1. Articles from xuan liu

    1-24 of 39 1 2 »
    1. Spectral 3D reconstruction of impressionist oil paintings based on macroscopic OCT imaging

      Spectral 3D reconstruction of impressionist oil paintings based on macroscopic OCT imaging

      Art conservators have adopted optical technologies to improve conservation efforts; laser triangulation, stereophotogrammetry, structured light, laser scanners, and time of flight sensors have been deployed to capture the 3D information of sculptures and architectures. Optical coherence tomography (OCT) has introduced new imaging methods to study the surface features and subsurface structures of delicate cultural heritage objects. However, the field of view of OCT severely limits the scanning area. We present a hybrid scanning platform combined with an effective algorithm for real-time sampling and artifact removal to achieve macroscopic OCT (macro-OCT) imaging and spectral 3D reconstruction of impressionist style oil paintings.

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      Mentions: Yi Yang
    2. Optically computed optical coherence tomography for volumetric imaging

      Optically computed optical coherence tomography for volumetric imaging

      We describe an innovative optically computed optical coherence tomography (OC-OCT) technology. The OC-OCT system performs depth resolved imaging by computing the Fourier transform of the interferometric spectra optically. The OC-OCT system modulates the interferometric spectra with Fourier basis function projected to a spatial light modulator and detects the modulated signal without spectral discrimination. The novel, to the best of our knowledge, optical computation strategy enables volumetric OCT imaging without performing mechanical scanning and without the need for Fourier transform in a computer.

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      Mentions: Xuan Liu
    3. Spatial coordinate corrected motion tracking for optical coherence elastography

      Spatial coordinate corrected motion tracking for optical coherence elastography

      We investigate a spatial coordinate correction (SCC) method to track motion with high accuracy for optical coherence elastography (OCE). Through SCC, we refer the displacement field tracked by optical coherence tomography (OCT) in the loaded sample to individual material points defined in a fixed coordinate system. SCC allows OCE to perform spatially and temporally unambiguous tracking of displacement and enables accurate mechanical characterization of biological tissue for cancer diagnosis and tumor margin assessment. In this study, we validated the effectiveness of motion tracking based on SCC using experimental OCE data obtained from ex vivo human breast tissues.

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    4. Assessment and removal of additive noise in a complex optical coherence tomography signal based on Doppler variation analysis

      Assessment and removal of additive noise in a complex optical coherence tomography signal based on Doppler variation analysis

      In this study, we investigate and validate a novel approach to assess and remove additive noise for optical coherence tomography (OCT) imaging. Our method first generates a map of additive noise for the OCT image through Doppler variation analysis. We then remove the additive noise from the real and imaginary parts of the complex OCT signal through pixelwise Wiener filtering. Our results show that the method described in this manuscript improves the sensitivity of OCT imaging and preserves the spatial resolution without the need to modify the imaging apparatus and data acquisition protocol.

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      Mentions: Xuan Liu
    5. Noise adaptive wavelet thresholding for speckle noise removal in optical coherence tomography

      Noise adaptive wavelet thresholding for speckle noise removal in optical coherence tomography

      Optical coherence tomography (OCT) is based on coherence detection of interferometric signals and hence inevitably suffers from speckle noise. To remove speckle noise in OCT images, wavelet domain thresholding has demonstrated significant advantages in suppressing noise magnitude while preserving image sharpness. However, speckle noise in OCT images has different characteristics in different spatial scales, which has not been considered in previous applications of wavelet domain thresholding. In this study, we demonstrate a noise adaptive wavelet thresholding (NAWT) algorithm that exploits the difference of noise characteristics in different wavelet sub-bands. The algorithm is simple, fast, effective and is closely related to ...

