Microsoft Corporation
Variable attenuation of an illumination source

Abstract:

Variable attenuation of an illumination source is provided by an aperture (i.e., an opening in a structure through which light passes) that is sandwiched between two tunable lenses that are configured to apply varying amounts of optical power. A controller operates the first tunable lens to apply optical power to the light to be divergent at the aperture structure so that a portion of the light is clipped. Varying the applied optical power at the first tunable lens can increase or decrease divergence at the aperture structure to thereby increase or decrease clipping and the attenuation of the light. The controller operates the second tunable lens to compensate for changes in light state at the first tunable lens by applying opposite optical power so that collimated light from the illumination source which enters the first tunable lens may exit the second tunable lens in the same collimated state.