INSTRUMENT FOR MEASURING CONCENTRATION OF GAS

摘要

PROBLEM TO BE SOLVED: To reduce a concentration measuring error less than before and to enhance measuring accuracy. SOLUTION: One light emitted from a semiconductor laser 24 is emitted to the outside from a measuring light condensing part 3. The measuring light reflected through an atmosphere of gas to be measured accompanied by this emitted light is condensed by the lens 31 of the measuring light condensing part 3 to be detected by a photodetector 32. The electric signal detected by the photodetector 32 is amplified to a predetermined amplification degree by a measuring light amplifying part 4 to be inputted to a receiving signal detection part 5. The measuring light amplifying part 4 is set in gain so that the gain of a (2f) signal becomes larger than that of an (f) signal, and the signals are amplified so that the (f) signal and the (2f) signal become an equal detection level to be inputted to the receiving signal detection part 5. In the receiving signal detection part 5, (f) and (2f) are detected from the inputted signals to be inputted to an operation part 13. In the operation part 13, the concentration of gas to be measured is operated on the basis of the ratio (2f/f) of (f) and (2f) inputted from the receiving signal detection part 5.