a substrate 103 as shown in fig5 the crystal structure having the optimum wavelength for the conversion into visible light due to the fluophor 4 is selected in the range from the infrared region to the ultraviolet region by the oscillation wavelength the crystal structures of the semiconductor laser element 1 as shown in table 1 are put into practical use preferably use is made of the crystal structure which stably and continuously oscillates at room temperature to generate relatively high radiant power output such as al x ga 1 x as in 0 7 u03bcm band and 0 8 u03bcm band in 1 x ga x as y p 1 y in 1 u03bcm band and al x ga 1 x in 0 5 p 0 5 in 0 6 u03bcm band further since the semiconductor laser element 1 in the short wavelength region from blue to ultraviolet rays involves a problem in that the life of continuous oscillation is short at room temperature under the present conditions it is possible to use a semiconductor laser element 1 having the structure as follows a semiconductor laser element as shown in fig2 a is arranged such that mercury atoms hg.