Proceedings Article | 13 March 2024
KEYWORDS: Waveguides, Glasses, Visualization, Optical components, Design, Digital Light Processing, Eyewear, RGB color model, Image processing, Beam divergence
We present the design, implementation, and verification of high-resolution, diffraction-based augmented reality glasses for assisting persons with visual impairments. Existing systems, both commercially available and under development, provide needed functionality but present problems in terms of weight, size, and bulkiness that can detract from their usefulness. The system described herein addresses these issues while maintaining the capabilities of the other systems. The display component of the glasses employs a single waveguide and dispersion-compensating diffractive elements to maintain image integrity for the viewer while minimizing the size and weight of the overall system. Extensive MATLAB simulation provided precise control over the optical properties of the in-coupling, beam-expansion, and out-coupling optical components. Component parameters were varied systematically, and the performance was evaluated. A conventional lens, 31.9° prism, 2.2 mm waveguide thickness, and two linear diffractive gratings, with appropriate component separation, produced maximum displacement of 0.26 µm, maximum angular difference of 30.76 microdegrees, and output divergence of 12.2°. The output coupler design increased the viewing angle from the original 3.6° to a final 19.7°. Design elements were fabricated and performance of all elements matched well with simulation results. A prototype was constructed and evaluations are ongoing. Small size of all elements, especially the waveguide, allow potential integration into standard eyewear form factors. Although the original design addressed an RGB system, a monochromatic version would further reduce bulkiness and increase wearability while still addressing patient needs. Functions including image configuration, intensity, and magnification control provide utility needed for a variety of visual impairments.
