METHOD AND DEVICE FOR DETECTING LIGHT

摘要

PURPOSE:To continuously obtain detection value of light which has reproducibility and is accurate for a long time in such a state that a window for detecting light is always made cloudless by providing the window to the position for receiving light which is used at a time for forming a thin film or is secondarily generated through a transparent base plate formed with the thin film. CONSTITUTION:A target 11 and an anode 12 are provided to a forming device 1 for a thin film and high voltage is impressed between both two under vacuum to cause flow discharge and gas such as Ar introduced into the discharged space is made to a state of plasma 14. Ar<+> made to positive ions in the plasma 14 is allowed to collide against the surface of the target 11 and deposited on a transparent base plate arranged on the anode 12 to form the thin film. The detection light 2 of one part of plasma 14 is passed through the base plate 13 and is reached to a photodetector 3 through a window 6 for detecting light. A spectrometer 31 constituting the photodetector 3 separates light different in wavelength and energy of light having detected wavelength is converted into current value with a photoelectric tube 32 and it is amplified with a current amplifier 33 and output. In this invention, such possibilities where the window for detecting light is made cloudy by the sticking of a material for forming the thin film on the window are not caused because light is received through the transparent base plate.