIDAL IMAGING USING SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY

    Science.gov (United States)

    Regatieri, Caio V.; Branchini, Lauren; Fujimoto, James G.; Duker, Jay S.

    2012-01-01

    Background A structurally and functionally normal choroidal vasculature is essential for retinal function. Therefore, a precise clinical understanding of choroidal morphology should be important for understanding many retinal and choroidal diseases. Methods PUBMED (http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed) was used for most of the literature search for this article. The criterion for inclusion of an article in the references for this review was that it included materials about both the clinical and the basic properties of choroidal imaging using spectral-domain optical coherence tomography. Results Recent reports show successful examination and accurate measurement of choroidal thickness in normal and pathologic states using spectral-domain optical coherence tomography systems. This review focuses on the principles of the new technology that make choroidal imaging using optical coherence tomography possible and on the changes that subsequently have been documented to occur in the choroid in various diseases. Additionally, it outlines future directions in choroidal imaging. Conclusion Optical coherence tomography is now proven to be an effective noninvasive tool to evaluate the choroid and to detect choroidal changes in pathologic states. Additionally, choroidal evaluation using optical coherence tomography can be used as a parameter for diagnosis and follow-up. PMID:22487582

  14. Application of optical coherence tomography based microangiography for cerebral imaging

    Science.gov (United States)

    Baran, Utku; Wang, Ruikang K.

    2016-03-01

    Requirements of in vivo rodent brain imaging are hard to satisfy using traditional technologies such as magnetic resonance imaging and two-photon microscopy. Optical coherence tomography (OCT) is an emerging tool that can easily reach at high speeds and provide high resolution volumetric images with a relatively large field of view for rodent brain imaging. Here, we provide the overview of recent developments of functional OCT based imaging techniques for neuroscience applications on rodents. Moreover, a summary of OCT-based microangiography (OMAG) studies for stroke and traumatic brain injury cases on rodents are provided.

  15. The Coherent X-ray Imaging (CXI) Instrument at the Linac Coherent Light Source (LCLS)

    Energy Technology Data Exchange (ETDEWEB)

    Boutet, Sebastien; Williams, Garth J.; /SLAC

    2011-08-16

    The Linac Coherent Light Source (LCLS) has become the first ever operational hard X-ray Free Electron Laser in 2009. It will operate as a user facility capable of delivering unique research opportunities in multiple fields of science. The LCLS and the LCLS Ultrafast Science Instruments (LUSI) construction projects are developing instruments designed to make full use of the capabilities afforded by the LCLS beam. One such instrument is being designed to utilize the LCLS coherent beam to image with high resolution any sub-micron object. This instrument is called the Coherent X-ray Imaging (CXI) instrument. This instrument will provide a flexible optical system capable of tailoring key beam parameters for the users. A suite of shot-to-shot diagnostics will also be provided to characterize the beam on every pulse. The provided instrumentation will include multi-purpose sample environments, sample delivery and a custom detector capable of collecting 2D data at 120 Hz. In this article, the LCLS will be briefly introduced along with the technique of Coherent X-ray Diffractive Imaging (CXDI). A few examples of scientific opportunities using the CXI instrument will be described. Finally, the conceptual layout of the instrument will be presented along with a description of the key requirements for the overall system and specific devices required.

  16. Analog signal processing for optical coherence imaging systems

    Science.gov (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.

  17. Coherent multiple imaging by means of pupil plane filtering

    Science.gov (United States)

    Erdelyi, Miklos; Kroyan, Armen; Osvay, Karoly; Bor, Zsolt; Wilson, William L., Jr.; Smayling, Michael C.; Tittel, Frank K.

    1999-07-01

    A resolution enhancement technique suitable for Deep-UV microlithography based on coherent multiple imaging (CMI) will be described. We showed recently that a Fabry-Perot etalon inserted between the mask and the projection lens in an optical stepper is able to simultaneously enhance the resolution and depth of focus of an aerial image. Since the multiple images of the mask pattern created by the etalon are added together coherently, the final image profile is very sensitive to the initial phase conditions. It is possible to simulate this coherent multiple imaging techniques using a simulation model which either superimposes separate output electric fields or by applying an appropriate transmission-phase pupil plane filter in the simulator. The first approach, however, requires a modification of the simulation software which allows output of the electric field profile, while the second approach can be used with a conventional commercial lithography simulator. In this paper computer simulations for isolated and extended contact hole arrays are used to demonstrate that the CMI method can enhance resolution by 18 percent while maintaining or even increasing the DOF of the aerial image. It is also shown that the high intensity side lobes generated by the filter nc abe eliminated by means of a phase shifting mask or by reducing the spatial coherence of the illumination source. The optimum value of spatial coherence was found to be 0.28. In this case the side lobes disappear, and the intensity of the main peaks doubles. The impact of this technique on image intensity is also discussed.

  18. Imaging vascular implants with optical coherence tomography

    Science.gov (United States)

    Barton, Jennifer K.; Dal Ponte, Donny B.; Williams, Stuart K.; Ford, Bridget K.; Descour, Michael R.

    2000-04-01

    Vascular stents and grafts have many proven and promising clinical applications, but also a large number of complications. A focus of current research is the development of biocompatible implants. Evaluation of these devices generally requires a large number of animals due to the need for explanation and histological evaluation of the implant at several time intervals. It would be desirable to use instead a high resolution, in situ assessment method. An in vitro study was performed to determine if OCT could image cell proliferation and thrombus formation on vascular stents and grafts. First, images were taken of explanted stents. The implants were locate din peripheral vessels of a porcine model of atherosclerosis. The images clearly show the vessel response to initial damage, the materials of the implant, extent of intimal cell hyper proliferation, and small platelet aggregates. Next, a tissue engineered graft, which had been sodded with smooth muscle cells and incubated in a bioreactor, was evaluated. Cross-section images showed the pores of the polymer material and the layer of smooth muscle cells beginning to invade the graft material. For comparison, in vitro 20 MHz IVUS images of the same grafts were obtained. A catheter was designed for intravascular imaging. The 2.3 mm diameter catheter contains a fiber with GRIN lens and right angle prism, a monorail guidewire, and a novel positioning wire that can be protruded to push the catheter against the vessel wall, potentially eliminating the need for saline flush. Preliminary in vitro results with this catheter are encouraging.

  19. Optical coherence tomography-based micro-particle image velocimetry.

    Science.gov (United States)

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

    2013-11-15

    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.

  20. Improving resolution of optical coherence tomography for imaging of microstructures

    Science.gov (United States)

    Shen, Kai; Lu, Hui; Wang, James H.; Wang, Michael R.

    2015-03-01

    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.

  1. Optical Coherence Tomography for Brain Imaging

    Science.gov (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.

  2. Coherent Raman spectro-imaging with laser frequency combs

    CERN Document Server

    Ideguchi, Takuro; Bernhardt, Birgitta; Guelachvili, Guy; Picqué, Nathalie; Hänsch, Theodor W

    2013-01-01

    Optical spectroscopy and imaging of microscopic samples have opened up a wide range of applications throughout the physical, chemical, and biological sciences. High chemical specificity may be achieved by directly interrogating the fundamental or low-lying vibrational energy levels of the compound molecules. Amongst the available prevailing label-free techniques, coherent Raman scattering has the distinguishing features of high spatial resolution down to 200 nm and three-dimensional sectioning. However, combining fast imaging speed and identification of multiple - and possibly unexpected- compounds remains challenging: existing high spectral resolution schemes require long measurement times to achieve broad spectral spans. Here we overcome this difficulty and introduce a novel concept of coherent anti-Stokes Raman scattering (CARS) spectro-imaging with two laser frequency combs. We illustrate the power of our technique with high resolution (4 cm-1) Raman spectra spanning more than 1200 cm-1 recorded within le...

  3. Parametric imaging of viscoelasticity using optical coherence elastography

    Science.gov (United States)

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

    2015-03-01

    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.

  4. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging

    Science.gov (United States)

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

    2016-09-01

    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.

  5. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging.

    Science.gov (United States)

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

    2016-09-07

    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.

  6. Coherent fiber supercontinuum laser for nonlinear biomedical imaging

    DEFF Research Database (Denmark)

    Tu, Haohua; Liu, Yuan; Liu, Xiaomin;

    2012-01-01

    Nonlinear biomedical imaging has not benefited from the well-known techniques of fiber supercontinuum generation for reasons such as poor coherence (or high noise), insufficient controllability, low spectral power intensity, and inadequate portability. Fortunately, a few techniques involving...... nonlinear fiber optics and femtosecond fiber laser development have emerged to overcome these critical limitations. These techniques pave the way for conducting point-of-care nonlinear biomedical imaging by a low-maintenance cost-effective coherent fiber supercontinuum laser, which covers a broad emission...... wavelength of 350-1700 nm. A prototype of this laser has been demonstrated in label-free multimodal nonlinear imaging of cell and tissue samples.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only....

  7. Optical color-image encryption and synthesis using coherent diffractive imaging in the Fresnel domain.

    Science.gov (United States)

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

    2012-02-13

    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.

  8. 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

    2008-01-01

    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.

  9. Primate retina imaging with polarization-sensitive optical coherence tomography

    Science.gov (United States)

    Ducros, Mathieu G.; Marsack, Jason D.; Rylander, H. Grady; Thomsen, Sharon L.; Milner, Thomas E.

    2001-12-01

    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.

  10. Optical Coherence Tomography in Cancer Imaging

    Science.gov (United States)

    Nam, Ahhyun Stephanie; Vakoc, Benjamin; Blauvelt, David; Chico-Calero, Isabel

    Investigations into the biology of cancer and novel cancer therapies rely on preclinical mouse models and traditional histological endpoints. Drawbacks of this approach include a limit in the number of time points for evaluation and an increased number of animals per study. This has motivated the use of intravital microscopy, which can provide longitudinal imaging of critical tumor parameters. Here, the capabilities of OCT as an intravital microscopy of the tumor microenvironment are summarized, and the state of OCT adoption into cancer research is summarized.

  11. Coherent multiscale image processing using dual-tree quaternion wavelets.

    Science.gov (United States)

    Chan, Wai Lam; Choi, Hyeokho; Baraniuk, Richard G

    2008-07-01

    The dual-tree quaternion wavelet transform (QWT) is a new multiscale analysis tool for geometric image features. The QWT is a near shift-invariant tight frame representation whose coefficients sport a magnitude and three phases: two phases encode local image shifts while the third contains image texture information. The QWT is based on an alternative theory for the 2-D Hilbert transform and can be computed using a dual-tree filter bank with linear computational complexity. To demonstrate the properties of the QWT's coherent magnitude/phase representation, we develop an efficient and accurate procedure for estimating the local geometrical structure of an image. We also develop a new multiscale algorithm for estimating the disparity between a pair of images that is promising for image registration and flow estimation applications. The algorithm features multiscale phase unwrapping, linear complexity, and sub-pixel estimation accuracy.

  12. New variational image decomposition model for simultaneously denoising and segmenting optical coherence tomography images.

    Science.gov (United States)

    Duan, Jinming; Tench, Christopher; Gottlob, Irene; Proudlock, Frank; Bai, Li

    2015-11-21

    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.

  13. High-Speed Coherent Raman Fingerprint Imaging of Biological Tissues

    CERN Document Server

    Camp, Charles H; Heddleston, John M; Hartshorn, Christopher M; Walker, Angela R Hight; Rich, Jeremy N; Lathia, Justin D; Cicerone, Marcus T

    2014-01-01

    We have developed a coherent Raman imaging platform using broadband coherent anti-Stokes Raman scattering (BCARS) that provides an unprecedented combination of speed, sensitivity, and spectral breadth. The system utilizes a unique configuration of laser sources that probes the Raman spectrum over 3,000 cm$^{-1}$ and generates an especially strong response in the typically weak Raman "fingerprint" region through heterodyne amplification of the anti-Stokes photons with a large nonresonant background (NRB) while maintaining high spectral resolution of $<$ 13 cm$^{-1}$. For histology and pathology, this system shows promise in highlighting major tissue components in a non-destructive, label-free manner. We demonstrate high-speed chemical imaging in two- and three-dimensional views of healthy murine liver and pancreas tissues and interfaces between xenograft brain tumors and the surrounding healthy brain matter.

  14. Coherent Image Layout using an Adaptive Visual Vocabulary

    Energy Technology Data Exchange (ETDEWEB)

    Dillard, Scott E.; Henry, Michael J.; Bohn, Shawn J.; Gosink, Luke J.

    2013-03-06

    When querying a huge image database containing millions of images, the result of the query may still contain many thousands of images that need to be presented to the user. We consider the problem of arranging such a large set of images into a visually coherent layout, one that places similar images next to each other. Image similarity is determined using a bag-of-features model, and the layout is constructed from a hierarchical clustering of the image set by mapping an in-order traversal of the hierarchy tree into a space-filling curve. This layout method provides strong locality guarantees so we are able to quantitatively evaluate performance using standard image retrieval benchmarks. Performance of the bag-of-features method is best when the vocabulary is learned on the image set being clustered. Because learning a large, discriminative vocabulary is a computationally demanding task, we present a novel method for efficiently adapting a generic visual vocabulary to a particular dataset. We evaluate our clustering and vocabulary adaptation methods on a variety of image datasets and show that adapting a generic vocabulary to a particular set of images improves performance on both hierarchical clustering and image retrieval tasks.

  15. Coherent image layout using an adaptive visual vocabulary

    Science.gov (United States)

    Dillard, Scott E.; Henry, Michael J.; Bohn, Shawn; Gosink, Luke J.

    2013-03-01

    When querying a huge image database containing millions of images, the result of the query may still contain many thousands of images that need to be presented to the user. We consider the problem of arranging such a large set of images into a visually coherent layout, one that places similar images next to each other. Image similarity is determined using a bag-of-features model, and the layout is constructed from a hierarchical clustering of the image set by mapping an in-order traversal of the hierarchy tree into a space-filling curve. This layout method provides strong locality guarantees so we are able to quantitatively evaluate performance using standard image retrieval benchmarks. Performance of the bag-of-features method is best when the vocabulary is learned on the image set being clustered. Because learning a large, discriminative vocabulary is a computationally demanding task, we present a novel method for efficiently adapting a generic visual vocabulary to a particular dataset. We evaluate our clustering and vocabulary adaptation methods on a variety of image datasets and show that adapting a generic vocabulary to a particular set of images improves performance on both hierarchical clustering and image retrieval tasks.

  16. Three-dimensional coherence of the conscious body image.

    Science.gov (United States)

    Longo, Matthew R

    2015-01-01

    We experience our body as a coherent object in the three-dimensional (3-D) world. In contrast, the body is represented in somatosensory cortex as a fragmented collection of two-dimensional (2-D) maps. Recent results have suggested that some forms of higher level body representations maintain this fragmentation, for example by showing different patterns of distortion for two surfaces of a single body part, such as the palmar and dorsal hand surfaces. This study investigated the 3-D coherence of the conscious body image of the hand by comparing perceptual biases of perceived hand shape on the dorsal and palmar surfaces. Participants made forced-choice judgements of whether observed hand images were thinner or wider than their own left or right hand, and perceptual distortions of the hand image were assessed by fitting psychometric functions. The results suggested that the hand is consciously represented as a fully coherent, 3-D object. Specifically: (a) Similar overall levels of distortion were found on the palmar and dorsal hand surfaces, (b) comparable laterality effects were found on both surfaces (left hand represented as wider than right hand), and (c) the magnitude of distortions were strongly correlated across the two surfaces. Whereas other recent results have suggested that perceptual abilities such as position sense, tactile size perception, and tactile localization may rely on fragmented, 2-D representations of individual skin surfaces, the present results suggest that, in striking contrast, the conscious body image represents the body (or, at least the hand) as a coherent, 3-D object.

  17. Functional Doppler optical coherence tomography for cortical blood flow imaging

    Science.gov (United States)

    Yu, Lingfeng; Liu, Gangjun; Nguyen, Elaine; Choi, Bernard; Chen, Zhongping

    2010-02-01

    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.

  18. Molecular imaging true-colour spectroscopic optical coherence tomography

    Science.gov (United States)

    Robles, Francisco E.; Wilson, Christy; Grant, Gerald; Wax, Adam

    2011-12-01

    Molecular imaging holds a pivotal role in medicine due to its ability to provide invaluable insight into disease mechanisms at molecular and cellular levels. To this end, various techniques have been developed for molecular imaging, each with its own advantages and disadvantages. For example, fluorescence imaging achieves micrometre-scale resolution, but has low penetration depths and is mostly limited to exogenous agents. Here, we demonstrate molecular imaging of endogenous and exogenous chromophores using a novel form of spectroscopic optical coherence tomography. Our approach consists of using a wide spectral bandwidth laser source centred in the visible spectrum, thereby allowing facile assessment of haemoglobin oxygen levels, providing contrast from readily available absorbers, and enabling true-colour representation of samples. This approach provides high spectral fidelity while imaging at the micrometre scale in three dimensions. Molecular imaging true-colour spectroscopic optical coherence tomography (METRiCS OCT) has significant implications for many biomedical applications including ophthalmology, early cancer detection, and understanding fundamental disease mechanisms such as hypoxia and angiogenesis.

  19. Solving the Imaging Problem with Coherently Integrated Multiwavelength Data

    CERN Document Server

    Schmitt, H R; Armstrong, J T; Mozurkewich, D; Jorgensen, A M; Hindsley, R B; Tycner, C; Zavala, R T; Benson, J A; Hutter, D J

    2008-01-01

    Recovering images from optical interferometric observations is one of the major challenges in the field. Unlike the case of observations at radio wavelengths, in the optical the atmospheric turbulence changes the phases on a very short time scale, which results in corrupted phase measurements. In order to overcome these limitations, several groups developed image reconstruction techniques based only on squared visibility and closure phase information, which are unaffected by atmospheric turbulence. We present the results of two techniques used by our group, which employed coherently integrated data from the Navy Prototype Optical Interferometer. Based on these techniques we were able to recover complex visibilities for several sources and image them using standard radio imaging software. We describe these techniques, the corrections applied to the data, present the images of a few sources, and discuss the implications of these results.

  20. Density measurements using coherence imaging spectroscopy based on Stark broadeninga)

    Science.gov (United States)

    Lischtschenko, O.; Bystrov, K.; De Temmerman, G.; Howard, J.; Jaspers, R. J. E.; König, R.

    2010-10-01

    A coherence imaging camera has been set up at Pilot-PSI. The system is to be used for imaging the plasma density through the Stark effect broadening of the Hγ line. Local density values are then obtained by the Abel inversion of the measured interferometric fringe contrast. This report will present the instrument setup and proof-of-principle demonstration. The inverted spatial electron density profiles obtained near the cascaded arc source of Pilot-PSI in discharges with axial magnetic field of B=0.4 T are compared with an independent measurement of electron density by Thomson scattering and good agreement is found.

  1. Density measurements using coherence imaging spectroscopy based on Stark broadening

    Energy Technology Data Exchange (ETDEWEB)

    Lischtschenko, O.; Bystrov, K.; De Temmerman, G. [Association EURATOM-FOM, FOM-Institute for Plasma Physics Rijnhuizen, partner in the Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Howard, J. [Research Laboratory, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Jaspers, R. J. E. [Fusion Group, Eindhoven University of Technology, Postbus 513, 5600 MB Eindhoven (Netherlands); Koenig, R. [EURATOM Association, Max-Planck-Institut fuer Plasmaphysik, TI Greifswald, Wendelsteinstr.1, D-17491 Greifswald (Germany)

    2010-10-15

    A coherence imaging camera has been set up at Pilot-PSI. The system is to be used for imaging the plasma density through the Stark effect broadening of the H{sub {gamma}} line. Local density values are then obtained by the Abel inversion of the measured interferometric fringe contrast. This report will present the instrument setup and proof-of-principle demonstration. The inverted spatial electron density profiles obtained near the cascaded arc source of Pilot-PSI in discharges with axial magnetic field of B=0.4 T are compared with an independent measurement of electron density by Thomson scattering and good agreement is found.

  2. Interferometric Synthetic Aperture Microscopy: Computed Imaging for Scanned Coherent Microscopy

    Directory of Open Access Journals (Sweden)

    Stephen A. Boppart

    2008-06-01

    Full Text Available Three-dimensional image formation in microscopy is greatly enhanced by the use of computed imaging techniques. In particular, Interferometric Synthetic Aperture Microscopy (ISAM allows the removal of out-of-focus blur in broadband, coherent microscopy. Earlier methods, such as optical coherence tomography (OCT, utilize interferometric ranging, but do not apply computed imaging methods and therefore must scan the focal depth to acquire extended volumetric images. ISAM removes the need to scan the focus by allowing volumetric image reconstruction from data collected at a single focal depth. ISAM signal processing techniques are similar to the Fourier migration methods of seismology and the Fourier reconstruction methods of Synthetic Aperture Radar (SAR. In this article ISAM is described and the close ties between ISAM and SAR are explored. ISAM and a simple strip-map SAR system are placed in a common mathematical framework and compared to OCT and radar respectively. This article is intended to serve as a review of ISAM, and will be especially useful to readers with a background in SAR.

  3. Ultrasound harmonic enhanced imaging using eigenspace-based coherence factor.

    Science.gov (United States)

    Guo, Wei; Wang, Yuanyuan; Yu, Jinhua

    2016-12-01

    Tissue harmonic imaging (THI) utilizes harmonic signals generating within the tissue as the result of nonlinear acoustic wave propagation. With inadequate transmitting acoustic energy, THI is incapable to detect the small objects since poor harmonic signals have been generated. In most cases, high transmission energy cannot be guaranteed because of the imaging safety issue or specific imaging modality such as the plane wave imaging (PWI). Discrimination of small point targets such as calcification, however, is particularly important in the ultrasound diagnosis. Few efforts have been made to pursue the THI with high resolution and good small target visibility at the same time. In this paper, we proposed a new eigenspace-based coherence factor (ESBCF) beamformer to solve this problem. A new kind of coherence factor (CF), named as ESBCF, is firstly proposed to detect the point targets. The detected region-of-interest (ROI) is then enhanced adaptively by using a newly developed beamforming method. The ESBCF combines the information from signal eigenspace and coherence factor by expanding the CF to the covariance matrix of signal. Analogous to the image processing but in the radio frequency (RF) data domain, the proposed method fully utilizes the information from the fundamental and harmonic components. The performance of the proposed method is demonstrated by simulation and phantom experiments. The improvement of the point contrast ratio (PCR) is 7.6dB in the simulated data, and 6.0dB in the phantom experiment. Thanks to the improved small point detection ability of the ESBCF, the proposed beamforming algorithm can enhance the PCR considerably and maintain the high resolution of the THI at the same time. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Imaging of Phase Objects using Partially Coherent Illumination

    Energy Technology Data Exchange (ETDEWEB)

    Ravizza, F. L. [Univ. of Arizona, Tucson, AZ (United States)

    2013-01-01

    Screening high-power laser optics for light intensifying phase objects that cause laserinduced damage on downstream optics is critical to sustaining laser operation. Identifying such flaws on large-apertures is quite challenging since they are relatively small and invisible to conventional inspection methods. A Linescan Phase Differential Imaging (LPDI) system was developed to rapidly identify these flaws on large-aperture optics within a single full-aperture dark-field image. We describe a two-step production phase object screening process consisting of LPDI mapping and image analysis, followed by high-resolution interferometry and propagation based evaluation of the downstream damage potential of identified flaws. An image simulation code capable of modeling the LPDI partially coherent illumination was used to optimize its phase object sensitivity.

  5. Compressed sensing sparse reconstruction for coherent field imaging

    Science.gov (United States)

    Bei, Cao; Xiu-Juan, Luo; Yu, Zhang; Hui, Liu; Ming-Lai, Chen

    2016-04-01

    Return signal processing and reconstruction plays a pivotal role in coherent field imaging, having a significant influence on the quality of the reconstructed image. To reduce the required samples and accelerate the sampling process, we propose a genuine sparse reconstruction scheme based on compressed sensing theory. By analyzing the sparsity of the received signal in the Fourier spectrum domain, we accomplish an effective random projection and then reconstruct the return signal from as little as 10% of traditional samples, finally acquiring the target image precisely. The results of the numerical simulations and practical experiments verify the correctness of the proposed method, providing an efficient processing approach for imaging fast-moving targets in the future. Project supported by the National Natural Science Foundation of China (Grant No. 61505248) and the Fund from Chinese Academy of Sciences, the Light of “Western” Talent Cultivation Plan “Dr. Western Fund Project” (Grant No. Y429621213).

  6. Laryngeal imaging with polarization-sensitive optical coherence tomography

    Science.gov (United States)

    Burns, James A.; Kim, Ki Hean; Anderson, R. Rox

    2011-03-01

    Objectives/Hypothesis: Optical coherence tomography (OCT), an imaging technology that provides crosssectional subsurface tissue structure images using backscattered light, is a promising noninvasive, imaging modality for in-vivo assessment of vocal fold layered microstructure. Polarization-sensitive OCT (PS-OCT) augments conventional OCT by detecting changes in the polarization state of reflected light. This study imaged various benign laryngeal pathologies in patients undergoing direct laryngoscopy under general anesthesia to determine whether PS-OCT would provide useful additional information about vocal fold microstructure and glottic surface pathology. Study Design:Prospective clinical trial. Methods: Eighteen patients who were undergoing microlaryngoscopy under general anesthesia for benign glottic disease were imaged bilaterally with OCT and PS-OCT (N=34 vocal folds). Intraoperative microphotography guided placement of the imaging probe. Normalappearing glottic tissue was also imaged if present. When clinically indicated, biopsy or complete removal of the lesion established histologic confirmation. Results: PS-OCT provided high quality, vertical, cross-sectional images up to 1.2mm deep that complemented microlaryngoscopy, and conventional OCT for vocal fold pathologies. Scar tissue was visualized by PS-OCT, characterized by a birefringence pattern more intense than that of normal glottic tissue. Conclusions: Combining PS-OCT with OCT during human vocal cord imaging provides useful information in characterizing vocal cord lesions, particularly scar tissue.

  7. Pulse-compression ghost imaging lidar via coherent detection

    CERN Document Server

    Deng, Chenjin; Han, Shensheng

    2016-01-01

    Ghost imaging (GI) lidar, as a novel remote sensing technique,has been receiving increasing interest in recent years. By combining pulse-compression technique and coherent detection with GI, we propose a new lidar system called pulse-compression GI lidar. Our analytical results, which are backed up by numerical simulations, demonstrate that pulse-compression GI lidar can obtain the target's spatial intensity distribution, range and moving velocity. Compared with conventional pulsed GI lidar system, pulse-compression GI lidar, without decreasing the range resolution, is easy to obtain high single pulse energy with the use of a long pulse, and the mechanism of coherent detection can eliminate the influence of the stray light, which can dramatically improve the detection sensitivity and detection range.

  8. Pulse-compression ghost imaging lidar via coherent detection.

    Science.gov (United States)

    Deng, Chenjin; Gong, Wenlin; Han, Shensheng

    2016-11-14

    Ghost imaging (GI) lidar, as a novel remote sensing technique, has been receiving increasing interest in recent years. By combining pulse-compression technique and coherent detection with GI, we propose a new lidar system called pulse-compression GI lidar. Our analytical results, which are backed up by numerical simulations, demonstrate that pulse-compression GI lidar can obtain the target's spatial intensity distribution, range and moving velocity. Compared with conventional pulsed GI lidar system, pulse-compression GI lidar, without decreasing the range resolution, is easy to obtain high single pulse energy with the use of a long pulse, and the mechanism of coherent detection can eliminate the influence of the stray light, which is helpful to improve the detection sensitivity and detection range.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    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...

  10. Optical coherence tomography for embryonic imaging: a review

    Science.gov (United States)

    Raghunathan, Raksha; Singh, Manmohan; Dickinson, Mary E.; Larin, Kirill V.

    2016-05-01

    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.

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    , 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......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...... 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...

  12. Imaging of oral pathological tissue using optical coherence tomography

    Science.gov (United States)

    Canjau, Silvana; Todea, Carmen; Sinescu, Cosmin; Duma, Virgil-Florin; Topala, Florin I.; Podoleanu, Adrian G.

    2014-01-01

    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.

  13. Imaging properties of coherent anti-Stokes Raman scattering microscope

    Institute of Scientific and Technical Information of China (English)

    Yuan Jing-He; Xiao Fan-Rong; Wang Gui-Ying; Xu Zhi-Zhan

    2005-01-01

    The coherent anti-Stokes Raman scattering (CARS) microscope with the combination of confocal and CARS techniques is a remarkable alternative for imaging chemical or biological specimens that neither fluoresce nor tolerate labelling. CARS is a nonlinear optical process, the imaging properties of CARS microscopy will be very different from the conventional confocal microscope. In this paper, the intensity distribution and the polarization property of the optical field near the focus was calculated. By using the Green function, the precise analytic solution to the wave equation of a Hertzian dipole source was obtained. We found that the intensity distributions vary considerably with the different experimental configurations and the different specimen shapes. So the conventional description of microscope (e.g. the point spread function) will fail to describe the imaging properties of the CARS microscope.

  14. Imaging port wine stains by fiber optical coherence tomography

    Science.gov (United States)

    Zhao, Shiyong; Gu, Ying; Xue, Ping; Guo, Jin; Shen, Tingmei; Wang, Tianshi; Huang, Naiyan; Zhang, Li; Qiu, Haixia; Yu, Xin; Wei, Xunbin

    2010-05-01

    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.

  15. Flow measurement using speckle in optical coherence tomography images

    Science.gov (United States)

    Barton, Jennifer K.; Stromski, Steven

    2005-04-01

    Doppler optical coherence tomography (DOCT) is a valuable tool for depth-resolved flow measurements in tissue. However, DOCT suffers from two disadvantages: it is insensitive to flow in the direction normal to the imaging beam, and it requires knowledge of the phase of the demodulated signal. We present an alternative method of extracting flow information, using speckle of conventional amplitude optical coherence tomography images. The two techniques can be shown to be essentially equivalent, with the distinction that speckle methods are sensitive to flow in all directions but do not provide information on the direction of flow. It is well known in other imaging modalities that moving scatterers cause a time-varying speckle pattern. Due to the pixel-by-pixel acquisition scheme of conventional OCT, time-varying speckle is manifested as a change of OCT image spatial speckle frequencies. We tested the ability of speckle to provide quantitative flow information using a flow phantom (a tube filled with Intralipid flowing at a constant volumetric flow rate). Initially, m-scans were taken at over the center of the tube. Images were averaged to reduce noise and the region corresponding to the center one-quarter of the tube lumen was selected. Sequential a-scans were concatenated, the Fourier transform performed, and a ratio of high to low spatial frequencies computed. We found that, over a range of velocities, this ratio bore a linear relation to flow velocity. For two-dimensional imaging, the program was modified to use a sliding window. Parabolic flow profile was visualized inside the tube. This study shows the feasibility of extracting quantitative flow data in all directions without phase information.

  16. Imaging Cutaneous T-Cell Lymphoma with Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Hans Christian Ring

    2012-07-01

    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.

  17. Optical coherence tomography imaging of ocular and periocular tumours

    Science.gov (United States)

    Medina, Carlos A; Plesec, Thomas; Singh, Arun D

    2014-01-01

    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

  18. Image Inpainting Based on Coherence Transport with Adapted Distance Functions

    KAUST Repository

    März, Thomas

    2011-01-01

    We discuss an extension of our method image inpainting based on coherence transport. For the latter method the pixels of the inpainting domain have to be serialized into an ordered list. Until now, to induce the serialization we have used the distance to boundary map. But there are inpainting problems where the distance to boundary serialization causes unsatisfactory inpainting results. In the present work we demonstrate cases where we can resolve the difficulties by employing other distance functions which better suit the problem at hand. © 2011 Society for Industrial and Applied Mathematics.

  19. Three-dimensional multifunctional optical coherence tomography for skin imaging

    Science.gov (United States)

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

    2016-02-01

    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.

  20. Stokes-Doppler coherence imaging for ITER boundary tomography

    Science.gov (United States)

    Howard, J.; Kocan, M.; Lisgo, S.; Reichle, R.

    2016-11-01

    An optical coherence imaging system is presently being designed for impurity transport studies and other applications on ITER. The wide variation in magnetic field strength and pitch angle (assumed known) across the field of view generates additional Zeeman-polarization-weighting information that can improve the reliability of tomographic reconstructions. Because background reflected light will be somewhat depolarized analysis of only the polarized fraction may be enough to provide a level of background suppression. We present the principles behind these ideas and some simulations that demonstrate how the approach might work on ITER. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization.

  1. Coherent hollow-core waveguide bundles for thermal imaging.

    Science.gov (United States)

    Gal, Udi; Harrington, James; Ben-David, Moshe; Bledt, Carlos; Syzonenko, Nicholas; Gannot, Israel

    2010-09-01

    There has been very little work done in the past to extend the wavelength range of fiber image bundles to the IR range. This is due, in part, to the lack of IR transmissive fibers with optical and mechanical properties analogous to the oxide glass fibers currently employed in the visible fiber bundles. Our research is aimed at developing high-resolution hollow-core coherent IR fiber bundles for transendoscopic infrared imaging. We employ the hollow glass waveguide (HGW) technology that was used successfully to make single-HGWs with Ag/AgI thin film coatings to form coherent bundles for IR imaging. We examine the possibility of developing endoscopic systems to capture thermal images using hollow waveguide fiber bundles adjusted to the 8-10?mum spectral range and investigate the applicability of such systems. We carried out a series of measurements in order to characterize the optical properties of the fiber bundles. These included the attenuation, resolution, and temperature response. We developed theoretical models and simulation tools that calculate the light propagation through HGW bundles, and which can be used to calculate the optical properties of the fiber bundles. Finally, the HGW fiber bundles were used to transmit thermal images of various heated objects; the results were compared with simulation results. The experimental results are encouraging, show an improvement in the resolution and thermal response of the HGW fiber bundles, and are consistent with the theoretical results. Nonetheless, additional improvements in the attenuation of the bundles are required in order to be able to use this technology for medical applications.

  2. Optical coherence tomography: imaging of the choroid and beyond.

    Science.gov (United States)

    Mrejen, Sarah; Spaide, Richard F

    2013-01-01

    Seventy percent of the blood flow to the eye goes to the choroid, a structure that is vitally important to the function of the retina. The in vivo structure of the choroid in health and disease is incompletely visualized with traditional imaging modalities, including indocyanine green angiography, ultrasonography, and spectral domain optical coherence tomography (OCT). Use of new OCT modalities, including enhanced depth imaging OCT, image averaging, and swept-source OCT, have led to increased visualization of the choroidal anatomy. The correlation of these new anatomical findings with other imaging modalities results increases understanding of many eye diseases and recognises of new ones. The status of the choroid appears to be a crucial determinant in the pathogenesis of diseases such as age-related choroidal atrophy, myopic chorioretinal atrophy, central serous chorioretinopathy, chorioretinal inflammatory diseases, and tumors. Extension of these imaging techniques has provided insights into abnormalities of the sclera and optic nerve. Future developments will include blood flow information, 3D rendering of various ocular structures, and the ability to evaluate changes in 3D structural information over time (4D imaging). Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Multiparametric, longitudinal optical coherence tomography imaging reveals acute injury and chronic recovery in experimental ischemic stroke

    National Research Council Canada - National Science Library

    Srinivasan, Vivek J; Mandeville, Emiri T; Can, Anil; Blasi, Francesco; Climov, Mihail; Daneshmand, Ali; Lee, Jeong Hyun; Yu, Esther; Radhakrishnan, Harsha; Lo, Eng H; Sakadžić, Sava; Eikermann-Haerter, Katharina; Ayata, Cenk

    2013-01-01

    .... A multi-parametric Optical Coherence Tomography (OCT) platform for longitudinal imaging of ischemic stroke in mice, through thinned-skull, reinforced cranial window surgical preparations, is described...

  4. [Imaging port wine stain by optical coherence tomography].

    Science.gov (United States)

    Zhao, Shi-Yong; Yu, Xin; Qiu, Hai-Xia; Huang, Nai-Yan; Wang, Tian-Shi; Xue, Ping; Gu, Ying

    2010-12-01

    Optical coherence tomography is an appropriate imaging method for biomedical science, due to its advantages of noninvasive nature, high resolution and fast imaging speed. Because most biological tissues have the characteristic of high scattering coefficient, OCT system can just obtain the structural images several millimeters below the surface of the tissues. The superficial depth of OCT's penetration limits application in dermatology field. As a common disease, the port wine stain (PWS) is a indication of OCT, because of its superficial lesion and significant expansion of blood vessels. To get deeper penetration in the skin, the authors employed 1 310 nm superluminescent diode as light source, optimized the light intensity ratio of reference delay arm and sample arm and control polarization, and the research of PWS imaging in vivo was accomplished. Besides, OCT is able to gather clear image and key characteristic parameters, such as the depth of epidermis layer, the diameter of blood vessel, etc. OCT will play an important role in the diagnosis and therapy of PWS.

  5. Phase contrast imaging with coherent high energy X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Snigireva, I. [ESRF, Grenoble (France)

    1997-02-01

    X-ray imaging concern high energy domain (>6 keV) like a contact radiography, projection microscopy and tomography is used for many years to discern the features of the internal structure non destructively in material science, medicine and biology. In so doing the main contrast formation is absorption that makes some limitations for imaging of the light density materials and what is more the resolution of these techniques is not better than 10-100 {mu}m. It was turned out that there is now way in which to overcome 1{mu}m or even sub-{mu}m resolution limit except phase contrast imaging. It is well known in optics that the phase contrast is realised when interference between reference wave front and transmitted through the sample take place. Examples of this imaging are: phase contrast microscopy suggested by Zernike and Gabor (in-line) holography. Both of this techniques: phase contrast x-ray microscopy and holography are successfully progressing now in soft x-ray region. For imaging in the hard X-rays to enhance the contrast and to be able to resolve phase variations across the beam the high degree of the time and more importantly spatial coherence is needed. Because of this it was reasonable that the perfect crystal optics was involved like Bonse-Hart interferometry, double-crystal and even triple-crystal set-up using Laue and Bragg geometry with asymmetrically cut crystals.

  6. Robust image registration using adaptive coherent point drift method

    Science.gov (United States)

    Yang, Lijuan; Tian, Zheng; Zhao, Wei; Wen, Jinhuan; Yan, Weidong

    2016-04-01

    Coherent point drift (CPD) method is a powerful registration tool under the framework of the Gaussian mixture model (GMM). However, the global spatial structure of point sets is considered only without other forms of additional attribute information. The equivalent simplification of mixing parameters and the manual setting of the weight parameter in GMM make the CPD method less robust to outlier and have less flexibility. An adaptive CPD method is proposed to automatically determine the mixing parameters by embedding the local attribute information of features into the construction of GMM. In addition, the weight parameter is treated as an unknown parameter and automatically determined in the expectation-maximization algorithm. In image registration applications, the block-divided salient image disk extraction method is designed to detect sparse salient image features and local self-similarity is used as attribute information to describe the local neighborhood structure of each feature. The experimental results on optical images and remote sensing images show that the proposed method can significantly improve the matching performance.

  7. Optical coherence tomography image denoising using Gaussianization transform

    Science.gov (United States)

    Amini, Zahra; Rabbani, Hossein

    2017-08-01

    We demonstrate the power of the Gaussianization transform (GT) for modeling image content by applying GT for optical coherence tomography (OCT) denoising. The proposed method is a developed version of the spatially constrained Gaussian mixture model (SC-GMM) method, which assumes that each cluster of similar patches in an image has a Gaussian distribution. SC-GMM tries to find some clusters of similar patches in the image using a spatially constrained patch clustering and then denoise each cluster by the Wiener filter. Although in this method GMM distribution is assumed for the noisy image, holding this assumption on a dataset is not investigated. We illustrate that making a Gaussian assumption on a noisy dataset has a significant effect on denoising results. For this purpose, a suitable distribution for OCT images is first obtained and then GT is employed to map this original distribution of OCT images to a GMM distribution. Then, this Gaussianized image is used as the input of the SC-GMM algorithm. This method, which is a combination of GT and SC-GMM, remarkably improves the results of OCT denoising compared with earlier version of SC-GMM and even produces better visual and numerical results than the state-of-the art works in this field. Indeed, the main advantage of the proposed OCT despeckling method is texture preservation, which is important for main image processing tasks like OCT inter- and intraretinal layer analysis. Thus, to prove the efficacy of the proposed method for this analysis, an improvement in the segmentation of intraretinal layers using the proposed method as a preprocessing step is investigated. Furthermore, the proposed method can achieve the best expert ranking between other contending methods, and the results show the helpfulness and usefulness of the proposed method in clinical applications.

  8. Laparoscopic optical coherence tomographic imaging of human ovarian cancer

    Science.gov (United States)

    Hariri, Lida P.; Bonnema, Garret T.; Schmidt, Kathy; Korde, Vrushali; Winkler, Amy M.; Hatch, Kenneth; Brewer, Molly; Barton, Jennifer K.

    2009-02-01

    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.

  9. Lens-free coherent modulation imaging with collimated illumination

    Institute of Scientific and Technical Information of China (English)

    Hua Tao; Suhas P.Veetil; Xingchen Pan; Cheng Liu; Jianqiang Zhu

    2016-01-01

    We propose a lens-free coherent modulation imaging (CMI) method for reconstructing a general complex-valued wave field from a single frame of a diffraction pattern.A numerical Fourier transform is introduced in the iterative reconstruction process to replace the lens or zone plate used in the current CMI technique to adopt the constraint on the Fourier components of the exit wave field of the sample.While the complexity of the experimental setup is remarkably reduced by replacing the zone plate and additional accessories with the numerical processing,the energy fluence loss induced by the undesired diffraction orders of the zone plate can be also avoided.The feasibility of the proposed technique is verified experimentally with visible light.

  10. Coherent label-free imaging through turbidity: a holographic approach

    Science.gov (United States)

    Bianco, V.; Paturzo, M.; Marchesano, V.; Miccio, L.; Memmolo, P.; Ferraro, P.

    2016-03-01

    A challenging issue has to be faced in microscopy whenever samples are immersed inside a dynamic turbid medium, as occluding objects provoke severe light scattering or unpredictable time-variable phase delays that scramble the object information. In these cases, the transmission matrix of the medium cannot be fully characterized. Here we show a simple technique, named Multi-Look Digital Holography (MLDH), able to fully recover the useful signal of biological specimens dipped inside a turbid liquid phase. Multiple hologram recordings are incoherently combined to synthesize the whole complex field diffused by the sample, which is revealed through turbidity providing quantitative phase-contrast information. Moreover, we show that the presence of a turbid medium can have a positive effect on a coherent imaging system, helping to reduce the effect of speckle artifacts. In other words, occluding biological elements, like e.g. Red Blood Cells (RBCs), can be thought as useful optical components providing denoising capabilities.

  11. Optical coherence tomography for retinal imaging in multiple sclerosis

    Directory of Open Access Journals (Sweden)

    Zimmermann H

    2014-12-01

    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

  12. Surface imaging of metallic material fractures using optical coherence tomography.

    Science.gov (United States)

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

    2014-09-10

    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.

  13. All-optically integrated multimodality imaging system: combined photoacoustic microscopy, optical coherence tomography, and fluorescence imaging

    Science.gov (United States)

    Chen, Zhongjiang; Yang, Sihua; Xing, Da

    2016-10-01

    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.

  14. Micro- and nano-imaging at the diamond beamline I13L-imaging and coherence

    Energy Technology Data Exchange (ETDEWEB)

    Rau, C., E-mail: Christoph.rau@diamond.ac.uk [Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, OX 11 0DE (United Kingdom); University of Manchester, School of Materials Grosvenor St., Manchester, M1 7HS (United Kingdom); Northwestern University School of Medicine, 303 E. Chicago Avenue, Chicago, IL 60611-3008 (United States); Wagner, U. H.; Vila-Comamala, J.; Bodey, A.; Parson, A.; García-Fernández, M.; Pešić, Z.; Zanette, I. [Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, OX 11 0DE (United Kingdom); De Fanis, A. [Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, OX 11 0DE (United Kingdom); European XFEL GmbH, Notkestraße 85, 22607 Hamburg (Germany); Zdora, M. [Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, OX 11 0DE (United Kingdom); Department of Physics and Astronomy, University College London, London, WC1E 6BT (United Kingdom)

    2016-07-27

    The Diamond Beamline I13L is dedicated to imaging on the micron- and nano-lengthscale, operating in the energy range between 6 and 30 keV. For this purpose two independent stations have been built. The imaging branch is fully operational for micro-tomography and in-line phase contrast imaging with micrometer resolution. Currently a full-field microscope providing 50nm spatial resolution over a field of view of 100 µm is being tested. On the coherence branch, coherent diffraction imaging techniques such as ptychography and coherent X-ray Bragg diffraction are currently developed. The beamline contains a number of unique features. The machine layout has been modified to the so-called mini-beta scheme, providing significantly increased flux from the two canted undulators. New instrumental designs such as a robot arm for the detector in diffraction experiments have been employed. The imaging branch is operated in collaboration with Manchester University, called therefore the Diamond-Manchester Branchline.

  15. Coherent Raman dual-comb spectroscopy and imaging

    Science.gov (United States)

    Ideguchi, Takuro; Holzner, Simon; Bernhardt, Birgitta; Guelachvili, Guy; Hänsch, Theodor W.; Picqué, Nathalie

    2014-11-01

    The invention of the optical frequency comb technique has revolutionized the field of precision spectroscopy, providing a way to measure the absolute frequency of any optical transition. Since, frequency combs have become common equipment for frequency metrology. In the last decade, novel applications for the optical frequency comb have been demonstrated beyond its original purpose. Broadband molecular spectroscopy is one of those. One such technique of molecular spectroscopy with frequency combs, dual-comb Fourier transform spectroscopy provides short measurement times with resolution and accuracy. Two laser frequency combs with slightly different repetition frequencies generate pairs of pulses with a linearly-scanned delay between pulses in a pair. The system without moving parts mimics a fast scanning Fourier transform interferometer. The measurement speed may be several orders of magnitude faster than that of a Michelson-based Fourier transform spectrometer, which opens up new opportunities for broadband molecular spectroscopy. Recently, dual-comb spectroscopy has been extended to nonlinear phenomena. A broadband Raman spectrum of molecular fingerprints may be measured within a few tens of microseconds with coherent Raman dual-comb spectroscopy. Raster scanning the sample leads to hyperspectral images. This rapid and broadband label-free vibrational spectroscopy and imaging technique might provide new diagnostic methods in a variety of scientific and industrial fields.

  16. Optical coherence tomography: imaging architect for dermal microdialysis in psoriasis

    Science.gov (United States)

    O'Connell, M.-L.; O'Connor, W.; Ramsay, B.; Guihen, E.; Ho, W. L.; Leahy, M. J.

    2011-03-01

    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.

  17. Polarization sensitive spectroscopic optical coherence tomography for multimodal imaging

    Science.gov (United States)

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

    2015-03-01

    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.

  18. Retinal Imaging of Infants on Spectral Domain Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Anand Vinekar

    2015-01-01

    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.

  19. Low-voltage coherent electron imaging based on a single-atom electron

    OpenAIRE

    Chang, Wei-Tse; Lin, Chun-Yueh; Hsu, Wei-Hao; Chang, Mu-Tung; Chen, Yi-Sheng; Hwu, En-Te; Hwang, Ing-Shouh

    2015-01-01

    It has been a general trend to develop low-voltage electron microscopes due to their high imaging contrast of the sample and low radiation damage. Atom-resolved transmission electron microscopes with voltages as low as 15-40 kV have been demonstrated. However, achieving atomic resolution at voltages lower than 10 kV is extremely difficult. An alternative approach is coherent imaging or phase retrieval imaging, which requires a sufficiently coherent source and an adequately small detection are...

  20. Benefits of optical coherence tomography for imaging of skin diseases

    Directory of Open Access Journals (Sweden)

    Utz S.R.

    2015-09-01

    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. Speckle suppression and companion detection using coherent differential imaging

    CERN Document Server

    Bottom, Michael; Bartos, Randall D; Shelton, J Chris; Serabyn, Eugene

    2016-01-01

    Residual speckles due to aberrations arising from optical errors after the split between the wavefront sensor and the science camera path are the most significant barriers to imaging extrasolar planets. While speckles can be suppressed using the science camera in conjunction with the deformable mirror, this requires knowledge of the phase of the electric field in the focal plane. We describe a method which combines a coronagraph with a simple phase-shifting interferometer to measure and correct speckles in the full focal plane. We demonstrate its initial use on the Stellar Double Coronagraph at the Palomar Observatory. We also describe how the same hardware can be used to distinguish speckles from true companions by measuring the coherence of the optical field in the focal plane. We present results observing the brown dwarf HD 49197b with this technique, demonstrating the ability to detect the presence of a companion even when it is buried in the speckle noise, without the use of any standard "calibration" te...

  2. The Information Content of Aberrated- and Non Aberrated Images Generated by Coherently- or Incoherently Illuminated Objects

    NARCIS (Netherlands)

    Hoenders, Bernhard J.

    2010-01-01

    The calculation of the information content of an ideal image rests on two different mathematical approaches: The expansion of the field into either the a) coherent modes, or b) into the the sampling functions occurring at the r.h.s. of 1. The coherent mode approach leads to analytical results for a

  3. MR Imaging with Intermolecular Multiple quantum Coherences (iMQCs):Fundamental Questions and Potentials

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ Pursuit of new contrast in imaging has been the driving force behind many innovative applications of physics in medical MRI. Even though the use of intramolecular multiple quantum coherence in NMR spectroscopy has a long history, intermolecular multiple quantum coherence (iMQC) among spins on different molecules, such as protonproton iMQC in water, was considered impossible for many years.

  4. Fingerprint imaging from the inside of a finger with full-field optical coherence tomography

    Science.gov (United States)

    Auksorius, Egidijus; Boccara, A. Claude

    2015-01-01

    Imaging below fingertip surface might be a useful alternative to the traditional fingerprint sensing since the internal finger features are more reliable than the external ones. One of the most promising subsurface imaging technique is optical coherence tomography (OCT), which, however, has to acquire 3-D data even when a single en face image is required. This makes OCT inherently slow for en face imaging and produce unnecessary large data sets. Here we demonstrate that full-field optical coherence tomography (FF-OCT) can be used to produce en face images of sweat pores and internal fingerprints, which can be used for the identification purposes. PMID:26601009

  5. Ptychographic coherent x-ray diffractive imaging in the water window

    OpenAIRE

    Giewekemeyer, K.; Beckers, M.; Gorniak, T.; Grunze, M.; Salditt, T.; Rosenhahn, A.

    2011-01-01

    Coherent x-ray diffractive microscopy enables full reconstruction of the complex transmission function of an isolated object to diffraction-limited resolution without relying on any optical elements between the sample and detector. In combination with ptychography, also specimens of unlimited lateral extension can be imaged. Here we report on an application of ptychographic coherent diffractive imaging (PCDI) in the soft x-ray regime, more precisely in the so-called water wi...

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

    CERN Document Server

    Liu, Xue; Shahriar, M S

    2010-01-01

    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. The first demonstration of laser computed tomography achieved by Coherent Detection Imaging method for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Toida, Masahiro; Ichimura, Tsutomu (Research Development Corp. of Japan (JRDC), Sendai (Japan). Inaba Biophoton Project); Inaba, Humio

    1991-06-01

    The first successful imaging by laser absorption computed tomography of in vitro specimens has been achieved by means of the Coherent Detection Imaging (CDI) method realized with the optical heterodyne detection technique and image reconstruction from back projection of the data obtained via optical absorption measurements in a parallel beam geometry. (author).

  8. Coherent backscattering of inelastic photons from atoms and their mirror images

    CERN Document Server

    Moriya, P H; Teixeira, R Celistrino; Máximo, C E; Piovella, N; Bachelard, R; Kaiser, R; Courteille, Ph W

    2016-01-01

    Coherent backscattering is a coherence effect in the propagation of waves through disordered media involving two or more scattering events. Here, we report on the observation of coherent backscattering from individual atoms and their mirror images. This system displays two important advantages: First, the effect can be observed at low optical densities, which allows to work in very dilute clouds or far from resonance. Second, due to the fact that the radiation of an atom interferes constructively with that of its own image, the phenomenon is much more robust to dephasing induced by strong saturation. In particular, the contribution of inelastically scattered photons to the interference process is demonstrated.

  9. Smart optical coherence tomography for ultra-deep imaging through highly scattering media

    CERN Document Server

    Badon, Amaury; Lerosey, Geoffroy; Boccara, Albert C; Fink, Mathias; Aubry, Alexandre

    2015-01-01

    Multiple scattering of waves in disordered media is a nightmare whether it be for detection or imaging purposes. The best approach so far to get rid of multiple scattering is optical coherence tomography. It basically combines confocal microscopy and coherence time-gating to discriminate ballistic photons from a predominant multiple scattering background. Nevertheless, the imaging depth range remains limited to 1 mm at best in human soft tissues. Here we propose a matrix approach of optical imaging to push back this fundamental limit. By combining a matrix discrimination of ballistic waves and iterative time-reversal, we show both theoretically and experimentally an extension of the imaging-depth limit by at least a factor two compared to optical coherence tomography. In particular, the reported experiment demonstrates imaging through a strongly scattering layer from which only one reflected photon over 1000 billion is ballistic. This approach opens a new route towards ultra-deep tissue imaging.

  10. Optical Coherence Tomography: An Emerging Technology for Biomedical Imaging and Optical Biopsy

    OpenAIRE

    Fujimoto, James G.; Pitris, Costas; Boppart, Stephen A.; Brezinski, Mark E.

    2000-01-01

    Optical coherence tomography (OCT) is an emerging technology for performing high-resolution cross-sectional imaging. OCT is analogous to ultrasound imaging, except that it uses light instead of sound. OCT can provide cross-sectional images of tissue structure on the micron scale in situ and in real time. Using OCT in combination with catheters and endoscopes enables high-resolution intraluminal imaging of organ systems. OCT can function as a type of optical biopsy and is a powerful imaging te...

  11. Coherent diffraction and holographic imaging of individual biomolecules using low-energy electrons

    CERN Document Server

    Latychevskaia, Tatiana; Escher, Conrad; Fink, Hans-Werner

    2013-01-01

    Modern microscopy techniques are aimed at imaging an individual molecule at atomic resolution. Here we show that low-energy electrons with kinetic energies of 50-250 eV offer a possibility of overcome the problem of radiation damage, and obtaining images of individual biomolecules. Two experimental schemes for obtaining images of individual molecules, holography and coherent diffraction imaging, are discussed and compared. Images of individual molecules obtained by both techniques, using low-energy electrons, are shown.

  12. Image transfer with spatial coherence for aberration corrected transmission electron microscopes.

    Science.gov (United States)

    Hosokawa, Fumio; Sawada, Hidetaka; Shinkawa, Takao; Sannomiya, Takumi

    2016-08-01

    The formula of spatial coherence involving an aberration up to six-fold astigmatism is derived for aberration-corrected transmission electron microscopy. Transfer functions for linear imaging are calculated using the newly derived formula with several residual aberrations. Depending on the symmetry and origin of an aberration, the calculated transfer function shows characteristic symmetries. The aberrations that originate from the field's components, having uniformity along the z direction, namely, the n-fold astigmatism, show rotational symmetric damping of the coherence. The aberrations that originate from the field's derivatives with respect to z, such as coma, star, and three lobe, show non-rotational symmetric damping. It is confirmed that the odd-symmetric wave aberrations have influences on the attenuation of an image via spatial coherence. Examples of image simulations of haemoglobin and Si [211] are shown by using the spatial coherence for an aberration-corrected electron microscope.

  13. Toward Long Distance, Sub-diffraction Imaging Using Coherent Camera Arrays

    CERN Document Server

    Holloway, Jason; Sharma, Manoj Kumar; Matsuda, Nathan; Horstmeyer, Roarke; Cossairt, Oliver; Veeraraghavan, Ashok

    2015-01-01

    In this work, we propose using camera arrays coupled with coherent illumination as an effective method of improving spatial resolution in long distance images by a factor of ten and beyond. Recent advances in ptychography have demonstrated that one can image beyond the diffraction limit of the objective lens in a microscope. We demonstrate a similar imaging system to image beyond the diffraction limit in long range imaging. We emulate a camera array with a single camera attached to an X-Y translation stage. We show that an appropriate phase retrieval based reconstruction algorithm can be used to effectively recover the lost high resolution details from the multiple low resolution acquired images. We analyze the effects of noise, required degree of image overlap, and the effect of increasing synthetic aperture size on the reconstructed image quality. We show that coherent camera arrays have the potential to greatly improve imaging performance. Our simulations show resolution gains of 10x and more are achievabl...

