Optical pickup using a plano-convex lens as an objective lens for focusing two light beams

Abstract

A scanning device is designed for optically scanning a first record carrier (1) having a first information plane (3) and a first transparent layer (2) of a first thickness and for scanning a second record carrier (18) having a second information plane (20) and a second transparent layer (19) of a second thickness different from the first thickness. The device comprises a radiation source (5, 22) for generating a radiation beam (6, 23) and an objective lens (9) for focusing the radiation beam through one of the transparent layers on one of the information layers. The radiation source comprising means for adapting the vergency of the radiation beam to a first value for scanning the first record carrier and to a second value for scanning the second record carrier. The objective lens has a convex surface (28) and a concave surface (29), the convex surface facing towards the radiation source. The combination of the change in vergency and the concave surface provides a large field of the objective lens, both when scanning the first and second record carrier.

Dependencies are inferred from the claim text.