Optical Combiner Calibration Using Structured Light for Dynamic AR Accuracy

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Solution Overview

Problem

Existing augmented-reality systems with optical combiners face challenges in maintaining accuracy and reliability due to curvature changes caused by thermal expansion, mechanical stress, and wear and tear, especially in dynamic environments, leading to compromised spatial reconstruction and user experience.

Innovation Solution

A system and method using structured light to calibrate optical combiners by projecting light patterns, capturing reflections, and determining curvature based on shape distortions, enabling dynamic compensation of geometrical aberrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If static and pre-defined curvature compensation techniques are employed, then the system is simple to operate, but the accuracy of AR rendering deteriorates under dynamic conditions

Engineering Contradiction:

Improvesimplicity of calibrationVSAvoidaccuracy of AR rendering

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system transitions from static pre-defined curvature compensation to dynamic real-time curvature measurement and compensation. The optical combiner's curvature is continuously measured using structured light projection and camera capture, allowing the system to adapt to changing conditions while maintaining operational simplicity through automated calibration.

Inventive Principle:

Principle #15Dynamics

2Area of stationary object

If the field of view and viewing area are increased, then the user experience is improved, but the curvature of the optical combiner becomes highly significant and compromises spatial reconstruction

Engineering Contradiction:

Improvefield of viewVSAvoidspatial reconstruction accuracy

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

The system dynamically adjusts rendering parameters based on measured curvature values. By projecting structured light patterns and analyzing their reflections, the system determines the optical combiner's curvature and uses this information to compensate for geometric aberrations, maintaining spatial reconstruction accuracy across large fields of view.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If static curvature compensation is used, then the device complexity is low, but the reliability deteriorates due to thermal expansion and mechanical stress

Engineering Contradiction:

Improvecomplexity of curvature compensationVSAvoidreliability under thermal and mechanical stress

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system implements a feedback loop where the optical combiner's curvature is continuously measured using structured light projection and camera capture. The measured curvature values feed into the rendering pipeline, enabling real-time compensation for thermal expansion and mechanical stress effects, thereby maintaining reliability without excessive complexity.

Inventive Principle:

Principle #23Feedback

4Measurement precision

If real-time curvature measurement is implemented, then the accuracy and reliability are improved, but the computational complexity increases

Engineering Contradiction:

Improvecurvature measurement accuracyVSAvoidcomputational complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system replaces complex mechanical curvature sensing devices with an optical measurement approach using structured light projection and standard camera capture. This substitution achieves high measurement precision while keeping computational complexity manageable through efficient image processing algorithms and pattern recognition techniques.

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

Accurately and reliably determines curvature for enhanced realism and immersiveness in augmented-reality systems, supporting large fields of view and eye boxes with real-time, computationally-efficient calibration.

Implementation Method 1

project at least one light pattern onto a semi-reflective surface of the optical combiner; detect, in the at least one image, a reflection of at least a part of the at least one light pattern

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentEP4632464A1Calibrating optical combiner using structured light

Publication Date: 2025.10.15 DISTANCE TECHNOLOGIES OY

Figure 1~2
Figure 3A~3B
Figure 3C~3D

AI summary

Disclosed is a system (100) implemented in an enclosed space (302). The system comprises: light source(s) (102, 316); tracking camera(s) (104, 318, 412); an optical combiner (106, 320, 408) arranged on an optical path of a light field display unit (112, 326, 404) and on an optical path of a real-world light field (406) of a real-world environment (410); and processor(s) (108, 322, 414) configured to: control the tracking camera(s) to capture image(s) (350a-d) of the enclosed space, whilst controlling the light source(s) to project light pattern(s) (340a-b) onto a semi-reflective surface (334) of the optical combiner; detect, in the image(s), a reflection (352a-d) of at least a part of the light pattern(s) off surface(s) in the enclosed space, and determine a shape of said reflection; and determine a curvature of the optical combiner, based on shapes of at least said part of the light pattern(s) and the reflection.