Wavelength-Shifting Sheet Scintillation Detector for Uniform Light Collection
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Solution Overview
Problem
Conventional scintillation detectors suffer from low light collection efficiency, non-uniform response, and high manufacturing costs due to the trade-off between transmission and reflection coefficients, which are exacerbated in handheld flying spot transmission imaging systems, leading to non-uniform image quality and increased weight and size.
Innovation Solution
The use of a wavelength-shifting sheet (WSS) detector, where a scintillator screen is optically coupled with a wavelength-shifting sheet that collects light at its edges and transmits it to photodetectors, reducing the need for multiple fibers and simplifying the manufacturing process, thereby improving spatial uniformity and reducing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If scintillation screens are designed to maximize light transmission coefficient, then light transmission is improved, but light collection efficiency deteriorates because reflection coefficient must also be large for multiple reflections to reach photodetector
Solution Approach 1:
A wavelength-shifting material layer is introduced as an intermediary between the scintillation screen and the photodetector. This layer converts the UV light emitted by the scintillator into visible light, which can then be efficiently transmitted through the wavelength-shifting material to the photodetector, resolving the conflict between transmission and reflection requirements
Solution Approach 2:
The patent changes the wavelength parameter of the light by using wavelength-shifting materials. The scintillator emits UV light, which is then converted to visible light through the wavelength-shifting material, allowing optimization of transmission properties at the new wavelength while maintaining efficient light collection
2Measurement precision
If conventional fiber-coupled scintillation detectors are used to improve light collection, then spatial resolution is improved, but device complexity and manufacturing cost increase due to multiple fibers and complex assembly
Solution Approach 1:
Multiple individual optical fibers are merged into a single wavelength-shifting material layer that spans the entire detector area. This integration maintains the spatial resolution capabilities of fiber-coupled systems while eliminating the complexity of handling and assembling multiple individual fibers
Solution Approach 2:
The patent creates a distributed copy of the wavelength-shifting function across the entire detector surface through the wavelength-shifting material layer, replacing the need for multiple discrete fiber copies. This maintains light collection efficiency while simplifying the overall structure
3Reliability
If conventional backscatter detectors are used, then detection capability is maintained, but weight and size increase due to larger photodetector area requirements
Solution Approach 1:
The patent changes the wavelength parameter through wavelength-shifting materials, which enables more efficient light transmission to smaller photodetectors. This parameter change allows maintaining detection capability while reducing the required photodetector area, weight, and size
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 WSS detector achieves improved spatial uniformity and reduced manufacturing costs while maintaining efficient light collection, enabling high-quality imaging in handheld flying spot transmission systems.
Implementation Method 1
a light-tight box 102 is lined with scintillating screens 103 where incident X-ray radiation 101 is converted to scintillation light
Implementation Method 2
wavelength-shifting sheet (WSS), which shifts light absorbed from the scintillator screen
Implementation Method 3
The longer wavelength light is emitted isotropically in the fiber material. Total internal reflection traps a fraction of that light and conducts it over long distances with relatively low loss
Implementation Method 4
wavelength-shifting fiber or sheet at the edge of the wavelength shifting sheet that is configured to collect a plurality of first shifted rays and transmit the collected rays to a photodetector
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
The present specification describes an X-ray detector that includes at least one scintillator screen for absorbing incident X rays and emitting corresponding light rays, a wavelength shifting sheet (WSS) coupled with the at least one scintillator screen for shifting the emitted light rays, at least one wavelength shifting fiber (W SF) coupled with at least one edge of the WSS for collecting the shifted light rays, and a photodetector for detecting the collected light rays.