Method of measuring the practical retardance and judging the fast or slow axis of a quarter-wave plate

A method used for the measurement of the practical retardance value (not considering an overall ambiguity modulo 2π) and the determination of the fast or slow axis of a quarter-wave plate employing two polaroids and a right-angle prism is reported. The theoretical analysis of the principle is given, the formula of uncertainty is derived, and the effects of each factor upon the uncertainty are simulated using a computer. The working conditions of this method are discussed. An application example is given and the measured result of the example is verified exploiting the results of a proving test and computer simulation, which indicate that the method is feasible. Furthermore, this method has the advantages such as easy to obtain the optical devices needed, simple to operate, and accurate etc.