A high-precision quasi-optical polarizer for Zeeman splitting observations

A series of grooved dielectric quarter-wave plates was made for radio astro nomical Zeeman splitting observations at millimeter wavelengths. To meet th e stringent requirements on reflection and polarization purity, a design me thod was formulated based on optimization of multiple reflections. The meth od solves the problem of achieving low reflections for both polarization co mponents while attaining high purity of circular polarization, Several plat es have been manufactured, tested, and used successfully for astronomical o bservations.