Multichannel Raman gas analyzer: the data acquisition and control system. Measurement improvement with blue laser light

In this paper, the data acquisition and control system of a multichannel Raman effect-based gas analysis device is presented, together with the improvements achieved in measurement of gas concentration sensitivities as a result of the operation of the system with a new blue laser-light source. The multichannel Raman gas sensor (MRGS) is based on the linear Raman scattering effect and uses photo multiplier tubes (PMTs) in the photon-counting mode of operation. An embedded microcontroller-based data acquisition and control (MDAC) system collects, digitizes, processes, and stores in real time the data from six photon-counting modules and the accompanying sensors, along with an overall system control through appropriate actuators. Recent advances in the development of solid-state laser sources have enabled the use of a new, stateof-the-art, blue laser for the excitation of the Raman effect. Using this blue laser source, improvements in the sensitivities in measurements of concentration for all tested gases (SO/sub 2/, CO/sub 2/, CO, NO/sub 2/, C/sub 6/H/sub 6/, and N/sub 2/) have been substantiated, compared with the green laser source previously used and reported in a related article.