Wavelength detecting apparatus, laser apparatus, and wavelength detecting method

摘要

In a wavelength detecting apparatus using an etalon, a drift in wavelength measurement by the etalon is stabilized and an adverse influence of out gas is eliminated, so that correct wavelength measurement is realized. The wavelength detecting apparatus includes a housing equipped with a port for use of introducing replacement gas, an etalon set inside the housing, and a moisture-absorbing unit for absorbing at least moisture released inside the housing.