| 摘要 |
PURPOSE:To improve measuring accuracy by connecting an operational amplifier which amplifies a photo current to an output side of photo diode and connecting an amplifier which generates reverse bias voltage through detection of measuring output to the ground side. CONSTITUTION:An amplifier A1 connected to the output side of photo diode 1 shows a voltage output obtained by amplifying a photo current from a photo diode 1 and a signal current is converted to a voltage. An operational amplifier A2 connected to the ground side of photo diode 1 detects an absolute value of measuring output, converts a sum of gain into a required reverse bias voltage and then supplies it to the photo diode 1. In case the light is weak, a bias voltage is almost zero as the measure for dark current. |
