An optical micro-projection system comprising the following components: at least one laser light source (200, 400, 402, 600); at least one movable mirror (102, 103, 203) for deviating light from said light source to allow generation of images on a projection surface (104, 301, 303, 306, 603); a self mixing module for measurement of the distance (604) between the projection source and a projection surface, said self mixing module comprising:—at least one photodiode (401, 601) for monitoring the light emission power of the laser light source;—an optical power variation counter for counting optical power variations (605); successive displacements of said mirror allowing the self mixing module providing successive projection distance measurements of a plurality of points of said projection surface. A projection method for optical micro-projection system and a distance measurement method are also provided.