Multi-beam optical record and playback apparatus having an improved beam splitter

摘要

A wideband optical disc data record/playback apparatus is provided. The apparatus includes means for splitting the output of a single laser into multiple beams. The record beams are independently modulated and used to simultaneously record data at extremely high rates on the surface of an optical disc. The apparatus is capable of recording 1x1011 bits of data on one surface of an optical disc at data rates of 100 to 300 Mb/s. In addition, a plurality of coplanar low power beams are used for playback and data verification purposes. In the playback mode a single beam is split into a plurality of low power beams and one of the plurality of beams is dithered such that the dithered beam exhibits periodic excursions in a radial direction across the surface of the disc. The dithered beam is used for tracking purposes in both the playback and record mode. In a preferred embodiment the playback beams are split by an optical grating and dithered by an acousto-optic device.