Patent ID: 6788636
Filing Date: 2004-09-07
Classification: G02B,G11B

Abstract:
An optical recording/pickup head for use with each of a plurality of optical discs for performing recording/reproduction of information with a respectively different wavelength, the optical recording/pickup head comprising:a first optical source for emitting first light having a relatively short wavelength; a second optical source for emitting second light having a relatively long wavelength; and an objective lens for focusing the first and second light emitted from the first and second optical sources on the information recording surfaces of a respective one of the plurality of optical discs, wherein: said objective lens has a first area for substantially totally transmitting the first light and a second area for diffracting the second light towards an optical axis of the objective lens, and said second area comprises diffraction grooves having a staircase and/or a saw-tooth pattern structure.