| 摘要 |
PURPOSE:To enable a light emitting waveform to be monitored as voltage waveform without impairing stable action in the mean light emitting output of a laser diode by means of a resistance element inserted in series into a photo diode. CONSTITUTION:A light emitting output of a laser diode 1 is transmitted to a photo diode 2 by way of a light wave guide 9 and a light detecting current is outputted from the photo diode 2 according to the light detecting quantity. One end of a resistor 12 is grounded in an AC manner with a condenser 6 so as to enable monitoring through a condenser 13 from the other end of the resistor 12 whereby AC component of the light emitting output waveform from a laser diode 1 is drawn to a terminal 14 to monitor. In this case, since a monitor terminal 14 is separated from a light emitting output stabilizing circuit in a DC manner with a condenser 13, there is no impairing of stability in the light emitting output of the laser diode 1. |
