Augmented reality display with high eyebox uniformity over the full field of view based on a random mask grating.

Ensuring uniform illuminance in waveguide-based augmented reality (AR) display devices is crucial for providing an immersive and comfortable visual experience. However, there is a lack of a straightforward and efficient design method available to achieve illuminance uniformity over the full field of view. To address this issue, we propose a novel design that utilizes random mask gratings (RMGs) as the folding grating and the out-coupling grating. Unlike traditional approaches that modify the grating structure, we control the diffraction efficiency distribution by adjusting the filling factor of the mask while keeping the grating structure unchanged in one RMG. The grating structures are designed and optimized based on rigorous coupled wave analysis and particle swarm optimization. The feasibility of our method is verified by the simulation results in Lighttools. In the FOV range of 20°×15°, the eyebox uniformities of all fields are greater than 0.78, which can provide a good visual experience for users.

Hybrid waveguide based augmented reality display system with extra large field of view and 2D exit pupil expansion.

For a waveguide display device, the field of view (FOV) is a key parameter for evaluating its optical performance. To address this issue, we propose a hybrid waveguide system, which is composed of two projectors, two in-couplers, two half-mirror arrays and an out-coupler. We use two projectors to generate the left and right parts of the output image separately, which can increase the upper limit of the FOV significantly. Unlike conventional waveguide-based system, we use half-mirror arrays instead of folding gratings to realize 2D exit pupil expansion. By doing so, the total internal reflection condition can always be met during the pupil expansion process. To solve the difficulty in designing collimating optical system with large FOV, we propose a method of tilting the projection system. The hybrid waveguide system can realize a FOV of 88°(H) × 53°(V).