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Proceedings Paper

Practical heterodyne surface profiling interferometer with automatic focusing
Author(s): Hongzhi Zhao; Rong Liang; 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 for on-line non-contact measurement with automatic focusing which has been developed recently. The essential feature of the profilometer is a newly designed common-path configuration to minimizes the effects caused by vibration, air turbulence and other environmental variations. A single-mode frequency-stabilized laser diode (780 nm) serves as the light source to make the whole system compact (total volume 250L x 200W x 100Dmm). 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 system has vertical resolution of 0.39 nm and lateral resolution of 0.73 micrometer. During approximate an hour, the stability is within 1.95 nm (3σ).

Paper Details

Date Published: 6 October 2000
PDF: 6 pages
Proc. SPIE 4231, Advanced Optical Manufacturing and Testing Technology 2000, (6 October 2000); doi: 10.1117/12.402820
Show Author Affiliations
Hongzhi Zhao, Tsinghua Univ. (United States)
Rong Liang, Tsinghua Univ. (China)
Dacheng Li, Tsinghua Univ. (China)
Mang Cao, Tsinghua Univ. (China)

Published in SPIE Proceedings Vol. 4231:
Advanced Optical Manufacturing and Testing Technology 2000
Li Yang; Harvey M. Pollicove; Qiming Xin; James C. Wyant, Editor(s)

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