Optical configuration optimization and calibration for the POINT system on EAST.

Area of Science:

• Physics
• Optical Engineering

Background:

• Polarimeter calibration is essential for accurate measurements.
• Anisotropic mesh beam splitters distort the polarization state of light.

Purpose of the Study:

• To develop a calibration method for polarimeters that minimizes distortions.
• To improve the accuracy of Faraday rotation measurements.

Main Methods:

• Utilized a rotating crystal quartz half-wave plate (λ/2-waveplate) to replace plasma.
• Obtained the ratio of measured to known rotation angles for calibration.
• Optimized the system configuration to eliminate polarization distortion.

Main Results:

• The rotating waveplate method effectively calibrates the polarimeter.
• Distortions introduced by wire-mesh beam splitters were minimized.
• Polarization state distortion was effectively eliminated with the novel configuration.

Conclusions:

• The proposed calibration technique enhances polarimeter accuracy.
• This method provides a reliable way to determine calibration factors.
• The optimized configuration successfully mitigates beam splitter-induced polarization errors.