Hybrid TOF Triangulation Optoelectronic Module
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Solution Overview
Problem
Time-of-flight (TOF) and triangulation-based optoelectronic modules face limitations in distance resolution and suffer from multi-path measurement inaccuracies, particularly when dealing with objects at close distances or in environments with multiple reflective surfaces.
Innovation Solution
The implementation of a hybrid TOF-triangulation mode in optoelectronic modules, which combines time-of-flight and triangulation techniques using a demodulation pixel and processor to correlate phase shifts with intra-pixel distances, allowing for improved distance data resolution and mitigation of multi-path inaccuracies by optimizing parameters for optimal phase-shift data collection in both modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If triangulation approach is used for distance measurement, then measurement precision is improved for close distances (about 1 cm or less), but device complexity increases due to additional optical elements and baseline requirements
Solution Approach 1:
The patent merges TOF and triangulation approaches into a hybrid system that can operate in both modes. The same optoelectronic module with demodulation pixels can perform TOF measurements using phase shift detection or triangulation measurements using focal plane position, eliminating the need for separate optical systems for each method.
Solution Approach 2:
The optoelectronic module is designed to perform multiple functions: it can operate in TOF mode for longer distances and triangulation mode for close distances. The demodulation pixels serve dual purposes by detecting both phase shift information and focal plane position information from the same optical path.
2Measurement precision
If pixel array resolution is increased to improve distance resolution, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent introduces a new dimension for measurement by utilizing the focal plane position of light spots across different pixels in addition to phase shift detection. This spatial dimension provides triangulation capability without requiring higher pixel density, as the baseline distance between optical axis and illumination source creates angular separation that maps to pixel position.
3Measurement precision
If TOF approach is used for distance measurement, then measurement precision is improved for long distances (greater than about 1 cm), but multi-path measurement inaccuracies occur in environments with multiple reflective surfaces
Solution Approach 1:
The patent uses the optical system's focal plane as an intermediary to distinguish direct path light from multi-path light. Direct path light focuses at a specific position on the demodulation pixel, while multi-path light from different angles focuses at different positions, allowing the system to identify and filter out multi-path interference through spatial analysis.
4Device complexity
If a single optical system is used for both TOF and triangulation modes, then device complexity is reduced, but adaptability to different distance ranges is limited
Solution Approach 1:
The patent implements dynamic mode switching capability where the system can adaptively choose between TOF mode and triangulation mode based on the measured distance range. The control system adjusts operational parameters such as modulation frequency and signal processing algorithms to optimize performance for the current operating conditions.
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 enhances distance measurement accuracy by minimizing noise and resolving multi-path issues, enabling precise distance determination across various object distance ranges and environments, potentially obviating the need for high pixel array resolution.
Implementation Method 1
The demodulation pixel and supporting circuitry, may detect a phase shift in the reflected light, wherein the phase shift may be further correlated to the distance the light traveled
Implementation Method 2
light projected from the light source and reflected by an object in a scene may be focused onto the pixel array via the optical elements
Data Source
AI summary
An optoelectronic module operable to collect distance data via a time-of-flight mode and a time-of-flight-triangulation mode includes an illumination assembly and an imaging assembly. The imaging assembly includes at least one demodulation pixel operable to determine distance to an object via a time-of-flight mode and a time-of-flight-triangulation mode. Multi-path distance inaccuracies can be mitigated in some implementations.