Detector Pulse Pile-Up Compensation in TCSPC

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Solution Overview

Problem

Time-correlated single-photon counting measurements are affected by detector pulse pile-up, leading to artefacts in decay histograms, particularly at high count rates, which prolong measurement times and distort fluorescence lifetime estimates.

Innovation Solution

A method that estimates and corrects for detector pulse pile-up by fitting an adjusted model-function to the decay histogram, accounting for the probability of overlapping pulses, allowing for higher count rates and shorter measurement times without distorting the results.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the count rate is increased to reduce measurement time, then productivity improves, but detector pulse pile-up effects occur causing measurement precision to deteriorate

Engineering Contradiction:
Improvemeasurement speedVSAvoidfluorescence lifetime estimation accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent converts the harmful detector pulse pile-up effect into a beneficial correction factor. By modeling the pile-up effect mathematically and applying a correction algorithm to the decay histogram, the system can now operate at high count rates while maintaining accurate fluorescence lifetime measurements. The harmful distortion caused by overlapping pulses is transformed into a correctable artifact that actually enables faster measurements.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the operational parameter of count rate from a limiting factor to an optimized parameter. By introducing correction algorithms, the system can now operate at count rates 10-100 times higher than previously possible, fundamentally changing the performance characteristics of the measurement system while maintaining accuracy through mathematical compensation.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the count rate is kept low to avoid detector pulse pile-up, then measurement precision is maintained, but productivity deteriorates due to prolonged measurement times

Engineering Contradiction:
Improvefluorescence lifetime estimation accuracyVSAvoidmeasurement speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

Instead of avoiding the harmful pile-up effect by limiting count rate, the patent embraces it and converts it into a correctable phenomenon. The systematic distortion introduced by high count rates becomes a known artifact that can be mathematically reversed, allowing the system to operate at optimal speeds while recovering accurate measurements through correction algorithms.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent applies preliminary correction factors to the decay histogram before final analysis. By pre-compensating for the expected pile-up effects based on the measured count rate and detector characteristics, the system prepares the data in advance to withstand high count rate operation without losing measurement accuracy.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If dead time of TCSPC-electronics is reduced to enable higher count rates, then productivity improves, but device complexity increases

Engineering Contradiction:
Improvecount rate capabilityVSAvoidelectronics complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces the need for ultra-fast electronics with a computational solution. Instead of reducing hardware dead time through complex electronic design, the system uses software-based correction algorithms that run on standard processors, substituting mechanical/electronic optimization with computational compensation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a computational intermediary layer between the detector and the measurement analysis. This software intermediary processes the raw decay histogram, applies correction factors for pile-up effects, and outputs corrected measurements, mediating between the high count rate data acquisition and the final accurate results without requiring complex hardware modifications.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 increases the applicable count rate interval by a factor of over 10, significantly reducing measurement time while maintaining accurate fluorescence lifetime estimates, even at high count rates, by accounting for detector pulse pile-up effects.

Implementation Method 1

detection of photons with a detector, which converts the detected photons into corresponding electrical pulses

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

measure for example a fluorescence lifetime of a compound is to perform time-domain-based single-photon counting measurements

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Implementation Method 3

fluorescence lifetime imaging (FLIM) measurements on scanning microscopes or fast (on-line) monitoring of fluorescence lifetimes in spectroscopy

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Data Source

PatentEP3431967B1Method for compensating detector pulse pile-up effects in time-correlated single-photon counting applications
Publication Date: 2023.06.07 PICOQUANT INNOVATIONS
  • EP3431967B1 patent drawingFigure 1a)~1c)
  • EP3431967B1 patent drawingFigure 2
  • EP3431967B1 patent drawingFigure 3

AI summary

The invention relates to a method for estimating and correcting for detector pulse pile-up effects in time-correlated single-photon counting applications, particularly in decay histograms (1, 2), comprising the steps of: - Acquiring a decay histogram (1, 2) from a time-correlated single-photon counting measurement, wherein said measurement comprises the detection of photons (9) with a detector, the detector converting the detected photons (9) into corresponding electrical pulses (8) forming a sequence of electrical pulses, wherein the sequence of electrical pulses (8) comprises electric pulses (8a) that are spaced apart by a time interval (11) that is shorter than a smallest resolvable interval (dt) of a recording device, wherein the recording device registers the electric pulses (8) from the detector, - Estimating a probability of occurrence (pi) of electric pulses exhibiting a spacing longer than the smallest resolvable interval for each channel of the decay histogram (1, 2), - Fitting an adjusted model-function (4) to the decay histogram (1, 2), wherein the adjusted model-function (4) comprises an unadjusted model-function (3) adjusted for each channel of the decay histogram (1, 2) with the estimated probability of occurrence (pi) for the corresponding channel.