Event-triggered imaging pixels for 3D range data
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Solution Overview
Problem
Conventional imaging systems for three-dimensional range and intensity data, such as LiDAR, face limitations in capturing high-resolution images through obscurants like smoke or haze, as they typically require synchronized exposure windows and binary return signals, which restrict their ability to gather detailed information in a single exposure.
Innovation Solution
The proposed solution involves an imaging pixel circuit with a photodetector, input buffer, control device, and sampling circuit, where a comparator and switch allow for event-triggered sampling of high-frequency charge signals, enabling asynchronous detection and storage of charge data, even if signals arrive at different times, thus allowing for high-resolution image overlay with 3D range information in a single exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional LiDAR systems use synchronized exposure windows for range gating, then range information can be obtained, but the ability to capture detailed information asynchronously is restricted
Solution Approach 1:
The patent divides the imaging system into independent pixel-level units, each with its own comparator and switch circuitry. This segmentation allows each pixel to operate independently with event-triggered sampling, enabling asynchronous detection while maintaining precise range measurement through time-stamped photon arrival detection.
Solution Approach 2:
The system transitions from static synchronized exposure windows to dynamic event-triggered sampling. The comparator continuously monitors photon arrival signals and dynamically opens the switch only when events occur, allowing the system to adapt to varying signal conditions and capture asynchronous events without being constrained by fixed exposure timing.
2Reliability
If conventional systems capture images through obscurants with fixed exposure timing, then range gating is achieved, but signal-to-noise ratio deteriorates due to inability to selectively sample events
Solution Approach 1:
The comparator provides continuous feedback monitoring of photon arrival signals at each pixel. When the signal exceeds a threshold, it triggers the switch to sample and store the event. This feedback mechanism selectively captures valid photon events while rejecting noise, improving signal-to-noise ratio and reliability for imaging through obscurants.
Solution Approach 2:
Each pixel circuit autonomously detects and samples its own photon arrival events without requiring external synchronization. The self-service capability allows pixels to independently identify and record valid signals, maintaining high signal-to-noise ratio even when imaging through obscurants with varying transmission characteristics.
3Device complexity
If synchronized exposure windows are used for all pixels, then system control is simplified, but detailed 3D information and high-resolution images cannot be captured simultaneously in a single exposure
Solution Approach 1:
The system segments control functions to the pixel level, with each pixel having its own event-triggered sampling circuitry. This segmentation enables simultaneous asynchronous operation of all pixels, capturing detailed 3D range information and high-resolution image data in a single exposure without requiring complex centralized synchronization.
Solution Approach 2:
The comparator and switch circuitry act as intermediary elements between the photodetector and charge storage device. These intermediaries automatically trigger sampling based on local event detection, eliminating the need for complex external synchronization while preserving both 3D range and image detail through time-stamped event recording.
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 superior imaging capabilities, allowing penetration through obscurants while capturing detailed 3D range information and high-resolution images simultaneously, with improved signal-to-noise ratio and the ability to create 'painted' 3D maps with a single illumination pulse.
Implementation Method 1
a photodetector for generating a charge signal in response to an excitation signal
Data Source
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AI summary
An imaging pixel includes a photodetector (102) for generating a charge signal, an input buffer (104), a control device (106), and a switch (110). The input buffer is connected to the photodetector for amplifying the charge signal. The control device is connected to the photodetector and the input buffer to separate high-frequency charge signals from low frequency charge signals. The switch is operably connected to the input buffer for sampling of high-frequency charge signals in a charge storage device triggered by amplitude of high-frequency charge signals provided by the input buffer.