A method and a system to quantify gas in a thermal imaging device, said method comprising obtaining a gas-absorption-path-length image as a scene difference infrared image based on a gas infrared image and a scene background infrared image substantially depicting the same scene and generating a quantified scene difference infrared image based on said scene difference infrared image and a predefined gas-quantifying relation.

A method and a system to quantify gas in a thermal imaging device, said method comprising obtaining a gas-absorption-path-length image as a scene difference infrared image based on a gas infrared image and a scene background infrared image substantially depicting the same scene and generating a quantified scene difference infrared image based on said scene difference infrared image and a predefined gas-quantifying relation.

Systems, methods, and computer program products for infrared (IR) image operations are provided. An example imaging system includes a first IR imaging device configured to generate first IR image data and a second IR imaging device configured to generate second IR image data. The system further includes a computing device that receives the first IR image data from the first IR imaging device and receives the second IR image data from the second IR imaging device. The computing device further determines a first feature representing a position of a gas plume based upon the first IR image data and a second feature representing a position of the gas plume based upon the second IR image data and determines a disparity between the first and second features. The computing device further determines a distance between the imaging system and the gas plume based upon the determined disparity.

Systems, methods, and computer program products for infrared (IR) image operations are provided. An example imaging system includes a first IR imaging device configured to generate first IR image data and a second IR imaging device configured to generate second IR image data. The system further includes a computing device that receives the first IR image data from the first IR imaging device and receives the second IR image data from the second IR imaging device. The computing device further determines a first feature representing a position of a gas plume based upon the first IR image data and a second feature representing a position of the gas plume based upon the second IR image data and determines a disparity between the first and second features. The computing device further determines a distance between the imaging system and the gas plume based upon the determined disparity.

A method for detecting and identifying a remote gas, the method comprising the steps of: receiving a light wave associated with the remote gas; coupling the light wave into a single mode fibre; transmitting the light wave via the single mode fibre into a filter comprising a fibre-based tunable cavity; modulating the cavity length of the filter transmission window to cause a detected modulated signal that is proportional to the spectral feature; and processing the signal using a lock-in amplifier capable of low-pass filtering and out-of-frequency noise rejection.

An optical filtering device, in particular for remote gas detection, including a member comprising a tubular passage accommodating a plurality of reflective structures capable of reflecting infrared wavelengths, said structures being elongated along an axis of the tubular passage and arranged around the axis. The reflective structures comprise means of filtering by absorption of bands of different wavelengths located in the infrared spectral band.

An optical filtering device, in particular for remote gas detection, including a member comprising a tubular passage accommodating a plurality of reflective structures capable of reflecting infrared wavelengths, said structures being elongated along an axis of the tubular passage and arranged around the axis. The reflective structures comprise means of filtering by absorption of bands of different wavelengths located in the infrared spectral band.

A multi-channel gas sensor comprising a gas cell (101, 601), a light source (110, 210, 310, 410, 510, 610), a first interference filter (150, 250, 350, 450, 550, 650), a first detection unit (120, 220, 320, 420, 520, 620) and a second detection unit (130, 230, 330, 430, 530, 630). The light source (110, 210, 310, 410, 510, 610) is arranged to emit light radiation into the gas cell (101, 5 601). The first detection unit (120, 220, 320, 420, 520, 620) is arranged to detect light from the light source, that has propagated through at least a part of the gas cell (101, 601), and that has been transmitted through the first interference filter (150, 250, 350, 450, 550, 650). The second detection unit (130, 230, 330, 430, 530, 630) is arranged to be illuminated by light from the light source that has been reflected in the first interference filter (150, 250, 350, 450, 10 550, 650) and then has propagated through the gas cell (101, 601) before illuminating the second detection unit and to detect at least a second wavelength portion of said light that has been reflected in the first interference filter.

A multi-channel gas sensor comprising a gas cell (101, 601), a light source (110, 210, 310, 410, 510, 610), a first interference filter (150, 250, 350, 450, 550, 650), a first detection unit (120, 220, 320, 420, 520, 620) and a second detection unit (130, 230, 330, 430, 530, 630). The light source (110, 210, 310, 410, 510, 610) is arranged to emit light radiation into the gas cell (101, 5 601). The first detection unit (120, 220, 320, 420, 520, 620) is arranged to detect light from the light source, that has propagated through at least a part of the gas cell (101, 601), and that has been transmitted through the first interference filter (150, 250, 350, 450, 550, 650). The second detection unit (130, 230, 330, 430, 530, 630) is arranged to be illuminated by light from the light source that has been reflected in the first interference filter (150, 250, 350, 450, 10 550, 650) and then has propagated through the gas cell (101, 601) before illuminating the second detection unit and to detect at least a second wavelength portion of said light that has been reflected in the first interference filter.

In order to provide an absorbance analysis apparatus for DCR gas that can measure a concentration of a DCR gas by separating absorbance of the DCR gas alone even in a mixed gas consisting of the DCR gas and CO gas whose absorption spectrum overlaps each other, the absorbance analysis apparatus for DCR gas comprises a DCR filter 31 that is configured to transmit a light in a first wavenumber domain including an absorbance peak of the DCR gas, a CO filter 32 that is configured to transmit a light in a second wavenumber domain that is different from the first wavenumber domain, and a DCR gas volume calculator 4 that is configured to calculate volume of the DCR gas based on a first absorbance measured by the light transmitted through the DCR filter 31 and a second absorbance measured by the light transmitted through the CO filter 32.