1. Articles from Minghui Chen

    1-12 of 12
    1. Multiscale dual attention mechanism for fluid segmentation of optical coherence tomography images

      Multiscale dual attention mechanism for fluid segmentation of optical coherence tomography images

      Optical coherence tomography (OCT) technology can obtain a clear retinal structure map, which is greatly beneficial for the diagnosis of retinopathy. Ophthalmologists can use OCT technology to analyze information about the retina’s internal structure and changes in retinal thickness. Therefore, segmentation of retinal layers in images and screening for retinal diseases have become important goals in OCT scanning. In this paper, we propose the multiscale dual attention (MSDA)-UNet network, an MSDA mechanism network for OCT lesion area segmentation. The MSDA-UNet network introduces position and multiscale channel attention modules to calculate a global reference for each pixel prediction. The ...

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    2. Miniaturized all fiber probe for optical coherence tomography and pH detection of biological tissue

      Miniaturized all fiber probe for optical coherence tomography and pH detection of biological tissue

      We present a novel all‐fiber probe with 710‐μm outside diameter for combined optical coherence tomography and pH detection. In cancer surgery, a significant challenge is how to completely remove the malignant tumor without cutting too much normal tissue. The difference between cancer tissue and normal tissue not only lies in morphology and structure but also in tissue pH, where malignant tissue has a lower pH. This dual‐modality probe combined optical coherence tomography and pH detection of biological tissue, is expected to determine whether the tissue is cancerous quickly and accuporcine ely. The probe utilizes a typical three ...

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    3. Wavelength-swept fiber laser based on acousto-optic tuning method

      Wavelength-swept fiber laser based on acousto-optic tuning method

      In this study, we have demonstrated a wavelength-swept fiber laser based on an acousto-optic tunable filter(AOTF) as a selective element and a semiconductor optical amplifier(SOA) as a gain medium in an internal fiber ring cavity. The light deriving from one port of the SOA goes through an optical isolator, the AOTF, a fiber coupler and a polarized controller successively, then it goes back to the other port of the SOA to form a ring cavity. The laser output is from another port of the fiber coupler. The laser made by this method is mainly used for swept-source optical ...

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    4. Full-range swept source optical coherence tomography based on carrier frequency by transmissive dispersive optical delay line

      Full-range swept source optical coherence tomography based on carrier frequency by transmissive dispersive optical delay line

      A high speed swept source optical coherence tomography (SS-OCT) system capable of full-range imaging is presented. Wave-number carrier frequency is introduced into the spectral interference signal by a transmissive dispersive optical delay line (TDODL). High carrier frequency in the spectral interference signal corresponding to an equivalent distance-shift is exploited to obtain full-range OCT imaging. Theoretical development is conducted with the instantaneous coherence function introduced for a complete description of a spectral interference signal. Performance advantage of the TDODL-based method over the conventional approach where only one side (positive or negative path length difference) is used for imaging to avoid overlaying ...

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    5. Spectral phase based k-domain interpolation for uniform sampling in swept-source optical coherence tomography

      Spectral phase based k-domain interpolation for uniform sampling in swept-source optical coherence tomography

      We propose an efficient direct k-domain interpolation based on spectral phase in swept-source optical coherence tomography (SS-OCT). Both the calibration signal from the Mach-Zehnder interferometer (MZI) and the OCT imaging signal from the Michelson interferometer sharing the same swept source are detected and digitized simultaneously. Sufficient sampling of the OCT imaging signal with uniform k interval are directly interpolated in the k-domain based on the spectral phase derived from MZI calibration signal. Depth profile is then obtained from Fourier transform of the k-domain interpolated data. In vivo imaging of human finger skin and nail fold are conducted. Reconstructed images corresponding ...

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    6. Deconvolution with fall-off compensated axial point spread function in spectral domain optical coherence tomography

      Deconvolution with fall-off compensated axial point spread function in spectral domain optical coherence tomography

      A deconvolution method for image enhancement suitable for spectral domain optical coherence tomography (SD-OCT) is proposed. The method includes Wiener filtering for spectral deconvolution and successive homomorphic filtering for spatial deconvolution, aiming to minimize blurring effect of axial point spread function (PSF) and its depth dependence. Tunable factor in Wiener filtering is optimized for tradeoff between compensation ratio and signal-to-noise ratio (SNR). In vivo OCT imaging of a fresh shrimp is done and image reconstructions are performed. Comparing results demonstrates the proposed method suppresses the coherent noises in OCT image while compensating sensitivity fall-off with increased averaged SNR and recovers ...

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    7. Development of a high speed spectral domain optical coherence tomography system at 835 nm

      We develop a high speed multi-functional spectral domain (SD-OCT) system, using a broadband light source centered at 835nm and a custom-built spectrometer with a spectral resolution of 0.0674nm. After precise spectral calibration of the spectrometer, non-uniform discrete Fourier transform (NDFT) of the acquired spectral data is adopted for image reconstruction. In vivo imaging of human finger from volunteer at A-scan rate of 29 kHz with different reconstruction methods reveal that with the NDFT method, improved sensitivity fall-off especially at large depth is achieved in contrast to the conventional discrete Fourier transform (DFT) with interpolation method. And the phase information ...

