1. Articles from Ning Zhang

    1-20 of 20
    1. Machine-Learning Classification of Port Wine Stain With Quantitative Features of Optical Coherence Tomography Image

      Machine-Learning Classification of Port Wine Stain With Quantitative Features of Optical Coherence Tomography Image

      Port wine stain (PWS) is the benign congenital capillary malformation of skin, occurring in 0.3% to 0.5% of the population. In this paper, we build two automated support vector machine (SVM) based classifiers by extracting quantitative features from normal and PWS tissue images recorded by optical coherence tomography (OCT). We use both full feature set and simplified feature set for training. Accuracy of 92.7%, sensitivity of 92.3% and specificity of 93.8% were obtained for classifier with full feature set. Accuracy of 92.7%, sensitivity of 94.9% and specificity of 87.5% were obtained for ...

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    2. Separation of Overlapping Fingerprints in Multilayered Carrier Using Optical Coherence Tomography

      Separation of Overlapping Fingerprints in Multilayered Carrier Using Optical Coherence Tomography

      Fingerprints lifted from crime scenes are often overlapped because of multiple impressions of fingers. Current methods to separate overlapping fingerprints are primarily based on algorithms that estimate the orientation field of component prints. However, these methods need human intervention, and the accuracy of the separation may easily be degraded. In this paper, a novel tomographic imaging technique, optical coherence tomography (OCT), was used to separate overlapping fingerprints intuitively and noninvasively. The OCT system was also applied to reveal a hidden blood fingerprint that was completely covered by one layer of nontransparent paint. An additional experiment was conducted using a piece ...

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    3. Feature Of The Week 07/22/2019: Tsinghua University Demonstrates A “Sparse Sampled” Smart CCD Camera for Compressed Sensing Optical Coherence Tomography.

      Feature Of The Week 07/22/2019: Tsinghua University Demonstrates A “Sparse Sampled” Smart CCD Camera for Compressed Sensing Optical Coherence Tomography.

      Optical coherence tomography (OCT) is a promising imaging technique in medicine and biology, which allows for obtaining high-resolution, cross-sectional images of biological tissues. In the past decade, the imaging speed of OCT is consistently increasing, and currently OCT can acquire three-dimensional (3D) images in real time with imaging speed up to 10-MHz A-scan rate. With such a high imaging rate, OCT system has to acquire a large amount of data, which is too massive for data transmission and storage. Compressed sensing (CS) technique is a powerful method to solve this problem. It exploits the sparsity property of the signal and ...

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    4. Compressed sensing spectral domain optical coherence tomography with a hardware sparse-sampled camera

      Compressed sensing spectral domain optical coherence tomography with a hardware sparse-sampled camera

      We present a sparse-sampled camera for compressed sensing spectral domain optical coherence tomography (CS SD-OCT), which is mainly composed of a novel mask with specially designed coating and a commercially available CCD camera. The sparse-sampled camera under-samples the SD-OCT spectrum in hardware, thus reduces the acquired image data and can achieve faster A-scan speed than conventional CCD camera with the same pixel number. Compared with a conventional SD-OCT system, the CS SD-OCT system equipped with the sparse-sampled camera has better fall-off and SNR performance. CS-OCT imaging of bio-tissue is also demonstrated.

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    5. Optical computing optical coherence tomography with conjugate suppression by dispersion

      Optical computing optical coherence tomography with conjugate suppression by dispersion

      For all imaging techniques, such as optical coherence tomography (OCT), fast imaging speed is always of high demand. Optical computing OCT ( OC2T) has achieved ultrahigh speed for real time 3D imaging without post data processing, but its spatial resolution is lowered down due to an imperfect Fourier transformation in the optical computing process. In this Letter, we illustrate the theory of OC2T and prove that the dispersion imbalance between reference arm and sample arm may be introduced to improve the resolution. Furthermore, this novel OC2T technique can also enable a conjugate restrained OCT imaging without any data processing, achieving ∼ 2 ...

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    6. Detection of Latent Fingerprint Hidden Beneath Adhesive Tape by Optical Coherence Tomography

      Detection of Latent Fingerprint Hidden Beneath Adhesive Tape by Optical Coherence Tomography

      Adhesive tape is one type of common item which can be encountered in criminal cases involving rape, murder, kidnapping and explosives. It is often the case that a suspect deposits latent fingerprints on the sticky side of adhesive tape material when tying up victims, manufacturing improvised explosive devices or packaging illegal goods. However, the adhesive tapes found at crime scenes are usually stuck together or attached to a certain substrate, and thus the latent fingerprints may be hidden beneath the tapes. Current methods to detect latent fingerprint hidden beneath adhesive tape need to peel it off first and then apply ...

