METHOD AND APPARATUS FOR MONITORING AIR POLLUTANT

摘要

PROBLEM TO BE SOLVED: To simultaneously generate beams having an 'ON-wavelength' and an 'OFF-wavelength' by using one beam source, and to measure the concentration of air pollutants with high accuracy and high sensitivity. SOLUTION: An etalon plate 14 is inserted in the resonator of a laser generation part 11 and laser beams with an ON-wavelength and an OFF-wavelength are generated simultaneously from the laser generation part 11 to cause irradiation gas 17 to be measured through an optical system 16 and the reflected laser beams from the gas to be measured are condensed by a condensing optical system 21 to be spectrally diffracted into the ON-wavelength and the OFF- wavelength by a dichroic mirror 22. The spectrally diffracted ON-wavelength are detected by an ON-wavelength detector 23 to be inputted to a processor 25, while the spectrally diffracted OFF-wavelength is detected by an OFF- wavelength detector 24 to be inputted to the processor 25. The processor 25 celculates the concentration of pollutants in the gas 17 to be measured from the detection signals of the ON- and OFF-wavelengths and outputs the calculated result to a monitor device 16 to display the same.