| 摘要 |
PURPOSE:To increase the measuring accuracy of the micro-beam for the photometer by connecting the output voltage controller to the voltage source of the pn-junction type photo detector and then controlling the application voltage in accordance with the incident light volume, thus obtaining the photometric value proportional to the optical input of a wide range. CONSTITUTION:Photo diode 1, current detecting resistance 2, voltage source 3 and switch element 4 are connected in series, and output voltage controller 8 is connected to source 3. Then with application of the switch signals to switch control terminal 5, element 4 operates to give switching to the circuit system with every fixed time. And thus the charging current is detected via resistance 2 for junction electrostatic capacity 6 at the switching time of the circuit system. In this case, controller 8 is actuated when the ratio becomes under 10<3> between the optical current and the dark current of diode 1 under the fixed amount of the incident rays. As a result, the application voltage to element 4 is dropped, thus increasing automatically the photometric measurement accuracy at the time of the micro- beam quantity. |
