Two-Dimensional Photon Counting Element Signal Processing

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Solution Overview

Problem

Two-dimensional photon counting elements face challenges in accurately counting photons when carriers are dispersedly collected across multiple pixel electrode portions, leading to double counting and counting loss, particularly due to thermal diffusion and repulsion, and require complex threshold adjustments to prevent such issues.

Innovation Solution

A two-dimensional photon counting element with a counting circuit that includes a signal generating unit, an adding unit, a carrier input pattern discriminating unit, and a counting unit, which discriminates carrier input patterns against predefined patterns to accurately count photons even when carriers are dispersed, using a specific pixel electrode group and peripheral electrode portions to determine photon incidence and prevent double counting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If carriers are collected in multiple pixel electrode portions due to thermal diffusion and repulsion, then the photon detection coverage is improved, but double counting occurs and measurement precision deteriorates

Engineering Contradiction:
Improvedetection coverageVSAvoidphoton counting accuracy
Core Design Contradiction:
Area of stationary objectVSMeasurement precision

Solution Approach 1:

The invention segments the pixel array into a center pixel and surrounding peripheral pixels, with each pixel having an independent counting circuit. The center pixel's counting circuit receives carrier signals from both the center pixel electrode portion and peripheral pixel electrode portions, allowing it to detect photons that generate carriers distributed across multiple pixels. This segmentation enables comprehensive detection coverage while maintaining accurate counting through the specific configuration where peripheral pixel signals are routed to the center pixel's counting circuit.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If a threshold is set to prevent double counting, then measurement precision is improved, but the device complexity increases due to complex signal processing requirements

Engineering Contradiction:
Improvephoton counting accuracyVSAvoidsignal processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention employs a self-service mechanism where the counting circuit automatically determines whether to increment the count value based on comparing the input signal magnitude against a threshold, without requiring external intervention or complex processing. The counting circuit receives the input signal from the signal generating unit, compares it with the threshold value, and autonomously decides whether to increment the count. This self-service approach simplifies the overall system by eliminating the need for complex external signal processing while maintaining accurate photon counting.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If separate processing is implemented to prevent double count, then measurement precision is improved, but device complexity increases significantly

Engineering Contradiction:
Improvephoton counting accuracyVSAvoidinput signal processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention merges the detection functions of the center pixel and peripheral pixels into a single counting circuit. Instead of implementing separate processing for each pixel to prevent double counting, the design combines the carrier signals from both center and peripheral pixel electrode portions into one counting circuit. This merging approach simplifies the system architecture by eliminating the need for multiple independent processing paths while effectively preventing double counting through the unified threshold-based decision mechanism.

Inventive Principle:
Principle #5Merging (Combining)

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 configuration effectively suppresses double counting and reduces counting loss, allowing for precise determination of photon incidence positions without complex signal processing, even in cases of charge sharing across multiple pixels.

Implementation Method 1

a plate-shaped or layered converting unit that converts a photon to a carrier such as charge

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentEP3082332B1Two-dimensional photon counting element
Publication Date: 2018.09.19 HAMAMATSU PHOTONICS KK
  • EP3082332B1 patent drawingFigure 1
  • EP3082332B1 patent drawingFigure 2(a)~2(b)
  • EP3082332B1 patent drawingFigure 3

AI summary

An adding unit 53 adds an input signal generated in a signal generating unit 51 connected to a specific pixel electrode portion out of pixel electrode portions arranged around a certain pixel electrode portion to an input signal generated in a signal generating unit 51 connected to the certain pixel electrode portion. A carrier input pattern discriminating unit 56 discriminates whether a carrier input pattern coincides with any one of a plurality of discrimination patterns, and the carrier input pattern indicates, per the pixel electrode portion, presence of any carrier received in the certain pixel electrode portion and the pixel electrode portions arranged around the certain pixel electrode portion. The counting unit 57 increments the number of photons in the case where the carrier input pattern discriminating unit 56 discriminates that the carrier input pattern coincides with any one of the plurality of discrimination patterns and further the input signal output from the adding unit 53 after addition has a value exceeding a predetermined threshold.