JPS6448019A - Polarized light separating composite prism - Google Patents

Abstract

PURPOSE:To eliminate a shift of an optical axis caused by thickness of a polarized light separating film, by providing the polarized light separating film and a reflecting film on two prisms, and constituting said prisms so that an S wave is reflected by the respective films, a P wave transmits through the separating film, and both polarized light components are synthesized again. CONSTITUTION:An S wave of a light beam which has been made incident from the lower direction of a prism 41 is reflected by the surface of a polarized light separating film 45, and a P wave passes through the film 45, reflected by a reflecting film 46, becomes parallel rays and made incident on a polarized light control means 58. When the magnetic field direction is an arrow C by a switch 59, a plane of polarization is saved and made incident on a prism 51, and an S wave is reflected by the respective surfaces of a reflecting film 56 and polarized light separating film 55, 57, and a P wave transmits through the film 55 and reflected by the bottom face of the film 57, and optical axes OPA and OAS coincide and emitted in the A direction. As for the film 45 and 57, the same one is used and the emitted optical axes are allowed to coincide entirely irrespective of thickness of the polarized light separating film, and a loss of optical power can be minimized. In this regard, by setting the magnetic field direction to the D direction, the emission can be executed in the B direction.