Background composition concentration data representative of an actual background composition of a sample gas can be used to model absorption spectroscopy measurement data obtained for a gas sample and to correct an analysis of the absorption spectroscopy data (e.g. for structural interference and collisional broadening) based on the modeling.

Described is a method for quantifying the amount of optically interfering gas impurities in a gas detection system comprising a sample gas inlet, a reference gas inlet, a gas modulation valve, and an infrared absorption gas detector used for analysis of methane or natural gas, wherein the gas modulation valve alternatingly connects the sample gas inlet to the gas detector during a sample gas time period and the reference gas inlet to the gas detector during a reference gas time period. The method includes measuring an infrared absorption for at least two different sample gas concentrations in the gas detector achieved via respective different ratios from the sample gas time period and the reference gas time period, and comparing amplitudes of different measurement signals of the at least two different sample gas concentrations with calibration functions to assess an actual gas impurity concentration in the sampled gas.

A gas concentration-length quantification method may include: acquiring a multi-spectral image of detected radiance including a plurality of pixels using a multi-spectral optical gas imaging camera; estimating a background radiance for at least one of the pixels; calculating a gas concentration-length for the at least one of the pixels based on the detected radiance and the estimated background radiance; and triggering an alert when each alert condition in a list of alert conditions is satisfied. A multi-spectral configuration of the camera may include a reference band that is outside an absorption window of a target gas and an active band that includes at least a portion of the absorption window. Estimating the background radiance may include determining a model relating a detected radiance of the active band to a detected radiance of the reference band and using the model to estimate the background radiance for the active band.

The present invention is one adapted to correct the effect of a second gas component on a first gas component in real time even when the concentration of the second gas component as a coexistent component varies every moment, and includes: a first gas analysis part adapted to measure the concentration of the first gas component contained in sample gas; a second gas analysis part adapted to measure the concentration of the second gas component contained in the sample gas; a correction coefficient storage part adapted to store a correction coefficient for correcting the effect of the second gas component on the first gas component; and a concentration correction part adapted to correct the first gas component concentration on the basis of the correction coefficient, the second gas component concentration of calibration gas used for calibrating the first gas analysis part, and the second gas component concentration.

A method includes decomposing a training set to obtain a principal component matrix having a plurality of principal component vectors. The method also includes variably rejecting portions of a sample spectrum vector that do not correspond to a selected one of the plurality of principal component vectors by incrementally providing a coefficient indicative of the weighting of the selected principal component vector for selected sub-regions. A corrected spectrum vector can be obtained by excluding certain sub-regions of the sample spectrum vector and corresponding principal component vector, multiplying the sample spectrum vector with the principal component matrix for non-excluded sub-regions, providing a predicted interference vector, and subtracting the predicted interference vector from the sample spectrum vector.

Described is a method for quantifying the amount of optically interfering gas impurities in a gas detection system comprising a sample gas inlet, a reference gas inlet, a gas modulation valve, and an infrared absorption gas detector used for analysis of methane or natural gas, wherein the gas modulation valve alternatingly connects the sample gas inlet to the gas detector during a sample gas time period and the reference gas inlet to the gas detector during a reference gas time period. The method includes measuring an infrared absorption for at least two different sample gas concentrations in the gas detector achieved via respective different ratios from the sample gas time period and the reference gas time period, and comparing amplitudes of different measurement signals of the at least two different sample gas concentrations with calibration functions to assess an actual gas impurity concentration in the sampled gas.

In a leaked gas detection device and a leaked gas detection method according to the present invention, a gas cloud image area of a gas cloud formed with a leaked gas is extracted on the basis of an infrared image of a target area, a gas temperature of the gas cloud is acquired, a concentration-thickness product of the gas cloud is obtained, and a reliability degree that is an index representing the degree of reliability with respect to the obtained concentration-thickness product of the gas cloud is obtained on the basis of a background temperature in the gas cloud image area and the gas temperature of the gas cloud.

In a leaked gas detection device and a leaked gas detection method according to the present invention, a gas cloud image area of a gas cloud formed with a leaked gas is extracted on the basis of an infrared image of a target area, a gas temperature of the gas cloud is acquired, a concentration-thickness product of the gas cloud is obtained, and a reliability degree that is an index representing the degree of reliability with respect to the obtained concentration-thickness product of the gas cloud is obtained on the basis of a background temperature in the gas cloud image area and the gas temperature of the gas cloud.

A method includes decomposing a training set to obtain a principal component matrix having a plurality of principal component vectors. The method also includes variably rejecting portions of a sample spectrum vector that do not correspond to a selected one of the plurality of principal component vectors by incrementally providing a coefficient indicative of the weighting of the selected principal component vector for selected sub-regions. A corrected spectrum vector can be obtained by excluding certain sub-regions of the sample spectrum vector and corresponding principal component vector, multiplying the sample spectrum vector with the principal component matrix for non-excluded sub-regions, providing a predicted interference vector, and subtracting the predicted interference vector from the sample spectrum vector.

A spectral imaging system configured to obtain spectral measurements in a plurality of spectral regions is described herein. The spectral imaging system comprises at least one optical detecting unit having a spectral response corresponding to a plurality of absorption peaks of a target chemical species. In an embodiment, the optical detecting unit may comprise an optical detector array, and one or more optical filters configured to selectively pass light in a spectral range, wherein a convolution of the responsivity of the optical detector array and the transmission spectrum of the one or more optical filters has a first peak in mid-wave infrared spectral region between 3-4 microns corresponding to a first absorption peak of methane and a second peak in a long-wave infrared spectral region between 6-8 microns corresponding to a second absorption peak of methane.