Multiplexed Image Light Guide With Split In-Coupling for Fewer Waveguides

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Solution Overview

Problem

Conventional Head-Mounted Displays (HMDs) require multiple waveguides for different wavelength ranges, increasing costs and potential for manufacturing defects, and overlapping out-coupling gratings add complexity.

Innovation Solution

A single image light guide with a split in-coupling diffractive optic and overlapping sets of diffractive features optimized for different wavelength ranges, introducing optical power to change focusing distances and enabling efficient virtual image formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If multiple waveguides are used for different wavelength ranges, then the virtual image quality is improved, but the manufacturing complexity and defect risk increase

Engineering Contradiction:

Improvevirtual image qualityVSAvoidnumber of waveguides

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple wavelength-specific waveguides into a single multiplexed waveguide structure. Different wavelength ranges (e.g., red, green, blue) that previously required separate waveguides are now transmitted through a single waveguide using wavelength-division multiplexing, reducing the number of components while maintaining image quality

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single waveguide is designed to perform multiple functions by simultaneously guiding different wavelength ranges through it. The waveguide structure is optimized to handle various wavelengths, making it a universal optical path that replaces multiple specialized waveguides

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Manufacturing precision

If overlapping out-coupling diffractive optic gratings are used to outcouple different wavelength ranges, then the virtual image formation is improved, but the optical system complexity increases

Engineering Contradiction:

Improvevirtual image formationVSAvoidoptical system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges multiple wavelength-specific out-coupling gratings into a single overlapping grating structure. The gratings for different wavelength ranges are superimposed on the same physical location, allowing simultaneous out-coupling of multiple wavelengths without requiring separate optical paths

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The solution transitions from spatial separation of wavelength-specific components to spectral separation within a shared spatial structure. By using wavelength-division multiplexing, the system exploits the spectral dimension to differentiate between wavelength ranges while sharing the same physical optical path

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If multiple waveguides are used for different wavelength ranges, then the virtual image quality is improved, but the cost increases

Engineering Contradiction:

Improvevirtual image qualityVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent combines multiple waveguides into a single multiplexed waveguide, reducing component count and assembly requirements. This consolidation directly lowers manufacturing costs while maintaining the ability to transmit multiple wavelength ranges with high image quality

Inventive Principle:

Principle #5Merging (Combining)

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 solution reduces the need for multiple waveguides, minimizing manufacturing defects and complexity while maintaining efficient virtual image presentation.

Implementation Method 1

collimated, relatively angularly encoded light beams from a polychromatic or monochromatic image projector source are coupled into an optically transparent planar waveguide by an input coupling optic, such as an in-coupling diffractive optic

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

the diffracted color image-bearing light can be directed back out of the planar waveguide by a similar output grating

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 3

the first and second set of diffractive features introduce an optical power to change a focusing distance of the first wavelength range and the second wavelength range of image-bearing light beams

Methodology Applied

Scientific EffectOptical power: Lens

Data Source

PatentUS20250306373A1Multiplexing image light guide with split input and optical power

Publication Date: 2025.10.02 VUZIX CORP

AI summary

An image light guide, including a substrate operable to propagate image-bearing light beams of a first wavelength range and a second wavelength range, an in-coupling diffractive optic including a first input region and a second input region, the first input region operable to couple image-bearing light of the first wavelength range into the image light guide and the second input region operable to couple image-bearing light of the second wavelength range into the image light guide, and an out-coupling diffractive optic including a first set of diffractive features and a second set of diffractive features, wherein the first set of diffractive features and the second set of diffractive features at least partially overlap within the out-coupling diffractive optic, wherein the first and second set of diffractive features introduce an optical power to change a focusing distance of the first wavelength range and the second wavelength range of image-bearing light beams.