Light pick-up device

Application Number: 00126498
Application Date: 2000.08.31
Publication Number: 1286465
Publication Date: 2001.03.07
Priority Information: 1999/8/31 JP 244639/99
International: G11B7/135
Applicant(s) Name: K.K. Sankyo Seiko Mfg. Seisakusho
Inventor(s) Name: Takeda Masashi
Patent Agency Code: 31100
Patent Agent: shen zhaokun
Abstract The present invention provides a multi-light source type optical pickup device having low cost and high general applicability. A dual light source type optical pickup device is equipped with a light source unit which incorporates a first laser light source 35 and a common photodetector 36, and with an individual light source 4 which is a second laser light source, the laser beam from each light source being guided to a common optical path L by a prism 5 for synthesizing optical paths. Return light from an optical disk 10 is passed through the prism and received by the common photodetector inside the light source unit. Diffraction elements 32, 42 for forming three beams are individually capable of rotary adjustment. The photodetector are commonly used. Also, both laser beams are free from optical axis deviation; hence, the characteristical changes in the optical system incident to the movement of the objective lens become symmetrical to the center optical axis, dispensing with a special compensating circuit.