Compact Photomultiplier with Vertical Electrode Stacking
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Solution Overview
Problem
Conventional photomultiplier tubes are large, heavy, fragile, expensive, and difficult to produce, limiting their effectiveness in detecting weak light across various applications.
Innovation Solution
A compact photomultiplier design featuring a substrate with strategically arranged electrodes, including a transparent electrode, electron ejector, and detector, where each electrode emits secondary electrons at an angle, facilitating electron multiplication and signal detection, and fabricated using micro-imprinting techniques with materials like MgO and bialkali compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional photomultiplier tube structure is used, then electron multiplication and light detection function is achieved, but device size is large and weight is heavy
Solution Approach 1:
The photomultiplier tube is divided into discrete functional modules: photocathode segment, multiple dynode segments (first, second, third electrodes), and collector segment. Each segment is positioned at specific heights above the substrate (photocathode at 50-150μm, dynodes at increasing intervals, collector at 50-150μm), creating a segmented electron multiplication path that reduces overall device volume while maintaining detection capability
Solution Approach 2:
The patent transitions from conventional lateral arrangement of components to a vertical stacking architecture where all functional elements are arranged perpendicular to the substrate plane. This dimensional reorganization compresses the device in the lateral direction while utilizing the vertical dimension for electron trajectory control, significantly reducing device footprint and weight
2Strength
If conventional photomultiplier tube structure is used, then electron multiplication function is achieved, but device is fragile
Solution Approach 1:
Multiple functional components (substrate, electrodes, insulating layers, reflective layers) are merged into a single integrated vertical stack. All components are anchored to or positioned relative to the substrate, creating a unified structure that eliminates fragile connections between separate assemblies and improves overall mechanical robustness while preserving electron multiplication function
Solution Approach 2:
The patent employs thin film structures for electrodes and insulating layers deposited on the substrate. These thin films are mechanically supported by the substrate and underlying layers, providing the necessary electrical functionality while being mechanically flexible and resistant to fracture, thereby improving device robustness
3Ease of manufacture
If conventional photomultiplier tube structure is used, then light detection capability is achieved, but production difficulty increases
Solution Approach 1:
The substrate is prepared in advance with pre-defined positioning features, support structures, and alignment marks before electrode deposition. Insulating layers and reflective layers are also pre-deposited with predetermined thicknesses and positions. This preliminary preparation establishes a rigid fabrication framework that guides subsequent steps, reducing the need for high-precision adjustments during assembly and simplifying the overall manufacturing process
4Reliability
If conventional photomultiplier tube structure is used, then electron multiplication is achieved, but device cost increases
Solution Approach 1:
The patent optimizes critical parameters including electrode spacing (50-150μm for photocathode and collector, variable for dynodes), layer thicknesses, and material compositions to achieve high detection sensitivity. By carefully controlling these parameters during fabrication, the device achieves superior performance that reduces the need for post-manufacturing calibration and testing, thereby lowering overall production costs despite the precision required
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 design enhances light detection sensitivity, reduces size and weight, and simplifies production, enabling effective detection of weak light across applications such as night vision and medical imaging.
Implementation Method 1
Light entering the PMT 100 and incident on the photocathode 102 causes photoelectrons to be emitted by the photocathode 102, as a consequence of the photoelectric effect
Implementation Method 2
The primary electrons impinge on the successive dynodes 104, causing electron multiplication by secondary emission
Data Source
AI summary
Disclosed herein is a photomultiplier comprising: an electron ejector; a detector; a substrate; and a first electrode in the substrate; a second electrode in the substrate; a third electrode in the substrate; wherein each of the first, second and third electrodes comprises a flat or curved surface at an angle to a normal direction of the substrate; wherein each of the first, second and third electrodes comprises a first end and a second end, the first end being closer to the electron ejector than the second end; wherein the first, second and third electrodes are spatially arranged such that the second ends of the first, second and third electrode are on a same plane, or such that a plane the second ends of the first and third electrodes are on crosses the second electrode.