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    7. Conjugate transformation for dispersion compensation in optical coherence tomography imaging

      Conjugate transformation for dispersion compensation in optical coherence tomography imaging

      In optical coherence tomography (OCT), the sample dispersion tends to increase the signal width and hence lower down the resolution, resulting in serious image quality degradation, especially for imaging over a large depth range or media with large dispersion coefficient. In this letter, instead of the conventional Fourier transformation for dispersion compensation that can compensate the image only ideally at a certain depth, a novel transformation, as called conjugate transformation, is proposed to achieve high resolution at all depth by utilizing the conjugate function of the signal itself as an optimized integral kernel. A large dispersion media of ZnSe is ...

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    8. Characterization of Automotive Paint by Optical Coherence Tomography

      Characterization of Automotive Paint by Optical Coherence Tomography

      Automotive paint is a common trace evidence that plays a significant role in many vehicle-related criminal cases. However, the conventional methods of obtaining tomographic images tend to damage the samples. Optical coherence tomography (OCT) is a novel method to obtain high-resolution, and cross-sectional images of the automotive paints in a non-destructive, and high-speed manner. In this study, OCT was applied to image and analyze the automotive paint, using Scanning Electron Microscope (SEM) as reference. Eight automotive paint samples of different brands were examined. The images of multi-layer structures provided by OCT system with 5 μm depth resolution were consistent with ...

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    9. A preliminary study on the identification of vehicle paint chip based on optical coherence tomography

      A preliminary study on the identification of vehicle paint chip based on optical coherence tomography

      Vehicle paint chip is a common evidence that plays a significant role in many criminal cases. This paper introduced a novel imaging technology - optical coherence tomography (OCT), which can realize non-invasive, rapid, high-resolution and cross-sectional imaging for the identification of vehicle paint chips. In this paper, a 1310nm swept-source OCT system was adopted to implement the paint imaging. The results show that, compared with conventional spectroscopy and SEM methods, OCT technology can directly obtain the tomographic images of the paints without slicing. In addition, the optical attenuation properties were analyzed to provide a new feature for separating different paint samples ...

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      Mentions: Ning Zhang
    10. Feature Of The Week 2/2/14: Tsinghua University.Demonstrates Linear-in-Wavenumber Swept Laser with an Acousto-Optic Deflector for OCT

      Feature Of The Week 2/2/14: Tsinghua University.Demonstrates Linear-in-Wavenumber Swept Laser with an Acousto-Optic Deflector for OCT

      Compared to the conventional time domain OCT, the frequency domain (FD) detection techniques enable a dramatic increase in imaging speed. Spectrometer-based FD-OCT (SD-OCT) systems are already widely used, especially for ophthalmic application in the 800 nm wavelength range. Alternatively, the application of FD-OCT systems based on a rapidly swept, narrowband light source, i.e. swept source OCT (SS-OCT) offers the additional advantages of dual balance detection, potentially longer ranging depth and higher imaging speeds. However, a general disadvantage of most FD-OCT systems is the requirement to resample and recalibrate the detected OCT interference fringe prior to fast Fourier transformation, in ...

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    11. Linear-in-wavenumber swept laser with an acousto-optic deflector for optical coherence tomography

      Linear-in-wavenumber swept laser with an acousto-optic deflector for optical coherence tomography

      We report a novel linear-in-wavenumber ( k -linear) swept laser source based on an acousto-optic deflector (AOD). The AOD-based optical filter includes an acousto-optic deflector and a reflection grating. The laser may tune k linearly in wavenumber over time due to its appropriate configuration and is favorable for fast imaging because it avoids data resampling and recalibration, as are required in conventional swept source optical coherence tomography (SS-OCT). We achieved k -linearity with Pearson’s r correlation coefficients of 0.99995 without and 0.99997 with optimization. The laser has a tuning range of 50 nm, a 3 dB swept range ...

