digital cinema where many high power lasers are required plastics may be impractical for use with light directing prism 30 since the heat buildup from even small level of optical absorption could ultimately damage the material and degrade transmission in this case glass would be preferred again stress birefringence could be a problem for polarization based projectors in this case glass with low stress coefficient of birefringence such as sf57 could be used another option would be to use a very low absorption optical glass such as fused silica to prevent heat up of the material and therefore keep the birefringence from occurring these types of materials may not be conducive to creating a molded glass component thus requiring conventional polishing and or assembly of multiple pieces to make up the completed prism where molding is desired a slow mold process would be preferred and annealing is desirable to reduce any inherent stress a clean up polarizer may be desired or necessary to remove any rotated polarization states that might develop from any residual birefringence this is primarily a trade off of efficiency component cost and required polarization purity embodiments of the present invention can be useful for shaping the aspect ratio of the light source so that it suits the aspect ratio of the spatial light modulator that is used embodiments of the present invention can be used with light guides 52 of different dimensions allowing the light guide to be not only flexible but also shaped with substantially the same aspect ratio to that of the modulator for digital cinema this ratio would be approximately 1 9 1 an alternate embodiment.