1. Articles from Feng-Yu Chang

    1-11 of 11
    1. Optical coherence tomography-guided laser microsurgery for blood coagulation with continuous-wave laser diode

      Optical coherence tomography-guided laser microsurgery for blood coagulation with continuous-wave laser diode

      Blood coagulation is the clotting and subsequent dissolution of the clot following repair to the damaged tissue. However, inducing blood coagulation is difficult for some patients with homeostasis dysfunction or during surgery. In this study, we proposed a method to develop an integrated system that combines optical coherence tomography (OCT) and laser microsurgery for blood coagulation. Also, an algorithm for positioning of the treatment location from OCT images was developed. With OCT scanning, 2D/3D OCT images and angiography of tissue can be obtained simultaneously, enabling to noninvasively reconstruct the morphological and microvascular structures for real-time monitoring of changes in ...

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    2. Optical inspection of solar cells using phase-sensitive optical coherence tomography

      Optical inspection of solar cells using phase-sensitive optical coherence tomography

      The inspection and measurement of solar cells has become an important technique in evaluating the efficiency and quality of solar cell devices. Currently, surface defect detection of solar cells can be achieved by several approaches such as machine vision, photoluminescence, and electroluminescence imaging techniques. Nevertheless, it is still difficult to inspect the inner structures of solar cells. In response to this need, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have become common techniques for investigating the nanostructures of solar cells. However, both carry the disadvantages of destructive imaging, high cost, and a small inspection area. Moreover, it is ...

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    3. Investigation of temporal vascular effects induced by focused ultrasound treatment with speckle-variance optical coherence tomography

      Investigation of temporal vascular effects induced by focused ultrasound treatment with speckle-variance optical coherence tomography

      Focused ultrasound (FUS) can be used to locally and temporally enhance vascular permeability, improving the efficiency of drug delivery from the blood vessels into the surrounding tissue. However, it is difficult to evaluate in real time the effect induced by FUS and to noninvasively observe the permeability enhancement. In this study, speckle-variance optical coherence tomography (SVOCT) was implemented for the investigation of temporal effects on vessels induced by FUS treatment. With OCT scanning, the dynamic change in vessels during FUS exposure can be observed and studied. Moreover, the vascular effects induced by FUS treatment with and without the presence of ...

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    4. Feature Of The Week 11/17/13: Monitoring of wound healing process of human skin after fractional laser treatments with optical coherence tomography

      Feature Of The Week 11/17/13: Monitoring of wound healing process of human skin after fractional laser treatments with optical coherence tomography

      Fractional photothermolysis induced by non-ablative fractional lasers (NAFLs) or ablative fractional lasers (AFLs) can remodel the skin, regenerate collagen, and remove tumor tissue. However, fractional laser treatments may result in severe side effects, and multiple treatments are required to achieve the expected outcome. Thus, the treatment outcome and downtime after fractional laser treatments are key issues to determine the following treatment strategy. In this study, an optical coherence tomography (OCT) system was implemented for in vivo studies of wound healing after NAFL and AFL treatments. According to the OCT scanning results, the laser-induced photothermolysis including volatilization and coagulation could be ...

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    5. Monitoring of wound healing process of human skin after fractional laser treatments with optical coherence tomography

      Monitoring of wound healing process of human skin after fractional laser treatments with optical coherence tomography

      Fractional photothermolysis induced by non-ablative fractional lasers (NAFLs) or ablative fractional lasers (AFLs) can remodel the skin, regenerate collagen, and remove tumor tissue. However, fractional laser treatments may result in severe side effects, and multiple treatments are required to achieve the expected outcome. Thus, the treatment outcome and downtime after fractional laser treatments are key issues to determine the following treatment strategy. In this study, an optical coherence tomography (OCT) system was implemented for in vivo studies of wound healing after NAFL and AFL treatments. According to the OCT scanning results, the laser-induced photothermolysis including volatilization and coagulation could be ...

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    6. Evaluation of Moisture-Related Attenuation Coefficient and Water Diffusion Velocity in Human Skin Using Optical Coherence Tomography

      Evaluation of Moisture-Related Attenuation Coefficient and Water Diffusion Velocity in Human Skin Using Optical Coherence Tomography

      In this study, time-resolved optical coherence tomography (OCT) scanning images of the process of water diffusion in the skin that illustrate the enhancement in the backscattered intensities due to the increased water concentration are presented. In our experiments, the water concentration in the skin was increased by soaking the hand in water, and the same region of the skin was scanned and measured with the OCT system and a commercial moisture monitor every three minutes. To quantitatively analyze the moisture-related optical properties and the velocity of water diffusion in human skin, the attenuation coefficients of the skin, including the epidermis ...

