| 摘要 |
PURPOSE:To obtain a laser beam having a stable oscillation wavelength by detecting variation of a monitoring means itself, obtaining monitor output to correct an amount corresponding to the variation, and detecting an wavelength corresponding to the wavelength of the laser oscillation. CONSTITUTION:A reference light source 17 is provided that lets reference light of a stable wavelength strike into a wavelength-monitoring means 2-4, 7 with almost the same axis as that of a part of a laser beam. The wavelength- monitoring means 2-4, 7 is provided with monitoring etalons 2 which make the first interference fringe corresponding to the wavelength of the laser beam at a position distant from the center line and besides the second interference fringe corresponding to the wavelength of the reference light between the center line and the first interference fringe, and a photodetector 7 detecting the relative positional relation between the first and the second interference fringes photoelectrically. Then, a processing device 13 detects a change of the wavelength of the laser beam according to this relative positional relation. And, this makes it possible to obtain a laser beam having a stable wavelength. |
