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Proceedings Paper

Algorithm for determining line centre with microscope measuring system
Author(s): Hengzheng Wei; Weinong Wang; Guoying Ren; Limei Pei
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Paper Abstract

A new method for determining line centre is proposed within a microscope imaging measurement system. Due to the optical diffraction effect the image of each line on the scale is stripe shaped. The strip can be molded as two edges that close together. With the gradient algorithm all the local maximum and minimum in the line scale image are detected. Therefore the rising and falling edge can be positioned in pixel level. The line centre is then the middle of between the rising and falling edge. To achieve a high level accuracy of the centre position, with the points near the line centre in the gradient image a least-squares line fitting algorithm is used. The zero gradient magnitude is located with sub-pixel resolution. Experiments have been performed with a standard line scale under different objectives. Results indicate the effectiveness of the method.

Paper Details

Date Published: 12 November 2010
PDF: 6 pages
Proc. SPIE 7855, Optical Metrology and Inspection for Industrial Applications, 785524 (12 November 2010); doi: 10.1117/12.871046
Show Author Affiliations
Hengzheng Wei, National Institute of Metrology (China)
Weinong Wang, National Institute of Metrology (China)
Guoying Ren, National Institute of Metrology (China)
Limei Pei, National Institute of Metrology (China)

Published in SPIE Proceedings Vol. 7855:
Optical Metrology and Inspection for Industrial Applications
Kevin Harding; Peisen S. Huang; Toru Yoshizawa, Editor(s)

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