Patent ID: 7362688
Filing Date: 2008-04-22
Classification: G11B

Abstract:
1. An optical scanning device for scanning a first and a second type of record carrier in a first and a second mode, respectively, the device comprising a radiation-generating device for generating a radiation beam having at least a first wavelength in the first mode and at least a second wavelength in the second mode, an objective system for forming the radiation beam of the first wavelength to a focus in the first mode on the first type of record carrier and for forming the radiation beam of the second wavelength to a focus in the second mode on the second type of record carrier, and a structured optical element arranged separately with respect to the elements of the objective system in the radiation beam for introducing aberration in the radiation beam of the second wavelength, wherein the aberration introduced by the separate, structured optical element for the second wavelength comprises both a vergence change and a spherical aberration.