| 摘要 |
PURPOSE:To hold detection precision constant by keeping the oscillation light wavelength of a laser constant, by controlling an intermittent current supplied to a laser element so that the difference in the absorption value of laser light between two calibration paths differing in gas concentration will be maximized. CONSTITUTION:Laser light emitted from laser element 5 lightens gas 30 to be measured by way of lens 29, concave reflex mirror 26, and beam splitters 19, 20 and 23 and it reflected and focused through corner cube 28, beam splitters 23, 21 and 22, and concave reflex mirror 27 to be detected by detector 6, whose output is processed by microcomputer 7, so that the result will be displayed on recorder 16 or display device 17. To stabilize the laser oscillation light wavelength, a laser exciting current is varied from the threshold value to the upper limit value finely and at the samt time, the laser oscillation light is passed through alternate two calibration cells 1 and 2 in which gases to be dtected differing in concentration are sealed; and absorbed laser light power is detected by detector 6 to detect the current value when the difference in absorption power is maximum, and this current value is regarded as the value of the intermittent current for exciting the laser element. |
