a method and a system for analyzing the wavefront of a light beam , wherein a diffraction grating is arranged in a plane perpendicular to the light beam to be analyzed and optically conjugated to the analysis plane . different emerging beams of the grating interfere to generate an image having deformations linked to the gradients of the wavefront to be analyzed . the method is characterized in that the grating carries out the multiplication of an intensity function which is implemented by a two - dimensional grating with hexagonal meshing of surface s transmitting the light of the beam to be analyzed into plural emerging beams arranged in a hexagonal meshing , by an phase function which is implemented by a two - dimensional grating with hexagonal meshing of surface 3 s which introduces a phase shift close to 2π / 3 between two adjacent secondary beams .