The method comprises: detecting the positions (uo, vo) and (u1, v1) of said photonic beam (L) according to the coordinate axes X, Y on a first and second plane XY, which cut an optical axis X at a first and second point, respectively; comparing the results of said positional detections (uo, vo) and (u1, v1), and: if there are discrepancies which lie outside the margin of error (p), adjusting the angle of the photonic beam (L) according to the angle α and/or the angle β in order to overcome said discrepancies; or if there are no discrepancies which lie outside said margin of error (p), considering the angle of said photonic beam (L) as being properly adjusted. The system is adapted to implement the method set out by the invention.