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🏛️國立陽明交通大學機構典藏

Author: search.filters.author.Chen, Jing-HengSubject: search.filters.subject.Talbot effect

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Now showing 1 - 4 of 4
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    Stress measurement of thin film on flexible substrate by using projection moire method and heterodyne interferometry
    (2016-06-01)
    Chen, Kun-Huang
    ;
    Chen, Jing-Heng
    ;
    Tseng, Hua-Ken
    ;
    Chang, Wei-Yao
    ;
    光電工程學系
    We propose a stress measurement system based on a projection moire method and heterodyne interferometry for thin films on a flexible substrate. In the measurement setup, a CMOS camera in which every pixel can receive a series of heterodyne moire signals by using a continuously relative displacement with a constant velocity is used. Furthermore, the phase of the optimized sinusoidal curve and the surface profile of the flexible substrate are determined using a least-squares sine fitting algorithm. The thin-film stress is obtained by representing the cross-sectional curve of the surface profile by using a polynomial fitting method, estimating the resultant curvature radii of the uncoated and coated substrates, and using these two radii in the corrected Stoney formula. The proposed measurement system has the advantages of high accuracy, high resolution, and high capacity for substrates with high flexibility and a large measurement depth. (C) The Authors.
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    Collimation testing and calibration using a heterodyne Moire method
    (2014-11-01)
    Chang, Wei-Yao
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    Hsu, Ken Y.
    ;
    Chen, Kun-Huang
    ;
    Chen, Jing-Heng
    ;
    光電工程學系
    This study proposes a simple, rapid, and highly accurate method to achieve the collimation testing and calibration of laser light beams. By applying a relative constant velocity to two gratings, every pixel of a CMOS camera can receive a series of heterodyne moire signals. Based on the least squares sine fitting algorithm, the phase of the optimized sinusoidal wave can be obtained. Consequently, the phase slope along the direction perpendicular to the grating lines can be estimated and then used to judge the degree of collimation. Furthermore, by measuring only two phase slopes at two positions of the collimating lens, the calibration of the light beam collimation can also be achieved. The experiment validated the proposed method, and the positioning error of the light beam collimation was approximately 7 mu m. (C) 2014 Elsevier Ltd. All rights reserved.
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    Corneal surface reconstruction by using heterodyne moire method
    (2013)
    Chang, Wei-Yao
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    Chen, Kun-Huang
    ;
    Chen, Der-Chin
    ;
    Tseng, Jung-Kai
    ;
    Chen, Shyan-Tarng
    In this paper, we propose a simple method for reconstructing the corneal surface profile by using the Talbot effect, projection moire method, and heterodyne interferometry. A linear grating is obliquely illuminated by an expanding collimated light, and a self-image of this grating can be generated and projected on the corneal surface. The deformed grating fringes are imaged on the second grating to form the moire fringes. If the first grating is moved with a constant velocity along the grating plane, a series of sampling points of the sinusoidal wave which behave like the heterodyne interferometric signal can be recorded by a CMOS camera. The phase distribution of the corneal surface then can be obtained with the IEEE 1241 least-square sine fitting algorithm and 2D phase unwrapping. Finally, the corneal surface profile can be reconstructed by substituting the phase distribution into special derived equation. This method provides the advantages of a simple optical setup, ease of operation, high stability, and high resolution.
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    Heterodyne moire interferometry for measuring corneal surface profile
    (2014-03-01)
    Chang, Wei-Yao
    ;
    Chen, Kun-Huang
    ;
    Chen, Der-Chin
    ;
    Tseng, Jung-Kai
    ;
    Chen, Shyan-Tarng
    This study proposes an accurate method for reconstructing the corneal surface profile. By applying a constant velocity to the projection grating along the grating plane, a series of sampling points of the sinusoidal wave, which behaves in the manner of heterodyne interferometric signals, can be recorded using a CMOS camera. The phase distribution of the moire fringes can then be obtained using the IEEE 1241 least-square sine fitting algorithm and two-dimensional (2D) phase unwrapping. Finally, the corneal surface profile can be reconstructed by substituting the phase distribution into a specially derived equation. To validate the proposed method, the corneal surface of a pig eyeball was measured. The measurement resolution was approximately 3.5 mu m. Because of the introduction of the Talbot effect, the projection moire method, and heterodyne interferometry, this approach provides the advantages of a simple optical setup, ease of operation, high stability, and high resolution. (C) 2013 Elsevier Ltd. All rights reserved.