Optical Guide Doubler Element for Homogeneous Pupillary Zone

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Solution Overview

Problem

Optical guides used for transporting collimated images face challenges in providing a homogeneous pupillary zone without 'holes' due to the complexity and cost of manufacturing, as well as the difficulty in enlarging the field of vision in two dimensions, with existing solutions either being difficult to implement or introducing parasitic images.

Innovation Solution

The optical guide incorporates a doubler element with semi-reflective mirrors arranged at specific distances and angles to ensure complete coverage of the pupillary zone by doubling the cross-section of light beams in both dimensions, using a combination of rectangular parallelepipeds with planar and parallel faces and semi-reflective mirrors, optimizing the length and arrangement of mirrors to prevent symmetrical beam incidence and minimize the component's length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If multiple semi-reflective plates are used to enlarge the pupillary zone in two dimensions, then the field of vision is widened, but the manufacturing complexity and cost increase significantly

Engineering Contradiction:

Improvepupillary zone areaVSAvoidmanufacturing complexity

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

The optical guide is divided into two perpendicular elements, each containing semi-reflective plates oriented in different directions. This segmentation allows each element to independently enlarge the pupil in one dimension, achieving two-dimensional coverage without requiring a complex single-element solution with numerous plates

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention introduces a doubler element that contains mirrors nested within the optical guide structure. These mirrors are positioned to reflect light beams back through the semi-reflective plates, effectively doubling the beam cross-section and filling pupillary holes without adding external complexity to the overall device

Inventive Principle:

Principle #7Nested doll (Nesting)

2Manufacturing precision

If the injection section is enlarged to cover the entire guide face, then beam coverage is improved, but the device becomes more difficult to manufacture in two dimensions

Engineering Contradiction:

Improvebeam coverage uniformityVSAvoidinjection section enlargement

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Instead of enlarging the injection section in two dimensions simultaneously (which is difficult), the invention uses the third dimension (depth within the guide) by introducing a doubler element. This element uses mirrors positioned at specific depths to reflect and double the beams, achieving uniform coverage without requiring a large two-dimensional injection section

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Illumination intensity

If semi-reflective plates are used to double light beams in one direction, then beam coverage is improved, but parasitic images are introduced

Engineering Contradiction:

Improvebeam coverageVSAvoidparasitic images

Core Design Contradiction:

Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The doubler element uses mirrors with specific local properties (high reflectivity, precise positioning) only where needed to double the beams. The mirrors are positioned and oriented to reflect light along the intended optical path while avoiding configurations that would create parasitic images, providing localized beam enhancement without the harmful side effects of less precise semi-reflective plate arrangements

Inventive Principle:

Principle #3Local quality

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 effectively fills pupillary 'holes' and achieves a homogeneous exit pupil, simplifying the manufacturing process and reducing the complexity and cost of the optical guide while maintaining high luminance levels and minimizing parasitic images.

Implementation Method 1

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

The light beams output by the displayer propagate by total reflection inside the optical guide, are reflected by the semi-reflective plate 12 and exit the optical guide towards the eye of the user O

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS9182597B2Optical guide for collimated images with optical beam doubler, and associated optical device

Publication Date: 2015.11.10 THALES SA

AI summary

The general field of the invention is that of optical guides for collimated images comprising a first and a second image conductor functioning by total reflection, each conductor comprising a plurality of plates that are planar, semi-reflective, mutually parallel and inclined with respect to the plane of the external faces of the image conductors. The two conductors are arranged so as to deliver a collimated image to a large pupil. The optical guide according to the invention comprises an optical beam doubler element having substantially the shape of a rectangular parallelepiped. In its basic version, it comprises four external planar facets, two internal semi-reflective planar mirrors, said mirrors being mutually perpendicular, a planar entrance face intended to receive a collimated image, and an exit face adhesively bonded to the injection section of one of the image conductors. The invention also relates to the whole of the display device associated with this optical guide.