Read/write laser-detector-grating unit (LDGU) with an orthogonally-arranged focus and tracking sensor system

摘要: An apparatus and method for providing tracking focus error signals controlling an application of a radiation beam to data track optical storage medium. A signal, indicative the stored on medium, may also be provided. One in accordance with present invention includes source generate beam; transparent substrate arranged between medium; grating splitter formed surface having first, second, third fourth elements separating return reflected diffracted from into portions, respectively. In other embodiments, more or less than four portions could used. The are directed onto detector array. first second separate along plane substantially parallel reference defined by axis tangent track, resulting used signal. elements, opposite sides adjacent perpendicular plane, source, substrate, array part LDGU contained within single package.