Diffractive Head-Mounted Optical Systems for Use with Subtractive-Color Liquid-Crystal Displays

Head-mounted displays (HMDs) have been shown to assist the pilot in evaluating information from an increasing number of remote sources. With the development of subtractive color liquid crystal displays (SCLCD), color information can be used as an additional parameter to convey information to the pilot. Unfortunately, the image locations for the three primary colors of current SCLCDs are displaced longitudinally along the optical axis, making a light-weight, optical design difficult. Diffractive optical elements have the potential to provide chromatic aberration correction, weight reduction, and aberration correction necessary for a SCLCD HMD. During Phase I, we will analyze several concepts utilizing diffractive optics in color HMD systems. The designs will characterize combination of beamsplitters and visor/combiners, including a tilted, off-axis visor/combiner. These designs will demonstrate the light-weight optical and mechanical sub-systems required to implement the HMD display with a standard helmet shell. To demonstrate the color correction that can be obtained with diffractive elements, a fabricate a prototype system for a SCLCD, measure its performance, and compute the experimental results with design predictions. In Phase II we will optimize and fabricate the color HMD system that utilizes SCLCD technology.