Diffractive Optical Element Layout Merging to Reduce Edge Roughness

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Solution Overview

Problem

Existing methods for producing diffractive optical elements (DOEs) face challenges in efficiently reducing line edge roughness and computational complexity, particularly when dealing with small pixel sizes, which can lead to optical scattering and increased production costs.

Innovation Solution

A method involving the approximation of pixel layout designs by replacing zig-zag contours with straight lines and merging clusters of pixels to reduce the number of edges and corners, resulting in a modified pixel layout that requires less computational power and memory, and facilitates the fabrication of a master tool with improved optical performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional pixel layout designs with regular polygons are used, then the optical elements can be systematically fabricated, but line edge roughness increases and optical scattering occurs

Engineering Contradiction:
Improveline edge roughnessVSAvoidoptical scattering
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent merges multiple small pixel edges into fewer, longer straight line segments. By combining adjacent pixels with the same edge orientation into single continuous edges, the total number of edges is reduced, which minimizes line edge roughness and consequently reduces optical scattering in the diffractive optical elements.

Inventive Principle:
Principle #5Merging (Combining)

2Measurement precision

If detailed pixel layouts with many edges and corners are used, then optical design precision is maintained, but computational complexity and memory requirements increase

Engineering Contradiction:
Improveoptical design precisionVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent reduces computational complexity by merging adjacent pixels into larger super-pixels or by representing multiple pixel edges as single continuous edge segments. This consolidation maintains the essential optical design features while significantly reducing the number of geometric elements that need to be processed computationally.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts and removes redundant corner points and duplicate edge segments from the pixel layout. By eliminating these unnecessary geometric features that do not contribute to the optical function, the computational burden is reduced while preserving the critical optical design precision.

Inventive Principle:
Principle #2Taking out (Extraction)

3Manufacturing precision

If many small pixels are used to achieve fine optical control, then optical performance is improved, but the formation of pointy tips increases and production difficulty rises

Engineering Contradiction:
Improveoptical performanceVSAvoidproduction difficulty
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent combines multiple small pixels into larger composite structures with fewer, longer edges. This merging process eliminates the formation of pointy tips at pixel corners while maintaining fine optical control through the precise positioning and orientation of the merged edge segments.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP4208744B1Diffractive optical elements and master tools for producing the diffractive optical elements
Publication Date: 2025.07.02 NIL TECH APS (DK)
  • EP4208744B1 patent drawingFigure 1A~1C
  • EP4208744B1 patent drawingFigure 2A~2D
  • EP4208744B1 patent drawingFigure 3A~3B

AI summary

The present disclosure describes diffractive optical elements (DOEs) and master tools for producing the DOEs. In one aspect, the disclosure describes a method that includes modifying a first pixel layout design for diffractive optical elements to obtain a modified pixel layout design. The first pixel layout design comprises pixels, each of which has a shape of a regular polygon (e.g., a rectangular shape). Modifying the first pixel layout design includes approximating a shape contour of a cluster of pixels in the first pixel layout design by a single polygon that reduces a total number of edges relative to the shape contour of the cluster of pixels in the first pixel layout design. The method also includes using the modified pixel layout design to form a master tool for production of the diffractive optical elements.