Holographic Waveguide Switchable Grating Rapid Illumination Mode

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Solution Overview

Problem

Current structured illumination devices for augmented reality applications are costly and bulky, and they struggle to rapidly switch between structured and uniform illumination patterns, which is essential for efficient data processing and wearable technology requirements.

Innovation Solution

A holographic waveguide device using switchable gratings and passive gratings to project structured and uniform illumination, where the gratings can switch between diffracting and non-diffracting states to provide efficient and rapid switching between the two illumination modes, utilizing a waveguide architecture for thin, lightweight, and versatile optical solutions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional projection devices are used for structured lighting, then structured illumination can be achieved, but the devices are costly and bulky

Engineering Contradiction:

Improvestructured illumination capabilityVSAvoiddevice size and cost

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent replaces conventional mechanical projection systems with a waveguide-based optical system using switchable gratings. The waveguide integrates multiple optical functions (light guidance, diffraction, modulation) into a thin substrate, eliminating bulky mechanical components while maintaining structured illumination capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The waveguide device performs multiple functions simultaneously: it guides light, creates structured patterns, and enables rapid switching between different illumination modes. The switchable grating structure allows the same device to function as both a structured light projector and a uniform illumination source, reducing overall system complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Illumination intensity

If conventional projectors are used for structured lighting, then illumination patterns can be projected, but switching between structured and uniform illumination is slow

Engineering Contradiction:

Improveillumination pattern switching capabilityVSAvoidswitching speed between illumination modes

Core Design Contradiction:

Illumination intensityVSSpeed

Solution Approach 1:

The patent employs switchable gratings that can dynamically change their diffraction properties in response to electrical signals. This allows rapid switching between structured and uniform illumination modes by electrically controlling the grating state, achieving microsecond-scale switching speeds compared to mechanical systems

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The switchable grating changes its physical state (refractive index modulation) in response to applied voltage, transitioning between diffracting and non-diffracting states. This parameter change enables rapid mode switching without mechanical movement, directly addressing the speed requirement

Inventive Principle:

Principle #35Parameter changes

3Speed

If switchable gratings are used in waveguide, then rapid switching between diffracting and non-diffracting states is achieved, but the device requires precise control of refractive index modulation

Engineering Contradiction:

Improveswitching speedVSAvoidrefractive index modulation control

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The patent uses HPDLC composite material combining liquid crystal droplets and polymer matrix. This composite structure provides high refractive index modulation capability while being controllable through electrical fields. The phase separation between liquid crystal-rich and polymer-rich regions creates the necessary optical properties with manageable manufacturing tolerances

Inventive Principle:

Principle #40Composite materials

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

The solution enables a low-cost, efficient structured light generator that can rapidly switch between structured and uniform illumination, meeting the requirements for augmented reality applications by providing a compact and versatile optical system suitable for wearable technology.

Implementation Method 1

at least one switchable grating switchable between a non-diffracting and a diffracting state

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

The parallel glass plates used to form the HPDLC cell provide a total internal reflection (TIR) light guiding structure

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP3433658B1Holographic waveguide apparatus for structured light projection

Publication Date: 2023.08.09 DIGILENS INC

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Figure 6A~7B

AI summary

A structured light projector comprising: a light source emitting light of a first wavelength; at least one switchable grating switchable between a non-diffracting and a diffracting state; and at least one passive grating. At least one of the switchable and passive gratings provides a first grating configuration for projecting uniform illumination in a first interval of time. At least one of the switchable and passive gratings provides a second grating configuration for projecting structured illumination in a second interval of time.