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    12. Compact piezoelectric transducer fiber scanning probe for optical coherence tomography

      Compact piezoelectric transducer fiber scanning probe for optical coherence tomography

      We developed a compact, optical fiber scanning piezoelectric transducer (PZT) probe for endoscopic and minimally invasive optical coherence tomography (OCT). Compared with previous forward-mount fiber designs, we present a reverse-mount design that achieves a shorter rigid length. The fiber was mounted at the proximal end of a quadruple PZT tube and scanned inside the hollow PZT tube to reduce the probe length. The fiber resonant frequency was 338 Hz using a 17-mm-long fiber. A 0.9 mm fiber deflection was achieved with a driving amplitude of 35 V. Using a GRIN lens-based optical design with a 1.3 × magnification, a ...

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    13. Feature Of The Week 10/13/13: Tsinghua University Demonstrates a Tiny OCT Endoscopic Probe Using a Hollow Ultrasonic Motor

      Feature Of The Week 10/13/13: Tsinghua University Demonstrates a Tiny OCT Endoscopic Probe Using a Hollow Ultrasonic Motor

      Optical coherence tomography (OCT) is an emerging modality for obtaining cross-sectional images. Due to limitation of the light penetration, small and high resolution probes for endoscopic OCT have been regarded as powerful tools in examining internal organs. Among them, circumferential probes are utilized extensively for imaging within hollow tissues, such as arteries, esophagus, and colon. In recent years, distal scanning is of high interest, as the whole fiber remains stationary in this case. The twisting and nonuniformity in the conventional proximal scanning are avoided. However, some problems emerge such as the wire-shadow effect and the relative large size of the ...

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    14. Tiny endoscopic optical coherence tomography probe driven by a miniaturized hollow ultrasonic motor

      Tiny endoscopic optical coherence tomography probe driven by a miniaturized hollow ultrasonic motor

      We present an endoscopic probe for optical coherence tomography (OCT) equipped with a miniaturized hollow ultrasonic motor that rotates the objective lens and provides an internal channel for the fiber to pass through, enabling 360 deg unobstructed circumferential scanning. This probe has an outer diameter of 1.5 mm, which is ultra-small for motorized probes with an unobstructed view in distal scanning endoscopic OCT. Instead of a mirror or prism, a customized aspheric right-angle lens is utilized, leading to an enlargement of the numerical aperture and thus high transverse resolution. Spectral-domain OCT imaging of bio-tissue and a phantom are demonstrated ...

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    15. Noninvasive three-dimensional live imaging methodology for the spindles at meiosis and mitosis

      Noninvasive three-dimensional live imaging methodology for the spindles at meiosis and mitosis

      The spindle plays a crucial role in normal chromosome alignment and segregation during meiosis and mitosis. Studying spindles in living cells noninvasively is of great value in assisted reproduction technology (ART). Here, we present a novel spindle imaging methodology, full-field optical coherence tomography (FF-OCT). Without any dye labeling and fixation, we demonstrate the first successful application of FF-OCT to noninvasive three-dimensional (3-D) live imaging of the meiotic spindles within the mouse living oocytes at metaphase II as well as the mitotic spindles in the living zygotes at metaphase and telophase. By post-processing of the 3-D dataset obtained with FF-OCT, the ...

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    16. Understanding three-dimensional spatial relationship between the mouse second polar body and first cleavage plane with full-field optical coherence tomography

      Understanding three-dimensional spatial relationship between the mouse second polar body and first cleavage plane with full-field optical coherence tomography

      he morphogenetic relationship between early patterning and polarity formation is of fundamental interest and remains a controversial issue in preimplantation embryonic development. We use a label-free three-dimensional (3-D) imaging technique of full-field optical coherence tomography (FF-OCT) successfully for the first time to study the dynamics of developmental processes in mouse preimplantation lives. Label-free 3-D subcellular time-lapse images are demonstrated to investigate 3-D spatial relationship between the second polar body (2PB) and the first cleavage plane. By using FF-OCT together with quantitative study, we show that only 25% of the predicted first cleavage planes, defined by the apposing plane of two ...

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    17. Feature Of The Week 7/22/12: Label-Free Subcellular 3D Live Imaging of Preimplantation Mouse Embryos With Full-Field Optical Coherence Tomography

      Feature Of The Week 7/22/12: Label-Free Subcellular 3D Live Imaging of Preimplantation Mouse Embryos With Full-Field Optical Coherence Tomography

      arly patterning and polarity is of fundamental interest in preimplantation embryonic development. Label-free subcellular 3D live imaging is very helpful to its related studies. We have developed a novel system of full-field optical coherence tomography (FF-OCT) for noninvasive 3D subcellular live imaging of preimplantation mouse embryos with no need of dye labeling. 3D digitized embryos can be obtained by image processing. Label-free 3D live imaging is demonstrated for the mouse embryos at various typical preimplantation stages with a spatial resolution of 0.7 µm and imaging rate of 24 fps. Factors that relate to early patterning and polarity, such as ...

