PROCEEDINGS ARTICLE | August 5, 2015
Proc. SPIE. 9618, 2015 International Conference on Optical Instruments and Technology: Optical Systems and Modern Optoelectronic Instruments
KEYWORDS: Mirrors, Eye, Holography, Waveguides, Reflectivity, Projection systems, Stray light analysis, Freeform optics, Stray light, Field emission displays
Nowadays, the waveguide has the advantages of small thickness and light weight so that it attracts more and more attention in the field of near-eye display. However, as a major problem, stray lights generated in the waveguide seriously degrade the display quality. In this paper, a geometrical waveguide with a beam-splitting mirror array (BSMA) is designed by using the non-sequential ray-tracing software LightTools, and great efforts are paid to study the causes and solutions of the stray light. With mass calculation and optimization based on the criterion of stray light/useful light ratio, an optimum design with the least amount of stray lights is found. To further eliminate the stray light, a novel structure that couples the rays into the waveguide is designed. The optimized waveguide has a FOV of 36° in the pupil-expanding direction of the waveguide, with stray light energy reduced to 1% over the useful light, the exit pupil diameter is 11.6mm at an eye relief of 20mm and the thickness is 2.4mm.