  14. Choroidal vasculature characteristics based choroid segmentation for enhanced depth imaging optical coherence tomography images

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qiang; Niu, Sijie [School of Computer Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yuan, Songtao; Fan, Wen, E-mail: fanwen1029@163.com; Liu, Qinghuai [Department of Ophthalmology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029 (China)

    2016-04-15

    Purpose: In clinical research, it is important to measure choroidal thickness when eyes are affected by various diseases. The main purpose is to automatically segment choroid for enhanced depth imaging optical coherence tomography (EDI-OCT) images with five B-scans averaging. Methods: The authors present an automated choroid segmentation method based on choroidal vasculature characteristics for EDI-OCT images with five B-scans averaging. By considering the large vascular of the Haller’s layer neighbor with the choroid-sclera junction (CSJ), the authors measured the intensity ascending distance and a maximum intensity image in the axial direction from a smoothed and normalized EDI-OCT image. Then, based on generated choroidal vessel image, the authors constructed the CSJ cost and constrain the CSJ search neighborhood. Finally, graph search with smooth constraints was utilized to obtain the CSJ boundary. Results: Experimental results with 49 images from 10 eyes in 8 normal persons and 270 images from 57 eyes in 44 patients with several stages of diabetic retinopathy and age-related macular degeneration demonstrate that the proposed method can accurately segment the choroid of EDI-OCT images with five B-scans averaging. The mean choroid thickness difference and overlap ratio between the authors’ proposed method and manual segmentation drawn by experts were −11.43 μm and 86.29%, respectively. Conclusions: Good performance was achieved for normal and pathologic eyes, which proves that the authors’ method is effective for the automated choroid segmentation of the EDI-OCT images with five B-scans averaging.

  15. Choroidal vasculature characteristics based choroid segmentation for enhanced depth imaging optical coherence tomography images.

    Science.gov (United States)

    Chen, Qiang; Niu, Sijie; Yuan, Songtao; Fan, Wen; Liu, Qinghuai

    2016-04-01

    In clinical research, it is important to measure choroidal thickness when eyes are affected by various diseases. The main purpose is to automatically segment choroid for enhanced depth imaging optical coherence tomography (EDI-OCT) images with five B-scans averaging. The authors present an automated choroid segmentation method based on choroidal vasculature characteristics for EDI-OCT images with five B-scans averaging. By considering the large vascular of the Haller's layer neighbor with the choroid-sclera junction (CSJ), the authors measured the intensity ascending distance and a maximum intensity image in the axial direction from a smoothed and normalized EDI-OCT image. Then, based on generated choroidal vessel image, the authors constructed the CSJ cost and constrain the CSJ search neighborhood. Finally, graph search with smooth constraints was utilized to obtain the CSJ boundary. Experimental results with 49 images from 10 eyes in 8 normal persons and 270 images from 57 eyes in 44 patients with several stages of diabetic retinopathy and age-related macular degeneration demonstrate that the proposed method can accurately segment the choroid of EDI-OCT images with five B-scans averaging. The mean choroid thickness difference and overlap ratio between the authors' proposed method and manual segmentation drawn by experts were -11.43 μm and 86.29%, respectively. Good performance was achieved for normal and pathologic eyes, which proves that the authors' method is effective for the automated choroid segmentation of the EDI-OCT images with five B-scans averaging.

  16. Coded aperture coherent scatter imaging for breast cancer detection: a Monte Carlo evaluation

    Science.gov (United States)

    Lakshmanan, Manu N.; Morris, Robert E.; Greenberg, Joel A.; Samei, Ehsan; Kapadia, Anuj J.

    2016-03-01

    It is known that conventional x-ray imaging provides a maximum contrast between cancerous and healthy fibroglandular breast tissues of 3% based on their linear x-ray attenuation coefficients at 17.5 keV, whereas coherent scatter signal provides a maximum contrast of 19% based on their differential coherent scatter cross sections. Therefore in order to exploit this potential contrast, we seek to evaluate the performance of a coded- aperture coherent scatter imaging system for breast cancer detection and investigate its accuracy using Monte Carlo simulations. In the simulations we modeled our experimental system, which consists of a raster-scanned pencil beam of x-rays, a bismuth-tin coded aperture mask comprised of a repeating slit pattern with 2-mm periodicity, and a linear-array of 128 detector pixels with 6.5-keV energy resolution. The breast tissue that was scanned comprised a 3-cm sample taken from a patient-based XCAT breast phantom containing a tomosynthesis- based realistic simulated lesion. The differential coherent scatter cross section was reconstructed at each pixel in the image using an iterative reconstruction algorithm. Each pixel in the reconstructed image was then classified as being either air or the type of breast tissue with which its normalized reconstructed differential coherent scatter cross section had the highest correlation coefficient. Comparison of the final tissue classification results with the ground truth image showed that the coded aperture imaging technique has a cancerous pixel detection sensitivity (correct identification of cancerous pixels), specificity (correctly ruling out healthy pixels as not being cancer) and accuracy of 92.4%, 91.9% and 92.0%, respectively. Our Monte Carlo evaluation of our experimental coded aperture coherent scatter imaging system shows that it is able to exploit the greater contrast available from coherently scattered x-rays to increase the accuracy of detecting cancerous regions within the breast.

  17. Evaluation of spectral coherence estimation methods for endmembers selection in hyperspectral images

    Directory of Open Access Journals (Sweden)

    David Fernandes

    2005-08-01

    Full Text Available The right endmenbers choice is an important task in the hiperspectral image classification processes. Among several models that use the endmenbers there is the Linear Spectral Mixture (LSM. This model has been extensively used in the fractional abundance images estimation. This work proposes two semi supervised methods for endmenbers selection based in the spectral coherence selection, which is an extension of the correlation coefficient concept. Spectral samples associated to classes are choosed a priori. These candidate samples to endmembers are compared by its relative spectral coherence. A subset of samples with minimum relative coherence will be selected as final endmenbers. AVIRIS (Airborne Visible/InfraRed Imaging Spectrometer images are used to test and compare the proposed methods.

  18. Medical ultrasound imaging method combining minimum variance beamforming and general coherence factor

    Institute of Scientific and Technical Information of China (English)

    WU Wentao; PU Jie; LU Yi

    2012-01-01

    In medical ultrasound imaging field, in order to obtain high resolution and correct the phase errors induced by the velocity in-homogeneity of the tissue, a high-resolution medical ultrasound imaging method combining minimum variance beamforming and general coherence factor was presented. First, the data from the elements is delayed for focusing; then the multi-channel data is used for minimum variance beamforming; at the same time, the data is transformed from array space to beam space to calculate the general coherence factor; in the end, the general coherence factor is used to weight the results of minimum variance beamforming. The medical images are gotten by the imaging system. Experiments based on point object and anechoic cyst object are used to verify the proposed method. The results show the proposed method in the aspects of resolution, contrast and robustness is better than minimum variance beamforming and conventional beamforming.

  19. Utilizing broadband X-rays in a Bragg coherent X-ray diffraction imaging experiment

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Wonsuk; Liu, Wenjun; Harder, Ross; Xu, Ruqing; Fuoss, Paul H.; Hruszkewycz, Stephan O.

    2016-07-26

    A method is presented to simplify Bragg coherent X-ray diffraction imaging studies of complex heterogeneous crystalline materials with a two-stage screening/imaging process that utilizes polychromatic and monochromatic coherent X-rays and is compatible within situsample environments. Coherent white-beam diffraction is used to identify an individual crystal particle or grain that displays desired properties within a larger population. A three-dimensional reciprocal-space map suitable for diffraction imaging is then measured for the Bragg peak of interest using a monochromatic beam energy scan that requires no sample motion, thus simplifyingin situchamber design. This approach was demonstrated with Au nanoparticles and will enable, for example, individual grains in a polycrystalline material of specific orientation to be selected, then imaged in three dimensions while under load.

  20. An intelligent despeckling method for swept source optical coherence tomography images of skin

    Science.gov (United States)

    Adabi, Saba; Mohebbikarkhoran, Hamed; Mehregan, Darius; Conforto, Silvia; Nasiriavanaki, Mohammadreza

    2017-03-01

    Optical Coherence Optical coherence tomography is a powerful high-resolution imaging method with a broad biomedical application. Nonetheless, OCT images suffer from a multiplicative artefacts so-called speckle, a result of coherent imaging of system. Digital filters become ubiquitous means for speckle reduction. Addressing the fact that there still a room for despeckling in OCT, we proposed an intelligent speckle reduction framework based on OCT tissue morphological, textural and optical features that through a trained network selects the winner filter in which adaptively suppress the speckle noise while preserve structural information of OCT signal. These parameters are calculated for different steps of the procedure to be used in designed Artificial Neural Network decider that select the best denoising technique for each segment of the image. Results of training shows the dominant filter is BM3D from the last category.

  1. Utilizing broadband X-rays in a Bragg coherent X-ray diffraction imaging experiment.

    Science.gov (United States)

    Cha, Wonsuk; Liu, Wenjun; Harder, Ross; Xu, Ruqing; Fuoss, Paul H; Hruszkewycz, Stephan O

    2016-09-01

    A method is presented to simplify Bragg coherent X-ray diffraction imaging studies of complex heterogeneous crystalline materials with a two-stage screening/imaging process that utilizes polychromatic and monochromatic coherent X-rays and is compatible with in situ sample environments. Coherent white-beam diffraction is used to identify an individual crystal particle or grain that displays desired properties within a larger population. A three-dimensional reciprocal-space map suitable for diffraction imaging is then measured for the Bragg peak of interest using a monochromatic beam energy scan that requires no sample motion, thus simplifying in situ chamber design. This approach was demonstrated with Au nanoparticles and will enable, for example, individual grains in a polycrystalline material of specific orientation to be selected, then imaged in three dimensions while under load.

  2. Reduction in Edge-Ringing in Aberrated Images of Coherent Edge Objects by Multishaded Aperture

    Directory of Open Access Journals (Sweden)

    Venkanna Mekala

    2014-01-01

    Full Text Available The images of a straight edge in coherent illumination produced by an optical system with circular aperture and apodized with multiple filters have been studied. The most common problem encountered in the coherent-imaging techniques is the edge-ringing. To minimize the edge-ringing, multishaded aperture method has been proposed. Image intensity distribution curves are drawn and edge-ringing values are evaluated. The results are compared to that of the airy case with the use of single, double and triple filtering.

  3. Ultrahigh resolution optical coherence tomography imaging with a broadband superluminescent diode light source.

    Science.gov (United States)

    Ko, Tony; Adler, Desmond; Fujimoto, James; Mamedov, Dmitry; Prokhorov, Viatcheslav; Shidlovski, Vladimir; Yakubovich, Sergei

    2004-05-17

    Ultrahigh resolution optical coherence tomography imaging is performed with a compact broadband superluminescent diode light source. The source consists of two multiplexed broadband superluminescent diodes and has a power output of 4 mW with a spectral bandwidth of 155 nm, centered at a wavelength of 890 nm. In vivo imaging was performed with approximately 2.3 microm axial resolution in scattering tissue and approximately 3.2 microm axial resolution in the retina. These results demonstrate that it is possible to perform in vivo ultrahigh resolution optical coherence tomography imaging using a superluminescent diode light source that is inexpensive, compact, and easy to operate.

  4. Three dimensional image reconstruction based on a wide-field optical coherence tomography system

    Science.gov (United States)

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

    2014-07-01

    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.

  5. Generalized eikonal of partially coherent beams and its use in quantitative imaging.

    Science.gov (United States)

    Gureyev, T E; Paganin, D M; Stevenson, A W; Mayo, S C; Wilkins, S W

    2004-08-06

    The generalized eikonal of a partially coherent paraxial wave is introduced via a differential equation describing the evolution of the time-averaged intensity. The theoretical formalism provides an analytical tool for the study of partially coherent imaging systems. It also makes possible quantitative phase retrieval and compositional mapping of weakly absorbing samples using phase-contrast imaging with broadband polychromatic radiation of known spectral distribution. An experimental demonstration is presented of the quantitative reconstruction of the projected thickness of a sample, given a phase-contrast image obtained using a polychromatic microfocus x-ray source.

  6. Dual-path handheld system for cornea and retina imaging using optical coherence tomography

    Science.gov (United States)

    Shirazi, Muhammad Faizan; Wijesinghe, Ruchire Eranga; Ravichandran, Naresh Kumar; Kim, Pilun; Jeon, Mansik; Kim, Jeehyun

    2016-11-01

    A dual-path handheld system is proposed for cornea and retina imaging using spectral domain optical coherence tomography. The handheld sample arm is designed to acquire two images simultaneously. Both eyes of a person can be imaged at the same time to obtain the images of the cornea of one eye and the retina of the other eye. Cornea, retina, and optic disc images are acquired with the proposed sample arm. Experimental results demonstrate the usefulness of this system for imaging of different eye segments. This system reduces the time required for imaging of the two eyes and is cost effective.

  7. Improved quality of optical coherence tomography imaging of basal cell carcinomas using speckle reduction

    DEFF Research Database (Denmark)

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

    2010-01-01

    BACKGROUND: Optical coherence tomography (OCT) is a possible imaging method for delineation of non-melanoma skin cancer. Speckle noise is the dominant noise contribution in OCT images; it limits the ability to identify cellular structures especially skin cancer. QUESTIONS ADDRESSED: This report...... suggests a method for improving OCT image quality for skin cancer imaging. EXPERIMENTAL DESIGN: OCT is an optical imaging method analogous to ultrasound. Two basal cell carcinomas (BCC) were imaged using an OCT speckle reduction technique (SR-OCT) based on repeated scanning by altering the distance between...... to a clinically relevant level when imaging BCC lesions....

  8. 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)

    2011-01-01

    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

  9. Nanoscale imaging with table-top coherent extreme ultraviolet source based on high harmonic generation

    Science.gov (United States)

    Ba Dinh, Khuong; Le, Hoang Vu; Hannaford, Peter; Van Dao, Lap

    2017-08-01

    A table-top coherent diffractive imaging experiment on a sample with biological-like characteristics using a focused narrow-bandwidth high harmonic source around 30 nm is performed. An approach involving a beam stop and a new reconstruction algorithm to enhance the quality of reconstructed the image is described.

  10. Final report: high resolution lensless 3D imaging of nanostructures with coherent x-rays

    Energy Technology Data Exchange (ETDEWEB)

    Jacobsen, Chris [Stony Brook Univ., NY (United States). Dept. of Physics and Astronomy

    2011-04-14

    This project helped pioneer the core capabilities of coherent diffraction imaging (CDI) using X rays at synchrotron light source facilities. We developed an apparatus that was used for CDI at the Advanced Light Source, and applied it to 2D and 3D imaging of nanostructures. We also explored a number of conceptual and computational issues on the reconstruction of CDI data.

  11. 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.

    2008-01-01

    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...

  12. Automatic segmentation of the choroid in enhanced depth imaging optical coherence tomography images.

    Science.gov (United States)

    Tian, Jing; Marziliano, Pina; Baskaran, Mani; Tun, Tin Aung; Aung, Tin

    2013-03-01

    Enhanced Depth Imaging (EDI) optical coherence tomography (OCT) provides high-definition cross-sectional images of the choroid in vivo, and hence is used in many clinical studies. However, the quantification of the choroid depends on the manual labelings of two boundaries, Bruch's membrane and the choroidal-scleral interface. This labeling process is tedious and subjective of inter-observer differences, hence, automatic segmentation of the choroid layer is highly desirable. In this paper, we present a fast and accurate algorithm that could segment the choroid automatically. Bruch's membrane is detected by searching the pixel with the biggest gradient value above the retinal pigment epithelium (RPE) and the choroidal-scleral interface is delineated by finding the shortest path of the graph formed by valley pixels using Dijkstra's algorithm. The experiments comparing automatic segmentation results with the manual labelings are conducted on 45 EDI-OCT images and the average of Dice's Coefficient is 90.5%, which shows good consistency of the algorithm with the manual labelings. The processing time for each image is about 1.25 seconds.

  13. Multiparametric, Longitudinal Optical Coherence Tomography Imaging Reveals Acute Injury and Chronic Recovery in Experimental Ischemic Stroke: e71478

    National Research Council Canada - National Science Library

    Vivek J Srinivasan; Emiri T Mandeville; Anil Can; Francesco Blasi; Mihail Climov; Ali Daneshmand; Jeong Hyun Lee; Esther Yu; Harsha Radhakrishnan; Eng H Lo; Sava Sakadzic; Katharina Eikermann-Haerter; Cenk Ayata

    2013-01-01

    .... A multi-parametric Optical Coherence Tomography (OCT) platform for longitudinal imaging of ischemic stroke in mice, through thinned-skull, reinforced cranial window surgical preparations, is described...

  14. Domain and range decomposition methods for coded aperture x-ray coherent scatter imaging

    Science.gov (United States)

    Odinaka, Ikenna; Kaganovsky, Yan; O'Sullivan, Joseph A.; Politte, David G.; Holmgren, Andrew D.; Greenberg, Joel A.; Carin, Lawrence; Brady, David J.

    2016-05-01

    Coded aperture X-ray coherent scatter imaging is a novel modality for ascertaining the molecular structure of an object. Measurements from different spatial locations and spectral channels in the object are multiplexed through a radiopaque material (coded aperture) onto the detectors. Iterative algorithms such as penalized expectation maximization (EM) and fully separable spectrally-grouped edge-preserving reconstruction have been proposed to recover the spatially-dependent coherent scatter spectral image from the multiplexed measurements. Such image recovery methods fall into the category of domain decomposition methods since they recover independent pieces of the image at a time. Ordered subsets has also been utilized in conjunction with penalized EM to accelerate its convergence. Ordered subsets is a range decomposition method because it uses parts of the measurements at a time to recover the image. In this paper, we analyze domain and range decomposition methods as they apply to coded aperture X-ray coherent scatter imaging using a spectrally-grouped edge-preserving regularizer and discuss the implications of the increased availability of parallel computational architecture on the choice of decomposition methods. We present results of applying the decomposition methods on experimental coded aperture X-ray coherent scatter measurements. Based on the results, an underlying observation is that updating different parts of the image or using different parts of the measurements in parallel, decreases the rate of convergence, whereas using the parts sequentially can accelerate the rate of convergence.

  15. Spectrum multiplexing and coherent-state decomposition in Fourier ptychographic imaging

    CERN Document Server

    Dong, Siyuan; Nanda, Pariksheet; Zheng, Guoan

    2014-01-01

    Information multiplexing is important for biomedical imaging and chemical sensing. In this paper, we report a microscopy imaging technique, termed state-multiplexed Fourier ptychography (FP), for information multiplexing and coherent-state decomposition. Similar to a typical Fourier ptychographic setting, we use an array of light sources to illuminate the sample from different incident angles and acquire corresponding low-resolution images using a monochromatic camera. In the reported technique, however, multiple light sources are lit up simultaneously for information multiplexing, and the acquired images thus represent incoherent summations of the sample transmission profiles corresponding to different coherent states. We show that, by using the state-multiplexed FP recovery routine, we can decompose the incoherent mixture of the FP acquisitions to recover a high-resolution sample image. We also show that, color-multiplexed imaging can be performed by simultaneously turning on R/G/B LEDs for data acquisition...

  16. Single particle imaging with soft x-rays at the Linac Coherent Light Source

    Science.gov (United States)

    Martin, Andrew V.; Andreasson, Jakob; Aquila, Andrew; Bajt, Saša; Barends, Thomas R. M.; Barthelmess, Miriam; Barty, Anton; Benner, W. Henry; Bostedt, Christoph; Bozek, John D.; Bucksbaum, Phillip; Caleman, Carl; Coppola, Nicola; DePonte, Daniel P.; Ekeberg, Tomas; Epp, Sascha W.; Erk, Benjamin; Farquar, George R.; Fleckenstein, Holger; Foucar, Lutz; Frank, Matthias; Gumprecht, Lars; Hampton, Christina Y.; Hantke, Max; Hartmann, Andreas; Hartmann, Elisabeth; Hartmann, Robert; Hau-Riege, Stephan P.; Hauser, Günther; Holl, Peter; Hoemke, André; Jönsson, Olof; Kassemeyer, Stephan; Kimmel, Nils; Kiskinova, Maya; Krasniqi, Faton; Krzywinski, Jacek; Liang, Mengning; Loh, Ne-Te Duane; Lomb, Lukas; Maia, Filipe R. N. C.; Marchesini, Stefano; Messerschmidt, Marc; Nass, Karol; Odic, Duško; Pedersoli, Emanuele; Reich, Christian; Rolles, Daniel; Rudek, Benedikt; Rudenko, Artem; Schmidt, Carlo; Schultz, Joachim; Seibert, M. Marvin; Shoeman, Robert L.; Sierra, Raymond G.; Soltau, Heike; Starodub, Dmitri; Steinbrener, Jan; Stellato, Francesco; Strüder, Lothar; Svenda, Martin; Tobias, Herbert; Ullrich, Joachim; Weidenspointner, Georg; Westphal, Daniel; White, Thomas A.; Williams, Garth; Hajdu, Janos; Schlichting, Ilme; Bogan, Michael J.; Chapman, Henry N.

    2011-06-01

    Results of coherent diffractive imaging experiments performed with soft X-rays (1-2 keV) at the Linac Coherent Light Source are presented. Both organic and inorganic nano-sized objects were injected into the XFEL beam as an aerosol focused with an aerodynamic lens. The high intensity and femtosecond duration of X-ray pulses produced by the Linac Coherent Light Source allow structural information to be recorded by X-ray diffraction before the particle is destroyed. Images were formed by using iterative methods to phase single shot diffraction patterns. Strategies for improving the reconstruction methods have been developed. This technique opens up exciting opportunities for biological imaging, allowing structure determination without freezing, staining or crystallization.

  17. Compound focusing mirror and X-ray waveguide optics for coherent imaging and nano-diffraction.

    Science.gov (United States)

    Salditt, Tim; Osterhoff, Markus; Krenkel, Martin; Wilke, Robin N; Priebe, Marius; Bartels, Matthias; Kalbfleisch, Sebastian; Sprung, Michael

    2015-07-01

    A compound optical system for coherent focusing and imaging at the nanoscale is reported, realised by high-gain fixed-curvature elliptical mirrors in combination with X-ray waveguide optics or different cleaning apertures. The key optical concepts are illustrated, as implemented at the Göttingen Instrument for Nano-Imaging with X-rays (GINIX), installed at the P10 coherence beamline of the PETRA III storage ring at DESY, Hamburg, and examples for typical applications in biological imaging are given. Characteristic beam configurations with the recently achieved values are also described, meeting the different requirements of the applications, such as spot size, coherence or bandwidth. The emphasis of this work is on the different beam shaping, filtering and characterization methods.

  18. Imaging actinic keratosis by high-definition optical coherence tomography. Histomorphologic correlation

    DEFF Research Database (Denmark)

    Boone, Marc A L M; Norrenberg, Sarah; Jemec, Gregor B E;

    2013-01-01

    transversal and axial directions, enable to visualize individual cells up to a depth of around 570 μm filling the imaging gap between conventional optical coherence tomography and reflectance confocal microscopy. We sought to determine the feasibility of detecting and grading of actinic keratosis...... by this technique using criteria defined for reflectance confocal microscopy compared to histology. In this pilot study, skin lesions of 17 patients with a histologically proven actinic keratosis were imaged by high-definition optical coherence tomography just before excision and images analysed qualitatively...... of photodamage. Using features already suggested by reflectance confocal microscopy, the study implies that high-definition optical coherence tomography facilitates in vivo diagnosis of actinic keratosis and allows the grading of different actinic keratosis lesions for increased clinical utility....

  19. Modulation of retinal image vasculature analysis to extend utility and provide secondary value from optical coherence tomography imaging.

    Science.gov (United States)

    Cameron, James R; Ballerini, Lucia; Langan, Clare; Warren, Claire; Denholm, Nicholas; Smart, Katie; MacGillivray, Thomas J

    2016-04-01

    Retinal image analysis is emerging as a key source of biomarkers of chronic systemic conditions affecting the cardiovascular system and brain. The rapid development and increasing diversity of commercial retinal imaging systems present a challenge to image analysis software providers. In addition, clinicians are looking to extract maximum value from the clinical imaging taking place. We describe how existing and well-established retinal vasculature segmentation and measurement software for fundus camera images has been modulated to analyze scanning laser ophthalmoscope retinal images generated by the dual-modality Heidelberg SPECTRALIS(®) instrument, which also features optical coherence tomography.

  20. Phase-Sensitive Coherence and the Classical-Quantum Boundary in Ghost Imaging

    Science.gov (United States)

    Erkmen, Baris I.; Hardy, Nicholas D.; Venkatraman, Dheera; Wong, Franco N. C.; Shapiro, Jeffrey H.

    2011-01-01

    The theory of partial coherence has a long and storied history in classical statistical optics. the vast majority of this work addresses fields that are statistically stationary in time, hence their complex envelopes only have phase-insensitive correlations. The quantum optics of squeezed-state generation, however, depends on nonlinear interactions producing baseband field operators with phase-insensitive and phase-sensitive correlations. Utilizing quantum light to enhance imaging has been a topic of considerable current interest, much of it involving biphotons, i.e., streams of entangled-photon pairs. Biphotons have been employed for quantum versions of optical coherence tomography, ghost imaging, holography, and lithography. However, their seemingly quantum features have been mimicked with classical-sate light, questioning wherein lies the classical-quantum boundary. We have shown, for the case of Gaussian-state light, that this boundary is intimately connected to the theory of phase-sensitive partial coherence. Here we present that theory, contrasting it with the familiar case of phase-insensitive partial coherence, and use it to elucidate the classical-quantum boundary of ghost imaging. We show, both theoretically and experimentally, that classical phase-sensitive light produces ghost imaging most closely mimicking those obtained in biphotons, and we derived the spatial resolution, image contrast, and signal-to-noise ratio of a standoff-sensing ghost imager, taking into account target-induced speckle.

  1. Phase-Sensitive Coherence and the Classical-Quantum Boundary in Ghost Imaging

    Science.gov (United States)

    Erkmen, Baris I.; Hardy, Nicholas D.; Venkatraman, Dheera; Wong, Franco N. C.; Shapiro, Jeffrey H.

    2011-01-01

    The theory of partial coherence has a long and storied history in classical statistical optics. the vast majority of this work addresses fields that are statistically stationary in time, hence their complex envelopes only have phase-insensitive correlations. The quantum optics of squeezed-state generation, however, depends on nonlinear interactions producing baseband field operators with phase-insensitive and phase-sensitive correlations. Utilizing quantum light to enhance imaging has been a topic of considerable current interest, much of it involving biphotons, i.e., streams of entangled-photon pairs. Biphotons have been employed for quantum versions of optical coherence tomography, ghost imaging, holography, and lithography. However, their seemingly quantum features have been mimicked with classical-sate light, questioning wherein lies the classical-quantum boundary. We have shown, for the case of Gaussian-state light, that this boundary is intimately connected to the theory of phase-sensitive partial coherence. Here we present that theory, contrasting it with the familiar case of phase-insensitive partial coherence, and use it to elucidate the classical-quantum boundary of ghost imaging. We show, both theoretically and experimentally, that classical phase-sensitive light produces ghost imaging most closely mimicking those obtained in biphotons, and we derived the spatial resolution, image contrast, and signal-to-noise ratio of a standoff-sensing ghost imager, taking into account target-induced speckle.

  2. Contribution of optical coherence tomography imaging in management of iatrogenic coronary dissection

    Energy Technology Data Exchange (ETDEWEB)

    Barber-Chamoux, Nicolas, E-mail: nbarber-chamoux@chu-clermontferrand.fr [Department of Cardiology, Gabriel Montpied University Hospital, Clermont-Ferrand (France); Souteyrand, Géraud; Combaret, Nicolas [Department of Cardiology, Gabriel Montpied University Hospital, Clermont-Ferrand (France); ISIT, CaVITI, CNRS (UMR-6284), Auvergne University, Clermont-Ferrand (France); Ouedraogo, Edgar; Lusson, Jean René [Department of Cardiology, Gabriel Montpied University Hospital, Clermont-Ferrand (France); Motreff, Pascal [Department of Cardiology, Gabriel Montpied University Hospital, Clermont-Ferrand (France); ISIT, CaVITI, CNRS (UMR-6284), Auvergne University, Clermont-Ferrand (France)

    2016-03-15

    Iatrogenic coronary dissection is a rare but potentially serious complication of coronary angiography and angioplasty. Treatment with angioplasty guided only by angiography is often difficult. Optical coherence tomography imaging seems to be an interesting technique to lead the management of iatrogenic coronary dissection. Diagnosis can be made by optical coherence tomography; it can also eliminate differential diagnosis. Furthermore, this technique can guide safely the endovascular treatment. - Highlights: • Iatrogenic coronary dissection remains a challenging problem in angiography. • Endocoronary imaging is helpful for the diagnosis of iatrogenic coronary dissection. • OCT is a safe option to manage the endovascular treatment of coronary dissection.

  3. OCT imaging with temporal dispersion induced intense and short coherence laser source

    Science.gov (United States)

    Manna, Suman K.; le Gall, Stephen; Li, Guoqiang

    2016-10-01

    Lower coherence length and higher intensity are two indispensable requirements on the light source for high resolution and large penetration depth OCT imaging. While tremendous interest is being paid on engineering various laser sources to enlarge their bandwidth and hence lowering the coherence length, here we demonstrate another approach by employing strong temporal dispersion onto the existing laser source. Cholesteric liquid crystal (CLC) cells with suitable dispersive slope at the edge of 1-D organic photonic band gap have been designed to provide maximum reduction in coherence volume while maintaining the intensity higher than 50%. As an example, the coherence length of a multimode He-Ne laser is reduced by more than 730 times.

  4. Tabletop Nanometer Extreme Ultraviolet Imaging in an Extended Reflection Mode using Coherent Fresnel Ptychography

    CERN Document Server

    Seaberg, Matthew D; Gardner, Dennis F; Shanblatt, Elisabeth R; Murnane, Margaret M; Kapteyn, Henry C; Adams, Daniel E

    2013-01-01

    We demonstrate high resolution extreme ultraviolet (EUV) coherent diffractive imaging in the most general reflection geometry by combining ptychography with tilted plane correction. This method makes it possible to image extended surfaces at any angle of incidence. Refocused light from a tabletop coherent high harmonic light source at 29 nm illuminates a nanopatterned surface at 45 degree angle of incidence. The reconstructed image contains quantitative amplitude and phase (in this case pattern height) information, comparing favorably with both scanning electron microscope and atomic force microscopy images. In the future, this approach will enable imaging of complex surfaces and nanostructures with sub-10 nm-spatial resolution and fs-temporal resolution, which will impact a broad range of nanoscience and nanotechnology including for direct application in actinic inspection in support of EUV lithography.

  5. Study on image feature extraction and classification for human colorectal cancer using optical coherence tomography

    Science.gov (United States)

    Huang, Shu-Wei; Yang, Shan-Yi; Huang, Wei-Cheng; Chiu, Han-Mo; Lu, Chih-Wei

    2011-06-01

    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. OCT (Optical coherence tomography) has been several advantages including high resolution and non-invasive cross-sectional image in vivo. In this study, we investigated the relationship between the B-scan OCT image features and histology of malignant human colorectal tissues, also en-face OCT image and the endoscopic image pattern. The in-vitro experiments were performed by a swept-source optical coherence tomography (SS-OCT) system; the swept source has a center wavelength at 1310 nm and 160nm in wavelength scanning range which produced 6 um axial resolution. In the study, the en-face images were reconstructed by integrating the axial values in 3D OCT images. The reconstructed en-face images show the same roundish or gyrus-like pattern with endoscopy images. The pattern of en-face images relate to the stages of colon cancer. Endoscopic OCT technique would provide three-dimensional imaging and rapidly reconstruct en-face images which can increase the speed of colon cancer diagnosis. Our results indicate a great potential for early detection of colorectal adenomas by using the OCT imaging.

  6. Collagen imaged by Coherent X-ray Diffraction: towards a complementary tool to conventional scanning SAXS

    Energy Technology Data Exchange (ETDEWEB)

    Berenguer de la Cuesta, Felisa; Bean, Richard J; Bozec, Laurent; Robinson, Ian K [London Centre for Nanotechnology (LCN), University College London (UCL), London WC1H 0AH (United Kingdom); McCallion, Catriona; Wallace, Kris [Department of Physics and Astronomy, University College London (UCL), London WC1E 6BT (United Kingdom); Hiller, Jen C; Terrill, Nicholas J, E-mail: f.berenguer@ucl.ac.u [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom)

    2010-10-01

    Third generation x-ray sources offer unique possibilities for exploiting coherence in the study of materials. New insights in the structure and dynamics of soft condensed matter and biological samples can be obtained by coherent x-ray diffraction (CXD). However, the experimental procedures for applying these methods to collagen tissues are still under development. We present here an investigation for the optimal procedure in order to obtain high quality CXD data from collagen tissues. Sample handling and preparation and adequate coherence defining apertures are among the more relevant factors to take into account. The impact of the results is also discussed, in particular in comparison with the information that can be extracted from conventional scanning small angle x-ray scattering (SAXS). Images of collagen tissues obtained by CXD reconstructions will give additional information about the local structure with higher resolution and will complement scanning SAXS images.

  7. Low-spatial-coherence broadband fiber source for speckle free imaging

    CERN Document Server

    Redding, Brandon; Mokan, Vadim; Seifert, Martin; Choma, Michael A; Cao, Hui

    2015-01-01

    We designed and demonstrate a fiber-based amplified spontaneous emission (ASE) source with low spatial coherence, low temporal coherence, and high power per mode. ASE is produced by optically pumping a large gain core multimode fiber while minimizing optical feedback to avoid lasing. The fiber ASE source provides 270 mW of continuous wave emission, centered at {\\lambda}=1055 nm with a full-width half-maximum bandwidth of 74 nm. The emission is distributed among as many as ~70 spatial modes, enabling efficient speckle suppression when combined with spectral compounding. Finally, we demonstrate speckle-free full field imaging using the fiber ASE source. The fiber ASE source provides a unique combination of high power per mode with both low spatial and low temporal coherence, making it an ideal source for full-field imaging and ranging applications.

  8. Low-spatial-coherence high-radiance broadband fiber source for speckle free imaging.

    Science.gov (United States)

    Redding, Brandon; Ahmadi, Peyman; Mokan, Vadim; Seifert, Martin; Choma, Michael A; Cao, Hui

    2015-10-15

    We design and demonstrate a fiber-based amplified spontaneous emission (ASE) source with low spatial coherence, low temporal coherence, and high power per mode. ASE is produced by optically pumping a large gain core multimode fiber while minimizing optical feedback to avoid lasing. The fiber ASE source provides 270 mW of continuous wave emission, centered at λ=1055  nm, with a full width at half-maximum bandwidth of 74 nm. The emission is distributed among as many as ∼70 spatial modes, enabling efficient speckle suppression when combined with spectral compounding. Finally, we demonstrate speckle-free full-field imaging using the fiber ASE source. The fiber ASE source provides a unique combination of high power per mode with both low spatial and low temporal coherence, making it an ideal source for full-field imaging and ranging applications.

  9. 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.

    2000-02-01

    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.

  10. Internal structure of an intact Convallaria majalis pollen grain observed with X-ray Fresnel coherent diffractive imaging

    NARCIS (Netherlands)

    Mancuso, Adrian P; Groves, Matthew R; Polozhentsev, Oleg E; Williams, Garth J; McNulty, Ian; Antony, Claude; Santarella-Mellwig, Rachel; Soldatov, Aleksander V; Lamzin, Victor; Peele, Andrew G; Nugent, Keith A; Vartanyants, Ivan A

    2012-01-01

    We have applied Fresnel Coherent Diffractive Imaging (FCDI) to image an intact pollen grain from Convallaria majalis. This approach allows us to resolve internal structures without the requirement to chemically treat or slice the sample into thin sections. Coherent X-ray diffraction data from this p

  11. Imaging of sub-wavelength structures radiating coherently near microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Maslov, Alexey V., E-mail: avmaslov@yandex.ru [University of Nizhny Novgorod, Nizhny Novgorod 603950 (Russian Federation); Astratov, Vasily N., E-mail: astratov@uncc.edu [Department of Physics and Optical Science, Center for Optoelectronics and Optical Communications, University of North Carolina at Charlotte, Charlotte, North Carolina 28223-0001 (United States)

    2016-02-01

    Using a two-dimensional model, we show that the optical images of a sub-wavelength object depend strongly on the excitation of its electromagnetic modes. There exist modes that enable the resolution of the object features smaller than the classical diffraction limit, in particular, due to the destructive interference. We propose to use such modes for super-resolution of resonant structures such as coupled cavities, metal dimers, or bowties. A dielectric microsphere in contact with the object forms its magnified image in a wide range of the virtual image plane positions. It is also suggested that the resonances may significantly affect the resolution quantification in recent experimental studies.

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

    NARCIS (Netherlands)

    Mandrosov, V. I.

    2009-01-01

    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

  13. Full wave model of image formation in optical coherence tomography applicable to general samples.

    Science.gov (United States)

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

    2015-02-09

    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.

  14. In vivo Imaging of Sarcoptes scabiei Infestation Using Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Banzhaf, Christina Alette; Themstrup, Lotte; Ring, Hans Christian

    2013-01-01

    BACKGROUND: Sarcoptes scabiei can be visualized with different imaging tools. Optical coherence tomography (OCT) may have the potential to describe the changes in skin morphology due to scabies infestation and visualize the parasite. METHODS: Five patients from the Departments of Dermatology......, this technology could potentially allow rapid, non-invasive, in vivo diagnosis and analysis of infestations....

  15. Coherent imaging of a pure phase object with classical incoherent light

    DEFF Research Database (Denmark)

    Bache, Morten; Magatti, D.; Gatti, A.

    2007-01-01

    A ghost imaging scheme is used to observe the diffraction pattern of a pure phase object . It is observed that when increasing the spatial coherence the diffraction pattern disappeared from the cross-correlation, while it appeared in the autocorrelation. The cross-correlation contains information...

  16. Imaging of basal cell carcinoma by high-definition optical coherence tomography

    DEFF Research Database (Denmark)

    Boone, M A L M; Norrenberg, S; Jemec, G B E

    2012-01-01

    With the continued development of noninvasive therapies for basal cell carcinoma (BCC) such as photodynamic therapy and immune therapies, noninvasive diagnosis and monitoring become increasingly relevant. High-definition optical coherence tomography (HD-OCT) is a high-resolution imaging tool...

  17. Low-voltage coherent electron imaging based on a single-atom electron

    CERN Document Server

    Chang, Wei-Tse; Hsu, Wei-Hao; Chang, Mu-Tung; Chen, Yi-Sheng; Hwu, En-Te; Hwang, Ing-Shouh

    2015-01-01

    It has been a general trend to develop low-voltage electron microscopes due to their high imaging contrast of the sample and low radiation damage. Atom-resolved transmission electron microscopes with voltages as low as 15-40 kV have been demonstrated. However, achieving atomic resolution at voltages lower than 10 kV is extremely difficult. An alternative approach is coherent imaging or phase retrieval imaging, which requires a sufficiently coherent source and an adequately small detection area on the sample as well as the detection of high-angle diffracted patterns with a sufficient resolution. In this work, we propose several transmission-type schemes to achieve coherent imaging of thin materials (less than 5 nm thick) with atomic resolution at voltages lower than 10 kV. Experimental schemes of both lens-less and lens-containing designs are presented and the advantages and challenges of these schemes are discussed. Preliminary results based on a highly coherent single-atom electron source are presented. The ...

  18. Aerial image simulation for partial coherent system with programming development in MATLAB

    Science.gov (United States)

    Hasan, Md. Nazmul; Rahman, Md. Momtazur; Udoy, Ariful Banna

    2014-10-01

    Aerial image can be calculated by either Abbe's method or sum of coherent system decomposition (SOCS) method for partial coherent system. This paper introduces a programming with Matlab code that changes the analytical representation of Abbe's method to the matrix form, which has advantages for both Abbe's method and SOCS since matrix calculation is easier than double integration over object plane or pupil plane. First a singular matrix P is derived from a pupil function and effective light source in the spatial frequency domain. By applying Singular Value Decomposition (SVD) to the matrix P, eigenvalues and eigenfunctions are obtained. The aerial image can then be computed by the eigenvalues and eigenfunctions without calculation of Transmission Cross Coefficient (TCC). The aerial final image is almost identical as an original cross mask and the intensity distribution on image plane shows that it is almost uniform across the linewidth of the mask.

  19. Resolution enhancement in coherent x-ray diffraction imaging by overcoming instrumental noise.

    Science.gov (United States)

    Kim, Chan; Kim, Yoonhee; Song, Changyong; Kim, Sang Soo; Kim, Sunam; Kang, Hyon Chol; Hwu, Yeukuang; Tsuei, Ku-Ding; Liang, Keng San; Noh, Do Young

    2014-11-17

    We report that reference objects, strong scatterers neighboring weak phase objects, enhance the phase retrieval and spatial resolution in coherent x-ray diffraction imaging (CDI). A CDI experiment with Au nano-particles exhibited that the reference objects amplified the signal-to-noise ratio in the diffraction intensity at large diffraction angles, which significantly enhanced the image resolution. The interference between the diffracted x-ray from reference objects and a specimen also improved the retrieval of the phase of the diffraction signal. The enhancement was applied to image NiO nano-particles and a mitochondrion and confirmed in a simulation with a bacteria phantom. We expect that the proposed method will be of great help in imaging weakly scattering soft matters using coherent x-ray sources including x-ray free electron lasers.

  20. An introduction to medical imaging with coherent terahertz frequency radiation.

    Science.gov (United States)

    Fitzgerald, A J; Berry, E; Zinovev, N N; Walker, G C; Smith, M A; Chamberlain, J M

    2002-04-07

    Methods have recently been developed that make use of electromagnetic radiation at terahertz (THz) frequencies, the region of the spectrum between millimetre wavelengths and the infrared, for imaging purposes. Radiation at these wavelengths is non-ionizing and subject to far less Rayleigh scatter than visible or infrared wavelengths, making it suitable for medical applications. This paper introduces THz pulsed imaging and discusses its potential for in vivo medical applications in comparison with existing modalities.

  1. Advancements in X-ray waveguides and their applications in coherent diffraction imaging

    Energy Technology Data Exchange (ETDEWEB)

    Pelliccia, D. [Institut fuer Synchrotronstrahlung-ANKA Forschungszentrum Karlsruhe Herman-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany)], E-mail: daniele.pelliccia@iss.fzk.de; Bukreeva, I. [Istituto di Fotonica e Nanotecnologie-CNR, Via Cineto Romano 42, 00156 Roma (Italy); Giannini, C.; De Caro, L. [Istituto di Cristallografia-CNR, Via Amendola 122/O, 70126 Bari (Italy); Cedola, A.; Scarinci, F.; Lagomarsino, S. [Istituto di Fotonica e Nanotecnologie-CNR, Via Cineto Romano 42, 00156 Roma (Italy)

    2009-10-15

    X-ray planar waveguides are currently used tools, in synchrotron radiation facilities, to produce a coherent beam with typical dimensions in the range of tens or hundreds of nanometers. The properties of waveguided beams such as divergence and coherence turns out to be very interesting for several applications both in synchrotron and in laboratory sources. These features will be reviewed in the present paper for different coupling methods of the radiation field with the waveguide channel. Details of fabrication procedures and experimental results concerning front coupling waveguide are reported. The waveguide properties can be estimated from the far-field diffracted beam by a Fourier analysis giving the autocorrelation function of the exit field. Due to the high degree of coherence of the exiting beam, X-ray waveguides can be successfully exploited in coherent diffraction imaging experiments. We review results concerning Fresnel coherent diffraction imaging experiments with hard X-rays, using planar waveguides as optical elements in one and two dimensions.

  2. Coherent anti-stokes Raman scattering microscopy: chemical imaging for biology and medicine.

    Science.gov (United States)

    Evans, Conor L; Xie, X Sunney

    2008-01-01

    Coherent anti-Stokes Raman scattering (CARS) microscopy is a label-free imaging technique that is capable of real-time, nonperturbative examination of living cells and organisms based on molecular vibrational spectroscopy. Recent advances in detection schemes, understanding of contrast mechanisms, and developments of laser sources have enabled superb sensitivity and high time resolution. Emerging applications, such as metabolite and drug imaging and tumor identification, raise many exciting new possibilities for biology and medicine.

  3. Feasibility and methodology of optical coherence tomography imaging of human intracranial aneurysms: ex vivo pilot study

    Science.gov (United States)

    Vuong, Barry; Sun, Cuiru; Khiel, Tim-Rasmus; Gardecki, Joseph A.; Standish, Beau A.; da Costa, Leodante; de Morais, Josaphat; Tearney, Guillermo J.; Yang, Victor X. D.

    2012-02-01

    Rupture of intracranial aneurysm is a common cause of subarachnoid hemorrhage. An aneurysm may undergo microscopic morphological changes or remodeling of the vessel wall prior to rupture, which could potentially be imaged. In this study we present methods of tissue sample preparation of intracranial aneurysms and correlation between optical coherence tomography imaging and routine histology. OCT has a potential future in the assessment of microscopic features of aneurysms, which may correlate to the risk of rupture.

  4. Automatic airway wall segmentation and thickness measurement for long-range optical coherence tomography images.

    Science.gov (United States)

    Qi, Li; Huang, Shenghai; Heidari, Andrew E; Dai, Cuixia; Zhu, Jiang; Zhang, Xuping; Chen, Zhongping

    2015-12-28

    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.

  5. Optical coherence tomography imaging in asymptomatic patients with carotid artery stenosis

    Energy Technology Data Exchange (ETDEWEB)

    Cilingiroglu, Mehmet, E-mail: Mcilingiroglu@yahoo.com [University of Pittsburgh Heart and Vascular Institute, Pittsburgh, PA (United States); Hakeem, Abdul [William Beaumont Hospital, Royal Oak, MI (United States); Feldman, Marc [University of Texas Health Sciences Center at San Antonio, San Antonio, TX (United States); Wholey, Mark [University of Pittsburgh Heart and Vascular Institute, Pittsburgh, PA (United States)

    2013-01-15

    Assessment and treatment plan for asymptomatic patients with carotid stenosis are based on angiography at the present time. However, angiography or other imaging modalities are limited with their resolution to detect high-risk plaque features. Intravascular optical coherence tomography (IVOCT) recently emerged as a novel imaging modality with a unique resolution to identify vulnerable plaque characteristics. We report use of IVOCT in two separate asymptomatic patients with carotid stenosis with two different plaque types.

  6. Time-resolved coherent X-ray diffraction imaging of surface acoustic waves.

    Science.gov (United States)

    Nicolas, Jan-David; Reusch, Tobias; Osterhoff, Markus; Sprung, Michael; Schülein, Florian J R; Krenner, Hubert J; Wixforth, Achim; Salditt, Tim

    2014-10-01

    Time-resolved coherent X-ray diffraction experiments of standing surface acoustic waves, illuminated under grazing incidence by a nanofocused synchrotron beam, are reported. The data have been recorded in stroboscopic mode at controlled and varied phase between the acoustic frequency generator and the synchrotron bunch train. At each time delay (phase angle), the coherent far-field diffraction pattern in the small-angle regime is inverted by an iterative algorithm to yield the local instantaneous surface height profile along the optical axis. The results show that periodic nanoscale dynamics can be imaged at high temporal resolution in the range of 50 ps (pulse length).

  7. Optical coherence tomography imaging of chorioretinal folds associated with hypotony maculopathy following pars plana vitrectomy

    Directory of Open Access Journals (Sweden)

    Williams Jr BK

    2015-09-01

    Full Text Available Basil K Williams Jr, Jonathan S Chang, Harry W Flynn Jr Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA Abstract: Chorioretinal folds may occur as a consequence of hypotony and can be a cause of vision loss when associated with macular involvement. In this report, the spectral domain ocular coherence tomography imaging of three patients with chorioretinal folds before and after management are presented. The cases had unique presentations and each underwent different management approaches, but the results included improved visual acuities and lessened chorioretinal folds. Keywords: hypotony, chorioretinal folds, ocular coherence tomography

  8. High-definition optical coherence tomography imaging of melanocytic lesions

    DEFF Research Database (Denmark)

    Boone, Marc A L M; Norrenberg, Sarah; Jemec, Gregor B E

    2014-01-01

    were imaged. Identification of architectural patterns in cross-sectional mode and cytologic features of pigmented cells in the epidermis, dermo-epidermal junction, papillary dermis, and superficial reticular dermis in the en face mode was possible by HD-OCT. HD-OCT provides morphological imaging...... with sufficient resolution and penetration depth to discriminate architectural patterns and cytologic features of pigmented cells in epidermis and dermis. The method appears to offer the possibility of additional three-dimensional structural information complementary to that of RCM, albeit at a slightly lower...

  9. Human skin image analysis using coherent focused beam scattering

    Science.gov (United States)

    Zimnyakov, Dmitry A.; Tuchin, Valery V.; Utz, Sergei R.; Mishin, Alexey A.

    1995-02-01

    The analysis of statistical and correlation properties of speckle patterns formed during different skin tissue scanning by the sharply focused probing laser beam has been carried out. The influences of the biotissues' structural features on the speckle patterns formation under Gaussian beam illumination have been investigated. The relationships between the structural characteristics of the sample under study, Rayleigh range of the probing beam and normalized statistical moments of the speckle intensity (contrast and asymmetry coefficient) are discussed for the different scatterer models. A phenomenological model of speckle pattern formation for the large-scale scatterers allows us to explain the dependence of speckle contrast and the coefficient of asymmetry on the generalized structure parameters and illumination conditions for the samples under study. The experimental investigations of the human skin structure features have been carried out using two types of the tissue samples by means of coherent scanning microscopy (CSM). Firstly, D-SQUAME discs (CuDerm Corporation, Texas, USA) have been used for the evaluation of skin dryness level. Secondly, the samples under study were the thin layers of normal and psoriatic epidermis (skin strippings). The dependencies of contrast and coefficient of asymmetry on the beam defocusing parameter and 2D correlation functions of speckle pattern intensity have been analyzed for different zones on the biotissue's surface. Particularly, promising results in skin dryness studies (using D-SQUAME discs) have been obtained. Our results and conventional 5-pattern kit scale are in good agreement. So, the presented method is accurate and objective and may be useful in novel cosmetic research and development.

  10. Influence of partial coherence on analyzer-based imaging with asymmetric Bragg reflection.

    Science.gov (United States)

    Modregger, Peter; Lübbert, Daniel; Schäfer, Peter; Richter, Jane; Köhler, Rolf; Baumbach, Tilo

    2009-07-06

    Image magnification via twofold asymmetric Bragg reflection (a setup called the "Bragg Magnifier") is a recently established technique allowing to achieve both sub-micrometer spatial resolution and phase contrast in X-ray imaging. The present article extends a previously developed theoretical formalism to account for partially coherent illumination. At a typical synchrotron setup polychromatic illumination is identified as the main influence of partial coherence and the implications on imaging characteristics are analyzed by numerical simulations. We show that contrast decreases by about 50% when compared to the monochromatic case, while sub-micrometer spatial resolution is preserved. The theoretical formalism is experimentally verified by correctly describing the dispersive interaction of the two orthogonal magnifier crystals, an effect that has to be taken into account for precise data evaluation.

  11. Coherent x-ray diffraction imaging of paint pigmentparticles by scanning a phase plate modulator

    Energy Technology Data Exchange (ETDEWEB)

    Chu Y. S.; Chen B.; Zhang F.; Berenguer F.; Bean R.; Kewish C.; Vila-Comamala J.; Rodenburg J.; Robinson I.

    2011-10-19

    We have implemented a coherent x-ray diffraction imaging technique that scans a phase plate to modulate wave-fronts of the x-ray beam transmitted by samples. The method was applied to measure a decorative alkyd paint containing iron oxide red pigment particles. By employing an iterative algorithm for wave-front modulation phase retrieval, we obtained an image of the paint sample that shows the distribution of the pigment particles and is consistent with the result obtained from a transmission x-ray microscope. The technique has been experimentally proven to be a feasible coherent x-ray imaging method with about 120 nm spatial resolution and was shown to work well with industrially relevant specimens.

  12. Coherent diffractive imaging of single helium nanodroplets with a high harmonic generation source

    CERN Document Server

    Rupp, Daniela; Langbehn, Bruno; Sauppe, Mario; Zimmermann, Julian; Ovcharenko, Yevheniy; Möller, Thomas; Frassetto, Fabio; Poletto, Luca; Trabattoni, Andrea; Calegari, Francesca; Nisoli, Mauro; Sander, Katharina; Peltz, Christian; Vrakking, Marc J J; Fennel, Thomas; Rouzée, Arnaud

    2016-01-01

    Coherent diffractive imaging of individual free nanoparticles has opened novel routes for the in-situ analysis of their transient structural, optical, and electronic properties. So far, single-particle diffraction was assumed to be feasible only at extreme ultraviolet (XUV) and X-ray free-electron lasers, restricting this research field to large-scale facilities. Here we demonstrate single-shot imaging of isolated helium nanodroplets using XUV pulses from a femtosecond-laser driven high harmonic source. We obtain bright scattering patterns that provide access to the nanostructure's optical parameters. Moreover, the wide-angle scattering data enable us to uniquely identify hitherto unresolved prolate shapes of superfluid helium droplets. Our results mark the advent of single-shot gas-phase nanoscopy with lab-based short-wavelength pulses and pave the way to ultrafast coherent diffractive imaging with phase-controlled multicolor fields and attosecond pulses.

  13. Coherence Imaging Measurements of Impurity Flow in the Compact Toroidal Hybrid Experiment

    Science.gov (United States)

    Ennis, D. A.; Hartwell, G. J.; Johnson, C. A.; Maurer, D. A.; Allen, S. L.; Meyer, W. H.; Samuell, C. M.

    2016-10-01

    Measurements of impurity ion emissivity and velocity in the Compact Toroidal Hybrid (CTH) experiment are achieved with a new optical coherence imaging diagnostic. The Coherence Imaging Spectroscopy (CIS) technique measures the spectral coherence of an emission line with an imaging interferometer of fixed delay. CIS has a number of advantages when compared to dispersive Doppler spectroscopy, including higher throughput and the capability to provide 2D spectral images, making it ideal for investigating the non-axisymmetric geometry of CTH plasmas. Furthermore, detailed measurements of the ion flow structure provided by CIS combined with predictive computational models could also provide spatially resolved images of complex flow structures, such as those associated with an island divertor. First CIS measurements of CTH plasmas reveal strong signals for C III (465 nm), He II (468 nm) and C II (513 nm) emission. Preliminary analysis of C III interferograms indicate a net toroidal flow on the order of 10 km/s during the time of peak current. Bench tests using Zn and Cd light sources reveal that the temperature of the instrument must be actively controlled to within 0.01°C to limit phase drift of the interferometer resulting in artificially measured flow. Results from this diagnostic will aid in characterizing the ion flow in planned island divertor and MHD mode-locking experiments. Work supported by USDoE Grant DE-FG02-00ER54610.

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

    Science.gov (United States)

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

    2016-12-01

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

  15. Phase resolved and coherence gated en face reflection imaging of multilayered embryonal carcinoma cells

    Science.gov (United States)

    Yamauchi, Toyohiko; Fukami, Tadashi; Iwai, Hidenao; Yamashita, Yutaka

    2012-03-01

    Embryonal carcinoma (EC) cells, which are cell lines derived from teratocarcinomas, have characteristics in common with stem cells and differentiate into many kinds of functional cells. Similar to embryonic stem (ES) cells, undifferentiated EC cells form multi-layered spheroids. In order to visualize the three-dimensional structure of multilayered EC cells without labeling, we employed full-field interference microscopy with the aid of a low-coherence quantitative phase microscope, which is a reflection-type interference microscope employing the digital holographic technique with a low-coherent light source. Owing to the low-coherency of the light-source (halogen lamp), only the light reflected from reflective surface at a specific sectioning height generates an interference image on the CCD camera. P19CL6 EC cells, derived from mouse teratocarcinomas, formed spheroids that are about 50 to 200 micrometers in diameter. Since the height of each cell is around 10 micrometers, it is assumed that each spheroid has 5 to 20 cell layers. The P19CL6 spheroids were imaged in an upright configuration and the horizontally sectioned reflection images of the sample were obtained by sequentially and vertically scanning the zero-path-length height. Our results show the threedimensional structure of the spheroids, in which plasma and nuclear membranes were distinguishably imaged. The results imply that our technique is further capable of imaging induced pluripotent stem (iPS) cells for the assessment of cell properties including their pluripotency.

  16. Spiking cortical model-based nonlocal means method for speckle reduction in optical coherence tomography images

    Science.gov (United States)

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

    2014-06-01

    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.

