LIDAR Interference Rejection via Dual Photon Detector Segmentation
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Solution Overview
Problem
LIDAR systems face false positive object detection due to imperfect spatial light filtering by micromirror arrays, which allow non-IFOV light to be detected as if it were IFOV light, leading to interference with true return signals.
Innovation Solution
A LIDAR system employing two photon detectors, where one directs IFOV light to a first photon detector and non-IFOV light to a second photon detector, allowing for differential signal analysis to distinguish between true return signals and false positives by comparing their magnitudes and contrast ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single photon detector is used to receive light from the field of view, then the device complexity is reduced, but interfering signals from outside the instantaneous field of view cannot be effectively filtered, leading to false positive object detection
Solution Approach 1:
The patent divides the detection system into multiple photon detectors, where each detector is assigned to receive light from a specific region of the field of view. This segmentation allows the system to distinguish between light from the instantaneous field of view and light from outside the instantaneous field of view, thereby reducing false positive detections while maintaining manageable system complexity
Solution Approach 2:
The patent introduces multiple photon detectors as intermediary components that selectively receive and detect light from different regions of the field of view. These detectors act as mediators between the optical system and the signal processing system, enabling the differentiation and filtering of interfering signals before final object detection occurs
2Object-affected harmful factors
If micromirror arrays are used to filter non-IFOV light, then spatial light filtering is achieved, but imperfect filtering allows interfering signals to pass through and be detected as true return signals
Solution Approach 1:
The patent segments the detection function across multiple photon detectors, each responsible for a specific region. This segmentation creates multiple independent detection channels that can independently filter and identify interfering signals, improving overall signal filtering accuracy beyond what a single micromirror array can achieve alone
Solution Approach 2:
The patent complements the mechanical/optical filtering by micromirror arrays with an electronic/digital filtering approach using multiple photon detectors and signal processing. This substitution and combination of filtering methods allows for more precise rejection of interfering signals by analyzing the temporal and spatial characteristics of the detected signals
3Reliability
If multiple photon detectors are used to distinguish IFOV and non-IFOV light, then interfering signals can be filtered, but the device complexity increases
Solution Approach 1:
The patent designs the multiple photon detectors to serve multiple functions: they detect light from different regions of the field of view, provide temporal information about the laser pulse, and enable digital signal processing for interference rejection. This multi-functionality allows the system to achieve reliable false positive reduction without proportionally increasing complexity
4Area of stationary object
If the instantaneous field of view is expanded to capture more targets, then the coverage area increases, but more interfering signals from outside the original IFOV enter the detection region
Solution Approach 1:
The patent segments the expanded field of view into multiple regions, each monitored by a dedicated photon detector. This segmentation allows the system to maintain a large overall field of view coverage while simultaneously identifying and filtering interfering signals from outside the instantaneous field of view through the regional detection and processing capabilities
Solution Approach 2:
The patent implements feedback mechanisms where the detection signals from multiple photon detectors are processed to identify and reject interfering signals. The system continuously monitors the detection regions and uses the feedback information from signal analysis to dynamically filter out interfering signals, allowing expanded field of view coverage without proportionally increasing interfering signal impact
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 effectively filters out interfering signals, reducing false positive object detection by normalizing the output of the second photon detector to the contrast ratio of the first, thereby isolating and subtracting out false positives, leaving only true return signals.
Implementation Method 1
The receiver is configured to receive light from the field of view, and to focus a first portion of the received light, corresponding to a region of interest, on a first light directing element
Implementation Method 2
a first light directing element is configured to direct the first portion of the received light towards a first photon detector
Data Source
AI summary
In described examples, a LIDAR system includes a laser transmitter, a receiver, and first and second light directing elements. The laser transmitter is configured to scan a field of view with a laser beam. The receiver is configured to receive light from the field of view, and to focus a first portion of the received light, corresponding to a region of interest, on a first light directing element. The receiver is also configured to focus a second portion of the received light, corresponding to the field of view except for the region of interest, on multiple second light directing elements. The first light directing element is configured to direct the first portion of the received light towards a first photon detector, and the second light directing elements are configured to direct the second portion of the received light towards a second photon detector.