| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a concentration measuring apparatus in which the influence of a disturbance is reduced to the minimum and by which the concentration of a sample fluid is measured with good accuracy. SOLUTION: The concentration measuring apparatus is provided with a sample cell 1 in which a sample fluid is housed, a reference cell 12 in which a reference medium is housed, a light source 13 which shines light at the respective cells 11, 12, a photodetector 24 which detects light which is transmitted through the respective cells 11, 12 and a chopper mechanism 25 by which the light irradiated from the light source 13 is changed into continuous pulsed light. A signal extraction part 30 extracts, from the detection signal of the photodetector 20, a signal component whose frequency is nearly identical to that of the continuous pulsed light. A concentration measuring part 40 computes the transmittance of the sample fluid on the basis of a signal component obtained from the intensity of the transmitted light of the sample cell 11 and on the basis of a signal component obtained from the intensity of the transmitted light of the reference cell 12. Since a disturbance such as indoor illumination light, radiant infrared rays or the like is removed in the extraction process of the signal component by the signal extraction part 30, the concentration of the sample fluid can be measured with good accuracy.</p> |
