Thin optical pickup unit comprising only general-purpose optical parts

摘要

A rising mirror (MIR') reflects a laser beam produced by a semiconductor laser (LD') by a reflecting surface thereof to make the laser beam converge on a signal recording surface of an optical disc (Disc) through an objective lens (OL') and reflects a return beam from the signal recording surface to make a photodetector (PD) detect the return beam. A rising angle (theta') between the reflecting surface of the rising mirror (MIR') and the pickup's lower surface is smaller than 45 degrees. With this structure, optical parts including the semiconductor laser and the photodetector may be arranged in an optical base (OB) with the optical parts inclined to the optical base so that the optical parts are not jutted out the pickup's lower surface downwards.