| 摘要 |
PURPOSE:To control the emission of a laser beam and to ensure the safety to the human body by a method wherein a circuit, which controls the driving current of a laser according to the variation of ambient temperatures, and a circuit, which controls the feed to the laser when the proper driving current at the ambient temperatures has exceeded the tolerance limits, are provided. CONSTITUTION:A feedback circuit provided with a thermistor RT1 is provided to an operational amplifier OP1 and a transistor Tr1, which impress constant voltage supplied from a constant-voltage power source REG to drive a semiconductor laser LD. This laser LD is modulated by the output of an oscillating circuit OSL and the driving current of this laser LD is detected by a differential amplifier OP2. This detected driving current and the constant voltage supplied from the power source REG are applied to an operational amplifier OP4, while the driving current is controlled by ambient temperatures detected by a thermistor RT2, and, the driving current of the laser is controlled according to the variation of the ambient temperatures and when the proper driving current at the ambient temperatures has exceeded the tolerance limits, the feed to the laser LD is controlled by the output of an AND circuit, thereby ensuring the safety to the human body. |