  17. How histological features of basal cell carcinomas influence image quality in optical coherence tomography

    DEFF Research Database (Denmark)

    Mogensen, Mette; Nürnberg, Birgit M.; Thrane, Lars

    2011-01-01

    Optical coherence tomography (OCT) has the potential to diagnose and measure the depth of nonmelanoma skin cancer (NMSC) in skin, but some lesions appear blurred in OCT images. The aim of this study is to identify histological characteristics of basal cell carcinomas (BCC) that correlate with good...... quality OCT images of the same lesions. A total of 34 patients with BCC were OCT scanned. The influence of histology parameters (e.g. inflammation, sun damage of skin, carcinoma cell size) on OCT image quality was studied by comparing 15 BCC lesions easily identified compared to 19 BCC lesions...... that produced only blurred in OCT images. Inflammation was more pronounced in blurred OCT images, whereas solar elastosis dominated in easily identified lesions. Hyperkeratosis did not impair imaging significantly. OCT image quality of BCC may depend on specific histology parameters....

  18. Spiking cortical model-based nonlocal means method for speckle reduction in optical coherence tomography images.

    Science.gov (United States)

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

    2014-06-01

    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.

  19. Resonant Doppler imaging with Fourier domain optical coherence tomography

    Science.gov (United States)

    Leitgeb, Rainer A.; Szklumowska, Anna; Pircher, Michael; Gotzinger, Erich; Fercher, Adolf F.

    2005-04-01

    Fourier Domain Optical Coherene Tomography (FD OCT) is a high speed imaging modality with increased sensitivity as compared to standard time domain (TD) OCT. The higher sensitivity is especially important, if strongly scattering tissue such as blood is investigated. Recently it could be shown that retinal blood flow can be assessed in-vivo by high speed FD OCT. However the detection bandwidth of color Doppler (CD) FDOCT is strongly limited due to blurring of the detected interference fringes during exposure. This leads to a loss of sensitivity for detection of fast changes in tissue. Using a moving mirror as a reference one can effectively increase the detection bandwidth for CD FDOCT and perform perfusion sectioning. The modality is called resonant CD FDOCT imaging. The principle of the method is presented and experimentally verified.

  20. Imaging of collagen deposition disorders using optical coherence tomography

    DEFF Research Database (Denmark)

    Ring, H C; Mogensen, M; Hussain, A A

    2015-01-01

    BACKGROUND: Collagen deposition disorders such as hypertrophic scars, keloids and scleroderma can be associated with significant stigma and embarrassment. These disorders often constitute considerable impairment to quality of life, with treatment posing to be a substantial challenge. Optical...... lesion type. Hypertrophic scars displayed an increased vascularity and signal-rich bands correlating to excessive collagen deposition. Keloids depicted a disarray of hyper-reflective areas primarily located in the upper dermis. Additionally, the dermis displayed a heterogeneous morphology without...... indications of any vascular supply or lymphatic network. In contrast to keloids, scleroderma displayed a more cohesive backscattering indicating a difference in density of collagen or other dermal structures. OCT images demonstrated no significant differences between mean density measurements in OCT images...

  1. Imaging coherent sources of tremor related EEG activity in patients with Parkinson's disease.

    Science.gov (United States)

    Muthuraman, M; Raethjen, J; Hellriegel, H; Deuschl, G; Heute, U

    2008-01-01

    The cortical sources of both the basic and first 'harmonic' frequency of Parkinsonian tremor are addressed in this paper. The power and coherence was estimated using the multitaper method for EEG and EMG data from 6 Parkinsonian patients with a classical rest tremor. The Dynamic Imaging of Coherent Sources (DICS) was used to find the coherent sources in the brain. Before hand this method was validated for the application to the EEG by showing in 3 normal subjects that rhythmic stimuli (1-5Hz) to the median nerve leads to almost identical coherent sources for the basic and first harmonic frequency in the contralateral sensorimotor cortex which is the biologically plausible result. In all the Parkinson patients the corticomuscular coherence was also present in the basic and the first harmonic frequency of the tremor. However, the source for the basic frequency was close to the frontal midline and the first harmonic frequency was in the region of premotor and sensory motor cortex on the contralateral side for all the patients. Thus the generation of these two oscillations involves different cortical areas and possibly follows different pathways to the periphery.

  2. Aberrations in shift-invariant linear optical imaging systems using partially coherent fields

    CERN Document Server

    Beltran, Mario A; Paganin, David M

    2014-01-01

    Here the role and influence of aberrations in optical imaging systems employing partially coherent complex scalar fields is studied. Imaging systems require aberrations to yield contrast in the output image. For linear shift-invariant optical systems, we develop an expression for the output cross-spectral density under the space-frequency formulation of statistically stationary partially coherentfields. We also develop expressions for the output cross{spectral density and associated spectral density for weak-phase, weak-phase-amplitude, and single-material objects in one transverse spatial dimension.

  3. High precision, medium flux rate CZT spectroscopy for coherent scatter imaging

    Science.gov (United States)

    Greenberg, Joel A.; Hassan, Mehadi; Brady, David J.; Iniewski, Kris

    2016-05-01

    CZT detectors are primary candidates for many next-generation X-ray imaging systems. These detectors are typically operated in either a high precision, low flux spectroscopy mode or a low precision, high flux photon counting mode. We demonstrate a new detector configuration that enables operation in a high precision, medium flux spectroscopy mode, which opens the potential for a variety of new applications in medical imaging, non-destructive testing and baggage scanning. In particular, we describe the requirements of a coded aperture coherent scattering X-ray system that can perform fast imaging with accurate material discrimination.

  4. Real-time dispersion-compensated image reconstruction for compressive sensing spectral domain optical coherence tomography.

    Science.gov (United States)

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

    2014-09-01

    In this work, we propose a novel dispersion compensation method that enables real-time compressive sensing (CS) spectral domain optical coherence tomography (SD OCT) image reconstruction. We show that dispersion compensation can be incorporated into CS SD OCT by multiplying the dispersion-correcting terms by the undersampled spectral data before CS reconstruction. High-quality SD OCT imaging with dispersion compensation was demonstrated at a speed in excess of 70 frames per s using 40% of the spectral measurements required by the well-known Shannon/Nyquist theory. The data processing and image display were performed on a conventional workstation having three graphics processing units.

  5. Dual Modality Photothermal Optical Coherence Tomography and Magnetic Resonance Imaging of Carbon Nanotubes

    OpenAIRE

    Tucker – Schwartz, Jason M.; Hong, Tu; Colvin, Daniel C.; Xu, Yaqiong; Skala, Melissa C.

    2012-01-01

    We demonstrate polyethylene glycol coated single-walled carbon nanotubes (CNTs) as contrast agents for both photothermal optical coherence tomography (OCT) and magnetic resonance imaging. Photothermal OCT was accomplished with a spectral domain OCT system with an amplitude modulated 750 nm pump beam using 10 mW of power, and T2 MR imaging was achieved with a 4.7 T animal system. Photothermal OCT and T2 MR imaging achieved sensitivities of nM concentrations to CNTs dispersed in amine terminate...

  6. An elegant technique for ex vivo imaging in experimental research—Optical coherence tomography (OCT)

    DEFF Research Database (Denmark)

    Tschernig, T.; Thrane, Lars; Jørgensen, Thomas Martini

    2013-01-01

    Optical coherence tomography (OCT) is an elegant technology for imaging of tissues and organs and has been established for clinical use for around a decade. Thus, it is used in vivo but can also serve as a valuable ex vivo imaging tool in experimental research. Here, a brief overview is given...... with a focus on an ex vivo application of OCT. Image and video examples of freshly obtained murine lungs are included. The main advantage of OCT for ex vivo analysis is the non-contact, non-invasive, and non-destructive fast acquisition of a three-dimensional data set with micrometer-resolution....

  7. High sensitivity contrast enhanced optical coherence tomography for functional in vivo imaging

    Science.gov (United States)

    Liba, Orly; SoRelle, Elliott D.; Sen, Debasish; de la Zerda, Adam

    2017-02-01

    In this study, we developed and applied highly-scattering large gold nanorods (LGNRs) and custom spectral detection algorithms for high sensitivity contrast-enhanced optical coherence tomography (OCT). We were able to detect LGNRs at a concentration as low as 50 pM in blood. We used this approach for noninvasive 3D imaging of blood vessels deep in solid tumors in living mice. Additionally, we demonstrated multiplexed imaging of spectrally-distinct LGNRs that enabled observations of functional drainage in lymphatic networks. This method, which we call MOZART, provides a platform for molecular imaging and characterization of tissue noninvasively at cellular resolution.

  8. A signal separation technique for sub-cellular imaging using dynamic optical coherence tomography

    CERN Document Server

    Ammari, Habib; Shi, Cong

    2016-01-01

    This paper aims at imaging the dynamics of metabolic activity of cells. Using dynamic optical coherence tomography, we introduce a new multi-particle dynamical model to simulate the movements of the collagen and the cell metabolic activity and develop an efficient signal separation technique for sub-cellular imaging. We perform a singular-value decomposition of the dynamic optical images to isolate the intensity of the metabolic activity. We prove that the largest eigenvalue of the associated Casorati matrix corresponds to the collagen. We present several numerical simulations to illustrate and validate our approach.

  9. Diffractive Imaging of Coherent Nuclear Motion in Isolated Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jie; Guehr, Markus; Shen, Xiaozhe; Li, Renkai; Vecchione, Theodore; Coffee, Ryan; Corbett, Jeff; Fry, Alan; Hartmann, Nick; Hast, Carsten; Hegazy, Kareem; Jobe, Keith; Makasyuk, Igor; Robinson, Joseph; Robinson, Matthew S.; Vetter, Sharon; Weathersby, Stephen; Yoneda, Charles; Wang, Xijie; Centurion, Martin

    2016-10-03

    Observing the motion of the nuclear wave packets during a molecular reaction, in both space and time, is crucial for understanding and controlling the outcome of photoinduced chemical reactions. We have imaged the motion of a vibrational wave packet in isolated iodine molecules using ultrafast electron diffraction with relativistic electrons. The time-varying interatomic distance was measured with a precision 0.07 Å and temporal resolution of 230 fs full width at half maximum. The method is not only sensitive to the position but also the shape of the nuclear wave packet.

  10. Aborted choroidal coloboma: fundus imaging and optical coherence tomography.

    Science.gov (United States)

    Takkar, Brijesh; Venkatesh, Pradeep; Khokhar, Sudarshan; Gagrani, Meghal

    2017-08-07

    Choroidal coloboma is characterised by poor embryonic development of chorioretinal structures and is of different types. We present a case of choroidal coloboma where the retinal pigment epithelium was present, clinically and on imaging, but rest of the structures were poorly formed. This observation suggests that in some cases, fusion of the fetal cleft may occur aberrantly, resulting in an aborted choroidal coloboma. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  11. Diffractive Imaging of Coherent Nuclear Motion in Isolated Molecules

    CERN Document Server

    Yang, Jie; Shen, Xiaozhe; Li, Renkai; Vecchione, Theodore; Coffee, Ryan; Corbett, Jeff; Fry, Alan; Hartmann, Nick; Hast, Carsten; Hegazy, Kareem; Jobe, Keith; Makasyuk, Igor; Robinson, Joseph; Robinson, Matthew S; Vetter, Sharon; Weathersby, Stephen; Yoneda, Charles; Wang, Xijie; Centurion, Martin

    2016-01-01

    Observing the motion of the nuclear wavepackets during a molecular reaction, in both space and time, is crucial for understanding and controlling the outcome of photoinduced chemical reactions. We have imaged the motion of a vibrational wavepacket in isolated iodine molecules using ultrafast electron diffraction with relativistic electrons. The time-varying interatomic distance was measured with a precision 0.07 {\\AA} and temporal resolution of 230 fs full-width at half-maximum (FWHM). The method is not only sensitive to the position but also the shape of the nuclear wavepacket.

  12. Information surfing with the JHU/APL coherent imager

    Science.gov (United States)

    Ratto, Christopher R.; Shipley, Kara R.; Beagley, Nathaniel; Wolfe, Kevin C.

    2015-05-01

    The ability to perform remote forensics in situ is an important application of autonomous undersea vehicles (AUVs). Forensics objectives may include remediation of mines and/or unexploded ordnance, as well as monitoring of seafloor infrastructure. At JHU/APL, digital holography is being explored for the potential application to underwater imaging and integration with an AUV. In previous work, a feature-based approach was developed for processing the holographic imagery and performing object recognition. In this work, the results of the image processing method were incorporated into a Bayesian framework for autonomous path planning referred to as information surfing. The framework was derived assuming that the location of the object of interest is known a priori, but the type of object and its pose are unknown. The path-planning algorithm adaptively modifies the trajectory of the sensing platform based on historical performance of object and pose classification. The algorithm is called information surfing because the direction of motion is governed by the local information gradient. Simulation experiments were carried out using holographic imagery collected from submerged objects. The autonomous sensing algorithm was compared to a deterministic sensing CONOPS, and demonstrated improved accuracy and faster convergence in several cases.

  13. First Results from a Coherence Imaging Diagnostic for the Compact Toroidal Hybrid

    Science.gov (United States)

    Ennis, D. A.; Hartwell, G. J.; Johnson, C. A.; Maurer, D. A.; Allen, S. L.

    2015-11-01

    An optical coherence imaging diagnostic is being commissioned for time-resolved measurements (~ 10 ms) of ion emissivity, velocity, and temperature in the Compact Toroidal Hybrid (CTH) experiment. The Coherence Imaging (CI) technique measures the spectral coherence of an emission line with an imaging interferometer of fixed delay. CI has a number of advantages when compared to dispersive Doppler spectroscopy, including higher throughput and the capability to provide 2D spectral images, making it advantageous for investigating the non-axisymmetric geometry of CTH plasmas. A spectral survey of the visible and ultraviolet emission for a range of CTH discharges has identified helium and carbon impurity lines that will be utilized for CI measurements in CTH. First CI measurements of He II (468.6 nm) emission from CTH plasmas will be presented along with interferograms from a calibration light source and details of the instrument design. Results from this diagnostic will aid in characterizing the equilibrium ion parameters in both the edge and core of CTH plasmas for planned island divertor and MHD mode-locking experiments. Work supported by USDoE grant DE-FG02-00ER54610.

  14. Image-space texture-based output-coherent surface flow visualization.

    Science.gov (United States)

    Huang, Jin; Pan, Zherong; Chen, Guoning; Chen, Wei; Bao, Hujun

    2013-09-01

    Image-space line integral convolution (LIC) is a popular scheme for visualizing surface vector fields due to its simplicity and high efficiency. To avoid inconsistencies or color blur during the user interactions, existing approaches employ surface parameterization or 3D volume texture schemes. However, they often require expensive computation or memory cost, and cannot achieve consistent results in terms of both the granularity and color distribution on different scales. This paper introduces a novel image-space surface flow visualization approach that preserves the coherence during user interactions. To make the noise texture under different viewpoints coherent, we propose to precompute a sequence of mipmap noise textures in a coarse-to-fine manner for consistent transition, and map the textures onto each triangle with randomly assigned and constant texture coordinates. Further, a standard image-space LIC is performed to generate the flow texture. The proposed approach is simple and GPU-friendly, and can be easily combined with various texture-based flow visualization techniques. By leveraging viewpoint-dependent backward tracing and mipmap noise phase, our method can be incorporated with the image-based flow visualization (IBFV) technique for coherent visualization of unsteady flows. We demonstrate consistent and highly efficient flow visualization on a variety of data sets.

  15. Facing the phase problem in Coherent Diffractive Imaging via Memetic Algorithms

    Science.gov (United States)

    Colombo, Alessandro; Galli, Davide Emilio; de Caro, Liberato; Scattarella, Francesco; Carlino, Elvio

    2017-02-01

    Coherent Diffractive Imaging is a lensless technique that allows imaging of matter at a spatial resolution not limited by lens aberrations. This technique exploits the measured diffraction pattern of a coherent beam scattered by periodic and non–periodic objects to retrieve spatial information. The diffracted intensity, for weak–scattering objects, is proportional to the modulus of the Fourier Transform of the object scattering function. Any phase information, needed to retrieve its scattering function, has to be retrieved by means of suitable algorithms. Here we present a new approach, based on a memetic algorithm, i.e. a hybrid genetic algorithm, to face the phase problem, which exploits the synergy of deterministic and stochastic optimization methods. The new approach has been tested on simulated data and applied to the phasing of transmission electron microscopy coherent electron diffraction data of a SrTiO3 sample. We have been able to quantitatively retrieve the projected atomic potential, and also image the oxygen columns, which are not directly visible in the relevant high-resolution transmission electron microscopy images. Our approach proves to be a new powerful tool for the study of matter at atomic resolution and opens new perspectives in those applications in which effective phase retrieval is necessary.

  16. High-dynamic-range coherent diffractive imaging: ptychography using the mixed-mode pixel array detector

    Energy Technology Data Exchange (ETDEWEB)

    Giewekemeyer, Klaus, E-mail: klaus.giewekemeyer@xfel.eu [European XFEL GmbH, Hamburg (Germany); Philipp, Hugh T. [Cornell University, Ithaca, NY (United States); Wilke, Robin N. [Georg-August-Universität Göttingen, Göttingen (Germany); Aquila, Andrew [European XFEL GmbH, Hamburg (Germany); Osterhoff, Markus [Georg-August-Universität Göttingen, Göttingen (Germany); Tate, Mark W.; Shanks, Katherine S. [Cornell University, Ithaca, NY (United States); Zozulya, Alexey V. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Salditt, Tim [Georg-August-Universität Göttingen, Göttingen (Germany); Gruner, Sol M. [Cornell University, Ithaca, NY (United States); Cornell University, Ithaca, NY (United States); Kavli Institute of Cornell for Nanoscience, Ithaca, NY (United States); Mancuso, Adrian P. [European XFEL GmbH, Hamburg (Germany)

    2014-08-07

    The advantages of a novel wide dynamic range hard X-ray detector are demonstrated for (ptychographic) coherent X-ray diffractive imaging. Coherent (X-ray) diffractive imaging (CDI) is an increasingly popular form of X-ray microscopy, mainly due to its potential to produce high-resolution images and the lack of an objective lens between the sample and its corresponding imaging detector. One challenge, however, is that very high dynamic range diffraction data must be collected to produce both quantitative and high-resolution images. In this work, hard X-ray ptychographic coherent diffractive imaging has been performed at the P10 beamline of the PETRA III synchrotron to demonstrate the potential of a very wide dynamic range imaging X-ray detector (the Mixed-Mode Pixel Array Detector, or MM-PAD). The detector is capable of single photon detection, detecting fluxes exceeding 1 × 10{sup 8} 8-keV photons pixel{sup −1} s{sup −1}, and framing at 1 kHz. A ptychographic reconstruction was performed using a peak focal intensity on the order of 1 × 10{sup 10} photons µm{sup −2} s{sup −1} within an area of approximately 325 nm × 603 nm. This was done without need of a beam stop and with a very modest attenuation, while ‘still’ images of the empty beam far-field intensity were recorded without any attenuation. The treatment of the detector frames and CDI methodology for reconstruction of non-sensitive detector regions, partially also extending the active detector area, are described.

  17. Optical Coherence Tomography: An Emerging Technology for Biomedical Imaging and Optical Biopsy1

    Science.gov (United States)

    Fujimoto, James G; Pitris, Costas; Boppart, Stephen A; Brezinski, Mark E

    2000-01-01

    Abstract Optical coherence tomography (OCT) is an emerging technology for performing high-resolution cross-sectional imaging. OCT is analogous to ultrasound imaging, except that it uses light instead of sound. OCT can provide cross-sectional images of tissue structure on the micron scale in situ and in real time. Using OCT in combination with catheters and endoscopes enables high-resolution intraluminal imaging of organ systems. OCT can function as a type of optical biopsy and is a powerful imaging technology for medical diagnostics because unlike conventional histopathology which requires removal of a tissue specimen and processing for microscopic examination, OCT can provide images of tissue in situ and in real time. OCT can be used where standard excisional biopsy is hazardous or impossible, to reduce sampling errors associated with excisional biopsy, and to guide interventional procedures. In this paper, we review OCT technology and describe its potential biomedical and clinical applications. PMID:10933065

  18. In vivo deep tissue imaging using wavefront shaping optical coherence tomography

    CERN Document Server

    Yu, Hyeonseung; Lee, KyeoReh; Jang, Jaeduck; Lim, Jaeguyn; Jang, Wooyoung; Jeong, Yong; Park, YongKeun

    2015-01-01

    Multiple light scattering in tissue limits the penetration of optical coherence tomography (OCT) imaging. Here, we present in-vivo OCT imaging of a live mouse using wavefront shaping to enhance the penetration depth. A digital micro-mirror device (DMD) was used in a spectral-domain OCT system for complex wavefront shaping of an incident beam which resulted in the optimal delivery of light energy into deep tissue. Ex-vivo imaging of chicken breasts and mouse ear tissues showed enhancements in the strength of the image signals and the penetration depth, and in-vivo imaging of the tail of a live mouse provided a multilayered structure inside the tissue, otherwise invisible in conventional OCT imaging. Signal enhancements by a factor of 3-7 were acquired for various experimental conditions and samples.

  19. Tissue Equivalent Phantom Design for Characterization of a Coherent Scatter X-ray Imaging System

    Science.gov (United States)

    Albanese, Kathryn Elizabeth

    Scatter in medical imaging is typically cast off as image-related noise that detracts from meaningful diagnosis. It is therefore typically rejected or removed from medical images. However, it has been found that every material, including cancerous tissue, has a unique X-ray coherent scatter signature that can be used to identify the material or tissue. Such scatter-based tissue-identification provides the advantage of locating and identifying particular materials over conventional anatomical imaging through X-ray radiography. A coded aperture X-ray coherent scatter spectral imaging system has been developed in our group to classify different tissue types based on their unique scatter signatures. Previous experiments using our prototype have demonstrated that the depth-resolved coherent scatter spectral imaging system (CACSSI) can discriminate healthy and cancerous tissue present in the path of a non-destructive x-ray beam. A key to the successful optimization of CACSSI as a clinical imaging method is to obtain anatomically accurate phantoms of the human body. This thesis describes the development and fabrication of 3D printed anatomical scatter phantoms of the breast and lung. The purpose of this work is to accurately model different breast geometries using a tissue equivalent phantom, and to classify these tissues in a coherent x-ray scatter imaging system. Tissue-equivalent anatomical phantoms were designed to assess the capability of the CACSSI system to classify different types of breast tissue (adipose, fibroglandular, malignant). These phantoms were 3D printed based on DICOM data obtained from CT scans of prone breasts. The phantoms were tested through comparison of measured scatter signatures with those of adipose and fibroglandular tissue from literature. Tumors in the phantom were modeled using a variety of biological tissue including actual surgically excised benign and malignant tissue specimens. Lung based phantoms have also been printed for future

  20. Application of improved homogeneity similarity-based denoising in optical coherence tomography retinal images.

    Science.gov (United States)

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

    2015-06-01

    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.

  1. Exploring coherent phenomena and energy discrimination in X-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, Thomas

    2011-05-04

    Conventional X-ray imaging is based on the generation of photons in materials that are selected for different applications according to their densities, dimensions, and atomic numbers. The photons produced in these targets are commonly detected by measuring the integrated amount of energy released in films or digital imaging systems. This thesis aims at extending these two paradigms. First, it is shown that the use of single-crystalline, i.e. well-ordered targets, can significantly soften photon spectra created by megavoltage electrons when compared to usual targets. The reason for this is an effect called ''coherent bremsstrahlung''. It is shown that this type of radiation bears the potential of increasing the quality of megavoltage images and reducing radiation dose for image guided radiotherapy. Second, new spectroscopic pixel detectors of the Medipix2 family operated with cadmium telluride sensors are characterised and thus potential benefits and difficulties for X-ray imaging are investigated. Besides describing in detail how to calibrate these detectors, emphasis is placed on determining their energy responses, modulation transfer functions, and detective quantum efficiencies. Requirements for photon counting megavoltage imaging are discussed. The detector systems studied are finally used to perform spectral computed tomography and to illustrate the benefits of energy discrimination for coherent scatter imaging. (orig.)

  2. Full-field optical coherence tomography image restoration based on Hilbert transformation

    Science.gov (United States)

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

    2007-02-01

    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.

  3. Optical coherence tomography imaging of the basal ganglia: feasibility and brief review

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, W. O. Contreras; Ângelos, J. S. [Divisão de Neurocirurgia Funcional, Departamento de Neurologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil); Martinez, R. C. R. [Laboratório de Neuromodulação e Dor Experimental, Hospital Sírio-Libanes, São Paulo, SP (Brazil); Takimura, C. K. [Instituto do Coração, Universidade de São Paulo, São Paulo, SP (Brazil); Teixeira, M. J. [Divisão de Neurocirurgia Funcional, Departamento de Neurologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil); Lemos, P. A. Neto [Instituto do Coração, Universidade de São Paulo, São Paulo, SP (Brazil); Fonoff, E. T., E-mail: fonoffet@usp.br [Divisão de Neurocirurgia Funcional, Departamento de Neurologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil)

    2015-09-29

    Optical coherence tomography (OCT) is a promising medical imaging technique that uses light to capture real-time cross-sectional images from biological tissues in micrometer resolution. Commercially available optical coherence tomography systems are employed in diverse applications, including art conservation and diagnostic medicine, notably in cardiology and ophthalmology. Application of this technology in the brain may enable distinction between white matter and gray matter, and obtainment of detailed images from within the encephalon. We present, herein, the in vivo implementation of OCT imaging in the rat brain striatum. For this, two male 60-day-old rats (Rattus norvegicus, Albinus variation, Wistar) were stereotactically implanted with guide cannulas into the striatum to guide a 2.7-French diameter high-definition OCT imaging catheter (Dragonfly™, St. Jude Medical, USA). Obtained images were compared with corresponding histologically stained sections to collect imaging samples. A brief analysis of OCT technology and its current applications is also reported, as well as intra-cerebral OCT feasibility on brain mapping during neurosurgical procedures.

  4. Speckle reduction in optical coherence tomography images based on wave atoms

    Science.gov (United States)

    Du, Yongzhao; Liu, Gangjun; Feng, Guoying; Chen, Zhongping

    2014-01-01

    Abstract. Optical coherence tomography (OCT) is an emerging noninvasive imaging technique, which is based on low-coherence interferometry. OCT images suffer from speckle noise, which reduces image contrast. A shrinkage filter based on wave atoms transform is proposed for speckle reduction in OCT images. Wave atoms transform is a new multiscale geometric analysis tool that offers sparser expansion and better representation for images containing oscillatory patterns and textures than other traditional transforms, such as wavelet and curvelet transforms. Cycle spinning-based technology is introduced to avoid visual artifacts, such as Gibbs-like phenomenon, and to develop a translation invariant wave atoms denoising scheme. The speckle suppression degree in the denoised images is controlled by an adjustable parameter that determines the threshold in the wave atoms domain. The experimental results show that the proposed method can effectively remove the speckle noise and improve the OCT image quality. The signal-to-noise ratio, contrast-to-noise ratio, average equivalent number of looks, and cross-correlation (XCOR) values are obtained, and the results are also compared with the wavelet and curvelet thresholding techniques. PMID:24825507

  5. High-dynamic-range coherent diffractive imaging: ptychography using the mixed-mode pixel array detector

    Science.gov (United States)

    Giewekemeyer, Klaus; Philipp, Hugh T.; Wilke, Robin N.; Aquila, Andrew; Osterhoff, Markus; Tate, Mark W.; Shanks, Katherine S.; Zozulya, Alexey V.; Salditt, Tim; Gruner, Sol M.; Mancuso, Adrian P.

    2014-01-01

    Coherent (X-ray) diffractive imaging (CDI) is an increasingly popular form of X-ray microscopy, mainly due to its potential to produce high-resolution images and the lack of an objective lens between the sample and its corresponding imaging detector. One challenge, however, is that very high dynamic range diffraction data must be collected to produce both quantitative and high-resolution images. In this work, hard X-ray ptychographic coherent diffractive imaging has been performed at the P10 beamline of the PETRA III synchrotron to demonstrate the potential of a very wide dynamic range imaging X-ray detector (the Mixed-Mode Pixel Array Detector, or MM-PAD). The detector is capable of single photon detection, detecting fluxes exceeding 1 × 108 8-keV photons pixel−1 s−1, and framing at 1 kHz. A ptychographic reconstruction was performed using a peak focal intensity on the order of 1 × 1010 photons µm−2 s−1 within an area of approximately 325 nm × 603 nm. This was done without need of a beam stop and with a very modest attenuation, while ‘still’ images of the empty beam far-field intensity were recorded without any attenuation. The treatment of the detector frames and CDI methodology for reconstruction of non-sensitive detector regions, partially also extending the active detector area, are described. PMID:25178008

  6. Coherent imaging at resolution beyond diffraction limit using post-experimental data extrapolation

    CERN Document Server

    Latychevskaia, Tatiana

    2013-01-01

    Classical microscopy, regardless if photons or electrons are used, is based on incoherent optics and the microscopic record represents a distribution of added intensities. Local information of the sample is thus mapped onto local information at the detector. The resultant image exhibits a resolution ultimately limited by the Abbe criterion respectively by the numerical aperture of the microscope for a given wavelength. A number of super-resolution techniques in near as well as in the far-field have been proposed which allow imaging beyond the Abbe resolution limit. In contrast to classical optical microscopy in coherent microscopy, like holography or coherent diffraction, the superposition principle of waves holds, implying that field amplitudes are added, not intensities. The superposition of waves, be it light or deBroglie waves, leads to a non-local representation of the microscopic object information, an interference pattern spread out in space beyond the scattering object. Here we show a novel super-reso...

  7. In vitro birefringence imaging with spectral domain polarization-sensitive optical coherence tomography

    Institute of Scientific and Technical Information of China (English)

    Qiang Gong; Chuanmao Fan; Fan Zhang; Jianquan Yao

    2008-01-01

    Spectral domain polarization-sensitive optical coherence tomography (SDPS-OCT) is a depth-resolved polarization-sensitive interferometry which integrates polarization optics into spectral domain optical co-herence tomography (SD-OCT). This configuration can obtain birefringence information of samples and improve the imaging speed. In this paper, horizontally polarized light is used to replace natural light of the source. Then, right-rotated circularly polarized light is the incident sample light. To obtain two orthogonal components of the polarized interferogram, the reflected light of the reference arm is set to be 45° linearly polarized light. These two components are acquired by two spectrometers synchronously. The system was employed to achieve 12.8-#m axial resolution and 4.36-#m transverse resolution. We have imaged in vitro chicken tendon and muscle tissues with these system.

  8. Change Detection of High Resolution SAR Images by the Fusion of Coherent/Incoherent Information

    Directory of Open Access Journals (Sweden)

    Yang Xiang-li

    2015-10-01

    Full Text Available Aiming at detecting the change regions of high resolution Synthetic Aperture Radar (SAR images, we propose to use the Dempster-Shafer (D-S evidence theory to fuse coherent/incoherent features from sensors that form an integral part of the system. First, we use the Simple Linear Iterative Clustering (SLIC segmentation algorithm to implement multi-scale joint segmentation for multi-temporal SAR images. Second, we extract multiple intensity and coherence difference features on each segment level by SLIC using mean operator to complete the fusion of multi-scale features to get the multi-feature difference mapped by a ratio operator. Finally, we fuse the multi-feature difference maps to get the final change detection result using the D-S evidence theory. The experimental results in our study prove the effectiveness of our proposed computational algorithm.

  9. Imaging of complex density in silver nanocubes by coherent x-ray diffraction

    Science.gov (United States)

    Harder, R.; Liang, M.; Sun, Y.; Xia, Y.; Robinson, I. K.

    2010-03-01

    When using coherent x-rays to perform lensless imaging, it is the complex wave field exiting the sample or, in the case of the Bragg geometry, the deformed electron density distribution of a crystal, that is being sought. For most samples, to some extent, the image will be complex, containing both an amplitude and phase variation across the sample. We have developed versions of the hybrid input-output (HIO) and error reduction (ER) algorithms that are very robust for the inversion to complex objects from three-dimensional (3D) coherent x-ray diffraction (CXD) data measured around a Bragg spot of a small crystal. The development and behavior of these algorithms will be discussed in the context of inverting a 3D CXD pattern measured around a (111) Bragg spot of a silver nanocube.

  10. An all-fiber image-reject homodyne coherent Doppler wind lidar

    DEFF Research Database (Denmark)

    Foroughi Abari, Farzad; Pedersen, Anders Tegtmeier; Mann, Jakob

    2014-01-01

    In this paper, we present an alternative approach to the down-conversion (translation) of the received optical signals collected by the antenna of an all-fiber coherent Doppler lidar (CDL). The proposed method, widely known as image-reject, quadrature detection, or in-phase/quadrature-phase detec......In this paper, we present an alternative approach to the down-conversion (translation) of the received optical signals collected by the antenna of an all-fiber coherent Doppler lidar (CDL). The proposed method, widely known as image-reject, quadrature detection, or in......-phase/quadrature-phase detection, utilizes the advances in fiber optic communications such that the received signal can be optically down-converted into baseband where not only the radial velocity but also the direction of the movement can be inferred. In addition, we show that by performing a cross-spectral analysis, enabled...

  11. Noncontact photoacoustic imaging achieved by using a low-coherence interferometer as the acoustic detector.

    Science.gov (United States)

    Wang, Yi; Li, Chunhui; Wang, Ruikang K

    2011-10-15

    We report on a noncontact photoacoustic imaging (PAI) technique in which a low-coherence interferometer [(LCI), optical coherence tomography (OCT) hardware] is utilized as the acoustic detector. A synchronization approach is used to lock the LCI system at its highly sensitive region for photoacoustic detection. The technique is experimentally verified by the imaging of a scattering phantom embedded with hairs and the blood vessels within a mouse ear in vitro. The system's axial and lateral resolutions are evaluated at 60 and 30 μm, respectively. The experimental results indicate that PAI in a noncontact detection mode is possible with high resolution and high bandwidth. The proposed approach lends itself to a natural integration of PAI with OCT, rather than a combination of two separate and independent systems.

  12. High-resolution imaging of biological tissue with full-field optical coherence tomography

    Science.gov (United States)

    Zhu, Yue; Gao, Wanrong

    2015-03-01

    A new full-field optical coherence tomography system with high-resolution has been developed for imaging of cells and tissues. Compared with other FF-OCT (Full-field optical coherence tomography, FF-OCT) systems illuminated with optical fiber bundle, the improved Köhler illumination arrangement with a halogen lamp was used in the proposed FF-OCT system. High numerical aperture microscopic objectives were used for imaging and a piezoelectric ceramic transducer (PZT) was used for phase-shifting. En-face tomographic images can be obtained by applying the five-step phase-shifting algorithm to a series of interferometric images which are recorded by a smart camera. Three-dimensional images can be generated from these tomographic images. Imaging of the chip of Intel Pentium 4 processor demonstrated the ultrahigh resolution of the system (lateral resolution is 0.8μm ), which approaches the theoretical resolution 0.7 μm× 0.5 μm (lateral × axial). En-face images of cells of onion show an excellent performance of the system in generating en-face images of biological tissues. Then, unstained pig stomach was imaged as a tissue and gastric pits could be easily recognized using FF-OCT system. Our study provides evidence for the potential ability of FFOCT in identifying gastric pits from pig stomach tissue. Finally, label-free and unstained ex vivo human liver tissues from both normal and tumor were imaged with this FFOCT system. The results show that the setup has the potential for medical diagnosis applications such liver cancer diagnosis.

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

    Science.gov (United States)

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

    2017-02-01

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

  14. Single myelin fiber imaging in living rodents without labeling by deep optical coherence microscopy

    Science.gov (United States)

    Ben Arous, Juliette; Binding, Jonas; Léger, Jean-François; Casado, Mariano; Topilko, Piotr; Gigan, Sylvain; Claude Boccara, A.; Bourdieu, Laurent

    2011-11-01

    Myelin sheath disruption is responsible for multiple neuropathies in the central and peripheral nervous system. Myelin imaging has thus become an important diagnosis tool. However, in vivo imaging has been limited to either low-resolution techniques unable to resolve individual fibers or to low-penetration imaging of single fibers, which cannot provide quantitative information about large volumes of tissue, as required for diagnostic purposes. Here, we perform myelin imaging without labeling and at micron-scale resolution with >300-μm penetration depth on living rodents. This was achieved with a prototype [termed deep optical coherence microscopy (deep-OCM)] of a high-numerical aperture infrared full-field optical coherence microscope, which includes aberration correction for the compensation of refractive index mismatch and high-frame-rate interferometric measurements. We were able to measure the density of individual myelinated fibers in the rat cortex over a large volume of gray matter. In the peripheral nervous system, deep-OCM allows, after minor surgery, in situ imaging of single myelinated fibers over a large fraction of the sciatic nerve. This allows quantitative comparison of normal and Krox20 mutant mice, in which myelination in the peripheral nervous system is impaired. This opens promising perspectives for myelin chronic imaging in demyelinating diseases and for minimally invasive medical diagnosis.

  15. Single myelin fiber imaging in living rodents without labeling by deep optical coherence microscopy.

    Science.gov (United States)

    Ben Arous, Juliette; Binding, Jonas; Léger, Jean-François; Casado, Mariano; Topilko, Piotr; Gigan, Sylvain; Boccara, A Claude; Bourdieu, Laurent

    2011-11-01

    Myelin sheath disruption is responsible for multiple neuropathies in the central and peripheral nervous system. Myelin imaging has thus become an important diagnosis tool. However, in vivo imaging has been limited to either low-resolution techniques unable to resolve individual fibers or to low-penetration imaging of single fibers, which cannot provide quantitative information about large volumes of tissue, as required for diagnostic purposes. Here, we perform myelin imaging without labeling and at micron-scale resolution with >300-μm penetration depth on living rodents. This was achieved with a prototype [termed deep optical coherence microscopy (deep-OCM)] of a high-numerical aperture infrared full-field optical coherence microscope, which includes aberration correction for the compensation of refractive index mismatch and high-frame-rate interferometric measurements. We were able to measure the density of individual myelinated fibers in the rat cortex over a large volume of gray matter. In the peripheral nervous system, deep-OCM allows, after minor surgery, in situ imaging of single myelinated fibers over a large fraction of the sciatic nerve. This allows quantitative comparison of normal and Krox20 mutant mice, in which myelination in the peripheral nervous system is impaired. This opens promising perspectives for myelin chronic imaging in demyelinating diseases and for minimally invasive medical diagnosis.

  16. Low-kilovolt coherent electron diffractive imaging instrument based on a single-atom electron source

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chun-Yueh [Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Chang, Wei-Tse; Chen, Yi-Sheng; Hwu, En-Te; Chang, Chia-Seng; Hwang, Ing-Shouh, E-mail: ishwang@phys.sinica.edu.tw [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China); Hsu, Wei-Hao [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2016-03-15

    In this work, a transmission-type, low-kilovolt coherent electron diffractive imaging instrument was constructed. It comprised a single-atom field emitter, a triple-element electrostatic lens, a sample holder, and a retractable delay line detector to record the diffraction patterns at different positions behind the sample. It was designed to image materials thinner than 3 nm. The authors analyzed the asymmetric triple-element electrostatic lens for focusing the electron beams and achieved a focused beam spot of 87 nm on the sample plane at the electron energy of 2 kV. High-angle coherent diffraction patterns of a suspended graphene sample corresponding to (0.62 Å){sup −1} were recorded. This work demonstrated the potential of coherent diffractive imaging of thin two-dimensional materials, biological molecules, and nano-objects at a voltage between 1 and 10 kV. The ultimate goal of this instrument is to achieve atomic resolution of these materials with high contrast and little radiation damage.

  17. Three-dimensional coherent X-ray diffraction imaging of a whole, frozen-hydrated cell

    CERN Document Server

    Rodriguez, Jose A; Chen, Chien-Chun; Huang, Zhifeng; Jiang, Huaidong; Raines, Kevin S; Nam, Daewoong; Chen, Allan L; Pryor, A J; Wiegart, Lutz; Song, Changyong; Madsen, Anders; Chushkin, Yuriy; Zontone, Federico; Bradley, Peter J; Miao, Jianwei

    2014-01-01

    A structural understanding of whole cells in three dimensions at high spatial resolution remains a significant challenge and, in the case of X-rays, has been limited by radiation damage. By alleviating this limitation, cryogenic coherent diffraction imaging (cryo-CDI) could bridge the important resolution gap between optical and electron microscopy in bio-imaging. Here, we report for the first time 3D cryo-CDI of a whole, frozen-hydrated cell - in this case a Neospora caninum tachyzoite - using 8 keV X-rays. Our 3D reconstruction reveals the surface and internal morphology of the cell, including its complex, polarized sub-cellular architecture with a 3D resolution of ~75-100 nm, which is presently limited by the coherent X-ray flux and detector size. Given the imminent improvement in the coherent X-ray flux at the facilities worldwide, our work forecasts the possibility of routine 3D imaging of frozen-hydrated cells with spatial resolutions in the tens of nanometres.

  18. PSI Deformation Map Retrieval by Means of Temporal Sublook Coherence on Reduced Sets of SAR Images

    Directory of Open Access Journals (Sweden)

    Rubén Iglesias

    2015-01-01

    Full Text Available Prior to the application of any persistent scatterer interferometry (PSI technique for the monitoring of terrain displacement phenomena, an adequate pixel selection must be carried out in order to prevent the inclusion of noisy pixels in the processing. The rationale is to detect the so-called persistent scatterers, which are characterized by preserving their phase quality along the multi-temporal set of synthetic aperture radar (SAR images available. Two criteria are mainly available for the estimation of pixels’ phase quality, i.e., the coherence stability and the amplitude dispersion or permanent scatterers (PS approach. The coherence stability method allows an accurate estimation of the phase statistics, even when a reduced number of SAR acquisitions is available. Unfortunately, it requires the multi-looking of data during the coherence estimation, leading to a spatial resolution loss in the final results. In contrast, the PS approach works at full-resolution, but it demands a larger number of SAR images to be reliable, typically more than 20. There is hence a clear limitation when a full-resolution PSI processing is to be carried out and the number of acquisitions available is small. In this context, a novel pixel selection method based on exploiting the spectral properties of point-like scatterers, referred to as temporal sublook coherence (TSC, has been recently proposed. This paper seeks to demonstrate the advantages of employing PSI techniques by means of TSC on both orbital and ground-based SAR (GB-SAR data when the number of images available is small (10 images in the work presented. The displacement maps retrieved through the proposed technique are compared, in terms of pixel density and phase quality, with traditional criteria. Two X-band datasets composed of 10 sliding spotlight TerraSAR-X images and 10 GB-SAR images, respectively, over the landslide of El Forn de Canillo (Andorran Pyrenees, are employed for this study. For both

  19. Quantitative Chemically-Specific Coherent Diffractive Imaging of Buried Interfaces using a Tabletop EUV Nanoscope

    CERN Document Server

    Shanblatt, Elisabeth R; Gardner, Dennis F; Mancini, Giulia F; Karl, Robert M; Tanksalvala, Michael D; Bevis, Charles S; Vartanian, Victor H; Kapteyn, Henry C; Adams, Daniel E; Murnane, Margaret M

    2016-01-01

    Characterizing buried layers and interfaces is critical for a host of applications in nanoscience and nano-manufacturing. Here we demonstrate non-invasive, non-destructive imaging of buried interfaces using a tabletop, extreme ultraviolet (EUV), coherent diffractive imaging (CDI) nanoscope. Copper nanostructures inlaid in SiO2 are coated with 100 nm of aluminum, which is opaque to visible light and thick enough that neither optical microscopy nor atomic force microscopy can image the buried interfaces. Short wavelength (29 nm) high harmonic light can penetrate the aluminum layer, yielding high-contrast images of the buried structures. Moreover, differences in the absolute reflectivity of the interfaces before and after coating reveal the formation of interstitial diffusion and oxidation layers at the Al-Cu and Al-SiO2 boundaries. Finally, we show that EUV CDI provides a unique capability for quantitative, chemically-specific imaging of buried structures, and the material evolution that occurs at these buried ...

  20. Label-free imaging of developing vasculature in zebrafish with phase variance optical coherence microscopy

    Science.gov (United States)

    Chen, Yu; Fingler, Jeff; Trinh, Le A.; Fraser, Scott E.

    2016-03-01

    A phase variance optical coherence microscope (pvOCM) has been created to visualize blood flow in the vasculature of zebrafish embryos, without using exogenous labels. The pvOCM imaging system has axial and lateral resolutions of 2 μm in tissue, and imaging depth of more than 100 μm. Imaging of 2-5 days post-fertilization zebrafish embryos identified the detailed structures of somites, spinal cord, gut and notochord based on intensity contrast. Visualization of the blood flow in the aorta, veins and intersegmental vessels was achieved with phase variance contrast. The pvOCM vasculature images were confirmed with corresponding fluorescence microscopy of a zebrafish transgene that labels the vasculature with green fluorescent protein. The pvOCM images also revealed functional information of the blood flow activities that is crucial for the study of vascular development.

  1. Quantitative comparison of fuel spray images obtained using ultrafast coherent and incoherent double-pulsed illumination

    CERN Document Server

    Purwar, Harsh; Idlahcen, Saïd; Rozé, Claude; Blaisot, Jean-Bernard; Ménard, Thibault

    2015-01-01

    We present a quantitative comparison between the high-pressure fuel spray images obtained experimentally using classical imaging with coherent and incoherent ultrafast illuminations recorded using a compatible CMOS camera. The ultrafast, incoherent illumination source was extracted from the supercontinuum generated by tightly focusing the femtosecond laser pulses in water. The average velocity maps computed using time-correlated image-pairs and spray edge complexity computed using the average curvature scale space maps are compared for the spray images obtained with the two illumination techniques and also for the numerically simulated spray using the coupled volume of fluid and level set method for interface tracking (direct numerical simulation or DNS). The spray images obtained with supercontinuum-derived, incoherent, ultrafast illumination are clearer, since the artifacts arising due to laser speckles and multiple diffraction effects are largely reduced and show a better correlation with the DNS results.

  2. In vivo sectional imaging of the retinal periphery using conventional optical coherence tomography systems

    Directory of Open Access Journals (Sweden)

    Abhishek Kothari

    2012-01-01

    Full Text Available Optical coherence tomography (OCT has transformed macular disease practices. This report describes the use of conventional OCT systems for peripheral retinal imaging. Thirty-six eyes with peripheral retinal pathology underwent imaging with conventional OCT systems. In vivo sectional imaging of lattice degeneration, snail-track degeneration, and paving-stone degeneration was performed. Differences were noted between phenotypes of lattice degeneration. Several findings previously unreported in histopathology studies were encountered. Certain anatomic features were seen that could conceivably explain clinical and intraoperative behavior of peripheral lesions. Peripheral OCT imaging helped elucidate clinically ambiguous situations such as retinal breaks, subclinical retinal detachment, retinoschisis, choroidal nevus, and metastasis. Limitations of such scanning included end-gaze nystagmus and far peripheral lesions. This first of its kind study demonstrates the feasibility of peripheral retinal OCT imaging and expands the spectrum of indications for which OCT scanning may be clinically useful.

  3. XUV coherent diffraction imaging in reflection geometry with low numerical aperture.

    Science.gov (United States)

    Zürch, Michael; Kern, Christian; Spielmann, Christian

    2013-09-09

    We present an experimental realization of coherent diffraction imaging in reflection geometry illuminating the sample with a laser driven high harmonic generation (HHG) based XUV source. After recording the diffraction pattern in reflection geometry, the data must be corrected before the image can be reconstructed with a hybrid-input-output (HIO) algorithm. In this paper we present a detailed investigation of sources of spoiling the reconstructed image due to the nonlinear momentum transfer, errors in estimating the angle of incidence on the sample, and distortions by placing the image off center in the computation grid. Finally we provide guidelines for the necessary parameters to realize a satisfactory reconstruction within a spatial resolution in the range of one micron for an imaging scheme with a numerical aperture NA < 0.03.

  4. Adaptive anisotropic diffusion for noise reduction of phase images in Fourier domain Doppler optical coherence tomography.

    Science.gov (United States)

    Xia, Shaoyan; Huang, Yong; Peng, Shizhao; Wu, Yanfeng; Tan, Xiaodi

    2016-08-01

    Phase image in Fourier domain Doppler optical coherence tomography offers additional flow information of investigated samples, which provides valuable evidence towards accurate medical diagnosis. High quality phase images are thus desirable. We propose a noise reduction method for phase images by combining a synthetic noise estimation criteria based on local noise estimator (LNE) and distance median value (DMV) with anisotropic diffusion model. By identifying noise and signal pixels accurately and diffusing them with different coefficients respectively and adaptive iteration steps, we demonstrated the effectiveness of our proposed method in both phantom and mouse artery images. Comparison with other methods such as filtering method (mean, median filtering), wavelet method, probabilistic method and partial differential equation based methods in terms of peak signal-to-noise ratio (PSNR), equivalent number of looks (ENL) and contrast-to-noise ratio (CNR) showed the advantages of our method in reserving image energy and removing noise.

  5. Speckle Noise Reduction for the Enhancement of Retinal Layers in Optical Coherence Tomography Images

    Directory of Open Access Journals (Sweden)

    Fereydoon Nowshiravan Rahatabad

    2015-09-01

    Full Text Available Introduction One of the most important pre-processing steps in optical coherence tomography (OCT is reducing speckle noise, resulting from multiple scattering of tissues, which degrades the quality of OCT images. Materials and Methods The present study focused on speckle noise reduction and edge detection techniques. Statistical filters with different masks and noise variances were applied on OCT and test images. Objective evaluation of both types of images was performed, using various image metrics such as peak signal-to-noise ratio (PSNR, root mean square error, correlation coefficient and elapsed time. For the purpose of recovery, Kuan filter was used as an input for edge enhancement. Also, a spatial filter was applied to improve image quality. Results The obtained results were presented as statistical tables and images. Based on statistical measures and visual quality of OCT images, Enhanced Lee filter (3×3 with a PSNR value of 43.6735 in low noise variance and Kuan filter (3×3 with a PSNR value of 37.2850 in high noise variance showed superior performance over other filters. Conclusion Based on the obtained results, by using speckle reduction filters such as Enhanced Lee and Kuan filters on OCT images, the number of compounded images, required to achieve a given image quality, could be reduced. Moreover, use of Kuan filters for promoting the edges allowed smoothing of speckle regions, while preserving image tissue texture.

  6. 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

    2008-01-01

    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...

  7. Detecting coherent patterns in a flume by using PIV and IR imaging techniques

    Energy Technology Data Exchange (ETDEWEB)

    Gurka, Roi [Multiphase Flow Laboratory, Mechanical Engineering Department, Technion-IIT, 32000, Haifa (Israel); Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD (United States); Liberzon, Alex [Multiphase Flow Laboratory, Mechanical Engineering Department, Technion-IIT, 32000, Haifa (Israel); Institute of Hydromechanics and Water Resources Management, ETH Zuerich (Switzerland); Hetsroni, Gad [Multiphase Flow Laboratory, Mechanical Engineering Department, Technion-IIT, 32000, Haifa (Israel)

    2004-08-01

    We investigated the flow field in a turbulent boundary layer in a flume, by using Particle Image Velocimetry (PIV) and Hot-Foil Infrared Imaging (HFIRI) techniques. Coherent patterns in the flow were identified and characterized by using instantaneous velocity and temperature fields. The velocity fields in the streamwise-spanwise plane were measured in parallel to the temperature distribution of the flume bottom. The identified patterns are represented by means of their spatial characteristics - a non-dimensional spatial separation between streamwise patterns, {lambda}{sup +}. (orig.)

  8. Image steganography based on 2k correction and coherent bit length

    Science.gov (United States)

    Sun, Shuliang; Guo, Yongning

    2014-10-01

    In this paper, a novel algorithm is proposed. Firstly, the edge of cover image is detected with Canny operator and secret data is embedded in edge pixels. Sorting method is used to randomize the edge pixels in order to enhance security. Coherent bit length L is determined by relevant edge pixels. Finally, the method of 2k correction is applied to achieve better imperceptibility in stego image. The experiment shows that the proposed method is better than LSB-3 and Jae-Gil Yu's in PSNR and capacity.

  9. Application of optical coherence tomography attenuation imaging for quantification of optical properties in medulloblastoma

    Science.gov (United States)

    Vuong, Barry; Skowron, Patryk; Kiehl, Tim-Rasmus; Kyan, Matthew; Garzia, Livia; Genis, Helen; Sun, Cuiru; Taylor, Michael D.; Yang, Victor X. D.

    2015-03-01

    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.

  10. 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

    2009-01-01

    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.

  11. Dual-modality photothermal optical coherence tomography and magnetic-resonance imaging of carbon nanotubes.

    Science.gov (United States)

    Tucker-Schwartz, Jason M; Hong, Tu; Colvin, Daniel C; Xu, Yaqiong; Skala, Melissa C

    2012-03-01

    We demonstrate polyethylene-glycol-coated single-walled carbon nanotubes (CNTs) as contrast agents for both photothermal optical coherence tomography (OCT) and magnetic-resonance imaging (MRI). Photothermal OCT was accomplished with a spectral domain OCT system with an amplitude-modulated 750 nm pump beam using 10 mW of power, and T(2) MRI was achieved with a 4.7 T animal system. Photothermal OCT and T(2) MRI achieved sensitivities of nanomolar concentrations to CNTs dispersed in amine-terminated polyethylene glycol, thus establishing the potential for dual-modality molecular imaging with CNTs.

  12. High-resolution retinal imaging using adaptive optics and Fourier-domain optical coherence tomography

    Science.gov (United States)

    Olivier, Scot S.; Werner, John S.; Zawadzki, Robert J.; Laut, Sophie P.; Jones, Steven M.

    2010-09-07

    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.

  13. 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

    2005-01-01

    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.

  14. In situ 24 kHz coherent imaging of morphology change in laser percussion drilling.

    Science.gov (United States)

    Webster, Paul J L; Yu, Joe X Z; Leung, Ben Y C; Anderson, Mitchell D; Yang, Victor X D; Fraser, James M

    2010-03-01

    We observe sample morphology changes in real time (24 kHz) during and between percussion drilling pulses by integrating a low-coherence microscope into a laser micromachining platform. Nonuniform cut speed and sidewall evolution in stainless steel are observed to strongly depend on assist gas. Interpulse morphology relaxation such as hole refill is directly imaged, showing dramatic differences in the material removal process dependent on pulse duration/peak power (micros/0.1 kW, ps/20 MW) and material (steel, lead zirconate titanate PZT). Blind hole depth precision is improved by over 1 order of magnitude using in situ feedback from the imaging system.

  15. Three-dimensional imaging of artificial fingerprint by optical coherence tomography

    Science.gov (United States)

    Larin, Kirill V.; Cheng, Yezeng

    2008-03-01

    Fingerprint recognition is one of the popular used methods of biometrics. However, due to the surface topography limitation, fingerprint recognition scanners are easily been spoofed, e.g. using artificial fingerprint dummies. Thus, biometric fingerprint identification devices need to be more accurate and secure to deal with different fraudulent methods including dummy fingerprints. Previously, we demonstrated that Optical Coherence Tomography (OCT) images revealed the presence of the artificial fingerprints (made from different household materials, such as cement and liquid silicone rubber) at all times, while the artificial fingerprints easily spoofed the commercial fingerprint reader. Also we demonstrated that an analysis of the autocorrelation of the OCT images could be used in automatic recognition systems. Here, we exploited the three-dimensional (3D) imaging of the artificial fingerprint by OCT to generate vivid 3D image for both the artificial fingerprint layer and the real fingerprint layer beneath. With the reconstructed 3D image, it could not only point out whether there exists an artificial material, which is intended to spoof the scanner, above the real finger, but also could provide the hacker's fingerprint. The results of these studies suggested that Optical Coherence Tomography could be a powerful real-time noninvasive method for accurate identification of artificial fingerprints real fingerprints as well.

  16. CMOS detector arrays in a virtual 10-kilopixel camera for coherent terahertz real-time imaging.

    Science.gov (United States)

    Boppel, Sebastian; Lisauskas, Alvydas; Max, Alexander; Krozer, Viktor; Roskos, Hartmut G

    2012-02-15

    We demonstrate the principle applicability of antenna-coupled complementary metal oxide semiconductor (CMOS) field-effect transistor arrays as cameras for real-time coherent imaging at 591.4 GHz. By scanning a few detectors across the image plane, we synthesize a focal-plane array of 100×100 pixels with an active area of 20×20 mm2, which is applied to imaging in transmission and reflection geometries. Individual detector pixels exhibit a voltage conversion loss of 24 dB and a noise figure of 41 dB for 16 μW of the local oscillator (LO) drive. For object illumination, we use a radio-frequency (RF) source with 432 μW at 590 GHz. Coherent detection is realized by quasioptical superposition of the image and the LO beam with 247 μW. At an effective frame rate of 17 Hz, we achieve a maximum dynamic range of 30 dB in the center of the image and more than 20 dB within a disk of 18 mm diameter. The system has been used for surface reconstruction resolving a height difference in the μm range.

