Waveguide Defect Control via Residual Wavefront Intensity
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Solution Overview
Problem
Existing light engines, particularly in holographic projectors and head-up displays, face challenges in detecting defects downstream of the holographic reconstruction, such as in waveguides, which can cause intensity variations and are not detectable by measuring the intensity of the holographic reconstruction alone, as these defects scatter light and change the proportion of reflected and transmitted light, leading to inconsistent image quality.
Innovation Solution
A light engine with a light sensor positioned to measure the intensity of residual holographic wavefronts after waveguiding by a waveguide with partially transmissive-reflective surfaces, allowing for the detection of defects and their location within the waveguide, as the residual portion of the wavefront contains useful intensity information that deviates from expected levels when a defect is present.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light sensor measures the intensity of the holographic reconstruction to monitor light output, then faults upstream of the holographic reconstruction (such as laser or display device faults) can be detected, but faults downstream of the holographic reconstruction (such as waveguide defects) cannot be detected
Solution Approach 1:
The patent introduces a new measurement dimension by placing the light sensor at the edge of the waveguide to detect residual wavefront intensity, rather than measuring at the holographic reconstruction plane. This spatial dimension change enables detection of waveguide defects that were previously invisible to upstream measurement methods.
Solution Approach 2:
The patent uses the residual wavefront intensity as an intermediary indicator to indirectly detect waveguide defects. The residual wavefront acts as a mediator that carries information about waveguide health from the waveguide interior to the external sensor, enabling defect detection without direct waveguide inspection.
2Adaptability or versatility
If the waveguide is designed with partially transmissive-reflective surfaces to generate replicas of the input wavefront, then the desired waveguiding and image replication function is achieved, but defects in the waveguide cause scattering and intensity variations that degrade image quality
Solution Approach 1:
The patent implements a feedback mechanism where the light sensor continuously monitors residual wavefront intensity and provides information about waveguide health. This feedback enables real-time detection of defects that cause scattering and intensity variations, allowing for timely intervention to maintain image quality consistency.
Solution Approach 2:
The patent performs preliminary detection of waveguide defects before they significantly degrade image quality. By monitoring residual wavefront intensity, the system can identify defects early in their development, enabling preventive maintenance before image quality is adversely affected.
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
Enables the detection and localization of defects in waveguides, facilitating timely and targeted repairs, ensuring consistent light output and improved image quality by identifying changes in intensity that indicate damage or degradation within the waveguide.
Implementation Method 1
provide waveguiding of an input wavefront by internal reflection between the first and second surfaces
Implementation Method 2
measure an intensity of the residual portion of the wavefront
Data Source
AI summary
A light engine for detecting a defect is provided. The light engine comprises a waveguide. The waveguide comprises a first surface that is partially transmissive-reflective, and a second surface opposite to the first surface. The waveguide is configured to receive, on an input port, an input wavefront and provide waveguiding of the input wavefront by internal reflection between the first and second surfaces thereby replicating the input wavefront along a replication direction. The light engine further comprises a light detector positioned to measure an intensity of a residual portion of the holographic wavefront after waveguiding is provided by the waveguide.