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Optical Engineering

Displacement sensors based on feedback effect of orthogonally polarized lights of frequency-split HeNe lasers
Author(s): Yingchun Ding; Shulian Zhang; Yan Li; Jun Zhu; Wenhua Du; Rui Suo
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Paper Abstract

The novel principle of laser feedback displacement sensors is presented and demonstrated. A birefringent dual-frequency laser is used as the light source, which outputs two polarization lights, o light and e light. The two polarization lights are divided by a Wollaston prism and detected separately by two photoelectric detectors. When the feedback mirror is moved along the laser axis, the intensities of both the o light and the e light change periodically. And an increase of o light intensity always accompanies a decrease of e light intensity. If a threshold intensity for the output light is appropriately given by the signal processing circuits, the remaining intensity curves in each period shows four different polarization states: e light, e light and o light, o light, and no light. Each change of polarization state corresponds to a λ/8 displacement of the feedback mirror. We judge the movement direction by the difference of the order of the polarization states that appear. The resolution of the system is 0.079 μm. The possibility of employing the fold feedback cavity is discussed, and its resolution is believed to reach 0.0395 μm.

Paper Details

Date Published: 1 August 2003
PDF: 4 pages
Opt. Eng. 42(8) doi: 10.1117/1.1588658
Published in: Optical Engineering Volume 42, Issue 8
Show Author Affiliations
Yingchun Ding, Tsinghua Univ. (China)
Shulian Zhang, Tsinghua Univ. (China)
Yan Li, Tsinghua Univ. (China)
Jun Zhu, Tsinghua Univ. (China)
Wenhua Du, Tsinghua Univ. (China)
Rui Suo, Tsinghua Univ. (China)

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