Hybrid Cast-and-Mold Waveguide Combiner for Sink Mark Reduction
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Solution Overview
Problem
Conventional manufacturing processes for waveguide combiners, particularly those with high aspect ratios, result in sink marks and deformations due to uneven cooling and material stresses, leading to image quality issues such as scattering, refraction, and aberrations in augmented reality displays.
Innovation Solution
A hybrid casting and injection molding process is employed, dividing the manufacturing into separate stages to form waveguide structures in sections, using a two-part casting method to minimize sink marks and enhance precision, with optical coatings applied to facets for improved light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional injection molding is used to manufacture waveguide combiners with high aspect ratios, then productivity is improved through single-stage manufacturing, but manufacturing precision deteriorates due to sink marks and deformations
Solution Approach 1:
The manufacturing process is divided into two distinct stages: first, injection molding to create the base waveguide structure with facets; second, casting to form the optical layer. This segmentation allows each process to be optimized independently, eliminating the sink marks that occur when attempting to manufacture the entire component in a single injection molding step.
2Reliability
If high aspect ratio designs are used in waveguide combiners, then optical performance is improved through better light confinement, but manufacturing precision deteriorates due to uneven cooling and sink marks
Solution Approach 1:
The waveguide combiner is segmented into a base structure (injection molded) and an optical layer (cast). This allows the high aspect ratio facets to be formed in the base structure without suffering from sink marks, while the separate casting process ensures the optical layer has the required surface quality for optimal light confinement and transmission.
Solution Approach 2:
Different manufacturing processes are applied to different parts of the component: injection molding is used for the base structure where structural integrity and facet geometry are critical, while casting is used for the optical layer where surface quality and optical properties are paramount. This local quality approach ensures each region is manufactured with the most appropriate process.
3Device complexity
If single-stage injection molding is used, then device complexity is reduced through process simplification, but manufacturing precision deteriorates due to process limitations
Solution Approach 1:
The manufacturing process is segmented into two stages: injection molding for the base structure and casting for the optical layer. Although this increases process steps, each stage is independently optimized and well-understood, making the overall process manageable. The segmentation is necessary to achieve the required surface quality that cannot be obtained through single-stage injection molding.
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
The method reduces sink marks and deformations, enhancing optical clarity and image quality in augmented reality displays by minimizing reflections and distortions, thereby improving user experience.
Implementation Method 1
a transparent body that includes a first surface and a second surface
Implementation Method 2
one or more facets that extend from the first surface of the transparent body
Implementation Method 3
an optical coating that is disposed on a portion of the one or more facets
Data Source
AI summary
An optical component includes a waveguide combiner that has one or more optical components composed of a polymer and at least partially formed via a first casting process, a transparent body formed via a second casting process, the transparent body composed of a polymer and having a first working surface and an opposing second working surface. One or more optical components are disposed at a first surface of the transparent body. A thin film layer is disposed at least partially on one of the one or more optical components. A first layer of resin material overlays the one or more optical components and the first working surface of the transparent body.