1. Articles from Qiukun Zhang

    1-7 of 7
    1. Anti-noise frequency estimation performance of Hanning-windowed energy centrobaric method for optical coherence velocimeter

      Anti-noise frequency estimation performance of Hanning-windowed energy centrobaric method for optical coherence velocimeter

      The Optical Coherence Velocimeter (OCV) technology is a technique for high-precision displacement and vibration measurement based on the principle of spectral domain optical coherence method. The key of this technology is to realize nanometer or even sub-nanometer measurement by high precision frequency estimation method called as Hanning-window energy centrobaric method (HnWECM). This paper analyses the error transmission process of HnWECM, and proposes a calculation method based on Paserval's theorem to establishes the accuracy theory of HnWECM. It shows that the variance of the estimated frequency using HnWECM is only proportional to the signal-to-noise ratio (SNR) and very close to ...

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    2. Optical coherent tomography to evaluate the degree of inflammation in a mouse model of colitis

      Optical coherent tomography to evaluate the degree of inflammation in a mouse model of colitis

      Background: There is an urgent need to develop a noninvasive imaging technique for the diagnosis of early inflammatory lesions or early and real-time microscopic assessment before selecting the most representative biopsy sites. Methods: In this study, a dextran sulfate sodium colitis model was developed, and intestinal histological damage scores measured the degree of inflammation in colitis. According to these scores, 6 parameters were designed for hematoxylin and eosin (HE) sections based on morphological changes, and 2 parameters were designed for optical coherence tomography (OCT) images to measure submucosal edema by morphological changes to evaluate inflammation degrees in the colon. Spearman ...

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    3. Full range line-field optical coherence tomography for high-accuracy measurements of optical lens

      Full range line-field optical coherence tomography for high-accuracy measurements of optical lens

      A full range line-field Fourier domain optical coherence tomography system (LF-FDOCT) with an accuracy at nanoscale was proposed for high-accuracy measurements of optical lens surface profile. The line-field surface curve information of optical lens could be obtained in one measurement which does not need point-by-point scanning used in traditional one-dimensional FDOCT system. The measurement accuracy of surface profile curve could be improved from micrometer scale to nanoscale by applying spectral centre correction method (SCCM) to the complex spectral interferogram. The corrected five phase shifting (CFPS) method was employed to eliminate the complexconjugate artifacts and the polychromatic error. Numerical simulation and ...

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    4. High-performance optical coherence velocimeter: theory and applications

      High-performance optical coherence velocimeter: theory and applications

      We proposed a high-performance optical coherence velocimeter (OCV) based on broadband optical interference which achieves spatial resolution from interference cancellation or enhancement of different components of the broadband light. There is a challengeable issue for OCV that the interference fringes become blurred when the velocity of detected object is relatively large, hindering the pace of OCV application in high-velocity field. To resolve this, the relationship between blurry coefficient and OCV system parameters (e.g., exposure time, central wavelength, bandwidth of source) was derived. It was found that blurry coefficient changed with oscillatory decay form and reached the minimum at each ...

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    5. Five-Frame Variable Phase-Shifting Method for Full-Range Spectral-Domain Optical Coherence Tomography

      Five-Frame Variable Phase-Shifting Method for Full-Range Spectral-Domain Optical Coherence Tomography

      In order to achieve a better complex conjugate artifacts (CCA) suppression, we propose a five-frame variable phase-shifting (FVP) method for spectral domain optical coherence tomography (SD-OCT). The traditional five-frame invariant phase-shifting (FIP) method employs five phase shifts correlate with the center wavelength. However, due to the effects of polychromatic errors, the FIP method cannot get excellent CCA suppression. In the present work, we employ FVP method using variable phase shifts which is dependent on all the wavelengths and therefore, theoretically, the system would have no effects of polychromatic errors. This is the reason why the FVP method would achieve better ...

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    6. Enhanced Optical Coherence Vibration Tomography for Subnanoscale-Displacement-Resolution Calibration of Piezoelectric Actuators

      Enhanced Optical Coherence Vibration Tomography for Subnanoscale-Displacement-Resolution Calibration of Piezoelectric Actuators

      We report a sub nanoscale-displacement-resolution optical coherence vibration tomography (SOCVT) system for real-time calibration of piezoelectric actuators. The calibrations of the actuators at nanoscale or microscale displacement ranges were performed by varying the input voltage over the entire range in the ascending and descending directions. The computational and experimental results demonstrated that the developed SOCVT could be used to characterizethe dynamic hysteretic behaviour, nonlinear effect, and impulsive behaviour of piezoelectric actuators. The SOCVT technique is non-contact and non-invasive in nature, making it ideal for real-time and in situ ultra-precision calibration of piezoelectric actuators, which are widely used in active vibration ...

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    7. Two-dimensional optical coherence tomography for real-time structural dynamical characterization

      Two-dimensional optical coherence tomography for real-time structural dynamical characterization

      We present a two-dimensional optical coherence vibration tomography (2DOCVT) system with an ultra-precision displacement resolution of ~0.1 nm that is capable of in site real-time absolute displacement measurement of structural line vibrations. Experimental results of sinusoidal, sweep and impulse vibrations were reported. The key figures of merit such as the 2DOCVT system could obtain fast line vibration measurement without scanning and it also could be used to capture structural modal parameters in one single impulse excitation measurement without any vibration excitation input information, making it attractive for the application in low-frequency vibration measurement and response-only modal analysis.

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    1-7 of 7
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    1. (1 articles) Fujian Normal University
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