Method for characterization of a light beam comprising the following steps: - separation of the light beam by means of a separator optic (Os, SR) into a first sub-beam and a second sub-beam, the first sub-beam taking a first optical path and the second sub-beam taking a second optical path; - propagation of the first sub-beam over a first optic and of the second sub-beam over a second optic, the first optic having a first radius of curvature so that the first sub-beam on leaving the first optic, referred to as "reference beam (Fref)", has wave fronts of a first type, the second optic having a second radius of curvature different from the first radius of curvature so that the second sub-beam on leaving the second optic, referred to as "characterized beam (Fear)", has wave fronts of a second type different from the first type, the first sub-beam having a non-homogeneous electromagnetic field over the entire surface of the first optic, said first and second optics (O1, O2) being, thanks to a control means (Pz), respectively arranged in the first and second optical paths (C1, C2) so that the reference beam (Fref) and the characterized beam (Fcar), are separated by a time delay τ; - recombination of the reference beam (Fref) and the characterized beam (Fcar) by means of a recombiner optic (Or, SR) in such a way that the beams spatially interfere and form a two-dimensional interference pattern, the two-dimensional interference pattern extending along a first plane; - measurement of the frequency spectrum (Spe) of at least one part of the two-dimensional interference pattern by means of a measuring system (SM3, SM4), the measuring system (SM3, SM4) comprising a spectrometer having an inlet slit (Fe) extending along a first spatial direction (x) of the first plane; - calculation of the Fourier transform in the time domain of at least one spatial point of the frequency spectrum (Spe), said Fourier transform in the time domain having a time central peak (tc) and first and second time side peaks (tl1, tl2); - calculation of the Fourier transform in the frequency domain (TFT') by means of a calculator for one of said first and second time side peaks (tl1, tl2); - calculation, by means of the calculator, of the spectral amplitude A R (ω), referred to as "relative spectral amplitude", and the spatial-spectral phase φ R (x,y,ω), referred to as "relative spatial-spectral phase", for said Fourier transform in the frequency domain (TFT'). - separation of the light beam by means of a separator optic (Os, SR) into a first sub-beam and a second sub-beam, the first sub-beam taking a first optical path and the second sub-beam taking a second optical path; - propagation of the first sub-beam over a first optic and of the second sub-beam over a second optic, the first optic having a first radius of curvature so that the first sub-beam on leaving the first optic, referred to as "reference beam (Fref)", has wave fronts of a first type, the second optic having a second radius of curvature different from the first radius of curvature so that the second sub-beam on leaving the second optic, referred to as "characterized beam (Fear)", has wave fronts of a second type different from the first type, the first sub-beam having a non-homogeneous electromagnetic field over the entire surface of the first optic, said first and second optics (O1, O2) being, thanks to a control means (Pz), respectively arranged in the first and second optical paths (C1, C2) so that the reference beam (Fref) and the characterized beam (Fcar), are separated by a time delay τ; - recombination of the reference beam (Fref) and the characterized beam (Fcar) by means of a recombiner optic (Or, SR) in such a way that the beams spatially interfere and form a two-dimensional interference pattern, the two-dimensional interference pattern extending along a first plane; - measurement of the frequency spectrum (Spe) of at least one part of the two-dimensional interference pattern by means of a measuring system (SM3, SM4), the measuring system (SM3, SM4) comprising a spectrometer having an inlet slit (Fe) extending along a first spatial direction (x) of the first plane; - calculation of the Fourier transform in the time domain of at least one spatial point of the frequency spectrum (Spe), said Fourier transform in the time domain having a time central peak (tc) and first and second time side peaks (tl1, tl2); - calculation of the Fourier transform in the frequency domain (TFT') by means of a calculator for one of said first and second time side peaks (tl1, tl2); - calculation, by means of the calculator, of the spectral amplitude A R (ω), referred to as "relative spectral amplitude", and the spatial-spectral phase φ R (x,y,ω), referred to as "relative spatial-spectral phase", for said Fourier transform in the frequency domain (TFT').