| 摘要 |
PURPOSE:To prevent the decrease in input to a sensor and to increase an S/N ratio by arranging an optical sensor so that it is slanted with respect to the optical axis of the semiconductor laser, in such a way that the reflected light of the incident light from the semiconductor laser does not enter the semiconductor laser again. CONSTITUTION:With respect to the optical axis x of the semiconductor laser 1, is arranged the rectangularly or elliptically shaped sensor 2 whose long side or major axis is (m) and short side or minor axis is (n). The short side or minor axis (n) of said sensor 2 is slanted by the angle theta with respect to the optical axis (x) of the laser 1. The configuration is so determined that the reflected light of the incident light from the laser is not allowed to enter the laser, and long side m>short side (n). Thus, all the light entering the sensor 2 can be sensed almost perfectly. The sensed and amplified voltage from said sensor 2 is compared with a reference voltage from a reference voltage generator 4 in a voltage comparator 5. A driver 6 is controlled by the output of the comparator, and the light output of the laser 1 is controlled. Thus, the decrease in input to the sensor 2 is prevented, and the S/N ratio can be increased. |
