Patent ID: 8779374

Claim:
An apparatus for the in situ monitoring of elemental mercury vapour in a flue gas flow, comprising, a radiant energy source including, a first light source operable to output a first light energy having a wavelength selected at about 253.7 nm+/−1 nm, a second light source operable to output a second light energy having a wavelength selected at about 254 nm+/−20 nm, a light projector lens optically coupled to the radiant energy source and disposed at a first location relative to said flue gas flow, a collector lens assembly disposed at a second location relative said flue gas flow spaced from the first location, a fibreoptic connector assembly optically connecting the radiant energy source to said light projector lens, the fibreoptic connector assembly including, a first uplead optical fibre optically coupled to the first light source, a second uplead optical fibre optically coupled to the second light source, and an optical coupler optically communicating with the light projector lens and the first and second uplead optical fibres, the optical coupler for mixing input UV light energy from the first and second uplead optical fibres and transmitting mixed light energy to the projector lens, the projector lens being operable to emit at least part of said mixed light energy as a mixed UV light beam across at least part of said flue gas flow, the collector lens assembly operable to receive the mixed UV light beam emitted across said at least part of the flue gas flow, a detector assembly for measuring reference UV light emitted by said light projector lens, the detector assembly comprising at least one spectrometer for measuring at least one of light intensity and light wavelength received by the collector lens assembly.