OPTICAL APPARATUS FOR WRITING AND READING INFORMATION RETAINING MEDIUM

摘要

System comprising means of transmitting two radiations polarised in the same direction and of different wavelengths lambda 1 and lambda 2). This system also comprises optical means comprising at least one splitter element (20), a quarter wave plate (21) and focusing optics (L3 and L4) making it possible to focus onto two photodetector units (DA and DB) the reading and enregistering components of the composite beam reflected on the information medium (5).