The calibration of the spectroscopic diode laser sensor for the water vapour diagnostics at output of singlet oxygen generator for COIL

摘要

AlGaAs/GaAs quantum-well diode laser (824 run) with the short external cavity was used for water diagnostics in the pumped out gas cell. The laser provided the 63 GHz continuous tuning of the optical frequency by the scanning of a pump current and a spectral linewidth of oscillation was less than 0,2 GHz. The experimentally obtained dependence of a second derivative amplitude on the vapour pressure coincides well with the calculated curve in the range of 0,4-20 Torr. The change of output signal close to linear was recorded at a pressure in the sample gas cell less than 5 Torr. The minimum concentration of H_2O, which is still measured by the diode laser sensor is estimated at a level 1,5x10~(15) molecule/CM~3.