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    6. Secure fingerprint identification based on structural and microangiographic optical coherence tomography

      Secure fingerprint identification based on structural and microangiographic optical coherence tomography

      Optical coherence tomography (OCT) allows noncontact acquisition of fingerprints and hence is a highly promising technology in the field of biometrics. OCT can be used to acquire both structural and microangiographic images of fingerprints. Microangiographic OCT derives its contrast from the blood flow in the vasculature of viable skin tissue, and microangiographic fingerprint imaging is inherently immune to fake fingerprint attack. Therefore, dual-modality (structural and microangiographic) OCT imaging of fingerprints will enable more secure acquisition of biometric data, which has not been investigated before. Our study on fingerprint identification based on structural and microangiographic OCT imaging is, we believe, highly ...

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    7. Optical coherence tomography for non-invasive examination and conservation of cultural heritage objects

      Optical coherence tomography for non-invasive examination and conservation of cultural heritage objects

      Optical coherence tomography (OCT) has great potential for the examination of oil paintings, particularly for celebrated masterpieces by great artists in history. We developed an OCT system for large field of view (FOV), high definition (HD) imaging of oil paintings. To achieve large FOV, we translated the sample using a pair of high-precision linear motors and performed sequential volumetric imaging on adjacent, non-overlapping regions. Through 3D OCT imaging, the surface terrain and subsurface microarchitecture of the paintings have been characterized and visualized.

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    8. High-definition optical coherence tomography imaging for noninvasive examination of heritage works

      High-definition optical coherence tomography imaging for noninvasive examination of heritage works

      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 ...

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    9. Optical coherence tomography systems and methods with magnitude and direction tracking of transverse motion

      Optical coherence tomography systems and methods with magnitude and direction tracking of transverse motion

      An optical coherence tomography (OCT) system having magnitude and direction of motion detection has a light source, and a scanning system arranged in an optical path of the light source. The scanning system is configured to scan an illumination beam of light in a spatial pattern around each of a plurality of points of interest of an object under observation for a corresponding plurality of instants of time in which each of the plurality of points of interest are displaced from each other due to motion of at least one of the OCT system or the object under observation. The ...

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    10. Quantitative optical coherence elastography based on fiber-optic probe for in situ measurement of tissue mechanical properties

      Quantitative optical coherence elastography based on fiber-optic probe for in situ measurement of tissue mechanical properties

      We developed a miniature quantitative optical coherence elastography (qOCE) instrument with an integrated Fabry-Perot force sensor, for in situ elasticity measurement of biological tissue. The technique has great potential for biomechanics modeling and clinical diagnosis. We designed the fiber-optic qOCE probe that was used to exert a compressive force to deform tissue at the tip of the probe. Using the space-division multiplexed optical coherence tomography (OCT) signal detected by a spectral domain OCT engine, we were able to quantify the probe deformation that was proportional to the force applied, and to quantify the tissue deformation corresponding to the external stimulus ...

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      Mentions: Xuan Liu
    11. Lateral distortion corrected optical coherence tomography system

      Lateral distortion corrected optical coherence tomography system

      A lateral-distortion corrected optical coherence tomography system. The system can include an optical coherence tomography sensor, a light source, a fiber-optic system arranged to provide a reference beam and an observation beam, an optical detection system arranged to receive combined light from the reference beam and the observation beam and to provide detection signals, and a data processing system arranged to communicate with the optical detection system and receive the detection signals. The data processing system can be configured to assemble an image corresponding to a scanning path by constructing a plurality of A-scans from the detection signals, determining displacement ...

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    12. Interferometric force sensor for surgical instruments

      Interferometric force sensor for surgical instruments

      A surgical tool system according to an embodiment of the current invention includes a surgical tool, and an interferometry system optically coupled to the surgical tool. The surgical tool includes a body section, a sensor section at least one of attached to or integral with the body section, and a surgical section at least one of attached to or integral with the sensor section at an opposing end of the sensor section from the body section. The sensor section comprises an interferometric optical sensor defining a reference distance that changes in response to at least one of a force or ...

