Multifocal XR Optical Assembly for Fixed-Structure Focus

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Solution Overview

Problem

Conventional XR devices suffer from vergence-accommodation conflict (VAC) due to a fixed focus distance, leading to user discomfort, visual strain, blurred perception, and cybersickness, and existing solutions like varifocal mechanisms and multilayer light field displays are complex, resource-intensive, and inefficient.

Innovation Solution

A multifocal optical assembly with fixed focusing lenses providing multiple focus distances is used to present virtual content at different depths, mimicking natural human focus, eliminating the need for real-time image plane adjustments and reducing complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a fixed focus distance is used in conventional XR devices, then the device structure is simple, but user comfort deteriorates due to vergence-accommodation conflict

Engineering Contradiction:

Improvedevice structureVSAvoiduser comfort

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The optical assembly is segmented into multiple lens portions, each with different focal lengths, allowing the system to provide multiple focus distances simultaneously while maintaining a fixed overall structure. This segmentation resolves the contradiction by enabling multifocality without requiring complex varifocal mechanisms.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the optical assembly have different optical properties (different focal lengths) to address different viewing zones. The first lens portion handles near-view content while the second lens portion handles far-view content, providing localized optical quality optimization without complex global adjustment mechanisms.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If varifocal mechanisms are used to adjust focus distance, then user comfort improves, but device complexity increases

Engineering Contradiction:

Improveuser comfortVSAvoiddevice structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Instead of using a single adjustable lens that changes focus dynamically, the patent inverts the approach by using multiple fixed lenses with different focal lengths. This eliminates the need for complex adjustment mechanisms while achieving the same functional goal of providing multiple focus distances.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent creates multiple optical paths with different focal lengths rather than adjusting a single optical path. This copying approach provides multiple focus options simultaneously without requiring the complexity of dynamic adjustment mechanisms.

Inventive Principle:

Principle #26Copying

3Adaptability or versatility

If multilayer light field displays are used, then multiple focus distances are achieved, but resource consumption increases

Engineering Contradiction:

Improvefocus distance rangeVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces complex multilayer light field display systems with a simpler optical assembly using multiple lens portions. This substitution achieves the same multifocal functionality with reduced computational and resource demands.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Manufacturing precision

If real-time image plane adjustments are made, then display quality improves, but computational demands increase

Engineering Contradiction:

Improvedisplay qualityVSAvoidcomputational demands

Core Design Contradiction:

Manufacturing precisionVSPower

Solution Approach 1:

The optical assembly is pre-configured with multiple lens portions designed for specific focus distances. This preliminary configuration eliminates the need for real-time computational adjustments, as the correct focal length is already determined by the optical path selected.

Inventive Principle:

Principle #10Preliminary action

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 multifocal assembly enhances user comfort by allowing clear focus across various depths without additional components, reducing power consumption and computational demands, and improving display quality.

Implementation Method 1

a first lens portion of a focusing lens of the optical assembly directs the first virtual content to be displayed at the first image plane

Methodology Applied

Scientific EffectLight refraction through lens: Lens

Implementation Method 2

a second lens portion of the focusing lens directs the second virtual content to be displayed at the second image plane

Methodology Applied

Scientific EffectLight refraction through lens: Lens

Data Source

PatentUS20250322597A1Multifocal assembly for extended reality devices

Publication Date: 2025.10.16 SNAP INC

AI summary

A head-wearable extended reality (XR) device includes an optical assembly. The optical assembly has a display and an optical element. The display is provided to display virtual content to a user of the XR device. The optical element is provided to direct the virtual content from the display along an optical path to an eye of the user. The optical element includes a first portion and a second portion. The first portion provides a first focus distance that corresponds to a first viewing zone of the display. The second portion provides a second focus distance that differs from the first focus distance and corresponds to a second viewing zone of the display.