| 摘要 |
<p>PROBLEM TO BE SOLVED: To make the true concentration determinable with improved accuracy by compensating influence of a distrubing substance by measuring absorbance in two wave lengths, and simultaneously measuring intensity of the light of not passing through a measuring sample while being radiated from a light source. SOLUTION: A beam splitter 16 divides the main light 27 passing through measuring gas 40 into light beams 20, 21 to respectively detect the light having first/second wave lengths by first/second detecting means. A reference medium 40' is substituted for the measuring gas to be similarly measured, and these detecting output signals are inputted to a computer means 36 to calculate the concentration. A beam splitter 23 divides the light of a light source 11 into the main light 27 and the third light 28 to pass the main light 27 through the measuring gas 40 of a monitoring space 12, and a third detecting means 24 is arranged along the third light 28 to detect an ultraviolet ray having a first wave length. The fourth light 34 is divided from the third light 28 by a beam splitter 30, a fourth detecting means 31 is arranged along the fourth light 34 to measure the light having a second wave length, and a reference output signal is outputted to compensate a fluctuation in the light having the second wave length.</p> |