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    13. Robust motion tracking based on adaptive speckle decorrelation analysis of OCT signal

      Robust motion tracking based on adaptive speckle decorrelation analysis of OCT signal

      Speckle decorrelation analysis of optical coherence tomography (OCT) signal has been used in motion tracking. In our previous study, we demonstrated that cross-correlation coefficient (XCC) between Ascans had an explicit functional dependency on the magnitude of lateral displacement ( δx ). In this study, we evaluated the sensitivity of speckle motion tracking using the derivative of function XCC( δx ) on variable δx . We demonstrated the magnitude of the derivative can be maximized. In other words, the sensitivity of OCT speckle tracking can be optimized by using signals with appropriate amount of decorrelation for XCC calculation. Based on this finding, we developed an ...

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      Mentions: Xuan Liu
    14. Motion analysis and removal in intensity variation based OCT angiography

      Motion analysis and removal in intensity variation based OCT angiography

      In this work, we investigated how bulk motion degraded the quality of optical coherence tomography (OCT) angiography that was obtained through calculating interframe signal variation, i.e., interframe signal variation based optical coherence angiography (isvOCA). We demonstrated theoretically and experimentally that the spatial average of isvOCA signal had an explicit functional dependency on bulk motion. Our result suggested that the bulk motion could lead to an increased background in angiography image. Based on our motion analysis, we proposed to reduce image artifact induced by transient bulk motion in isvOCA through adaptive thresholding. The motion artifact reduced angiography was demonstrated in ...

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      Mentions: Xuan Liu
    15. Durable Single Mode Fiber Probe With Optimized Reference Reflectivity

      Durable Single Mode Fiber Probe With Optimized Reference Reflectivity

      A probe for a common path optical coherence tomography system includes a sheath having a proximal end and a distal end and defining a lumen therein, a single mode optical fiber disposed within the lumen of the sheath such that a portion of the single mode optical fiber extends beyond the distal end of the sheath. The single mode optical fiber has an end face for transmitting and receiving light. The probe also includes a layer of hardened epoxy encasing the portion of the single mode optical fiber that extends beyond the distal end of the sheath except for the ...

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    16. Distortion Corrected Optical Coherence Tomography System

      Distortion Corrected Optical Coherence Tomography System

      An axial motion distortion-corrected optical coherence tomography system. The system can include an optical coherence tomography sensor, a light source, a fiber-optic system arranged to provide a reference beam and an observation beam, an optical detection system arranged to receive combined light from the reference beam and the observation beam and to provide detection signals, and a data processing system arranged to receive said detection signals, construct a plurality of A-scans from said detection signals, and construct one or more images from said plurality of A-scans. The data processing system can be configured to correct distortion in the images caused ...

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    17. Postdoctoral Fellow Opening in Electrical and Computer Engineering Department at New Jersey Institute of Technology

      Postdoctoral Fellow Opening in Electrical and Computer Engineering Department at New Jersey Institute of Technology

      A postdoc position in biomedical optics is available at Electrical and Computer Engineering Department at New Jersey Institute of Technology. The successful candidate will work on highly innovative projects focused on the development of miniature optical coherence tomography (OCT) device for imaging and functional information extraction. Requirements: A doctorate degree in Optics, Physics, Biomedical Engineering, Electrical Engineering, or related fields is required. It is desirable to be experienced in one or more of the following areas: fiber optics; design and alignment of optical imaging system; microscopy; signal processing; programming in C/C++/Matlab/Labview. Expertise of OCT is preferred but ...

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      Mentions: Xuan Liu
    18. Improvement of optical coherence tomography using active handheld micromanipulator in vitreoretinal surgery

      Improvement of optical coherence tomography using active handheld micromanipulator in vitreoretinal surgery

      An active handheld micromanipulator has been developed to cancel hand tremor during microsurgery. The micromanipulator is also applicable in optical coherence tomography to improve the quality of scanning and minimize surgical risks during the scans. The manipulator can maneuver the tool tip with six degrees of freedom within a cylindrical workspace 4 mm in diameter and 4 mm high. The imaging system is equipped with a 25-gauge Fourier-domain common-path OCT probe. This paper introduces the handheld OCT imaging system and techniques involved and presents stabilized OCT images of A-mode and M-mode scans in air and live rabbit eyes. We show ...

