| 摘要 |
PURPOSE:To reduce the number of parts by forming integrally a light receiving element for reading the disk information with a monitor light receiving element for fixing a quantity of light of a light source. CONSTITUTION:A light beam 22 from a semiconductor laser beam source 21 is reflected by a half-mirror 23 and projected onto a disk 25. A reflected ray from the disk 25 is reflected by the back side of the mirror 23 and received by the light receiving element PD1 of a light receiving element body 27. On the other hand, a part 29 of the light beam 22 is received by the light receiving element PD2 of the element body 27 and fed back to the beam source 21 by a negative feedback circuit 20, so as to fix the quantity of stimulating light emission. The element body 27 consists of a substrate silicon forming an N-layer and P-layers in two places to form a P-N junction via vacant O-layers. Then, the light receiving surface of the element PD1 is on the side of the P-layer, and that of the element PD2 is on the side of N-layer. By this method, the elements PD1 and PD2 are formed integrally with the element body 27, thus reducing the number of parts. |