  17. Imaging resin infiltration into non-cavitated carious lesions by optical coherence tomography.

    Science.gov (United States)

    Schneider, Hartmut; Park, Kyung-Jin; Rueger, Claudia; Ziebolz, Dirk; Krause, Felix; Haak, Rainer

    2017-05-01

    Visualisation of the etching process and resin penetration at white spot carious lesions by spectral domain optical coherence tomography (SD-OCT). The non-cavitated carious lesions (ICDAS code 2) of four visually preselected extracted human molars and premolars were verified as enamel lesions by micro computed tomography (μCT). One region of interest (ROI) per tooth was marked by two drill-holes in occlusal-cervical direction. The lesions were imaged by SD-OCT. Lesions were infiltrated (Icon, DMG) according to the manufacturer's instructions. During each treatment step and after light curing of the infiltrant, the ROIs were imaged again by SD-OCT. Teeth were sectioned through the ROIs and section layers were imaged by scanning electron microscopy in order to compare with the OCT images. The image sequences for etching and infiltration were viewed in time lapse. During the etching process, numerous bubbles formed on the lesion surface. Using OCT, the process of resin penetration into the carious lesion body became visible. The early enamel carious lesion was completely infiltrated by the resin whereas infiltration of the advanced enamel carious lesion was incomplete and inhomogeneous. Resin infiltration can be increased by optimizing the etching process. Optical coherence tomography provides information about the process and degree of resin infiltration. Active acid application before resin infiltration is recommendable. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Paritosh Pande

    2016-01-01

    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.

  19. Spectral domain optical coherence tomography imaging of spectacular ecdysis in the royal python (Python regius).

    Science.gov (United States)

    Tusler, Charlotte A; Maggs, David J; Kass, Philip H; Paul-Murphy, Joanne R; Schwab, Ivan R; Murphy, Christopher J

    2015-01-01

    To describe using spectral domain optical coherence tomography (SD-OCT), digital slit-lamp biomicroscopy, and external photography, changes in the ophidian cuticle, spectacle, and cornea during ecdysis. Four normal royal pythons (Python regius). Snakes were assessed once daily throughout a complete shed cycle using nasal, axial, and temporal SD-OCT images, digital slit-lamp biomicroscopy, and external photography. Spectral domain optical coherence tomography (SD-OCT) images reliably showed the spectacular cuticle and stroma, subcuticular space (SCS), cornea, anterior chamber, iris, and Schlemm's canal. When visible, the subspectacular space (SSS) was more distended peripherally than axially. Ocular surface changes throughout ecdysis were relatively conserved among snakes at all three regions imaged. From baseline (7 days following completion of a full cycle), the spectacle gradually thickened before separating into superficial cuticular and deep, hyper-reflective stromal components, thereby creating the SCS. During spectacular separation, the stroma regained original reflectivity, and multiple hyper-reflective foci (likely fragments from the cuticular-stromal interface) were noted within the SCS. The cornea was relatively unchanged in character or thickness throughout all stages of ecdysis. Slit-lamp images did not permit observation of these changes. Spectral domain optical coherence tomography (SD-OCT) provided excellent high-resolution images of the snake anterior segment, and especially the cuticle, spectacle, and cornea of manually restrained normal snakes at all stages of ecdysis and warrants investigation in snakes with anterior segment disease. The peripheral spectacle may be the preferred entry point for diagnostic or therapeutic injections into the SSS and for initiating spectacular surgery. © 2014 American College of Veterinary Ophthalmologists.

  20. Phase-shift effect of amplitude spread function on spectrum and image formation in coherent Raman scattering microspectroscopy.

    Science.gov (United States)

    Fukutake, Naoki

    2016-03-01

    Coherent Raman scattering microspectroscopy, which includes coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS) microspectroscopy, permits label-free hyperspectral imaging. We report the theoretical study of the phase-shift effect of the impulse response function on the spectral and image-forming properties of coherent Raman scattering microspectroscopy. We show that the spectrum and image are influenced by not only the NA of objective for excitation (NA(ex)) but also that for signal collection (NA(col)), in association with the phase-shift effect. We discuss that, under the condition NA(ex)≠NA(col), both the spectrum and the image become deformed by the phase-shift effect, which can be applied to the direct measurement of the imaginary part of the nonlinear susceptibility in CARS spectroscopy. We point out that, even in SRS microscopy, the nonresonant background can contribute to the image formation and cause the artifact in the image.

  1. Optical coherence tomography imaging of psoriasis vulgaris: correlation with histology and disease severity

    DEFF Research Database (Denmark)

    Morsy, Hanan; Kamp, Søren; Thrane, Lars

    2010-01-01

    Epidermal thickness (ET) has been suggested as a surrogate measure of psoriasis severity. Optical coherence tomography (OCT) is a recent imaging technology that provides real-time skin images to a depth of 1.8 mm with a micrometre resolution. OCT may provide an accurate in vivo measure of ET. It is......, therefore, speculated that OCT may be used in the assessment of psoriasis vulgaris. A total of 23 patients with psoriasis vulgaris were systematically evaluated by OCT imaging and skin biopsy during treatment. Biopsies were graded for disease severity, and additional evaluation was done by the physician via...... with a stronger entrance signal, a serrated dermo-epidermal junction was found and a less signal intensity in the dermis as shown in OCT images. ET measured in untreated plaques was thicker reflecting epidermal hyperproliferation and inflammation. The changes were significantly correlated with the biopsy grading...

  2. Photonic Imaging with Optical Coherence Tomography for Quality Monitoring in the Poultry Industry: a Preliminary Study

    Directory of Open Access Journals (Sweden)

    M Sabuncu

    2015-09-01

    Full Text Available ABSTRACTA photonic imaging method that gives the possibility to measure egg quality was applied. Since the method is non-contact and non-destructive we believe that this photonic imaging method may be successfully integrated in the automated inspection systems in the poultry industry. The method involves scanning an invisible infrared light beam over the eggshell, allowing to detect possible cracks and reveal information about the structure of the eggshell. The high resolution, high quality measurements obtained through optical coherence tomography (OCT make it feasible to be utilized as part of an automated inspection system. In this paper we present an OCT scan image of the egg tip and reconstructed volumetric images of the eggshell surface. The method enables the detection of small cracks on eggs and reveals the detailed inner structures of the cracks.

  3. Correction of distortions in optical coherence tomography imaging of the eye

    Energy Technology Data Exchange (ETDEWEB)

    Podoleanu, Adrian [Applied Optics Group, University of Kent, Canterbury (United Kingdom); Charalambous, Ismini [Applied Optics Group, University of Kent, Canterbury (United Kingdom); Plesea, Lucian [Applied Optics Group, University of Kent, Canterbury (United Kingdom); Dogariu, Aristide [School of Optics, CREOL, University of Central Florida, Orlando, FL (United States); Rosen, Richard [Advanced Retinal Imaging Center, New York Eye and Ear Infirmary, NY (United States)

    2004-04-07

    Optical coherence tomography (OCT) images are affected by artefacts. These artefacts are the result of different factors such as refraction, curvature of the intermediate layers up to the depth of interest and the scanning procedure. The effect of such errors is different, depending on the way the image is acquired, either en-face or longitudinal OCT. We quantify the distortions by evaluating a lateral and an axial error. These measure the lateral and axial deviations of each image point from the object point inside the tissue. We show that the axial distortion can be larger than the achievable depth resolution in modern OCT systems. We have investigated these errors in imaging different tissue: cornea and retina in vivo and an intraocular lens in vitro.

  4. Textural analysis of optical coherence tomography skin images: quantitative differentiation between healthy and cancerous tissues

    Science.gov (United States)

    Adabi, Saba; Conforto, Silvia; Hosseinzadeh, Matin; Noe, Shahryar; Daveluy, Steven; Mehregan, Darius; Nasiriavanaki, Mohammadreza

    2017-02-01

    Optical Coherence Tomography (OCT) offers real-time high-resolution three-dimensional images of tissue microstructures. In this study, we used OCT skin images acquired from ten volunteers, neither of whom had any skin conditions addressing the features of their anatomic location. OCT segmented images are analyzed based on their optical properties (attenuation coefficient) and textural image features e.g., contrast, correlation, homogeneity, energy, entropy, etc. Utilizing the information and referring to their clinical insight, we aim to make a comprehensive computational model for the healthy skin. The derived parameters represent the OCT microstructural morphology and might provide biological information for generating an atlas of normal skin from different anatomic sites of human skin and may allow for identification of cell microstructural changes in cancer patients. We then compared the parameters of healthy samples with those of abnormal skin and classified them using a linear Support Vector Machines (SVM) with 82% accuracy.

  5. Delivery of picosecond lasers in multimode fibers for coherent anti-Stokes Raman scattering imaging.

    Science.gov (United States)

    Wang, Zhiyong; Yang, Yaliang; Luo, Pengfei; Gao, Liang; Wong, Kelvin K; Wong, Stephen T C

    2010-06-07

    We investigated the possibility of using standard commercial multimode fibers (MMF), Corning SMF28 fibers, to deliver picosecond excitation lasers for coherent anti-Stokes Raman scattering (CARS) imaging. We theoretically and/or experimentally analyzed issues associated with the fiber delivery, such as dispersion length, walk-off length, nonlinear length, average threshold power for self-phase modulations, and four-wave mixing (FWM). These analyses can also be applied to other types of fibers. We found that FWM signals are generated in MMF, but they can be filtered out using a long-pass filter for CARS imaging. Finally, we demonstrated that MMF can be used for delivery of picosecond excitation lasers in the CARS imaging system without any degradation of image quality.

  6. Morphology and epidermal thickness of normal skin imaged by optical coherence tomography

    DEFF Research Database (Denmark)

    Mogensen, Mette; Morsy, Hanan A.; Thrane, Lars;

    2008-01-01

    Background: Optical coherence tomography (OCT) is an optical imaging technology with a potential in the non-invasive diagnosis of skin cancer. To identify skin pathologies using OCT, it is of prime importance to establish baseline morphological features of normal skin. Aims: The aim of this study....... In glabrous skin the stratum corneum is visible. Children had larger ET (p skin-type-related differences in ET were found. Conclusion: This study contributes to understanding OCT and PS-OCT images of normal skin and indicates that OCT...... is to describe normal skin morphology using OCT and polarization-sensitive OCT (PS-OCT), which is a way of representing birefringent tissue such as collagen in OCT images. Anatomical locations in 20 healthy volunteers were imaged, and epidermal thickness (ET) was measured and compared to age, gender and skin...

  7. Wide-field optical coherence tomography based microangiography for retinal imaging

    Science.gov (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.

    2016-02-01

    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.

  8. In-line holography and coherent diffractive imaging with x-ray waveguides

    Science.gov (United States)

    de Caro, L.; Giannini, C.; Pelliccia, D.; Mocuta, C.; Metzger, T. H.; Guagliardi, A.; Cedola, A.; Burkeeva, I.; Lagomarsino, S.

    2008-02-01

    A Fresnel coherent diffraction imaging experiment with hard x rays is here presented, using two planar crossed waveguides as optical elements, leading to a virtual pointlike source. The coherent wave field obtained with this setup is used to illuminate a micrometric single object having the shape of a butterfly. A digital two-dimensional in-line holographic reconstruction of the unknown object at low resolution (200nm) has been obtained directly via fast Fourier transform (FFT) of the raw data. The object and its twin image are well separated because suitable geometrical conditions are satisfied. A good estimate of the incident wave field phase has been extracted directly from the FFT of the raw data. A partial object reconstruction with 50nm spatial resolution was achieved by fast iterative phase retrieval, the major limitation for a full reconstruction being the nonideal structure of the guided beam. The method offers a route for fast and reliable phase retrieval in x-ray coherent diffraction.

  9. Bright-Field Imaging and Optical Coherence Tomography of the Mouse Posterior Eye.

    Science.gov (United States)

    Krebs, Mark P; Xiao, Mei; Sheppard, Keith; Hicks, Wanda; Nishina, Patsy M

    2016-01-01

    Noninvasive live imaging has been used extensively for ocular phenotyping in mouse vision research. Bright-field imaging and optical coherence tomography (OCT) are two methods that are particularly useful for assessing the posterior mouse eye (fundus), including the retina, retinal pigment epithelium, and choroid, and are widely applied due to the commercial availability of sophisticated instruments and software. Here, we provide a guide to using these approaches with an emphasis on post-acquisition image processing using Fiji, a bundled version of the Java-based public domain software ImageJ. A bright-field fundus imaging protocol is described for acquisition of multi-frame videos, followed by image registration to reduce motion artifacts, averaging to reduce noise, shading correction to compensate for uneven illumination, filtering to improve image detail, and rotation to adjust orientation. An OCT imaging protocol is described for acquiring replicate volume scans, with subsequent registration and averaging to yield three-dimensional datasets that show reduced motion artifacts and enhanced detail. The Fiji algorithms used in these protocols are designed for batch processing and are freely available. The image acquisition and processing approaches described here may facilitate quantitative phenotyping of the mouse eye in drug discovery, mutagenesis screening, and the functional cataloging of mouse genes by individual laboratories and large-scale projects, such as the Knockout Mouse Phenotyping Project and International Mouse Phenotyping Consortium.

  10. Ultrasonic array imaging in nondestructive evaluation: total focusing method with using circular coherence factor

    Science.gov (United States)

    Zhang, Jie; Drinkwater, Bruce W.; Wilcox, Paul D.

    2013-01-01

    Ultrasonic array imaging algorithms have been widely used and developed in non-destructive evaluation in the last 10 years. In this paper, a widely-used imaging algorithms, Total Focusing Method (TFM), was further developed with using the phase statistical information of the scattering field from a scatterer, i.e., Circular Coherence Factor (CCF). TFM and TFM with using CCF are compared through both simulation and experimental measurements. In the simulation, array data sets were generated by using a hybrid forward model containing a single defect amongst a multitude of randomly distributed point scatterers to represent backscatter from material microstructure. The number of point scatterers per unit area and their scattering amplitude were optimized to reduce computation cost. The Signal to Noise Ratio (SNR) of the finial images and their resolution were used to indicate the quality of the different imaging algorithms. The images of different types of defect (point reflectors and planar cracks) were used to investigate the robustness of the imaging algorithms. It is shown that, with using CCF, higher image resolution can be achieved, but that the images of cracks are distorted. It is also shown that the detection limit of the imaging algorithms is almost equal for weakly scattering defects.

  11. Doppler coherence imaging of ion dynamics in VINETA.II and ASDEX-upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Gradic, Dorothea; Ford, Oliver; Wolf, Robert [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany); Lunt, Tilmann [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)

    2016-07-01

    In magnetically confining plasma experiments, diagnosis of ion flows is of great importance to measure the plasma response to the magnetic field or the exhaust particle flows in the divertor areas. Doppler coherence imaging spectroscopy (CIS) is a relatively new technique for the observation of plasma bulk ion dynamics. It is a passive optical diagnostic enabling line-integrated measurements to obtain 2D images of the ion flow and ion temperature. The general principle is similar to traditional Doppler spectroscopy, however CIS uses an imaging interferometer to perform narrow-bandwidth Fourier spectroscopy. A major advantage of the coherence imaging technique is the large amount of spatial information recovered. This allows tomographic inversion of the line-integrated measurements. With existing CIS setups, scrape-off-layer and high field side edge impurity flows could be observed in the MAST, core and edge poloidal He II flows in the WEGA stellarator and divertor impurity flows in DIII-D. The main objective of this study is the research of ion dynamics in the small linear plasma experiment VINETA.II and ASDEX-Upgrade. First Doppler CIS measurements from Ar-II plasma discharges in VINETA.II and He-II, C-III divertor flows in ASDEX-Upgrade and their preliminary interpretation will be presented.

  12. Fractal analysis of en face tomographic images obtained with full field optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Wanrong; Zhu, Yue [Department of Optical Engineering, Nanjing University of Science and Technology, Jiangsu (China)

    2017-03-15

    The quantitative modeling of the imaging signal of pathological areas and healthy areas is necessary to improve the specificity of diagnosis with tomographic en face images obtained with full field optical coherence tomography (FFOCT). In this work, we propose to use the depth-resolved change in the fractal parameter as a quantitative specific biomarker of the stages of disease. The idea is based on the fact that tissue is a random medium and only statistical parameters that characterize tissue structure are appropriate. We successfully relate the imaging signal in FFOCT to the tissue structure in terms of the scattering function and the coherent transfer function of the system. The formula is then used to analyze the ratio of the Fourier transforms of the cancerous tissue to the normal tissue. We found that when the tissue changes from the normal to cancerous the ratio of the spectrum of the index inhomogeneities takes the form of an inverse power law and the changes in the fractal parameter can be determined by estimating slopes of the spectra of the ratio plotted on a log-log scale. The fresh normal and cancer liver tissues were imaged to demonstrate the potential diagnostic value of the method at early stages when there are no significant changes in tissue microstructures. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Quantitative shear wave imaging optical coherence tomography for noncontact mechanical characterization of myocardium

    Science.gov (United States)

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

    2015-03-01

    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

  14. 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

  15. Real time endoscopic and functional imaging of biological ultrastructure using optical coherence tomography

    Science.gov (United States)

    Rollins, Andrew Martin

    2000-10-01

    Optical coherence tomography (OCT) is a relatively new, non-invasive optical imaging technique. OCT is well suited to in situ imaging of biological ultrastructure, providing micron-scale resolution in three dimensions to a depth of a few millimeters without contacting the tissue. The objective of this research was to advance the state of the art in OCT imaging in order to enable endoscopic examination of gastrointestinal mucosae, and to explore functional imaging extensions to the technology. We present a high speed OCT system capable of imaging in real time. Issues critical to real time OCT imaging are discussed, with an emphasis on rapid scanning optical delay lines, and real time signal conditioning, acquisition, and display instrumentation. Results of experiments demonstrating real time OCT imaging are presented, including in vivo samples. The real time OCT system was integrated with a custom catheter probe in a prototype endoscopic OCT (EOCT) unit appropriate for clinical studies. We report on the design and initial clinical experience with the real-time EOCT imaging system. Results of initial clinical studies are presented. EOCT imaging clearly delineates the substructure of the mucosa and submucosa in several gastrointestinal organs. Color Doppler optical coherence tomography (CDOCT) is a functional extension of OCT that can image flow in turbid media with micron-scale spatial resolution. We present a real-time CDOCT system that is capable of imaging flow at high frame rates. Imaging of flow in tissue simulating phantom and in vivo in an animal model is demonstrated. Further, we introduce a family of power-conserving fiber- optic interferometer designs for OCT. Simple design equations for optimization of the signal to noise ratio of the interferometers are expressed in terms of relevant signal and noise sources and measurable system parameters. Finally, we discuss a number of future directions for OCT research. The spectroscopic OCT techniques of wavelength

  16. Ex vivo and in vivo coherent Raman imaging of the peripheral and central nervous system

    Science.gov (United States)

    Huff, Terry Brandon

    A hallmark of nervous system disorders is damage or degradation of the myelin sheath. Unraveling the mechanisms underlying myelin degeneration and repair represent one of the great challenges in medicine. This thesis work details the development and utilization of advanced optical imaging methods to gain insight into the structure and function of myelin in both healthy and diseased states in the in vivo environment. This first part of this thesis discusses ex vivo studies of the effects of high-frequency stimulation of spinal tissues on the structure of the node of Ranvier as investigated by coherent anti-Stokes Raman scattering (CARS) imaging (manuscript submitted to Journal of Neurosciece). Reversible paranodal myelin retraction at the nodes of Ranvier was observed during 200 Hz electrical stimulation, beginning minutes after the onset and continuing for up to 10 min after stimulation was ceased. A mechanistic study revealed a Ca2+ dependent pathway: high-frequency stimulation induced paranodal myelin retraction via pathologic calcium influx into axons, calpain activation, and cytoskeleton degradation through spectrin break-down. Also, the construction of dual-scanning CARS microscope for large area mapping of CNS tissues is detailed (Optics Express, 2008, 16:19396-193409). A confocal scanning head equipped with a rotating polygon mirror provides high speed, high resolution imaging and is coupled with a motorized sample stage to generate high-resolution large-area images of mouse brain coronal section and guinea pig spinal cord cross section. The polygon mirror decreases the mosaic acquisition time significantly without reducing the resolution of individual images. The ex vivo studies are then extended to in vivo imaging of mouse sciatic nerve tissue by CARS and second harmonic generation (SHG) imaging (Journal of Microscopy, 2007, 225: 175-182). Following a minimally invasive surgery to open the skin, CARS imaging of myelinated axons and SHG imaging of the

  17. Imaging the anterior eye with dynamic-focus swept-source optical coherence tomography

    Science.gov (United States)

    Su, Johnny P.; Li, Yan; Tang, Maolong; Liu, Liang; Pechauer, Alex D.; Huang, David; Liu, Gangjun

    2015-12-01

    A custom-built dynamic-focus swept-source optical coherence tomography (SS-OCT) system with a central wavelength of 1310 nm was used to image the anterior eye from the cornea to the lens. An electrically tunable lens was utilized to dynamically control the positions of focusing planes over the imaging range of 10 mm. The B-scan images were acquired consecutively at the same position but with different focus settings. The B-scan images were then registered and averaged after filtering the out-of-focus regions using a Gaussian window. By fusing images obtained at different depth focus locations, high-resolution and high signal-strength images were obtained over the entire imaging depth. In vivo imaging of human anterior segment was demonstrated. The performance of the system was compared with two commercial OCT systems. The human eye ciliary body was better visualized with the dynamic-focusing SS-OCT system than using the commercial 840 and 1310 nm OCT systems. The sulcus-to-sulcus distance was measured, and the result agreed with that acquired with ultrasound biomicroscopy.

  18. In vivo imaging of nanoparticle delivery and tumor microvasculature with multimodal optical coherence tomography

    Science.gov (United States)

    Tucker-Schwartz, Jason M.; Beavers, Kelsey R.; Sit, Wesley W.; Shah, Amy T.; Duvall, Craig L.; Skala, Melissa C.

    2014-01-01

    Current imaging techniques capable of tracking nanoparticles in vivo supply either a large field of view or cellular resolution, but not both. Here, we demonstrate a multimodality imaging platform of optical coherence tomography (OCT) techniques for high resolution, wide field of view in vivo imaging of nanoparticles. This platform includes the first in vivo images of nanoparticle pharmacokinetics acquired with photothermal OCT (PTOCT), along with overlaying images of microvascular and tissue morphology. Gold nanorods (51.8 ± 8.1 nm by 15.2 ± 3.3 nm) were intravenously injected into mice, and their accumulation into mammary tumors was non-invasively imaged in vivo in three dimensions over 24 hours using PTOCT. Spatial frequency analysis of PTOCT images indicated that gold nanorods reached peak distribution throughout the tumors by 16 hours, and remained well-dispersed up to 24 hours post-injection. In contrast, the overall accumulation of gold nanorods within the tumors peaked around 16 hours post-injection. The accumulation of gold nanorods within the tumors was validated post-mortem with multiphoton microscopy. This shows the utility of PTOCT as part of a powerful multimodality imaging platform for the development of nanomedicines and drug delivery technologies. PMID:24940536

  19. Optical coherence tomography imaging of colonic crypts in a mouse model of colorectal cancer

    Science.gov (United States)

    Welge, Weston A.; Barton, Jennifer K.

    2016-03-01

    Aberrant crypt foci (ACF) are abnormal epithelial lesions that precede development of colonic polyps. As the earliest morphological change in the development of colorectal cancer, ACF is a highly studied phenomenon. The most common method of imaging ACF is chromoendoscopy using methylene blue as a contrast agent. Narrow- band imaging is a contrast-agent-free modality for imaging the colonic crypts. Optical coherence tomography (OCT) is an attractive alternative to chromoendoscopy and narrow-band imaging because it can resolve the crypt structure at sufficiently high sampling while simultaneously providing depth-resolved data. We imaged in vivo the distal 15 mm of colon in the azoxymethane (AOM) mouse model of colorectal cancer using a commercial swept-source OCT system and a miniature endoscope designed and built in-house. We present en face images of the colonic crypts and demonstrate that different patterns in healthy and adenoma tissue can be seen. These patterns correspond to those reported in the literature. We have previously demonstrated early detection of colon adenoma using OCT by detecting minute thickening of the mucosa. By combining mucosal thickness measurement with imaging of the crypt structure, OCT can be used to correlate ACF and adenoma development in space and time. These results suggest that OCT may be a superior imaging modality for studying the connection between ACF and colorectal cancer.

  20. Comprehensive vascular imaging using optical coherence tomography-based angiography and photoacoustic tomography

    Science.gov (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

    2016-09-01

    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.

  1. Imaging of the intact mouse cochlea by spectral domain optical coherence tomography

    Science.gov (United States)

    Gao, Simon S.; Yuan, Tao; Xia, Anping; Raphael, Patrick; Shelton, Ryan L.; Applegate, Brian E.; Oghalai, John S.

    2011-03-01

    Current medical imaging modalities, such as MRI and CT, do not provide high enough resolution to detect many changes within the cochlea that cause hearing loss. We sought to develop the technique of optical coherence tomography (OCT) to image the cochlea noninvasively and within its native environment. We used spectral domain OCT with 950 nm as the center wavelength and a bandwidth of ~100 nm to image freshly excised normal mouse cochlea at different developmental ages. The OCT system has an axial resolution of ~4 μm (in air) and a lateral resolution of ~10 μm. When we imaged normal adult mouse cochleae through the round window membrane, Reissner's membrane, the basilar membrane, the tectorial membrane, the spiral ligament, the spiral limbus, and the modiolus could be clearly identified. When we imaged intact adult cochleae, we were able to image through ~130 μm of bone and tissue to see up to a depth of ~600 μm, and all of the previously identified structures were still visible. Imaging of early postnatal mice during the timeline of cochlear development permitted visualization of the expected structural differences from adult cochleae. Therefore, we conclude that spectral domain OCT is an effective technique for noninvasive imaging of the murine cochlea.

  2. Circumferential optical coherence tomography angiography imaging of the swine esophagus using a micromotor balloon catheter.

    Science.gov (United States)

    Lee, Hsiang-Chieh; Ahsen, Osman Oguz; Liang, Kaicheng; Wang, Zhao; Cleveland, Cody; Booth, Lucas; Potsaid, Benjamin; Jayaraman, Vijaysekhar; Cable, Alex E; Mashimo, Hiroshi; Langer, Robert; Traverso, Giovanni; Fujimoto, James G

    2016-08-01

    We demonstrate a micromotor balloon imaging catheter for ultrahigh speed endoscopic optical coherence tomography (OCT) which provides wide area, circumferential structural and angiographic imaging of the esophagus without contrast agents. Using a 1310 nm MEMS tunable wavelength swept VCSEL light source, the system has a 1.2 MHz A-scan rate and ~8.5 µm axial resolution in tissue. The micromotor balloon catheter enables circumferential imaging of the esophagus at 240 frames per second (fps) with a ~30 µm (FWHM) spot size. Volumetric imaging is achieved by proximal pullback of the micromotor assembly within the balloon at 1.5 mm/sec. Volumetric data consisting of 4200 circumferential images of 5,000 A-scans each over a 2.6 cm length, covering a ~13 cm(2) area is acquired in <18 seconds. A non-rigid image registration algorithm is used to suppress motion artifacts from non-uniform rotational distortion (NURD), cardiac motion or respiration. En face OCT images at various depths can be generated. OCT angiography (OCTA) is computed using intensity decorrelation between sequential pairs of circumferential scans and enables three-dimensional visualization of vasculature. Wide area volumetric OCT and OCTA imaging of the swine esophagus in vivo is demonstrated.

  3. Broadband superluminescent diode–based ultrahigh resolution optical coherence tomography for ophthalmic imaging

    Science.gov (United States)

    Zhu, Dexi; Shen, Meixiao; Jiang, Hong; Li, Ming; Wang, Michael R.; Wang, Yuhong; Ge, Lili; Qu, Jia; Wang, Jianhua

    2011-01-01

    Spectral domain optical coherence tomography (SD-OCT) with ultrahigh resolution can be used to measure precise structures in the context of ophthalmic imaging. We designed an ultrahigh resolution SD-OCT system based on broadband superluminescent diode (SLD) as the light source. An axial resolution of 2.2 μm in tissue, a scan depth of 1.48 mm, and a high sensitivity of 93 dB were achieved by the spectrometer designed. The ultrahigh-resolution SD-OCT system was employed to image the human cornea and retina with a cross-section image of 2048 × 2048 pixels. Our research demonstrated that ultrahigh -resolution SD-OCT can be achieved using broadband SLD in a simple way. PMID:22191923

  4. Broadband superluminescent diode-based ultrahigh resolution optical coherence tomography for ophthalmic imaging.

    Science.gov (United States)

    Zhu, Dexi; Shen, Meixiao; Jiang, Hong; Li, Ming; Wang, Michael R; Wang, Yuhong; Ge, Lili; Qu, Jia; Wang, Jianhua

    2011-12-01

    Spectral domain optical coherence tomography (SD-OCT) with ultrahigh resolution can be used to measure precise structures in the context of ophthalmic imaging. We designed an ultrahigh resolution SD-OCT system based on broadband superluminescent diode (SLD) as the light source. An axial resolution of 2.2 μm in tissue, a scan depth of 1.48 mm, and a high sensitivity of 93 dB were achieved by the spectrometer designed. The ultrahigh-resolution SD-OCT system was employed to image the human cornea and retina with a cross-section image of 2048 × 2048 pixels. Our research demonstrated that ultrahigh -resolution SD-OCT can be achieved using broadband SLD in a simple way.

  5. Longitudinal three-dimensional visualisation of autoimmune diabetes by functional optical coherence imaging

    DEFF Research Database (Denmark)

    Berclaz, Corinne; Schmidt-Christensen, Anja; Szlag, Daniel

    2016-01-01

    AIMS/HYPOTHESIS: It is generally accepted that structural and functional quantitative imaging of individual islets would be beneficial to elucidate the pathogenesis of type 1 diabetes. We here introduce functional optical coherence imaging (FOCI) for fast, label-free monitoring of beta cell...... destruction and associated alterations of islet vascularisation. METHODS: NOD mouse and human islets transplanted into the anterior chamber of the eye (ACE) were imaged with FOCI, in which the optical contrast of FOCI is based on intrinsic variations of the index of refraction resulting in a faster...... diabetes-induced alterations of the islets. The label-free detection of beta cell volume and infiltration together with vascularisation offers a unique extension to study ACE-transplanted human islets. These results are contributing to a deeper understanding of human islet transplant rejection and label...

  6. Optical coherence tomography – near infrared spectroscopy system and catheter for intravascular imaging

    Science.gov (United States)

    Fard, Ali M.; Vacas-Jacques, Paulino; Hamidi, Ehsan; Wang, Hao; Carruth, Robert W.; Gardecki, Joseph A.; Tearney, Guillermo J.

    2013-01-01

    Owing to its superior resolution, intravascular optical coherence tomography (IVOCT) is a promising tool for imaging the microstructure of coronary artery walls. However, IVOCT does not identify chemicals and molecules in the tissue, which is required for a more complete understanding and accurate diagnosis of coronary disease. Here we present a dual-modality imaging system and catheter that uniquely combines IVOCT with diffuse near-infrared spectroscopy (NIRS) in a single dual-modality imaging device for simultaneous acquisition of microstructural and compositional information. As a proof-of-concept demonstration, the device has been used to visualize co-incident microstructural and spectroscopic information obtained from a diseased cadaver human coronary artery. PMID:24514658

  7. Optical coherence tomography imaging of psoriasis vulgaris: correlation with histology and disease severity

    DEFF Research Database (Denmark)

    Morsy, Hanan; Kamp, Søren; Thrane, Lars;

    2010-01-01

    Epidermal thickness (ET) has been suggested as a surrogate measure of psoriasis severity. Optical coherence tomography (OCT) is a recent imaging technology that provides real-time skin images to a depth of 1.8 mm with a micrometre resolution. OCT may provide an accurate in vivo measure of ET. It is...... with a stronger entrance signal, a serrated dermo-epidermal junction was found and a less signal intensity in the dermis as shown in OCT images. ET measured in untreated plaques was thicker reflecting epidermal hyperproliferation and inflammation. The changes were significantly correlated with the biopsy grading...... (r 2 = 0.41, p = 0.001) and ET significantly decreased with treatment (p = 0.0001). ET correlated significantly with self-reported measures of disease severity, but not with physician-assessed global PASI. The data suggest that OCT may be used to measure ET in psoriasis and the measurements correlate...

  8. Birefringence imaging of biological tissue by spectral domain polarization sensitive optical coherence tomography

    Science.gov (United States)

    Jing, Zhijun; Fan, Chuanmao; Jiang, Jingying; Gong, Qiang; Ma, Zhenhe; Zhang, Fan; Yao, Jianquan; Wang, R. K.

    2007-02-01

    A spectral domain Polarization sensitive optical coherence tomography (SDPS-OCT) system has been developed to acquire depth images of biological tissues such as porcine tendon, rabbit eye. The Stocks vectors (I, Q, U, and V) of the backscattered light from the biological tissues have been reconstructed. Further, the phase retardation and polarization degree between the two orthogonal polarizing states have been computed. Reconstructed images, i.e. birefringence images, from Stokes parameters, retardation and polarization degree of biological tissues show significant local variations in the polarization state. And the birefringence contrast of biological tissue possibly changes by some outside force. In addition, the local thickness of the birefringence layer determined with our system is significant. The results presented show SDPS-OCT is a potentially powerful technique to investigate tissue structural properties on the basis of the fact that any fibrous structure with biological tissues can influence the polarization state of light.

  9. 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.

    1992-01-01

    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...

  10. Enhancing effect of phase coherence factor for improvement of spatial resolution in ultrasonic imaging.

    Science.gov (United States)

    Hasegawa, Hideyuki

    2016-01-01

    Spatial resolution is one of the important factors that determines ultrasound image quality. In the present study, methods using the phase variance of ultrasonic echoes received by individual transducer elements have been examined for improvement of spatial resolution. An imaging method, i.e., phase coherence imaging, which uses the phase coherence factor (PCF) obtained from the phase variance of received ultrasonic echoes, was recently proposed. Spatial resolution is improved by weighting ultrasonic RF signals obtained by delay-and-sum (DAS) beam forming using PCF. In the present study, alternative PCFs, i.e., exponential PCF, harmonic PCF, and Gaussian PCF, have been proposed and examined for further improvement of spatial resolution. Spatial resolutions realized by the proposed PCFs were evaluated by an experiment using a phantom. The full widths at half maxima of the lateral profiles of an echo from a string phantom were 2.61 mm (DAS only), 1.46 mm (conventional PCF), and 0.48-0.62 mm (proposed PCFs). The PCFs newly proposed in the present study showed better spatial resolutions than the conventional PCF. The proposed PCFs also realized better visualization of echoes from a diffuse scattering medium than the conventional PCF.

  11. Ultrafast coherent diffractive imaging of nanoparticles using X-ray free-electron laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kassemeyer, Stephan

    2014-05-20

    Coherent diffractive imaging with X-ray free-electron lasers (X-FEL) promises high-resolution structure determination of single microscopic particles without the need for crystallization. The diffraction signal of small samples can be very weak, a difficulty that can not be countered by merely increasing the number of photons because the sample would be damaged by a high absorbed radiation dose. Traditional X-ray crystallography avoids this problem by bringing many sample particles into a periodic arrangement, which amplifies the individual signals while distributing the absorbed dose. Depending on the sample, however, crystallization can be very difficult or even impossible. This thesis presents algorithms for a new imaging approach using X-FEL radiation that works with single, non-crystalline sample particles. X-FELs can deliver X-rays with a peak brilliance many orders of magnitude higher than conventional X-ray sources, compensating for their weak interaction cross sections. At the same time, FELs can produce ultra-short pulses down to a few femtoseconds. In this way it is possible to perform ultra-fast imaging, essentially ''freezing'' the atomic positions in time and terminating the imaging process before the sample is destroyed by the absorbed radiation. This thesis primarily focuses on the three-dimensional reconstruction of single (and not necessarily crystalline) particles using coherent diffractive imaging at X-FELs: in order to extract three-dimensional information from scattering data, two-dimensional diffraction patterns from many different viewing angles must be combined. Therefore, the diffraction signal of many identical sample copies in random orientations is measured. The main result of this work is a globally optimal algorithm that can recover the sample orientations solely based on the diffraction signal, enabling three-dimensional imaging for arbitrary samples. The problem of finding three-dimensional orientations is

  12. Myocardial imaging using ultrahigh-resolution spectral domain optical coherence tomography

    Science.gov (United States)

    Yao, Xinwen; Gan, Yu; Marboe, Charles C.; Hendon, Christine P.

    2016-06-01

    We present an ultrahigh-resolution spectral domain optical coherence tomography (OCT) system in 800 nm with a low-noise supercontinuum source (SC) optimized for myocardial imaging. The system was demonstrated to have an axial resolution of 2.72 μm with a large imaging depth of 1.78 mm and a 6-dB falloff range of 0.89 mm. The lateral resolution (5.52 μm) was compromised to enhance the image penetration required for myocardial imaging. The noise of the SC source was analyzed extensively and an imaging protocol was proposed for SC-based OCT imaging with appreciable contrast. Three-dimensional datasets were acquired ex vivo on the endocardium side of tissue specimens from different chambers of fresh human and swine hearts. With the increased resolution and contrast, features such as elastic fibers, Purkinje fibers, and collagen fiber bundles were observed. The correlation between the structural information revealed in the OCT images and tissue pathology was discussed as well.

  13. Scattering angle resolved optical coherence tomography for in vivo murine retinal imaging

    Science.gov (United States)

    Gardner, Michael R.; Katta, Nitesh; McElroy, Austin; Baruah, Vikram; Rylander, H. G.; Milner, Thomas E.

    2017-02-01

    Optical coherence tomography (OCT) retinal imaging contributes to understanding central nervous system (CNS) diseases because the eye is an anatomical "window to the brain" with direct optical access to nonmylenated retinal ganglion cells. However, many CNS diseases are associated with neuronal changes beyond the resolution of standard OCT retinal imaging systems. Though studies have shown the utility of scattering angle resolved (SAR) OCT for particle sizing and detecting disease states ex vivo, a compact SAR-OCT system for in vivo rodent retinal imaging has not previously been reported. We report a fiber-based SAR-OCT system (swept source at 1310 nm +/- 65 nm, 100 kHz scan rate) for mouse retinal imaging with a partial glass window (center aperture) for angular discrimination of backscattered light. This design incorporates a dual-axis MEMS mirror conjugate to the ocular pupil plane and a high collection efficiency objective. A muring retina is imaged during euthanasia, and the proposed SAR-index is examined versus time. Results show a positive correlation between the SAR-index and the sub-cellular hypoxic response of neurons to isoflurane overdose during euthanasia. The proposed SAR-OCT design and image process technique offer a contrast mechanism able to detect sub-resolution neuronal changes for murine retinal imaging.

  14. Label-free imaging of human breast tissues using coherent anti-Stokes Raman scattering microscopy

    Science.gov (United States)

    Yang, Yaliang; Gao, Liang; Wang, Zhiyong; Thrall, Michael J.; Luo, Pengfei; Wong, Kelvin K.; Wong, Stephen T.

    2011-03-01

    Breast cancer is a common disease in women. Current imaging and diagnostic methods for breast cancer confront several limitations, like time-consuming, invasive and with a high cost. Alternative strategies are in high demand to alleviate patients' trauma and lower medical expenses. Coherent anti-Stokes Raman scattering (CARS) imaging technique offers many advantages, including label-free, sub-wavelength spatial resolution and video-rate imaging speed. Therefore, it has been demonstrated as a powerful tool for various biomedical applications. In this study, we present a label-free fast imaging method to identify breast cancer and its subtypes using CARS microscopy. Human breast tissues, including normal, benign and invasive carcinomas, were imaged ex vivo using a custom-built CARS microscope. Compared with results from corresponding hematoxylin and eosin (H&E) stains, the CARS technique has demonstrated its capability in identifying morphological features in a similar way as in H&E stain. These features can be used to distinguish breast cancer from normal and benign tissues, and further separate cancer subtypes from each other. Our pilot study suggests that CARS microscopy could be used as a routine examination tool to characterize breast cancer ex vivo. Moreover, its label-free and fast imaging properties render this technique as a promising approach for in vivo and real-time imaging and diagnosis of breast cancer.

  15. Intraocular lens alignment from an en face optical coherence tomography image Purkinje-like method

    Science.gov (United States)

    Sun, Mengchan; de Castro, Alberto; Ortiz, Sergio; Perez-Merino, Pablo; Birkenfeld, Judith; Marcos, Susana

    2014-06-01

    Measurement of intraocular lens (IOL) alignment implanted in patients in cataract surgery is important to understand their optical performance. We present a method to estimate tilt and decentration of IOLs based on optical coherence tomography (OCT) images. En face OCT images show Purkinje-like images that correspond to the specular reflections from the corneal and IOL surfaces. Unlike in standard Purkinje-imaging, the tomographic nature of OCT allows unequivocal association of the reflection with the corresponding surface. The locations of the Purkinje-like images are linear combinations of IOL tilt, IOL decentration, and eye rotation. The weighting coefficients depend on the individual anterior segment geometry, obtained from the same OCT datasets. The methodology was demonstrated on an artificial model eye with set amounts of lens tilt and decentration and five pseudophakic eyes. Measured tilt and decentration in the artificial eye differed by 3.7% and 0.9%, respectively, from nominal values. In patients, average IOL tilt and decentration from Purkinje were 3.30±4.68 deg and 0.16±0.16 mm, respectively, and differed on average by 0.5 deg and 0.09 mm, respectively, from direct measurements on distortion-corrected OCT images. Purkinje-based methodology from anterior segment en face OCT imaging provided, therefore, reliable measurements of IOL tilt and decentration.

  16. Cellular resolution volumetric in vivo retinal imaging with adaptive optics–optical coherence tomography◊

    Science.gov (United States)

    Zawadzki, Robert J.; Choi, Stacey S.; Fuller, Alfred R.; Evans, Julia W.; Hamann, Bernd; Werner, John S.

    2009-01-01

    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. PMID:19259248

  17. Cellular resolution volumetric in vivo retinal imaging with adaptive optics-optical coherence tomography.

    Science.gov (United States)

    Zawadzki, Robert J; Choi, Stacey S; Fuller, Alfred R; Evans, Julia W; Hamann, Bernd; Werner, John S

    2009-03-02

    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.

  18. Fully-automatic laser welding and micro-sculpting with universal in situ inline coherent imaging

    CERN Document Server

    Webster, Paul J L; Ji, Yang; Galbraith, Christopher M; Kinross, Alison W; Van Vlack, Cole; Fraser, James M

    2014-01-01

    Though new affordable high power laser technologies make possible many processing applications in science and industry, depth control remains a serious technical challenge. Here we show that inline coherent imaging, with line rates up to 312 kHz and microsecond-duration capture times, is capable of directly measuring laser penetration depth in a process as violent as kW-class keyhole welding. We exploit ICI's high speed, high dynamic range and robustness to interference from other optical sources to achieve fully automatic, adaptive control of laser welding as well as ablation, achieving micron-scale sculpting in vastly different heterogeneous biological materials.

  19. Automatic laser welding and milling with in situ inline coherent imaging.

    Science.gov (United States)

    Webster, P J L; Wright, L G; Ji, Y; Galbraith, C M; Kinross, A W; Van Vlack, C; Fraser, J M

    2014-11-01

    Although new affordable high-power laser technologies enable many processing applications in science and industry, depth control remains a serious technical challenge. In this Letter we show that inline coherent imaging (ICI), with line rates up to 312 kHz and microsecond-duration capture times, is capable of directly measuring laser penetration depth, in a process as violent as kW-class keyhole welding. We exploit ICI's high speed, high dynamic range, and robustness to interference from other optical sources to achieve automatic, adaptive control of laser welding, as well as ablation, achieving 3D micron-scale sculpting in vastly different heterogeneous biological materials.

  20. Imaging of human breast tissue using polarization sensitive optical coherence tomography

    Science.gov (United States)

    Verma, Y.; Gautam, M.; Divakar Rao, K.; Swami, M. K.; Gupta, P. K.

    2011-12-01

    We report a study on the use of polarization sensitive optical coherence tomography (PSOCT) for discriminating malignant (invasive ductal carcinoma), benign (fibroadenoma) and normal (adipocytes) breast tissue sites. The results show that while conventional OCT, that utilizes only the intensity of light back-scattered from tissue microstructures, is able to discriminate breast tissues as normal (adipocytes) and abnormal (malignant and benign) tissues, PS-OCT helps in discriminating between malignant and benign tissue sites also. The estimated values of birefringence obtained from the PSOCT imaging show that benign breast tissue samples have significantly higher birefringence as compared to the malignant tissue samples.

  1. Calibration-free B-scan images produced by master/slave optical coherence tomography

    OpenAIRE

    Bradu, Adrian; Podoleanu, Adrian G.H.

    2014-01-01

    We report on a novel method to produce B-scan images in spectral domain optical coherence tomography (SD-OCT). The method proceeds in two steps. In the first step, using a mirror in the sample arm of the interferometer, channeled spectra are acquired for different values of the optical path difference (OPD) and stored as masks. In the second step, the mirror is replaced with an object and the captured channelled spectrum is correlated with each mask, providing the interference strength from t...

  2. Extreme ultraviolet radiation for coherent diffractive imaging with high spatial resolution

    Institute of Scientific and Technical Information of China (English)

    L.V.; DAO; S.; TEICHMANN; B.; CHEN; R.A.; DILANIAN; K.B.; DINH; P.; HANNAFORD

    2010-01-01

    Using different noble gases,argon,neon and helium,we are able to generate by high-harmonic generation(HHG) just a few harmonic orders in the spectral range 10-35 nm with a photon flux of~2.10 12 photons/(harmonic cm2 s) for argon and~10 10 photons/(harmonic cm2 s) for helium. The few-harmonic-order radiation is used for coherent diffractive imaging directly without any spectral filter. A spatial resolution of~100 nm is achieved using a~30 nm HHG source.

  3. A Flexible Phase Retrieval Framework for Flux-limited Coherent X-Ray Imaging

    CERN Document Server

    Shi, Liang; Lane, Thomas J

    2016-01-01

    Coherent X-ray diffraction imaging~(CXDI) experiments are intrinsically limited by shot noise, a lack of prior knowledge about the sample's support, and missing measurements due to the experimental geometry. We propose a flexible, iterative phase retrieval framework that allows for accurate modeling of Gaussian or Poissonian noise statistics, modified support updates, regularization of reconstructed signals, and handling of missing data in the observations. The proposed method is efficiently solved using alternating direction method of multipliers~(ADMM) and is demonstrated to consistently outperform state-of-the-art algorithms for low-photon phase retrieval from CXDI experiments, both for simulated diffraction patterns and for experimental measurements.

  4. Validation of Dynamic optical coherence tomography for non-invasive, in vivo microcirculation imaging of the skin

    DEFF Research Database (Denmark)

    Themstrup, L.; Welzel, Julia; Ciardo, Silvana

    2016-01-01

    Objectives: Dynamic optical coherence tomography (D-OCT) is an angiographic variation of OCT that non-invasively provides images of the in vivo microvasculature of the skin by combining conventional OCT images with flow data. The objective of this study was to investigate and report on the D-OCT ...

  5. Scanning coherent diffractive imaging methods for actinic extreme ultraviolet mask metrology

    Science.gov (United States)

    Helfenstein, Patrick; Mohacsi, Istvan; Rajeev, Rajendran; Ekinci, Yasin

    2016-07-01

    For the successful implementation of extreme ultraviolet (EUV) lithography in the upcoming technology nodes, a major challenge to overcome is the stable and reliable detection and characterization of mask defects. We have recently presented a reflective mode EUV mask scanning lensless imaging tool (RESCAN) which was installed at the XIL-II beamline of the swiss light source and showed reconstructed aerial images of test patterns on EUV masks. RESCAN uses scanning coherent diffractive imaging (SCDI) methods to obtain actinic aerial images of EUV photomasks and was designed for 80 nm onmask resolution. Our SCDI algorithm reconstructs the measured sample by iteratively solving the phase problem using overdetermined diffraction data gathered by scanning across the specimen with a finite illumination. It provides the phase and amplitude aerial images of EUV photomasks with high resolution without the need to use high numerical aperture (NA) lenses. Contrary to scanning microscopy and full-field microscopy, where the resolution is limited by the spot size or NA of the lens, the achievable resolution with our method depends on the detector noise and NA of the detector. To increase the resolution of our tool, we upgraded RESCAN with a detector and algorithms. Here, we present the results obtained with the tool that is capable of up to 40-nm onmask resolution. We believe that the realization of our prototype marks a significant step toward overcoming the limitations imposed by methods relying on imaging optics and shows a viable solution for actinic mask metrology.

  6. Optical coherence tomography and hyperspectral imaging of vascular recovery in a model of peripheral arterial disease

    Science.gov (United States)

    Poole, Kristin M.; Sit, Wesley W.; Tucker-Schwartz, Jason M.; Duvall, Craig L.; Skala, Melissa C.

    2013-03-01

    Peripheral arterial disease (PAD) leads to an increased risk of myocardial infarction and stroke, increased mortality, and reduced quality of life. The mouse hind limb ischemia (HLI) model is the most commonly used system for studying the mechanisms of collateral vessel formation and for testing new PAD therapies, but there is a lack of techniques for acquiring physiologically-relevant, quantitative data intravitally in this model. In this work, non-invasive, quantitative optical imaging techniques were applied to the mouse HLI model over a time course. Optical coherence tomography (OCT) imaged changes in blood flow (Doppler OCT) and microvessel morphology (speckle variance OCT) through the skin of haired mice with high resolution. Hyperspectral imaging was also used to quantify blood oxygenation. In ischemic limbs, blood oxygenation in the footpad was substantially reduced after induction of ischemia followed by complete recovery by three weeks, consistent with standard measures. Three dimensional images of the vasculature distal to vessel occlusion acquired with speckle variance OCT revealed changes in OCT flow signal and vessel morphology. Taken together, OCT and hyperspectral imaging enable intravital acquisition of both functional and morphological data which fill critical gaps in understanding structure-function relationships that contribute to recovery in the mouse HLI model. Therefore, these optical imaging methods hold promise as tools for studying the mechanisms of vascular recovery and evaluating novel therapeutic treatments in preclinical studies.

  7. Segmentation of 830- and 1310-nm LASIK corneal optical coherence tomography images

    Science.gov (United States)

    Li, Yan; Shekhar, Raj; Huang, David

    2002-05-01

    Optical coherence tomography (OCT) provides a non-contact and non-invasive means to visualize the corneal anatomy at micron scale resolution. We obtained corneal images from an arc-scanning (converging) OCT system operating at a wavelength of 830nm and a fan-shaped-scanning high-speed OCT system with an operating wavelength of 1310nm. Different scan protocols (arc/fan) and data acquisition rates, as well as wavelength dependent bio-tissue backscatter contrast and optical absorption, make the images acquired using the two systems different. We developed image-processing algorithms to automatically detect the air-tear interface, epithelium-Bowman's layer interface, laser in-situ keratomileusis (LASIK) flap interface, and the cornea-aqueous interface in both kinds of images. The overall segmentation scheme for 830nm and 1310nm OCT images was similar, although different strategies were adopted for specific processing approaches. Ultrasound pachymetry measurements of the corneal thickness and Placido-ring based corneal topography measurements of the corneal curvature were made on the same day as the OCT examination. Anterior/posterior corneal surface curvature measurement with OCT was also investigated. Results showed that automated segmentation of OCT images could evaluate anatomic outcome of LASIK surgery.

  8. In vivo photothermal optical coherence tomography for non-invasive imaging of endogenous absorption agents.

    Science.gov (United States)

    Makita, Shuichi; Yasuno, Yoshiaki

    2015-05-01

    In vivo photothermal optical coherence tomography (OCT) is demonstrated for cross-sectional imaging of endogenous absorption agents. In order to compromise the sensitivity, imaging speed, and sample motion immunity, a new photothermal detection scheme and phase processing method are developed. Phase-resolved swept-source OCT and fiber-pigtailed laser diode (providing excitation at 406 nm) are combined to construct a high-sensitivity photothermal OCT system. OCT probe and excitation beam coaxially illuminate and are focused on tissues. The photothermal excitation and detection procedure is designed to obtain high efficiency of photothermal effect measurement. The principle and method of depth-resolved cross-sectional imaging of absorption agents with photothermal OCT has been derived. The phase-resolved thermal expansion detection algorithm without motion artifact enables in vivo detection of photothermal effect. Phantom imaging with a blood phantom and in vivo human skin imaging are conducted. A phantom with guinea-pig blood as absorber has been scanned by the photothermal OCT system to prove the concept of cross-sectional absorption agent imaging. An in vivo human skin measurement is also performed with endogenous absorption agents.

  9. Four-dimensional structural and Doppler optical coherence tomography imaging on graphics processing units.

    Science.gov (United States)

    Sylwestrzak, Marcin; Szlag, Daniel; Szkulmowski, Maciej; Gorczynska, Iwona; Bukowska, Danuta; Wojtkowski, Maciej; Targowski, Piotr

    2012-10-01

    The authors present the application of graphics processing unit (GPU) programming for real-time three-dimensional (3-D) Fourier domain optical coherence tomography (FdOCT) imaging with implementation of flow visualization algorithms. One of the limitations of FdOCT is data processing time, which is generally longer than data acquisition time. Utilizing additional algorithms, such as Doppler analysis, further increases computation time. The general purpose computing on GPU (GPGPU) has been used successfully for structural OCT imaging, but real-time 3-D imaging of flows has so far not been presented. We have developed software for structural and Doppler OCT processing capable of visualization of two-dimensional (2-D) data (2000 A-scans, 2048 pixels per spectrum) with an image refresh rate higher than 120 Hz. The 3-D imaging of 100×100 A-scans data is performed at a rate of about 9 volumes per second. We describe the software architecture, organization of threads, and optimization. Screen shots recorded during real-time imaging of a flow phantom and the human eye are presented.

  10. Distinguishing features of acute Vogt-Koyanagi-Harada disease and acute central serous chorioretinopathy on optical coherence tomography angiography and en face optical coherence tomography imaging.

    Science.gov (United States)

    Aggarwal, Kanika; Agarwal, Aniruddha; Deokar, Ankit; Mahajan, Sarakshi; Singh, Ramandeep; Bansal, Reema; Sharma, Aman; Dogra, Mangat R; Gupta, Vishali

    2017-12-01

    The aim of this study is to determine the differences in optical coherence tomography angiography (OCTA) features of acute Vogt-Koyanagi-Harada disease (VKH) and acute central serous chorioretinopathy (CSC). Clinical and imaging data of patients with acute CSC and VKH in a tertiary-care institute were analyzed. Multimodal imaging including fluorescein angiography, indocyanine green angiography (ICGA), and enhanced-depth imaging OCT were performed. OCTA images were analyzed for alterations in retinochoroidal microvasculature. Thirty-four eyes (24 patients; 10 with VKH and 14 with CSC) were included. OCTA en face images showed apparent areas of choriocapillaris flow void due to shadowing effect from overlying subretinal fluid and pigment epithelial detachment in CSC. However, eyes with VKH showed presence of true choriocapillaris flow void on OCTA that corresponded to choriocapillaris ischemia on ICGA. OCTA is a useful tool to assess choriocapillaris ischemia in VKH and is helpful to differentiate it from CSC in the acute stage.

  11. Lensless coherent imaging by sampling of the optical field with digital micromirror device

    Science.gov (United States)

    Vdovin, G.; Gong, H.; Soloviev, O.; Pozzi, P.; Verhaegen, M.

    2015-12-01

    We have experimentally demonstrated a lensless coherent microscope based on direct registration of the complex optical field by sampling the pupil with a sequence of two-point interferometers formed by a digital micromirror device. Complete registration of the complex amplitude in the pupil of the imaging system, without any reference beam, provides a convenient link between the experimental and computational optics. Unlike other approaches to digital holography, our method does not require any external reference beam, resulting in a simple and robust registration setup. Computer analysis of the experimentally registered field allows for focusing the image in the whole range from zero to infinity, and for virtual correction of the aberrations present in the real optical system, by applying the adaptive wavefront corrections to its virtual model.

