Polariscope for simultaneous measurement of the principal axis and the phase retardation by use of two phase-locked extractions

摘要

A novel polariscope with electro-optic modulation that is capable of simultaneous measurement of the principal axis and the phase retardation of an optical linear birefringent medium by means of two phase-locked extractions is described. A phase compensator is used to suppress the transmission phase-retardation effect of the beam splitter, thereby enhancing the precision of the measuring performance. The validity of the proposed design is demonstrated by measurement of the principal axis and phase retardation of a quarter-wave plate sample. There are absolute errors of 0.25° on average and 0.58° at maximum in the principal-axis measurement and of 0.75° (0.83%) on average and 3.11° at maximum in the phase-retardation measurement. Meanwhile, the retardation error lies within a 5% uncertainty range of a commercial wave plate. The root-mean-square resolutions for the principal-axis angle and phase-retardation measurements are 0.042° and 0.081°, respectively. Finally, the dynamic ranges of the principal-axis angle measurement and the phase-retardation measurement extend as far as 180°.