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    19. Optimization of an angled fiber probe for common-path optical coherence tomography

      Optimization of an angled fiber probe for common-path optical coherence tomography

      We studied the optimization of common-path optical coherence tomography (CP OCT) sensitivity through an angled fiber probe. The magnitude of reference power derived from the tip of the fiber was optimized through careful selection of the polishing angle. We experimentally measured the signal-to-noise ratio (SNR) at different polishing angles to validate the effectiveness of this technique. We also obtained OCT images with the reference optimized CP OCT with more than 8 dB improvement in SNR.

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    20. Lateral Distortion Corrected Optical Coherence Tomography System

      Lateral Distortion Corrected Optical Coherence Tomography System

      A lateral-distortion corrected optical coherence tomography system. The system can include an optical coherence tomography sensor, a light source, a fiber-optic system arranged to provide a reference beam and an observation beam, an optical detection system arranged to receive combined light from the reference beam and the observation beam and to provide detection signals, and a data processing system arranged to communicate with the optical detection system and receive the detection signals. The data processing system can be configured to assemble an image corresponding to a scanning path by constructing a plurality of A-scans from the detection signals, determining displacement ...

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    21. Quantitative transverse flow measurement using optical coherence tomography speckle decorrelation analysis

      Quantitative transverse flow measurement using optical coherence tomography speckle decorrelation analysis

      We propose an inter-Ascan speckle decorrelation based method that can quantitatively assess blood flow normal to the direction of the optical coherence tomography imaging beam. To validate this method, we performed a systematic study using both phantom and in vivo animal models. Results show that our speckle analysis method can accurately extract transverse flow speed with high spatial and temporal resolution.

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    22. Robust spectral-domain optical coherence tomography speckle model and its cross-correlation coefficient analysis

      Robust spectral-domain optical coherence tomography speckle model and its cross-correlation coefficient analysis

      In this study, we propose a generic speckle simulation for optical coherence tomography (OCT) signal, by convolving the point-spread function (PSF) of the OCT system with the numerically synthesized random sample field. We validate our model and use the simulation method to study the statistical properties of cross-correlation coefficients between A-scans, which have been recently applied in transverse motion analysis by our group. The results of simulation show that oversampling is essential for accurate motion tracking; exponential decay of OCT signal leads to an underestimate of motion that can be corrected; lateral heterogeneity of sample leads to an overestimate of ...

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    23. Motion-compensated hand-held common-path Fourier-domain optical coherence tomography probe for image-guided intervention

      Motion-compensated hand-held common-path Fourier-domain optical coherence tomography probe for image-guided intervention

      A motion-compensated, hand-held, common-path, Fourier-domain optical coherence tomography imaging probe has been developed for image-guided intervention during microsurgery. A hand-held prototype instrument was achieved by integrating an imaging fiber probe inside a stainless steel needle and attached to the ceramic shaft of a piezoelectric motor housed in an aluminum handle. The fiber probe obtains A-scan images. The distance information was extracted from the A-scans to track the sample surface distance and a fixed distance was maintained by a feedback motor control which effectively compensated hand tremor and target movements in the axial direction. Real-time data acquisition, processing, motion compensation, and ...

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    24. Optical coherence tomography scanning with a handheld vitreoretinal micromanipulator

      Optical coherence tomography scanning with a handheld vitreoretinal micromanipulator

      An active handheld micromanipulator has been developed that is capable of automated intraocular acquisition of B-mode and C-mode optical coherence tomography scans that are up to 4 mm wide. The manipulator is a handheld Gough-Stewart platform actuated by ultrasonic linear motors. The manipulator has been equipped with a Fourier-domain common-path intraocular OCT probe that fits within a 25-gauge needle. The paper describes the systems and techniques involved, and presents preliminary results of B-mode and C-mode scans.

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    1-24 of 39 1 2 »
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    1. (36 articles) Xuan Liu
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