| 摘要 |
PURPOSE:To eliminate the uneven concentration of the aerosol in the air as well as the effect of the time change, by using the position of observation of only one system and radiating the infrared light of two wavelengths alternately in a time enough shorter than the changing time constant of the aerosol distribution in the air. CONSTITUTION:When the first pulse is applied to the pulse motor M from the double pulse generator DPG, the infrared light of the wavelength lambda1 is radiated along the optical path. With erasion of the first pulse, the radiation is stopped for the infrared light of the wavelength lambda1. Instead the infrared light of the wavelength lambda2 is radiated. Accordingly, the light reception power to the infrared light of lambda1 and lambda2, i.e., the output voltage Va(t) show the same random change like the curve (n) even though the aerosol has some unevenness in the air. The differential voltage Vs(t) shown by the curves (o) and (p) obtained with reception of the scattered beams of the infrared light of lambda1 and lambda2 shows the absorption quantity of gas. Thus the concentration S of the subject gas can be obtained easily from the differential voltage. |
