Electron Microscope X-ray Detector Magnetic Field Shielding
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Solution Overview
Problem
The use of microcalorimeters with SQUID current detecting circuits in electron microscopes is hindered by strong DC biases from the objective lens magnetic field, leading to saturation and reduced elemental analysis performance, as SQUID devices are sensitive to intense magnetic fields.
Innovation Solution
Positioning the X-ray detector in a region with a magnetic field intensity weaker than the critical value for the thermal insulation shield, and using a magnetic field shield or X-ray optical system to transmit X-rays away from the objective lens's magnetic influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the detection device is disposed close to the electron-beam irradiating position, then X-ray yields are improved, but the SQUID current detecting circuit is saturated due to the objective lens magnetic field
Solution Approach 1:
An X-ray lens is introduced as an intermediary component between the sample and the detection device. The X-ray lens transmits X-rays generated from the sample to the detection device while allowing the detection device to be positioned in a region with weaker magnetic field intensity, thus preventing SQUID circuit saturation while maintaining high X-ray yields
Solution Approach 2:
The detection device is repositioned from the conventional location close to the sample to a different spatial dimension - specifically, a position where the magnetic field intensity from the objective lens is weaker than the critical magnetic field. This dimensional repositioning allows the detection device to operate reliably while still receiving sufficient X-rays through the X-ray lens
2Reliability
If the distance between the sample and the detection device is extended to avoid the objective lens magnetic field, then the SQUID circuit saturation is avoided, but X-ray yields are reduced
Solution Approach 1:
The X-ray lens serves as a mediator that enables the detection device to be positioned far from the sample (avoiding magnetic field saturation) while still efficiently collecting X-rays. The lens focuses and transmits X-rays over the extended distance, compensating for the reduced solid angle of collection
3Reliability
If an X-ray lens is disposed between the sample and the detection device, then the detection device can be positioned away from the magnetic field, but the device complexity increases
Solution Approach 1:
The X-ray lens is integrated into the existing electron microscope system, serving multiple functions: it transmits X-rays from the sample to the detection device, enables the detection device to be positioned in a low magnetic field region, and maintains compatibility with the electron beam irradiation system. This multi-functionality justifies the added complexity
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 approach allows for high-resolution image observation and high-energy-resolution X-ray analysis without reducing X-ray yields, enabling the effective use of microcalorimeters in electron microscopes with strong magnetic fields.
Implementation Method 1
a thermal insulation shield for a superconducting transition-edge sensor or a microcalorimeter
Implementation Method 2
an X-ray lens is disposed between a sample and a detection device
Implementation Method 3
an X-ray lens is disposed between a sample and a detection device
Implementation Method 4
a superconducting quantum interference device (SQUID) installed in a cryogenic environment
Implementation Method 5
a microcalorimeter (referred to as a TES type EDS) that has a higher energy-resolution than the semiconductor detection device and uses a transition edge sensor (TES) as the detection device
Data Source
AI summary
The objective of the present invention is to simultaneously achieve image observations at a high resolution using an electron microscope, and X-ray analysis at a high energy-resolution using a microcalorimeter. An X-ray detector is disposed at a position where the intensity of the magnetic field from an objective lens is weaker than the critical magnetic field of a material used in a thermal insulation shield for a superconducting transition-edge sensor or a microcalorimeter. In addition, an optical system for transmitting X-rays to the detector is inserted between a sample and the detector. Alternatively, a magnetic field shield for shielding the X-ray detector is used.