Hybrid Diffractive Reflective Optical Assembly for Near-Eye Displays

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Solution Overview

Problem

Conventional optical aperture expansion using diffractive components suffers from chromatic dispersion, limiting the achievable field of view and requiring narrowband light sources or complex design to cancel dispersion.

Innovation Solution

The use of a combination of diffractive and reflective optical components, including a pair of matching diffractive optical components and a reflective optical component with partially reflective surfaces, to achieve two-dimensional expansion of coupled-in light, thereby reducing chromatic dispersion and expanding the field of view.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If diffractive optical components are used for aperture expansion, then the field of view can be expanded, but chromatic dispersion occurs causing distortions and noise

Engineering Contradiction:

Improvefield of viewVSAvoidchromatic dispersion

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent combines diffractive optical components with reflective optical components in a hybrid optical assembly. The diffractive elements (gratings) provide aperture expansion while the reflective elements (mirrors) cancel chromatic dispersion by reflecting different wavelengths at angles that compensate for diffractive dispersion, thereby resolving the contradiction between expanding field of view and eliminating chromatic dispersion

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The optical assembly uses a composite structure combining different optical mechanisms - diffractive elements (transmissive or reflective gratings) and reflective elements (mirrors with specific orientations). This composite approach allows the system to simultaneously achieve aperture expansion through diffraction while canceling chromatic dispersion through reflection, resolving the technical contradiction

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If narrowband light sources are used to reduce chromatic dispersion, then chromatic dispersion is reduced, but the light source requirements become more restrictive and complex

Engineering Contradiction:

Improvechromatic dispersionVSAvoidlight source requirements

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

Instead of trying to eliminate chromatic dispersion through narrowband sources, the patent converts the harmful effect of chromatic dispersion into a beneficial cancellation mechanism. The reflective optical components are designed to introduce opposite chromatic dispersion that cancels the diffractive dispersion, allowing the use of broadband light sources while eliminating the harmful effects of chromatic dispersion

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Object-affected harmful factors

If diffractive components are designed to cancel dispersion of each other, then chromatic dispersion is reduced, but the design complexity increases

Engineering Contradiction:

Improvechromatic dispersionVSAvoiddesign complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges diffractive and reflective optical components in a hybrid assembly, where the reflective components handle chromatic dispersion cancellation while the diffractive components focus on aperture expansion. This division of functional responsibilities simplifies the overall design compared to using only diffractive components for both purposes

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

This approach effectively reduces distortions and noise, enhances the field of view, and simplifies the design by eliminating the need for polarization management and reducing design constraints on individual components.

Implementation Method 1

Conventional diffractive elements introduce chromatic dispersion where light-rays with different wavelengths diffract at different angles

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

a reflective optical component including a sequence of a plurality of partially reflective, mutually parallel surfaces

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS20250155627A1Light guide optical assembly

Publication Date: 2025.05.15 LUMUS LTD

AI summary

An optical assembly for optical aperture expansion combines facet reflective technology with diffractive technology. At least two diffractive components having opposite optical power (matching) are used, so that chromatic dispersion introduced by the first diffractive component will then be cancelled by the second diffractive component. The two diffractive components are used in combination with a reflective optical component to achieve more efficient aperture expansion (for near eye display), reducing distortions and noise, while also reducing design constraints on the system and individual components, as compared to conventional techniques. The assembly eliminates and/or reduces the need for polarization management, while enabling wider field of view. In addition, embodiments can have reduced nonuniformity, as compared to conventional single technology implementations, since the distortion patterns of the two technologies do not correlate.