Optical See-Through HMD with Mutual Occlusion and Opaqueness Control

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Solution Overview

Problem

Existing optical see-through head-mounted displays (OST-HMDs) lack occlusion capability, causing virtual objects to appear 'ghost-like' and floating in the real world, which hinders the realistic merging of virtual objects into the real environment.

Innovation Solution

The development of an optical see-through head-mounted display (OST-HMD) with opaqueness control and mutual occlusion capability, utilizing a spatial light modulator (SLM) to modulate the see-through view and a beamsplitter to merge the virtual and see-through paths, while employing freeform optical technology to achieve a compact and lightweight design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a conventional optical see-through HMD is used, then the device structure is simple, but the virtual objects appear ghost-like and floating without occlusion capability

Engineering Contradiction:

Improvedevice structureVSAvoidocclusion capability

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The optical system is divided into separate functional modules: a first optical system for the virtual image path and a second optical system for the see-through path. This segmentation allows each subsystem to be optimized independently while maintaining overall system simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent embeds the spatial light modulator within the optical path at an intermediate image plane, nesting the occlusion control functionality within the existing optical structure. This allows occlusion capability to be added without significantly increasing external device complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Manufacturing precision

If occlusion capability is added to achieve realistic merging, then the immersion and depth perception are improved, but the device complexity increases

Engineering Contradiction:

Improveocclusion capabilityVSAvoiddevice structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The spatial light modulator serves multiple functions: it controls occlusion of virtual objects behind real objects, adjusts opaqueness of the see-through view, and enables mutual occlusion between virtual and real objects. This multi-functionality reduces the need for separate components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The spatial light modulator acts as an intermediary element placed at the intermediate image plane, mediating between the virtual image from the microdisplay and the real scene from the external environment. This single intermediary component handles all occlusion and opaqueness control requirements.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If traditional optical components are used, then the occlusion capability is achieved, but the device becomes bulky and heavy

Engineering Contradiction:

Improveocclusion capabilityVSAvoiddevice weight

Core Design Contradiction:

Manufacturing precisionVSWeight of moving object

Solution Approach 1:

The patent folds the optical paths into two layers using reflective surfaces, transitioning from a linear single-layer layout to a compact multi-layer configuration. This dimensional reorganization reduces the overall device volume and weight while maintaining optical functionality.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

4Volume of moving object

If the optical paths are folded into two layers, then the device form factor is compacted, but the alignment precision becomes more difficult

Engineering Contradiction:

Improvedevice form factorVSAvoidalignment precision

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent merges the virtual view path and see-through path at the intermediate image plane, where both optical paths converge. This merging point serves as a common reference for alignment, simplifying the precision requirements compared to maintaining separate parallel paths.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces complex mechanical alignment mechanisms with optical design solutions, using the intermediate image plane as a natural convergence point that inherently guides alignment. This substitution reduces mechanical complexity while maintaining precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enables realistic occlusion of virtual objects over real objects and vice versa, enhancing the depth perception and immersion in augmented reality applications, while achieving a compact and wearable form factor.

Implementation Method 1

The virtual view path is merged with the see-through path by a beamsplitter

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

a spatial light modulator (SLM) to modulate the see-through view

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentUS20250028166A1Apparatus for optical see-through head mounted display with mutual occlusion and opaqueness control

Publication Date: 2025.01.23 MAGIC LEAP INC

AI summary

The present invention comprises a compact optical see-through head-mounted display capable of combining, a see-through image path with a virtual image path such that the opaqueness of the see-through image path can be modulated and the virtual image occludes parts of the see-through image and vice versa.