| 摘要 |
PURPOSE:To achieve the stabilization of wavelengths and the correction of a refractive index simultaneously, by arranging a laser interferometer system so that the length of the dead path does not vary, controlling the oscillation wavelength of a laser oscillator in such a way that the wavelength of the laser is always constant. CONSTITUTION:A quarter wavelength plate 14 and a mirror 15 are bonded to one side of a polarizing beam splitter 4 and further, another quarter wavelength plate 16 is bonded to the other side as well. A mirror 6 is disposed so that the mirror faces the bonded face of the foregoing wavelength 16. For example, the mirror is connected to an interferometer 4 by a supporting member 5 consisting of materials such as a super unvar and the like having a smaller linear expansion coefficient, and the distance between the mirror 6 and the interferometer 4 is almost invariable. When oscillation wavelengths of a laser oscillator 1 are controlled by controlling voltages impressed to a heater 3 with a laser wavelength control device 12 so that an output of a displacement measurement device 11 does not vary, the optical path between the interferometer 4 and the mirror 6 is kept at a constant wave number. Thus, the laser wavelength is corrected and stabilized in the environment on the optical path. |
