Patent Number: 
Section: claims

1. A method for extracting a primary diffuse radiation spectrum from a diffusion spectrum of diffuse radiation, according to a diffusion angle, coming from a material exposed to incident radiation through a surface, the method comprising:application of a spectral response function corresponding to a multiple diffuse radiation spectrum when a photon with a given energy belonging to the primary diffuse spectrum is detected,wherein the spectral response function comprises a correlation matrix (M) of which each value aij corresponds to a number of detected photons, with energy Ei, constituting the multiple diffuse radiation, when a photon of the primary diffuse spectrum is detected with energy Ej. 2. The method according to claim 1, wherein the spectral response function supplies a discretized spectrum over a finite number of energy ranges. 3. The method according to claim 1 further comprising an iterative process in which each step includes an estimation of the multiple diffusion spectrum to create an estimated multiple diffusion spectrum following a preceding estimation of the primary diffuse radiation spectrum and a new estimation of the primary diffuse radiation spectrum, by subtracting the estimated multiple diffusion spectrum from the diffusion spectrum, wherein the iterative process is continued until satisfaction of a convergence criterion related to successive estimated primary diffusion spectra. 4. The method according to claim 1, wherein the spectral response function comprises a result of interpolating a plurality of spectral response functions to monochromatic exposure of different materials for a given depth considering only the density of the different materials. 5. The method according to claim 1, wherein the spectral response function comprises a result of interpolating a plurality of spectral response functions to monochromatic exposure of the material for different depths. 6. The method according to claim 1, wherein the spectral response function is obtained beforehand by experimental acquisition of a response to monochromatic exposure of the material for a given depth. 7. The method according to claim 1 further comprising a preliminary estimation of a first estimated primary diffuse spectrum, carried out by multiplying a measured total diffusion spectrum by a multiplication coefficient dependent of the inspection depth. 8. The method according to claim 1, wherein the radiation comprises X rays. 9. A device for extracting a primary diffuse radiation spectrum from a diffusion spectrum of a diffuse radiation through a material to be analyzed, the device comprising:a source of incident radiation configured to irradiate a surface of the material;a detector configured to detect the radiation diffused by the material according to at least one preselected diffusion angle; andmeans for applying a spectral response function corresponding to a multiple diffuse radiation spectrum when a photon is detected with given energy belonging to the primary diffuse radiation spectrum, wherein the spectral response function comprises a correlation matrix (M) of which each value aij corresponds with a number of detected photons, with energy Ei, constituting the multiple diffuse radiation, when a photon of the primary diffuse radiation is detected with energy Ej. 10. The device according to claim 9, wherein the radiation source and the detector are both strongly collimated. 11. The device according to claim 9, wherein the detector resides in a same half-space as the radiation source opposite the irradiated surface of the material. 12. A device for spectrometry analysis comprising a device for extracting a spectrum of primary diffuse radiation according to claim 9. 13. A non-transitory computer readable media including a sequence of instructions that, when executed by a microprocessor, implement the method according to claim 1.