Light from a Mercury Vapor UV lamp (10) passes through a sapphire window (2), and then through the process stream (1).
The resulting light is split by a beam-splitter (3). The channel 1 beam is filtered by a UV filter (4) and is detected by the channel 1 photo diode (5). The channel 2 beam is filtered by a UV filter (6) and is detected by the channel 2 photo diode (7).
The narrow-band pass UV filters block all wavelengths except the specified UV wavelengths. The photocurrents induced are directly proportional to the remaining light intensity at this wavelength.
Installed within the lamp assembly are two lamp reference filters and 2 lamp reference photo diodes (8, 9). This compensates for any variations or intensity fluctuations of the UV lamp at the specific channel 1 and channel 2 wavelengths.
The resulting photocurrents are precisely amplified, converted, and analyzed by the converter. The converter provides real time measurements and can send outputs to the process control system.
