LiDAR Mask Spatial Filtering for Ambient Light Rejection
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Solution Overview
Problem
Current LiDAR systems face challenges in detecting both bright objects at close range and low-reflectivity objects at long range with the same system configuration, and they struggle with ambient light interference, which affects their accuracy and efficiency, especially in automotive applications.
Innovation Solution
A LiDAR detection system employing synthetic Doppler processing and spatial filtering, using a scanning device with a mask and optical transmission elements to modulate and filter the optical signals, allowing for envelope-modulated output signals to be transmitted and received with a two-dimensional array of detectors, enabling effective detection of objects across varying ranges and reducing ambient light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional LiDAR systems use standard detection methods, then they can detect bright objects at close range, but they fail to detect low-reflectivity objects at long range simultaneously
Solution Approach 1:
The detection process is segmented into multiple stages: initial ambient light filtering using spatial masks, followed by staged integration where signals are processed through multiple accumulation stages. This segmentation allows the system to handle different object reflectivity levels separately, improving overall detection versatility while maintaining precision for challenging targets.
Solution Approach 2:
The system performs preliminary spatial filtering and ambient light rejection before main detection processing. By pre-processing the optical signals through masks and spatial filters that block scattered light paths, the system prepares cleaner signals for subsequent detection stages, enabling accurate detection of low-reflectivity objects at long range while maintaining capability for bright close-range objects.
2Measurement precision
If LiDAR systems increase signal integration time to improve detection of low-reflectivity objects, then detection sensitivity improves, but frame rate and real-time performance deteriorate
Solution Approach 1:
The integration process is divided into multiple parallel pathways with different integration depths. Some detector elements perform shallow integration for high-speed detection of bright objects, while others perform deeper integration for sensitive detection of low-reflectivity objects. This segmented approach allows simultaneous high frame rate operation and high sensitivity detection without requiring all pixels to undergo lengthy integration.
Solution Approach 2:
The system applies partial integration strategies where only necessary detector elements perform extended integration for low-reflectivity object detection, while other elements maintain shorter integration times for high frame rate operation. This selective partial action allows the system to achieve enhanced sensitivity for specific targets without sacrificing overall frame rate performance.
3Measurement precision
If LiDAR systems use coherent detection methods to improve sensitivity and accuracy, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The system extracts only the essential coherent detection functionality needed for phase-sensitive measurements while removing unnecessary complexity. By implementing a simplified coherent detection architecture that focuses on key phase measurement capabilities and integrates closely with the detector array, the system achieves high measurement precision without the full complexity and cost of traditional separate coherent transceiver systems.
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 enhances the detection of objects by improving signal-to-noise ratio, increasing the dynamic range, and allowing for the simultaneous detection of bright and low-reflectivity objects, while reducing ambient light interference, thereby improving the accuracy and effectiveness of LiDAR systems in automotive applications.
Implementation Method 1
A mask is disposed in proximity to the array between the region and the array, the return optical signals impinging on the mask, the mask comprising a plurality of apertures disposed along a direction aligned with a first dimension of the array
Implementation Method 2
A modulation circuit receives the output signal from the signal generator and applies the output signal from the signal generator to the plurality of optical sources to modulate the output optical signals such that the output optical signals are envelope-modulated output optical signals having frequency modulated modulation envelopes
Implementation Method 3
A scanning device scans the plurality of envelope-modulated output optical signals over a second direction different than the first direction
Implementation Method 4
A receiver receives return optical signals at least partially generated by reflection of the transmitted envelope-modulated output optical signals and generates receive signals indicative of the return optical signals, the receiver comprising a two-dimensional array of optical detectors
Implementation Method 5
A processor is coupled to the receiver for receiving the receive signals and processing the receive signals to generate detections of one or more objects in the region
Data Source
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AI summary
A LiDAR detection system includes optical sources generating a plurality of output optical signals disposed along a first direction. A modulation circuit applies an output signal from a signal generator to the optical sources to modulate the output optical signals such that the output optical signals are envelope-modulated output optical signals having frequency-modulated modulation envelopes. A scanning device scans the output optical signals into a region over a second direction. A receiver comprising a two-dimensional array of optical detectors receives return optical signals and generates receive signals indicative of the return optical signals. The return optical signals impinge on a mask between the region and the array, the mask comprising a plurality of apertures aligned with a first dimension of the array. The receive signals are generated for a set of detectors in the array disposed along the first dimension of the array and aligned with the mask apertures.