  12. Classification of wet aged related macular degeneration using optical coherence tomographic images

    Science.gov (United States)

    Haq, Anam; Mir, Fouwad Jamil; Yasin, Ubaid Ullah; Khan, Shoab A.

    2013-12-01

    Wet Age related macular degeneration (AMD) is a type of age related macular degeneration. In order to detect Wet AMD we look for Pigment Epithelium detachment (PED) and fluid filled region caused by choroidal neovascularization (CNV). This form of AMD can cause vision loss if not treated in time. In this article we have proposed an automated system for detection of Wet AMD in Optical coherence tomographic (OCT) images. The proposed system extracts PED and CNV from OCT images using segmentation and morphological operations and then detailed feature set are extracted. These features are then passed on to the classifier for classification. Finally performance measures like accuracy, sensitivity and specificity are calculated and the classifier delivering the maximum performance is selected as a comparison measure. Our system gives higher performance using SVM as compared to other methods.

  13. Performance evaluation of an all-fiber image-reject homodyne coherent Doppler wind lidar

    Directory of Open Access Journals (Sweden)

    C. F. Abari

    2015-04-01

    Full Text Available The main purpose of this study is to evaluate the near-zero wind velocity measurement performance of two separate 1.5 μm all-fiber coherent Doppler lidars (CDL. The performance characterization is performed through the presentation of the results from two separate atmospheric field campaigns. In one campaign, a recently developed continuous wave (CW CDL benefiting from an image-reject front-end was deployed. The other campaign utilized a different CW CDL, benefiting from a heterodyne receiver with intermediate frequency (IF sampling. In both field campaigns the results are compared against a sonic anemometer, as the reference instrument. The measurements clearly show that the image-reject architecture results in more accurate measurements of radial wind velocities close to zero. Close-to-zero velocities are usually associated with the vertical component of the wind and are important to characterize.

  14. Intraoperative imaging of pediatric vocal fold lesions using optical coherence tomography

    Science.gov (United States)

    Benboujja, Fouzi; Garcia, Jordan A.; Beaudette, Kathy; Strupler, Mathias; Hartnick, Christopher J.; Boudoux, Caroline

    2016-01-01

    Optical coherence tomography (OCT) has been previously identified as a promising tool for exploring laryngeal pathologies in adults. Here, we present an OCT handheld probe dedicated to imaging the unique geometry involved in pediatric laryngoscopy. A vertical cavity surface emitting laser-based wavelength-swept OCT system operating at 60 frames per second was coupled to the probe to acquire three-dimensional (3-D) volumes in vivo. In order to evaluate the performance of the proposed probe and system, we imaged pediatric vocal fold lesions of patients going under direct laryngoscopy. Through this in vivo study, we extracted OCT features characterizing each pediatric vocal fold lesion, which shows a great potential for noninvasive laryngeal lesion discrimination. We believe OCT vocal fold examination in 3-D will result in improved knowledge of the pediatric anatomy and could aid in managing pediatric laryngeal diseases.

  15. Coherent x-ray imaging of spins on nanoscale (Conference Presentation)

    Science.gov (United States)

    Shpyrko, Oleg

    2016-10-01

    Understanding electronic structure at nanometer resolution is crucial to understanding physics such as phase separation and emergent behavior in correlated electron materials. Nondestructive probes which have the ability to see beyond surfaces on nanometer length and sub-picosecond time scales can greatly enhance our understanding of these systems and will impact development of future technologies, such as magnetic storage. Polarized x-rays are an appealing choice of probe due to their penetrating power, elemental and magnetic specificity, and high spatial resolution. The resolution of traditional x-ray microscopy is limited by the nanometer precision required to fabricate x-ray optics. In this thesis, a novel approach to lensless imaging of an extended magnetic nanostructure is presented. We demonstrate this approach by imaging ferrimagnetic "maze" domains in a Gd/Fe multilayer with perpendicular anisotropy. A series of dichroic coherent diffraction patterns, ptychographically recorded, are numerically inverted using non-convex and non-linear optimization theory, and we follow the magnetic domain configuration evolution through part of its magnetization hysteresis loop by applying an external magnetic field. Unlike holographic methods, it does not require a reference wave or precision optics, and so is a far simpler experiment. In addition, it enables the imaging of samples with arbitrarily large spatial dimensions, at a spatial resolution limited solely by the coherent x-ray flux and wavelength. It can readily be extended to other non-magnetic systems that exhibit circular or linear dichroism. This approach is scalable to imaging with diffraction-limited resolution, a prospect rapidly becoming a reality in view of the new generation of phenomenally brilliant x-ray sources.

  16. Tomography of a Cryo-immobilized Yeast Cell Using Ptychographic Coherent X-Ray Diffractive Imaging.

    Science.gov (United States)

    Giewekemeyer, K; Hackenberg, C; Aquila, A; Wilke, R N; Groves, M R; Jordanova, R; Lamzin, V S; Borchers, G; Saksl, K; Zozulya, A V; Sprung, M; Mancuso, A P

    2015-11-03

    The structural investigation of noncrystalline, soft biological matter using x-rays is of rapidly increasing interest. Large-scale x-ray sources, such as synchrotrons and x-ray free electron lasers, are becoming ever brighter and make the study of such weakly scattering materials more feasible. Variants of coherent diffractive imaging (CDI) are particularly attractive, as the absence of an objective lens between sample and detector ensures that no x-ray photons scattered by a sample are lost in a limited-efficiency imaging system. Furthermore, the reconstructed complex image contains quantitative density information, most directly accessible through its phase, which is proportional to the projected electron density of the sample. If applied in three dimensions, CDI can thus recover the sample's electron density distribution. As the extension to three dimensions is accompanied by a considerable dose applied to the sample, cryogenic cooling is necessary to optimize the structural preservation of a unique sample in the beam. This, however, imposes considerable technical challenges on the experimental realization. Here, we show a route toward the solution of these challenges using ptychographic CDI (PCDI), a scanning variant of coherent imaging. We present an experimental demonstration of the combination of three-dimensional structure determination through PCDI with a cryogenically cooled biological sample--a budding yeast cell (Saccharomyces cerevisiae)--using hard (7.9 keV) synchrotron x-rays. This proof-of-principle demonstration in particular illustrates the potential of PCDI for highly sensitive, quantitative three-dimensional density determination of cryogenically cooled, hydrated, and unstained biological matter and paves the way to future studies of unique, nonreproducible biological cells at higher resolution.

  17. Long working distance optical coherence tomography for pediatric imaging (Conference Presentation)

    Science.gov (United States)

    Qian, Ruobing; Carrasco-Zevallos, Oscar; Vajzovic, Lejla; Gramatikov, Boris I.; Guyton, David L.; Toth, Cynthia A.; Izatt, Joseph A.

    2016-03-01

    Conventional optical coherence tomography (OCT) systems have working distances of about 25 mm, and require cooperative subjects to immobilize and fixate on a target. Handheld OCT probes have also been demonstrated for successful imaging of pre-term infants and neonates up to ~1 year old. However, no technology yet exists for OCT in young children due to their lack of attention and inherent fear of large objects close to their face. In this work, we demonstrate a prototype retinal swept-source OCT system with a long working distance (from the last optical element to the subject's eye) to facilitate pediatric imaging. To reduce the footprint and weight of the system compared to the conventional 4f scheme, a novel 2f scanning configuration was implemented to achieve a working distance of 348mm with a +/- 8° scanning angle prior to cornea. Employing two custom-designed lenses, the system design resolution was nearly diffraction limited throughout a -8D to +5D refractive corrections. A fixation target displayed on a LCD monitor and an iris camera were used to facilitate alignment and imaging. Our prototype was tested in consented adult subjects and has the potential to facilitate imaging of young children. With this apparatus, young children could potentially sit comfortably in caretaker's lap while viewing entertainment on the fixation screen designed to direct their gaze into the imaging apparatus.

  18. Quantifying the influence of Bessel beams on image quality in optical coherence tomography.

    Science.gov (United States)

    Curatolo, Andrea; Munro, Peter R T; Lorenser, Dirk; Sreekumar, Parvathy; Singe, C Christian; Kennedy, Brendan F; Sampson, David D

    2016-03-24

    Light scattered by turbid tissue is known to degrade optical coherence tomography (OCT) image contrast progressively with depth. Bessel beams have been proposed as an alternative to Gaussian beams to image deeper into turbid tissue. However, studies of turbid tissue comparing the image quality for different beam types are lacking. We present such a study, using numerically simulated beams and experimental OCT images formed by Bessel or Gaussian beams illuminating phantoms with optical properties spanning a range typical of soft tissue. We demonstrate that, for a given scattering parameter, the higher the scattering anisotropy the lower the OCT contrast, regardless of the beam type. When focusing both beams at the same depth in the sample, we show that, at focus and for equal input power and resolution, imaging with the Gaussian beam suffers less reduction of contrast. This suggests that, whilst Bessel beams offer extended depth of field in a single depth scan, for low numerical aperture (NA 0.95), superior contrast (by up to ~40%) may be obtained over an extended depth range by a Gaussian beam combined with dynamic focusing.

  19. Imaging patients with glaucoma using spectral-domain optical coherence tomography and optical microangiography

    Science.gov (United States)

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

    2015-03-01

    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.

  20. Contrast-enhanced optical coherence tomography with picomolar sensitivity for functional in vivo imaging

    Science.gov (United States)

    Liba, Orly; Sorelle, Elliott D.; Sen, Debasish; de La Zerda, Adam

    2016-03-01

    Optical Coherence Tomography (OCT) enables real-time imaging of living tissues at cell-scale resolution over millimeters in three dimensions. Despite these advantages, functional biological studies with OCT have been limited by a lack of exogenous contrast agents that can be distinguished from tissue. Here we report an approach to functional OCT imaging that implements custom algorithms to spectrally identify unique contrast agents: large gold nanorods (LGNRs). LGNRs exhibit 110-fold greater spectral signal per particle than conventional GNRs, which enables detection of individual LGNRs in water and concentrations as low as 250 pM in the circulation of living mice. This translates to ~40 particles per imaging voxel in vivo. Unlike previous implementations of OCT spectral detection, the methods described herein adaptively compensate for depth and processing artifacts on a per sample basis. Collectively, these methods enable high-quality noninvasive contrast-enhanced imaging of OCT in living subjects, including detection of tumor microvasculature at twice the depth achievable with conventional OCT. Additionally, multiplexed detection of spectrally-distinct LGNRs was demonstrated to observe discrete patterns of lymphatic drainage and identify individual lymphangions and lymphatic valve functional states. These capabilities provide a powerful platform for molecular imaging and characterization of tissue noninvasively at cellular resolution, called MOZART.

  1. Characterization of nanowires by coherent X-ray diffractive imaging and ptychography

    Energy Technology Data Exchange (ETDEWEB)

    Dzhigaev, Dmitry

    2017-03-15

    Imaging techniques are of paramount importance for our understanding of the universe. From galaxies and stars explored by huge telescopes down to micro and nanostructures studied by microscopes, imaging systems provide invaluable scientific information. When an object under investigation has a size of about 100 nanometers, X-rays become a perfect probe for non-destructive imaging. The manufacturing process of image forming lenses for X-rays becomes much more complicated comparing to optical ones. Therefore, ''lensless'' techniques which rely on the coherent properties of radiation were developed. With third generation of synchrotron sources highly coherent and intense X-ray beams became widely accessible. They are used in new imaging methods such as coherent X-ray diffractive imaging (CXDI) and X-ray ptychography. Modern nanotechnology opens a wide spectrum of possible applications in different branches of physics, chemistry, biology and engineering. At the nanoscale, matter has different physical and chemical properties compared to the macroscale bulk material. The continuing trend of miniaturization of functional components in semiconductor industry brings new challenges both in growth and characterization methods. This Thesis is focused on application of coherent diffractive imaging methods to reveal the structure of single semiconductor nanowires (NWs). They have been attracting significant attention for a couple of decades due to their efficient strain relaxation properties. And since the strain plays a significant role in NW performance the projects carried out in this work are oriented on Bragg CXDI approaches. Three distinct projects were carried out during my research activity at DESY research center of the Helmholtz Association. Experimental work was performed at P06 and P10 beamlines at PETRA III synchrotron. The first part of this Thesis extends the application of the three-dimensional (3D) Bragg CXDI to strain field mapping in a

  2. Effect of acetic acid on optical coherence tomography (OCT) images of cervical epithelium.

    Science.gov (United States)

    Gallwas, Julia; Stanchi, Anna; Dannecker, Christian; Ditsch, Nina; Mueller, Susanna; Mortensen, Uwe; Stepp, Herbert

    2014-11-01

    Optical coherence tomography (OCT) can be used as an adjunct to colposcopy in the identification of precancerous and cancerous cervical lesions. The purpose of this study was to investigate the effect of acetic acid on OCT imaging. OCT images were taken from unsuspicious and suspicious areas of fresh conization specimens immediately after resection and 3 and 10 min after application of 6 % acetic acid. A corresponding histology was obtained from all sites. The images taken 3 and 10 min after application of acetic acid were compared to the initial images with respect to changes in brightness, contrast, and scanning depth employing a standard nonparametric test of differences of proportions. Further, mean intensity backscattering curves were calculated from all OCT images in the histological groups CIN3, inflammation, or normal epithelium. Mean difference profiles within each of these groups were determined, reflecting the mean differences between the condition before application of acetic acid and the exposure times 3 and 10 min, respectively. According to the null hypothesis, the difference profiles do not differ from profiles fluctuating around zero in a stationary way, which implies that the profiles do not differ significantly from each other. The null hypothesis was tested employing the KPSS test. The visual analysis of 137 OCT images from 46 sites of 10 conization specimens revealed a statistically significant increase in brightness for all three groups and a statistically significant decrease in contrast for normal epithelium after 10 min. Further, an increase in scanning depth was noted for normal epithelium after 10 min and for CIN3 after 3 min. The analysis of mean intensity profiles showed an increased backscattering intensity after application of acetic acid. Acetic acid significantly affects the quality of OCT images. Overall brightness and scanning depth increase with the opposite effect regarding the image contrast. Whether the observed changes

  3. Standardization of choroidal thickness measurements using enhanced depth imaging optical coherence tomography

    Institute of Scientific and Technical Information of China (English)

    Nattapon; Boonarpha; Yalin; Zheng; Alexandros; N.Stangos; Huiqi; Lu; Ankur; Raj; Gabriela; Czanner; Simon; P.Harding; Jayashree; Nair-Sahni

    2015-01-01

    AIM: To describe and evaluate a standardized protocol for measuring the choroidal thickness(Ch T) using enhanced depth imaging optical coherence tomography(EDI OCT).METHODS: Single 9 mm EDI OCT line scans across the fovea were used for this study. The protocol used in this study classified the EDI OCT images into four groups based on the appearance of the choroidal-scleral interface and suprachoroidal space. Two evaluation iterations of experiments were performed: first, the protocol was validated in a pilot study of 12 healthy eyes. Afterwards, the applicability of the protocol was tested in 82 eyes of patients with diabetes. Inter-observer and intra-observer agreements on image classifications were performed using Cohen’s kappa coefficient(κ). Intraclass correlation coefficient(ICC) and Bland-Altman’s methodology were used for the measurement of the Ch T.RESULTS: There was a moderate(κ=0.42) and perfect(κ =1) inter- and intra-observer agreements on image classifications from healthy eyes images and substantial(κ =0.66) and almost perfect(κ =0.86) agreements from diabetic eyes images. The proposed protocol showed excellent inter- and intra-observer agreements for the Ch T measurements on both, healthy eyes and diabetic eyes(ICC >0.90 in all image categories). The Bland-Altman plot showed a relatively large Ch T measurement agreement in the scans that contained less visible choroidal outer boundary. CONCLUSION: A protocol to standardize Ch T measurements in EDI OCT images has been developed;the results obtained using this protocol show that the technique is accurate and reliable for routine clinical practice and research.

  4. Standardization of choroidal thickness measurements using enhanced depth imaging optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Nattapon Boonarpha

    2015-06-01

    Full Text Available AIM:To describe and evaluate a standardized protocol for measuring the choroidal thickness (ChT using enhanced depth imaging optical coherence tomography (EDI OCT.METHODS:Single 9 mm EDI OCT line scans across the fovea were used for this study. The protocol used in this study classified the EDI OCT images into four groups based on the appearance of the choroidal-scleral interface and suprachoroidal space. Two evaluation iterations of experiments were performed:first, the protocol was validated in a pilot study of 12 healthy eyes. Afterwards, the applicability of the protocol was tested in 82 eyes of patients with diabetes. Inter-observer and intra-observer agreements on image classifications were performed using Cohen’s kappa coefficient (k. Intraclass correlation coefficient (ICC and Bland-Altman’s methodology were used for the measurement of the ChT.RESULTS:There was a moderate (k=0.42 and perfect (k=1 inter- and intra-observer agreements on image classifications from healthy eyes images and substantial (k=0.66 and almost perfect (k=0.86 agreements from diabetic eyes images. The proposed protocol showed excellent inter- and intra-observer agreements for the ChT measurements on both, healthy eyes and diabetic eyes (ICC>0.90 in all image categories. The Bland-Altman plot showed a relatively large ChT measurement agreement in the scans that contained less visible choroidal outer boundary.CONCLUSIONS:A protocol to standardize ChT measurements in EDI OCT images has been developed; the results obtained using this protocol show that the technique is accurate and reliable for routine clinical practice and research.

  5. Enhanced depth imaging optical coherence tomography and fundus autofluorescence findings in bilateral choroidal osteoma: a case report

    Directory of Open Access Journals (Sweden)

    Muhammet Kazim Erol

    2013-06-01

    Full Text Available The authors present enhanced depth imaging optical coherence tomography (EDI OCT and fundus autofluorescence (FAF characteristics of a patient with bilateral choroidal osteoma and try to make a correlation between two imaging techniques. Two eyes of a patient with choroidal osteoma underwent complete ophthalmic examination. Enhanced depth imaging optical coherence tomography revealed a cage-like pattern, which corresponded to the calcified region of the tumor. Fundus autofluorescence imaging of the same area showed slight hyperautofluorescence. Three different reflectivity patterns in the decalcified area were defined. In the areas of subretinal fluid, outer segment elongations similar to central serous chorioretinopathy were observed. Hyperautofluorescent spots were evident in fundus autofluorescence in the same area. Calcified and decalcified portions of choroidal osteoma as well as the atrophy of choriocapillaris demonstrated different patterns with enhanced depth imaging and fundus autofluorescence imaging. Both techniques were found to be beneficial in the diagnosis and follow-up of choroidal osteoma.

  6. Enhanced depth imaging optical coherence tomography and fundus autofluorescence findings in bilateral choroidal osteoma: a case report.

    Science.gov (United States)

    Erol, Muhammet Kazim; Coban, Deniz Turgut; Ceran, Basak Bostanci; Bulut, Mehmet

    2013-01-01

    The authors present enhanced depth imaging optical coherence tomography (EDI OCT) and fundus autofluorescence (FAF) characteristics of a patient with bilateral choroidal osteoma and try to make a correlation between two imaging techniques. Two eyes of a patient with choroidal osteoma underwent complete ophthalmic examination. Enhanced depth imaging optical coherence tomography revealed a cage-like pattern, which corresponded to the calcified region of the tumor. Fundus autofluorescence imaging of the same area showed slight hyperautofluorescence. Three different reflectivity patterns in the decalcified area were defined. In the areas of subretinal fluid, outer segment elongations similar to central serous chorioretinopathy were observed. Hyperautofluorescent spots were evident in fundus autofluorescence in the same area. Calcified and decalcified portions of choroidal osteoma as well as the atrophy of choriocapillaris demonstrated different patterns with enhanced depth imaging and fundus autofluorescence imaging. Both techniques were found to be beneficial in the diagnosis and follow-up of choroidal osteoma.

  7. Enhanced depth imaging optical coherence tomography and fundus autofluorescence findings in bilateral choroidal osteoma: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Erol, Muhammet Kazim; Coban, Deniz Turgut; Ceran, Basak Bostanci; Bulut, Mehmet, E-mail: muhammetkazimerol@gmail.com [Kazim Erol. Antalya Training and Research Hospital, Ophthalmology Department, Antalya (Turkey)

    2013-11-01

    The authors present enhanced depth imaging optical coherence tomography (EDI OCT) and fundus autofluorescence (FAF) characteristics of a patient with bilateral choroidal osteoma and try to make a correlation between two imaging techniques. Two eyes of a patient with choroidal osteoma underwent complete ophthalmic examination. Enhanced depth imaging optical coherence tomography revealed a cage-like pattern, which corresponded to the calcified region of the tumor. Fundus autofluorescence imaging of the same area showed slight hyperautofluorescence. Three different reflectivity patterns in the decalcified area were defined. In the areas of subretinal fluid, outer segment elongations similar to central serous chorioretinopathy were observed. Hyperautofluorescent spots were evident in fundus autofluorescence in the same area. Calcified and decalcified portions of choroidal osteoma as well as the atrophy of choriocapillaris demonstrated different patterns with enhanced depth imaging and fundus autofluorescence imaging. Both techniques were found to be beneficial in the diagnosis and follow-up of choroidal osteoma. (author)

  8. Spectral-domain optical coherence tomography staging and autofluorescence imaging in achromatopsia.

    Science.gov (United States)

    Greenberg, Jonathan P; Sherman, Jerome; Zweifel, Sandrine A; Chen, Royce W S; Duncker, Tobias; Kohl, Susanne; Baumann, Britta; Wissinger, Bernd; Yannuzzi, Lawrence A; Tsang, Stephen H

    2014-04-01

    IMPORTANCE Evidence is mounting that achromatopsia is a progressive retinal degeneration, and treatments for this condition are on the horizon. OBJECTIVES To categorize achromatopsia into clinically identifiable stages using spectral-domain optical coherence tomography and to describe fundus autofluorescence imaging in this condition. DESIGN, SETTING, AND PARTICIPANTS A prospective observational study was performed between 2010 and 2012 at the Edward S. Harkness Eye Institute, New York-Presbyterian Hospital. Participants included 17 patients (aged 10-62 years) with full-field electroretinography-confirmed achromatopsia. MAIN OUTCOMES AND MEASURES Spectral-domain optical coherence tomography features and staging system, fundus autofluorescence and near-infrared reflectance features and their correlation to optical coherence tomography, and genetic mutations served as the outcomes and measures. RESULTS Achromatopsia was categorized into 5 stages on spectral-domain optical coherence tomography: stage 1 (2 patients [12%]), intact outer retina; stage 2 (2 patients [12%]), inner segment ellipsoid line disruption; stage 3 (5 patients [29%]), presence of an optically empty space; stage 4 (5 patients [29%]), optically empty space with partial retinal pigment epithelium disruption; and stage 5 (3 patients [18%]), complete retinal pigment epithelium disruption and/or loss of the outer nuclear layer. Stage 1 patients showed isolated hyperreflectivity of the external limiting membrane in the fovea, and the external limiting membrane was hyperreflective above each optically empty space. On near infrared reflectance imaging, the fovea was normal, hyporeflective, or showed both hyporeflective and hyperreflective features. All patients demonstrated autofluorescence abnormalities in the fovea and/or parafovea: 9 participants (53%) had reduced or absent autofluorescence surrounded by increased autofluorescence, 4 individuals (24%) showed only reduced or absent autofluorescence, 3

  9. Three-dimensional imaging of nanoscale materials by using coherent x-rays

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Jianwei

    2011-04-18

    X-ray crystallography is currently the primary methodology used to determine the 3D structure of materials and macromolecules. However, many nanostructures, disordered materials, biomaterials, hybrid materials and biological specimens are noncrystalline and, hence, their structures are not accessible by X-ray crystallography. Probing these structures therefore requires the employment of different approaches. A very promising technique currently under rapid development is X-ray diffraction microscopy (or lensless imaging), in which the coherent X-ray diffraction pattern of a noncrystalline specimen is measured and then directly phased to obtain a high-resolution image. Through the DOE support over the past three years, we have applied X-ray diffraction microscopy to quantitative imaging of GaN quantum dot particles, and revealed the internal GaN-Ga2O3 core shell structure in three dimensions. By exploiting the abrupt change in the scattering cross-section near electronic resonances, we carried out the first experimental demonstration of resonant X-ray diffraction microscopy for element specific imaging. We performed nondestructive and quantitative imaging of buried Bi structures inside a Si crystal by directly phasing coherent X-ray diffraction patterns acquired below and above the Bi M5 edge. We have also applied X-ray diffraction microscopy to nondestructive imaging of mineral crystals inside biological composite materials - intramuscular fish bone - at the nanometer scale resolution. We identified mineral crystals in collagen fibrils at different stages of mineralization and proposed a dynamic mechanism to account for the nucleation and growth of mineral crystals in the collagen matrix. In addition, we have also discovered a novel 3D imaging modality, denoted ankylography, which allows for complete 3D structure determination without the necessity of sample titling or scanning. We showed that when the diffraction pattern of a finite object is sampled at a

  10. A new real-time non-coherent to coherent light image converter - The hybrid field effect liquid crystal light valve

    Science.gov (United States)

    Grinberg, J.; Jacobson, A.; Bleha, W.; Miller, L.; Fraas, L.; Boswell, D.; Myer, G.

    1975-01-01

    A new, high-performance device has been developed for application to real-time coherent optical data processing. The new device embodies a CdS photoconductor, a CdTe light-absorbing layer, a dielectric mirror, and a liquid crystal layer sandwiched between indium-tin-oxide transparent electrodes deposited on optical quality glass flats. The noncoherent image is directed onto the photoconductor; this reduces the impedance of the photoconductor, thereby switching the ac voltage that is impressed across the electrodes onto the liquid crystal to activate the device. The liquid crystal is operated in a hybrid field effect mode. It utilizes the twisted nematic effect to create a dark off-state and the optical birefringence effect to create the bright on-state. The liquid crystal modulates the polarization of the coherent read-out light so an analyzer must be used to create an intensity modulated output beam.

  11. A new real-time non-coherent to coherent light image converter - The hybrid field effect liquid crystal light valve

    Science.gov (United States)

    Grinberg, J.; Jacobson, A.; Bleha, W.; Miller, L.; Fraas, L.; Boswell, D.; Myer, G.

    1975-01-01

    A new, high-performance device has been developed for application to real-time coherent optical data processing. The new device embodies a CdS photoconductor, a CdTe light-absorbing layer, a dielectric mirror, and a liquid crystal layer sandwiched between indium-tin-oxide transparent electrodes deposited on optical quality glass flats. The noncoherent image is directed onto the photoconductor; this reduces the impedance of the photoconductor, thereby switching the ac voltage that is impressed across the electrodes onto the liquid crystal to activate the device. The liquid crystal is operated in a hybrid field effect mode. It utilizes the twisted nematic effect to create a dark off-state and the optical birefringence effect to create the bright on-state. The liquid crystal modulates the polarization of the coherent read-out light so an analyzer must be used to create an intensity modulated output beam.

  12. Imaging internal flows in a drying sessile polymer dispersion drop using Spectral Radar Optical Coherence Tomography (SR-OCT).

    Science.gov (United States)

    Manukyan, Selin; Sauer, Hans M; Roisman, Ilia V; Baldwin, Kyle A; Fairhurst, David J; Liang, Haida; Venzmer, Joachim; Tropea, Cameron

    2013-04-01

    In this work, we present the visualization of the internal flows in a drying sessile polymer dispersion drop on hydrophilic and hydrophobic surfaces with Spectral Radar Optical Coherence Tomography (SR-OCT). We have found that surface features such as the initial contact angle and pinning of the contact line, play a crucial role on the flow direction and final shape of the dried drop. Moreover, imaging through selection of vertical slices using optical coherence tomography offers a feasible alternative compared to imaging through selection of narrow horizontal slices using confocal microscopy for turbid, barely transparent fluids.

  13. Four-dimensional optical coherence tomography imaging of total liquid ventilated rats

    Science.gov (United States)

    Kirsten, Lars; Schnabel, Christian; Gaertner, Maria; Koch, Edmund

    2013-06-01

    Optical coherence tomography (OCT) can be utilized for the spatially and temporally resolved visualization of alveolar tissue and its dynamics in rodent models, which allows the investigation of lung dynamics on the microscopic scale of single alveoli. The findings could provide experimental input data for numerical simulations of lung tissue mechanics and could support the development of protective ventilation strategies. Real four-dimensional OCT imaging permits the acquisition of several OCT stacks within one single ventilation cycle. Thus, the entire four-dimensional information is directly obtained. Compared to conventional virtual four-dimensional OCT imaging, where the image acquisition is extended over many ventilation cycles and is triggered on pressure levels, real four-dimensional OCT is less vulnerable against motion artifacts and non-reproducible movement of the lung tissue over subsequent ventilation cycles, which widely reduces image artifacts. However, OCT imaging of alveolar tissue is affected by refraction and total internal reflection at air-tissue interfaces. Thus, only the first alveolar layer beneath the pleura is visible. To circumvent this effect, total liquid ventilation can be carried out to match the refractive indices of lung tissue and the breathing medium, which improves the visibility of the alveolar structure, the image quality and the penetration depth and provides the real structure of the alveolar tissue. In this study, a combination of four-dimensional OCT imaging with total liquid ventilation allowed the visualization of the alveolar structure in rat lung tissue benefiting from the improved depth range beneath the pleura and from the high spatial and temporal resolution.

  14. Massively parallel data processing for quantitative total flow imaging with optical coherence microscopy and tomography

    Science.gov (United States)

    Sylwestrzak, Marcin; Szlag, Daniel; Marchand, Paul J.; Kumar, Ashwin S.; Lasser, Theo

    2017-08-01

    We present an application of massively parallel processing of quantitative flow measurements data acquired using spectral optical coherence microscopy (SOCM). The need for massive signal processing of these particular datasets has been a major hurdle for many applications based on SOCM. In view of this difficulty, we implemented and adapted quantitative total flow estimation algorithms on graphics processing units (GPU) and achieved a 150 fold reduction in processing time when compared to a former CPU implementation. As SOCM constitutes the microscopy counterpart to spectral optical coherence tomography (SOCT), the developed processing procedure can be applied to both imaging modalities. We present the developed DLL library integrated in MATLAB (with an example) and have included the source code for adaptations and future improvements. Catalogue identifier: AFBT_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AFBT_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPLv3 No. of lines in distributed program, including test data, etc.: 913552 No. of bytes in distributed program, including test data, etc.: 270876249 Distribution format: tar.gz Programming language: CUDA/C, MATLAB. Computer: Intel x64 CPU, GPU supporting CUDA technology. Operating system: 64-bit Windows 7 Professional. Has the code been vectorized or parallelized?: Yes, CPU code has been vectorized in MATLAB, CUDA code has been parallelized. RAM: Dependent on users parameters, typically between several gigabytes and several tens of gigabytes Classification: 6.5, 18. Nature of problem: Speed up of data processing in optical coherence microscopy Solution method: Utilization of GPU for massively parallel data processing Additional comments: Compiled DLL library with source code and documentation, example of utilization (MATLAB script with raw data) Running time: 1,8 s for one B-scan (150 × faster in comparison to the CPU

  15. Coherent diffraction imaging analysis of shape-controlled nanoparticles with focused hard X-ray free-electron laser pulses.

    Science.gov (United States)

    Takahashi, Yukio; Suzuki, Akihiro; Zettsu, Nobuyuki; Oroguchi, Tomotaka; Takayama, Yuki; Sekiguchi, Yuki; Kobayashi, Amane; Yamamoto, Masaki; Nakasako, Masayoshi

    2013-01-01

    We report the first demonstration of the coherent diffraction imaging analysis of nanoparticles using focused hard X-ray free-electron laser pulses, allowing us to analyze the size distribution of particles as well as the electron density projection of individual particles. We measured 1000 single-shot coherent X-ray diffraction patterns of shape-controlled Ag nanocubes and Au/Ag nanoboxes and estimated the edge length from the speckle size of the coherent diffraction patterns. We then reconstructed the two-dimensional electron density projection with sub-10 nm resolution from selected coherent diffraction patterns. This method enables the simultaneous analysis of the size distribution of synthesized nanoparticles and the structures of particles at nanoscale resolution to address correlations between individual structures of components and the statistical properties in heterogeneous systems such as nanoparticles and cells.

  16. Anterior segment spectral domain optical coherence tomography imaging of patients with anterior scleritis.

    Science.gov (United States)

    Levison, Ashleigh L; Lowder, Careen Y; Baynes, Kimberly M; Kaiser, Peter K; Srivastava, Sunil K

    2016-08-01

    The purpose of the study was to describe the findings seen on anterior segment spectral domain optical coherence tomography (SD-OCT) in patients with anterior scleritis and determine the feasibility of using SD-OCT to image and grade the degree of scleral inflammation and monitor response to treatment. All patients underwent slit lamp examination by a uveitis specialist, and the degree of scleral inflammation was recorded. Spectral domain OCT imaging was then performed of the conjunctiva and scleral tissue using a standardized acquisition protocol. The scans were graded and compared to clinical findings. Twenty-eight patients with anterior scleritis and ten patients without ocular disease were included in the study. Seventeen of the scleritis patients were followed longitudinally. Common findings on SD-OCT in patients with active scleritis included changes in hyporeflectivity within the sclera, nodules, and visible vessels within the sclera. There was significant variation in findings on SD-OCT within each clinical grade of active scleritis. These changes on SD-OCT improved with treatment and clinical improvement. SD-OCT imaging provided various objective measures that could be used in the future to grade inflammatory activity in patients with anterior scleritis. Longitudinal imaging of patients with active scleritis demonstrated that SD-OCT may have great utility in monitoring response to treatment.

  17. Gold Nanoprobe-Enabled Three-Dimensional Ozone Imaging by Optical Coherence Tomography.

    Science.gov (United States)

    Jiang, Xueqin; Tang, Peijun; Gao, Panpan; Zhang, Yu Shrike; Yi, Changqing; Zhou, Jianhua

    2017-02-21

    Ozone (O3) would be harmful to human skin for its strong oxidizing property, especially when stratum corneum or corneal epithelium is wounded. Imaging the penetration and distribution of ozone at depth is beneficial for studying the influence of ozone on skin or eyes. Here, we introduced a facile method for three-dimensional (3D) imaging of the penetration of O3 into the anterior chamber of an isolated crucian carp eye by using optical coherence tomography (OCT) combined with gold triangular nanoprisms (GTNPs) as the contrast agent and molecular probe. We illustrated the specific response of GTNPs to ozone and demonstrated that GTNPs can function as an efficient nanoprobe for sensing O3. The stabilities of GTNPs in different biologic solutions, as well as the signal intensity of GTNPs on an OCT imaging system, were investigated. Visualization of 3D penetration and distribution of O3 in the biologic tissue was proved for the first time. The quantitative analysis of O3 diffusion in the anterior chamber of the fish eye revealed a penetration depth of 311 μm within 172 min. Due to the strong scattering, near-infrared extinction band, and easy functionalization of GTNPs, they could further serve as nanoprobes for 3D OCT or multimodal imaging of other molecules or ions in the future.

  18. Using optical coherence tomography (OCT) imaging in the evaluation of airway dynamics (Conference Presentation)

    Science.gov (United States)

    Szabari, Margit V.; Kelly, Vanessa J.; Applegate, Matthew B.; Chee, Chunmin; Tan, Khay M.; Hariri, Lida P.; Harris, R. Scott; Winkler, Tilo; Suter, Melissa J.

    2016-03-01

    Asthma is a chronic disease resulting in periodic attacks of coughing and wheezing due to temporarily constricted and clogged airways. The pathophysiology of asthma and the process of airway narrowing are not completely understood. Appropriate in vivo imaging modality with sufficient spatial and temporal resolution to dynamically assess the behavior of airways is missing. Optical coherence tomography (OCT) enables real-time evaluation of the airways during dynamic and static breathing maneuvers. Our aim was to visualize the structure and function of airways in healthy and Methacholine (MCh) challenged lung. Sheep (n=3) were anesthetized, mechanically ventilated and imaged with OCT in 4 dependent and 4 independent airways both pre- and post-MCh administration. The OCT system employed a 2.4 Fr (0.8 mm diameter) catheter and acquired circumferential cross-sectional images in excess of 100 frames per second during dynamic tidal breathing, 20 second static breath-holds at end-inspiration and expiration pressure, and in a response to a single deep inhalation. Markedly different airway behavior was found in dependent versus non-dependent airway segments before and after MCh injection. OCT is a non-ionizing light-based imaging modality, which may provide valuable insight into the complex dynamic behavior of airway structure and function in the normal and asthmatic lung.

  19. Clutter noise reduction for phased array imaging using frequency-spatial polarity coherence

    Science.gov (United States)

    Gongzhang, Rui; Gachagan, Anthony; Xiao, Bo

    2015-03-01

    A number of materials used in industry exhibit highly-scattering properties which can reduce the performance of conventional ultrasonic NDE approaches. Moving Bandwidth Polarity Thresholding (MBPT) is a robust frequency diversity based algorithm for scatter noise reduction in single A-scan waveforms, using sign coherence across a range of frequency bands to reduce grain noise and improve Signal to Noise Ratio. Importantly, for this approach to be extended to array applications, spatial variation of noise characteristics must also be considered. This paper presents a new spatial-frequency diversity based algorithm for array imaging, extended from MBPT. Each A-scan in the full matrix capture array dataset is partitioned into a serial of overlapped frequency bands and then undergoes polarity thresholding to generate sign-only coefficients indicating possible flaw locations within each selected band. These coefficients are synthesized to form a coefficient matrix using a delay and sum approach in each frequency band. Matrices produced across the frequency bands are then summed to generate a weighting matrix, which can be applied on any conventional image. A 5MHz linear array has been used to acquire data from both austenitic steel and high nickel alloy (HNA) samples to validate the proposed algorithm. Background noise is significantly suppressed for both samples after applying this approach. Importantly, three side drilled holes and the back wall of the HNA sample are clearly enhanced in the processed image, with a mean 133% Contrast to Noise Ratio improvement when compared to a conventional TFM image.

  20. Imaging of non tumorous and tumorous human brain tissue with full-field optical coherence tomography

    CERN Document Server

    Assayag, Osnath; Devaux, Bertrand; Harms, Fabrice; Pallud, Johan; Chretien, Fabrice; Boccara, Claude; Varlet, Pascale

    2013-01-01

    A prospective study was performed on neurosurgical samples from 18 patients to evaluate the use of Full-Field Optical Coherence Tomography (FF-OCT) in brain tumor diagnosis. FF-OCT captures en face slices of tissue samples at 1\\mum resolution in 3D with a typical 200\\mum imaging depth. A 1cm2 specimen is scanned at a single depth and processed in about 5 minutes. This rapid imaging process is non-invasive and 30 requires neither contrast agent injection nor tissue preparation, which makes it particularly well suited to medical imaging applications. Temporal chronic epileptic parenchyma and brain tumors such as meningiomas, low- grade and high-grade gliomas, and choroid plexus papilloma were imaged. A subpopulation of neurons, myelin fibers and CNS vasculature were clearly identified. Cortex could be discriminated from white matter, but individual glial cells as astrocytes (normal or reactive) or oligodendrocytes were not observable. This study reports for the first time on the feasibility of using FF-OCT in a...

  1. Three-dimensional coherent X-ray diffractive imaging of whole frozen-hydrated cells

    Directory of Open Access Journals (Sweden)

    Jose A. Rodriguez

    2015-09-01

    Full Text Available A structural understanding of whole cells in three dimensions at high spatial resolution remains a significant challenge and, in the case of X-rays, has been limited by radiation damage. By alleviating this limitation, cryogenic coherent diffractive imaging (cryo-CDI can in principle be used to bridge the important resolution gap between optical and electron microscopy in bio-imaging. Here, the first experimental demonstration of cryo-CDI for quantitative three-dimensional imaging of whole frozen-hydrated cells using 8 keV X-rays is reported. As a proof of principle, a tilt series of 72 diffraction patterns was collected from a frozen-hydrated Neospora caninum cell and the three-dimensional mass density of the cell was reconstructed and quantified based on its natural contrast. This three-dimensional reconstruction reveals the surface and internal morphology of the cell, including its complex polarized sub-cellular structure. It is believed that this work represents an experimental milestone towards routine quantitative three-dimensional imaging of whole cells in their natural state with spatial resolutions in the tens of nanometres.

  2. Flat Choroidal Nevus Inaccessible to Ultrasound Sonography Evaluated by Enhanced Depth Imaging Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Chrysanthi Basdekidou

    2011-06-01

    Full Text Available Purpose: To demonstrate the usefulness of enhanced depth imaging optical coherence tomography (EDI-OCT in investigating choroidal lesions inaccessible to ultrasound sonography. Methods: In a 60-year-old woman with an asymptomatic choroidal nevus, normal OCT was used to observe the macula and EDI-OCT to image the choroidal nevus that was inaccessible to ultrasound. The exact location of the lesion in the choroid and the dimensions of the nevus were measured. Results: The lesion was located in the superior macula, and the nevus was homogeneous in its reflectivity. We observed a thickened choroid delineated by the shadow cone behind it, measuring 1,376 × 325 µm in the larger vertical cut and 1,220 × 325 µm in the larger horizontal cut in an image with a 1:1 pixel mapping and automatic zoom. The macular profile and thickness were both normal. Conclusions: EDI-OCT appears to be an excellent technique for measuring choroidal nevi and all choroidal lesions accessible to OCT imaging by depicting their exact location in the choroid, their dimensions, and their demarcation from the surrounding healthy tissue, thus allowing for a more efficient and accurate follow-up.

  3. Improved Imaging of Magnetically Labeled Cells Using Rotational Magnetomotive Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Peter Cimalla

    2017-04-01

    Full Text Available In this paper, we present a reliable and robust method for magnetomotive optical coherence tomography (MM-OCT imaging of single cells labeled with iron oxide particles. This method employs modulated longitudinal and transverse magnetic fields to evoke alignment and rotation of anisotropic magnetic structures in the sample volume. Experimental evidence suggests that magnetic particles assemble themselves in elongated chains when exposed to a permanent magnetic field. Magnetomotion in the intracellular space was detected and visualized by means of 3D OCT as well as laser speckle reflectometry as a 2D reference imaging method. Our experiments on mesenchymal stem cells embedded in agar scaffolds show that the magnetomotive signal in rotational MM-OCT is significantly increased by a factor of ~3 compared to previous pulsed MM-OCT, although the solenoid’s power consumption was 16 times lower. Finally, we use our novel method to image ARPE-19 cells, a human retinal pigment epithelium cell line. Our results permit magnetomotive imaging with higher sensitivity and the use of low power magnetic fields or larger working distances for future three-dimensional cell tracking in target tissues and organs.

  4. Investigation of alterations in multifractality in optical coherence tomographic images of in vivo human retina

    Science.gov (United States)

    Das, Nandan Kumar; Mukhopadhyay, Sabyasachi; Ghosh, Nirmalya; Chhablani, Jay; Richhariya, Ashutosh; Divakar Rao, Kompalli; Sahoo, Naba Kishore

    2016-09-01

    Optical coherence tomography (OCT) enables us to monitor alterations in the thickness of the retinal layer as disease progresses in the human retina. However, subtle morphological changes in the retinal layers due to early disease progression often may not lead to detectable alterations in the thickness. OCT images encode depth-dependent backscattered intensity distribution arising due to the depth distributions of the refractive index from tissue microstructures. Here, such depth-resolved refractive index variations of different retinal layers were analyzed using multifractal detrended fluctuation analysis, a special class of multiresolution analysis tools. The analysis extracted and quantified microstructural multifractal information encoded in normal as well as diseased human retinal OCT images acquired in vivo. Interestingly, different layers of the retina exhibited different degrees of multifractality in a particular retina, and the individual layers displayed consistent multifractal trends in healthy retinas of different human subjects. In the retinal layers of diabetic macular edema (DME) subjects, the change in multifractality manifested prominently near the boundary of the DME as compared to the normal retinal layers. The demonstrated ability to quantify depth-resolved information on multifractality encoded in OCT images appears promising for the early diagnosis of diseases of the human eye, which may also prove useful for detecting other types of tissue abnormalities from OCT images.

  5. Optical imaging of oral pathological tissue using optical coherence tomography and synchrotron radiation computed microtomography

    Science.gov (United States)

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

    2013-06-01

    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.

  6. Validating Intravascular Imaging with Serial Optical Coherence Tomography and Confocal Fluorescence Microscopy

    Science.gov (United States)

    Tardif, Pier-Luc; Bertrand, Marie-Jeanne; Abran, Maxime; Castonguay, Alexandre; Lefebvre, Joël; Stähli, Barbara E.; Merlet, Nolwenn; Mihalache-Avram, Teodora; Geoffroy, Pascale; Mecteau, Mélanie; Busseuil, David; Ni, Feng; Abulrob, Abedelnasser; Rhéaume, Éric; L’Allier, Philippe; Tardif, Jean-Claude; Lesage, Frédéric

    2016-01-01

    Atherosclerotic cardiovascular diseases are characterized by the formation of a plaque in the arterial wall. Intravascular ultrasound (IVUS) provides high-resolution images allowing delineation of atherosclerotic plaques. When combined with near infrared fluorescence (NIRF), the plaque can also be studied at a molecular level with a large variety of biomarkers. In this work, we present a system enabling automated volumetric histology imaging of excised aortas that can spatially correlate results with combined IVUS/NIRF imaging of lipid-rich atheroma in cholesterol-fed rabbits. Pullbacks in the rabbit aortas were performed with a dual modality IVUS/NIRF catheter developed by our group. Ex vivo three-dimensional (3D) histology was performed combining optical coherence tomography (OCT) and confocal fluorescence microscopy, providing high-resolution anatomical and molecular information, respectively, to validate in vivo findings. The microscope was combined with a serial slicer allowing for the imaging of the whole vessel automatically. Colocalization of in vivo and ex vivo results is demonstrated. Slices can then be recovered to be tested in conventional histology. PMID:27983695

  7. Validating Intravascular Imaging with Serial Optical Coherence Tomography and Confocal Fluorescence Microscopy

    Directory of Open Access Journals (Sweden)

    Pier-Luc Tardif

    2016-12-01

    Full Text Available Atherosclerotic cardiovascular diseases are characterized by the formation of a plaque in the arterial wall. Intravascular ultrasound (IVUS provides high-resolution images allowing delineation of atherosclerotic plaques. When combined with near infrared fluorescence (NIRF, the plaque can also be studied at a molecular level with a large variety of biomarkers. In this work, we present a system enabling automated volumetric histology imaging of excised aortas that can spatially correlate results with combined IVUS/NIRF imaging of lipid-rich atheroma in cholesterol-fed rabbits. Pullbacks in the rabbit aortas were performed with a dual modality IVUS/NIRF catheter developed by our group. Ex vivo three-dimensional (3D histology was performed combining optical coherence tomography (OCT and confocal fluorescence microscopy, providing high-resolution anatomical and molecular information, respectively, to validate in vivo findings. The microscope was combined with a serial slicer allowing for the imaging of the whole vessel automatically. Colocalization of in vivo and ex vivo results is demonstrated. Slices can then be recovered to be tested in conventional histology.

  8. Optical coherence tomography using images of hair structure and dyes penetrating into the hair.

    Science.gov (United States)

    Tsugita, Tetsuya; Iwai, Toshiaki

    2014-11-01

    Hair dyes are commonly evaluated by the appearance of the hair after dyeing. However, this approach cannot simultaneously assess how deep the dye has penetrated into hair. For simultaneous assessment of the appearance and the interior of hair, we developed a visible-range red, green, and blue (RGB) (three primary colors)-optical coherence tomography (OCT) using an RGB LED light source. We then evaluated a phantom model based on the assumption that the sample's absorbability in the vertical direction affects the tomographic imaging. Consistent with theory, our device showed higher resolution than conventional OCT with far-red light. In the experiment on the phantom model, we confirmed that the tomographic imaging is affected by absorbability unique to the sample. Furthermore, we verified that permeability can be estimated from this tomographic image. We also identified for the first time the relationship between penetration of the dye into hair and characteristics of wavelength by tomographic imaging of dyed hair. We successfully simultaneously assessed the appearance of dyed hair and inward penetration of the dye without preparing hair sections. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. Enhanced Depth Imaging Optical Coherence Tomography: A New Way Measuring Choroidal Thickness in Pregnant Women

    Directory of Open Access Journals (Sweden)

    Jun Zhang

    2017-01-01

    Full Text Available The body changes markedly during pregnancy; each system behaves differently from a nonpregnant state. As the eyes are the only windows to see directly what is going on in the internal environment, more and more researches have been done to explain the association between ocular changes and the physiological and pathological changes during pregnancy. The choroid is one of the critical parts of the eye, providing nutrition. And abnormal choroid may result in ocular dysfunction and visual problems. As the optical coherence tomography develops, a rapid, direct, noninvasive, and nontoxic way is available to obtain the choroid situation of pregnant women, which may explain the mechanism of pregnancy-related eye diseases. This review would summarize relevant original articles published from January 1, 2008 to December 1, 2016 to assess the changes of choroidal thickness (CT with enhanced depth imaging optical coherence tomography (EDI-OCT during pregnancy. And the relationship between choroidal thickness changes and pregnancy remains uncertain. To our knowledge, this is the first review of EDI-OCT in assessing the choroidal thickness of the pregnant women.

  10. Enhanced Depth Imaging Optical Coherence Tomography: A New Way Measuring Choroidal Thickness in Pregnant Women

    Science.gov (United States)

    2017-01-01

    The body changes markedly during pregnancy; each system behaves differently from a nonpregnant state. As the eyes are the only windows to see directly what is going on in the internal environment, more and more researches have been done to explain the association between ocular changes and the physiological and pathological changes during pregnancy. The choroid is one of the critical parts of the eye, providing nutrition. And abnormal choroid may result in ocular dysfunction and visual problems. As the optical coherence tomography develops, a rapid, direct, noninvasive, and nontoxic way is available to obtain the choroid situation of pregnant women, which may explain the mechanism of pregnancy-related eye diseases. This review would summarize relevant original articles published from January 1, 2008 to December 1, 2016 to assess the changes of choroidal thickness (CT) with enhanced depth imaging optical coherence tomography (EDI-OCT) during pregnancy. And the relationship between choroidal thickness changes and pregnancy remains uncertain. To our knowledge, this is the first review of EDI-OCT in assessing the choroidal thickness of the pregnant women. PMID:28630765

  11. Enhanced Depth Imaging Optical Coherence Tomography: A New Way Measuring Choroidal Thickness in Pregnant Women.

    Science.gov (United States)

    Zhang, Jun; Wang, Huiyun; Yu, Qiubo; Tong, Qihu; Lu, Qinkang

    2017-01-01

    The body changes markedly during pregnancy; each system behaves differently from a nonpregnant state. As the eyes are the only windows to see directly what is going on in the internal environment, more and more researches have been done to explain the association between ocular changes and the physiological and pathological changes during pregnancy. The choroid is one of the critical parts of the eye, providing nutrition. And abnormal choroid may result in ocular dysfunction and visual problems. As the optical coherence tomography develops, a rapid, direct, noninvasive, and nontoxic way is available to obtain the choroid situation of pregnant women, which may explain the mechanism of pregnancy-related eye diseases. This review would summarize relevant original articles published from January 1, 2008 to December 1, 2016 to assess the changes of choroidal thickness (CT) with enhanced depth imaging optical coherence tomography (EDI-OCT) during pregnancy. And the relationship between choroidal thickness changes and pregnancy remains uncertain. To our knowledge, this is the first review of EDI-OCT in assessing the choroidal thickness of the pregnant women.

  12. Parabolic single-crystal diamond compound refractive lenses for coherent x-ray imaging (Conference Presentation)

    Science.gov (United States)

    Terentyev, Sergey; Blank, Vladimir D.; Polyakov, Sergey; Zholudev, Sergey; Snigirev, Anatoly A.; Polikarpov, Maxim; Kolodziej, Tomasz; Qian, Jun; Zhou, Hua; Shvyd'ko, Yuri V.

    2016-09-01

    We demonstrate parabolic single-crystal diamond compound refractive lenses [1] designed for coherent x-ray imaging resilient to extreme thermal and radiation loading expected from next generation light sources. To ensure the preservation of coherence and resilience, the lenses are manufactured from the highest-quality single-crystalline synthetic diamond material grown by a high-pressure high-temperature technique. Picosecond laser milling is applied to machine lenses to parabolic shapes with a 1-micron precision and surface roughness. A compound refractive lens comprised of six lenses with a radius of curvature R=200 microns at the vertex of the parabola and a geometrical aperture A=900 microns focuses 10 keV x-ray photons from an undulator source at the Advanced Photon Source facility to a focal spot size of 10x40 microns^2 with a gain factor of 100. [1] S. Terentyev, V. Blank, S. Polyakov, S. Zholudev, A. Snigirev, M. Polikarpov, T. Kolodziej, J. Qian, H. Zhou, and Yu. Shvyd'ko Applied Physics Letters 107, 111108 (2015); doi: 10.1063/1.4931357

  13. Corrections and improvements of lung imaging under Optical Coherence Tomography (OCT)

    Science.gov (United States)

    Golabchi, Ali

    Visualization and correct assessment of alveolar volume via intact lung imaging is important to study and assess respiratory mechanics. Optical Coherence Tomography (OCT), a real time imaging technique based on near-infrared interferometry, can image several layers of distal alveoli in intact, ex-vivo lung tissue. However optical effects associated with heterogeneity of lung tissue, including the refraction caused by air-tissue interfaces along alveoli and duct walls, and changes in speed of light as it travels through the tissue, result in inaccurate measurement of alveolar volume. Experimentally such errors have been difficult to analyze because of lack of ''ground truth,'' as the lung has a unique microstructure of liquid-coated thin walls surrounding relatively large airspaces, which is difficult to model with synthetic foams. In addition, both lung and foams contain airspaces of highly irregular shape, further complicating quantitative measurement of optical artifacts and correction. To address this we have adapted the Bragg-Nye bubble raft, a crystalline two-dimensional arrangement of elements similar in geometry to alveoli (up to several hundred um in diameter with thin walls) as an inflated lung phantom in order to understand, analyze and correct these errors. By applying exact optical ray tracing on OCT images of the bubble raft, the errors are predicted and corrected. The results are validated by imaging the bubble raft with OCT from one edge and with a charged coupled device (CCD) camera in transillumination from top, providing ground truth for the OCT. We also developed a tomographic technique based on incoherent summation of multiple angle-diverse images by utilizing image registration to increase our depth of imaging and our results were validated by utilizing the inflated lung phantom. In this thesis also, an experimental apparatus for macro-scale mechanical probing of lung with in-situ micro-scale imaging of alveolar deformation was analyzed

  14. Possibility of single biomolecule imaging with coherent amplification of weak scattering x-ray photons.

    Science.gov (United States)

    Shintake, Tsumoru

    2008-10-01

    The number of photons produced by coherent x-ray scattering from a single biomolecule is very small because of its extremely small elastic-scattering cross section and low damage threshold. Even with a high x-ray flux of 3 x 10;{12} photons per 100-nm -diameter spot and an ultrashort pulse of 10 fs driven by a future x-ray free electron laser (x-ray FEL), it has been predicted that only a few 100 photons will be produced from the scattering of a single lysozyme molecule. In observations of scattered x rays on a detector, the transfer of energy from wave to matter is accompanied by the quantization of the photon energy. Unfortunately, x rays have a high photon energy of 12 keV at wavelengths of 1A , which is required for atomic resolution imaging. Therefore, the number of photoionization events is small, which limits the resolution of imaging of a single biomolecule. In this paper, I propose a method: instead of directly observing the photons scattered from the sample, we amplify the scattered waves by superimposing an intense coherent reference pump wave on it and record the resulting interference pattern on a planar x-ray detector. Using a nanosized gold particle as a reference pump wave source, we can collect 10;{4}-10;{5} photons in single shot imaging where the signal from a single biomolecule is amplified and recorded as two-dimensional diffraction intensity data. An iterative phase retrieval technique can be used to recover the phase information and reconstruct the image of the single biomolecule and the gold particle at the same time. In order to precisely reconstruct a faint image of the single biomolecule in Angstrom resolution, whose intensity is much lower than that of the bright gold particle, I propose a technique that combines iterative phase retrieval on the reference pump wave and the digital Fourier transform holography on the sample. By using a large number of holography data, the three-dimensional electron density map can be assembled.

  15. Pulse wave imaging using coherent compounding in a phantom and in vivo

    Science.gov (United States)

    Zacharias Apostolakis, Iason; McGarry, Matthew D. J.; Bunting, Ethan A.; Konofagou, Elisa E.

