| 摘要 |
PURPOSE:To increase oscillation delay time, widen the pulse width of a pulse signal, and keep always the pulse width of light output constant by a method wherein input pulse voltage is controlled with a threshold voltage controlled by an APC circuit, and the pulse width is previously set long based on the threshold voltage. CONSTITUTION:The threshold voltage of a gate 5 is controlled by an APC control voltage. The rise time and the fall time of a wave form of the pulse input to the gate 5 are lengthened as the result of band limiting. From the gate 6, therefore, a pulse whose width is controlled by the APC control voltage is output. The output pulse signal from the gate 5 is input to a laser diode driving circuit 6, and a current is made to flow in the laser diode 7 according to the above pulse signal. The laser diode 7 emits light by the current. The light output of the laser diode 7 is input to a photo diode 8; the output from the photo diode 8 is amplified by an amplifier 9 and fed back to the laser diode driving circuit 6. In this manner, the light output of the laser diode 7 is controlled so as to be constant. |