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    7. Noninvasive imaging of heart chamber in Drosophila with dual-beam optical coherence tomography

      Noninvasive imaging of heart chamber in Drosophila with dual-beam optical coherence tomography

      The heart chamber of an adult Drosophila is approximately 2 mm long and 0.5 mm wide, and the interwall separation of different heart portions during systole and diastole range from tens of micrometers to hundreds of micrometers. Furthermore, the heart chamber has a curved structure, which results in the larger differences in depth between the different heart portions. However, applying the wavelength calibration process before Fourier transform in an optical coherence tomography (OCT) system may cause degradation in system sensitivity and longitudinal resolution when the optical path difference between the reference and sample arms increases, which makes imaging the ...

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    8. Quantitative Phase Imaging With Swept-Source Optical Coherence Tomography for Optical Measurement of Nanostructures

      Quantitative Phase Imaging With Swept-Source Optical Coherence Tomography for Optical Measurement of Nanostructures

      In this letter, a phase-sensitive, swept-source optical coherence tomography (SS-OCT) system is implemented for the optical measurement of nanostructures. A new approach is proposed to reduce the phase errors, resulting from trigger jitter of the swept source and the asynchronization between the A-scan trigger and OCT signal at the data acquisition end, with a narrowband fiber Bragg grating to generate the accurate A-scan trigger. Furthermore, combining the common-path configuration with the proposed approach, the displacement sensitivity can be calculated to be 80 pm when the swept source is operated at 30 kHz. Finally, the conducting glass was scanned with the ...

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    9. Microvascular Imaging Using Swept-Source Optical Coherence Tomography with Single-Channel Acquisition

      Microvascular Imaging Using Swept-Source Optical Coherence Tomography with Single-Channel Acquisition
      This study proposes a new approach to improve the phase stability for swept-source optical coherence tomography (SS-OCT) with single-channel acquisition. This approach can improve the phase instability due to the A-scan trigger jitter from the swept source, or the asynchronization between the A-scan trigger and high-speed digitizer, which enables the visualization of vascular structures by SS-OCT. Aside from reducing the phase noise of the OCT system, only one channel is required for the A-scan trigger, data storage, and wavelength calibration by implementing the proposed approach. Finally, human skin was scanned in vivo to demonstrate the vascular images.
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    10. Observations of cardiac beating behaviors of wild-type and mutant Drosophilae with optical coherence tomography

      Observations of cardiac beating behaviors of wild-type and mutant Drosophilae with optical coherence tomography
      Time-resolved optical coherence tomography (OCT) scanning images of wild-type and mutant fruit flies (Drosophila melanogaster), illustrating the heartbeat patterns for evaluating their cardiac functions, are demonstrated. Based on the heartbeat patterns, the beat rate and the relative phase between the first two heart segments can be evaluated. The OCT scanning results of mutant flies with impaired proteasome function in cardiac muscles show irregular heartbeat patterns and systematically decreased average beat rates, when compared with the regular patterns of ∼4.97 beats/s in average beat rate of the wild-type. In both wild-type and proteasome mutant flies, the beatings at different ...
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    11. Defect detection and property evaluation of indium tin oxide conducting glass using optical coherence tomography

      Defect detection and property evaluation of indium tin oxide conducting glass using optical coherence tomography
      This study demonstrates a new approach for evaluating the properties of indium tin oxide (ITO) conducting glass and identifying defects using optical coherence tomography (OCT). A swept-source OCT system was implemented to scan the ITO conducting glass to enable two-dimensional or three-dimensional imaging. With OCT scanning, the defects can be clearly identified at various depths. Several parameters in addition to morphological information can be estimated simultaneously, including the thickness of the glass substrate, the refractive index, reflection coefficient, and transmission coefficient, all of which can be used to evaluate the quality of ITO conducting glass. This study developed a modified ...
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    1-11 of 11
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    1. (11 articles) Chang Gung University
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    Defect detection and property evaluation of indium tin oxide conducting glass using optical coherence tomography Observations of cardiac beating behaviors of wild-type and mutant Drosophilae with optical coherence tomography Microvascular Imaging Using Swept-Source Optical Coherence Tomography with Single-Channel Acquisition Quantitative Phase Imaging With Swept-Source Optical Coherence Tomography for Optical Measurement of Nanostructures Noninvasive imaging of heart chamber in Drosophila with dual-beam optical coherence tomography Evaluation of Moisture-Related Attenuation Coefficient and Water Diffusion Velocity in Human Skin Using Optical Coherence Tomography Monitoring of wound healing process of human skin after fractional laser treatments with optical coherence tomography Feature Of The Week 11/17/13: Monitoring of wound healing process of human skin after fractional laser treatments with optical coherence tomography Investigation of temporal vascular effects induced by focused ultrasound treatment with speckle-variance optical coherence tomography Optical inspection of solar cells using phase-sensitive optical coherence tomography Post-Doctoral and Graduate Student Research Positions at the University of Illinois Urbana-Champaign Multiscale correlation of microvascular changes on optical coherence tomography angiography with retinal sensitivity in diabetic retinopathy