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    18. Compressed sensing with linear-in-wavenumber sampling in spectral-domain optical coherence tomography

      Compressed sensing with linear-in-wavenumber sampling in spectral-domain optical coherence tomography

      We propose a novel method called compressed sensing with linear-in-wavenumber sampling (k -linear CS) to retrieve an image for spectral-domain optical coherence tomography (SD-OCT). An array of points that is evenly spaced in wavenumber domain is sampled from an original interferogram by a preset k -linear mask. Then the compressed sensing based on l1 norm minimization is applied on these points to reconstruct an A-scan data. To get an OCT image, this method uses less than 20% of the total data as required in the typical process and gets rid of the spectral calibration with numerical interpolation in traditional CS-OCT ...

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    19. Label-free subcellular 3D live imaging of preimplantation mouse embryos with full-field optical coherence tomography

      Label-free subcellular 3D live imaging of preimplantation mouse embryos with full-field optical coherence tomography

      Early patterning and polarity is of fundamental interest in preimplantation embryonic development. Label-free subcellular 3D live imaging is very helpful to its related studies. We have developed a novel system of full-field optical coherence tomography (FF-OCT) for noninvasive 3D subcellular live imaging of preimplantation mouse embryos with no need of dye labeling. 3D digitized embryos can be obtained by image processing. Label-free 3D live imaging is demonstrated for the mouse embryos at various typical preimplantation stages with a spatial resolution of 0.7 µm and imaging rate of 24 fps. Factors that relate to early patterning and polarity, such as ...

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    20. Spectral-domain optical coherence tomography with a Fresnel spectrometer

      Spectral-domain optical coherence tomography with a Fresnel spectrometer

      We propose a novel spectral-domain optical coherence tomography (SD-OCT) equipped with a Fresnel spectrometer, which utilizes a Fresnel zone plate (FZP) as both dispersion and focusing optics and thus spreads the spectral interferogram evenly in wavenumber domain because of the proportional relation between the focal length of the FZP and the wavenumber. With no need of the conversion calculation from wavelength to wavenumber in conventional SD-OCT, this new design is favorable for fast imaging with high resolution. As only a FZP and CCD are used, the Fresnel spectrometer is simple and compact. It is experimentally shown that its performance is ...

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    1-20 of 20
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  2. Topics in the News

    1. (20 articles) Ning Zhang
    2. (18 articles) Tsinghua University
    3. (18 articles) Chengming Wang
    4. (17 articles) Ping Xue
    5. (10 articles) Jing-gao Zheng
    6. (10 articles) Tianyuan Chen
    7. (2 articles) Peking University
    8. (2 articles) Massachusetts Institute of Technology
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    Spectral-domain optical coherence tomography with a Fresnel spectrometer Label-free subcellular 3D live imaging of preimplantation mouse embryos with full-field optical coherence tomography Compressed sensing with linear-in-wavenumber sampling in spectral-domain optical coherence tomography Feature Of The Week 7/22/12: Label-Free Subcellular 3D Live Imaging of Preimplantation Mouse Embryos With Full-Field Optical Coherence Tomography Understanding three-dimensional spatial relationship between the mouse second polar body and first cleavage plane with full-field optical coherence tomography Tiny endoscopic optical coherence tomography probe driven by a miniaturized hollow ultrasonic motor Feature Of The Week 10/13/13: Tsinghua University Demonstrates a Tiny OCT Endoscopic Probe Using a Hollow Ultrasonic Motor Compact piezoelectric transducer fiber scanning probe for optical coherence tomography Linear-in-wavenumber swept laser with an acousto-optic deflector for optical coherence tomography Feature Of The Week 2/2/14: Tsinghua University.Demonstrates Linear-in-Wavenumber Swept Laser with an Acousto-Optic Deflector for OCT Direct inverse linearization of piezoelectric actuator’s initial loading curve and its applications in full-field optical coherence tomography (FF-OCT) Peripapillary Retinal and Choroidal Perfusion in Nonarteritic Ischemic Optic Neuropathy Using Optical Coherence Tomography Angiography