Patent ID: 7872756

Claim:
A gas measuring apparatus comprising: an infrared detecting section that receives an infrared ray from a measurement area and outputs infrared spectrum data relating to the infrared ray; a variation detecting section that detects, by using the infrared spectrum data, a variation in intensity of the infrared ray, which is caused in the infrared ray that radiates from the measurement area and which is caused by a measuring object gas in the measurement area; a converting section that converts the infrared spectrum data to radiance temperature spectrum data which represent wavelengths in an infrared region and radiance temperatures at each wavelength; a background temperature detecting section that detects, as background temperature of the measuring object gas, a maximum radiance temperature from among radiance temperatures represented by the radiance temperature spectrum data; a gas temperature detecting section that detects the temperature of the measuring object gas by using the radiance temperature in a wavelength band included in the water vapor absorption band in the infrared region from among the radiance temperatures represented by the radiance temperature spectrum data; and a computing section that computes surface density of the measuring object gas on the basis of the variation in intensity of the infrared ray, the background temperature of the measuring object gas, and the temperature of the measuring object gas.