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Proceedings Paper

Laser scanner for thickness measurements on the production line
Author(s): Thomas C.Y. Leung; Rong-shing Shu; Jiunn-Shyong Wu
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Paper Abstract

In the manufacturing of continuously formed products such as metal plates and plastic sheets, on-line monitoring of thickness is important for quality control. Most cases require noncontact measurements. The most widely used optical technique is "optical triangulation" in which a lateral effect position-sensing detector is used. However, the technique has a limited measurement range to resolution ratio making it not suitable for some on-line applications. In this paper we propose a new approach to measure thickness in which the position of a scanning laser beam is timed. It eliminates the restriction of measurement range by the dimension of the detector as in traditional optical triangulation. Also, because small area silicon photodiodes are used, signal-to-noise ratio is largely enhanced thus improving the resolution. The probe we built demonstrates a 47 % measurement range-to-standoff distance ratio and a 2.8x104 measurement range-to-resolution ratio. Also, its performance is not influenced by large changes in object reflectivity.

Paper Details

Date Published: 1 August 1990
PDF: 8 pages
Proc. SPIE 1265, Industrial Inspection II, (1 August 1990); doi: 10.1117/12.20239
Show Author Affiliations
Thomas C.Y. Leung, National Central Univ. (Taiwan)
Rong-shing Shu, National Central Univ. (Taiwan)
Jiunn-Shyong Wu, National Central Univ. (Taiwan)

Published in SPIE Proceedings Vol. 1265:
Industrial Inspection II
Donald W. Braggins, Editor(s)

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