Method for determining a set of physical parameters of a sample, comprising the steps of: - A Retrieving a measured sample temporal trace Es(t), the measured sample temporal trace Es(t) having been obtained by Time Domain Spectroscopy, by illuminating a sample by an excitation beam periodically emitting electromagnetic pulses with a period T and presenting a comb frequencies, and detecting an electromagnetic field coming from the sample as a function of time by a coherent detection, a time duration on which the sample temporal trace is measured being tmax, with tmax<T, - B retrieving a measured reference temporal trace Eref(t), the measured reference temporal trace Eref(t) having been obtained by illumination and detection in the same conditions than in step A but without the presence of the sample, - C determining a widened reference temporal trace, called ErefO(t), extending on the period T and obtained by affecting a zero value to instants for which no measurement have been performed, and determining a discrete Fourier transform Ẽ ref 0 (ω) of the widened reference temporal trace calculated on a time window equal to T, - D determining a modeling of an impulse response of the sample in the frequency domain, depending on the set of physical parameters (pi), called sample frequency model Ẽ model { p i}( ω), from the Fourier Transform of the widened reference temporal trace Ẽ ref 0 ( ω) and a physical behavior model of the sample, - E applying an optimization algorithm on the set of physical parameters (pi) comprising the sub steps of: - E1 initializing physical parameters (pi), - realizing iteratively the sub steps of: - E2 calculating an inverse discrete Fourier transform of the sample frequency model Ẽ model { p i}( ω), called estimated sample temporal trace E est { p i}( t), - E3 calculating an error function (ε er {pi}) from the difference between the measured sample temporal trace Es(t) and the estimated temporal trace Eest(t), until obtaining a set of values (pi opt) of physical parameters minimizing said error function. - A Retrieving a measured sample temporal trace Es(t), the measured sample temporal trace Es(t) having been obtained by Time Domain Spectroscopy, by illuminating a sample by an excitation beam periodically emitting electromagnetic pulses with a period T and presenting a comb frequencies, and detecting an electromagnetic field coming from the sample as a function of time by a coherent detection, a time duration on which the sample temporal trace is measured being tmax, with tmax<T, - B retrieving a measured reference temporal trace Eref(t), the measured reference temporal trace Eref(t) having been obtained by illumination and detection in the same conditions than in step A but without the presence of the sample, - C determining a widened reference temporal trace, called ErefO(t), extending on the period T and obtained by affecting a zero value to instants for which no measurement have been performed, and determining a discrete Fourier transform Ẽ ref 0 (ω) of the widened reference temporal trace calculated on a time window equal to T, - D determining a modeling of an impulse response of the sample in the frequency domain, depending on the set of physical parameters (pi), called sample frequency model Ẽ model { p i}( ω), from the Fourier Transform of the widened reference temporal trace Ẽ ref 0 ( ω) and a physical behavior model of the sample, - E applying an optimization algorithm on the set of physical parameters (pi) comprising the sub steps of: - E1 initializing physical parameters (pi), - realizing iteratively the sub steps of: - E2 calculating an inverse discrete Fourier transform of the sample frequency model Ẽ model { p i}( ω), called estimated sample temporal trace E est { p i}( t), - E3 calculating an error function (ε er {pi}) from the difference between the measured sample temporal trace Es(t) and the estimated temporal trace Eest(t), until obtaining a set of values (pi opt) of physical parameters minimizing said error function. - E1 initializing physical parameters (pi), - realizing iteratively the sub steps of: - E2 calculating an inverse discrete Fourier transform of the sample frequency model Ẽ model { p i}( ω), called estimated sample temporal trace E est { p i}( t), - E3 calculating an error function (ε er {pi}) from the difference between the measured sample temporal trace Es(t) and the estimated temporal trace Eest(t), until obtaining a set of values (pi opt) of physical parameters minimizing said error function. - E2 calculating an inverse discrete Fourier transform of the sample frequency model Ẽ model { p i}( ω), called estimated sample temporal trace E est { p i}( t), - E3 calculating an error function (ε er {pi}) from the difference between the measured sample temporal trace Es(t) and the estimated temporal trace Eest(t), until obtaining a set of values (pi opt) of physical parameters minimizing said error function.