| 摘要 |
PURPOSE:To emit a light at high speed properly by calculating the drive current required for emitting it with a specified value based on the quantity of the emitted light of a semiconductor laser and differential efficiency. CONSTITUTION:CPU 6 seeks the respective quantities of lights emitted by driving a semiconductor laser 1 with two current values, and calculates the differential efficiency as the difference of quantity of light the difference of current. This differential efficiency itself does not change temporally. Next, the semiconductor laser 1 is driven with the specified current value, that is, the emitter current suited to the base current of a transistor 3. And, if one applies the relation of the current and the quantity of light emitted in this case to the differential efficiency, the temporal deviation quantity of the property of the current/quantity of light emitted is sought, whereby the value of the current in case of getting the specified quantity of light emitted can be calculated. Thereby, proper emission can be performed at high speed. |
