Polymeric Optical Layers for HMD Waveguides Without Delamination
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Solution Overview
Problem
The addition of optical layers to waveguides in head-mounted displays (HMDs) increases density, weight, and total thickness variation, and poses manufacturing challenges such as adherence issues and delamination during processing, preventing their widespread use.
Innovation Solution
The use of polymeric optical layers with a thiol-containing polymer, formed from a monomer mixture of thiol-containing compounds like 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol and isocyanates like m-xylylene diisocyanate, which can be applied to waveguides with a refractive index gradient or discrete layers to enhance optical efficiency without significant weight or manufacturability issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If optical layers are added to waveguides to improve optical efficiency, then eyebox efficiency is improved, but density, weight, and total thickness variation increase
Solution Approach 1:
The patent changes the material parameters by using polymeric optical layers with specific refractive indices (1.4-1.7) and optical properties (absorption ≤0.02 cm⁻¹, BSDF ≤0.001 sr⁻¹) that optimize eyebox efficiency while minimizing weight and thickness compared to traditional optical materials
Solution Approach 2:
The patent employs composite polymeric materials containing thiol-containing compounds and isocyanates that combine desirable optical properties with low density and weight, creating an optimized material system for optical layers in waveguides
2Illumination intensity
If optical layers are applied to waveguides to enhance optical performance, then optical efficiency is improved, but adherence issues and delamination occur during processing
Solution Approach 1:
The patent modifies the chemical and physical parameters of the optical layer material, using polymeric compounds with specific molecular structures (thiol-containing compounds reacting with isocyanates) that provide both optimal optical properties and superior adhesion to waveguide substrates, preventing delamination during processing
Solution Approach 2:
The patent uses the polymeric optical layer material itself as an intermediary that bonds the waveguide substrate to the optical functionality, with the thiol-isocyanate polymer system providing both adhesion and optical performance in a single integrated layer
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 polymeric optical layers improve eyebox efficiency by 2-5 times, maintain low optical loss and scatter, and withstand curing processes, ensuring minimal delamination and adherence, thus enhancing the optical performance of waveguides without increasing weight or production costs.
Implementation Method 1
a polymeric optical layer... formed from a monomer mixture including a thiol-containing compound and an isocyanate
Implementation Method 2
the thiol-containing polymer may be formed from a monomer mixture including a thiol-containing compound and an isocyanate
Implementation Method 3
The polymeric optical layer may include a varying index optical layer having a refractive index gradient across a thickness of the polymeric optical layer
Data Source
AI summary
The present disclosure relates to systems and methods of making polymeric optical layers for optical layering applications. In an aspect, a waveguide device for a head mounted display is provided. The waveguide device may include a waveguide die having a first refractive index range and a polymeric optical layer. The polymeric optical layer may include a second refractive index range that is different from the first refractive index range and a thiol-containing polymer. For example, the thiol-containing polymer may include thiourethane. In some embodiments, the thiol-containing polymer may be formed from a monomer mixture including a thiol-containing compound and an isocyanate. For example, the thiol-containing compound may include 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol (MDTODT) and/or the isocyanate may include m-xylylene diisocyanate (XDI). In some embodiments, the monomer mixture may include a second thiol-containing compound, such as, for example, 1,3-benzene dithiol (1,3-BDT).