Dispersion of the Retardation of a Photoelastic Modulator

Applied Sciences

Kewu Li¹  Xie Han²  Shuang Wang²  Yaning Wang³ 

[1] Engineering and Technology Research Center of Shanxi Province for Opto-Electric Information and Instrument, Taiyuan 030051, China;School of Data Science and Technology, North University of China, Taiyuan 030051, China;School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China;

关键词: polarization modulation;    photoelastic modulator;    dispersion of the retardation;    retardation calibration;   

DOI  :  10.3390/app9020341

来源: DOAJ

【 摘 要 】

Recently, ellipsometry and polarization imaging using photoelastic modulators (PEMs) have been applied to a wide spectral range, from vacuum ultraviolet to the mid-infrared wavelengths. To ensure high accuracy polarization performance, the accurate calibration of the retardation of PEM is crucial. In this report, the dispersion of the retardation of the PEM is studied. According to the operational principle of PEM, their retardation can be separated into independent dispersion and driving terms. The effect attributed to the dispersion on PEM retardation calibration is experimentally explored. These experiments indicate that the dispersion term can be defined in advance using the refractive index of the photoelastic crystal under incident light, and that the driving term is directly proportional to the amplitude of the driving voltage. The calibration method for the retardation amplitude of the PEM, which considers dispersion, is also demonstrated. The results show that the relative deviation between the calibration and actual measurement values of PEM retardation amplitude are less than 1%. This study presents an accurate way to calibrate the PEM retardation and supports the application of PEMs in a wide range of wavelengths.

【 授权许可】

Unknown