Switchable Diffractive Optical Element for AR Depth Sensing
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Solution Overview
Problem
Augmented reality (AR) systems employing multiple optical sensors face challenges due to high costs, complexity, mass, volume, and power consumption, particularly in integrating infrared (IR) depth sensing with visible light imaging, which limits their use in spectacle form factors.
Innovation Solution
An imaging system incorporating a switchable element and a diffractive element that selectively alters the direction of IR light without affecting visible light, allowing for simultaneous IR and visible light imaging using a single sensor, reducing the need for multiple sensors and enhancing field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple optical sensors are employed for AR systems, then depth sensing and visible light imaging capabilities are improved, but system complexity, mass, volume, and power consumption increase
Solution Approach 1:
The patent combines multiple optical sensing functions (visible light imaging and IR depth sensing) into a single integrated sensor system. The optical element includes a visible light sensor and an IR sensor that share common optical paths and processing circuitry, eliminating the need for separate sensors and reducing system complexity while maintaining both imaging capabilities.
Solution Approach 2:
The optical element is designed to perform multiple functions simultaneously - it can capture visible light for standard imaging, detect IR light for depth sensing, and operate in various modes (e.g., passive IR, active IR with illumination) depending on the application requirements, making it a universal sensor suitable for diverse AR applications.
2Adaptability or versatility
If multiple optical sensors with respective lenses and mechanical interfaces are used, then sensing capabilities are improved, but mass and volume increase significantly
Solution Approach 1:
The patent integrates multiple sensing functions into a single compact sensor module that shares common components including the optical element, lens, and processing circuitry. This merging approach dramatically reduces the volume compared to using separate sensors with individual lenses and mechanical interfaces.
Solution Approach 2:
The optical element is designed with nested functional layers where the IR sensing capability is integrated within the same physical structure as the visible light sensing capability. The sensors are arranged in a nested or overlapping configuration that maximizes space utilization and minimizes overall volume.
3Adaptability or versatility
If multiple optical sensors are integrated, then imaging functionality is improved, but power consumption increases
Solution Approach 1:
The patent combines multiple sensing functions into a single integrated sensor that shares power management resources, signal processing circuitry, and data processing pathways. This integration reduces redundant power consumption that would occur with separate sensors performing similar processing functions independently.
4Productivity
If a switchable element is used to direct IR light, then IR imaging efficiency is improved, but device complexity increases
Solution Approach 1:
The patent replaces mechanical switching mechanisms with an electronically controllable element (such as a liquid crystal shutter or electrochromic layer) that can be switched between transparent and opaque states using electrical signals. This substitution eliminates complex mechanical moving parts while maintaining the ability to control IR light transmission for depth sensing operations.
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 system complexity and power consumption while enabling efficient IR and visible light imaging, making it suitable for AR glasses by directing IR light away from the image sensor as needed, thus improving the form factor and functionality.
Implementation Method 1
one or more diffractive elements or layers, which are configured to selectively alter a direction of propagation of light within specified wavelengths of operation
Implementation Method 2
The switchable layer(s) may be independently switched (responsive to an applied electrical signal) between states that differently affect the polarization of light incident thereon
Data Source
AI summary
A multi-spectral optical imaging device includes a switchable element configured to be switched between first and second states, one of which alters a polarization of light, and a geometric phase element arranged to receive the light from the switchable element. The geometric phase element is configured to diffract a first wavelength band of the light to alter a direction of propagation thereof based on the polarization and without substantially altering a direction of propagation of a second wavelength band of the light, responsive to the first state of the switchable element. Related optical shutters and multi-spectral optical detectors are also discussed.