LAUSR

Abstract The photoelastic modulator (PEM) is an optical modulation device which is widely used in optical detections. In this paper, we propose a high-precision and large-scale method for calibrating the peak retardations of PEM based on compound Bessel function. By applying compound Bessel function instead of the single Bessel function, the uncertainty of peak retardation calibration result decreases more than two times and the calibration scale expands nearly two times. Further, the second harmonic component is substituted for the DC component to reduce the random errors. In the experiment, a PEM is calibrated and the calibration result obtained for peak retardation is linear to the setting value in scale 0.15–2.5 rad. A dead zone appears in region 0 to 0.15 rad with value 0.233 rad. The experiment demonstrates that the relative uncertainty of peak retardation decreases from 2.5 % to less than 1 %.