SPD Array Persistence Filtering for False Photon Rejection
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Solution Overview
Problem
High-speed imaging systems face challenges in accurately distinguishing between genuine photon detections and false positives caused by thermal noise and ambient light, leading to inefficiencies in processing speed and resolution, especially with single-photon detectors like SPADs.
Innovation Solution
Implementing a persistence condition where detection signals must be consistently positive across multiple observation windows to confirm genuine photon incidences, filtering out false positives and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single-photon detectors (SPDs) are used to increase photosensitivity for capturing limited photons, then detection sensitivity is improved, but false positives increase due to thermal noise and ambient light
Solution Approach 1:
The patent applies preliminary action by requiring multiple detection events (at least two photons) before generating a valid detection signal. This pre-condition filtering eliminates single-photon false positives from thermal noise and ambient light while preserving genuine multi-photon signals from reflected laser light, thus resolving the contradiction between detection sensitivity and false positive rate
Solution Approach 2:
The patent converts the harmful effect of high photosensitivity (which causes thermal noise and ambient light detections) into a beneficial feature. By requiring multiple photon detections, the system leverages the high sensitivity to detect genuine multi-photon events while the statistical unlikelihood of multiple simultaneous false positives transforms the noise problem into a reliable detection mechanism
2Productivity
If the processing time is reduced to achieve high voxel rates (tens or hundreds of millions per second), then imaging speed is improved, but detection accuracy deteriorates due to insufficient photons captured
Solution Approach 1:
The patent applies periodic action through time-binned photon detection, where photons are detected and accumulated in discrete time bins corresponding to the laser scanning periods. This allows the system to process detections at high speed (one bin per scan position) while accumulating sufficient photon statistics within each bin to maintain detection accuracy, resolving the contradiction between voxel rate and detection accuracy
3Manufacturing precision
If pixel size is reduced to increase spatial resolution, then spatial resolution is improved, but photosensitivity deteriorates due to limited spatial window
Solution Approach 1:
The patent applies merging by combining signals from multiple detector pixels through coincidence detection. When photons from the same laser pulse are detected in coincidence across multiple pixels, their signals are merged to form a single valid detection. This allows the use of smaller pixels for high spatial resolution while maintaining effective photosensitivity through signal combination, resolving the contradiction between spatial resolution and photosensitivity
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 significantly reduces false positives, enhancing the speed and accuracy of high-speed imaging by ensuring only confirmed photon incidences are processed, thereby improving voxel rate and spatial resolution.
Implementation Method 1
single-photon detectors (SPDs), whereby false positives are filtered out of the results
Data Source
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AI summary
The present invention relates to a system, detector element and method for high-speed imaging with SPD arrays, and a calibration routine for SPD arrays.