Switchable Diffuser ToF Depth Resolution
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Solution Overview
Problem
Conventional Time-of-Flight (ToF) technologies for depth determination using flood light illumination suffer from low accuracy and high cost, with a low signal-to-noise ratio due to interference from ambient light sources, and lack efficient utilization of available light sources, hindering advancements in device functionalities like facial recognition and 3D scene reconstruction.
Innovation Solution
A system that projects patterns of structured light, utilizing a ToF sensor to detect reflections and determine depth measures based on time-of-flight indications, with an optional switchable diffuser to oscillate between flood light and structured light projections, enhancing depth resolution and signal-to-noise ratio by selectively diffusing or transmitting light based on voltage control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flood light illumination is used for ToF depth determination, then the system is simple to implement, but the depth resolution and signal-to-noise ratio deteriorate due to ambient light interference
Solution Approach 1:
The illumination is segmented into multiple discrete light sources arranged in specific patterns (e.g., arrays of LEDs) rather than using uniform flood light. This segmentation allows the system to project structured light patterns that can be distinguished from ambient light, thereby improving depth resolution while maintaining implementation simplicity through patterned illumination.
Solution Approach 2:
Different regions of the illumination field are assigned different characteristics through structured light patterns. By varying the spatial distribution and intensity of light across different zones, the system enhances the ability to distinguish projected light from ambient light in specific areas, improving local depth measurement precision without requiring complete system redesign.
2Measurement precision
If multiple projection sources are used to achieve imaging objectives, then the imaging quality improves, but the device complexity and cost increase
Solution Approach 1:
A single light projecting subsystem is designed to perform multiple functions by projecting different structured light patterns sequentially or simultaneously. The same hardware infrastructure (light source, optical elements, controller) is used for various imaging objectives such as depth mapping, surface profiling, and 3D reconstruction, eliminating the need for multiple separate projection sources and reducing overall device complexity.
Solution Approach 2:
The system uses periodic modulation of light patterns from a single projection source to achieve multiple imaging objectives. By varying the temporal characteristics and spatial patterns of the projected light in a periodic manner, the system can extract different types of information from the reflected light, effectively replacing multiple static projection sources with one dynamically controllable source.
3Area of stationary object
If flood light sources are used for ToF measurements, then the system coverage is broad, but the signal-to-noise ratio deteriorates due to lack of differentiation from ambient light
Solution Approach 1:
The illumination system projects structured light patterns with distinct spatial characteristics across the broad coverage area. Each region receives a unique pattern or phase-modulated light that can be differentiated from ambient light through correlation analysis, maintaining wide area coverage while significantly improving the signal-to-noise ratio through pattern recognition.
Solution Approach 2:
The system pre-projects structured light patterns onto the target area before performing ToF measurements. By establishing known spatial patterns in advance, the system creates a reference framework that enables differentiation between projected light and ambient light during detection, improving signal-to-noise ratio across the entire illumination coverage area.
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 system achieves improved depth resolution and signal-to-noise ratio by using structured light projections, reducing noise and enhancing power density, while allowing for efficient use of light sources, thereby advancing device functionalities such as facial recognition and 3D scene reconstruction.
Implementation Method 1
with an optional switchable diffuser to oscillate between flood light and structured light projections, enhancing depth resolution and signal-to-noise ratio by selectively diffusing or transmitting light based on voltage control
Implementation Method 2
a ToF sensor configured to detect reflections of the projected pattern of structured light off of a surface, and provide one or more indications of a time-of-flight associated with one or more portions of the pattern of structured light
Data Source
AI summary
Systems and methods for projecting and detecting light are disclosed. Systems and methods for determining surface depth information using Time-of-Flight (“ToF”) detectors configured to measure time-of-flight in connection with flood light reflections, structured light reflections, and/or a fusion of both (e.g., in a selective, controlled, and/or patterned manner) are disclosed. Some portions of this disclosure also relate to embodiments of the technology configured for operation in connection with a switchable diffuser.