Prism-Based Optical Path Separation in Radiation Image Detection
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Solution Overview
Problem
Radiation image detecting devices face the challenge of preventing photodetecting elements from detecting excitation light, which can lead to interference and inaccurate signal detection.
Innovation Solution
A radiation image detecting device is designed with a prism that directs excitation light away from the photodetecting element, using inclined surfaces to ensure that fluorescence light is detected while excitation light is not, utilizing a configuration where the photodetecting element is positioned to receive fluorescence light from specific surfaces of the prism, thereby preventing excitation light from entering the photodetecting element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the photodetecting element is positioned to detect fluorescence light from the recording medium, then the detection sensitivity for fluorescence light is improved, but the photodetecting element may also detect excitation light which causes interference and reduces measurement precision
Solution Approach 1:
The optical path is segmented into distinct channels: one for excitation light transmission and another for fluorescence light detection. The prism divides the optical path such that excitation light and fluorescence light travel through different spatial routes, preventing the photodetecting element from detecting excitation light while maintaining fluorescence light detection capability
Solution Approach 2:
The prism acts as an intermediary optical element that separates excitation light from fluorescence light. By positioning the prism on the optical path and configuring its inclined surfaces, it redirects excitation light away from the photodetecting element while allowing fluorescence light to reach the detector, thus mediating between the light source and detector to eliminate interference
2Device complexity
If a simple optical path is used without additional optical elements, then the device complexity is reduced, but it becomes difficult to prevent excitation light from entering the photodetecting element
Solution Approach 1:
The prism serves multiple functions simultaneously: it transmits excitation light to the recording medium, redirects reflected excitation light away from the photodetecting element, and transmits fluorescence light from the recording medium to the photodetecting element. This multi-functionality achieves effective excitation light rejection without requiring additional separate optical components
Solution Approach 2:
The prism utilizes the natural reflection properties of its inclined surfaces to automatically redirect excitation light away from the photodetecting element. The geometric configuration of the prism itself provides the necessary optical separation function without requiring additional active control mechanisms or complex optical assemblies
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 prevents the photodetecting element from detecting excitation light, minimizing interference and ensuring accurate detection of fluorescence light, even when avalanche photodiodes are used in Geiger mode.
Implementation Method 1
The prism has, as surface thereof, a first face that is opposed to the recording medium and a second face and a third face that are inclined relative to the first face, and is disposed so that the excitation light incident through the second face propagates inside and is output from the first face
Implementation Method 2
The prism is disposed so that reflection from the recording medium incident through the first face propagates inside and is output from the third face or reflected by the third face and output from the second face
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
A radiation image detecting device 20 includes a photodetecting element 10 that detects fluorescence light, and a prism 5 that is disposed on an optical path of excitation light EL traveling toward an imaging plate IP and between the photodetecting element 10 and the imaging plate IP. The prism 5 includes, as surface thereof, a side face 5c that is opposed to the imaging plate IP, and a side face 5a and a side face 5b that are inclined relative to the side face 5c. The prism 5 is disposed so that the excitation light EL incident through the side face 5a propagates inside and is output from the side face 5c and so that reflection from the imaging plate IP incident through the side face 5c propagates inside and is output from the side face 5b. The photodetecting element 10 is disposed so as to be opposed to a region different from a region where the reflection from the imaging plate IP is output, in the surface of the prism 5.