8e56 and 8e75 the amount of exposure time required for the holographic plate is typically specified by the film manufacturer once exposed the holographic plate must be developed to produce the diffraction grating the procedures for this development are well known to persons of ordinary skill in the art by way of example however the plate may be developed by immersion in jd 2 sold by integraf for two minutes the plate is then washed for three minutes with distilled water thereafter the plate film is bleached using integraf bleach until it is clear and then washed for another three minutes with distilled water finally the film is air dried this may be accomplished with a hand held hair dryer computer generated holograms which may be utilized in the practice of the present invention are produced in accordance with the following general procedures initially the required hologram diffraction grating i e that required to produce the desired resultant j o profiled beam from a given incident gaussian profiled beam is calculated numerically via a computer using commercially available software second a computer controlled electron gun is utilized to etch 0 5 micron width lines into the holographic plate in accordance with the previously calculated pattern the result is a phase hologram which produces the desired j o profiled output beam when a particular gaussian profiled reference beam is incident on the plate with reference to fig5 a and b there is shown apparatus for effecting the conversion of a typical profile laser beam into a j.