A NEW METHOD FOR CALIBRATION OF PHOTOELASTIC MODULATOR
光弹调制器定标新方法

The traditional calibration method of PEM is elaborated fromtheory.It is found that the method searching the fundamental component maximum has some disadvantages:the accuracy is difficult to improve and it can not calibrate for multi-wavelength.By analyzing the first derivatives of Bessel functions J0（A） and J1（A）,we know that the absolute value of the first derivative of J0（A） is maximum in the range of 103°～108°.Another configuration to accurate calibration by detected the dc component is got according to the fact.In this configuration,a small change of peak retardation will cause an obvious change of dc component in the range of 103°～108°.Therefore,the accuracy of calibrtion is high in this configuration.Concurrently,calibration can be performing in broad wavelength band.