With limited display luminance, the contrast of see-through head mounted display (HMD) systems can be degraded calamitously in the presence of high-luminance scenes, or bright ambients. Moreover, the visibility of a HMD is often impeded due to localized flares in the ambient. An ideal solution to the problem is an active ambient attenuator with adaptive optical density in the pixel level. This Phase I proposal addresses the design and fabrication of such an active ambient attenuator. The adaptive function of the proposed system is based on a nonlinear attenuation mechanism installed near the focus plane. A scene is first focused onto the focus plane near the adaptive attenuator. The adaptive attenuator is made to vary its optical density spatially in such a way that greater density is created in areas where more intense light impinges. Through such spatial filtering, the image is re-collimated for the viewer. With this system, the image of the ambient is altered to have a more uniform and suitable level of luminance for HMDs. In Phase I, a preliminary device will be made according to the described principles. A bench-top demonstration of the adaptive attenuation function will be performed.
Benefits: A successful implementation of the proposed adaptive optical attenuator will greatly improve the effectiveness of the HMD systems. Devices of this kind can also be used for eye protection for personnel in war or for patients of macular degeneration. Welders and other personnel exposed to sun glare and intense laser irradiation may also benifit from the protection of the proposed adaptive attenuator.
