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针对现有光弹调制器标定方法的不足,提出了一种精确标定光弹调制器的新方法。首先利用起偏器、波片、光弹调制器和检偏器构成标定光路,通过寻找探测信号基频分量的极大值进行粗略标定,使光弹调制器的峰值延迟量处在1.841rad附近。然后撤走波片形成光弹调制器的精确标定光路,在检偏器旋转90°前后获得探测信号的直流分量和二次谐波分量。最后利用这两种探测信号的直流分量和二次谐波分量精确地计算出光弹调制器的峰值延迟量。实验验证了此光弹调制器标定方法,实验结果表明其标定误差仅为0.7%。在此光弹调制器标定方法中,光弹调制器的标定精度和入射光强、电路参量无关。同时,标定要求的峰值延迟量小,非常适合于光弹调制器在其使用波长范围长波段的标定。
Aiming at the shortcomings of the calibration method of the existing photoelastic modulator, a new method of accurately calibrating the photoelastic modulator is proposed. Firstly, the calibrated optical path is composed of polarizer, wave plate, photoelastic modulator and analyzer. By finding the maximum value of the fundamental frequency component of the detection signal, the peak delay of the photoelastic modulator is around 1.841rad . Then the wave plate is evacuated to form an accurate calibrated optical path of the photoelastic modulator, and the DC component and the second harmonic component of the detection signal are obtained before and after the analyzer rotates by 90 °. Finally, the peak delay of the photoelastic modulator is precisely calculated by using the DC component and the second harmonic component of the two detection signals. The calibration of this photoelastic modulator was verified by experiments. The experimental results show that the calibration error is only 0.7%. In this photoelastic modulator calibration method, the calibration accuracy of the photoelastic modulator has nothing to do with the incident light intensity and the circuit parameter. At the same time, the calibration requires a small amount of peak delay and is ideally suited for calibration of the photoelastic modulator over a long wavelength band of its used wavelength range.