A Computer-Based Laser System for the Diagnostics of Hydrogen in Gas Mixtures

A computer-based laser system for the selective diagnostics of hydrogen in gas mixtures based on the coherent anti-Stokes Raman scattering (CARS) method using biharmonic pumping on the basis of stimulated Raman scattering (SRS) is developed. The system includes a generator of single-mode and single-frequency laser radiation with one Nd3+:YAG active element, a frequency converter on a KTP crystal, an SRS oscillator on compressed hydrogen, measurement and reference CARS cells, and an optical and electronic system for recording the CARS signal. The system operates under the control of an IBM-compatible computer through a data input/output card based on a PCI bus. The system ensures the selective detection of hydrogen in gas mixtures at a total pressure of 1 kPa with a repetition rate of up to 10 Hz at a sensitivity of 10–11mol/cm3, which at this pressure approximately corresponds to 20 ppm.