| 摘要 |
PURPOSE:To reduce the quantity of a stray light falling on a light-receiving surface of a photodetector, by fitting a composite element in a state wherein it has a prescribed or more tilt angle. CONSTITUTION:A composite element 4 is fixed in a state of having a tilt angle of Q1 within a plane of the surface of paper being parallel to the optical axis shown by an alternate long and short dash line so that a stray light due to internal reflection of the composite element 4 may not fall on a light-receiving surface of a multisegment photodetector 9 even when the deviation of the optical axis of a semiconductor laser 1 from that of a collimator lens 2 takes place. By tilting the composite element 4 at a prescribed value or more to the optical axis, it is possible to remove only the stray light generated by the internal reflection of the composite element 4 from the light-receiving surface of the multisegment photodetector 9 and thereby to reduce sharply the stray light on the multisegment photodetector 9, even when a change in the relative positions of a point of emission of the semiconductor laser 1 and the collimator lens 2 is taken into consideration. Therefore it is possible to lessen the offset of a focusing error signal and a tracking error signal and thus a sharp improvement in recording-reproducing characteristics can be realized. |
