| 摘要 |
PURPOSE:To prevent false control of output, by constituting a photo-sensing part by using a photoelectric transducer to which a resistor having a temperature coefficient to compensate the temperature change is connected parallel. CONSTITUTION:Laser light output from an internal mirror type air-cooling argon laser tube 1 enters a beam splitter 2, by which the light is divided into laser output light 3 and laser reflected light 4 turning to a signal for light feedback. A photo sensing part 7 is constituted of a photodiode 5 and a load resistor 6 having a high positive temperature coefficient, which resistor is connected parallel to said diode. Output terminal voltage of the load resistor 6 is fed back to an output controlling part. By selecting the coefficient of the load resistor so as to compensate temperature characteristics of the photoelectric transducer, the detected signal can be kept constant, even if the temperature rises and the output of photodiode decreases, because the resistance value of the resistor simultaneously increases. |
