Precise surface measurement by local sampling phase shifting technique

摘要

Conventional phase shifting methods do not have enough phase resolution less than ±1 deg. Although images sampling times for the phase shifting analysis have to be increased for the easy solution of this problem, there are some limits to get more images than five because of limited capacity of memory and detecting time of the image. In order to detect phase distribution of interferogram with high resolution, a local-sampling phase shifting technique is proposed. It is useful to increase the resolution of detected light intensity in the same quantized error. This method is verified by birefringence measurement in 256 x 256 values in short time with ±0.02 deg of phase accuracy. This method is applied to measure surface profile measurement.