US Patent 7476866 Apparatus and method for detection of vacuum ultraviolet radiation

Vacuum ultraviolet radiation detection apparatus (10) comprises a radiation detector (30) in a chamber (12). The detector (30) receives ultraviolet radiation from a radiation source (36). The chamber is evacuated using a dry vacuum pump (18) to a relatively poor vacuum of no less than 5 Pa. UV transparent gas is supplied from a gas supply (26), into the chamber (12) at a relatively low flow rate (around 0.1 liters/minute) so as to provide an overall pressure in the chamber (12) of between 100 and 1,000 Pa. The use of a relatively inexpensive pump coupled with a lower gas flow rate provides significant cost savings.