A New Measurement Technique of Low-Level Strain Retardation in Optoelectronic Materials

This paper introduces the principles and execution of a new technique for low-level strain retardation measurement, which requires only three phase-stepping images, with precision. It then discusses the potential of this new technique for improving automated photoelasticity. To verify the new technique experimentally, a precise crystal wave plate of having low-level retardation was used as a specimen. The tolerance in retardation was 10.0plusmn4.7 nanometers. The measurements of the retardation with standard deviation using the new technique were also found to be 10.0plusmn4.7 nanometers, which agreed well in spite of low-level amount of retardation. Moreover, the measured offsets of the angular orientation were found to be -0.05plusmn4.46 degrees with standard deviation for angular position of the rotation stage for the specimen. The instrument described in this paper includes beam splitters to measure the influence on these measurements to develop the instrument into an automated one in future research. Finally, it is suggested that an automated photoelasticity will now be possible within an error of around plusmn3nm in retardation and around plusmn5degrees in its related orientation