The method enables a non-homogeneous diffusing object to be examined by illuminating the object with a continuous light by means of a light source. It previously comprises reconstruction of the three-dimensional spatial mapping of an attenuation variable representative of the diffusion and absorption non-homogeneities of the object, by resolving a diffusion equation .gradient..sup.2F({right arrow over (r)}.sub.S, {right arrow over (r)})-k'.sup.2({right arrow over (r)})F({right arrow over (r)}.sub.S, {right arrow over (r)})=A.sub.S.delta.({right arrow over (r)}-{right arrow over (r)}.sub.S). In the diffusion equation, A.sub.S is a constant, {right arrow over (r)} the spatial coordinate of any point of the mesh of a volume at least partially containing the object, and {right arrow over (r)}.sub.S the spatial coordinate of the light source. The transfer functions of an equation used for reconstructing the distribution of fluorophores integrate the attenuation variable reconstituted in this way.