Parallel FMCW LiDAR Processing Units for Real-Time 3D Scanning
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Solution Overview
Problem
Existing FMCW LiDAR scanners face challenges in collecting enough distance information in a short time to generate three-dimensional images of the environment in real time, particularly in autonomous vehicles, due to the need for robust and reliable systems without sensitive moving components.
Innovation Solution
The implementation of a device with several parallel and independent processing units connected to a common light source, utilizing a small distribution matrix and optical circulator to maintain a high signal-to-noise ratio, allowing for simultaneous distance measurements across multiple frequency bands, and employing a grating or dispersive optical element for scanning in all three spatial directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple distance measurements are performed simultaneously using parallel processing units, then the productivity of distance information collection is improved, but the device complexity increases due to multiple processing units and distribution matrices
Solution Approach 1:
The system divides the distance measurement function into multiple parallel processing units (first processing unit, second processing unit, etc.), each independently performing measurements. This segmentation enables simultaneous multi-directional scanning, improving productivity while keeping each individual processing unit relatively simple in structure
Solution Approach 2:
Multiple processing units share common components including the light source, optical circulator, and evaluation device. This multi-functionality approach allows each processing unit to perform distance measurements in different spatial directions while utilizing shared resources, improving productivity without proportionally increasing overall device complexity
2Area of stationary object
If a large distribution matrix is used to scan multiple directions, then the coverage area is improved, but the signal attenuation increases causing lower signal-to-noise ratio
Solution Approach 1:
The distribution matrix function is segmented across multiple processing units, each handling a specific spatial direction or sector. This segmentation reduces the size of individual distribution matrices compared to a single large matrix, thereby reducing signal attenuation and improving signal-to-noise ratio while maintaining comprehensive scanning coverage through parallel operation of multiple units
Solution Approach 2:
Optical circulators serve as intermediaries between the light source and distribution matrices, and between distribution matrices and detectors. These circulators enable bidirectional optical signal routing with minimal loss, allowing measurement signals to pass through fewer optical components and reducing overall signal attenuation in the system
3Power
If high optical intensities are used to ensure sufficient output signal intensity, then the signal strength is improved, but the reliability decreases due to potential damage to optical switches
Solution Approach 1:
The optical power distribution is segmented across multiple processing units, each with its own distribution matrix. This segmentation allows the total optical power to be divided into smaller portions for each processing unit, reducing the intensity requirements for individual distribution matrices and protecting optical switches from damage while maintaining sufficient output signal intensity through parallel processing
Solution Approach 2:
Optical circulators act as intermediaries that route optical signals efficiently, minimizing the number of optical switches each signal must pass through. This reduces cumulative insertion loss and allows lower input intensities to achieve sufficient output intensities, thereby protecting optical switches from damage while maintaining signal quality
4Adaptability or versatility
If the number of optical components in the signal path is increased to enable multi-directional scanning, then the scanning versatility is improved, but the signal attenuation increases reducing measurement precision
Solution Approach 1:
The optical signal path is segmented into multiple parallel processing units, each with its own compact distribution matrix and detector. This segmentation reduces the number of optical components in each individual signal path compared to a single large-scale scanning system, minimizing signal attenuation while maintaining multi-directional scanning versatility through parallel operation of multiple units
Solution Approach 2:
Optical circulators serve as intermediaries that enable efficient bidirectional signal routing with minimal insertion loss. By positioning circulators strategically in the optical path, the system reduces the number of optical switches and components that measurement signals must pass through, thereby reducing signal attenuation while maintaining versatile multi-directional scanning capability
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 enables reliable and efficient generation of three-dimensional images by reducing signal attenuation, avoiding high optical intensities that can damage components, and allowing for real-time scanning with a high pixel rate and sufficient signal-to-noise ratio, while minimizing the use of moving components.
Implementation Method 1
an optical signal with a time-varying frequency (FMCW stands for frequency modulated continuous wave) directed at the object to be measured
Implementation Method 2
If the Doppler shift is also taken into account, the relative velocity between the scanning device and the object can also be calculated
Implementation Method 3
recorded and evaluated after reflection from the object
Data Source
Figure 1~4
Figure 3
Figure 5a~5b
AI summary
A device (14) for scanning the distance to an object (12) has a light source (16) that generates an optical output signal with a time-varying frequency. The device comprises several optical processing units (PU1 to PU4) that are optically connected in parallel to the light source (16). Each processing unit (PU1 to PU4) has an optical distribution matrix (M1 to M4) with several optical switches (S11, S21, S22, S31 to S34) that allow optical output signals to be selectively distributed to different optical waveguides (W11 to W14). Optical output signals are coupled into free space via free-space couplers (FSC11 to FSC14), and optical output signals reflected from the object (12) are coupled into the waveguides as optical measurement signals. A detector (D1 to D4) detects a superposition of the optical measurement signal with the optical output signal generated by the light source (16).A circulator (C1 to C4) directs optical output signals supplied from the light source (16) to the distribution matrix (M1 to M4) and optical measurement signals coming from the distribution matrix (M1 to M4) to the detector (D1 to D4).