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Proceedings Paper

Displacement measurement with λ/8 resolution based on the bifurcate subcavity modulation effect in a dual frequency laser
Author(s): Weixin Liu; Shulian Zhang
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Paper Abstract

A novel method for displacement measuring is proposed based on the bifurcate subcavity modulation effect in a dual frequency laser. Owing to the intracavity wave plate, the laser operates on two orthogonally polarized modes. If a portion of laser, channeled into a subcavity by the wave plated, is reinjected back to the resonator, the mode intensities are modulated with a period of a half of wavelength, respectively. And the two modulations behave a 90 degree phase difference, which could subdivide a period into four regions: horizontal polarization, two polarizations, vertical polarization, and no light. In this paper, this subcavity modulation effect is demonstrated experimentally and theoretically. Furthermore, a displacement measurement of the subcavity mirror is developed with resolution up to λ/8, viz. about 79nm at laser wavelength of 632.8nm. The direction discrimination of measuring could also be realized utilizing the sequence of four different subdivision zones. The measuring range, mainly limited by both the splitting frequency difference and the bifurcate subcavity length, could reach tens of millimeters. Measurement results are presented and the corresponding error analyses are discussed. This system has great potential in applying to metrological fields for its simplicity, compactness and high quality performance.

Paper Details

Date Published: 3 February 2009
PDF: 8 pages
Proc. SPIE 7160, 2008 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Applications, 716015 (3 February 2009); doi: 10.1117/12.807157
Show Author Affiliations
Weixin Liu, Tsinghua Univ. (China)
Shulian Zhang, Tsinghua Univ. (China)


Published in SPIE Proceedings Vol. 7160:
2008 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Applications

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