Ultraviolet transmitting filter glasses of the UG - group find wide use in UV lighting situations. In this area the simultaneous presence of visible radiation is frequently undesirable, as especially in the excitation of materials with Ultraviolet radiation for producing visible luminescence the filter must guarantee a significantly strong suppression of the visible radiation of the radiation source. This can be achieved in Schott UG5, Schott UG11, for example, by an approximate selection of the filter thickness. Schott UG5 filter glass is especially suited for the 254nm line of a low-pressure mercury lamp, while Schott UG11 is frequently used for the selection of the 365nm mercury line.