    2017-03-01

    Pulse wave velocity (PWV) is a surrogate marker of arterial stiffness linked to cardiovascular morbidity. Pulse wave imaging (PWI) is a technique developed by our group for imaging the pulse wave propagation in vivo. PWI requires high temporal and spatial resolution, which conventional ultrasonic imaging is unable to simultaneously provide. Coherent compounding is known to address this tradeoff and provides full aperture images at high frame rates. This study aims to implement PWI using coherent compounding within a GPU-accelerated framework. The results of the implemented method were validated using a silicone phantom against static mechanical testing. Reproducibility of the measured PWVs was assessed in the right common carotid of six healthy subjects (n  =  6) approximately 10–15 mm before the bifurcation during two cardiac cycles over the course of 1–3 d. Good agreement of the measured PWVs (3.97  ±  1.21 m s‑1, 4.08  ±  1.15 m s‑1, p  =  0.74) was obtained. The effects of frame rate, transmission angle and number of compounded plane waves on PWI performance were investigated in the six healthy volunteers. Performance metrics such as the reproducibility of the PWVs, the coefficient of determination (r 2), the SNR of the PWI axial wall velocities (\\text{SN}{{\\text{R}}{{\\text{v}_{\\text{PWI}}}}} ) and the percentage of lateral positions where the pulse wave appears to arrive at the same time-point, indicating inadequacy of the temporal resolution (i.e. temporal resolution misses) were used to evaluate the effect of each parameter. Compounding plane waves transmitted at 1° increments with a linear array yielded optimal performance, generating significantly higher r 2 and \\text{SN}{{\\text{R}}{{\\text{v}_{\\text{PWI}}}}} values (p  ⩽  0.05). Higher frame rates (⩾1667 Hz) produced improvements with significant gains in the r 2 coefficient (p  ⩽  0.05) and significant increase in both r 2 and

  16. Imaging and Elastometry of Blood Clots Using Magnetomotive Optical Coherence Tomography and Labeled Platelets

    Science.gov (United States)

    Oldenburg, Amy L.; Wu, Gongting; Spivak, Dmitry; Tsui, Frank; Wolberg, Alisa S.; Fischer, Thomas H.

    2013-01-01

    Improved methods for imaging and assessment of vascular defects are needed for directing treatment of cardiovascular pathologies. In this paper, we employ magnetomotive optical coherence tomography (MMOCT) as a platform both to detect and to measure the elasticity of blood clots. Detection is enabled through the use of rehydrated, lyophilized platelets loaded with superparamagnetic iron oxides (SPIO-RL platelets) that are functional infusion agents that adhere to sites of vascular endothelial damage. Evidence suggests that the sensitivity for detection is improved over threefold by magnetic interactions between SPIOs inside RL platelets. Using the same MMOCT system, we show how elastometry of simulated clots, using resonant acoustic spectroscopy, is correlated with the fibrin content of the clot. Both methods are based upon magnetic actuation and phase-sensitive optical monitoring of nanoscale displacements using MMOCT, underscoring its utility as a broad-based platform to detect and measure the molecular structure and composition of blood clots. PMID:23833549

  17. A comparison of two methods to measure choroidal thickness by enhanced depth imaging optical coherence tomography

    DEFF Research Database (Denmark)

    Lundberg, Lars Kristian; Vestergaard, Anders Højslet; Vergmann, Anna Stage

    coherence tomography (EDI-SD OCT) has made it possible to visualize the choroid, and it is generally accepted that Heidelberg Spectralis OCT provides valid measurements of choroidal thickness (CT), although no fully automated software is commercially available. Two methods for CT-measurement are available...... the CT: 1: Segmentation method; by the use of the thickness profile window we manually edited and moved the inner limiting membrane (ILM) line to the choroid-scleral border (CSB), while we kept the automated defined Bruchs membrane (BM). Hereafter, the software calculated the vertical distance between......Introduction The choroid is believed to be involved in the pathophysiology of several vision threatening diseases such as age-related macular degeneration, central serous chorioretinopathy, inflammatory disorders and myopic macular degeneration. Enhanced depth imaging spectral-domain optical...

  18. Microscope-integrated optical coherence tomography for image-aided positioning of glaucoma surgery

    Science.gov (United States)

    Li, Xiqi; Wei, Ling; Dong, Xuechuan; Huang, Ping; Zhang, Chun; He, Yi; Shi, Guohua; Zhang, Yudong

    2015-07-01

    Most glaucoma surgeries involve creating new aqueous outflow pathways with the use of a small surgical instrument. This article reported a microscope-integrated, real-time, high-speed, swept-source optical coherence tomography system (SS-OCT) with a 1310-nm light source for glaucoma surgery. A special mechanism was designed to produce an adjustable system suitable for use in surgery. A two-graphic processing unit architecture was used to speed up the data processing and real-time volumetric rendering. The position of the surgical instrument can be monitored and measured using the microscope and a grid-inserted image of the SS-OCT. Finally, experiments were simulated to assess the effectiveness of this integrated system. Experimental results show that this system is a suitable positioning tool for glaucoma surgery.

  19. Investigation of horizontal structures at mesospheric altitudes using coherent radar imaging

    Science.gov (United States)

    Sommer, S.; Stober, G.; Schult, C.; Zecha, M.; Latteck, R.

    2013-07-01

    The Middle Atmosphere Alomar Radar System (MAARSY) in Northern Norway (69.30°N, 16.04°E) was used to perform interferometric observations of Polar Mesosperic Summer Echoes (PMSE) in June 2012. Coherent Radar Imaging (CRI) using Capon's method was applied allowing a high spatial resolution. The algorithm was validated by simulation and trajectories of meteor head echoes. Both data sets show a good correspondence with the algorithm. Using this algorithm, the aspect sensitivity of PMSE was analysed in a case study, making use of the capability of CRI to resolve the pattern within the beam volume. No correction of the beam pattern was made yet. It was found in this case study, that no large variations in the scattering width and the scattering center occured apart from a very short period of time at the upper edge of the PMSE.

  20. Development of an adaptable coherent x-ray diffraction microscope with the emphasis on imaging hydrated specimens

    Science.gov (United States)

    Nam, Daewoong; Park, Jaehyun; Gallagher-Jones, Marcus; Shimada, Hiroki; Kim, Sangsoo; Kim, Sunam; Kohmura, Yoshiki; Ishikawa, Tetsuya; Song, Changyong

    2013-11-01

    This paper describes the development of a versatile coherent x-ray diffraction microscope capable of imaging biological specimens in solution. The microscope is a flexible platform accommodating various conditions, from low vacuum (10-2 Pa) to helium gas filled ambient pressure. This flexibility greatly expands the application area, from in situ materials science to biology systems in their native state, by significantly relaxing restrictions to the sample environment. The coherent diffraction microscope has been used successfully to image a yeast cell immersed in buffer solution. We believe that the design of this coherent diffraction microscope can be directly adapted to various platforms such as table top soft x-ray laser, synchrotron x-ray sources, and x-ray free electron laser with minor relevant adjustments.

  1. Design of the mirror optical systems for coherent diffractive imaging at the SPB/SFX instrument of the European XFEL

    Science.gov (United States)

    Bean, Richard J.; Aquila, Andrew; Samoylova, Liubov; Mancuso, Adrian P.

    2016-07-01

    The high degree of spatial coherence and extreme pulse energies available at x-ray free electron laser (XFEL) sources naturally support coherent diffractive imaging applications. In order to optimally exploit these unique properties, the optical systems at XFELs must be highly transmissive, focus to appropriate sizes matched to the scale of samples to be investigated and must minimally perturb the wavefront of the XFEL beam. We present the design and simulated performance of two state-of-the-art Kirkpatrik-Baez mirror systems that form the primary foci of the single particles, clusters and biomolecules and serial femtosecond crystallography (SPB/SFX) instrument of the European XFEL. The two systems, presently under construction, will produce 1 μm and 100 nm scale foci across a 3-16 keV photon energy range. Targeted applications include coherent imaging of weakly scattering, often biological, specimens.

  2. Offline fusion of co-registered intravascular ultrasound and frequency domain optical coherence tomography images for the analysis of human atherosclerotic plaques

    DEFF Research Database (Denmark)

    Räber, Lorenz; Heo, Jung Ho; Radu, Maria D

    2012-01-01

    To demonstrate the feasibility and potential usefulness of an offline fusion of matched optical coherence tomography (OCT) and intravascular ultrasound (IVUS)/virtual histology (IVUS-VH) images.......To demonstrate the feasibility and potential usefulness of an offline fusion of matched optical coherence tomography (OCT) and intravascular ultrasound (IVUS)/virtual histology (IVUS-VH) images....

  3. Morphological image analysis for classification of gastrointestinal tissues using optical coherence tomography

    Science.gov (United States)

    Garcia-Allende, P. Beatriz; Amygdalos, Iakovos; Dhanapala, Hiruni; Goldin, Robert D.; Hanna, George B.; Elson, Daniel S.

    2012-01-01

    Computer-aided diagnosis of ophthalmic diseases using optical coherence tomography (OCT) relies on the extraction of thickness and size measures from the OCT images, but such defined layers are usually not observed in emerging OCT applications aimed at "optical biopsy" such as pulmonology or gastroenterology. Mathematical methods such as Principal Component Analysis (PCA) or textural analyses including both spatial textural analysis derived from the two-dimensional discrete Fourier transform (DFT) and statistical texture analysis obtained independently from center-symmetric auto-correlation (CSAC) and spatial grey-level dependency matrices (SGLDM), as well as, quantitative measurements of the attenuation coefficient have been previously proposed to overcome this problem. We recently proposed an alternative approach consisting of a region segmentation according to the intensity variation along the vertical axis and a pure statistical technology for feature quantification. OCT images were first segmented in the axial direction in an automated manner according to intensity. Afterwards, a morphological analysis of the segmented OCT images was employed for quantifying the features that served for tissue classification. In this study, a PCA processing of the extracted features is accomplished to combine their discriminative power in a lower number of dimensions. Ready discrimination of gastrointestinal surgical specimens is attained demonstrating that the approach further surpasses the algorithms previously reported and is feasible for tissue classification in the clinical setting.

  4. Classification of coronary artery tissues using optical coherence tomography imaging in Kawasaki disease

    Science.gov (United States)

    Abdolmanafi, Atefeh; Prasad, Arpan Suravi; Duong, Luc; Dahdah, Nagib

    2016-03-01

    Intravascular imaging modalities, such as Optical Coherence Tomography (OCT) allow nowadays improving diagnosis, treatment, follow-up, and even prevention of coronary artery disease in the adult. OCT has been recently used in children following Kawasaki disease (KD), the most prevalent acquired coronary artery disease during childhood with devastating complications. The assessment of coronary artery layers with OCT and early detection of coronary sequelae secondary to KD is a promising tool for preventing myocardial infarction in this population. More importantly, OCT is promising for tissue quantification of the inner vessel wall, including neo intima luminal myofibroblast proliferation, calcification, and fibrous scar deposits. The goal of this study is to classify the coronary artery layers of OCT imaging obtained from a series of KD patients. Our approach is focused on developing a robust Random Forest classifier built on the idea of randomly selecting a subset of features at each node and based on second- and higher-order statistical texture analysis which estimates the gray-level spatial distribution of images by specifying the local features of each pixel and extracting the statistics from their distribution. The average classification accuracy for intima and media are 76.36% and 73.72% respectively. Random forest classifier with texture analysis promises for classification of coronary artery tissue.

  5. High-definition optical coherence tomography imaging for noninvasive examination of heritage works.

    Science.gov (United States)

    Zaki, Farzana; Hou, Isabella; Cooper, Denver; Patel, Divya; Yang, Yi; Liu, Xuan

    2016-12-20

    Cultural heritage works, such as ancient murals and historical paintings, are examined routinely for the purpose of conservation. Previous works have applied optical coherence tomography (OCT), which is a three-dimensional (3D) microscopic imaging modality in the field of heritage works conservation. The data acquired by OCT provides both 3D surface information of the object and structure information underneath the surface. Therefore, cross-sectional information on the object can be utilized to study layer structure of the painting and brush stroke techniques used by the artist. However, as demonstrated in previous studies, OCT has limited capability in high-definition (HD) examination of paintings or murals that are in macroscopic scale. HD examination of heritage works needs to scan large areas and process huge amounts of data, while OCT imaging has a limited field of view and processing power. To further advance the application of OCT in the conservation of heritage works, we demonstrate what we believe is a novel high-speed, large field-of-view (FOV) OCT imaging platform. Our results suggest that this OCT platform has the potential to become a nondestructive alternative for the analysis and conservation of paintings and murals.

  6. Imaging natural and artificial demineralization on dentin surfaces with polarization sensitive optical coherence tomography.

    Science.gov (United States)

    Manesh, Saman K; Darling, Cynthia L; Fried, Daniel

    2008-01-01

    The purpose of this study was to assess the potential of polarization sensitive optical coherence tomography (PS-OCT) to measure non-destructively the severity of natural and artificial caries lesions in dentin and determine the efficacy of intervention with anti-caries agents. Although several studies have demonstrated the utility of PS-OCT to image caries lesions in enamel and to quantify the lesion severity, only a few studies have focused on lesions in dentin. In this study images of natural root caries lesions on extracted human teeth were acquired with PS-OCT. In addition artificial lesions were produced in dentin after 12 days of exposure to a demineralization solution at a pH of 5.0. Before exposure, three incisions were made on the sample surfaces using Er:YAG laser irradiation and selected areas were treated with topical fluoride. PS-OCT images were acquired using a high power (45-mw) 1310-nm superluminescent diode with a bandwidth of 35-nm. PS-OCT was able to measure demineralization in dentin to a depth of ~ 1 mm. Polarized light microscopy and microradiography were used to measure lesion severity on histological thin sections for comparison. PS-OCT successfully measured the inhibition of demineralization by topical fluoride. Er:YAG laser irradiation did not significantly increase or decrease the rate of dentin demineralization.

  7. Coherent features of the Alpine mantle slabs imaged by recent seismic tomography studies

    Science.gov (United States)

    Brueckl, E.; Brueckl, J.; Keller, G. R.; Dando, B.

    2012-04-01

    The bifurcation of the East Alpine mountain range into branches extending northeastward to the Carpathians and southeastward to the Dinarides represents a triple junction between the European platform (EU), the Adriatic micro-plate (AD), and the Pannonian fragment (PA). During the last decade, controlled source and passive source seismic data have provided a variety of detailed images of the lithosphere and upper mantle in this area. However, the geodynamic interpretation of lithospheric slabs under the Alpine - Adriatic collision zone is still under debate. So far, arguments have been based mainly on images provided by individual seismic tomography studies. In order to enhance robust features of the upper mantle structure, we have averaged four tomographic models, weighted according to their coverage by seismic stations and boundaries of high resolution. We achieved an image of the Alpine slab of unprecedented clarity. It extends coherently from the border between the Western Alps and the Apennines to the EU-AD-PA triple junction, dipping southeastward in the west and nearly vertically in the east. The whole slab can be connected to European mantle lithosphere and a flip of subduction polarity must not be induced. The geometry of the slab infers also additional constraints on the development of the triple junction during the post-collision phase of the Eastern Alps.

  8. Three-dimensional imaging of the developing mouse female reproductive organs with optical coherence tomography

    Science.gov (United States)

    Burton, Jason C.; Wang, Shang; Behringer, Richard R.; Larina, Irina V.

    2016-03-01

    Infertility is a known major health concern and is estimated to impact ~15% of couples in the U.S. The majority of failed pregnancies occur before or during implantation of the fertilized embryo into the uterus. Understanding the mechanisms regulating development by studying mouse reproductive organs could significantly contribute to an improved understanding of normal development of reproductive organs and developmental causes of infertility in humans. Towards this goal, we report a three-dimensional (3D) imaging study of the developing mouse reproductive organs (ovary, oviduct, and uterus) using optical coherence tomography (OCT). In our study, OCT was used for 3D imaging of reproductive organs without exogenous contrast agents and provides micro-scale spatial resolution. Experiments were conducted in vitro on mouse reproductive organs ranging from the embryonic day 14.5 to adult stages. Structural features of the ovary, oviduct, and uterus are presented. Additionally, a comparison with traditional histological analysis is illustrated. These results provide a basis for a wide range of infertility studies in mouse models. Through integration with traditional genetic and molecular biology approaches, this imaging method can improve understanding of ovary, oviduct, and uterus development and function, serving to further contribute to our understanding of fertility and infertility.

  9. The application of optical coherence tomography to image subsurface tissue structure of Antarctic krill Euphausia superba.

    Directory of Open Access Journals (Sweden)

    Nicola Bellini

    Full Text Available Many small open ocean animals, such as Antarctic krill, are an important part of marine ecosystems. To discover what will happen to animals such as krill in a changing ocean, experiments are run in aquaria where conditions can be controlled to simulate water characteristics predicted to occur in the future. The response of individual animals to changing water conditions can be hard to observe, and with current observation techniques it is very difficult to follow the progress of an individual animal through its life. Optical coherence tomography (OCT is an optical imaging technique that allows images at high resolution to be obtained from depths up to a few millimeters inside biological specimens. It is compatible with in vivo imaging and can be used repeatedly on the same specimens. In this work, we show how OCT may be applied to post mortem krill samples and how important physiological data such as shell thickness and estimates of organ volume can be obtained. Using OCT we find an average value for the thickness of krill exoskeleton to be (30±4 µm along a 1 cm length of the animal body. We also show that the technique may be used to provide detailed imagery of the internal structure of a pleopod joint and provide an estimate for the heart volume of (0.73±0.03 mm3.

  10. Influence of dental resin material composition on cross-polarization-optical coherence tomography imaging

    Science.gov (United States)

    Lammeier, Carmen; Li, YuPing; Lunos, Scott; Fok, Alex; Rudney, Joel; Jones, Robert S.

    2012-10-01

    The purpose of this study was to investigate cross-polarization-optical coherence tomography (CP-OCT) signal attenuation through different resin material compositions. Four distinct composite systems were used: Filtek supreme ultra (FSU) (3M ESPE), IPS empress direct (EMD) (Ivoclar Vivadent), estelite sigma quick (SQK) (Tokuyama Dental), and Z100 (3M ESPE). Cross-sectional images of different composite-demineralized phantoms (n=108) were collected using a 1310-nm intraoral cross-polarization swept source OCT (CP-OCT) imaging system. %T quantified the CP-OCT signal attenuation. Scanning electron microscopy, transmission electron microscopy, and energy-dispersive x-ray spectrometer chemical analysis was utilized to determine how different matrix/filler compositions affected attenuation of the near infrared (NIR) signal. CP-OCT imaging of dental resin composites showed enormous variation in signal attenuation. For each of our composite systems, there was not a consistent attenuation difference in the NIR signal for A to D shades. The four composites had similar measured backscattering values but attenuated the overall signal to different degrees. When comparing the A2 shades between the four different composite systems, the order of highest to lowest of %T was EMD>Z100, FSU>SQK (ANOVA, Tukey, pcomposite materials affect CP-OCT signal attenuation.

  11. Methodology for fully automated segmentation and plaque characterization in intracoronary optical coherence tomography images.

    Science.gov (United States)

    Athanasiou, Lambros S; Bourantas, Christos V; Rigas, George; Sakellarios, Antonis I; Exarchos, Themis P; Siogkas, Panagiotis K; Ricciardi, Andrea; Naka, Katerina K; Papafaklis, Michail I; Michalis, Lampros K; Prati, Francesco; Fotiadis, Dimitrios I

    2014-02-01

    Optical coherence tomography (OCT) is a light-based intracoronary imaging modality that provides high-resolution cross-sectional images of the luminal and plaque morphology. Currently, the segmentation of OCT images and identification of the composition of plaque are mainly performed manually by expert observers. However, this process is laborious and time consuming and its accuracy relies on the expertise of the observer. To address these limitations, we present a methodology that is able to process the OCT data in a fully automated fashion. The proposed methodology is able to detect the lumen borders in the OCT frames, identify the plaque region, and detect four tissue types: calcium (CA), lipid tissue (LT), fibrous tissue (FT), and mixed tissue (MT). The efficiency of the developed methodology was evaluated using annotations from 27 OCT pullbacks acquired from 22 patients. High Pearson's correlation coefficients were obtained between the output of the developed methodology and the manual annotations (from 0.96 to 0.99), while no significant bias with good limits of agreement was shown in the Bland-Altman analysis. The overlapping areas ratio between experts' annotations and methodology in detecting CA, LT, FT, and MT was 0.81, 0.71, 0.87, and 0.81, respectively.

  12. From supersonic shear wave imaging to full-field optical coherence shear wave elastography

    Science.gov (United States)

    Nahas, Amir; Tanter, Mickaël; Nguyen, Thu-Mai; Chassot, Jean-Marie; Fink, Mathias; Claude Boccara, A.

    2013-12-01

    Elasticity maps of tissue have proved to be particularly useful in providing complementary contrast to ultrasonic imaging, e.g., for cancer diagnosis at the millimeter scale. Optical coherence tomography (OCT) offers an endogenous contrast based on singly backscattered optical waves. Adding complementary contrast to OCT images by recording elasticity maps could also be valuable in improving OCT-based diagnosis at the microscopic scale. Static elastography has been successfully coupled with full-field OCT (FF-OCT) in order to realize both micrometer-scale sectioning and elasticity maps. Nevertheless, static elastography presents a number of drawbacks, mainly when stiffness quantification is required. Here, we describe the combination of two methods: transient elastography, based on speed measurements of shear waves induced by ultrasonic radiation forces, and FF-OCT, an en face OCT approach using an incoherent light source. The use of an ultrafast ultrasonic scanner and an ultrafast camera working at 10,000 to 30,000 images/s made it possible to follow shear wave propagation with both modalities. As expected, FF-OCT is found to be much more sensitive than ultrafast ultrasound to tiny shear vibrations (a few nanometers and micrometers, respectively). Stiffness assessed in gel phantoms and an ex vivo rat brain by FF-OCT is found to be in good agreement with ultrasound shear wave elastography.

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

    Directory of Open Access Journals (Sweden)

    M. Esmaeili

    2017-01-01

    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. Optical coherence tomography (OCT) imaging and computer aided diagnosis of human cervical tissue specimens

    Science.gov (United States)

    Bazant-Hegemark, F.; Stone, N.; Read, M. D.; McCarthy, K.; Wang, R. K.

    2007-07-01

    The keyword for management of cervical cancer is prevention. The present program within the UK, the 'National Health Service (NHS) cervical screening programme' (NHSCSP), is based on cytology. Although the program has reduced the incidence of cervical cancer, this program requires patient follow ups and relies on diagnostic biopsying. There is potential for reducing costs and workload within the NHS, and relieving anxiety of patients. In this study, Optical Coherence Tomography (OCT) was investigated for its capability to improve this situation. Our time domain bench top system used a superluminescent diode (Superlum), centre wave length ~1.3 μm, resolution (air) ~15 μm. Tissue samples were obtained according to the ethics approval by Gloucestershire LREC, Nr. 05/Q2005/123. 1387 images of 199 participants have been compared with histopathology results and categorized accordingly. Our OCT images do not reach the clarity and resolution of histopathology. Further, establishing and recognizing features of diagnostic significance seems difficult. Automated classification would allow one to take decision-making to move from the subjective appraisal of a physician to an objective assessment. Hence we investigated a classification algorithm for its ability in recognizing pre-cancerous stages from OCT images. The initial results show promise.

  15. In vivo coherent Raman imaging of the melanomagenesis-associated pigment pheomelanin

    Science.gov (United States)

    Wang, Hequn; Osseiran, Sam; Igras, Vivien; Nichols, Alexander J.; Roider, Elisabeth M.; Pruessner, Joachim; Tsao, Hensin; Fisher, David E.; Evans, Conor L.

    2016-11-01

    Melanoma is the most deadly form of skin cancer with a yearly global incidence over 232,000 patients. Individuals with fair skin and red hair exhibit the highest risk for developing melanoma, with evidence suggesting the red/blond pigment known as pheomelanin may elevate melanoma risk through both UV radiation-dependent and -independent mechanisms. Although the ability to identify, characterize, and monitor pheomelanin within skin is vital for improving our understanding of the underlying biology of these lesions, no tools exist for real-time, in vivo detection of the pigment. Here we show that the distribution of pheomelanin in cells and tissues can be visually characterized non-destructively and noninvasively in vivo with coherent anti-Stokes Raman scattering (CARS) microscopy, a label-free vibrational imaging technique. We validated our CARS imaging strategy in vitro to in vivo with synthetic pheomelanin, isolated melanocytes, and the Mc1re/e, red-haired mouse model. Nests of pheomelanotic melanocytes were observed in the red-haired animals, but not in the genetically matched Mc1re/e; Tyrc/c (“albino-red-haired”) mice. Importantly, samples from human amelanotic melanomas subjected to CARS imaging exhibited strong pheomelanotic signals. This is the first time, to our knowledge, that pheomelanin has been visualized and spatially localized in melanocytes, skin, and human amelanotic melanomas.

  16. Optical Coherence Tomography and Magnetic Resonance Imaging in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder.

    Science.gov (United States)

    Manogaran, Praveena; Hanson, James V M; Olbert, Elisabeth D; Egger, Christine; Wicki, Carla; Gerth-Kahlert, Christina; Landau, Klara; Schippling, Sven

    2016-11-15

    Irreversible disability in multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) is largely attributed to neuronal and axonal degeneration, which, along with inflammation, is one of the major pathological hallmarks of these diseases. Optical coherence tomography (OCT) is a non-invasive imaging tool that has been used in MS, NMOSD, and other diseases to quantify damage to the retina, including the ganglion cells and their axons. The fact that these are the only unmyelinated axons within the central nervous system (CNS) renders the afferent visual pathway an ideal model for studying axonal and neuronal degeneration in neurodegenerative diseases. Structural magnetic resonance imaging (MRI) can be used to obtain anatomical information about the CNS and to quantify evolving pathology in MS and NMOSD, both globally and in specific regions of the visual pathway including the optic nerve, optic radiations and visual cortex. Therefore, correlations between brain or optic nerve abnormalities on MRI, and retinal pathology using OCT, may shed light on how damage to one part of the CNS can affect others. In addition, these imaging techniques can help identify important differences between MS and NMOSD such as disease-specific damage to the visual pathway, trans-synaptic degeneration, or pathological changes independent of the underlying disease process. This review focuses on the current knowledge of the role of the visual pathway using OCT and MRI in patients with MS and NMOSD. Emphasis is placed on studies that employ both MRI and OCT to investigate damage to the visual system in these diseases.

  17. Real time imaging of peripheral nerve vasculature using optical coherence angiography

    Science.gov (United States)

    Vasudevan, Srikanth; Kumsa, Doe; Takmakov, Pavel; Welle, Cristin G.; Hammer, Daniel X.

    2016-03-01

    The peripheral nervous system (PNS) carries bidirectional information between the central nervous system and distal organs. PNS stimulation has been widely used in medical devices for therapeutic indications, such as bladder control and seizure cessation. Investigational uses of PNS stimulation include providing sensory feedback for improved control of prosthetic limbs. While nerve safety has been well documented for stimulation parameters used in marketed devices, novel PNS stimulation devices may require alternative stimulation paradigms to achieve maximum therapeutic benefit. Improved testing paradigms to assess the safety of stimulation will expedite the development process for novel PNS stimulation devices. The objective of this research is to assess peripheral nerve vascular changes in real-time with optical coherence angiography (OCA). A 1300-nm OCA system was used to image vasculature changes in the rat sciatic nerve in the region around a surface contacting single electrode. Nerves and vasculature were imaged without stimulation for 180 minutes to quantify resting blood vessel diameter. Walking track analysis was used to assess motor function before and 6 days following experiments. There was no significant change in vessel diameter between baseline and other time points in all animals. Motor function tests indicated the experiments did not impair functionality. We also evaluated the capabilities to image the nerve during electrical stimulation in a pilot study. Combining OCA with established nerve assessment methods can be used to study the effects of electrical stimulation safety on neural and vascular tissue in the periphery.

  18. Optical coherence tomography angiography of retinal vascular occlusions produced by imaging-guided laser photocoagulation

    Science.gov (United States)

    Soetikno, Brian T.; Shu, Xiao; Liu, Qi; Liu, Wenzhong; Chen, Siyu; Beckmann, Lisa; Fawzi, Amani A.; Zhang, Hao F.

    2017-01-01

    Retinal vascular occlusive diseases represent a major form of vision loss worldwide. Rodent models of these diseases have traditionally relied upon a slit-lamp biomicroscope to help visualize the fundus and subsequently aid delivery of high-power laser shots to a target vessel. Here we describe a multimodal imaging system that can produce, image, and monitor retinal vascular occlusions in rodents. The system combines a spectral-domain optical coherence tomography system for cross-sectional structural imaging and three-dimensional angiography, and a fluorescence scanning laser ophthalmoscope for Rose Bengal monitoring and high-power laser delivery to a target vessel. This multimodal system facilitates the precise production of occlusions in the branched retinal veins, central retinal vein, and branched retinal arteries. Additionally, changes in the retinal morphology and retinal vasculature can be longitudinally documented. With our device, retinal vascular occlusions can be easily and consistently created, which paves the way for futures studies on their pathophysiology and therapeutic targets. PMID:28856036

  19. Fiber bundle based probe with polarization for coherent anti-Stokes Raman scattering microendoscopy imaging

    Science.gov (United States)

    Liu, Zhengfan; Wang, Zhiyong; Wang, Xi; Xu, Xiaoyun; Chen, Xu; Cheng, Jie; Li, Xiaoyan; Chen, Shufen; Xin, Jianguo; Wong, Stephen T. C.

    2013-02-01

    The ability to visualize cellular structures and tissue molecular signatures in a live body could revolutionize the practice of surgery. Specifically, such technology is promising for replacing tissue extraction biopsy and offering new strategies for a broad range of intraoperative or surgical applications, including early cancer detection, tumor margin identification, nerve damage avoidance, and surgical outcomes enhancement. Coherent anti-Stokes Raman scattering (CARS) microendoscopy offers a way to achieve this with label-free imaging capability and sub-cellular resolution. However, efficient collection of epi-CARS signals and reduction of nonlinear effects in fibers are two major challenges encountered in the development of fiber-based CARS microendoscopy. To circumvent this problem, we designed and developed a fiber bundle for a CARS microendoscopy prototype. The excitation lasers were delivered by a single multimode fiber at the center of the bundle while the epi-CARS signals were collected by multiple MMFs surrounding the central fiber. A polarization scheme was employed to suppress the four-wave mixing (FWM) effect in the excitation fiber. Our experimental results suggest that, with this fiber bundle and the polarization FWM-suppressing scheme, the signal-to-noise ratio of the CARS images was greatly enhanced through a combination of high collection efficiency of epi-CARS signals, isolation of excitation lasers, and suppression of FWM. Tissue imaging capability of the microendoscopy prototype was demonstrated by ex vivo imaging on mouse skin and lung tissues. This fiber bundle-based CARS microendoscopy prototype, with the polarization FWM-suppressing scheme, offers a promising platform for constructing efficient fiber-based CARS microendoscopes for label free intraoperative imaging applications.

  20. Cervical inlet patch-optical coherence tomography imaging and clinical significance

    Institute of Scientific and Technical Information of China (English)

    Chao Zhou; Tejas Kirtane; Tsung-Han Tsai; Hsiang-Chieh Lee; Desmond C Adler; Joseph M Schmitt; Qin Huang; James G Fujimoto; Hiroshi Mashimo

    2012-01-01

    AIM:To demonstrate the feasibility of optical coherence tomography (OCT) imaging in differentiating cervical inlet patch (CIP) from normal esophagus,Barrett's esophagus (BE),normal stomach and duodenum.METHODS:This study was conducted at the Veterans Affairs Boston Healthcare System (VABHS).Patients undergoing standard esophagogastroduodenoscopy at VABHS,including one patient with CIP,one representative patient with BE and three representative normal subjects were included.White light video endoscopy was performed and endoscopic 3D-OCT images were obtained in each patient using a prototype OCT system.The OCT imaging probe passes through the working channel of the endoscope to enable simultaneous video endoscopy and 3D-OCT examination of the human gastrointestinal (GI) tract.Standard hematoxylin and eosin (H and E) histology was performed on biopsy or endoscopic mucosal resection specimens in order to compare and validate the 3D-OCT data.RESULTS:CIP was observed from a 68-year old male with gastroesophageal reflux disease.The CIP region appeared as a pink circular lesion in the upper esophagus under white light endoscopy.OCT imaging over the CIP region showed columnar epithelium structure,which clearly contrasted the squamous epithelium structure from adjacent normal esophagus.3D-OCT images obtained from other representative patients demonstrated distinctive patterns of the normal esophagus,BE,normal stomach,and normal duodenum bulb.Microstructures,such as squamous epithelium,lamina propria,muscularis mucosa,muscularis propria,esophageal glands,Barrett's glands,gastric mucosa,gastric glands,and intestinal mucosal villi were clearly observed with OCT and matched with H and E histology.These results demonstrated the feasibility of using OCT to evaluate GI tissue morphology in situ and in real-time.CONCLUSION:We demonstrate in situ evaluation of CIP microstructures using 3D-OCT,which may be a useful tool for future diagnosis and follow-up of patients with CIP.

  1. Ex vivo optical coherence tomography and laser induced fluorescence spectroscopy imaging of murine gastrointestinal tract

    Science.gov (United States)

    Hariri, Lida; Tumlinson, Alexandre R.; Wade, Norman; Besselsen, David; Utzinger, Urs; Gerner, Eugene; Barton, Jennifer

    2005-04-01

    Optical Coherence Tomography (OCT) and Laser Induced Fluorescence Spectroscopy (LIF) have separately been found to have clinical potential in identifying human gastrointestinal (GI) pathologies, yet their diagnostic capability in mouse models of human disease is unknown. We combine the two modalities to survey the GI tract of a variety of mouse strains and sample dysplasias and inflammatory bowel disease (IBD) of the small and large intestine. Segments of duodenum and lower colon 2.5 cm in length and the entire esophagus from 10 mice each of two colon cancer models (ApcMin and AOM treated A/J) and two IBD models (Il-2 and Il-10) and 5 mice each of their respective controls were excised. OCT images and LIF spectra were obtained simultaneously from each tissue sample within 1 hour of extraction. Histology was used to classify tissue regions as normal, Peyer"s patch, dysplasia, adenoma, or IBD. Features in corresponding regions of OCT images were analyzed. Spectra from each of these categories were averaged and compared via the student's t-test. Features in OCT images correlated to histology in both normal and diseased tissue samples. In the diseased samples, OCT was able to identify early stages of mild colitis and dysplasia. In the sample of IBD, the LIF spectra displayed unique peaks at 635nm and 670nm, which were attributed to increased porphyrin production in the proliferating bacteria of the disease. These peaks have the potential to act as a diagnostic for IBD. OCT and LIF appear to be useful and complementary modalities for imaging mouse models.

  2. Choroidal structure determined by binarizing optical coherence tomography images in eyes with reticular pseudodrusen

    Science.gov (United States)

    Masuda, Naonori; Kojima, Masashi; Yamashita, Mariko; Nishi, Tomo; Ogata, Nahoko

    2017-01-01

    Purpose To compare the choroidal structure beneath the macular area in eyes with reticular pseudodrusen (RPD) and age-matched controls. Methods This study was performed at Nara Medical University Hospital, Japan. Twenty eyes of 14 patients (82.3±4.2 years, mean ± standard deviation) with RPD and 35 eyes of 20 age-matched controls (81.5±6.0 years) were studied. The choroidal structure was determined by binarizing the images obtained by enhanced depth imaging optical coherence tomography in all patients and controls. The total, luminal, and stromal choroidal areas were quantified by the binarization method. Results The total choroidal area of the eyes with RPD was significantly smaller than that of control eyes (P=0.001, unpaired t-test). Both the luminal and stromal areas in eyes with RPD were significantly smaller than that of control eyes (P=0.001, paired t-test), but there was no significant difference in the luminal/stromal ratio between eyes with RPD and control eyes. Conclusion The total, luminal, and stromal choroidal areas in eyes with RPD were smaller than those of the control eyes. The reduction of the choroidal luminal and stromal areas may be due to a loss of the oxygen demand of the choroid due to RPE dysfunction. PMID:28490860

  3. A new optical image cryptosystem based on two-beam coherent superposition and unequal modulus decomposition

    Science.gov (United States)

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

    2016-04-01

    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.

  4. Polarization-sensitive optical coherence tomography for imaging of biological tissues

    Science.gov (United States)

    Chen, Xiaodong; Wang, Yi; Li, Wanhui; Yu, Daoyin

    2006-09-01

    Polarization sensitive optical coherence tomography (PS-OCT) is a new non-contact and non-invasive method for measuring the change of birefringence in biological tissues caused by pathological changes of body. It has great potential in imaging the structural properties of turbid biological media because the polarization state of light backscattered from biological tissues is influenced by the birefringence of fibrous structures. The arrangement is based on a Michelson interferometer with use of quarter-wave plates and polarimeter. Through the detection of light backscattered from biological tissues and reflected from a reference mirror, the optical phase delay between orthogonal polarization compositions propagating in the birefringence media can be measured. PS-OCT is a powerful tool for research of tendon, dentin, lesions, which have strong polarization effective. We in this paper describe the experimental scheme and its mathematical representation, along with the theory of PS-OCT imaging. Besides, we introduce a fiber-based PS-OCT system for measuring the tissue birefringence.

  5. Needle Segmentation in Volumetric Optical Coherence Tomography Images for Ophthalmic Microsurgery

    Directory of Open Access Journals (Sweden)

    Mingchuan Zhou

    2017-07-01

    Full Text Available Needle segmentation is a fundamental step for needle reconstruction and image-guided surgery. Although there has been success stories in needle segmentation for non-microsurgeries, the methods cannot be directly extended to ophthalmic surgery due to the challenges bounded to required spatial resolution. As the ophthalmic surgery is performed by finer and smaller surgical instruments in micro-structural anatomies, specifically in retinal domains, difficulties are raised for delicate operation and sensitive perception. To address these challenges, in this paper we investigate needle segmentation in ophthalmic operation on 60 Optical Coherence Tomography (OCT cubes captured during needle injection surgeries on ex-vivo pig eyes. Furthermore, we developed two different approaches, a conventional method based on morphological features (MF and a specifically designed full convolution neural networks (FCN method, moreover, we evaluate them on the benchmark for needle segmentation in the volumetric OCT images. The experimental results show that FCN method has a better segmentation performance based on four evaluation metrics while MF method has a short inference time, which provides valuable reference for future works.

  6. Agreement between Gonioscopic Examination and Swept Source Fourier Domain Anterior Segment Optical Coherence Tomography Imaging

    Directory of Open Access Journals (Sweden)

    Mohammed Rigi

    2016-01-01

    Full Text Available Purpose. To evaluate interobserver, intervisit, and interinstrument agreements for gonioscopy and Fourier domain anterior segment optical coherence tomography (FD ASOCT for classifying open and narrow angle eyes. Methods. Eighty-six eyes with open or narrow anterior chamber angles were included. The superior angle was classified open or narrow by 2 of 5 glaucoma specialists using gonioscopy and imaged by FD ASOCT in the dark. The superior angle of each FD ASOCT image was graded as open or narrow by 2 masked readers. The same procedures were repeated within 6 months. Kappas for interobserver and intervisit agreements for each instrument and interinstrument agreements were calculated. Results. The mean age was 50.9 (±18.4 years. Interobserver agreements were moderate to good for both gonioscopy (0.57 and 0.69 and FD ASOCT (0.58 and 0.75. Intervisit agreements were moderate to excellent for both gonioscopy (0.53 to 0.86 and FD ASOCT (0.57 and 0.85. Interinstrument agreements were fair to good (0.34 to 0.63, with FD ASOCT classifying more angles as narrow than gonioscopy. Conclusions. Both gonioscopy and FD ASOCT examiners were internally consistent with similar interobserver and intervisit agreements for angle classification. Agreement between instruments was fair to good, with FD ASOCT classifying more angles as narrow than gonioscopy.

  7. Choroidal structure determined by binarizing optical coherence tomography images in eyes with reticular pseudodrusen.

    Science.gov (United States)

    Masuda, Naonori; Kojima, Masashi; Yamashita, Mariko; Nishi, Tomo; Ogata, Nahoko

    2017-01-01

    To compare the choroidal structure beneath the macular area in eyes with reticular pseudodrusen (RPD) and age-matched controls. This study was performed at Nara Medical University Hospital, Japan. Twenty eyes of 14 patients (82.3±4.2 years, mean ± standard deviation) with RPD and 35 eyes of 20 age-matched controls (81.5±6.0 years) were studied. The choroidal structure was determined by binarizing the images obtained by enhanced depth imaging optical coherence tomography in all patients and controls. The total, luminal, and stromal choroidal areas were quantified by the binarization method. The total choroidal area of the eyes with RPD was significantly smaller than that of control eyes (P=0.001, unpaired t-test). Both the luminal and stromal areas in eyes with RPD were significantly smaller than that of control eyes (P=0.001, paired t-test), but there was no significant difference in the luminal/stromal ratio between eyes with RPD and control eyes. The total, luminal, and stromal choroidal areas in eyes with RPD were smaller than those of the control eyes. The reduction of the choroidal luminal and stromal areas may be due to a loss of the oxygen demand of the choroid due to RPE dysfunction.

  8. Choroidal Structure in Children with Anisohypermetropic Amblyopia Determined by Binarization of Optical Coherence Tomographic Images.

    Science.gov (United States)

    Nishi, Tomo; Ueda, Tetsuo; Mizusawa, Yuutaro; Shinomiya, Kayo; Semba, Kentaro; Mitamura, Yoshinori; Sonoda, Shozo; Uchino, Eisuke; Sakamoto, Taiji; Ogata, Nahoko

    2016-01-01

    To compare the choroidal structure of the subfoveal area in the eyes of children with anisohypermetropic amblyopia to that of the fellow eyes and to age-matched controls using a binarization method of the images obtained by enhanced depth imaging optical coherence tomography (EDI-OCT). This study was performed at Nara Medical University Hospital, Tokushima University Hospital, and Kagoshima University Hospital, Japan. Forty amblyopic eyes with anisohypermetropic amblyopia and their fellow eyes (5.9 ± 2.1 years, mean ± standard deviation), and 103 age-matched controls (6.7 ± 2.4 years) were studied. The control eyes were divided into myopic, emmetropic, and hyperopic eyes. The total choroidal area, luminal area and stromal area of the subfoveal choroid were measured by the binarization method. The luminal/stromal ratio and the axial length of the amblyopic eyes were compared to that of the control eyes. The total choroidal area in the amblyopic eyes was significantly larger than that of the fellow eyes (P = 0.005). The luminal/stromal ratio was significantly larger in the amblyopic eyes than that of the fellow eyes (Pcontrol hyperopic eyes (Pcontrol eyes (r = -0.30, P = 0.001), but no significant correlation was found in the amblyopic eyes. The choroidal structure of the amblyopic eyes was different from that of the fellow and the control hyperopic eyes. The choroidal changes are related to amblyopia.

  9. Imaging caries lesions and lesion progression with polarization-sensitive optical coherence tomography

    Science.gov (United States)

    Fried, Daniel; Xie, John; Shafi, Sahar; Featherstone, John D. B.; Breunig, Thomas; Le, Charles Q.

    2002-06-01

    New diagnostic tools are needed for the characterization of dental caries in the early stages of development. If carious lesions are detected early enough, they can be arrested without the need for surgical intervention. The objective of this study was to demonstrate that polarization sensitive optical coherence tomography (PS-OCT) can be used for the imaging of early caries lesions and for the monitoring of lesion progression over time. High-resolution polarization resolved images were acquired of natural caries lesions and simulated caries lesions of varying severity created over time periods of 1 to 14 days. Linearly polarized light was incident on the tooth samples and the reflected intensity in both orthogonal polarizations was measured. PS-OCT was invaluable for removing the confounding influence of surface reflections and native birefringence and for resolving the surface structure of caries lesions. This study demonstrated that PS-OCT is well suited for the resolution of interproximal and occlusal caries, early root caries, and secondary caries around composite fillings. Longitudinal measurements of lesion progression established a strong correlation (p<0.001) between the reflected light from the lesion area and the square root of time indicating that PS-OCT is well suited for monitoring changes in enamel mineralization over time.

  10. Optical coherence tomography for image-guided dermal filler injection and biomechanical evaluation

    Science.gov (United States)

    Singh, Manmohan; Wang, Shang; Yee, Richard W.; Han, Zhaolong; Aglyamov, Salavat R.; Larin, Kirill V.

    2017-02-01

    Dermal fillers are a very popular anti-ag ing treatment with estimated sales in the billions of dollars and millions of procedures performed. As the aging population continues to grow, these figures are only e xpected to increase. Dermal fillers have various compositions depending on their intended applicati on. Reactions to dermal fillers can be severe, such as ischemic events and filler migration to the eyes. Howe ver, these adverse reactions are rare. Nevertheless, the capability to perform imag e-guided filler injections would minimize th e risk of such reacti ons. In addition, the biomechanical properties of various fillers have been evalua ted, but there has been no investigation on the effects of filler on the biomechanical properties of skin. In this work, we utilize optical cohe rence tomography (OCT) for visualizing dermal filler injections with micrometer-scale sp atial resolution. In addition, we utilize noncontact optical coherence elastography (OCE) to quantify the changes in the biomechan ical properties of pig skin after the dermal filler injections. OCT was successfully able to visualize the dermal filler injecti on process, and OCE showed that the viscoelasticity of the pig skin was increased locally at the filler injection sites. OCT may be able to provide real-time image guidance in 3D, and when combined with functional OCT techniques such as optical microangiography, could be used to avoid blood vessels during the injection.

  11. Review of spectral domain enhanced depth imaging optical coherence tomography of tumors of the choroid

    Directory of Open Access Journals (Sweden)

    Carol L Shields

    2015-01-01

    Full Text Available Background: Spectral domain enhanced depth imaging optical coherence tomography (EDI-OCT can provide anatomic localization of intraocular tumors. Aims: The aim was to identify topographical and intrinsic patterns of choroidal tumors on EDI-OCT. Settings and Design: Retrospective review. Materials and Methods: Analysis of published reports and personal observations using office based EDI-OCT. Results: Using EDI-OCT, choroidal nevus displayed a smooth, dome-shaped topography with overlying retinal pigment epithelium alterations, drusen, and occasional subretinal cleft demonstrating photoreceptor loss. Small choroidal melanoma showed smooth, moderately dome-shaped topography, commonly with overlying shallow subretinal fluid that often depicted "shaggy" photoreceptors. Choroidal metastasis showed a minimally "lumpy, bumpy" surface topography and with overlying subretinal fluid and shaggy photoreceptors. Choroidal hemangioma showed a smooth, dome-shaped topography, with expansion of the affected small, medium, and large choroidal vessels. Choroidal lymphoma showed varying topography with increasing tumor thickness as "flat, rippled, or undulating (seasick" surface. Choroidal osteoma displayed a smooth undulating surface with visible intralesional horizontal lines suggestive of bone lamellae and occasional horizontal and vertical tubules with intralesional "spongy" flecks. Choroidal melanocytosis appeared as uniformly thickened choroid with increased stromal density surrounding the normal choroidal vascular structures. Conclusions: Enhanced depth imaging-OCT can depict characteristic patterns that are suggestive of various choroidal tumors.

  12. Multiscale Tikhonov-Total Variation Image Restoration Using Spatially Varying Edge Coherence Exponent.

    Science.gov (United States)

    Prasath, V B Surya; Vorotnikov, Dmitry; Pelapur, Rengarajan; Jose, Shani; Seetharaman, Guna; Palaniappan, Kannappan

    2015-12-01

    Edge preserving regularization using partial differential equation (PDE)-based methods although extensively studied and widely used for image restoration, still have limitations in adapting to local structures. We propose a spatially adaptive multiscale variable exponent-based anisotropic variational PDE method that overcomes current shortcomings, such as over smoothing and staircasing artifacts, while still retaining and enhancing edge structures across scale. Our innovative model automatically balances between Tikhonov and total variation (TV) regularization effects using scene content information by incorporating a spatially varying edge coherence exponent map constructed using the eigenvalues of the filtered structure tensor. The multiscale exponent model we develop leads to a novel restoration method that preserves edges better and provides selective denoising without generating artifacts for both additive and multiplicative noise models. Mathematical analysis of our proposed method in variable exponent space establishes the existence of a minimizer and its properties. The discretization method we use satisfies the maximum-minimum principle which guarantees that artificial edge regions are not created. Extensive experimental results using synthetic, and natural images indicate that the proposed multiscale Tikhonov-TV (MTTV) and dynamical MTTV methods perform better than many contemporary denoising algorithms in terms of several metrics, including signal-to-noise ratio improvement and structure preservation. Promising extensions to handle multiplicative noise models and multichannel imagery are also discussed.

  13. Kernel regression based segmentation of optical coherence tomography images with diabetic macular edema.

    Science.gov (United States)

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

    2015-04-01

    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.

  14. In vivo imaging of raptor retina with ultra high resolution spectral domain optical coherence tomography

    Science.gov (United States)

    Ruggeri, Marco; Major, James C., Jr.; McKeown, Craig; Wehbe, Hassan; Jiao, Shuliang; Puliafito, Carmen A.

    2008-02-01

    Among birds, raptors are well known for their exceptional eyesight, which is partly due to the unique structure of their retina. Because the raptor retina is the most advanced of any animal species, in vivo examination of its structure would be remarkable. Furthermore, a noticeable percentage of traumatic ocular injuries are identified in birds of prey presented to rehabilitation facilities. Injuries affecting the posterior segment have been considered as a major impact on raptor vision. Hence, in vivo examination of the structure of the posterior segment of the raptors would be helpful for the diagnosis of traumatized birds. The purpose of this study is to demonstrate the application of ultrahigh-resolution Spectral Domain Optical Coherence Tomography (SD-OCT) for non contact in vivo imaging of the retina of birds of prey, which to the best of our knowledge has never been attempted. For the first time we present high quality OCT images of the retina of two species of bird of prey, one diurnal hawk and one nocturnal owl.

  15. Measurement of choroid thickness in pregnant women using enhanced depth imaging optical coherence tomography.

    Science.gov (United States)

    Goktas, Sertan; Basaran, Ahmet; Sakarya, Yasar; Ozcimen, Muammer; Kucukaydin, Zehra; Sakarya, Rabia; Basaran, Mustafa; Erdogan, Erkan; Alpfidan, Ismail

    2014-01-01

    To investigate choroidal thickness in healthy pregnant women during different trimesters using enhanced depth imaging optical coherence tomography (EDI-OCT). This prospective study included 90 healthy pregnant women in their first, second, or third trimester (groups 1, 2, and 3, respectively) and 30 non-pregnant healthy women (group 4). The age range for all groups was 18-40 years. Spectral domain optical coherence tomography scans were obtained to estimate the average choroidal thickness. Using EDI-OCT, we measured choroidal thickness manually from the outer border of the retinal pigment epithelium to the inner scleral border at the subfovea, 3 mm temporal, and 3 mm nasal to the fovea. Differences among groups were analyzed by one-way ANOVA. We found a statistically significant difference between groups 2 and group 4 for subfoveal, temporal, and nasal mean choroidal thickness (p=0.007, pchoroidal thickness for group 2 was 395 ± 80 μm, 338 ± 74 μm, and 233 ± 61 μm at the regions subfoveal, temporal, and nasal to the fovea, respectively. In comparison, the mean choroidal thickness for group 4 was 335 ± 86 μm, 274 ± 54 μm, and 200 ± 53 μm at the regions subfoveal, temporal, and nasal to the fovea, respectively. No statistically significant differences were found for choroidal thickness among groups 1-4 (p=0.214, p=0.177, p=0.094, respectively) and between groups 3-4 (p=0.105, p=0.261, p=0.695, respectively) for all measured points. Our results suggest that choroidal thickening can occur at the regions subfoveal, temporal, and nasal to the fovea in the second trimester.

  16. Coherent amplified optical coherence tomography

    Science.gov (United States)

    Zhang, Jun; Rao, Bin; Chen, Zhongping

    2007-07-01

    A technique to improve the signal-to-noise ratio (SNR) of a high speed 1300 nm swept source optical coherence tomography (SSOCT) system was demonstrated. A semiconductor optical amplifier (SOA) was employed in the sample arm to coherently amplify the weak light back-scattered from sample tissue without increasing laser power illuminated on the sample. The image quality improvement was visualized and quantified by imaging the anterior segment of a rabbit eye at imaging speed of 20,000 A-lines per second. The theory analysis of SNR gain is given followed by the discussion on the technologies that can further improve the SNR gain.

  17. Patch-based denoising method using low-rank technique and targeted database for optical coherence tomography image.

    Science.gov (United States)

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

    2017-01-01

    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.

  18. Fully integrated optical coherence tomography, ultrasound, and indocyanine green-based fluorescence tri-modality system for intravascular imaging.

    Science.gov (United States)

    Li, Yan; Jing, Joseph; Qu, Yueqiao; Miao, Yusi; Zhang, Buyun; Ma, Teng; Yu, Mingyue; Zhou, Qifa; Chen, Zhongping

    2017-02-01

    We present a tri-modality imaging system and fully integrated tri-modality probe for intravascular imaging. The tri-modality imaging system is able to simultaneously acquire optical coherence tomography (OCT), ultrasound (US), and fluorescence imaging. Moreover, for fluorescence imaging, we used the FDA-approved indocyanine green (ICG) dye as the contrast agent to target lipid-loaded macrophages. We conducted imaging from a male New Zealand white rabbit to evaluate the performance of the tri-modality system. In addition, tri-modality images of rabbit aortas were correlated with hematoxylin and eosin (H&E) histology to check the measurement accuracy. The fully integrated miniature tri-modality probe, together with the use of ICG dye suggest that the system is of great potential for providing a more accurate assessment of vulnerable plaques in clinical applications.

  19. Multiple defocused coherent diffraction imaging: method for simultaneously reconstructing objects and probe using X-ray free-electron lasers.

    Science.gov (United States)

    Hirose, Makoto; Shimomura, Kei; Suzuki, Akihiro; Burdet, Nicolas; Takahashi, Yukio

    2016-05-30

    The sample size must be less than the diffraction-limited focal spot size of the incident beam in single-shot coherent X-ray diffraction imaging (CXDI) based on a diffract-before-destruction scheme using X-ray free electron lasers (XFELs). This is currently a major limitation preventing its wider applications. We here propose multiple defocused CXDI, in which isolated objects are sequentially illuminated with a divergent beam larger than the objects and the coherent diffraction pattern of each object is recorded. This method can simultaneously reconstruct both objects and a probe from the coherent X-ray diffraction patterns without any a priori knowledge. We performed a computer simulation of the prposed method and then successfully demonstrated it in a proof-of-principle experiment at SPring-8. The prposed method allows us to not only observe broad samples but also characterize focused XFEL beams.

  20. Optical theory of partially coherent thin-film energy-absorbing structures for power detectors and imaging arrays.

    Science.gov (United States)

    Withington, Stafford; Thomas, Christopher N

    2009-06-01

    Free-space power detectors often have energy absorbing structures comprising multilayer systems of patterned thin films. We show that for any system of interacting resistive films, the expectation value of the absorbed power is given by the contraction of two tensor fields: one describes the spatial state of coherence of the incoming radiation, the other the state of coherence to which the detector is sensitive. Equivalently, the natural modes of the optical field scatter power into the natural modes of the detector. We describe a procedure for determining the amplitude, phase, and polarization patterns of a detector's optical modes and their relative responsivities. The procedure gives the state of coherence of the currents flowing in the system and leads to important conceptual insights into the way the pixels of an imaging array interact and extract information from an optical field.

  1. Imaging human retinal pigment epithelium cells using adaptive optics optical coherence tomography

    Science.gov (United States)

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

    2016-03-01

    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.

  2. High-speed swept source optical coherence Doppler tomography for deep brain microvascular imaging

    Science.gov (United States)

    Chen, Wei; You, Jiang; Gu, Xiaochun; Du, Congwu; Pan, Yingtian

    2016-12-01

    Noninvasive microvascular imaging using optical coherence Doppler tomography (ODT) has shown great promise in brain studies; however, high-speed microcirculatory imaging in deep brain remains an open quest. A high-speed 1.3 μm swept-source ODT (SS-ODT) system is reported which was based on a 200 kHz vertical-cavity-surface-emitting laser. Phase errors induced by sweep-trigger desynchronization were effectively reduced by spectral phase encoding and instantaneous correlation among the A-scans. Phantom studies have revealed a significant reduction in phase noise, thus an enhancement of minimally detectable flow down to 268.2 μm/s. Further in vivo validation was performed, in which 3D cerebral-blood-flow (CBF) networks in mouse brain over a large field-of-view (FOV: 8.5 × 5 × 3.2 mm3) was scanned through thinned skull. Results showed that fast flows up to 3 cm/s in pial vessels and minute flows down to 0.3 mm/s in arterioles or venules were readily detectable at depths down to 3.2 mm. Moreover, the dynamic changes of the CBF networks elicited by acute cocaine such as heterogeneous responses in various vessel compartments and at different cortical layers as well as transient ischemic events were tracked, suggesting the potential of SS-ODT for brain functional imaging that requires high flow sensitivity and dynamic range, fast frame rate and a large FOV to cover different brain regions.

