A Monochromatic Depolarizer*†

Abstract

Up to the present time no image-forming depolarizing filter has been described which will work for monochromatic light. This paper describes a simple monochromatic depolarizer. This depolarizer consists of two variable wave plates whose axes are separated by an angle of 45°. The retardation of the first wave plate varies from zero to 2π. The second wave plate varies from zero to 4π. This variation is made to occur in a time which is short compared to the time constant of the apparatus in which the depolarizer is used. Typical components are Z cut plates of ammonium-dihydrogen-phosphate. The retardation of these plates can be made to vary by applying an electric field along the optic axis.