High efficiency precision laser beam switch

摘要

An optical beam switch is provided in a multiple beam optical disc record and playback system. Current systems for very high data rate optical disc mass memory apparatus include requirements for near-continuous recording of data using two separate turntables in a single apparatus. To reduce cost and complexities in the system as well as power requirements, the optical system includes a beam switch that allows a single record laser and modulator to be shared between two turntables. In accordance with the system a half-wave plate is shifted into and out of the beam path to effect polarization change of the light beam. A polarizing beam splitter, which follows the half-wave plate in the beam path, shifts the light beam in one of two directions depending upon the polarization of the light beam or, in other words, the position of the half-wave plate.