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Optical Engineering

Development of optical noncontact sensor for measurement of three-dimensional profiles using depolarized components of scattered light
Author(s): Kanji Mashimo; Tetsuya Nakamura; Yoshihisa Tanimura
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Paper Abstract

A new optical noncontact sensor is proposed for measuring profiles of an object with 3-D free-form surfaces. The sensor consists of both low-resolution and high-resolution optical systems. Two linearly polarized laser beams from the sensor are focused on the object surface to be measured. Some of the depolarized components of light scattered from the object surface, i.e., the polarized components orthogonal to those of the incident beams, are detected to exclude specularly reflected light. The triangulation method is applied to the low-resolution optical system, which can be used to detect a wide range of height. The astigmatic focus error method is applied to the high-resolution optical system to detect the focused positioning signal of the object surface more precisely than with the low-resolution system. Using a measuring instrument fabricated with the new optical noncontact sensor, 3-D profiles of diffuse reflection surfaces and metal surfaces on which both specular reflection and diffuse reflection occur can be measured. Adverse effects of surface roughness, scratches, and diffraction on measurements can be reduced.

Paper Details

Date Published: 1 January 1997
PDF: 8 pages
Opt. Eng. 36(1) doi: 10.1117/1.601164
Published in: Optical Engineering Volume 36, Issue 1
Show Author Affiliations
Kanji Mashimo, Gunma Prefectural Industrial Technology Research Lab. (Japan)
Tetsuya Nakamura, Gunma Prefectural Industrial Technology Research Lab. (Japan)
Yoshihisa Tanimura, National Research Lab. of Metrology (Japan)


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