Patent ID: 6188061
Filing Date: 2001-02-13
Classification: G11B

Abstract:
An optical pickup device comprising:a silicon substrate disposed parallel with an optical disc and provided with optical components thereon;a prism for transmitting an incident beam disposed on the silicon substrate;a laser light source part having a laser light source for generating laser beam, the laser light source part being spaced out from the prism on the silicon substrate;a diffraction grating for diffracting a laser beam irradiated from the laser light source, the diffraction grating being formed on one side surface of the prism which faces the laser light source part;a beam splitter for partially reflecting and partially transmitting the laser beam, the beam splitter being positioned inside of the prism to be slanted by a predetermined angle on the silicon substrate, so that the laser beam irradiated from the laser light source is incident on the beam splitter after having transmitted through the diffraction grating, and then the beam is partially reflected by the beam splitter toward the optical disc which is to be positioned at upper part of the silicon substrate;a selective light-transmitting part formed on an upper surface of the prism for transmitting the laser beam proceeding to the disc after being reflected by the beam splitter, the selective light-transmitting part having an inner circular part for transmitting the laser beam with a first transmittance and a peripheral portion for transmitting the laser beam with a second transmittance;a reflecting layer formed on a lower surface of the prism, the reflecting layer reflecting the laser beam partially transmitted through the beam splitter after being reflected from the optical disc;a light-receiving part formed on an upper surface of the prism for receiving the laser beam reflected by the reflecting layer; andan objective lens disposed between the prism and the optical disc for permitting the laser beam to focus on the disc via the prism,wherein a difference between spot sizes focusing on the disc is adjustable by properly regulating an outermost angle of incidence of the laser beam which is transmitted through the inner circular portion of the selective light-transmitting part.