JPS6473239A - Gas concentration measurement for laser type gas sensor - Google Patents

Abstract

PURPOSE:To enable accurate measurement of the concentration of a gas to be measured as desired, by measuring spectra separately beforehand for a wavelength area of overlapping spectra to calculate a matrix of correction factors, which is multiplied by a matrix of actually measured values. CONSTITUTION:A laser light from a laser light source 15 is transmitted through a gas 16 to be measured to be incident on a photo detector 17 and converted into an electrical signal to undergo a density measurement processing for a gas being measured. A calculation means 18 determines a ratio between a known density of gas and a signal level in (n) wavelength areas where spectra of (n) types of gases overlap one another separately obtained by spectral measurement of the (n) different types of gas in terms of a known density of gas in the form of a matrix of (n) lines X (n) columns and an inverse matrix thereof is calculated to determine correction factors separately, which are stored with a memory means 19 beforehand. A calculation means 20 performs multiplication between a spectral measured value matrix based on the laser light transmitted through an atmosphere where more than one of the (n) types of gas are mixed and a matrix stored in the memory means 19.