A Laser Heterodyne Interferometer For Measuring Surface Roughness

Wang Jia; Gu Lirong; Zhang Enyao; Cao Mang; Li Dacheng

doi:10.1117/12.961760

11 October 1989 A Laser Heterodyne Interferometer For Measuring Surface Roughness

Wang Jia, Gu Lirong, Zhang Enyao, Cao Mang, Li Dacheng

Proceedings Volume 1138, Optical Microlithography and Metrology for Microcircuit Fabrication; (1989) https://doi.org/10.1117/12.961760
Event: 1989 International Congress on Optical Science and Engineering, 1989, Paris, France

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.

Citation Download Citation

Wang Jia, Gu Lirong, Zhang Enyao, Cao Mang, and Li Dacheng "A Laser Heterodyne Interferometer For Measuring Surface Roughness", Proc. SPIE 1138, Optical Microlithography and Metrology for Microcircuit Fabrication, (11 October 1989); https://doi.org/10.1117/12.961760

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