Near infrared polarimeter based on liquid crystal variable retardes

作者：Zhang Zhiyong^*; Deng Yuanyong; Wang Dongguang; Sun Yingzi; Xuan Weijia

来源：CHINESE JOURNAL OF LASERS-ZHONGGUO JIGUANG, 2010, 37(3): 696-702.

DOI：10.3788/CJL20103703.0696

• Applied optics
• Coronal mass ejection
• Electrooptical modulators
• Extinction ratios
• Hot point
• Liquid crystal variable retarders
• Modulating voltage
• Near Infrared
• Polarization state
• Solar activity
• Solar atmosphere
• Solar physics
• Stokes parameters
• Stokes polarimeter
• System design
• Visible light
• Zeeman effect

Measuring the polarization states of the sunlight with a polarimeter, one can obtain the magnetic field information in the solar atmosphere using the principle of Zeeman effect and study the solar activities such as sun spots, flares and coronal mass ejection (CME). Near infrared polarization measurement has been becoming the frontier and hot point in solar physics. Developing polarimeter at this wavelength can help us to get far more information than visible light and redound to resolving the basic problems of the solar physics. A newly developed near infrared Stokes polarimeter is presented in this paper. In this device, a λ/2 and a 1 λ liquid crystal variable retarders (LCVRs) are employed as the electro-optical modulators and a near infrared polarizer whose extinction ratio is about 10-5 as the analyzer and the temperature control system can keep the temperature within ±0.01 °C, which satisfies the system designs. Compared to the commonly used KD*P electro-optical modulators, liquid crystal retarder can reach any retardation between 0 and maximum only with low modulating voltage and has better transmittance and lager aperture. Furthermore, without any movement units, the speed of alternating the Stokes parameters is significantly improved by 102. And theoretical analysis shows that the crosstalk of this design is limited in the order of 10-3.

• 出版日期2010