A crystal filter and a method of making a crystal filter capable of transmitting
radiation within a particular pass band is disclosed. The crystal filter is particularly
appropriate for a UV detection system, where the pass band is between about 200
to about 350 nm. A UV detection system incorporating the crystal filter is also
described. One embodiment of crystal filter is formed from a single-crystal transparent
host, such as a fluoride host, codoped with lanthanide or actinide fluorides and
lanthanide or actinide nitrides, oxides, borides, carbides or hydroxides. Filter
crystals according to the present invention can be grown by various crystal growth
methods, including Czochralski and Bridgeman crystal growth methods.
