PHOTODETECTOR HAVING FREQUENCY CONVERSION COAT LAYER AND LASER SYSTEM USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a photodetector with less space and cost wherein the dark current increase problem accompanying a laser ultraviolet beam is avoided. SOLUTION: For the ultraviolet beam detecting system 100, the increase factor of a dark current background relative to the total accumulated irradiation dose is suppressed, and a parameter of an ultraviolet radiation source such as ArF-excimer laser is monitored with no rapid degradation in signal by allowing the signal to be overlaid with a dark current background. A detector 102 of the system 100 includes a photosensitive element comprising a wavelength conversion coat layer 104 on the surface. The coat layer 104 is deposited (laminated) directly on the photosensitive element, and absorbs incident ultraviolet light and releases visible light in the direction toward the photosensitive element again. The coat layer 104 minimizes a dark current background which appears when the photosensitive element is irradiated directly with an incident ultraviolet ray 106 if there is more, for prolonging the service life of the photosensitive element.