Intimately-Coupled Scintillator-SiPM Electron Detector
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Solution Overview
Problem
Current electron detectors in electron microscopes are large, require high voltage, and occupy valuable access ports, limiting their placement and efficiency, especially in scanning electron microscopes where they compete with other analytical tools for space and cannot achieve high resolution due to the need for light guides that reduce light collection efficiency.
Innovation Solution
The development of an electron detector using intimately-coupled scintillator-silicon photomultiplier combinations that eliminate the need for light guides, allowing for smaller, low-voltage operation, and enabling multiple detectors to be positioned within the electron column or sample chamber, thereby increasing available ports and improving image resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If light guides are used to connect scintillators to photomultipliers, then the detector can be placed outside the vacuum chamber, but light collection efficiency is reduced and device size increases
Solution Approach 1:
The patent merges the scintillator and photomultiplier into a single integrated assembly where the scintillator is directly coupled to the photomultiplier's photocathode. This eliminates the need for separate light guides and intermediate optical paths, thereby maximizing light collection efficiency and simplifying the overall detector structure. The direct coupling ensures that photons generated in the scintillator are immediately detected by the photomultiplier without losses from reflection, absorption, or scattering in light guide materials.
Solution Approach 2:
The invention extracts and eliminates the light guide component from the traditional detector architecture. By removing this intermediate element, the system achieves direct optical coupling between the scintillator and photomultiplier, eliminating the associated light losses and structural complexity while maintaining the ability to place detectors within the vacuum chamber.
2Measurement precision
If traditional photomultipliers are used, then high detection sensitivity is achieved, but high voltage requirements and large size limit placement flexibility
Solution Approach 1:
The patent changes the operating voltage parameter from the traditional high voltage (thousands of volts) required by conventional photomultipliers to low voltage operation (tens to hundreds of volts) enabled by silicon photomultipliers. This parameter change maintains high detection sensitivity while dramatically improving placement flexibility, allowing detectors to be positioned within the electron column or sample chamber where space is constrained and high voltage would be problematic.
Solution Approach 2:
The invention substitutes the traditional vacuum tube photomultiplier with a solid-state silicon photomultiplier. This replacement eliminates the need for high voltage power supplies and complex vacuum sealing requirements, enabling compact, flexible detector designs that can be integrated directly into the microscope column or chamber environment.
3Productivity
If multiple detectors are placed in the sample chamber, then imaging capability is improved, but access ports are limited and space is constrained
Solution Approach 1:
The patent implements a nested arrangement where scintillators are positioned within or adjacent to the electron column structure, and photomultipliers are coupled directly to them in a compact configuration. This nesting allows multiple detector assemblies to be accommodated within the limited space of the sample chamber or electron column without requiring separate access ports for each detector, thereby improving imaging capability while respecting spatial constraints.
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 solution enables high-resolution imaging with increased port availability, reduced complexity and cost, and improved efficiency by using directly connected scintillator-SiPM pairs that enhance light collection and operate at lower voltages, allowing for faster scanning rates and more flexible detector placement.
Implementation Method 1
a first scintillator and a first silicon photomultiplier directly connected to one another such that the first silicon photomultiplier is directly receiving photons emitted by the first scintillator
Implementation Method 2
a first silicon photomultiplier directly connected to one another such that the first silicon photomultiplier is directly receiving photons emitted by the first scintillator
Data Source
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AI summary
An electron detector includes a plurality of assemblies, the plurality of assemblies including a first assembly having a first SiPM and a first scintillator made of a first scintillator material directly connected to an active light sensing surface of the first SiPM, and a second assembly having a second SiPM and a second scintillator made of a second scintillator material directly connected to an active light sensing surface of the second SiPM, wherein the first scintillator material and the second scintillator material are different than one another. Alternatively, an electron detector includes an assembly including an SiPM and a scintillator member having a front surface and a back surface, the scintillator member being a film of a scintillator material directly deposited on to an active light sensing surface of the SiPM.