| 摘要 |
PURPOSE:To ensure a simple and accurate measurement without deciding the zero value, by sweeping the light frequency of the radiated luminous flux absorbed according to the gas concentration in the necessary range of change and recording the upper and lower peak values of the differentiated absorption curve. CONSTITUTION:The laser DL is driven by the driving power source 8 incorporating the oblique current generator 32 in addition to the DC power source 31 and the luminous flux amplitude modulating AC current generator 33 and produces the luminous flux by which the light frequency is swept in the necessary range of change. Accordingly, the scanning is given between the fixed points P11-P12 on the differentiated absorption curve, and then the recording including the upper and lower peak values Q21 and Q22, Q11 and Q12, and others is carried out in accordance with the gas concentration of the differentiated absorption curve by the recorder 5 via the photodetector D and the signal process system 21. As a result, the decision of zero value is eliminated with no optical system of the retro-reflector and others required. Thus the gas concentration is measured in an easy and assured way and in such simple constitution. |
