QUARTZ GLASS FOR SHORT WAVE LENGTH ULTRAVIOLET RAY, DISCHARGE LAMP USING THE SAME, CONTAINER THEREFOR AND ULTRAVIOLET IRRADIATION APPARATUS

摘要

A quartz glass to be used through exposure to an ultraviolet ray having a wave length of 200 nm or less, characterized in that it is produced from natural rock-crystal or silica sand, has a total content of sodium, potassium, titanium and iron of 2.5 ppm or less and contains an OH group in an amount of 10 ppm or more; and an ultraviolet irradiation apparatus wherein the quartz glass is used as the material of a bulb (11) of a light emitting tube of an ultraviolet discharge lamp (L), and as the material of an ultraviolet-transmittable outer tube or protecting tube (20) housing the ultraviolet discharge lamp. The quartz glass is improved with respect to the lowering of the transmittance of an ultraviolet ray in a shorter wave length region with the elapse of time, which leads to the provision of a discharge lump and an ultraviolet irradiation apparatus which are greatly improved in the degree of retention of ultraviolet ray strength, and thus can be operated at a reduced cost and with saving energy.