Temperature measurement method of the ultraviolet light transmitting member, the temperature measuring device of the ultraviolet light transmitting member, the light source apparatus

Temperature measurable temperature measuring method of the ultraviolet light transmitting member in a straightforward construction, to provide a temperature measuring device. One embodiment illustrating the present invention is a temperature measuring device for measuring the temperature of the ultraviolet light transmitting member that transmits ultraviolet light. The temperature measuring device 2 includes a spectroscopic measurement unit 20 for detecting the intensity distribution of the ultraviolet light UV1 which has passed through the ultraviolet light transmitting member, the absorption edge of ultraviolet light transmitting member from the detected intensity distribution of the ultraviolet light by spectroscopic measurement section 20 calculated wavelength, and an arithmetic processing unit 25 for deriving the temperature of the ultraviolet light transmitting member on the basis of the absorption edge wavelength obtained.