Optical Light Guide With Complementary Microstructures

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Solution Overview

Problem

Current optical guides suffer from interference and diffraction issues when trying to superimpose an image on a scene beyond the guide, leading to poor image quality and increased manufacturing complexity and cost.

Innovation Solution

An optical guidance device with a first part for propagating light beams through successive reflections and a second part with complementary microstructures separated by a transparent medium of constant thickness, minimizing diffraction and allowing for reliable, cost-effective manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If interstitial spaces are used between microstructures to enable see-through vision, then transparency is improved, but diffraction interference occurs degrading image quality

Engineering Contradiction:
ImprovetransparencyVSAvoidimage quality
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

A layer of transparent material with refractive index different from air is introduced as an intermediary substance in the interstitial spaces between microstructures. This mediator reduces the refractive index contrast at the interfaces, thereby minimizing diffraction interference while preserving the see-through transparency function.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The refractive index parameter of the medium in interstitial spaces is changed from air (n≈1.0) to a transparent material with higher refractive index (n>1.0). This parameter change reduces the optical contrast at microstructure interfaces, suppressing diffraction effects while maintaining transparency.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If microstructures with parallel faces are used for light extraction, then manufacturing is simplified, but diffraction artifacts and parasitic images are generated

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidimage quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The microstructures are designed with asymmetric geometry, specifically with at least one face having an angle different from 90 degrees relative to the base. This asymmetric design breaks the parallel face symmetry that causes diffraction artifacts, while still allowing effective light extraction and maintaining manufacturing feasibility.

Inventive Principle:
Principle #4Asymmetry

3Stability of the object's composition

If a single integrated optical guide is manufactured, then structural integrity is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvestructural integrityVSAvoidmanufacturing complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The optical guide is segmented into multiple separate components (first optical guide portion, second optical guide portion, and transparent material layer) that are manufactured independently and then assembled. This segmentation simplifies the manufacturing process for each component while maintaining the structural integrity of the complete assembly through precise interfacing.

Inventive Principle:
Principle #1Segmentation

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 solution enhances image quality by reducing interference and diffraction, ensuring clear vision of both the image and the external scene while simplifying and reducing the manufacturing costs of the optical guidance device.

Implementation Method 1

The first part, in a transparent material, adapted to propagate the light beam by successive reflections

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

comprising a flat surface adapted to allow the exit from the ray-guiding device of the light beam coming hit said flat surface

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP2695017B1Optical light guiding device and method of manufacturing the device
Publication Date: 2018.10.24 OPTINVENT
  • EP2695017B1 patent drawingFigure 1~2
  • EP2695017B1 patent drawingFigure 3~5
  • EP2695017B1 patent drawingFigure 6~7

AI summary

A device for optical guidance of a light beam comprises a first part (1.5), of a transparent material, adapted for propagating the light beam (1.6) by successive reflections. This first part comprises an extraction section comprising at least one microstructure comprising a plane surface adapted for allowing the exit from the guidance device of rays of the light beam striking said plane surface. The device also comprises a second part (1.10), of a material substantially identical to that of said first part, comprising a section comprising at least one microstructure of shape complementary to that (those) of the extraction section. The device also comprises a layer of adhesive gluing the first and second parts in such a way that any microstructure of the extraction section is separated from its complementary microstructure by a transparent medium of substantially constant thickness.