A method is provided for inspecting the surface of an object such as a wafer having tridimensional structures, using a confocal chromatic device with a plurality of optical measurement channels and a chromatic lens allowing optical wavelengths of a broadband light source to be focused at different axial distances defining a chromatic measurement range. The method includes a step of obtaining an intensity information corresponding to the intensity of the light actually focused on an interface of the object within the chromatic measurement range at a plurality of measurement points on the object by measuring a total intensity over the full spectrum of the light collected by at least some of the optical measurement channels in a confocal configuration.