Patent ID: 7848209
Filing Date: 2010-12-07
Classification: G02F,G11B

Abstract:
1. An optical pickup which performs at least one of recording, reproduction and deletion of information onto an optical recording medium, comprising: three light sources which are configured to emit lights of three wavelengths of λ an object lens which is configured to condense a light coming from each of the three light sources onto the optical recording medium; an aperture switching device which is configured to switch a numerical aperture applied among NA a phase correction device which is configured to change a phase distribution of a beam which passes therethrough; a wavelength plate, configured to transform light of the wavelength λ at least one of a polarization separation optical system for the wavelength λ wherein: said phase correction device is configured to change the phase of an incident beam only within an area in a range approximately between NA said aperture switching device switches a beam diameter according to a wavelength zone using an optical characteristic of any one of reflection, diffraction, and absorption.