desired and maintaining the desired beam angles with respect to the platen containing the photosensitive material since a great deal of video information can be expressed through a substantial number of angle variations and beam intensities it is necessary that beam angles be regulated within narrow constraints this is done in the embodiment of fig9 through the use of an auxiliary beam following the path of the main beam and offset therefrom by a small angle as in the previous embodiments a computer 4 controlled by mouse 8 and a keyboard 7 controls the entire system a laser 1 such as a helium cadmium hecd laser generates a beam which is controlled by a birefringent shutter 2 this shutter is controlled by a driver 51 which in turn is controlled by computer 4 a beam from laser 1 is timed by shutter 2 to pass through beam profiler 57 used to control pixel size pixel shape and cross section the beam passes through an opening in the mirror 22 the beam is then split in beam splitter 60 into two beams a and b as illustrated beam a is reflected from mirror arrangement 61 which is constituted by two mirrors one deflecting on an x axis and one on.