ELECTRODELESS DISCHARGE LAMP

PURPOSE:To concentrate a distribution of luminous spectra within a specific range of wavelength region and to realize an effective use of radiant energy by limiting the filling amount per unit volume for aluminium which, in addition to mercury and a starting inert gas, is filled into a lamp. CONSTITUTION:When the filling amount of aluminium, in addition to mercury and a starting inert gas, filled into an electrodeless discharge lamp excited by microwaves so as to be luminous is limitted to be 2.5X10 gram atoms/cc or more and 15X10 gram atoms/cc or less, 365 nm radiation of mercury is suppressed and luminous spectra can be concentrated within a 380 nm to 410 nm wavelength region in which a main luminous spectrum exists in the vicinity of 390 nm. Subsequently, a radiation dose of ultraviolet rays of 380 nm or less is decreased and so radiant energy of the lamp is effectively utilized.