Quantum infrared sensor and quantum infrared gas concentration meter using the same

A quantum infrared gas concentration meter comprising:

• an infrared light source arranged at one end in a sample cell forming a flow passage of a measurement target gas;
• a quantum infrared sensor arranged at the other end in the sample cell,
• subtraction means for receiving sensor signals inputted via amplifiers amplifying sensor signals from the quantum infrared sensors and filters removing noise, and for subtracting signals from a circuit offset memory from the sensor signals to remove offsets, respectively;
• arithmetic operation means for computing, on the basis of signals from the subtraction means, a ratio of a transmission light amount in an absorption band of the measurement target gas to a transmission light amount in a wavelength range non-absorbable by the measurement target gas;
• addition means for adding, to a signal from the arithmetic operation means, an offset corresponding to a proportional coefficient from a gas offset memory because of usage of two wavelength ranges;
• and
• division means for performing division of a signal from the addition means by a light absorption coefficient of the gas from a gas constant memory and a constant of a gas passage length, wherein
• quantity of gas concentration is determined by use of the transmission light amount in the absorption band of the measurement target gas and the transmission light amount in the wavelength range non-absorbable by the measurement target gas;
• and
• wherein the quantum infrared sensor comprises:
• a plurality of quantum infrared sensor elements;
• a plurality of optical filters providing closer to an infrared light source than are the plurality of quantum infrared sensor elements, and selectively transmitting infrared rays in specific different wavelength ranges, respectively;
• and
• a holding frame holding at least the optical filters, and includes a plurality of through holes extending from the respective quantum infrared sensor elements toward the infrared light source, wherein the quantum infrared sensor elements and the filters are fitted into the through holes of the holding frame.