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Proceedings Paper

Application of the astigmatic method to the thickness measurement of glass substrates
Author(s): Jingchao Zhang; Rui Ding; Xi Yan
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Paper Abstract

We developed a high accuracy thickness measurement system for glass substrates based on the optical design of the astigmatic method. Reflective optical measurement systems are the most widely used glass thickness measurement methods in current industrial production practice. The incline of glass in reflective optical measurement system is the main factor of inaccuracy of thickness data. Compared with reflective optical measurement system, we found our design could effectively eliminate errors of glass thickness caused by slightly shifts of glass tilt. The astigmatic optical system includes a laser diode, a cylindrical lens, and a quadrant detector. This method measures the astigmatic focusing error signal induced form the measured glass placed in the astigmatic optical system. The astigmatic focusing error signal is converted into the thickness of the glass substrate. The proposed glass thickness measurement system is verified by using a coordinate measuring machine (CMM). On the validation of our system using tri-ordinate measuring machine, the accuracy of the proposed system is 0.2 μm, with a standard deviation of 0.7μm within the thickness measuring range of 1.2mm.

Paper Details

Date Published: 22 August 2011
PDF: 8 pages
Proc. SPIE 8192, International Symposium on Photoelectronic Detection and Imaging 2011: Laser Sensing and Imaging; and Biological and Medical Applications of Photonics Sensing and Imaging, 819245 (22 August 2011); doi: 10.1117/12.901221
Show Author Affiliations
Jingchao Zhang, Yanshan Univ. (China)
Rui Ding, Yanshan Univ. (China)
Xi Yan, Yanshan Univ. (China)


Published in SPIE Proceedings Vol. 8192:
International Symposium on Photoelectronic Detection and Imaging 2011: Laser Sensing and Imaging; and Biological and Medical Applications of Photonics Sensing and Imaging
Farzin Amzajerdian; Weibiao Chen; Chunqing Gao; Tianyu Xie, Editor(s)

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