a method and device for measuring the speed of at least one object by doppler effect , whereby the light diffused by an object illuminated by a laser sheet is transmitted to a ccd video camera by spectral filtering means which are substantially tuned to the laser illumination frequency , means being provided to generate reference monochromatic luminous fluxes having frequencies which are different from the laser illumination frequency by fixed known amounts , and the reference luminous fluxes being transmitted to the ccd video camera .