Compact Photomultiplier Tube with Vertical Electrodes
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Solution Overview
Problem
Conventional photomultiplier tubes (PMTs) are large, heavy, fragile, expensive, and difficult to produce, limiting their effectiveness in detecting low-intensity light across various applications.
Innovation Solution
A compact PMT design featuring a series of vertical electrodes between an electron ejector and detector, with each electrode configured for secondary electron emission, and a transparent electrode to drive primary electrons toward the detector, along with a method involving substrate etching and electroplating for microfabrication, enabling efficient photon detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PMT structure is used, then photon detection capability is achieved, but device size becomes large and weight increases
Solution Approach 1:
The PMT is segmented into three functional layers (electron ejector, vertical electrodes, detector) stacked vertically, with each layer performing a specific function. This segmentation enables compact integration while maintaining detection capability, reducing overall device size and weight compared to conventional horizontal arrangements.
Solution Approach 2:
The patent transitions from conventional horizontal electron multiplication paths to a vertical stacking architecture. Electrons are accelerated vertically through the layered structure, utilizing the vertical dimension for electron multiplication instead of horizontal propagation, thereby compacting the device in the horizontal plane and reducing overall footprint and weight.
2Reliability
If conventional PMT structure is used, then photon detection is enabled, but device fragility increases
Solution Approach 1:
Dividing the PMT into discrete functional layers (electron ejector, vertical electrodes, detector) allows each component to be optimized for mechanical strength independently. The stacked configuration distributes mechanical stresses across multiple small interfaces rather than concentrating them in large vacuum envelopes, improving overall device robustness.
Solution Approach 2:
The patent employs thin-film fabrication techniques for the vertical electrodes and electron ejector, creating a compact structure that is inherently more mechanically robust. The layered architecture with potential flexible substrates replaces fragile large-volume vacuum tubes with solid-state or semi-solid-state components that resist shock and vibration.
3Reliability
If conventional PMT structure is used, then detection function is achieved, but manufacturing complexity increases
Solution Approach 1:
The PMT is divided into three independently fabricable layers that can be manufactured separately using standard semiconductor and thin-film techniques, then assembled through bonding. This modular segmentation enables parallel production of components and simplifies quality control compared to monolithic conventional PMT fabrication.
Solution Approach 2:
The patent replaces conventional vacuum tube mechanics with solid-state thin-film fabrication and bonding processes. The vertical electrodes are deposited as thin films rather than assembled as mechanical components, and electron multiplication is achieved through electric fields in solid-state structures rather than mechanical vacuum envelope configurations, dramatically simplifying manufacturing.
4Reliability
If conventional PMT structure is used, then photon detection is achieved, but device cost increases
Solution Approach 1:
The patent replaces expensive vacuum tube manufacturing with cost-effective thin-film deposition and bonding processes. The vertical electrodes can be fabricated using standard semiconductor manufacturing techniques (sputtering, evaporation, CVD) that are highly scalable and cost-efficient, eliminating the need for expensive vacuum sealing and assembly operations required by conventional PMTs.
Solution Approach 2:
The patent changes the fundamental fabrication parameters from vacuum-based mechanical assembly to solid-state thin-film deposition. This parameter change enables the use of automated, high-volume manufacturing processes that significantly reduce per-unit costs while maintaining detection performance.
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 new PMT design enhances sensitivity and spatial resolution, allowing for the detection of low-intensity light with improved reliability and reduced production complexity, suitable for applications in nuclear physics, astronomy, and medical imaging.
Implementation Method 1
Light entering the tube 100 and incident on the photocathode 102 causes electrons to be emitted by the photocathode 102, as a consequence of the photoelectric effect
Implementation Method 2
each of the vertical electrodes is configured for emitting secondary electrons in response to incident electrons
Implementation Method 3
a detector configured for collecting electrons and providing an output signal representative of the incident photon
Data Source
AI summary
Disclosed herein is a photomultiplier tube (PMT) comprising: an electron ejector configured for emitting primary electrons in response to an incident photon; a detector configured for collecting electrons and providing an output signal representative of the incident photon; and a series of electrodes between the electron ejector and the detector, wherein each of the electrodes is configured for emitting secondary electrons in response to incident electrons, and each of the electrodes includes a bi-metal arc-shaped sheet.