808 in fig2 defining a patterned substrate 810 located between exposed areas 808 are photo resist islands 812 patterned substrate 810 is exposed to a light source such as ultraviolet light this ultraviolet light darkens the volume of photo resist layer 800 that is coextensive with exposed areas 808 being darkened i e become opaque to optical energy the volume of photosensitive layer 800 that are coextensive with photo resist islands 812 are not darkened by the ultraviolet light i e remaining transparent to optical energy thereafter photo resist islands 812 are removed using standard etch techniques leaving etched substrate 814 shown in fig2 etched substrate 814 has two arcuate regions 816 that are located in areas of the photosensitive layer 800 disposed adjacent to islands 812 shown in fig2 arcuate regions 816 of fig2 result from the difference in exposure time to the etch process of the differing regions of photosensitive layer 800 referring to fig2 and 22 a subsequent etch process is performed to form array 400 during this etch process the support is removed as well as nearly 50 of photosensitive layer 800 to form a very thin array array 400 is then placed in the apparatus 30 and the bulk holographic transform functions are recorded in the.