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Proceedings Paper

A Laser Heterodyne Interferometer For Measuring Surface Roughness
Author(s): Wang Jia; Gu Lirong; Zhang Enyao; Cao Mang; Li Dacheng
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Paper Abstract

A laser heterodyne interferometer for measuring surface microtopography is described in this paper. A frequency difference between reference arm and measuring arm is obtained by utilizing two acousto-optic modulators in the interferometer. Phase demodulation technique is employed to improve the resolution up to 0.36 degrees, corresponding to one thousandth wavelength. Height variations of 10 nm can be resolved, while the theoretical height resolution is 10 angstroms. The simplest layout and the less optics are used in the interferometer without any polarizes and lens designed specially as other interferometers.

Paper Details

Date Published: 11 October 1989
PDF: 4 pages
Proc. SPIE 1138, Optical Microlithography and Metrology for Microcircuit Fabrication, (11 October 1989); doi: 10.1117/12.961760
Show Author Affiliations
Wang Jia, Tsinghua University (China)
Gu Lirong, Tsinghua University (China)
Zhang Enyao, Tsinghua University (China)
Cao Mang, Tsinghua University (China)
Li Dacheng, Tsinghua University (China)

Published in SPIE Proceedings Vol. 1138:
Optical Microlithography and Metrology for Microcircuit Fabrication
Michel J. Lacombat; Stefan Wittekoek, Editor(s)

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