Photo-patternable Tin Oxide Sol-Gel Coatings for AR Refractive Index Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sol-gel materials for optical coatings in artificial reality systems face challenges in achieving high refractive index modulation and uniformity, especially at thicker coating thicknesses, which can lead to optical artifacts and reduced image quality.
Innovation Solution
A sol-gel material comprising a tin dichloride salt, an alcohol-containing solvent, and metal oxide nanoparticles, which can form a coating with a formula SnO(n)X(m) that varies in refractive index across regions due to selective photo-excitation followed by thermal annealing, allowing for controlled refractive index modulation and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If sol-gel materials are used for optical coatings in artificial reality systems, then transparent high refractive-index coatings can be manufactured, but achieving high refractive index modulation and uniformity at thicker coating thicknesses is difficult
Solution Approach 1:
The patent applies local quality by creating spatially varying refractive indices within the coating through controlled condensation. Different regions of the coating have different n:m ratios, with higher refractive indices in specific areas and lower refractive indices in other areas, enabling holographic optical elements with precise local optical properties while maintaining overall coating uniformity
Solution Approach 2:
The patent changes physical and chemical parameters during the sol-gel process, specifically controlling the condensation degree and n:m ratio through annealing conditions. By varying temperature, time, and atmospheric conditions during annealing, the refractive index can be precisely tuned across different regions of the coating, achieving both high refractive index modulation and uniformity
2Productivity
If selective photo-excitation followed by blanket thermal annealing is used to vary refractive index across regions, then high diffraction efficiency is achieved, but the process complexity increases
Solution Approach 1:
The patent applies preliminary action by first performing selective photo-excitation to create a latent image pattern, then following with blanket thermal annealing to develop the final refractive index modulation. The photo-excitation step prepares the material by creating spatially selective condensation nuclei, and the subsequent thermal annealing uniformly processes the entire coating to achieve the final holographic structure, simplifying the overall process while maintaining high diffraction efficiency
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 sol-gel material achieves refractive index values between 1.65 and 2.35 with minimal absorption in the visible spectrum, enabling high diffraction efficiency and reduced optical artifacts, even at thicker coating thicknesses.
Implementation Method 1
selective photo-excitation followed by blanket thermal annealing
Implementation Method 2
Upon depositing the solution and annealing the sol-gel, the precursor ligands and solvent may be removed to fully condense the extended network into an oxide or inorganic film
Implementation Method 3
the condensation process may result in densification and, potentially, crystallization
Data Source
AI summary
Techniques disclosed herein relate to photo-patternable latent-chemistry inorganic materials. An example of the photo-patternable latent-chemistry inorganic materials includes a sol-gel material comprising a solution containing a tin dichloride salt, at least one alcohol containing solvent, and optionally a photo-acid generator or photo-acid. The sol-gel material, upon selective photo-excitation (which forms a latent pattern with latent chemistry in the sol-gel material) and blanket thermal annealing, can form a coating having a formula SnO(n)X(m), where the n:m ratio and/or n-m values of the coating vary across regions of the coating, such that a refractive index of the coating varies across regions of the coating, without affecting the coating's transparency for visible light.