In-field Illuminator for Near-eye Depth Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Time of Flight (ToF) techniques struggle in very near-range contexts due to the difficulty in resolving the short time of flight of laser pulses, limiting their accuracy in depth sensing applications.
Innovation Solution
The use of near-infrared vertical-cavity surface-emitting lasers (VCSEL) to illuminate a diffractive optical element, generating a structured light projection or fringe interference pattern that is projected onto an eye, allowing for high-resolution near-range depth sensing by capturing images with a camera positioned to receive the reflection, enabling accurate three-dimensional depth mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Time of Flight (ToF) techniques are used for depth sensing, then depth measurement capability is provided, but measurement precision deteriorates in very near-range contexts due to difficulty in resolving short time of flight
Solution Approach 1:
The patent replaces the temporal measurement approach of ToF with a spatial measurement approach using structured light projection. Instead of measuring time of flight, the system projects known light patterns and analyzes their reflection geometry to calculate depth, substituting temporal resolution with spatial pattern recognition.
Solution Approach 2:
The patent changes the measurement parameter from time domain (time of flight) to spatial domain (light pattern geometry). By projecting structured light patterns and analyzing their reflection, the system transforms the depth measurement problem from resolving short time intervals to analyzing spatial light distribution, which is more suitable for near-range sensing.
2Measurement precision
If in-field illuminator is positioned close to the eye for near-range depth sensing, then depth sensing capability is improved, but visibility of the scene may be obstructed
Solution Approach 1:
The patent applies local quality by making the illuminator transparent or translucent only in the specific region where it is positioned near the eye, while maintaining opacity or different optical properties in other regions. This allows the illuminator to function optically for depth sensing while minimizing obstruction of the user's view of the scene.
Solution Approach 2:
The patent utilizes different wavelengths or optical properties for the illuminator compared to the visible scene. By using infrared or other non-visible wavelengths for illumination, the system enables depth sensing without obstructing the user's visible light view of the scene, effectively separating the sensing and viewing functions spectrally.
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 approach facilitates accurate near-range depth sensing within the field of view of a user, overcoming the limitations of ToF systems by providing clear visibility of the scene while enabling precise eye-tracking and three-dimensional mapping.
Implementation Method 1
near-infrared vertical-cavity surface-emitting lasers (VCSEL) to illuminate a diffractive optical element
Implementation Method 2
illuminate a diffractive optical element, generating a structured light projection or fringe interference pattern
Implementation Method 3
generating a structured light projection or fringe interference pattern
Implementation Method 4
capturing images with a camera positioned to receive the reflection
Data Source
AI summary
A near-eye optical device includes a transparent layer, an in-field illuminator, and a diffractive optical element (DOE). The in-field illuminator is configured to emit near-infrared light centered around a first wavelength. The diffractive optical element is configured to be illuminated by the near-infrared light emitted by the in-field illuminator. The DOE generates a structured light projection that includes dots that expand as the structured light projection propagates farther from the DOE. The structured light projection is directed to illuminate an eyebox.