簡便な偏光測定による新しい複屈折測定法

抄録

This paper introduces the principles and execution of a new technique based on simple polarimetry for minute birefringence measurements. The technique requires only three stepped photoelastic images although conventional phase-stepping methods require four images. To verify the new technique experimentally, two precise crystal wave plates of having 79.1 ± 3.5 and 10.0 ± 4.7 nanometers in retardation were used as specimens. The measurements of the retardation with standard deviation were found to be 77.5 ± 2.61and 10.3 ± 1.11 nanometers respectively, which agreed well and narrowed the deviation in spite of low-level amount of retardation. To estimate the measurement accuracy of the angular orientation of the birefringence, the angular positions of the rotation stage for the specimens were rotated intermittently 10 degrees at a time during the experiments. As a result, the measured offsets of the angular orientations were found to be 10.0 ± 0.906 and 10.0 ± 3.05degrees with standard deviation respectively. It is concluded that the new technique is effective for minute birefringence measurements.