Photon Counting Linear Dynamic Range Extension
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Solution Overview
Problem
Existing photon counting methods face nonlinearities at high photon count rates, limiting their dynamic range and requiring complex calibration and multiple detector approaches, which lead to sensitivity mismatches and accuracy issues.
Innovation Solution
A method that synchronizes analog-to-digital conversion with discriminator-based event counting, using binomial and Poisson distributions to estimate the number of discrete generating events, extending the linear dynamic range by determining a Poisson-weighted detector response function and combining count-type and average signal-type data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photon counting is used to detect low intensity light, then sensitivity is improved, but nonlinearity occurs at high photon count rates
Solution Approach 1:
The patent dynamically switches between photon counting mode (for low light levels) and analog integration mode (for high light levels) based on the detected signal intensity. This dynamic adaptation allows the system to maintain both high sensitivity at low levels and linear response at high levels, resolving the contradiction between sensitivity and linearity.
Solution Approach 2:
The system changes the operating parameter of the detector by adjusting the discriminator threshold and switching between counting and integration modes. By varying these parameters based on signal strength, the system achieves both high sensitivity (through counting at low levels) and maintained linearity (through integration at high levels).
2Reliability
If multiple photo detectors with beam splitters are used to extend dynamic range, then linear response range is improved, but device complexity increases
Solution Approach 1:
The patent makes a single detector perform multiple functions by switching between photon counting mode and analog integration mode. This multi-functionality eliminates the need for multiple detectors and beam splitters, achieving extended dynamic range while reducing device complexity.
Solution Approach 2:
The system merges photon counting detection and analog integration detection into a single unified detection channel. By combining these two approaches in one detector and switching between them, the system achieves the extended linear dynamic range of multiple detectors without the complexity of multiple detector configurations.
3Reliability
If multiple detectors are combined to extend dynamic range, then measurement range is improved, but noise contribution increases
Solution Approach 1:
The system merges counting and integration detection into a single detector channel, avoiding the additive noise that would result from combining multiple independent detectors. This unified approach extends measurement range while maintaining lower noise levels compared to multi-detector systems.
Data Source
AI summary
A method and apparatus for photon, ion or particle counting described that provides seven orders of magnitude of linear dynamic range (LDR) for a single detector. By explicitly considering the log-normal probability distribution in voltage transients as a function of the number of photons, ions or particles present, the binomial distribution of observed counts for a given threshold, the mean number of photons, ions or particles can be determined well beyond the conventional limit.