Hybrid Diffractive Waveguide Structures for AR Light Uniformity

The patent applies local quality by using different grating structures in different regions of the waveguide. Specifically, it employs a first grating structure with first parameters in a first region and a second grating structure with second parameters in a second region. This allows each region to be optimized for its specific function: one region prioritizes light outcoupling efficiency while another region prioritizes light spread uniformity, thereby resolving the contradiction between these two competing requirements.

The patent resolves this contradiction by implementing spatially varying grating structures where different regions have different properties optimized for their specific roles. The first grating structure in the first region is optimized for light spread uniformity, while the second grating structure in the second region is optimized for light output coupling efficiency. This local optimization approach allows both requirements to be satisfied simultaneously in different parts of the system.

The patent maintains low device complexity by using a single input coupler pupil while achieving wavelength uniformity through spatially varying grating structures. The first and second grating structures are positioned in different regions relative to the single input coupler, allowing each to handle specific wavelength ranges or functions. This approach achieves multi-wavelength uniformity without requiring multiple input couplers, thus maintaining simplicity while improving performance.