Simultaneous Measurement of Phase Retardation and Fast-Axis Angle of Phase Retardation Plate

A phase retardation plate, such as a quarter-wave plate, is able to control the state of polarization. Thus, a precise simultaneous determination of phase delay between two eigen-polarization states and its fast-axis angle is essential to the performance of the phase retardation plate to control the state of polarization. Consequently, the measurement of the two-dimensional spatiotemporal distribution of phase retardation and the fast-axis angle become crucial when a large-area of phase retardation plate, such as that for a liquid crystal display, is characterized, due to the inhomogeneity of the retardation plate. In order to measure the linear birefringence parameters, phase retardation and fast-axis angle at the same time, a novel polarized optical heterodyne interferometer is developed, with which the parameters of a quarter-wave plate are successfully measured and verified. The features of this device are (1) a common-path configuration, (2) measurement independent of laser intensity, and (3) the capability of simultaneously determining the spatiotemporal distributions of phase retardation and fast-axis angle of a retardation plate.