  3. Structure-function Investigation of Operando Nanostructured Materials Using Coherent X-ray Diffractive Imaging

    Science.gov (United States)

    Ulvestad, Andrew

    Nanostructured devices promise to help solve grand challenges of our time, including renewable energy generation, storage, and mitigating climate change. Their power lies in the particular influence of the surface on the total free energy when dimensions approach the nanoscale and it is well known that different sizes, shapes, and defects can drastically alter material properties. However, this strength represents a considerable challenge for imaging techniques that can be limited in terms of sample environments, average over large ensembles of particles, and/or lack adequate spatiotemporal resolution for studying the relevant physical processes. The focus of this thesis is the development of in situ coherent X-ray diffractive imaging (CXDI) and its application in imaging strain evolution in battery cathode nanoparticles. Using in situ CXDI, the compressive/tensile strain field in the pristine state is revealed, and found to be linked to a particular concentration of strain inducing Jahn-Teller ions. The evolution of strain during the first charge/discharge cycle shows that the cathode nanoparticle exhibits phase separation. Using the 3D strain field, the strain field energy is calculated and shows interesting hysteresis between charge and discharge. Strain evolution during a disconnection event, in which the cathode nanoparticle is no longer able to exchange electrons and ions with its environment, reveals the formation of a poorly conducting interphase layer. Finally, strain fields were used to study dislocation dynamics in battery nanoparticles. Using the full 3D information, the dislocation line structure is mapped and shown to move in response to charge transfer. The dislocation is used as a way to probe the local material properties and it is discovered that the material enters an ``auxetic", or negative Poisson's ratio, regime.

  4. Imaging retinal nerve fiber bundles using optical coherence tomography with adaptive optics.

    Science.gov (United States)

    Kocaoglu, Omer P; Cense, Barry; Jonnal, Ravi S; Wang, Qiang; Lee, Sangyeol; Gao, Weihua; Miller, Donald T

    2011-08-15

    Early detection of axonal tissue loss in retinal nerve fiber layer (RNFL) is critical for effective treatment and management of diseases such as glaucoma. This study aims to evaluate the capability of ultrahigh-resolution optical coherence tomography with adaptive optics (UHR-AO-OCT) for imaging the RNFL axonal bundles (RNFBs) with 3×3×3μm(3) resolution in the eye. We used a research-grade UHR-AO-OCT system to acquire 3°×3° volumes in four normal subjects and one subject with an arcuate retinal nerve fiber layer defect (n=5; 29-62years). Cross section (B-scans) and en face (C-scan) slices extracted from the volumes were used to assess visibility and size distribution of individual RNFBs. In one subject, we reimaged the same RNFBs twice over a 7month interval and compared bundle width and thickness between the two imaging sessions. Lastly we compared images of an arcuate RNFL defect acquired with UHR-AO-OCT and commercial OCT (Heidelberg Spectralis). Individual RNFBs were distinguishable in all subjects at 3° retinal eccentricity in both cross-sectional and en face views (width: 30-50μm, thickness: 10-15μm). At 6° retinal eccentricity, RNFBs were distinguishable in three of the five subjects in both views (width: 30-45μm, thickness: 20-40μm). Width and thickness RNFB measurements taken 7months apart were strongly correlated (p<0.0005). Mean difference and standard deviation of the differences between the two measurement sessions were -0.1±4.0μm (width) and 0.3±1.5μm (thickness). UHR-AO-OCT outperformed commercial OCT in terms of clarity of the microscopic retina. To our knowledge, these are the first measurements of RNFB cross section reported in the living human eye.

  5. Automated segmentation of lung airway wall area measurements from bronchoscopic optical coherence tomography imaging

    Science.gov (United States)

    Heydarian, Mohammadreza; Choy, Stephen; Wheatley, Andrew; McCormack, David; Coxson, Harvey O.; Lam, Stephen; Parraga, Grace

    2011-03-01

    Chronic Obstructive Pulmonary Disease (COPD) affects almost 600 million people and is currently the fourth leading cause of death worldwide. COPD is an umbrella term for respiratory symptoms that accompany destruction of the lung parenchyma and/or remodeling of the airway wall, the sum of which result in decreased expiratory flow, dyspnea and gas trapping. Currently, x-ray computed tomography (CT) is the main clinical method used for COPD imaging, providing excellent spatial resolution for quantitative tissue measurements although dose limitations and the fundamental spatial resolution of CT limit the measurement of airway dimensions beyond the 5th generation. To address this limitation, we are piloting the use of bronchoscopic Optical Coherence Tomography (OCT), by exploiting its superior spatial resolution of 5-15 micrometers for in vivo airway imaging. Currently, only manual segmentation of OCT airway lumen and wall have been reported but manual methods are time consuming and prone to observer variability. To expand the utility of bronchoscopic OCT, automatic and robust measurement methods are required. Therefore, our objective was to develop a fully automated method for segmenting OCT airway wall dimensions and here we explore several different methods of image-regeneration, voxel clustering and post-processing. Our resultant automated method used K-means or Fuzzy c-means to cluster pixel intensity and then a series of algorithms (i.e. cluster selection, artifact removal, de-noising) was applied to process the clustering results and segment airway wall dimensions. This approach provides a way to automatically and rapidly segment and reproducibly measure airway lumen and wall area.

  6. Macrophagic enhancement in optical coherence tomography imaging by means of superparamagnetic iron oxide nanoparticles.

    Science.gov (United States)

    Gutiérrez-Chico, Juan Luis; Jaguszewski, Milosz; Comesaña-Hermo, Miguel; Correa-Duarte, Miguel Ángel; Mariñas-Pardo, Luis; Hermida-Prieto, Manuel

    2017-05-12

    The ability of optical coherence tomography (OCT) to visualise macrophages in vivo in coronary arteries is still controversial. We hypothesise that imaging of macrophages in OCT could be enhanced by means of superparamagnetic nanoparticles. We compared the optical backscattering and attenuation of cell pellets containing RAW 264.7 macrophages with those of macrophagic cell pellets labelled with very small superparamagnetic oxydised nanoparticles (VSOP) by means of light intensity analysis in OCT. The labelled macrophages were incubated with VSOP at a concentration of 1 mM Fe, corresponding to intracellular iron concentrations of 8.8 pg/cell. To study the effect of intracellular accumulation on the backscattering, VSOP dilutions without cells were also compared. OCT pullbacks of the PCR tubes containing the cell pellets were obtained and light intensity analysis was performed on raw OCT images in polar view, after normalisation by the backscattering of the PCR tube. The backscattering was estimated by the peak normalised intensity, whilst the attenuation was estimated by the number of pixels between the peak and the normalised intensity 1 (peak-to-one). VSOP-loaded macrophages have higher backscattering than the corresponding unlabelled macrophages (peak normalised intensity 6.30 vs. 3.15) with also slightly higher attenuation (peak-to-one 61 vs. 66 pixels). The backscattering of the nanoparticles in suspension was negligible in the light intensity analysis. VSOP increase significantly the optical backscattering of macrophages in the near-infrared region, with minimal increase in signal attenuation. This finding enables the enhancement of macrophages in conventional OCT imaging with an easily implementable methodology.

  7. A morphological study of retinal changes in unilateral amblyopia using optical coherence tomography image segmentation.

    Directory of Open Access Journals (Sweden)

    Andrea Szigeti

    Full Text Available OBJECTIVE: The purpose of this study was to evaluate the possible structural changes of the macula in patients with unilateral amblyopia using optical coherence tomography (OCT image segmentation. PATIENTS AND METHODS: 38 consecutive patients (16 male; mean age 32.4±17.6 years; range 6-67 years with unilateral amblyopia were involved in this study. OCT examinations were performed with a time-domain OCT device, and a custom-built OCT image analysis software (OCTRIMA was used for OCT image segmentation. The axial length (AL was measured by a LenStar LS 900 device. Macular layer thickness, AL and manifest spherical equivalent refraction (MRSE of the amblyopic eye were compared to that of the fellow eye. We studied if the type of amblyopia (strabismus without anisometropia, anisometropia without strabismus, strabismus with anisometropia had any influence on macular layer thickness values. RESULTS: There was significant difference between the amblyopic and fellow eyes in MRSE and AL in all subgroups. Comparing the amblyopic and fellow eyes, we found a statistically significant difference only in the thickness of the outer nuclear layer in the central region using linear mixed model analysis keeping AL and age under control (p = 0.032. There was no significant difference in interocular difference in the thickness of any macular layers between the subgroups with one-way between-groups ANCOVA while statistically controlling for interocular difference in AL and age. CONCLUSIONS: According to our results there are subtle changes in amblyopic eyes affecting the outer nuclear layer of the fovea suggesting the possible involvement of the photoreceptors. However, further studies are warranted to support this hypothesis.

  8. Optical Coherence Tomography and Magnetic Resonance Imaging in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder

    Science.gov (United States)

    Manogaran, Praveena; Hanson, James V. M.; Olbert, Elisabeth D.; Egger, Christine; Wicki, Carla; Gerth-Kahlert, Christina; Landau, Klara; Schippling, Sven

    2016-01-01

    Irreversible disability in multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) is largely attributed to neuronal and axonal degeneration, which, along with inflammation, is one of the major pathological hallmarks of these diseases. Optical coherence tomography (OCT) is a non-invasive imaging tool that has been used in MS, NMOSD, and other diseases to quantify damage to the retina, including the ganglion cells and their axons. The fact that these are the only unmyelinated axons within the central nervous system (CNS) renders the afferent visual pathway an ideal model for studying axonal and neuronal degeneration in neurodegenerative diseases. Structural magnetic resonance imaging (MRI) can be used to obtain anatomical information about the CNS and to quantify evolving pathology in MS and NMOSD, both globally and in specific regions of the visual pathway including the optic nerve, optic radiations and visual cortex. Therefore, correlations between brain or optic nerve abnormalities on MRI, and retinal pathology using OCT, may shed light on how damage to one part of the CNS can affect others. In addition, these imaging techniques can help identify important differences between MS and NMOSD such as disease-specific damage to the visual pathway, trans-synaptic degeneration, or pathological changes independent of the underlying disease process. This review focuses on the current knowledge of the role of the visual pathway using OCT and MRI in patients with MS and NMOSD. Emphasis is placed on studies that employ both MRI and OCT to investigate damage to the visual system in these diseases. PMID:27854301

  9. Optical Coherence Tomography and Magnetic Resonance Imaging in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder

    Directory of Open Access Journals (Sweden)

    Praveena Manogaran

    2016-11-01

    Full Text Available Irreversible disability in multiple sclerosis (MS and neuromyelitis optica spectrum disorder (NMOSD is largely attributed to neuronal and axonal degeneration, which, along with inflammation, is one of the major pathological hallmarks of these diseases. Optical coherence tomography (OCT is a non-invasive imaging tool that has been used in MS, NMOSD, and other diseases to quantify damage to the retina, including the ganglion cells and their axons. The fact that these are the only unmyelinated axons within the central nervous system (CNS renders the afferent visual pathway an ideal model for studying axonal and neuronal degeneration in neurodegenerative diseases. Structural magnetic resonance imaging (MRI can be used to obtain anatomical information about the CNS and to quantify evolving pathology in MS and NMOSD, both globally and in specific regions of the visual pathway including the optic nerve, optic radiations and visual cortex. Therefore, correlations between brain or optic nerve abnormalities on MRI, and retinal pathology using OCT, may shed light on how damage to one part of the CNS can affect others. In addition, these imaging techniques can help identify important differences between MS and NMOSD such as disease-specific damage to the visual pathway, trans-synaptic degeneration, or pathological changes independent of the underlying disease process. This review focuses on the current knowledge of the role of the visual pathway using OCT and MRI in patients with MS and NMOSD. Emphasis is placed on studies that employ both MRI and OCT to investigate damage to the visual system in these diseases.

  10. MO-F-CAMPUS-I-03: Tissue Equivalent Material Phantom to Test and Optimize Coherent Scatter Imaging for Tumor Classification

    Energy Technology Data Exchange (ETDEWEB)

    Albanese, K; Morris, R; Lakshmanan, M; Greenberg, J; Kapadia, A [Duke University, Durham, NC (United States)

    2015-06-15

    Purpose: To accurately model different breast geometries using a tissue equivalent phantom, and to classify these tissues in a coherent x-ray scatter imaging system. Methods: A breast phantom has been designed to assess the capability of coded aperture coherent x-ray scatter imaging system to classify different types of breast tissue (adipose, fibroglandular, tumor). The tissue-equivalent phantom was modeled as a hollow plastic cylinder containing multiple cylindrical and spherical inserts that can be positioned, rearranged, or removed to model different breast geometries. Each enclosure can be filled with a tissue-equivalent material and excised human tumors. In this study, beef and lard, placed inside 2-mm diameter plastic Nalgene containers, were used as surrogates for fibroglandular and adipose tissue, respectively. The phantom was imaged at 125 kVp, 40 mA for 10 seconds each with a 1-mm pencil beam. The raw data were reconstructed using a model-based reconstruction algorithm and yielded the location and form factor, or momentum transfer (q) spectrum of the materials that were imaged. The measured material form factors were then compared to the ground truth measurements acquired by x-ray diffraction (XRD) imaging. Results: The tissue equivalent phantom was found to accurately model different types of breast tissue by qualitatively comparing our measured form factors to those of adipose and fibroglandular tissue from literature. Our imaging system has been able to define the location and composition of the various materials in the phantom. Conclusion: This work introduces a new tissue equivalent phantom for testing and optimization of our coherent scatter imaging system for material classification. In future studies, the phantom will enable the use of a variety of materials including excised human tissue specimens in evaluating and optimizing our imaging system using pencil- and fan-beam geometries. United States Department of Homeland Security Duke University

  11. Beamline Design and Instrumentation for the Imaging and Coherence Beamline I13L at the Diamond Light Source

    Science.gov (United States)

    Wagner, U. H.; Pešić, Z. D.; De Fanis, A.; Rau, C.

    2013-03-01

    I13L is a 250 m long hard x-ray beamline (6 keV to 35 keV) at the Diamond Light Source. The beamline comprises of two independent experimental endstations: one for imaging in direct space using x-ray microscopy and one for imaging in reciprocal space using coherent diffraction based imaging techniques. In this paper we will discuss the fundamental design concepts of the beamline and explain their implications for the civil engineering of the endstation building and the beamline instrumentation. For the latter this paper will focus on the beamline mirror systems and monochromators.

  12. Tri-band optical coherence tomography for lipid and vessel spectroscopic imaging

    Science.gov (United States)

    Yu, Luoqin; Kang, Jiqiang; Wang, Xie; Wei, Xiaoming; Chan, Kin-Tak; Lee, Nikki P.; Wong, Kenneth K. Y.

    2016-03-01

    Optical coherence tomography (OCT) has been utilized for various functional imaging applications. One of its highlights comes from spectroscopic imaging, which can simultaneously obtain both morphologic and spectroscopic information. Assisting diagnosis and therapeutic intervention of coronary artery disease is one of the major directions in spectroscopic OCT applications. Previously Tanaka et al. have developed a spectral domain OCT (SDOCT) to image lipid distribution within blood vessel [1]. In the meantime, Fleming et al. have demonstrated optical frequency domain imaging (OFDI) by a 1.3-μm swept source and quadratic discriminant analysis model [2]. However, these systems suffered from burdensome computation as the optical properties' variation was calculated from a single-band illumination that provided limited contrast. On the other hand, multi-band OCT facilitates contrast enhancement with separated wavelength bands, which further offers an easier way to distinguish different materials. Federici and Dubois [3] and Tsai and Chan [4] have demonstrated tri-band OCT systems to further enhance the image contrast. However, these previous work provided under-explored functional properties. Our group has reported a dual-band OCT system based on parametrically amplified Fourier domain mode-locked (FDML) laser with time multiplexing scheme [5] and a dual-band FDML laser OCT system with wavelength-division multiplexing [6]. Fiber optical parametric amplifier (OPA) can be ideally incorporated in multi-band spectroscopic OCT system as it has a broad amplification window and offers an additional output range at idler band, which is phase matched with the signal band. The sweeping ranges can thus overcome traditional wavelength bands that are limited by intra-cavity amplifiers in FDML lasers. Here, we combines the dual-band FDML laser together with fiber OPA, which consequently renders a simultaneous tri-band output at 1.3, 1.5, and 1.6 μm, for intravascular applications

  13. Phase variance optical coherence microscopy for label-free imaging of the developing vasculature in zebrafish embryos

    Science.gov (United States)

    Chen, Yu; Trinh, Le A.; Fingler, Jeff; Fraser, Scott E.

    2016-12-01

    A phase variance optical coherence microscope (pvOCM) has been created to image blood flow in the microvasculature of zebrafish embryos, without the use of exogenous labels. The pvOCM imaging system has axial and lateral resolutions of 2.8 μm in tissue and imaging depth of more than 100 μm. Images of 2 to 5 days postfertilization zebrafish embryos identified the detailed anatomical structure based on OCM intensity contrast. Phase variance contrast offered visualization of blood flow in the arteries, veins, and capillaries. The pvOCM images of the vasculature were confirmed by direct comparisons with fluorescence microscopy images of transgenic embryos in which the vascular endothelium is labeled with green fluorescent protein. The ability of pvOCM to capture activities of regional blood flow permits it to reveal functional information that is of great utility for the study of vascular development.

  14. KOTOBUKI-1 apparatus for cryogenic coherent X-ray diffraction imaging

    Energy Technology Data Exchange (ETDEWEB)

    Nakasako, Masayoshi; Takayama, Yuki; Oroguchi, Tomotaka; Sekiguchi, Yuki; Kobayashi, Amane [Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148 (Japan); Shirahama, Keiya [Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Yamamoto, Masaki; Hikima, Takaaki; Yonekura, Koji; Maki-Yonekura, Saori; Kohmura, Yoshiki; Inubushi, Yuichi [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148 (Japan); Takahashi, Yukio; Suzuki, Akihiro [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148 (Japan); Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Matsunaga, Sachihiro; Inui, Yayoi [Department of Applied Biological Science Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Tono, Kensuke; Kameshima, Takashi; Joti, Yasumasa [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan); Hoshi, Takahiko [Kohzu Precision Co., Ltd., 2-6-15 Kurigi, Aso-ku, Kawasaki, Kanagawa 215-8521 (Japan)

    2013-09-15

    We have developed an experimental apparatus named KOTOBUKI-1 for use in coherent X-ray diffraction imaging experiments of frozen-hydrated non-crystalline particles at cryogenic temperature. For cryogenic specimen stage with small positional fluctuation for a long exposure time of more than several minutes, we here use a cryogenic pot cooled by the evaporation cooling effect for liquid nitrogen. In addition, a loading device is developed to bring specimens stored in liquid nitrogen to the specimen stage in vacuum. The apparatus allows diffraction data collection for frozen-hydrated specimens at 66 K with a positional fluctuation of less than 0.4 μm and provides an experimental environment to easily exchange specimens from liquid nitrogen storage to the specimen stage. The apparatus was developed and utilized in diffraction data collection of non-crystalline particles with dimensions of μm from material and biological sciences, such as metal colloid particles and chloroplast, at BL29XU of SPring-8. Recently, it has been applied for single-shot diffraction data collection of non-crystalline particles with dimensions of sub-μm using X-ray free electron laser at BL3 of SACLA.

  15. High-resolution imaging diagnosis of human fetal membrane by three-dimensional optical coherence tomography

    Science.gov (United States)

    Ren, Hugang; Avila, Cecilia; Kaplan, Cynthia; Pan, Yingtian

    2011-11-01

    Microscopic chorionic pseudocyst (MCP) arising in the chorion leave of the human fetal membrane (FM) is a clinical precursor for preeclampsia which may progress to fatal medical conditions (e.g., abortion) if left untreated. To examine the utility of three-dimensional (3D) optical coherence tomography (OCT) for noninvasive delineation of the morphology of human fetal membranes and early clinical detection of MCP, 60 human FM specimens were acquired from 10 different subjects undergoing term cesarean delivery for an ex vivo feasibility study. Our results showed that OCT was able to identify the four-layer architectures of human FMs consisting of high-scattering decidua vera (DV, average thickness dDV ~ 92+/-38 μm), low-scattering chorion and trophoblast (CT, dCT ~ 150+/-67 μm), high-scattering subepithelial amnion (A, dA ~ 95+/-36 μm), and low-scattering epithelium (E, dE ~ 29+/-8 μm). Importantly, 3D OCT was able to instantaneously detect MCPs (low scattering due to edema, fluid buildup, vasodilatation) and track (staging) their thicknesses dMCP ranging from 24 to 615 μm. It was also shown that high-frequency ultrasound was able to compliment OCT for detecting more advanced thicker MCPs (e.g., dMCP>615 μm) because of its increased imaging depth.

  16. Real-time imaging of suction blistering in human skin using optical coherence tomography

    Science.gov (United States)

    Carvalho, Joana C.O.; Palero, Jonathan A.; Jurna, Martin

    2015-01-01

    Separation of skin epidermis from the dermis by suction blistering has been used with high success rate for autologous skin epidermal grafting in burns, chronic wounds and vitiligo transplantation treatment. Although commercial products that achieve epidermal grafting by suction blistering are presently available, there is still limited knowledge and understanding on the dynamic process of epidermal-dermal separation during suction blistering. In this report we integrated a suction system to an Optical Coherence Tomography (OCT) which allowed for the first time, real-time imaging of the suction blistering process in human skin. We describe in this report the evolution of a suction blister where the growth is modeled with a Boltzmann sigmoid function. We further investigated the relationship between onset and steady-state blister times, blister growth rate, applied suction pressure and applied local skin temperature. Our results show that while the blister time is inversely proportional to the applied suction pressure, the relationship between the blister time and the applied temperature is described by an exponential decay. PMID:26713194

  17. Noncontact quantitative biomechanical characterization of cardiac muscle using shear wave imaging optical coherence tomography.

    Science.gov (United States)

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

    2014-07-01

    We report on a quantitative optical elastographic method based on shear wave imaging optical coherence tomography (SWI-OCT) for biomechanical characterization of cardiac muscle through noncontact elasticity measurement. The SWI-OCT system employs a focused air-puff device for localized loading of the cardiac muscle and utilizes phase-sensitive OCT to monitor the induced tissue deformation. Phase information from the optical interferometry is used to reconstruct 2-D depth-resolved shear wave propagation inside the muscle tissue. Cross-correlation of the displacement profiles at various spatial locations in the propagation direction is applied to measure the group velocity of the shear waves, based on which the Young's modulus of tissue is quantified. The quantitative feature and measurement accuracy of this method is demonstrated from the experiments on tissue-mimicking phantoms with the verification using uniaxial compression test. The experiments are performed on ex vivo cardiac muscle tissue from mice with normal and genetically altered myocardium. Our results indicate this optical elastographic technique is useful as a noncontact tool to assist the cardiac muscle studies.

  18. Choroid thickness in central serous chorioretinopathy using enhanced depth imaging optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Xiao-Long Yu

    2013-04-01

    Full Text Available AIM: To observe the choroidal thickness in the macular area in affected and unaffected fellow eyes with central serous chorio retinopathy(CSCand in healthy controls. METHODS: Twenty-six cases with unilateral CSC and controls were recruited in this study. All eyes were divided into three groups: 26 eyes in Group A(affected eyes with CSC, 26 eyes in group B(unaffected fellow eyesand 26 eyes in group C(right eyes of age and sex matched control. Enhanced depth imaging was obtained by using spectral-domain optical coherence tomography. Subfoveal choroidal thickness and choroidal thickness at 1mm/3mm nasal, temporal, superior and inferior to the fovea were measured. RESULTS: Choroidal thickness was significantly increased in affected eyes with CSC than unaffected fellow eyes(t=5.57, P<0.01.The mean subfoveal choroidal thickness(SFCTwas 528.31±91.24μm in group A, 413.71±79.35μm in group B, and 301.31±52.46 in group C. The subfoveal choroid was significantly thicker in group A than Group C(P<0.01. SFCT in unaffected fellow eyes were thicker than the controls(P<0.01. CONCLUSION:Choroidal thickness is thicker in affected eyes with CSC and also in fellow unaffected eyes, indicating that the choroid blood vessels are high and perfusion state, may be one of the factors of the disease CSC.

  19. Repeatability of Choroidal Thickness Measurements on Enhanced Depth Imaging Optical Coherence Tomography Using Different Posterior Boundaries.

    Science.gov (United States)

    Vuong, Vivian S; Moisseiev, Elad; Cunefare, David; Farsiu, Sina; Moshiri, Ala; Yiu, Glenn

    2016-09-01

    To assess the reliability of manual choroidal thickness measurements by comparing different posterior boundary definitions of the choroidal-scleral junction on enhanced depth imaging optical coherence tomography (EDI-OCT). Reliability analysis. Two graders marked the choroidal-scleral junction with segmentation software using different posterior boundaries: (1) the outer border of the choroidal vessel lumen, (2) the outer border of the choroid stroma, and (3) the inner border of the sclera, to measure the vascular choroidal thickness (VCT), stromal choroidal thickness (SCT), and total choroidal thickness (TCT), respectively. Measurements were taken at 0.5-mm intervals from 1.5 mm nasal to 1.5 mm temporal to the fovea, and averaged continuously across the central 3 mm of the macula. Intraclass correlation coefficient (ICC) and coefficient of reliability (CR) were compared to assess intergrader and intragrader reliability. Choroidal thickness measurements varied significantly with different posterior boundaries (P choroidal-scleral junction visibility was Choroidal thickness measurements are more reproducible when measured to the border of the choroid stroma (SCT) than the vascular lumen (VCT) or sclera (TCT). Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Development of a first-generation miniature multiple reference optical coherence tomography imaging device

    Science.gov (United States)

    McNamara, Paul M.; Dsouza, Roshan; O'Riordan, Colm; Collins, Seán; O'Brien, Peter; Wilson, Carol; Hogan, Josh; Leahy, Martin J.

    2016-12-01

    Multiple reference optical coherence tomography (MR-OCT) is a technology ideally suited to low-cost, compact OCT imaging. This modality is an extension of time-domain OCT with the addition of a partial mirror in front of the reference mirror. This enables extended, simultaneous depth scanning with the relatively short scan range of a miniature voice coil motor on which the scanning mirror is mounted. This work details early stage development of the first iteration of a miniature MR-OCT device. This iteration utilizes a fiber-coupled input from an off-board superluminescent diode. The dimensions of the module are 40×57 mm. Off-the-shelf miniature optical components, voice coil motors, and photodetectors are used, with the complexity of design depending on the specific application. The photonic module can be configured as either polarized or nonpolarized and can include balanced detection. The results shown in this work are from the nonpolarized device. The system was characterized through measurement of the input spectrum, axial resolution, and signal-to-noise ratio. Typical B-scans of static and in vivo samples are shown, which illustrate the potential applications for such a technology.

  1. An all-fiber image-reject homodyne coherent Doppler wind lidar.

    Science.gov (United States)

    Abari, Cyrus F; Pedersen, Anders T; Mann, Jakob

    2014-10-20

    In this paper, we present an alternative approach to the down-conversion (translation) of the received optical signals collected by the antenna of an all-fiber coherent Doppler lidar (CDL). The proposed method, widely known as image-reject, quadrature detection, or in-phase/quadrature-phase detection, utilizes the advances in fiber optic communications such that the received signal can be optically down-converted into baseband where not only the radial velocity but also the direction of the movement can be inferred. In addition, we show that by performing a cross-spectral analysis, enabled by the presence of two independent signal observations with uncorrelated noise, various noise sources can be suppressed and a more simplified velocity estimation algorithm can be employed in the spectral domain. Other benefits of this architecture include, but are not limited to, a more reliable measurement of radial velocities close to zero and an improved bandwidth. The claims are verified through laboratory implementation of a continuous wave CDL, where measurements both on a hard and diffuse target have been performed and analyzed.

  2. Influence of spatial and temporal coherences on atomic resolution high angle annular dark field imaging.

    Science.gov (United States)

    Beyer, Andreas; Belz, Jürgen; Knaub, Nikolai; Jandieri, Kakhaber; Volz, Kerstin

    2016-10-01

    Aberration-corrected (scanning) transmission electron microscopy ((S)TEM) has become a widely used technique when information on the chemical composition is sought on an atomic scale. To extract the desired information, complementary simulations of the scattering process are inevitable. Often the partial spatial and temporal coherences are neglected in the simulations, although they can have a huge influence on the high resolution images. With the example of binary gallium phosphide (GaP) we elucidate the influence of the source size and shape as well as the chromatic aberration on the high angle annular dark field (HAADF) intensity. We achieve a very good quantitative agreement between the frozen phonon simulation and experiment for different sample thicknesses when a Lorentzian source distribution is assumed and the effect of the chromatic aberration is considered. Additionally the influence of amorphous layers introduced by the preparation of the TEM samples is discussed. Taking into account these parameters, the intensity in the whole unit cell of GaP, i.e. at the positions of the different atomic columns and in the region between them, is described correctly. With the knowledge of the decisive parameters, the determination of the chemical composition of more complex, multinary materials becomes feasible.

  3. Aspect sensitivity measurements of polar mesosphere summer echoes using coherent radar imaging

    Directory of Open Access Journals (Sweden)

    P. B. Chilson

    Full Text Available The Esrange VHF radar (ESRAD, located in northern Sweden (67.88° N, 21.10° E, has been used to investigate polar mesosphere summer echoes (PMSE. During July and August of 1998, coherent radar imaging (CRI was used to study the dynamic evolution of PMSE with high temporal and spatial resolution. A CRI analysis provides an estimate of the angular brightness distribution within the radar’s probing volume. The brightness distribution is directly related to the radar reflectivity. Consequently, these data are used to investigate the aspect sensitivity of PMSE. In addition to the CRI analysis, the full correlation analysis (FCA is used to derive estimates of the prevailing three-dimensional wind associated with the observed PMSE. It is shown that regions within the PMSE with enhanced aspect sensitivity have a correspondingly high signal-to-noise ratio (SNR. Although this relationship has been investigated in the past, the present study allows for an estimation of the aspect sensitivity independent of the assumed scattering models and avoids the complications of comparing echo strengths from vertical and off-vertical beams over large horizontal separations, as in the Doppler Beam Swinging (DBS method. Regions of enhanced aspect sensitivity were additionally shown to correlate with the wave-perturbation induced downward motions of air parcels embedded in the PMSE.

    Key words. Ionosphere (polar ionosphere Meteorology and Atmospheric Dynamics (middle atmosphere dynamics Radio Science (Interferometry

  4. Geometric considerations of polar mesospheric summer echoes in tilted beams using coherent radar imaging

    Science.gov (United States)

    Sommer, S.; Stober, G.; Chau, J. L.; Latteck, R.

    2014-11-01

    We present observations of polar mesospheric summer echoes (PMSE) using the Middle Atmosphere Alomar Radar System in Northern Norway (69.30° N, 16.04° E). The radar is able to resolve PMSE at high spatial and temporal resolution and to perform pulse-to-pulse beam steering. In this experiment, 81 oblique beam directions were used with off-zenith angles up to 25°. For each beam pointing direction and range gate, coherent radar imaging was applied to determine the mean backscatter location. The location of the mean scatterer in the beam volume was calculated by the deviation from the nominal off-zenith angle of the brightest pixel. It shows that in tilted beams with an off-zenith angle greater than 5°, structures appear at the altitudinal edges of the PMSE layer. Our results indicate that the mean influence of the location of the maximum depends on the tilt of the beam and on the observed area of the PMSE layer. At the upper/lower edge of the PMSE layer, the mean backscatter has a greater/smaller off-zenith angle than the nominal off-zenith angle. This effect intensifies with greater off-zenith beam pointing direction, so the beam filling factor plays an important role in the observation of PMSE layers for oblique beams.

  5. Choroidal structure determined by binarizing optical coherence tomography images in eyes with reticular pseudodrusen

    Directory of Open Access Journals (Sweden)

    Masuda N

    2017-04-01

    Full Text Available Naonori Masuda, Masashi Kojima, Mariko Yamashita, Tomo Nishi, Nahoko Ogata Department of Ophthalmology, Nara Medical University, Nara, Japan Purpose: To compare the choroidal structure beneath the macular area in eyes with reticular pseudodrusen (RPD and age-matched controls.Methods: This study was performed at Nara Medical University Hospital, Japan. Twenty eyes of 14 patients (82.3±4.2 years, mean ± standard deviation with RPD and 35 eyes of 20 age-matched controls (81.5±6.0 years were studied. The choroidal structure was determined by binarizing the images obtained by enhanced depth imaging optical coherence tomography in all patients and controls. The total, luminal, and stromal choroidal areas were quantified by the binarization method.Results: The total choroidal area of the eyes with RPD was significantly smaller than that of control eyes (P=0.001, unpaired t-test. Both the luminal and stromal areas in eyes with RPD were significantly smaller than that of control eyes (P=0.001, paired t-test, but there was no significant difference in the luminal/stromal ratio between eyes with RPD and control eyes.Conclusion: The total, luminal, and stromal choroidal areas in eyes with RPD were smaller than those of the control eyes. The reduction of the choroidal luminal and stromal areas may be due to a loss of the oxygen demand of the choroid due to RPE dysfunction. Keywords: reticular pseudodrusen, age-related macular degeneration, choroidal structure, binarization method

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

    Science.gov (United States)

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

    2016-03-01

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

  7. Optical coherence tomography image-guided smart laser knife for surgery.

    Science.gov (United States)

    Katta, Nitesh; McElroy, Austin B; Estrada, Arnold D; Milner, Thomas E

    2017-08-07

    Surgical oncology can benefit from specialized tools that enhance imaging and enable precise cutting and removal of tissue without damage to adjacent structures. The combination of high-resolution, fast optical coherence tomography (OCT) co-aligned with a nanosecond pulsed thulium (Tm) laser offers advantages over conventional surgical laser systems. Tm lasers provide superior beam quality, high volumetric tissue removal rates with minimal residual thermal footprint in tissue, enabling a reduction in unwanted damage to delicate adjacent sub-surface structures such as nerves or micro-vessels. We investigated such a combined Tm/OCT system with co-aligned imaging and cutting beams-a configuration we call a "smart laser knife." A blow-off model that considers absorption coefficients and beam delivery systems was utilized to predict Tm cut depth, tissue removal rate and spatial distribution of residual thermal injury. Experiments were performed to verify the volumetric removal rate predicted by the model as a function of average power. A bench-top, combined Tm/OCT system was constructed using a 15W 1940 nm nanosecond pulsed Tm fiber laser (500 μJ pulse energy, 100 ns pulse duration, 30 kHz repetition rate) for removing tissue and a swept source laser (1310 ± 70 nm, 100 kHz sweep rate) for OCT imaging. Tissue phantoms were used to demonstrate precise surgery with blood vessel avoidance. Depth imaging informed cutting/removal of targeted tissue structures by the Tm laser was performed. Laser cutting was accomplished around and above phantom blood vessels while avoiding damage to vessel walls. A tissue removal rate of 5.5 mm(3) /sec was achieved experimentally, in comparison to the model prediction of approximately 6 mm(3) /sec. We describe a system that combines OCT and laser tissue modification with a Tm laser. Simulation results of the tissue removal rate using a simple model, as a function of average power, are in good agreement with experimental

  8. Optical coherence tomography: influence of contrast concentration on image quality and diagnostic confidence.

    Science.gov (United States)

    Blachutzik, Florian; Achenbach, Stephan; Nef, Holger; Hamm, Christian; Dörr, Oliver; Boeder, Niklas; Marwan, Mohamed; Tröbs, Monique; Schneider, Reinhard; Röther, Jens; Schlundt, Christian

    2016-11-09

    OCT requires intracoronary injection of contrast agent to remove blood from the coronary lumen during data acquisition, which is a possible limitation of this method. Aim of this study was to analyze the influence of iodine concentration on image quality and diagnostic certainty of optical coherence tomography (OCT). OCT sequences acquired using contrast agent with a reduced concentration of 150 mg iodine/ml and a standard concentration of 350 mg iodine/ml were analyzed. Cross-sectional images with a spacing of 10 mm were evaluated regarding image quality and diagnostic confidence. A total of 67 OCT sequences acquired in 24 patients were analyzed. 31 sequences were acquired using contrast agent with a concentration of 150 mg iodine/ml and 36 sequences with a concentration of 350 mg iodine/ml. The percentage of remaining blood streaks in the cross sections was significantly lower for 350 mg iodine/ml compared to 150 mg iodine/ml (19 ± 21 vs. 34 ± 26%, p = 0.013). Contrast with 350 mg iodine/ml showed a significantly higher percentage of completely flushed pullback length as compared to 150 mg iodine/ml (78 ± 24 vs. 58 ± 27%, p = 0.004). Diagnostic certainty was significantly higher for 350 mg iodine/ml than for 150 mg iodine/ml (Likert scale average 1.4 ± 0.7 vs. 2.1 ± 1.2, p < 0.001; Likert scale: 1 = absolutely confident, 2 = confident with slight doubts, 3 = doubtful/not confident, 4 = non-diagnostic). Regarding image quality and diagnostic certainty, contrast agent with a concentration of 350 mg iodine/ml is superior to 150 mg iodine/ml.

  9. In-vivo imaging of blood flow in human retinal vessels using color Doppler optical coherence tomography

    Science.gov (United States)

    Yazdanfar, Siavash; Rollins, Andrew M.; Izatt, Joseph A.

    1999-04-01

    Quantification of retinal blood flow may lead to a better understanding of the progression and treatment of several ocular disorders, including diabetic retinopathy, age- related macular degeneration, and glaucoma. Current techniques, such as fluorescein angiography and laser Doppler velocimetry are limited, failing to provide sufficient information to the clinician. Color Doppler optical coherence tomography (CDOCT) is a novel technique using coherent heterodyne detection for simultaneous cross- sectional imaging of tissue microstructure and blood flow. This technique is capable of high spatial and velocity resolution imaging in highly scattering media. We implemented CDOCT for retinal blood flow mapping in human subjects. No dilation of the pupil was necessary. CDOCT is demonstrated for determining bidirectional flow in sub- 100micrometers diameter vessels in the retina. Additionally, we calculated Doppler broadening using the variance of depth- resolved spectra to identify regions with large velocity gradients within the Xenopus heart. This technique may be useful in quantifying local tissue perfusion in highly vascular retinal tissue.

  10. Preliminary results on in-vivo imaging of upper airway inhalation injuries using anatomical optical coherence tomography

    Science.gov (United States)

    Phan, Anthony; Karnowski, Karol; Lee, Qingyun; Fejes, Peter; Quirk, Bryden; McLaughlin, Robert; Wood, Fiona M.; Sampson, David D.

    2017-04-01

    Quantitative assessment of upper airway geometry using optical coherence tomography in burns patients could provide physicians with the information needed to make critical decisions. We have developed a high speed catheter based OCT system capable of real time imaging in airways up to 3cm in diameter. Preliminary scans of inhalation injured airways are presented to demonstrate the feasibility of aOCT as a diagnostic tool for assessing burns patients.

  11. Instability of Solution of Phase Retrieval in Direct Diffraction Phase-Contrast Imaging with Partially Coherent X-Ray Source

    Institute of Scientific and Technical Information of China (English)

    GUO Hua; HAN Shen-Sheng

    2006-01-01

    The theoretical model of direct diffraction phase-contrast imaging with partially coherent x-ray source is expressedby an operator of multiple integral. It is presented that the integral operator is linear. The problem of its phaseretrieval is described by solving an operator equation of multiple integral. It is demonstrated that the solution ofthe phase retrieval is unstable. The numerical simulation is performed and the result validates that the solutionof the phase retrieval is unstable.

  12. Three dimensional time lapse imaging of live cell mitochondria with photothermal optical lock-in optical coherence microscopy (Conference Presentation)

    Science.gov (United States)

    Sison, Miguel; Chakrabortty, Sabyasachi; Extermann, Jerome; Nahas, Amir; Pache, Christophe; Weil, Tanja; Lasser, Theo

    2016-03-01

    The photothermal optical lock-in optical coherence microscope (poli-OCM) introduced molecular specificity to OCM imaging, which is conventionally, a label-free technique. Here we achieve three-dimensional live cell and mitochondria specific imaging using ~4nm protein-functionalized gold nanoparticles (AuNPs). These nanoparticles do not photobleach and we demonstrate they're suitability for long-term time lapse imaging. We compare the accuracy of labelling with these AuNPs using classical fluorescence confocal imaging with a standard mitochondria specific marker. Furthermore, time lapse poli-OCM imaging every 5 minutes over 1.5 hours period was achieved, revealing the ability for three-dimensional monitoring of mitochondria dynamics.

  13. Comparison of optical coherence tomography, microcomputed tomography, and histology at a three-dimensionally imaged trabecular bone sample

    Science.gov (United States)

    Kasseck, Christoph; Kratz, Marita; Torcasio, Antonia; Gerhardt, Nils C.; van Lenthe, G. Harry; Gambichler, Thilo; Hoffmann, Klaus; Jones, David B.; Hofmann, Martin R.

    2010-07-01

    We investigate optical coherence tomography (OCT) as a method for imaging bone. The OCT images are compared directly to those of the standard methods of bone histology and microcomputed tomography (μCT) on a single, fixed human femoral trabecular bone sample. An advantage of OCT over bone histology is its noninvasive nature. OCT also images the lamellar structure of trabeculae at slightly higher contrast than normal bone histology. While μCT visualizes the trabecular framework of the whole sample, OCT can image additionally cells with a penetration depth limited approximately to 1 mm. The most significant advantage of OCT, however, is the absence of toxic effects (no ionizing radiation), i.e., continuous images may be made and individual cell tracking may be performed. The penetration depth of OCT, however, limits its use to small animal models and small bone organ cultures.

  14. Imaging neutrophil migration dynamics using micro-optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Chu, Kengyeh K.; Yonker, Lael; Som, Avira; Pazos, Michael; Kusek, Mark E.; Hurley, Bryan P.; Tearney, Guillermo J.

    2016-03-01

    Neutrophils are immune cells that undergo chemotaxis, detecting and migrating towards a chemical signal gradient. Neutrophils actively migrate across epithelial boundaries, interacting with the epithelium to selectively permit passage without compromising the epithelial barrier. In many inflammatory disorders, excessive neutrophil migration can cause damage to the epithelium itself. The signaling pathways and mechanisms that facilitate trans-epithelial migration are not fully characterized. Our laboratory has developed micro-optical coherence tomography (μOCT), which has 2 μm lateral resolution and 1 μm axial resolution. As a high-resolution native contrast modality, μOCT can directly visualize individual neutrophils as they interact with a cell layer cultured on a transwell filter. A chemoattractant can be applied to the apical side of inverted monolayer, and human neutrophils placed in the basolateral compartment, while μOCT captures 3D images of the chemotaxis. μOCT images can also generate quantitative metrics of migration volume to study the dependence of chemotaxis on monolayer cell type, chemoattractant type, and disease state of the neutrophils. For example, a disease known as leukocyte adhesion deficiency (LAD) can be simulated by treating neutrophils with antibodies that interfere with the CD18 receptor, a facilitator of trans-epithelial migration. We conducted a migration study of anti-CD18 treated and control neutrophils using T84 intestinal epithelium as a barrier. After one hour, μOCT time-lapse imaging indicated a strong difference in the fraction of neutrophils that remain attached to the epithelium after migration (0.67 +/- 0.12 attached anti-CD18 neutrophils, 0.23 +/- 0.08 attached control neutrophils, n = 6, p < 0.05), as well as a modest but non-significant decrease in total migration volume for treated neutrophils. We can now integrate μOCT-derived migration metrics with simultaneously acquired measurements of transepithelial electrical

  15. Enhanced vitreous imaging in healthy eyes using swept source optical coherence tomography.

    Directory of Open Access Journals (Sweden)

    Jonathan J Liu

    Full Text Available To describe enhanced vitreous imaging for visualization of anatomic features and microstructures within the posterior vitreous and vitreoretinal interface in healthy eyes using swept-source optical coherence tomography (SS-OCT. The study hypothesis was that long-wavelength, high-speed, volumetric SS-OCT with software registration motion correction and vitreous window display or high-dynamic-range (HDR display improves detection sensitivity of posterior vitreous and vitreoretinal features compared to standard OCT logarithmic scale display.Observational prospective cross-sectional study.Multiple wide-field three-dimensional SS-OCT scans (500×500A-scans over 12×12 mm2 were obtained using a prototype instrument in 22 eyes of 22 healthy volunteers. A registration motion-correction algorithm was applied to compensate motion and generate a single volumetric dataset. Each volumetric dataset was displayed in three forms: (1 standard logarithmic scale display, enhanced vitreous imaging using (2 vitreous window display and (3 HDR display. Each dataset was reviewed independently by three readers to identify features of the posterior vitreous and vitreoretinal interface. Detection sensitivities for these features were measured for each display method.Features observed included the bursa premacularis (BPM, area of Martegiani, Cloquet's/BPM septum, Bergmeister papilla, posterior cortical vitreous (hyaloid detachment, papillomacular hyaloid detachment, hyaloid attachment to retinal vessel(s, and granular opacities within vitreous cortex, Cloquet's canal, and BPM. The detection sensitivity for these features was 75.0% (95%CI: 67.8%-81.1% using standard logarithmic scale display, 80.6% (95%CI: 73.8%-86.0% using HDR display, and 91.9% (95%CI: 86.6%-95.2% using vitreous window display.SS-OCT provides non-invasive, volumetric and measurable in vivo visualization of the anatomic microstructural features of the posterior vitreous and vitreoretinal interface. The

  16. Validation of coded aperture coherent scatter spectral imaging for normal and neoplastic breast tissues via surgical pathology

    Science.gov (United States)

    Morris, R. E.; Albanese, K. E.; Lakshmanan, M. N.; McCall, S. J.; Greenberg, J. A.; Kapadia, A. J.

    2016-03-01

    This study intends to validate the sensitivity and specificity of coded aperture coherent scatter spectral imaging (CACSSI) by comparison to standard histological preparation and pathologic analysis methods used to differentiate normal and neoplastic breast tissues. A composite overlay of the CACSSI rendered image and pathologist interpreted stained sections validate the ability of CACSSI to differentiate normal and neoplastic breast structures ex-vivo. Via comparison to pathologist annotated slides, the CACSSI system may be further optimized to maximize sensitivity and specificity for differentiation of breast carcinomas.

  17. Numerical simulation of partially coherent broadband optical imaging using the finite-difference time-domain method.

    Science.gov (United States)

    Çapoğlu, İlker R; White, Craig A; Rogers, Jeremy D; Subramanian, Hariharan; Taflove, Allen; Backman, Vadim

    2011-05-01

    Rigorous numerical modeling of optical systems has attracted interest in diverse research areas ranging from biophotonics to photolithography. We report the full-vector electromagnetic numerical simulation of a broadband optical imaging system with partially coherent and unpolarized illumination. The scattering of light from the sample is calculated using the finite-difference time-domain (FDTD) numerical method. Geometrical optics principles are applied to the scattered light to obtain the intensity distribution at the image plane. Multilayered object spaces are also supported by our algorithm. For the first time, numerical FDTD calculations are directly compared to and shown to agree well with broadband experimental microscopy results.

  18. Enhanced depth imaging optical coherence tomography of choroidal osteoma with secondary neovascular membranes: report of two cases

    Directory of Open Access Journals (Sweden)

    Patrícia Correa de Mello

    2016-06-01

    Full Text Available ABSTRACT We report enhanced depth imaging optical coherence tomography (EDI-OCT features based on clinical and imaging data from two newly diagnosed cases of choroidal osteoma presenting with recent visual loss secondary to choroidal neovascular membranes. The features described in the two cases, compression of the choriocapillaris and disorganization of the medium and large vessel layers, are consistent with those of previous reports. We noticed a sponge-like pattern previously reported, but it was subtle. Both lesions had multiple intralesional layers and a typical intrinsic transparency with visibility of the sclerochoroidal junction.

  19. Noise-immune complex correlation for vasculature imaging based on standard and Jones-matrix optical coherence tomography

    Science.gov (United States)

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

    2016-03-01

    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.

  20. Teleophthalmology with optical coherence tomography imaging in community optometry. Evaluation of a quality improvement for macular patients

    Directory of Open Access Journals (Sweden)

    Kelly SP

    2011-12-01

    Full Text Available Simon P Kelly1, Ian Wallwork2, David Haider1, Kashif Qureshi11Ophthalmology Department, Royal Bolton Hospital National Health Service Foundation Trust, Bolton, 2Wallwork Opticians, Salford, UKPurpose: To describe a quality improvement for referral of National Health Service patients with macular disorders from a community optometry setting in an urban area.Methods: Service evaluation of teleophthalmology consultation based on spectral domain optical coherence tomography images acquired by the community optometrist and transmitted to hospital eye services.Results: Fifty patients with suspected macular conditions were managed via telemedicine consultation over 1 year. Responses were provided by hospital eye service-based ophthalmologists to the community optometrist or patient within the next day in 48 cases (96% and in 34 (68% patients on the same day. In the consensus opinion of the optometrist and ophthalmologist, 33 (66% patients required further “face-to-face” medical examination and were triaged on clinical urgency. Seventeen cases (34% were managed in the community and are a potential cost improvement. Specialty trainees were supervised in telemedicine consultations.Conclusion: Innovation and quality improvement were demonstrated in both optometry to ophthalmology referrals and in primary optometric care by use of telemedicine with spectral domain optical coherence tomography images. E-referral of spectral domain optical coherence tomography images assists triage of macular patients and swifter care of urgent cases. Teleophthalmology is also, in the authors’ opinion, a tool to improve interdisciplinary professional working with community optometrists. Implications for progress are discussed.Keywords: telemedicine, teleophthalmology, innovation, community referral, optical coherence tomography, service evaluation

  1. Automated tissue classification of intracardiac optical coherence tomography images (Conference Presentation)

    Science.gov (United States)

    Gan, Yu; Tsay, David; Amir, Syed B.; Marboe, Charles C.; Hendon, Christine P.

    2016-03-01

    Remodeling of the myocardium is associated with increased risk of arrhythmia and heart failure. Our objective is to automatically identify regions of fibrotic myocardium, dense collagen, and adipose tissue, which can serve as a way to guide radiofrequency ablation therapy or endomyocardial biopsies. Using computer vision and machine learning, we present an automated algorithm to classify tissue compositions from cardiac optical coherence tomography (OCT) images. Three dimensional OCT volumes were obtained from 15 human hearts ex vivo within 48 hours of donor death (source, NDRI). We first segmented B-scans using a graph searching method. We estimated the boundary of each region by minimizing a cost function, which consisted of intensity, gradient, and contour smoothness. Then, features, including texture analysis, optical properties, and statistics of high moments, were extracted. We used a statistical model, relevance vector machine, and trained this model with abovementioned features to classify tissue compositions. To validate our method, we applied our algorithm to 77 volumes. The datasets for validation were manually segmented and classified by two investigators who were blind to our algorithm results and identified the tissues based on trichrome histology and pathology. The difference between automated and manual segmentation was 51.78 +/- 50.96 μm. Experiments showed that the attenuation coefficients of dense collagen were significantly different from other tissue types (P < 0.05, ANOVA). Importantly, myocardial fibrosis tissues were different from normal myocardium in entropy and kurtosis. The tissue types were classified with an accuracy of 84%. The results show good agreements with histology.

  2. Assessment of choroidal thickness of central serous chorioretinopathy by optical coherence tomography with enhanced depth imaging

    Directory of Open Access Journals (Sweden)

    Hui Hang

    2015-01-01

    Full Text Available AIM: To evaluate the meaning of using optical coherence tomography with enhanced depth imaging(OCT-EDIto measure choroidal thickness of central serous retinopathy(CSC. METHODS: With the retrospective case control study, 65 patients(65 eyeswith CSC and 50 healthy controls(50 eyeswith age, gender and diopter-matched were recruited in this study. OCT-EDI were used to measure the subfoveal choroidal thickness(SFCTin CSC eyes, the fellow eyes and also the control eyes. Of which 40 of the 65 CSC patients self-cured, 14 of them were treated with photodynamic therapy(PDT, the left 11 accepted the laser photocoagulation(LP. SFCT were measured 3mo after that. Compared with the previous data, the statistical analysis was carried out.RESULTS: The SFCT value of 65 CSC eyes, 65 fellow eyes and 50 control eyes were 436.23±89.50, 389.45±101.03 and 329.36±95.87μm, respectively. The SFCT of suffer and fellow eyes increased significantly compared to the control eyes(P=0.008 and 0.013, respectively. There was also significant difference in SFCT between the CSC eyes and the fellow eyes(P=0.021. The SFCT were significantly decreased after PDT(P=0.032, but with no significant changes after LP or self-cured(P=0.057 and 0.076, respectively.CONCLUSION: OCT-EDI is a useful method to assess the choroidal topographic changes of CSC. The SFCT are significantly increased in the CSC eyes compared with that in the fellow eyes and the control eyes.

  3. Development of a miniature multiple reference optical coherence tomography imaging device

    Science.gov (United States)

    McNamara, Paul M.; O'Riordan, Colm; Collins, Seán.; O'Brien, Peter; Wilson, Carol; Hogan, Josh; Leahy, Martin J.

    2016-03-01

    Multiple reference optical coherence tomography (MR-OCT) is a new technology ideally suited to low-cost, compact OCT imaging. This modality is an extension of time-domain OCT with the addition of a partial mirror in front of the reference mirror. This enables extended, simultaneous depth scanning with the relatively short sweep of a miniature voice coil motor on which the scanning mirror is mounted. Applications of this technology include biometric security, ophthalmology, personal health monitoring and non-destructive testing. This work details early-stage development of the first iteration of a miniature MR-OCT device. This device utilizes a fiber-coupled input from an off-board superluminescent diode (SLD). Typical dimensions of the module are 40 × 57 mm, but future designs are expected to be more compact. Off-the-shelf miniature optical components, voice coil motors and photodetectors are used, with the complexity of design depending on specific applications. The photonic module can be configured as either polarized or non-polarized and can include balanced detection. The photodetectors are directly connected to a printed circuit board under the module containing a transimpedance amplifier with complimentary outputs. The results shown in this work are from the non-polarized device. Assembly of the photonic modules requires extensive planning. In choosing the optical components, Zemax simulations are performed to model the beam characteristics. The physical layout is modeled using Solidworks and each component is placed and aligned via a well-designed alignment procedure involving an active-alignment pick-and-place assembly system.

  4. Image-guided modified deep anterior lamellar keratoplasty (DALK) corneal transplant using intraoperative optical coherence tomography

    Science.gov (United States)

    Tao, Yuankai K.; LaBarbera, Michael; Ehlers, Justis P.; Srivastava, Sunil K.; Dupps, William J.

    2015-03-01

    Deep anterior lamellar keratoplasty (DALK) is an alternative to full-thickness corneal transplant and has advantages including the absence of allograft rejection; shortened duration of topical corticosteroid treatment and reduced associated risk of glaucoma, cataract, or infection; and enables use of grafts with poor endothelial quality. DALK begins by performing a trephination of approximately 80% stromal thickness, as measured by pachymetry. After removal of the anterior stoma, a needle is inserted into the residual stroma to inject air or viscoelastic to dissect Descemet's membrane. These procedures are inherently difficult and intraoperative rates of Descemet's membrane perforation between 4-39% have been reported. Optical coherence tomography (OCT) provides high-resolution images of tissue microstructures in the cornea, including Descemet's membrane, and allows quantitation of corneal layer thicknesses. Here, we use crosssectional intraoperative OCT (iOCT) measurements of corneal thickness during surgery and a novel micrometeradjustable biopsy punch to precision-cut the stroma down to Descemet's membrane. Our prototype cutting tool allows us to establish a dissection plane at the corneal endothelium interface, mitigates variability in cut-depths as a result of tremor, reduces procedure complexity, and reduces complication rates. iOCT-guided modified DALK procedures were performed on 47 cadaveric porcine eyes by non-experts and achieved a perforation rate of ~5% with a mean corneal dissection time <18 minutes. The procedure was also successful performed on a human donor eye without perforation. Our data shows the potential for iOCT-guided precision anterior segment surgery without variability as a result of tremor and improvements to standard clinical care.

