Method for inspection of a substrate , the method comprising the following steps: - creating, based on at least two light beams originating from one and the same light source , a measurement volume at the intersection between said at least two light beams , the measurement volume containing interference fringes and being positioned so as to extend over or into the substrate , said substrate being in movement with respect to said measurement volume in a direction parallel to a main surface (S) of said substrate ; - acquiring a measurement signal representative of the light scattered by the substrate , as a function of the location of the measurement volume on said substrate ; - calculating at least one expected parameter, including at least one expected modulation frequency being an expected Doppler frequency, of an expected signal representative of the passage of a defect of said substrate through the measurement volume; - determining characteristic values representative of a frequency content of the measurement signal in a neighbourhood around the expected modulation frequency, so as to constitute a validated signal representative of the presence of defects ; the step of determining the characteristic values comprising the following steps: - modelling the expected signal according to a model function, in order to produce a modelled signal; - comparing the modelled signal to the measurement signal, including calculating a distance within the meaning of a Euclidian norm between the modelled signal and the measurement signal; and - analyzing said validated signal in order to locate and/or identify defects . - creating, based on at least two light beams originating from one and the same light source , a measurement volume at the intersection between said at least two light beams , the measurement volume containing interference fringes and being positioned so as to extend over or into the substrate , said substrate being in movement with respect to said measurement volume in a direction parallel to a main surface (S) of said substrate ; - acquiring a measurement signal representative of the light scattered by the substrate , as a function of the location of the measurement volume on said substrate ; - calculating at least one expected parameter, including at least one expected modulation frequency being an expected Doppler frequency, of an expected signal representative of the passage of a defect of said substrate through the measurement volume; - determining characteristic values representative of a frequency content of the measurement signal in a neighbourhood around the expected modulation frequency, so as to constitute a validated signal representative of the presence of defects ; the step of determining the characteristic values comprising the following steps: - modelling the expected signal according to a model function, in order to produce a modelled signal; - comparing the modelled signal to the measurement signal, including calculating a distance within the meaning of a Euclidian norm between the modelled signal and the measurement signal; and - modelling the expected signal according to a model function, in order to produce a modelled signal; - comparing the modelled signal to the measurement signal, including calculating a distance within the meaning of a Euclidian norm between the modelled signal and the measurement signal; and - analyzing said validated signal in order to locate and/or identify defects . <EOS>