Bragg Grating Shear Steering for Compact Wearable Displays

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Solution Overview

Problem

Existing wearable electronic devices face challenges in providing a compact design for virtual image displays and camera systems due to limitations in pupil steering and field of view, leading to increased power consumption and bulkiness.

Innovation Solution

The use of Bragg gratings with applied shear forces to redirect light and re-position the pupil, allowing for variable orientation and focal length adjustments, enabling compact designs for both display and camera systems by steering light to match the viewer's eye movement and providing a suitable field of view without increasing device size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional pupil steering methods are used in wearable electronic devices, then the field of view can be adjusted, but the device becomes bulky and power consumption increases

Engineering Contradiction:

Improvefield of view adjustmentVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces conventional mechanical pupil steering mechanisms with a photonic crystal-based optical system. The photonic crystal structure manipulates light propagation through optical interference effects rather than mechanical movement, eliminating the need for bulky mechanical components and reducing power consumption while maintaining field of view adjustability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the optical parameters of the photonic crystal structure (such as lattice constant, material composition, or layer thickness) to dynamically adjust the field of view. This parameter-based control allows for compact design since it avoids mechanical actuation and enables precise control with minimal energy input

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If conventional optical systems are used for virtual image display, then the display function is achieved, but the device size increases

Engineering Contradiction:

Improvevirtual image display capabilityVSAvoiddevice size

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent replaces conventional optical components (lenses, mirrors, beam splitters) with a photonic crystal-based planar optical system. This substitution integrates multiple optical functions into a thin, flat structure that can be easily integrated into wearable devices without increasing size, while maintaining virtual image display capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent integrates multiple optical functions (light guidance, pupil steering, field of view control) within the nested hierarchical structure of the photonic crystal layers. The periodic lattice structure contains multiple functional layers that work together, allowing compact integration of complex optical functions in a minimal volume

Inventive Principle:

Principle #7Nested doll (Nesting)

3Productivity

If light is redirected without precise pupil steering, then the optical system is simpler, but light is wasted and efficiency decreases

Engineering Contradiction:

Improveoptical efficiencyVSAvoidoptical system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent uses photonic crystal-based optical interference to achieve precise light redirection and pupil steering without mechanical complexity. The periodic structure naturally guides light along specific paths through bandgap engineering, achieving high optical efficiency with a simple planar structure that requires no complex mechanical steering mechanisms

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The photonic crystal structure performs pupil steering and light guidance functions passively through its inherent optical properties. The periodic lattice structure automatically redirects light according to the Bragg condition without requiring external control mechanisms, achieving high efficiency with minimal system complexity

Inventive Principle:

Principle #25Self-service

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 reduces power consumption by minimizing wasted light and allows for compact, efficient designs in wearable devices, enabling holographic and three-dimensional displays with a suitable field of view while maintaining a compact form factor.

Implementation Method 1

a plurality of Bragg gratings configured to redirect the light

Methodology Applied

Scientific EffectBragg diffraction: Bragg Diffraction

Implementation Method 2

an actuator configured to apply a shearing force to the film. The shearing force manipulates an orientation of the plurality of Bragg gratings

Methodology Applied

Scientific EffectShear stress: Shear Stress

Data Source

PatentUS10582172B2Optical system steering via Bragg grating shear

Publication Date: 2020.03.03 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

An optical system includes a light source, a film positioned to be illuminated by light from the light source, the film including a plurality of Bragg gratings configured to redirect the light, and an actuator configured to apply a shearing force to the film. The shearing force manipulates an orientation of the plurality of Bragg gratings to change an extent to which the plurality of Bragg gratings redirects the light and to thereby re-position a pupil at which the light converges after redirection by the plurality of Bragg gratings.