Method for the reconstructive multi-spectral imaging of a primary source, using a fixed or moveable instrument, characterised in that it comprises: - measuring the intensity of the light, in the vicinity of a focal plane of an optic, coming from a secondary optical source obtained by acousto-optic diffraction of the light in an acousto-optic device originating from the primary optical source, - acquiring said measurements of the intensity of the light from said secondary optical source by means of an array of one or two-dimensional pixelated sensors located in the vicinity of said focal plane, - calibrating using a monochromatic primary source, consisting of measuring for each pixel (m), in the focal plane, the acoustic frequency fa corresponding to the wavelength of said monochromatic primary source and producing an acousto-optic diffraction at the point (m), - determining, by using this calibration and the a priori knowledge of the variation of the optical indices of the material constituting the acousto-optic device with the wavelength (λ), of the function f2(m,λ) supplying for any wavelength (λ) and any image point (m) the value of the acoustic frequency producing said acousto-optic diffraction of the wavelength (λ) at the pixel (m), - acquiring multi-spectral images by a combination of acquisitions of the aforesaid pixelated sensors, either for a series of distinct acoustic frequencies, or by a relative movement of the instrument in relation to the primary source or by a combination of series of said frequencies and of said movement, an intensity sought for each point of the primary source I M λ = Im f 1 M λ t, f 2 f 1 M λ t, λ being obtained from the intensity measured Im at the pixel m corresponding to the point of the primary source, from the knowledge of the aforesaid function f2(m,λ) and, for each acquisition, of the relation f1 between each point of the primary source and each pixel (m). - measuring the intensity of the light, in the vicinity of a focal plane of an optic, coming from a secondary optical source obtained by acousto-optic diffraction of the light in an acousto-optic device originating from the primary optical source, - acquiring said measurements of the intensity of the light from said secondary optical source by means of an array of one or two-dimensional pixelated sensors located in the vicinity of said focal plane, - calibrating using a monochromatic primary source, consisting of measuring for each pixel (m), in the focal plane, the acoustic frequency fa corresponding to the wavelength of said monochromatic primary source and producing an acousto-optic diffraction at the point (m), - determining, by using this calibration and the a priori knowledge of the variation of the optical indices of the material constituting the acousto-optic device with the wavelength (λ), of the function f2(m,λ) supplying for any wavelength (λ) and any image point (m) the value of the acoustic frequency producing said acousto-optic diffraction of the wavelength (λ) at the pixel (m), - acquiring multi-spectral images by a combination of acquisitions of the aforesaid pixelated sensors, either for a series of distinct acoustic frequencies, or by a relative movement of the instrument in relation to the primary source or by a combination of series of said frequencies and of said movement, an intensity sought for each point of the primary source I M λ = Im f 1 M λ t, f 2 f 1 M λ t, λ being obtained from the intensity measured Im at the pixel m corresponding to the point of the primary source, from the knowledge of the aforesaid function f2(m,λ) and, for each acquisition, of the relation f1 between each point of the primary source and each pixel (m).