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Proceedings Paper

Conoscopic polarized interference applied in measuring uniaxial axis direction of electro-optic crystal
Author(s): Yong Liu; Hongzhen Jiang; Lin Zhang; Dong Li; Xu Liu; Fanglan Zheng
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Paper Abstract

The crystal can be used to be electro-optic switch because of its electro-optic modulation. Generally the uniaxial axis of electro-optic crystal is perpendicular to the light injection surface. Due to the manufacturing precision, the uniaxial axis direction has a little angle with the normal of the light injection surface, which affects the electro-optic modulation ability. In conoscopic polarized inference, due to birefraction the ordinary ray and extraordinary ray from crystal interferes after the polarizer. The interference pattern of crystal component is circle fringes with dark cross. The center of interference pattern has relation to the uniaxial axis direction. Using digital camera to capture the pattern and the center position of interferogram can be determinate by image processing program. In repeatability experiments the rms of center position is around 1 pixel. To measure the uniaxial axis direction, the normal direction of the crystal component should also be accurately determinate. Michelson interference method is introduced to determinate the normal direction. If rotate the crystal component around the normal direction in conoscopic polarized interference, the track of interferogram center is a circle theoretically. The circle center is related to the normal direction of crystal component, and the radii is related to the angle uniaxial axis, which can be determinate by least square fitting method. Experiment result shows that the measuring precision can achieves several tens of microradians.

Paper Details

Date Published: 19 October 2016
PDF: 4 pages
Proc. SPIE 10155, Optical Measurement Technology and Instrumentation, 1015521 (19 October 2016); doi: 10.1117/12.2246791
Show Author Affiliations
Yong Liu, China Academy of Engineering Physics (China)
Hongzhen Jiang, China Academy of Engineering Physics (China)
Lin Zhang, China Academy of Engineering Physics (China)
Dong Li, China Academy of Engineering Physics (China)
Xu Liu, China Academy of Engineering Physics (China)
Fanglan Zheng, China Academy of Engineering Physics (China)

Published in SPIE Proceedings Vol. 10155:
Optical Measurement Technology and Instrumentation
Sen Han; JiuBin Tan, Editor(s)

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