Patent ID: 6346695
Filing Date: 2002-02-12
Classification: G01J,G11B

Abstract:
A pickup device comprising:a light source for emitting a light beam; an optical system for separating the light beam into a main-portion and at least one sub-portion and for guiding the main-portion of the light beam to an information storage medium, the main-portion being a center portion of the light beam and the sub-portion being a portion of the light beam other than the main portion, the optical system comprising an interrupting member for partially interrupting the light beam from the light source and passing only the main-portion and the sub-portion of the light beam, the interrupting member comprising at least an aperture through which the sub-portion of the light beam passes; a casing for covering a light emitting part of the light source to receive a whole portion of the light beam emitted by the light source, the interrupting member being disposed on the casing at a position receiving the light beam from the light source; a monitor detector for receiving the sub-portion of the light beam and for outputting a detection signal; and a controller for controlling an output power of the light beam emitted by the light source based on the detection signal.