Patent ID: 7154837
Filing Date: 2006-12-26
Classification: B82Y,G02F,G11B

Abstract:
1. An optical pickup that is provided in an information recording/reproducing device and performs both information recording and information reproduction on/from an information carrier by irradiating the information carrier with light, comprising: a coherent light source; a focusing optical system that converges and directs light from the coherent light source onto an information carrier; and a spot size adjustor that adjusts a size of a light spot so that a size of a light snot in a direction perpendicular to an information track is d wherein the spat size adjustor includes: a variable wavelength plate that is disposed between the coherent light source and the focusing optical system and that is capable of varying a quantity of a phase shift; and a variable polarization phase filter tat is disposed between the variable wavelength plate and the focusing optical system and is divided into at least four regions to produce a phase difference in the direction perpendicular to the information track of the information carrier, so as to provide a phase shift of a desired quantity to only a polarized component of a first polarization type among the light from the coherent light source, the optical pickup further comprising: a polarized light separator that separates reflected light from the information carrier into a polarized component of the first polarization type, and a polarized component of a second polarization type that is different from the first polarization type; a first photodetector that detects the polarized component of the first polarization type of the reflected light from the information carrier; and a second photodetector that detects the polarized component of the second polarization type of the reflected light from the information carrier.