1. Articles from ping xue

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    1. 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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    2. 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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    3. 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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    4. 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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    5. Endoscopic optical coherence tomography with a focus-adjustable probe

      Endoscopic optical coherence tomography with a focus-adjustable probe

      We present a focus-adjustable endoscopic probe for optical coherence tomography (OCT), which is able to acquire images with different focal planes and overcome depth-of-focus limitations by image fusing. The use of a two-way shape-memory-alloy spring enables the probe to adjust working distance over 1.5 mm, providing a large scanning range with high resolution and no sensitivity loss. Equipped with a homemade hollow-core ultrasonic motor, the probe is capable of performing an unobstructed 360 deg field-of-view distal scanning. Both the axial resolution and the best lateral resolution are ∼ 4    μm ∼4  μm , with a sensitivity of 100.3 dB. Spectral-domain ...

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    6. Feature Of The Week 11/26/2016: Tsinghua University Demonstrates Optical Computing Technique and Achieves High Speed OCT of 10 Mega-A-Scans/Second.

      Feature Of The Week 11/26/2016: Tsinghua University Demonstrates Optical Computing Technique and Achieves High Speed OCT of 10 Mega-A-Scans/Second.

      In the past few decades, OCT has been applied in a wide range of applications including clinical and material research areas. For some biomedical applications such as surgical guidance, real-time volumetric OCT (4D-OCT) imaging is in high demand. However, for high definition volumetric imaging in real time, i.e., 1000 pixels along 3 spatial dimensions and 30 volumetric imaging per second, the data flow will be 1000×1000×1000×30=30GVoxel/s. To process these massive data is a big challenge to the performance of current GPUs and CPUs. Professor Ping Xue, Postdoc Xiao Zhang and their colleagues from Tsinghua ...

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    7. Optical computing for optical coherence tomography

      Optical computing for optical coherence tomography

      We propose an all-optical Fourier transformation system for real-time massive data processing in high speed optical coherence tomography (OCT). In the so-called optical computing OCT, fast Fourier transformation (FFT) of A-scan signal is optically processed in real time before being detected by photoelectric detector. Therefore, the processing time for interpolation and FFT in traditional Fourier domain OCT can be dramatically eliminated. A processing rate of 10 mega-A-scans/second was experimentally achieved, which is, to our knowledge, the highest speed for OCT imaging. Due to its fiber based all-optical configuration, this optical computing OCT system is ideal for ultrahigh speed volumetric ...

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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. Ultrahigh-resolution optical coherence tomography at 1.3 μm central wavelength by using a supercontinuum source pumped by noise-like pulses

      Ultrahigh-resolution optical coherence tomography at 1.3 μm central wavelength by using a supercontinuum source pumped by noise-like pulses

      We report on the ultrahigh-resolution optical coherence tomography (OCT) with a novel high-power supercontinuum (SC) light source generated by noise-like pulses from an Yb-doped fiber laser. The SC spectrum is flat with a bandwidth of 420 nm centered around ~1.3 μ m. The light source is successfully employed in a time-domain OCT (TD-OCT), achieving an axial resolution of 2.3 μ m. High resolution fiber-based spectral-domain OCT (SD-OCT) imaging of bio-tissue was also demonstrated.

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    10. Ultrahigh-speed optical coherence tomography utilizing all-optical 40 MHz swept-source

      Ultrahigh-speed optical coherence tomography utilizing all-optical 40 MHz swept-source

      We present an ultrahigh-speed optical coherence tomography (OCT) based on an all-optical swept-source with an A-scan rate of 40 MHz. The inertia-free swept-source, which has its output power of 41.2 mW and tuning range of 40 nm and high scan linearity in wavenumber with Pearson’s correlation coefficients r of 0.9996, consists of a supercontinuum laser, an optical band-pass filter, a linearly chirped fiber Bragg grating, an erbium-doped fiber amplifier, and two buffer stages. With sensitivity of 87 dB, high-speed OCT imaging of biological tissue in vivo is also demonstrated.

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    11. 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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    12. 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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    13. 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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    14. 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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    15. 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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    16. 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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    17. Speckle-constrained variational methods for image restoration in optical coherence tomography

      Speckle-constrained variational methods for image restoration in optical coherence tomography

      A number of despeckling methods for optical coherence tomography (OCT) have been proposed. In these digital filtering techniques, speckle noise is often simplified as additive white Gaussian noise due to the logarithmic compression for the signal. The approximation is not completely consistent with the characteristic of OCT speckle noise, and cannot be reasonably extended to deconvolution algorithms. This paper presents a deconvolution model that combines the variational regularization term with the statistical characteristic constraints of data corrupted by OCT speckle noise. In the data fidelity term, speckle noise is modeled as signal dependent, and the point spread function of OCT ...

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    18. OCT News 2013 Student Paper Awarded to Jing-gao Zheng from Tsinghua University

      OCT News 2013 Student Paper Awarded to Jing-gao Zheng from Tsinghua University

      Jing-Gao Zheng from Tsinghua University was a winner of the 2013 OCT News Student Paper Award for his submission “Understanding early patterning and polarity of preimplantation mouse embryos with full-field optical coherence tomography.” Below is a summary of his work:  Morphogenetic relationship between early patterning and the polarity formation is of fundamental interest and remains controversial issues in mammalian preimplantation development. Label-free subcellular 3D live imaging technique is very helpful to its related studies. We have developed a novel system of full-field optical coherence tomography (FF-OCT) for non-invasive 3D sub-cellular live imaging of preimplantation mouse embryos with no need of ...

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    19. 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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    20. Imaging of skin microvessels with optical coherence tomography: potential uses in port wine stains

      Imaging of skin microvessels with optical coherence tomography: potential uses in port wine stains

      The knowledge of vascular structures of port wine stains (PWSs) may be useful to select treatment doses and improve therapeutic efficacy. Biopsies are impractical to implement, therefore, it is necessary to develop non-invasive techniques for morphological evaluation. This study aimed to evaluate the application of a novel optical coherence tomography (OCT) system to characterize the vascular structures of PWSs. First, OCT images were obtained from the skin of healthy rabbit ears and compared with the histopathological images. Second, OCT was used to document the differences between PWS lesions and contralateral normal skin; the size and depth of the vascular structures ...

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    21. 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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    22. 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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    23. 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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    24. 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. (30 articles) Ping Xue
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    Imaging port wine stains by fiber optical coherence tomography 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 OCT News 2013 Student Paper Awarded to Jing-gao Zheng from Tsinghua University Feature Of The Week 10/13/13: Tsinghua University Demonstrates a Tiny OCT Endoscopic Probe Using a Hollow Ultrasonic Motor 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 11/26/2016: Tsinghua University Demonstrates Optical Computing Technique and Achieves High Speed OCT of 10 Mega-A-Scans/Second. Intravitreal Ranibizumab Monotherapy or Combined with Laser for Diabetic Macular Edema (OCT guided study) Prospective evaluation of drug eluting self‐apposing stent for the treatment of unprotected left main coronary artery disease: 1‐year results of the TRUNC study Clinical validation of the RTVue optical coherence tomography angiography image quality indicators Intraoperative OCT-Assisted Retinal Detachment Repair in the DISCOVER Study: Impact and Outcomes Analysis of Retinal Vascular Density using Optical Coherence Tomography Angiography, to Differentiate Healthy, Glaucoma Suspect and Glaucomatous Eyes (Thesis)