3D Imaging System Phase Reference Averaging
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Solution Overview
Problem
Current 3-D imaging systems face challenges in achieving accurate depth measurement due to variations and drifts in electric propagation times and delays, which affect the synchronization of light signals, leading to reduced measurement accuracy.
Innovation Solution
A 3-D imaging method and system that uses a plurality of light emitting devices to emit modulated light, with a reference modulation phase calculated as an average of the modulation phases from these devices, providing a stable reference for depth calculation, and incorporates a reference light sensor to gather and average the modulation phases, reducing the impact of production tolerances and temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single light emitting device is used for phase reference, then device complexity is reduced, but measurement precision deteriorates due to variations and drifts in electric propagation times
Solution Approach 1:
The patent combines the light emitting function and light detecting function into a single imaging device. The imaging device includes both light emitting units that emit modulated light and lock-in pixel sensor cells that detect the reflected light, eliminating the need for separate reference light sources and sensors. This merging reduces device complexity while maintaining measurement precision through the integrated phase reference system.
Solution Approach 2:
The imaging device performs multiple functions: it emits modulated light for illumination, detects reflected light for depth measurement, and simultaneously provides phase reference for synchronization. The light emitting units and sensor cells work together to provide both the measurement signal and the reference signal, making the device universal and eliminating the need for separate dedicated reference components.
2Measurement precision
If electric propagation time measurement is used for synchronization, then device complexity is reduced, but measurement precision deteriorates due to unknown variations and drifts
Solution Approach 1:
The patent replaces electric signal-based synchronization with optical signal-based synchronization. Instead of using electric propagation time measurements that are subject to drift and variations, the system uses the optical carrier wave itself as the reference. The phase reference is derived from the actual emitted light through the lock-in detection mechanism, eliminating sensitivity to electric propagation time variations and improving reliability.
3Measurement precision
If high temporal resolution is required for spatial resolution in centimeters, then measurement precision is improved, but device complexity increases due to synchronization requirements
Solution Approach 1:
The patent implements a feedback mechanism where the detected light signal is used to generate the reference signal for phase comparison. The lock-in pixel sensor cells detect the reflected modulated light and use this signal to establish the phase reference, creating a closed-loop feedback system that automatically compensates for timing variations and simplifies synchronization while maintaining high temporal resolution.
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 the accuracy of depth measurement by averaging the modulation phases from multiple light emitting devices, improving the system's ability to maintain precision in distance calculations, particularly in applications requiring centimeter-level accuracy.
Implementation Method 1
an illumination unit for emitting light into a scene
Implementation Method 2
the modulated light being emitted by a plurality of individual light emitting devices... each of the light emitting devices emitting a part of the modulated light
Implementation Method 3
at least one reference light sensor for detecting a reference modulation phase of light emitted at the illumination unit
Implementation Method 4
an imaging sensor for imaging the scene by detecting scattered light
Implementation Method 5
determining the modulation phase of the light detected at the lock-in pixel sensor cells
Implementation Method 6
evaluation unit, for determining distance information related to the scene on the basis of light propagation time
Data Source
Figure 1~2
Figure 3
AI summary
For acquiring a 3-D image of a scene, the scene is illuminated with modulated light emitted by an illumination unit and imaged onto an array of lock-in pixel sensor cells, which detect the previously emitted light after it has been scattered or reflected by an object or a living being in the scene. One determines the modulation phase of the light detected at the lock-in pixel sensor cells and provides a reference modulation phase that stands in a known relationship with the modulation phase of the light at the time of the emission. Based upon the reference modulation phase and the modulation phase of the light detected at the lock-in pixel sensor cells one then calculates depth information on the scene. The modulated light is emitted by a plurality of individual light emitting devices of the illumination unit, each of the light emitting devices emitting a part of the modulated light, and the reference modulation phase is provided as an average of the modulation phases of the parts of modulated light emitted by the light emitting devices.