Light that passes beyond the active reflective surface of an optical modulator is referred to as overfill. This overfill accounts for a considerable percentage of the light (and associated energy) that escapes use from those optical modulators used in optical projectors and optical displays. Overfill results from applying a two-dimensional illumination pattern of light that does not match the size and aspect ratio of a reflective surface of the optical modulator. Overfill is light that is directed at an active surface of the optical modulator but does not contact the active surface. The overfill light can scatter in an uncontrolled manner when interfering with the projected image or signal from the optical modulator, and can thereby degrade the quality of the projected image or signal. Any scattered light falling in the active reflective surface of the optical modulator will also get imaged on the screen, thereby degrading the contrast of the projected image.
As such, it is desired to be able to reduce overfill of the light that is applied across an optical modulator.