Geiger-mode APD Pixel Asynchronous Reset for Multi-Return LiDAR
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Solution Overview
Problem
Prior Time-of-Flight (TOF) LiDAR systems using Geiger-mode avalanche photodiodes are limited as each pixel can only detect one reflection per detection frame, rendering it unusable for the remainder of the frame, leading to incomplete data collection and potential obscuration of objects.
Innovation Solution
Incorporating circuitry within each pixel for asynchronous automatic resetting and rearming of Geiger-mode avalanche photodiodes, allowing multiple reflections to be detected during a single detection frame, along with a TOF register module for timestamping each reflection, enabling multiple-return capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Geiger-mode avalanche photodiode detects a reflection during a detection frame, then the reflection is successfully detected and timestamped, but the pixel becomes blinded and unusable for the remainder of the detection frame
Solution Approach 1:
The patent changes the operational state parameters of the Geiger-mode avalanche photodiode dynamically during the detection frame. After detecting a reflection, the photodiode is quickly reset from its blinded state back to an active detection state, allowing it to detect multiple reflections within a single detection frame rather than being limited to one reflection per frame.
2Device complexity
If each pixel can only detect one reflection per detection frame, then the system is simpler to implement, but multiple reflections from the same optical pulse are missed, reducing data completeness
Solution Approach 1:
The patent implements preliminary resetting action immediately after each reflection detection. The reset circuitry is pre-configured to automatically reset the photodiode shortly after a detection event, ensuring the pixel is ready to detect subsequent reflections before the detection frame ends, thereby preventing information loss without requiring complex additional hardware.
3Reliability
If the pixel is reset at the start of the next detection frame, then the photodiode is properly prepared for the next frame, but the pixel remains blind during the current frame after the first detection, reducing scanning efficiency
Solution Approach 1:
The patent rushes through the reset process by implementing a rapid reset mechanism that occurs immediately after each reflection detection rather than waiting until the next frame begins. This allows the photodiode to quickly transition from a blinded state back to an active state, minimizing the time lost to resetting and maximizing the detection window within each frame.
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
Enables each pixel to detect multiple reflections within a single detection frame, preventing pixel blindness and improving data accuracy by allowing continuous range estimation without frame resets, thus mitigating object obscuration and enhancing scanning efficiency.
Implementation Method 1
each pixel includes a Geiger-mode avalanche photodiode for detecting reflections from a detection region
Data Source
AI summary
Disclosed are Geiger-mode avalanche-photodiode-based LiDAR systems and methods that interrogate a detection region with a periodic series of optical pulses whose reflections are detected via a receiver comprising multiple Geiger-mode avalanche-photodiode-based pixels. The pixels of the receiver are configured to asynchronously disarm and rearm after absorption of a reflection. As a result, each pixel can detect multiple reflections of the same optical pulse during a single detection frame whose duration is defined by the periodicity of the series of optical pulses. Furthermore, each pixel can store time-of-flight data for each of multiple reflections detected during a detection frame. Each individual pixel of the receiver, therefore, is not blinded and inoperative for the remainder of a detection frame once it detects a first reflection.