Graded Edge Diffractive Optical Elements for Misalignment Tolerance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional diffractive optical elements (DOEs) are sensitive to misalignment during manufacturing, leading to reduced optical resolution and vestibular discomfort in near eye display systems due to sharp boundaries and nanometer-level accuracy requirements that are difficult to achieve in volume production.
Innovation Solution
The implementation of graded profiles on the trailing and leading edges of DOEs, where the grating height smoothly decreases and increases respectively, reduces the sharp boundary between DOEs, increasing tolerance for manufacturing misalignment while maintaining optical resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sharp boundaries are used at the interface between upstream and downstream DOEs, then optical resolution can be maintained, but sensitivity to misalignment increases during manufacturing
Solution Approach 1:
The patent applies graded profiles to the DOE edges, where the grating height varies continuously from full height to shallow height (or zero) across a transition region. This parameter change in grating height creates a smooth transition that reduces sensitivity to misalignment while maintaining optical resolution, directly resolving the technical contradiction between these two parameters.
2Manufacturing precision
If graded profiles are applied to DOE edges, then manufacturing tolerance for gap height mismatch increases, but the structure becomes more complex
Solution Approach 1:
The graded profiles are applied locally only at the edges of the DOEs where the grating height transitions from full height to shallow height or zero. The bulk of the DOE maintains its standard periodic structure. This localized application of the graded profile increases manufacturing tolerance at critical interfaces while minimizing the overall structural complexity of the DOE.
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
This approach enhances manufacturing tolerance for gap height mismatch and maintains optical resolution, reducing the impact of misalignment and improving the functionality and user comfort of near eye display systems.
Implementation Method 1
Diffractive optical elements (DOEs) are optical elements with a periodic structure which are commonly utilized in applications ranging from bio-technology, material processing, sensing, and testing to technical optics and optical metrology.
Implementation Method 2
FIG 2 shows propagation of light in a waveguide by total internal reflection
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
In an optical system that includes a waveguide with multiple diffractive optical elements (DOEs) incorporating diffraction gratings, light exiting a trailing edge of an upstream DOE enters a leading edge of a downstream DOE. One or more of the DOEs may include a leading and/or a trailing edge that have a graded profile. At a graded trailing edge of an upstream DOE, grating height smoothly decreases from full height to shallow height as a function of the proximity to the trailing edge. At a graded leading edge of the downstream DOE grating height smoothly increases from shallow height to full height as a function of distance away from the leading edge. By reducing a sharp boundary at the interface between the upstream and downstream DOEs, the graded profiles of the DOE edges enable optical resolution to be maintained decreasing sensitivity to misalignment between the DOEs that may occur during manufacturing.