Metasurface Overcoat Layout With Equal Gaps for Uniform Refraction

The patent applies local quality by varying the pitch between adjacent pillars based on their position in the array. Specifically, pillars are arranged with different spacing intervals - for example, first pillars may have pitch P1 while second pillars have pitch P2, where P1 ≠ P2. This local variation in pitch compensates for the curvature of the substrate, ensuring that the overcoat extends uniformly down the sidewalls of all pillars despite the curved deposition process, thereby achieving consistent refraction indices across the metasurface.

The patent inverts the conventional approach by not accepting variable gap sizes as a necessary consequence of equal pitch. Instead, it reverses the logic: rather than allowing gaps to vary with equal pitch, it implements variable pitch to achieve uniform gaps. This inversion of the cause-effect relationship - making pitch variable rather than gap variable - resolves the contradiction by simultaneously achieving manufacturing feasibility and optical performance consistency.

The patent applies parameter changes by modifying the pitch parameter across different regions of the metasurface. Instead of maintaining a constant pitch value throughout, the pitch is varied as a function of position - for example, increasing or decreasing pitch in specific zones to compensate for overcoat extension variations. This parameter modification eliminates the harmful optical effects caused by inconsistent refraction indices while preserving the overall structural uniformity of the metasurface array.