Waveguide Display Gratings with Continuous Phase Shifting

The patent applies local quality by varying the pitch of the surface relief grating continuously across different regions of the waveguide. Each local region has a specific pitch value that changes according to a continuous function, creating locally optimized diffraction that prevents coherent light path formation throughout the entire waveguide structure.

The patent implements parameter changes by continuously varying the grating pitch parameter across the waveguide. The pitch follows a continuous function (such as linear, quadratic, or higher-order polynomial) rather than remaining constant, which fundamentally changes the diffraction characteristics and eliminates the formation of coherent light paths that cause destructive interference.

The patent applies curvature by using continuous functions to define the pitch variation across the grating. Instead of abrupt step changes, the pitch transitions smoothly following curved mathematical functions (linear, quadratic, cubic, etc.), which eliminates sharp boundaries and prevents the formation of smear artifacts while remaining manufacturable with appropriate fabrication techniques.

The patent ensures continuity of useful action by implementing a continuous pitch function across the entire grating area. The pitch varies continuously without discontinuities or sharp transitions, maintaining smooth optical action throughout the waveguide and preventing artifact formation while allowing for practical manufacturing through techniques like grayscale lithography or controlled etching.