| With the development of laser and remote sensing detection, people have pay a lot attention to the measurement of the polarization state of light beam especially to the accurate measurement.The state of polarization of the emitted light in general provides information which can not be find out directly by our own eyes. Measurements of light polarization are used in many fields, such as military, astronomy, medical and so on.There are two kinds method in polarization measurement in general:Division-of-amplitude and Polarization modulation. This paper presents a new polarization modulation measurement model- Dual Liquid Crystal polarization measurement system.We use the electrically controlled birefringence properties of the liquid crystal and the DSP chip to achieve the Dual liquid crystal polarization measurement system, which can measure the polarization state of the incident light quickly and accurately without any rotating optical components .The main content of this paper is:(a) Improving on the process of assembling Liquid Crystal Modulator (LCM) and the research of electrically controlled birefringence properties of LCM. To realize the Dual Liquid Crystal polarization measurement system, we fit the electrically controlled birefringence characteristics of the LCM and select the appropriate working way of the LCM according the fitting curve. By selecting the appropriate working way, The relationship between the phase shift produced by the LCM and the time is linear.(b) Studying on the application of DSP technology at the Dual Liquid Crystal polarization measurement.We use the programmable DSP chip which is high-speed, accurate and stable to acquire the optical signal, to filter the signal to improve the SNR(Signal to Noise), to process the signal using the polarization measurement algorithms which is designed by us and to show the results. We introduce the DSP into our Dual Liquid Crystal polarization measurement system to improve the precision and the speed of the measurement. |
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