位相ステップ法を用いた複屈折位相差測定における測定精度の向上

抄録

An apparatus for measuring a birefringence distribution of a large area at a high speed is desired. Therefore, the phase-stepping method is suitable for this because there are no moving parts in the equipment. In this research, we aim to develop a calculation procedure to eliminate errors resulting from tolerances of optical elements constituting the apparatus. Measurement of birefringence phase difference was carried out using a device composed of laser, attenuator, polarizer, quarter-wave plate, specimen, analyzer and CCD camera. As a result, the coefficient of variation of the measured birefringence phase difference was as high as 8.64%. The cause is considered to be the effect of tolerance and assembly error of the optical elements constituting the apparatus. We thought that this coefficient of variation can be made smaller by approximating the obtained brightness value to the theoretical value. The obtained brightness value was compared with the theoretical value and error of the birefringence phase difference was investigated. As a result, it was found that error of the birefringence phase difference can be reduced by using the correction function for approximating the obtained brightness value to the theoretical value. It was also found that accurate measurement of birefringence amount of unknown sample is possible by using this correction function and theoretical value.