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Proceedings Paper

Surface profile measurement of a diffraction grating by a laser beam scanning interferometer using sinusoidal phase modulation
Author(s): Osami Sasaki; Takuya Kubota; Samuel Choi; Takamasa Suzuki
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Paper Abstract

It is difficult in interferometric metrology to maintain high spatial resolution over a large measurement region. In this paper this characteristic is achieved by scanning two focused laser beams of about 6 microns diameter over an object surface and a reference mirror surface, respectively, with a rotating mirror, a lens, and a polarization beam splitter. An electric-optic phase modulator generates the phase difference of a sinusoidal waveform of 10 MHz between the two focused beams to calculate the phase of the interference signal. Because the beam focused onto a diffraction grating of 50 microns period is not diffracted strongly, a surface profile of the grating can be exactly measured by this interferometer over the measurement region of 16 mm with the spatial resolution of 2 microns.

Paper Details

Date Published: 6 September 2013
PDF: 7 pages
Proc. SPIE 8839, Dimensional Optical Metrology and Inspection for Practical Applications II, 883906 (6 September 2013); doi: 10.1117/12.2025328
Show Author Affiliations
Osami Sasaki, Niigata Univ. (Japan)
Takuya Kubota, Niigata Univ. (Japan)
Samuel Choi, Niigata Univ. (Japan)
Takamasa Suzuki, Niigata Univ. (Japan)

Published in SPIE Proceedings Vol. 8839:
Dimensional Optical Metrology and Inspection for Practical Applications II
Kevin G. Harding; Peisen S. Huang; Toru Yoshizawa, Editor(s)

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