| 摘要 |
PURPOSE: To enhance the heat radiating effect of a semiconductor laser and to enhance the reliability of a device by providing one surface of a substrate having high thermal conductivity with a semiconductor laser element and a photodetector and providing the other surface with a holographic element. CONSTITUTION: The light emitted from the semiconductor laser element 22 is reflected by the end face of the photodetector 23 and is made incident through a through-hole 27 disposed at the substrate 25 on the holographic element 24. The zero order light of the element 24 is guided by an objective lens and is made into a light beam to reproduce the information recorded on the optical disk. The light reflected by the optical disk returns backward from the direction when the light is emitted from the element 24. The light beam returning at the element 24 is separated to zero order light and the diffracted light is made incident on the detector 23. A material having the high thermal conductivity is used for the substrate 25. The element 22 which generates heat according to supply electric power is mounted at the substrate 25 having the high thermal conductivity and the heat generated by the element 22 is completely transmitted to the substrate 25. On the other hand, the substrate 25 has a large surface area and comes into contact with the air, by which the high heat radiating effect is obtd. and the temp. rise of the element. 22 is minimized. |
