DUAL LAYER READOUT WITH IMPROVED TOLERANCES

摘要

An optical scanning device for scanning an optical record carrier (OD) with an objective lens (12) for converging a radiation beam to a spot (18) on an information layer (3,4) of the record carrier (OD) , and an optical correcting system (10, 100) for changing the vergence of the radiation beam and the amount of spherical aberration in the radiation beam towards the objective lens, wherein the vergence and the amount of spherical aberration in the radiation beam can be adapted independently. The optical correcting system (10, 100) comprises a set of fluids (A, B) having a first meniscus (114, 136) having a first radius and a second meniscus (115, 138) having a second radius, the first radius and second radius being separately adaptable.