Study on Glass Defect Inspection Based on Projecting Grating Method

    Volume 41, Issue 2 (March 2013)

    ISSN: 0090-3973

    CODEN: JTEOAD

    Published Online: 22 January 2013

    Page Count: 8


    Jin, Yong
    National Key Lab for Electronic Measurement Technology, North Univ. of China, Taiyuan,

    Wang, Zhaoba
    National Key Lab for Electronic Measurement Technology, North Univ. of China, Taiyuan,

    Zhu, Linquan
    National Key Lab for Electronic Measurement Technology, North Univ. of China, Taiyuan,

    Yang, Jiliang
    National Key Lab for Electronic Measurement Technology, North Univ. of China, Taiyuan,

    Wei, Bo
    National Key Lab for Electronic Measurement Technology, North Univ. of China, Taiyuan,

    (Received 27 January 2012; accepted 31 July 2012)

    Abstract

    An inspection method based on transmission-mode projecting grating for glass defects has been proposed and verified by experiments. Sinusoidal fringe on the glass is collected using a linear CCD. The fringe curve can be corrected through the Fourier series fitting method to eliminate the constant non-uniformity of the light intensity of a light-emitting diode. The one-dimensional Fourier transform is applied to the corrected fringe curve; the Gaussian band-reject filter is designed to attenuate the first-order spectrum, and a Gaussian band-pass filter having the opposite characteristic attenuates other frequencies (except those in the first-order spectrum). In this way, the defect image and the phase map are obtained. A double threshold segmentation algorithm is applied to get a ternary-value image of the defects, with judgment of the defects’ size and position based on the connected region. Based on the phase map, a calculation method of diopters is proposed. A method for defect type judgment is raised. The results show that the resolution of the real-time testing can reach 0.1 mm × 0.1 mm.


    Paper ID: JTE20120008

    DOI: 10.1520/JTE20120008

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    Author
    Title Study on Glass Defect Inspection Based on Projecting Grating Method
    Symposium , 0000-00-00
    Committee C14