Abstract: A method for optimizing values of n detection wavelengths of an optical gas sensor configured to detect n different gases is provided, including: a) calculating a value of a determinant of an absorptivity matrix ? whose coefficients represent spectral absorptivity of each of the n different gases at the n detection wavelengths, the calculating being repeated several times, each time modifying at least one of said n detection wavelengths so the values of said n detection wavelengths are comprised within a range of values for which the spectral absorptivity of at least one of the n different gases is non-zero; and b) determining the values of said n detection wavelengths for which the calculated value of the determinant of the absorptivity matrix ? corresponds to a maximum calculated value amongst a set of values calculated in step a).

Abstract: Method for optimising the values of n detection wavelengths of an optical gas sensor capable of carrying out detection of n different gases, comprising the implementation of the following steps: a) calculation of a value of a determinant of an absorptivity matrix ? whose coefficients represent the spectral absorptivity of each of the n gases at n detection wavelengths, step a) being repeated several times, each time modifying at least one of said n detection wavelengths and such that the values of said n detection wavelengths are comprised within a range of values for which the spectral absorptivity of at least one of the n gases is non-zero; b) determination of the values of said n detection wavelengths for which the value of the determinant of the absorptivity matrix ? corresponds to the maximum value amongst the set of previously calculated values.

Abstract: An optical reflection focusing device, including a grating including an alternation of first and second regions having different refraction indexes, the grating including a plurality of sub-gratings, each including a plurality of first regions aligned along a plane parallel to the mean plane of the grating, said device including structures such that, for a collimated incident coherent light beam orthogonal to the mean plane of the grating, the rays of the beam reach with a non-zero phase shift different sub-gratings of the device.

Abstract: An optical reflection focusing device, including a grating including an alternation of first and second regions having different refraction indexes, the grating including a plurality of sub-gratings, each including a plurality of first regions aligned along a plane parallel to the mean plane of the grating, said device including structures such that, for a collimated incident coherent light beam orthogonal to the mean plane of the grating, the rays of the beam reach with a non-zero phase shift different sub-gratings of the device.