  5. Additive diagnostic role of imaging in glaucoma: optical coherence tomography and retinal nerve fiber layer photography.

    Science.gov (United States)

    Kim, Ko Eun; Kim, Seok Hwan; Oh, Sohee; Jeoung, Jin Wook; Suh, Min Hee; Seo, Je Hyun; Kim, Martha; Park, Ki Ho; Kim, Dong Myung

    2014-11-20

    To investigate the additive diagnostic role of spectral-domain optical coherence tomography (SD-OCT) and red-free retinal nerve fiber layer photography (RNFLP) in making clinical glaucoma diagnosis. Four diagnostic combination sets, including the most recent image from each measurement of 196 glaucoma eyes (including the 44 preperimetric glaucoma eyes) and 101 healthy eyes, were prepared: (1) stereo disc photography and Humphrey visual field (SH), (2) SH and SD-OCT (SHO), (3) SH and RNFLP (SHR), and (4) SHR and SD-OCT (SHRO). Each randomly sorted set was serially presented at 1-month intervals to five glaucoma specialists who were asked to evaluate them in a subjective and independent manner. The specialists' glaucoma-diagnostic performances based on the sets were then compared. For each specialist, adding SD-OCT to SH or SHR increased the glaucoma-diagnostic sensitivity but not to a level of statistical significance. For one specialist, adding RNFLP to SH significantly increased the sensitivity. Each specialist showed a high level of specificity regardless of the diagnostic set. The overall sensitivity of all specialists' assessments was significantly increased by adding RNFLP or the combination of SD-OCT and RNFLP to SH (P < 0.001); however, adding SD-OCT to SH or SHR did not significantly increase the sensitivity. A similar relationship was noted also for the preperimetric glaucoma subgroup. In contrast to RNFLP, SD-OCT did not significantly enhance the diagnostic accuracy of detecting glaucoma or even of preperimetric glaucoma. Our results suggest that, at least for glaucoma specialists, the additive diagnostic role of OCT is limited. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  6. Single-pulse enhanced coherent diffraction imaging of bacteria with an X-ray free-electron laser

    Science.gov (United States)

    Fan, Jiadong; Sun, Zhibin; Wang, Yaling; Park, Jaehyun; Kim, Sunam; Gallagher-Jones, Marcus; Kim, Yoonhee; Song, Changyong; Yao, Shengkun; Zhang, Jian; Zhang, Jianhua; Duan, Xiulan; Tono, Kensuke; Yabashi, Makina; Ishikawa, Tetsuya; Fan, Chunhai; Zhao, Yuliang; Chai, Zhifang; Gao, Xueyun; Earnest, Thomas; Jiang, Huaidong

    2016-09-01

    High-resolution imaging offers one of the most promising approaches for exploring and understanding the structure and function of biomaterials and biological systems. X-ray free-electron lasers (XFELs) combined with coherent diffraction imaging can theoretically provide high-resolution spatial information regarding biological materials using a single XFEL pulse. Currently, the application of this method suffers from the low scattering cross-section of biomaterials and X-ray damage to the sample. However, XFELs can provide pulses of such short duration that the data can be collected using the “diffract and destroy” approach before the effects of radiation damage on the data become significant. These experiments combine the use of enhanced coherent diffraction imaging with single-shot XFEL radiation to investigate the cellular architecture of Staphylococcus aureus with and without labeling by gold (Au) nanoclusters. The resolution of the images reconstructed from these diffraction patterns were twice as high or more for gold-labeled samples, demonstrating that this enhancement method provides a promising approach for the high-resolution imaging of biomaterials and biological systems.

  7. Single-pulse enhanced coherent diffraction imaging of bacteria with an X-ray free-electron laser

    Science.gov (United States)

    Fan, Jiadong; Sun, Zhibin; Wang, Yaling; Park, Jaehyun; Kim, Sunam; Gallagher-Jones, Marcus; Kim, Yoonhee; Song, Changyong; Yao, Shengkun; Zhang, Jian; Zhang, Jianhua; Duan, Xiulan; Tono, Kensuke; Yabashi, Makina; Ishikawa, Tetsuya; Fan, Chunhai; Zhao, Yuliang; Chai, Zhifang; Gao, Xueyun; Earnest, Thomas; Jiang, Huaidong

    2016-01-01

    High-resolution imaging offers one of the most promising approaches for exploring and understanding the structure and function of biomaterials and biological systems. X-ray free-electron lasers (XFELs) combined with coherent diffraction imaging can theoretically provide high-resolution spatial information regarding biological materials using a single XFEL pulse. Currently, the application of this method suffers from the low scattering cross-section of biomaterials and X-ray damage to the sample. However, XFELs can provide pulses of such short duration that the data can be collected using the “diffract and destroy” approach before the effects of radiation damage on the data become significant. These experiments combine the use of enhanced coherent diffraction imaging with single-shot XFEL radiation to investigate the cellular architecture of Staphylococcus aureus with and without labeling by gold (Au) nanoclusters. The resolution of the images reconstructed from these diffraction patterns were twice as high or more for gold-labeled samples, demonstrating that this enhancement method provides a promising approach for the high-resolution imaging of biomaterials and biological systems. PMID:27659203

  8. Anatomic vs. acquired image frame discordance in spectral domain optical coherence tomography minimum rim measurements.

    Directory of Open Access Journals (Sweden)

    Lin He

    Full Text Available PURPOSE: To quantify the effects of using the fovea to Bruch's membrane opening (FoBMO axis as the nasal-temporal midline for 30° sectoral (clock-hour spectral domain optical coherence tomography (SDOCT optic nerve head (ONH minimum rim width (MRW and area (MRA calculations. METHODS: The internal limiting membrane and BMO were delineated within 24 radial ONH B-scans in 222 eyes of 222 participants with ocular hypertension and glaucoma. For each eye the fovea was marked within the infrared reflectance image, the FoBMO angle (θ relative to the acquired image frame (AIF horizontal was calculated, the ONH was divided into 30° sectors using a FoBMO or AIF nasal/temporal axis, and SDOCT MRW and MRA were quantified within each FoBMO vs. AIF sector. For each sector, focal rim loss was calculated as the MRW and MRA gradients (i.e. the difference between the value for that sector and the one clockwise to it divided by 30°. Sectoral FoBMO vs. AIF discordance was calculated as the difference between the FoBMO and AIF values for each sector. Generalized estimating equations were used to predict the eyes and sectors of maximum FoBMO vs. AIF discordance. RESULTS: The mean FoBMO angle was -6.6±4.2° (range: -17° to +7°. FoBMO vs. AIF discordance in sectoral mean MRW and MRA was significant for 7 of 12 and 6 of 12 sectors, respectively (p<0.05, Wilcoxon test, Bonferroni correction. Eye-specific, FoBMO vs. AIF sectoral discordance was predicted by sectoral rim gradient (p<0.001 and FoBMO angle (p<0.001 and achieved maximum values of 83% for MRW and 101% for MRA. CONCLUSIONS: Using the FoBMO axis as the nasal-temporal axis to regionalize the ONH rather than a line parallel to the AIF horizontal axis significantly influences clock-hour SDOCT rim values. This effect is greatest in eyes with large FoBMO angles and sectors with focal rim loss.

  9. Longitudinal in vivo coherent anti-Stokes Raman scattering imaging of demyelination and remyelination in injured spinal cord

    Science.gov (United States)

    Shi, Yunzhou; Zhang, Delong; Huff, Terry B.; Wang, Xiaofei; Shi, Riyi; Xu, Xiao-Ming; Cheng, Ji-Xin

    2011-10-01

    In vivo imaging of white matter is important for the mechanistic understanding of demyelination and evaluation of remyelination therapies. Although white matter can be visualized by a strong coherent anti-Stokes Raman scattering (CARS) signal from axonal myelin, in vivo repetitive CARS imaging of the spinal cord remains a challenge due to complexities induced by the laminectomy surgery. We present a careful experimental design that enabled longitudinal CARS imaging of de- and remyelination at single axon level in live rats. In vivo CARS imaging of secretory phospholipase A2 induced myelin vesiculation, macrophage uptake of myelin debris, and spontaneous remyelination by Schwann cells are sequentially monitored over a 3 week period. Longitudinal visualization of de- and remyelination at a single axon level provides a novel platform for rational design of therapies aimed at promoting myelin plasticity and repair.

  10. Retinal optical coherence tomography image enhancement via shrinkage denoising using double-density dual-tree complex wavelet transform.

    Science.gov (United States)

    Chitchian, Shahab; Mayer, Markus A; Boretsky, Adam R; van Kuijk, Frederik J; Motamedi, Massoud

    2012-11-01

    ABSTRACT. Image enhancement of retinal structures, in optical coherence tomography (OCT) scans through denoising, has the potential to aid in the diagnosis of several eye diseases. In this paper, a locally adaptive denoising algorithm using double-density dual-tree complex wavelet transform, a combination of the double-density wavelet transform and the dual-tree complex wavelet transform, is applied to reduce speckle noise in OCT images of the retina. The algorithm overcomes the limitations of commonly used multiple frame averaging technique, namely the limited number of frames that can be recorded due to eye movements, by providing a comparable image quality in significantly less acquisition time equal to an order of magnitude less time compared to the averaging method. In addition, improvements of image quality metrics and 5 dB increase in the signal-to-noise ratio are attained.

  11. Optical coherence tomography imaging for evaluating the photo biomodulation effects on tissue regeneration in the oral cavity

    Science.gov (United States)

    Gimbel, Craig B.

    2008-03-01

    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.

  12. Reconstruction 3-dimensional image from 2-dimensional image of status optical coherence tomography (OCT) for analysis of changes in retinal thickness

    Energy Technology Data Exchange (ETDEWEB)

    Arinilhaq,; Widita, Rena [Department of Physics, Nuclear Physics and Biophysics Research Group, Institut Teknologi Bandung (Indonesia)

    2014-09-30

    Optical Coherence Tomography is often used in medical image acquisition to diagnose that change due easy to use and low price. Unfortunately, this type of examination produces a two-dimensional retinal image of the point of acquisition. Therefore, this study developed a method that combines and reconstruct 2-dimensional retinal images into three-dimensional images to display volumetric macular accurately. The system is built with three main stages: data acquisition, data extraction and 3-dimensional reconstruction. At data acquisition step, Optical Coherence Tomography produced six *.jpg images of each patient were further extracted with MATLAB 2010a software into six one-dimensional arrays. The six arrays are combined into a 3-dimensional matrix using a kriging interpolation method with SURFER9 resulting 3-dimensional graphics of macula. Finally, system provides three-dimensional color graphs based on the data distribution normal macula. The reconstruction system which has been designed produces three-dimensional images with size of 481 × 481 × h (retinal thickness) pixels.

  13. Time-resolved imaging with OKE-based time-gate: enhancement in spatial resolution using low-coherence ultra-short illumination

    CERN Document Server

    Purwar, Harsh; Rozé, Claude; Blaisot, Jean-Bernard

    2015-01-01

    We propose a collinear optical Kerr effect (OKE) based time-gate configuration with low coherence illumination source, derived from the supercontinuum (SC) generated by focusing the femtosecond laser pulses inside water. At first the spectral broadening in SC generation and corresponding changes in its coherence properties are studied and then a narrow band of wavelengths is extracted to use as the probe beam in the OKE-based time-gate configuration. The gate timings and spatial resolution of the time-gated images are also investigated. The low coherence of the probe ensures that the artifacts due to speckles from the laser are reduced to a minimum. To illustrate this a comparison of the time-resolved images of the fuel sprays obtained with this configuration has been made with the images obtained with the collinear, dual color configuration of the optical gate with coherent illumination.

  14. A joint estimation detection of Glaucoma progression in 3D spectral domain optical coherence tomography optic nerve head images.

    Science.gov (United States)

    Belghith, Akram; Bowd, Christopher; Weinreb, Robert N; Zangwill, Linda M

    2014-03-18

    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.

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

    Science.gov (United States)

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

    2010-02-01

    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.

  16. A joint estimation detection of Glaucoma progression in 3D spectral domain optical coherence tomography optic nerve head images

    Science.gov (United States)

    Belghith, Akram; Bowd, Christopher; Weinreb, Robert N.; Zangwill, Linda M.

    2014-03-01

    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. Ultrahigh phase-stable swept-source optical coherence tomography as a cardiac imaging platform (Conference Presentation)

    Science.gov (United States)

    Ling, Yuye; Hendon, Christine P.

    2016-02-01

    Functional extensions to optical coherence tomography (OCT) provide useful imaging contrasts that are complementary to conventional OCT. Our goal is to characterize tissue types within the myocardial due to remodeling and therapy. High-speed imaging is necessary to extract mechanical properties and dynamics of fiber orientation changes in a beating heart. Functional extensions of OCT such as polarization sensitive and optical coherence elastography (OCE) require high phase stability of the system, which is a drawback of current mechanically tuned swept source OCT systems. Here we present a high-speed functional imaging platform, which includes an ultrahigh-phase-stable swept source equipped with KTN deflector from NTT-AT. The swept source does not require mechanical movements during the wavelength sweeping; it is electrically tuned. The inter-sweep phase variance of the system was measured to be less than 300 ps at a path length difference of ~2 mm. The axial resolution of the system is 20 µm and the -10 dB fall-off depth is about 3.2 mm. The sample arm has an 8 mmx8 mm field of view with a lateral resolution of approximately 18 µm. The sample arm uses a two-axis MEMS mirror, which is programmable and capable of scanning arbitrary patterns at a sampling rate of 50 kHz. Preliminary imaging results showed differences in polarization properties and image penetration in ablated and normal myocardium. In the future, we will conduct dynamic stretching experiments with strips of human myocardial tissue to characterize mechanical properties using OCE. With high speed imaging of 200 kHz and an all-fiber design, we will work towards catheter-based functional imaging.

  18. Spatiotemporal correlation of optical coherence tomography in-vivo images of rabbit airway for the diagnosis of edema

    Science.gov (United States)

    Kang, DongYel; Wang, Alex; Volgger, Veronika; Chen, Zhongping; Wong, Brian J. F.

    2015-07-01

    Detection of an early stage of subglottic edema is vital for airway management and prevention of stenosis, a life-threatening condition in critically ill neonates. As an observer for the task of diagnosing edema in vivo, we investigated spatiotemporal correlation (STC) of full-range optical coherence tomography (OCT) images acquired in the rabbit airway with experimentally simulated edema. Operating the STC observer on OCT images generates STC coefficients as test statistics for the statistical decision task. Resulting from this, the receiver operating characteristic (ROC) curves for the diagnosis of airway edema with full-range OCT in-vivo images were extracted and areas under ROC curves were calculated. These statistically quantified results demonstrated the potential clinical feasibility of the STC method as a means to identify early airway edema.

  19. A high-efficiency fiber-based imaging system for co-registered autofluorescence and optical coherence tomography.

    Science.gov (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

    2014-09-01

    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.

  20. Ultra-high performance mirror systems for the imaging and coherence beamline I13 at the Diamond Light Source

    Science.gov (United States)

    Wagner, U. H.; Alcock, S.; Ludbrook, G.; Wiatryzk, J.; Rau, C.

    2012-05-01

    I13L is a 250m long hard x-ray beamline (6 keV to 35 keV) currently under construction at the Diamond Light Source. The beamline comprises of two independent experimental endstations: one for imaging in direct space using x-ray microscopy and one for imaging in reciprocal space using coherent diffraction based imaging techniques. To minimise the impact of thermal fluctuations and vibrations onto the beamline performance, we are developing a new generation of ultra-stable beamline instrumentation with highly repeatable adjustment mechanisms using low thermal expansion materials like granite and large piezo-driven flexure stages. For minimising the beam distortion we use very high quality optical components like large ion-beam polished mirrors. In this paper we present the first metrology results on a newly designed mirror system following this design philosophy.

  1. High-dynamic-range microscope imaging based on exposure bracketing in full-field optical coherence tomography.

    Science.gov (United States)

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

    2016-04-01

    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.

  2. Temporal correlation of optical coherence tomography in-vivo images of rabbit airway for the diagnosis of edema

    Science.gov (United States)

    Kang, DongYel; Wang, Alex; Tjoa, Tjoson; Volgger, Veronika; Hamamoto, Ashley; Su, Erica; Jing, Joseph; Chen, Zhongping; Wong, Brian J. F.

    2014-03-01

    Recently, full-range optical coherence tomography (OCT) systems have been developed to image the human airway. These novel systems utilize a fiber-based OCT probe which acquires three-dimensional (3-D) images with micrometer resolution. Following an airway injury, mucosal edema is the first step in the body's inflammatory response, which occasionally leads to airway stenosis, a life-threatening condition for critically ill newborns. Therefore, early detection of edema is vital for airway management and prevention of stenosis. In order to examine the potential of the full-range OCT to diagnose edema, we investigated temporal correlation of OCT images obtained from the subglottic airway of live rabbits. Temporally correlated OCT images were acquired at fixed locations in the rabbit subglottis of either artificially induced edema or normal tissues. Edematous tissue was experimentally modeled by injecting saline beneath the epithelial layer of the subglottic mucosa. The calculated cross temporal correlations between OCT images of normal airway regions show periodicity that correlates with the respiratory motion of the airway. However, the temporal correlation functions calculated from OCT images of the edematous regions show randomness without the periodic characteristic. These in-vivo experimental results of temporal correlations between OCT images show the potential of a computer-based or -aided diagnosis of edema in the human respiratory mucosa with a full-range OCT system.

  3. Label-free imaging of intracellular motility by low-coherent quantitative phase microscope in reflection geometry

    Science.gov (United States)

    Yamauchi, Toyohiko; Iwai, Hidenao; Yamashita, Yutaka

    2011-11-01

    We demonstrate tomographic imaging of intracellular activity of living cells by a low-coherent quantitative phase microscope. The intracellular organelles, such as the nucleus, nucleolus, and mitochondria, are moving around inside living cells, driven by the cellular physiological activity. In order to visualize the intracellular motility in a label-free manner we have developed a reflection-type quantitative phase microscope which employs the phase shifting interferometric technique with a low-coherent light source. The phase shifting interferometry enables us to quantitatively measure the intensity and phase of the optical field, and the low-coherence interferometry makes it possible to selectively probe a specific sectioning plane in the cell volume. The results quantitatively revealed the depth-resolved fluctuations of intracellular surfaces so that the plasma membrane and the membranes of intracellular organelles were independently measured. The transversal and the vertical spatial resolutions were 0.56 μm and 0.93 μm, respectively, and the mechanical sensitivity of the phase measurement was 1.2 nanometers. The mean-squared displacement was applied as a statistical tool to analyze the temporal fluctuation of the intracellular organelles. To the best of our knowledge, our system visualized depth-resolved intracellular organelles motion for the first time in sub-micrometer resolution without contrast agents.

  4. Enhanced Visualization of Subtle Outer Retinal Pathology by En Face Optical Coherence Tomography and Correlation with Multi-Modal Imaging

    Science.gov (United States)

    Chew, Avenell L.; Lamey, Tina; McLaren, Terri; De Roach, John

    2016-01-01

    Purpose To present en face optical coherence tomography (OCT) images generated by graph-search theory algorithm-based custom software and examine correlation with other imaging modalities. Methods En face OCT images derived from high density OCT volumetric scans of 3 healthy subjects and 4 patients using a custom algorithm (graph-search theory) and commercial software (Heidelberg Eye Explorer software (Heidelberg Engineering)) were compared and correlated with near infrared reflectance, fundus autofluorescence, adaptive optics flood-illumination ophthalmoscopy (AO-FIO) and microperimetry. Results Commercial software was unable to generate accurate en face OCT images in eyes with retinal pigment epithelium (RPE) pathology due to segmentation error at the level of Bruch’s membrane (BM). Accurate segmentation of the basal RPE and BM was achieved using custom software. The en face OCT images from eyes with isolated interdigitation or ellipsoid zone pathology were of similar quality between custom software and Heidelberg Eye Explorer software in the absence of any other significant outer retinal pathology. En face OCT images demonstrated angioid streaks, lesions of acute macular neuroretinopathy, hydroxychloroquine toxicity and Bietti crystalline deposits that correlated with other imaging modalities. Conclusions Graph-search theory algorithm helps to overcome the limitations of outer retinal segmentation inaccuracies in commercial software. En face OCT images can provide detailed topography of the reflectivity within a specific layer of the retina which correlates with other forms of fundus imaging. Our results highlight the need for standardization of image reflectivity to facilitate quantification of en face OCT images and longitudinal analysis. PMID:27959968

  5. High Dynamic Range Imaging Concept-Based Signal Enhancement Method Reduced the Optical Coherence Tomography Measurement Variability

    Science.gov (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.

    2013-01-01

    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

  6. A pilot study on slit lamp-adapted optical coherence tomography imaging of trabeculectomy filtering blebs.

    NARCIS (Netherlands)

    Theelen, T.; Wesseling, P.; Keunen, J.E.E.; Klevering, B.J.

    2007-01-01

    BACKGROUND: Our study aims to identify anatomical characteristics of glaucoma filtering blebs by means of slit lamp-adapted optical coherence tomography (SL-OCT) and to identify new parameters for the functional prognosis of the filter in the early post-operative period. METHODS: Patients with

  7. Coherent anti-Stokes Raman scattering (CARS) microscopy driving the future of loaded mesoporous silica imaging

    NARCIS (Netherlands)

    Fussell, A.L.; Mah, Pei Ting; Offerhaus, Herman L.; Niemi, Sanna-Mari; Salonen, Jarno; Santos, Helder A.; Strachan, Clare

    2014-01-01

    This study reports the use of variants of coherent anti-Stokes Raman scattering (CARS) microscopy as a novel method for improved physicochemical characterization of drug-loaded silica particles. Ordered mesoporous silica is a biomaterial that can be loaded to carry a number of biochemicals,

  8. 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.

    2015-01-01

    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

  9. Performance evaluation of an all-fiber image-reject homodyne coherent Doppler wind lidar

    DEFF Research Database (Denmark)

    Abari, Cyrus F.; Pedersen, Anders Tegtmeier; Dellwik, Ebba

    2015-01-01

    The main purpose of this study is to evaluate the near-zero wind velocity measurement performance of two separate 1.5 µm all-fiber coherent Doppler lidars (CDLs). The performance characterization is carried out through the presentation of the results from two separate atmospheric field campaigns...

  10. 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.

    2015-01-01

    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

  11. 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.

    2015-01-01

    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

  12. Dynamic imaging of coherent sources reveals different network connectivity underlying the generation and perpetuation of epileptic seizures.

    Directory of Open Access Journals (Sweden)

    Lydia Elshoff

    Full Text Available The concept of focal epilepsies includes a seizure origin in brain regions with hyper synchronous activity (epileptogenic zone and seizure onset zone and a complex epileptic network of different brain areas involved in the generation, propagation, and modulation of seizures. The purpose of this work was to study functional and effective connectivity between regions involved in networks of epileptic seizures. The beginning and middle part of focal seizures from ictal surface EEG data were analyzed using dynamic imaging of coherent sources (DICS, an inverse solution in the frequency domain which describes neuronal networks and coherences of oscillatory brain activities. The information flow (effective connectivity between coherent sources was investigated using the renormalized partial directed coherence (RPDC method. In 8/11 patients, the first and second source of epileptic activity as found by DICS were concordant with the operative resection site; these patients became seizure free after epilepsy surgery. In the remaining 3 patients, the results of DICS / RPDC calculations and the resection site were discordant; these patients had a poorer post-operative outcome. The first sources as found by DICS were located predominantly in cortical structures; subsequent sources included some subcortical structures: thalamus, Nucl. Subthalamicus and cerebellum. DICS seems to be a powerful tool to define the seizure onset zone and the epileptic networks involved. Seizure generation seems to be related to the propagation of epileptic activity from the primary source in the seizure onset zone, and maintenance of seizures is attributed to the perpetuation of epileptic activity between nodes in the epileptic network. Despite of these promising results, this proof of principle study needs further confirmation prior to the use of the described methods in the clinical praxis.

  13. Application of optical coherence tomography (OCT) as a 3-dimensional imaging technique for roll-to-roll coated polymer solar cells

    DEFF Research Database (Denmark)

    Thrane, Lars; Jørgensen, Thomas Martini; Jørgensen, Mikkel

    2012-01-01

    The 3-dimensional imaging of complete polymer solar cells prepared by roll-to-roll coating was carried out using high-resolution 1322 nm optical coherence tomography (OCT) system. We found it possible to image the 3-dimensional structure of the entire solar cell that comprises UV-barrier, barrier...

  14. Comparative assessments of the effects of alcohol exposure on fetal brain development using optical coherence tomography and ultrasound imaging

    Science.gov (United States)

    Sudheendran, Narendran; Bake, Shameena; Miranda, Rajesh C.; Larin, Kirill V.

    2013-02-01

    The developing fetal brain is vulnerable to a variety of environmental agents including maternal ethanol consumption. Preclinical studies on the development and amelioration of fetal teratology would be significantly facilitated by the application of high resolution imaging technologies like optical coherence tomography (OCT) and high-frequency ultrasound (US). This study investigates the ability of these imaging technologies to measure the effects of maternal ethanol exposure on brain development, ex vivo, in fetal mice. Pregnant mice at gestational day 12.5 were administered ethanol (3 g/Kg b.wt.) or water by intragastric gavage, twice daily for three consecutive days. On gestational day 14.5, fetuses were collected and imaged. Three-dimensional images of the mice fetus brains were obtained by OCT and high-resolution US, and the volumes of the left and right ventricles of the brain were measured. Ethanol-exposed fetuses exhibited a statistically significant, 2-fold increase in average left and right ventricular volumes compared with the ventricular volume of control fetuses, with OCT-derived measures of 0.38 and 0.18 mm3, respectively, whereas the boundaries of the fetal mouse lateral ventricles were not clearly definable with US imaging. Our results indicate that OCT is a useful technology for assessing ventriculomegaly accompanying alcohol-induced developmental delay. This study clearly demonstrated advantages of using OCT for quantitative assessment of embryonic development compared with US imaging.

  15. Enhanced truncated-correlation photothermal coherence tomography with application to deep subsurface defect imaging and 3-dimensional reconstructions

    Science.gov (United States)

    Tavakolian, Pantea; Sivagurunathan, Koneswaran; Mandelis, Andreas

    2017-07-01

    Photothermal diffusion-wave imaging is a promising technique for non-destructive evaluation and medical applications. Several diffusion-wave techniques have been developed to produce depth-resolved planar images of solids and to overcome imaging depth and image blurring limitations imposed by the physics of parabolic diffusion waves. Truncated-Correlation Photothermal Coherence Tomography (TC-PCT) is the most successful class of these methodologies to-date providing 3-D subsurface visualization with maximum depth penetration and high axial and lateral resolution. To extend the depth range and axial and lateral resolution, an in-depth analysis of TC-PCT, a novel imaging system with improved instrumentation, and an optimized reconstruction algorithm over the original TC-PCT technique is developed. Thermal waves produced by a laser chirped pulsed heat source in a finite thickness solid and the image reconstruction algorithm are investigated from the theoretical point of view. 3-D visualization of subsurface defects utilizing the new TC-PCT system is reported. The results demonstrate that this method is able to detect subsurface defects at the depth range of ˜4 mm in a steel sample, which exhibits dynamic range improvement by a factor of 2.6 compared to the original TC-PCT. This depth does not represent the upper limit of the enhanced TC-PCT. Lateral resolution in the steel sample was measured to be ˜31 μm.

  16. Intraoperative handheld probe for 3D imaging of pediatric benign vocal fold lesions using optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Benboujja, Fouzi; Garcia, Jordan; Beaudette, Kathy; Strupler, Mathias; Hartnick, Christopher J.; Boudoux, Caroline

    2016-02-01

    Excessive and repetitive force applied on vocal fold tissue can induce benign vocal fold lesions. Children affected suffer from chronic hoarseness. In this instance, the vibratory ability of the folds, a complex layered microanatomy, becomes impaired. Histological findings have shown that lesions produce a remodeling of sup-epithelial vocal fold layers. However, our understanding of lesion features and development is still limited. Indeed, conventional imaging techniques do not allow a non-invasive assessment of sub-epithelial integrity of the vocal fold. Furthermore, it remains challenging to differentiate these sub-epithelial lesions (such as bilateral nodules, polyps and cysts) from a clinical perspective, as their outer surfaces are relatively similar. As treatment strategy differs for each lesion type, it is critical to efficiently differentiate sub-epithelial alterations involved in benign lesions. In this study, we developed an optical coherence tomography (OCT) based handheld probe suitable for pediatric laryngological imaging. The probe allows for rapid three-dimensional imaging of vocal fold lesions. The system is adapted to allow for high-resolution intra-operative imaging. We imaged 20 patients undergoing direct laryngoscopy during which we looked at different benign pediatric pathologies such as bilateral nodules, cysts and laryngeal papillomatosis and compared them to healthy tissue. We qualitatively and quantitatively characterized laryngeal pathologies and demonstrated the added advantage of using 3D OCT imaging for lesion discrimination and margin assessment. OCT evaluation of the integrity of the vocal cord could yield to a better pediatric management of laryngeal diseases.

  17. Swept source optical coherence tomography for in vivo imaging and vibrometry in the apex of the mouse cochlea

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hee Yoon [E.L. Ginzton Laboratory and Department of Electrical Engineering, Stanford University, Stanford, California (United States); Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California (United States); Raphael, Patrick D.; Oghalai, John S. [Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California (United States); Ellerbee, Audrey K. [E.L. Ginzton Laboratory and Department of Electrical Engineering, Stanford University, Stanford, California (United States); Applegate, Brian E. [Department of Biomedical Engineering, Texas A& M University, College Station, Texas (United States)

    2015-12-31

    Cochlear amplification has been most commonly investigated by measuring the vibrations of the basilar membrane in animal models. Several different techniques have been used for measuring these vibrations such as laser Doppler vibrometry, miniature pressure sensors, low coherence interferometry, and spectral-domain optical coherence tomography (SD-OCT). We have built a swept-source OCT (SS-OCT) system, which is similar to SD-OCT in that it is capable of performing both imaging and vibration measurements within the mouse cochlea in vivo without having to open the bone. In vivo 3D images of a mouse cochlea were obtained, and the basilar membrane, tectorial membrane, Reissner’s membrane, tunnel of Corti, and reticular lamina could all be resolved. We measured vibrations of multiple structures within the mouse cochlea to sound stimuli. As well, we measured the radial deflections of the reticular lamina and tectorial membrane to estimate the displacement of the outer hair cell stereocilia. These measurements have the potential to more clearly define the mechanisms underlying the linear and non-linear processes within the mammalian cochlea.

  18. Macromolecular structures probed by combining single-shot free-electron laser diffraction with synchrotron coherent X-ray imaging.

    Science.gov (United States)

    Gallagher-Jones, Marcus; Bessho, Yoshitaka; Kim, Sunam; Park, Jaehyun; Kim, Sangsoo; Nam, Daewoong; Kim, Chan; Kim, Yoonhee; Noh, Do Young; Miyashita, Osamu; Tama, Florence; Joti, Yasumasa; Kameshima, Takashi; Hatsui, Takaki; Tono, Kensuke; Kohmura, Yoshiki; Yabashi, Makina; Hasnain, S Samar; Ishikawa, Tetsuya; Song, Changyong

    2014-05-02

    Nanostructures formed from biological macromolecular complexes utilizing the self-assembly properties of smaller building blocks such as DNA and RNA hold promise for many applications, including sensing and drug delivery. New tools are required for their structural characterization. Intense, femtosecond X-ray pulses from X-ray free-electron lasers enable single-shot imaging allowing for instantaneous views of nanostructures at ambient temperatures. When combined judiciously with synchrotron X-rays of a complimentary nature, suitable for observing steady-state features, it is possible to perform ab initio structural investigation. Here we demonstrate a successful combination of femtosecond X-ray single-shot diffraction with an X-ray free-electron laser and coherent diffraction imaging with synchrotron X-rays to provide an insight into the nanostructure formation of a biological macromolecular complex: RNA interference microsponges. This newly introduced multimodal analysis with coherent X-rays can be applied to unveil nano-scale structural motifs from functional nanomaterials or biological nanocomplexes, without requiring a priori knowledge.

  19. Imaging coherent transport in chemical vapor deposition graphene wide constriction by scanning gate microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, Chiashain; Matsunaga, Masahiro; Ochiai, Yuichi; Aoki, Nobuyuki, E-mail: n-aoki@faculty.chiba-u.jp, E-mail: ctliang@phys.ntu.edu.tw [Graduate School of Advanced Integration Science, Chiba University, Chiba 263-8522 (Japan); Liu, Fan-Hung [Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan (China); Woo, Tak-Pong [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Lin, Li-Hung [Department of Electrophysics, National Chiayi University, Chiayi 600, Taiwan (China); Oto, Kenichi [Graduate School of Science, Chiba University, Chiba 263-8522 (Japan); Liang, Chi-Te, E-mail: n-aoki@faculty.chiba-u.jp, E-mail: ctliang@phys.ntu.edu.tw [Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan (China); Department of Physics, National Taiwan University, Taipei 106, Taiwan (China)

    2016-03-21

    We use a scanning gate microscopy to perturb coherent transport in chemical vapor deposition (CVD) graphene wide constriction. Particularly, we observe conductance oscillations in the wide constriction region (W ∼ 800 nm) characterized by spatial conductance variations, which imply formation of the nanometer-scale ring structure due to the merged domains and intrinsic grain boundaries. Moreover, additional hot charges from high current can suppress the coherent transport, suggesting that the hot carriers with a wide spreading kinetic energy could easily tunnel merged domains and intrinsic grain boundaries in CVD-grown graphene due to the heating effect, a great advantage for applications in graphene-based interference-type nano-electronics.

  20. Three-dimensional coherent x-ray diffraction imaging of molten iron in mantle olivine at nanoscale resolution.

    Science.gov (United States)

    Jiang, Huaidong; Xu, Rui; Chen, Chien-Chun; Yang, Wenge; Fan, Jiadong; Tao, Xutang; Song, Changyong; Kohmura, Yoshiki; Xiao, Tiqiao; Wang, Yong; Fei, Yingwei; Ishikawa, Tetsuya; Mao, Wendy L; Miao, Jianwei

    2013-05-17

    We report quantitative 3D coherent x-ray diffraction imaging of a molten Fe-rich alloy and crystalline olivine sample, synthesized at 6 GPa and 1800 °C, with nanoscale resolution. The 3D mass density map is determined and the 3D distribution of the Fe-rich and Fe-S phases in the olivine-Fe-S sample is observed. Our results indicate that the Fe-rich melt exhibits varied 3D shapes and sizes in the olivine matrix. This work has potential for not only improving our understanding of the complex interactions between Fe-rich core-forming melts and mantle silicate phases but also paves the way for quantitative 3D imaging of materials at nanoscale resolution under extreme pressures and temperatures.

  1. In situ study of annealing-induced strain relaxation in diamond nanoparticles using Bragg coherent diffraction imaging

    Directory of Open Access Journals (Sweden)

    S. O. Hruszkewycz

    2017-02-01

    Full Text Available We observed changes in morphology and internal strain state of commercial diamond nanocrystals during high-temperature annealing. Three nanodiamonds were measured with Bragg coherent x-ray diffraction imaging, yielding three-dimensional strain-sensitive images as a function of time/temperature. Up to temperatures of 800 °C, crystals with Gaussian strain distributions with a full-width-at-half-maximum of less than 8×10−4 were largely unchanged, and annealing-induced strain relaxation was observed in a nanodiamond with maximum lattice distortions above this threshold. X-ray measurements found changes in nanodiamond morphology at temperatures above 600 °C that are consistent with graphitization of the surface, a result verified with ensemble Raman measurements.

  2. Application of color image processing and low-coherent optical computer tomography in evaluation of adhesive interfaces of dental restorations

    Science.gov (United States)

    Bessudnova, Nadezda O.; Shlyapnikova, Olga A.; Venig, Sergey B.; Genina, Elina A.; Sadovnikov, Alexandr V.

    2015-03-01

    Durability of bonded interfaces between dentin and a polymer material in resin-based composite restorations remains a clinical dentistry challenge. In the present study the evolution of bonded interfaces in biological active environment is estimated in vivo. A novel in vivo method of visual diagnostics that involves digital processing of color images of composite restorations and allows the evaluation of adhesive interface quality over time, has been developed and tested on a group of volunteers. However, the application of the method is limited to the analysis of superficial adhesive interfaces. Low-coherent optical computer tomography (OCT) has been tested as a powerful non-invasive tool for in vivo, in situ clinical diagnostics of adhesive interfaces over time. In the long-term perspective adhesive interface monitoring using standard methods of clinical diagnostics along with colour image analysis and OCT could make it possible to objectivise and prognosticate the clinical longevity of composite resin-based restorations with adhesive interfaces.

  3. Optical design of an optical coherence tomography and multispectral fluorescence imaging endoscope to detect early stage ovarian cancer

    Science.gov (United States)

    Tate, Tyler; Keenan, Molly; Swan, Elizabeth; Black, John; Utzinger, Urs; Barton, Jennifer

    2014-12-01

    The five year survival rate for ovarian cancer is over 90% if early detection occurs, yet no effective early screening method exists. We have designed and are constructing a dual modality Optical Coherence Tomography (OCT) and Multispectral Fluorescence Imaging (MFI) endoscope to optically screen the Fallopian tube and ovary for early stage cancer. The endoscope reaches the ovary via the natural pathway of the vagina, cervix, uterus and Fallopian tube. In order to navigate the Fallopian tube the endoscope must have an outer diameter of 600 μm, be highly flexible, steerable, tracking and nonperforating. The imaging systems consists of six optical subsystems, two from OCT and four from MFI. The optical subsystems have independent and interrelated design criteria. The endoscope will be tested on realistic tissue models and ex vivo tissue to prove feasibility of future human trials. Ultimately the project aims to provide women the first effective ovarian cancer screening technique.

  4. Extraction of optical scattering parameters and attenuation compensation in optical coherence tomography images of multi-layered tissue structures

    DEFF Research Database (Denmark)

    Thrane, Lars; Frosz, Michael Henoch; Tycho, Andreas

    2004-01-01

    A recently developed analytical optical coherence tomography (OCT) model [Thrane et al., J. Opt. Soc. Am. A 17, 484 (2000)] allows the extraction of optical scattering parameters from OCT images, thereby permitting attenuation compensation in those images. By expanding this theoretical model, we...... have developed a new method for extracting optical scattering parameters from multilayered tissue structures in vivo. To verify this, we used a Monte Carlo (MC) OCT model as a numerical phantom to simulate the OCT signal for het-erogeneous multilayered tissue. Excellent agreement between the extracted...... values of the optical scattering properties of the different layers and the corresponding input reference values of the MC simulation was obtained, which demonstrates the feasibility of the method for in vivo applications. This is to our knowledge the first time such verification has been obtained...

  5. Images of small-scale mantle heterogeneity obtained from coherence functions of phase and log amplitude fluctuations

    Science.gov (United States)

    Tian, Y.; Cormier, V. F.

    2015-12-01

    Traditional deterministic tomography cannot reveal the characteristics of small-scale (smaller than 100 km) heterogeneities in deep earth. Stochastic tomography, which inverts joint angular-transverse coherence functions (JATCF), can be used to image the statistics of small-scale heterogeneity. We test the resolution of this method using a pseudo-spectal method to synthesize the seismic wavefield in a reference radial symmetric Earth model perturbed by statistically described heterogeneity. JACTFs are calculated from the fluctuation of phase and log amplitude of transmitted waves in the heterogeneous model differenced from those predicted in the reference model. Example images are obtained from processing JACTFs measured from teleseismic data observed by Earthscope's USArray. Depth and lateral variations of the statistics of heterogeneity scales constrain the nature of chemical heterogeneity and mantle circulation

  6. Quantitative evaluation of scattering in optical coherence tomography skin images using the extended Huygens-Fresnel theorem.

    Science.gov (United States)

    Avanaki, Mohammad R N; Podoleanu, Adrian Gh; Schofield, John B; Jones, Carole; Sira, Manu; Liu, Yan; Hojjat, Ali

    2013-03-10

    An optical properties extraction algorithm is developed based on enhanced Huygens-Fresnel light propagation theorem, to extract the scattering coefficient of a specific region in an optical coherence tomography (OCT) image. The aim is to quantitatively analyze the OCT images. The algorithm is evaluated using a set of phantoms with different concentrations of scatterers, designed based on Mie theory. The algorithm is then used to analyze basal cell carcinoma and healthy eyelid tissues, demonstrating distinguishable differences in the scattering coefficient between these tissues. In this study, we have taken advantage of the simplification introduced by the utilization of a dynamic focus OCT system. This eliminates the need to deconvolve the reflectivity profile with the confocal gate profile, as the sensitivity of the OCT system is constant throughout the axial range.

  7. Long-wavelength optical coherence tomography at 1.7 µm for enhanced imaging depth

    OpenAIRE

    Sharma, Utkarsh; Chang, Ernest W.; Seok H Yun

    2008-01-01

    Multiple scattering in a sample presents a significant limitation to achieve meaningful structural information at deeper penetration depths in optical coherence tomography (OCT). Previous studies suggest that the spectral region around 1.7 µm may exhibit reduced scattering coefficients in biological tissues compared to the widely used wavelengths around 1.3 µm. To investigate this long-wavelength region, we developed a wavelength-swept laser at 1.7 µm wavelength and conducted OCT or optical f...

  8. Multi-Modal Imaging Including Optical Coherence Tomography Angiography in Patients With Posterior Multifocal Placoid Pigment Epitheliopathy.

    Science.gov (United States)

    Werner, Jens Ulrich; Enders, Christian; Lang, Gerhard Klaus; Lang, Gabriele Elisabeth

    2017-09-01

    New imaging methods provide novel insights into the pathogenesis of acute posterior multifocal placoid pigment epitheliopathy (APMPPE). Four patients (eight eyes) in acute, subacute, and late phases of the disease were analyzed with multi-modal imaging methods including optical coherence tomography angiography (OCTA), structural OCT, fundus photography, and fundus autofluorescence. One patient was observed during the entire disease course. In acute and subacute phases of the disease, an early blockage in fluorescein angiography was found. OCTA showed perfusion defects in choriocapillaris and choroid slabs. During the course of disease, perfusion deficits observed in OCTA imaging resolved first in the choroid and then in the choriocapillaris slab. Multi-modal imaging including OCTA supports the thesis that the underlying pathology of APMPPE is an inflammatory impairment of the choroidal circulation with secondary damage to the outer retina. OCTA might be able to replace fluorescein and indocyanine angiography in the diagnostic work-up of APMPPE. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:727-733.]. Copyright 2017, SLACK Incorporated.

  9. In-vivo gingival sulcus imaging using full-range, complex-conjugate-free, endoscopic spectral domain optical coherence tomography

    Science.gov (United States)

    Huang, Yong; Zhang, Kang; Yi, WonJin; Kang, Jin U.

    2012-01-01

    Frequent monitoring of gingival sulcus will provide valuable information for judging the presence and severity of periodontal disease. Optical coherence tomography, as a 3D high resolution high speed imaging modality is able to provide information for pocket depth, gum contour, gum texture, gum recession simultaneously. A handheld forward-viewing miniature resonant fiber-scanning probe was developed for in-vivo gingival sulcus imaging. The fiber cantilever driven by magnetic force vibrates at resonant frequency. A synchronized linear phase-modulation was applied in the reference arm by the galvanometer-driven reference mirror. Full-range, complex-conjugate-free, real-time endoscopic SD-OCT was achieved by accelerating the data process using graphics processing unit. Preliminary results showed a real-time in-vivo imaging at 33 fps with an imaging range of lateral 2 mm by depth 3 mm. Gap between the tooth and gum area was clearly visualized. Further quantification analysis of the gingival sulcus will be performed on the image acquired.

  10. Optical coherence tomography based imaging of dental demineralisation and cavity restoration in 840 nm and 1310 nm wavelength regions

    Science.gov (United States)

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

    2016-08-01

    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.

  11. Keyhole reflection-mode coherent diffraction imaging of nano-patterned surfaces using a tabletop EUV source

    Science.gov (United States)

    Shanblatt, Elisabeth; Seaberg, Matthew; Zhang, Bosheng; Gardner, Dennis; Murnane, Margaret; Kapyetn, Henry; Adams, Daniel

    2014-03-01

    We demonstrate the first reflection-mode keyhole coherent diffraction imaging (CDI) of non-isolated samples from a single diffraction pattern. A tabletop high harmonic generation (HHG) beam at 30 nm with a curved wave-front is used to illuminate Ti nano-patterns on a Si substrate at 45 degree angle of incidence. The 30 nm illumination beam profile is first characterized using ptychograhic CDI. Keyhole CDI is then used to image the nano-sample. In contrast to ptychography CDI, keyhole CDI needs only one diffraction pattern, and therefore requires no scanning of the sample. This is a significant advantage for ultrafast pump-probe imaging of thermal or spin transport, allowing a sequence of time-delayed images of the same region to be easily acquired. Our technique opens the door for imaging dynamics in nanostructures with sub-10 nm spatial resolution and fs temporal resolution. National Science Foundation Engineering Research Center in EUV Science and Technology, AMRDEC, DARPA PULSE, SRC grant 2013-OJ-2443, NSSEFF Fellowship, NSF IGERT program.

  12. Electroencephalograpic coherence

    Directory of Open Access Journals (Sweden)

    Simon Brežan

    2004-08-01

    Full Text Available Different brain areas process various aspects of information in parallel as well as segregated way. It is not known, how is this information integrated into a unitary percept or action. The binding problem is one of the key problems in understanding brain function. Synchronized oscillatory activity of neurons is one possible mechanism of the functional integration of different communicating brain areas. The binding has been well-studied in the visual system, but it could also serve as a mechanism in visuomotor integration or functional coupling present with other brain processes and behavioural modes (perception, complex motor behaviour, selective attention, learning, working memory, etc.. Interregional synchronization of the electroencephalographic (EEG signal can be determined by EEG coherence analysis. In the article we present a research example of coherence changes in a visuomotor task. During this task, coherence between visual and motor brain areas increased. This might reflect functional coupling between those areas, but it could also be influenced by other cognitive processes (e.g. selective attention. Coherence analysis is suitable for studying integrative brain function. Because it measures only one of the possible mechanisms of integration, it offers promise especially when combined with other electrophysiological and functional imaging methods.

  13. A plane wave analysis of coherent holographic image reconstruction by phase transfer

    CERN Document Server

    Field, Jeffrey J; Bartels, Randy A

    2015-01-01

    Fluorescent imaging plays a critical role in a myriad of scientific endeavors, particularly in the biological sciences. Three-dimensional imaging of fluorescent intensity often requires serial data acquisition, that is voxel-by-voxel collection of fluorescent light emitted throughout the specimen with a non-imaging single-element detector. While non-imaging fluorescence detection offers some measure of scattering robustness, the rate at which dynamic specimens can be imaged is severely limited. Other fluorescent imaging techniques utilize imaging detection to enhance collection rates. A notable example is light-sheet fluorescence microscopy, also known as selective-plane illumination microscopy (SPIM), which illuminates a large region within the specimen and collects emitted fluorescent light at an angle either perpendicular or oblique to the illumination light sheet. Unfortunately, scattering of the emitted fluorescent light can cause blurring of the collected images in highly turbid biological media. We rec...

  14. Which histological characteristics of basal cell carcinomas influence the quality of optical coherence tomography imaging?

    DEFF Research Database (Denmark)

    Mogensen, M.; Thrane, Lars; Jørgensen, Thomas Martini;

    2009-01-01

    We explore how histopathology parameters influence OCT imaging of basal cell carcinomas (BCC) and address whether such parameters correlate with the quality of the recorded OCT images. Our results indicate that inflammation impairs OCT imaging and that sun-damaged skin can sometimes provide more...

  15. The choroid and lamina cribrosa is affected in patients with Parkinson's disease: enhanced depth imaging optical coherence tomography study.

    Science.gov (United States)

    Eraslan, Muhsin; Cerman, Eren; Yildiz Balci, Sevcan; Celiker, Hande; Sahin, Ozlem; Temel, Ahmet; Suer, Devran; Tuncer Elmaci, Nese

    2016-02-01

    To compare lamina cribrosa (LC) and choroidal thicknesses using enhanced depth imaging optical coherence tomography (EDI-OCT) in patients with Parkinson's disease (PD) and healthy controls. A total number of 44 eyes of 22 patients with PD and 50 eyes of 25 healthy subjects were utilized in this institutional cross-sectional study. After a complete ophthalmic examination, all eyes were imaged with OCT (RTVue-100 version 5.1 Fourier-domain optical coherence tomography; Optovue Inc., Fremont, CA, USA); LC and choroidal thickness were assessed. The mean LC thicknesses were 209.4 ± 40.2 μm in patients with PD and 292.5 ± 33.7 μm in control subjects. There was a significant difference in the mean LC thickness between the groups (p choroidal thickness measurements of the PD group at the subfoveal region and 1.5 mm temporal and 1.5 mm nasal to the fovea were 228.1 ± 44.3, 193.2 ± 41.4 and 188.4 ± 49.0 μm, respectively, whereas measurements for the controls were, respectively, 246.5 ± 38.2, 227.3 ± 34.7 and 216.7 ± 51.4 μm. The choroid was significantly thinner in eyes of the PD group compared to that of the controls (p = 0.001, p choroid thicknesses (rs[94] = -0.282, p = 0.006; rs[94] = -0.324, p = 0.001, rs[94] = -0.240, and p = 0.020, respectively). Regardless of the disease severity, PD may cause atrophy and volume loss in the lamina cribrosa, and choroid. An enhanced depth imaging technique may be used as an additional modality in the diagnosis and follow-up of patients with PD. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  16. Coherent X-Ray Diffraction Imaging of Chloroplasts from Cyanidioschyzon merolae by Using X-Ray Free Electron Laser.

    Science.gov (United States)

    Takayama, Yuki; Inui, Yayoi; Sekiguchi, Yuki; Kobayashi, Amane; Oroguchi, Tomotaka; Yamamoto, Masaki; Matsunaga, Sachihiro; Nakasako, Masayoshi

    2015-07-01

    Coherent X-ray diffraction imaging (CXDI) is a lens-less technique for visualizing the structures of non-crystalline particles with the dimensions of submicrometer to micrometer at a resolution of several tens of nanometers. We conducted cryogenic CXDI experiments at 66 K to visualize the internal structures of frozen-hydrated chloroplasts of Cyanidioschyzon merolae using X-ray free electron laser (XFEL) as a coherent X-ray source. Chloroplast dispersed specimen disks at a number density of 7/(10×10 µm(2)) were flash-cooled with liquid ethane without staining, sectioning or chemical labeling. Chloroplasts are destroyed at atomic level immediately after the diffraction by XFEL pulses. Thus, diffraction patterns with a good signal-to-noise ratio from single chloroplasts were selected from many diffraction patterns collected through scanning specimen disks to provide fresh specimens into the irradiation area. The electron density maps of single chloroplasts projected along the direction of the incident X-ray beam were reconstructed by using the iterative phase-retrieval method and multivariate analyses. The electron density map at a resolution of 70 nm appeared as a C-shape. In addition, the fluorescence image of proteins stained with Flamingo™ dye also appeared as a C-shape as did the autofluorescence from Chl. The similar images suggest that the thylakoid membranes with an abundance of proteins distribute along the outer membranes of chloroplasts. To confirm the present results statistically, a number of projection structures must be accumulated through high-throughput data collection in the near future. Based on the results, we discuss the feasibility of XFEL-CXDI experiments in the structural analyses of cellular organelles. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  17. Optical coherence elastography for cellular-scale stiffness imaging of mouse aorta

    Science.gov (United States)

    Wijesinghe, Philip; Johansen, Niloufer J.; Curatolo, Andrea; Sampson, David D.; Ganss, Ruth; Kennedy, Brendan F.

    2017-04-01

    We have developed a high-resolution optical coherence elastography system capable of estimating Young's modulus in tissue volumes with an isotropic resolution of 15 μm over a 1 mm lateral field of view and a 100 μm axial depth of field. We demonstrate our technique on healthy and hypertensive, freshly excised and intact mouse aortas. Our technique has the capacity to delineate the individual mechanics of elastic lamellae and vascular smooth muscle. Further, we observe global and regional vascular stiffening in hypertensive aortas, and note the presence of local micro-mechanical signatures, characteristic of fibrous and lipid-rich regions.

  18. Optical Coherence Tomography Imaging of Choroidal Abnormalities in Neurofibromatosis Type 1

    Directory of Open Access Journals (Sweden)

    Shinji Makino

    2013-01-01

    Full Text Available We report a case of neurofibromatosis type 1 (NF1 examined by infrared fundus autofluorescence (IR-FAF and optical coherence tomography (OCT to characterize the associated choroidal abnormalities. The conventional ophthalmoscopic findings were unremarkable. However, IR-FAF revealed multiple bright patchy lesions in the choroid of the posterior pole, in both eyes. OCT demonstrated irregular hyperreflectivity at the sites of these lesions. Patients with NF1 may have typical choroidal lesions that are visible on IR-FAF, which can be confirmed through OCT.

  19. X-ray imaging by partially coherent synchrotron light. Application to metallic alloys, tooth dentin and natural rock

    Energy Technology Data Exchange (ETDEWEB)

    Zabler, Simon Andreas

    2007-10-09

    The hard spectrum which is available on the BAMline at Berlin's synchrotron BESSY offers the rare opportunity to perform high-resolution X-ray imaging experiments with a partially coherent beam. This thesis work reports on the development of a new tomography system, including Fresnel-propagated imaging, and its application to three specific materials science problems from the fields of engineering materials, biology and earth science. Static and dynamic 2D and 3D images were recorded from a variety of aluminum-based alloys. Coarsening of particle agglomerates (at high solid volume fraction) in liquid solution, as well as rheological properties of semi-solid alloys are thus characterized. Dentin is characterized by a quasi-parallel arrangement of micrometer-sized tubules. This work shows how high-resolution 3D images of water-immersed tooth dentin are recorded, and detailed simulations of the optical wave propagation reveal that Fresnel-images contain additional information about the dense cuff of peritubular dentin surrounding the tubules. The cuff thickness can be extrapolated from the interference fringes that form the propagated images of tubules. Absorption and Fresnel-propagated X-ray tomography are applied to measure samples of different rocks before and after mechanical compression nondestructively. In a first approach, limestone and greywacke are investigated, representing two sedimentary rocks of different grain size. Basalt and granite are tested in a second approach to compare different rock types. Development of cracks is observed in all materials, leading to fracture when increasing mechanical load is applied. In this work, relatively small mm-sized samples are used in order to test a classical fracture model wherein micro-flaws initiate the formation of larger cracks. For the first time, Fresnel-propagated imaging is applied to rock samples, highlighting micrometer-sized intergranular porosity as well as different material phases. The latter is

  20. Change in Drusen Area Over Time Compared Using Spectral-Domain Optical Coherence Tomography and Color Fundus Imaging

    Science.gov (United States)

    Gregori, Giovanni; Yehoshua, Zohar; Garcia Filho, Carlos Alexandre de Amorim; Sadda, SriniVas R.; Portella Nunes, Renata; Feuer, William J.; Rosenfeld, Philip J.

    2014-01-01

    Purpose. To investigate the relationship between drusen areas measured with color fundus images (CFIs) and those with spectral-domain optical coherence tomography (SDOCT). Methods. Forty-two eyes from thirty patients with drusen in the absence of geographic atrophy were recruited to a prospective study. Digital color fundus images and SDOCT images were obtained at baseline and at follow-up visits at 3 and 6 months. Registered, matched circles centered on the fovea with diameters of 3 mm and 5 mm were identified on both CFIs and SDOCT images. Spectral-domain OCT drusen measurements were obtained using a commercially available proprietary algorithm. Drusen boundaries on CFIs were traced manually at the Doheny Eye Institute Image Reading Center. Results. Mean square root drusen area (SQDA) measurements for the 3-mm circles on the SDOCT images were 1.451 mm at baseline and 1.464 mm at week 26, whereas the measurements on CFIs were 1.555 mm at baseline and 1.584 mm at week 26. Mean SQDA measurements from CFIs were larger than those from the SDOCT measurements at all time points (P = 0.004 at baseline, P = 0.003 at 26 weeks). Changes in SQDA over 26 weeks measured with SDOCT were not different from those measured with CFIs (mean difference = 0.014 mm, P = 0.5). Conclusions. Spectral-domain OCT drusen area measurements were smaller than the measurements obtained from CFIs. However, there were no differences in the change in drusen area over time between the two imaging modalities. Spectral-domain OCT measurements were considerably more sensitive in assessing drusen area changes. PMID:25335982