Illumination in optical systems

Various embodiments involving structures and methods for illumination can be employed, for example, in projectors, head-mounted displays, helmet-mounted displays, back projection TVs, flat panel displays as well as other optical systems. Certain embodiments may include prism elements for illuminating, for example, a spatial light modulator (236). Light may be coupled to the prism in some cases using fiber optics (206) or lightpipes. The optical system may also include a diffuser (240) having scatter features arranged to scatter light appropriately to produce a desired luminance profile. Other embodiments are possible as well.