3D Imaging With Dual CMOS Shutters for Precise Time-of-Flight
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Solution Overview
Problem
Existing 3D imaging systems, such as LIDAR, face challenges in achieving high performance and low cost due to the need for specialized timing devices or fast frame cameras, and conventional cameras have low time resolution, limiting their distance measurement accuracy.
Innovation Solution
A 3D imaging system using two CMOS cameras with different shutter delays and a delay generator to capture reflected photons, employing brightness-time and jitter calibration to determine time-of-flight with sub-nanosecond resolution, generating 3D coordinates and point clouds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional cameras are used for 3D imaging, then device cost is reduced and ease of manufacture is improved, but time resolution deteriorates (low time resolution limits distance measurement accuracy)
Solution Approach 1:
The patent changes the shutter timing parameters of conventional cameras to achieve sub-nanosecond effective time resolution. By controlling the shutter opening and closing times relative to laser pulse emission, the system extracts precise arrival time information from photons detected during specific exposure intervals, transforming the camera's temporal response characteristics to achieve high measurement precision without specialized detectors.
Solution Approach 2:
The system employs periodic shuttering of the cameras synchronized with periodic laser pulse emission. By alternating between exposure and non-exposure states in a controlled periodic manner, the cameras capture photon arrival times with sub-nanosecond precision. This periodic action allows conventional cameras to function as timing devices, resolving the contradiction between ease of manufacture and measurement precision.
2Measurement precision
If specialized timing devices or fast frame cameras are used to achieve high time resolution, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses conventional cameras as copies or substitutes for specialized timing devices. Instead of employing expensive fast frame cameras or dedicated timing electronics, the system leverages the shutter control mechanisms of standard cameras, which are much simpler and cheaper, to achieve the same sub-nanosecond time resolution. This copying approach reduces device complexity while maintaining measurement precision.
Solution Approach 2:
The patent makes conventional cameras multi-functional by enabling them to perform both imaging and precise timing functions. The same camera hardware that captures spatial information also provides temporal resolution through controlled shuttering, eliminating the need for separate specialized timing devices and reducing overall system complexity.
3Ease of manufacture
If conventional cameras with low time resolution are used, then device cost is reduced, but distance measurement accuracy deteriorates
Solution Approach 1:
The patent changes the operational parameters of conventional cameras, specifically the shutter timing and exposure duration, to extract precise arrival time information. By adjusting these parameters, the system achieves sub-nanosecond time resolution and corresponding high distance measurement accuracy (on the order of tens of centimeters) while using inexpensive conventional camera hardware.
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 high spatial resolution and sub-nanosecond time resolution for 3D imaging without specialized devices, enabling accurate distance measurement and cost-effective 3D reconstruction.
Implementation Method 1
a laser source configured to emit a laser pulse
Implementation Method 2
detect reflected photons of the laser pulse emitted by the laser source
Implementation Method 3
a first camera, a second camera... arranged and oriented to detect reflected photons
Data Source
AI summary
A 3D imaging system may include a laser source, a first camera, a second camera, a delay generator, and a computer. The first camera and the second camera may each be arranged and oriented to detect reflected photons of a laser pulse emitted by the laser source. The delay generator may be configured to provide a plurality of signals that active at least one of the laser source, the first camera, and the second camera. The computer may be configured to receive a first output signal from the first camera, receive a second output signal from the second camera, determine a time-of-flight based at least partially on the first and second output signals and a brightness-time calibration curve, convert the time-of-flight to a distance, determine a 3D coordinate based at least partially on the distance, and/or generate a 3D point cloud utilizing the 3D coordinate.