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    8. Time-frequency distributions in spectroscopic Fourier-domain optical coherence tomography

      Current analysis for spectroscopic optical coherence tomography (SOCT) signals is limited by an uncertainty relationship between time (depth) and frequency (wavelength). Various joint time-frequency distributions (TFDs) can meliorate the limits to obtain the best information. Synthesized signals which correspond to three typical SOCT signals in the Fourier-domain under different SOCT imaging schemes, were generated and validate several different TFDs, including short time Fourier transform (STFT), continuous wavelet transform (CWT), Wigner-Villy distribution (WVD), and smoothed pseudo WVD (SPWVD). We found that different SOCT imaging scheme requires different optimal TFDs. STFT offers the most reliable and fast time-frequency (TF) analysis, which is ...
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    9. Sinusoidal B-M method based spectral domain optical coherence tomography for the elimination of complex-conjugate artifact

      Sinusoidal B-M method based spectral domain optical coherence tomography for the elimination of complex-conjugate artifact

      A high speed spectral domain optical coherence tomography based on the spatial sinusoidal phase modulation for the elimination of complex-conjugate artifact is presented, where sinusoidal phase modulation of reference arm (M scan) and transverse scanning of sample arm (B scan) are performed simultaneously (sinusoidal B-M method). Herein, the linear phase modulation of the reference arm in conventional linear B-M method is modified to sinusoidal phase modulation. The proposed sinusoidal B-M method relaxes the requirements on the phase-shifting mechanical system and avoids sensitivity fall-off along the transverse direction in contrast to the linear B-M method. A criterion for the relation between ...

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    10. Two-dimensional scanning realized by an asymmetry fiber cantilever driven by single piezo bender actuator for optical coherence tomography

      Two-dimensional scanning realized by an asymmetry fiber cantilever driven by single piezo bender actuator for optical coherence tomography

      We develop a fiber based probe that is capable of two-dimensional scanning applicable in optical coherence tomography (OCT). Based on the resonance of the fiber cantilever with asymmetry structure which has two distinguished resonant frequencies in orthogonal directions, Lissajous pattern is produced suitable for two-dimensional scanning upon a sample. Orthogonal resonances of the fiber cantilever are simultaneously excited by single piezo bender actuator with one driving signal consisting of two components corresponding to above-mentioned two resonant frequencies. By integrating a backward-placed two-dimensional position sensitive detector (PSD) into the probe, real-time lateral position of the scanning pattern is registered simultaneously for ...

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    11. Development of a non-uniform discrete Fourier transform based high speed spectral domain optical coherence tomography system

      Development of a non-uniform discrete Fourier transform based high speed spectral domain optical coherence tomography system

      We develop a high speed spectral domain optical coherence tomography (SD-OCT) system based on a custom-built spectrometer and non-uniform discrete Fourier transform (NDFT) to realize minimized depth dependent sensitivity fall-off. After precise spectral calibration of the spectrometer, NDFT of the acquired spectral data is adopted for image reconstruction. The spectrometer is able to measure a wavelength range of about 138nm with a spectral resolution of 0.0674nm at central wavelength of 835nm, corresponding to an axial imaging range of 2.56mm in air. Zemax simulations and sensitivity fall-off measurements under two alignment states of the spectrometer are given. Both theoretical ...

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    12. Common path endoscopic optical coherence tomography with outside path length compensation

      Endoscopic optical coherence tomography (OCT) allowing high-resolution imaging of internal tissue is attractive for medical imaging. Fibre, fibre bundle or GRIN lens rod acting as endoscopic probe is placed in the sample arm of a Michelson interferometer in current endoscopic OCT systems, this arrangement has to be carefully configured to avoid dispersion and polarization fading. In this study, a common path OCT system with outside path length compensation is presented. The system based on Fizeau configuration requires a Michelson interferometer to compensate the optical path difference between the reference and signal light in the Fizeau sensing interferometer. Experiments of path ...

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    1-12 of 12
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    1. (8 articles) Zhejiang University
    2. (1 articles) South China Normal University
    3. (1 articles) Capital Medical University
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    Development of a non-uniform discrete Fourier transform based high speed spectral domain optical coherence tomography system Two-dimensional scanning realized by an asymmetry fiber cantilever driven by single piezo bender actuator for optical coherence tomography Sinusoidal B-M method based spectral domain optical coherence tomography for the elimination of complex-conjugate artifact Deconvolution with fall-off compensated axial point spread function in spectral domain optical coherence tomography Spectral phase based k-domain interpolation for uniform sampling in swept-source optical coherence tomography Full-range swept source optical coherence tomography based on carrier frequency by transmissive dispersive optical delay line Wavelength-swept fiber laser based on acousto-optic tuning method Trojan-Horse Diameter-Reducible Nanotheranostics for Macroscopic/Microscopic Imaging-Monitored Chemo-Antiangiogenic Therapy Thickness of retinal pigment epithelium–Bruch’s membrane complex in adult Chinese using optical coherence tomography Interocular symmetry of optical coherence tomography parameters in healthy children and adolescents Fluorescein Leakage and Optical Coherence Tomography Angiography Features of Microaneurysms in Diabetic Retinopathy Cross-free in both lateral and axial directions Fourier-domain full-field optical coherence tomography