Diffractive Grating Layout for Uniform AR Display Efficiency
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Solution Overview
Problem
Existing diffractive optical structures face challenges in achieving high diffraction efficiency and uniformity due to the complexity and cost associated with modulating one-dimensional gratings through parameters like linewidth and sidewall angle, limiting their effectiveness in augmented reality applications.
Innovation Solution
A specially designed grating structure with a two-dimensional layout that modulates diffraction efficiency by adjusting parameters such as period and linewidth in one dimension, while maintaining one-dimensional diffraction characteristics, thereby reducing process complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional one-dimensional gratings modulate diffraction efficiency by adjusting linewidth, depth, and sidewall angle, then diffraction efficiency can be controlled, but process complexity and cost increase significantly
Solution Approach 1:
The patent transitions from traditional one-dimensional grating modulation (adjusting linewidth, depth, sidewall angle in a single dimension) to a two-dimensional grating structure where diffraction efficiency is modulated by adjusting the period in the second direction. This dimensional change simplifies the manufacturing process while maintaining effective diffraction efficiency control, as the period adjustment can be achieved through standard lithography processes without complex deep-UV or multi-step fabrication.
2Manufacturing precision
If traditional one-dimensional gratings modulate diffraction efficiency by adjusting parameters, then diffraction efficiency can be controlled, but manufacturing cost increases
Solution Approach 1:
The patent changes the key parameter from grating depth and sidewall angle (which require complex deep-UV or multi-step fabrication) to the period of the grating structure in the second direction. This parameter change enables the use of standard lithography processes, significantly reducing manufacturing cost while maintaining precise control over diffraction efficiency through the period adjustment.
3Ease of manufacture
If traditional one-dimensional gratings are used, then existing processes can be maintained, but overall efficiency and uniformity are limited
Solution Approach 1:
The patent introduces a second dimension to the grating structure, creating a two-dimensional periodic arrangement. This enables simultaneous optimization of diffraction efficiency and uniformity across the entire field of view, as the second-direction period adjustment can compensate for variations in the first direction, achieving uniform brightness and color distribution without requiring complex deep-UV processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances overall optical efficiency and uniformity, improving brightness, color uniformity, and eyebox performance in augmented reality displays, while reducing production costs and process difficulty.
Implementation Method 1
gratings play a crucial role and are used to control the coupling, propagation, and out-coupling processes of the light
Implementation Method 2
utilize the total internal reflection of a transparent substrate to conduct images in a lossless manner to the wearer's eyes
Data Source
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AI summary
Embodiments of the present disclosure disclose a diffractive optical structure and an optical display device; wherein: the diffractive optical structure includes a substrate (1) and a grating structure (5) provided on the substrate (1), and the grating structure (5) includes a plurality of grating units (51) periodically arranged in a tiled pattern on a surface of the substrate (1) along both a first direction and a second direction; the grating structure (5) has a first grating modulation direction and a second grating modulation direction, the first grating modulation direction is perpendicular to the first direction, and a grating modulation amplitude in the first grating modulation direction is ΔE, ΔE = 1/(P3*sinθ), wherein P3 is a period of the grating structure (5) in the second direction, and θ is an included angle between the first direction and the second direction; light incident on the grating structure produces diffraction only in the first grating modulation direction and does not produce diffraction in the second grating modulation direction.