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Proceedings Paper

Optical heterodyne surface profiling interferometer with automatic focusing
Author(s): Hongzhi Zhao; Rong Liang; Yongjun Wu; Dacheng Li; Mang Cao
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Paper Abstract

In modern semiconductor and optics industries, there is a strong demand for a highly sensitive and non-contact surface profilometer. This paper describes an optical heterodyne surface profiling interferometer with automatic focusing which has been developed recently. The essential feature of the profilometer is a newly designed common-path method to minimize the effects of environmental conditions. A powerful signal processing scheme is also developed, which includes three parts: automatic voltage control, phase measurement and automatic focusing control. All these make the repeatability and stability of the profiling interferometer greatly improved. The height resolution is 3.5 nm and lateral resolution is 0.4 micrometers . Experiments show that the profiling interferometer is suitable for on-line use.

Paper Details

Date Published: 18 August 1997
PDF: 5 pages
Proc. SPIE 3185, Automatic Inspection and Novel Instrumentation, (18 August 1997); doi: 10.1117/12.284032
Show Author Affiliations
Hongzhi Zhao, Tsinghua Univ. (China)
Rong Liang, Tsinghua Univ. (China)
Yongjun Wu, National Univ. of Singapore (Singapore)
Dacheng Li, Tsinghua Univ. (China)
Mang Cao, Tsinghua Univ. (China)


Published in SPIE Proceedings Vol. 3185:
Automatic Inspection and Novel Instrumentation
Anthony Tung Shuen Ho; Sreenivas Rao; Lee Ming Cheng, Editor(s)

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