Simultaneous measurement of phase retardation and optic axis of wave plates

A simple method used for simultaneous measurement of phase retardation and optic axis of wave plate by employing 1/4 wave plate is demonstrated. The theoretical analysis of the measuring principle is presented in detail. In the measurement, after adjusting a standard 1/4 wave plate and the fast (slow) axis of the plate to be measured parallel to the pass axis of the polarizer, the plate to be measured is rotated by 450 counterclockwisly. A stepping motor is used to rotate the analyzer. The experimental data are collected by a photodetector and then sent to a computer. According to the output data curve, the phase retardation and optic axis of the plate to be measured can be obtained simultaneously. To test the feasibility of the method, a λ /2 and a λ /8 wave plates are used as examples to demonstrate the measurement procedures. The phase retardation measurement accuracy is better than 0.5 × 10-2. This method can be used to measure the arbitrary phase retardation conveniently. © 2007 Tianjin University of Technology.