Light wavelength measuring instrument, light wavelength measuring method and laser apparatus

摘要

In a light wavelength measuring instrument, a wavelength approximated to a wavelength of a light beam to be measured can be simply selected from light beams, whose spectrum distributions are previously known, as a measurement basis of a wavelength of the light beam to be measured. The light wavelength measuring instrument includes: a reference light source for emitting a reference light beam having a known spectrum distribution; a first spectrometer for spectrum-separating at least the reference light beam; a second spectrometer, having higher resolving power than that of the first spectrometer, for spectrum-separating the light beam to be measured and the reference light beam; and a detector for detecting both the light beam to be measured and the reference light beam emitted from the second spectrometer.