Optical Pulse Detection Device for Accurate Radiation Counting
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Solution Overview
Problem
Current radiation counting technologies using APD or SiPM arrays face issues with weak output signals, temperature fluctuations, high dark current, and external noise due to high electric fields, and require additional power supply circuits and amplification, leading to inaccurate radiation counting and susceptibility to environmental factors.
Innovation Solution
An optical pulse detection device with a pixel array unit, an AD converter, and a control circuit that converts output signals into digital values with gradation greater than 1 bit and performs error determination processing by comparing digital values with a threshold value to discard erroneous signals, improving radiation counting accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If APD or SiPM array is used instead of photomultiplier tube, then device size and weight are reduced and cost is lowered, but output signal becomes very weak and susceptibility to temperature fluctuations and external environment increases
Solution Approach 1:
The detector is divided into multiple pixels arranged in a two-dimensional lattice, with each pixel independently detecting optical pulses and generating digital values. This segmentation allows for localized error identification and exclusion, improving overall reliability while maintaining the compact APD/SiPM structure.
Solution Approach 2:
The control circuit performs error determination processing by comparing digital values from each pixel against threshold values, identifying and excluding erroneous signals. This feedback mechanism compensates for the inherent instability of APD/SiPM outputs, maintaining reliable radiation counting despite temperature fluctuations and environmental susceptibility.
2Measurement precision
If high electric field is applied to SiPM array to achieve detection, then dark current increases and floor noise becomes great due to after pulse and crosstalk
Solution Approach 1:
The control circuit performs error determination processing before final radiation counting, identifying and excluding digital values that exceed threshold values. This preliminary filtering removes the harmful effects of dark current and floor noise from the measurement results, maintaining measurement precision despite the presence of these noise sources.
Solution Approach 2:
The system uses multi-bit digital gradation (greater than 1 bit) to represent optical pulse signals, providing finer resolution and enabling more effective threshold-based error determination. This parameter change in signal representation allows for better discrimination between valid signals and noise, reducing the impact of dark current and floor noise.
3Power
If additional power supply circuit and amplifier are mounted for APD/SiPM configuration, then device complexity and susceptibility to external noise increase
Solution Approach 1:
The detection circuit integrates multiple functions including signal amplification, analog-to-digital conversion, and error determination processing within a unified structure. This merging eliminates the need for separate external power supply circuits and amplifiers, reducing device complexity while maintaining the necessary signal processing capabilities for reliable radiation counting.
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
The solution enables more accurate detection of weak pulse light and radiation counting by filtering out errors and reducing noise, enhancing the precision of radiation measurement.
Implementation Method 1
When one or more photons of radiation are incident to the scintillator, the scintillator emits light, and releases a pulse of visible light having the quantity of light that is proportional to the energy of radiation.
Implementation Method 2
Each of the pixels includes a photodiode that converts an incident minute optical pulse into an electrical signal.
Data Source
AI summary
The present technology relates to an optical pulse detection device, an optical pulse detection method, a radiation counter device, and a biological testing device which are capable of performing radiation counting in a more accurate manner. The optical pulse detection device includes a pixel array unit in which a plurality of pixels are arranged in a two-dimensional lattice shape, an AD converter that converts output signals of each of the pixels in the pixel array unit into digital values with gradation greater than 1 bit, and an output control circuit that performs error determination processing of comparing the digital value with a predetermined threshold value, and discarding a digital value, which is greater than the threshold value, among the digital values as an error. For example, the present technology is applicable to a radiation counter device, and the like.