| 摘要 |
PURPOSE:To execute the wavelength detection with high accuracy by controlling the position of interference fringes of a reference light so as to be always in a prescribed state. CONSTITUTION:A monitor etalon 32 is irradiated with a reference light 21 generated from a reference light source 20 and light 11 to be detected, and the light which transmits therethrough forms a first and a second interference fringes 33a, 33b corresponding to each wavelength on the detection surface of a photodetector 33. By detecting them by the detector 33, wavelength of the light 11 to be detected is detected. In this case, a signal for showing the detected interference fringes 33a, 33b is inputted to a CPU 40. Subsequently, information of the interference fringe 33a is extracted therefrom and based thereon, by driving a regulator 50 so that the interference fringe 33a become a prescribed position, pressure in an air gap of the etalon 32 is controlled, and by driving a heater or a cooler 60, an ambient temperature of the etalon 32 is controlled. By such a control, the interference fringe 33b shows absolute wavelength of the light 11 to be detected. |
