Patent ID: 6408116
Filing Date: 2002-06-18
Classification: G11B

Abstract:
A light guide path element for use in an optical pickup which irradiates a light beam emitted by a light source via an optical system onto an information storage medium and receives the light beam reflected therefrom, the light guide path element comprising:a waveguide layer for propagating the light beam; a grating for input-coupling a part of the light beam reflected by the information storage medium with the waveguide layer and for transmitting a remaining part of the light beam; and a light receiving portion for receiving the light beam transmitted through the grating, wherein the waveguide layer, the grating and the light receiving portion are formed in a laminated manner to form a laminate structure, wherein the grating comprises a first grating pattern adapted to an irradiation state of the light beam when the information storage medium and the optical system move away from each other by a predetermined distance to maximize a coupling efficiency with the waveguide layer, and a second grating pattern adapted to an irradiation state of the light beam when the information storage medium and the optical system approach each other by the predetermined distance to maximize a coupling efficiency with the waveguide layer, and wherein the light receiving portion comprises a first light receiving area corresponding to the first grating pattern and a second light receiving area corresponding to the second grating pattern.