Comparison of half-wave phase retarder and quarter-wave phase retarder

Phase retarders (PRs) are space-variant waveplate elements which are usually utilized to generate radial and azimuthal polarization and find the polarization axis. So far, there have been mainly two types of phase retarders: half-wave phase retarder and quarter-wave phase retarder. Their principles are similar while functions are different. Some researchers may feel confused to make a choice between them. The present work aims to provide an engineering reference for choosing phase retarders with half-wave and quarter-wave retardation in practical applications. We make a comparison of the two types of PRs in both principles and applications to show their properties clearly.