20 November 2009 A single channel spatial polarization encoding and decoding method based on photoelastic modulator
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A method to encode and decode the spatial position using polarization is proposed. Birefringent wedge and photoelastic modulator (PEM) are used to encode and modulate the laser with a polarizer and an analyzer. The state of polarization (SOP) of laser beam changes gradually along the gradient direction of birefringent wedge. The spatial polarization encoding beam is transmitted by a beam expander to form a spatial encoding field. A part of laser carrying the information of spatial position in the field is received by detector. With signal processing, the harmonic terms of detected intensity are obtained to realize the single channel decoding. With the single channel spatial polarization encoding and decoding method, the problem of incorporating automatic gain control (AGC) between separate channel signals can be overcome and the precision of decoding is improved by its rotation-invariant feature, and the results of decoding vary linearly with retardation in the range of ±180°. In experiments, the relationship between decoding spatial position and the true value of position is linear. Usefulness of the method is verified.
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Jie Han, Jie Han, Aijun Zeng, Aijun Zeng, Chunxia Feng, Chunxia Feng, Guangchao Zhou, Guangchao Zhou, Huijie Huang, Huijie Huang, Hongbing Qian, Hongbing Qian, "A single channel spatial polarization encoding and decoding method based on photoelastic modulator", Proc. SPIE 7511, 2009 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Systems, 75110R (20 November 2009); doi: 10.1117/12.838050; https://doi.org/10.1117/12.838050

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