Electron Beam Calibration via X-Ray Substrate Detection
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Solution Overview
Problem
Current methods for calibrating electron beams in freeform fabrication or additive manufacturing are time-consuming, require high beam power, can damage materials, and are insensitive to material deposition, with a lack of straightforward relationship between glow and beam power.
Innovation Solution
A method using a patterned aperture resolver and modulator to scan an electron beam, detecting X-rays with a detector to map and adjust the beam's position, size, and shape, allowing for calibration at any time without material damage and across various beam powers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical calibration using metal glow is used, then electron beam calibration can be performed, but it is time-consuming and requires high beam power
Solution Approach 1:
The patent introduces a substrate as an intermediary medium that emits characteristic radiation when irradiated by the electron beam. This substrate serves as a mediator between the electron beam and the detector, enabling calibration without requiring metal glow. The characteristic radiation from the substrate provides a direct signal for beam characterization, eliminating the time-consuming heating and glowing process of traditional metal-based calibration methods.
Solution Approach 2:
The patent replaces the thermal-mechanical process of heating metal to glow with an electromagnetic detection process. Instead of relying on thermal radiation from hot metal, the system uses characteristic X-ray emission from the substrate, which can be detected immediately upon electron beam irradiation. This substitution of the calibration mechanism eliminates the time delay associated with heating metal to glowing temperature.
2Measurement precision
If optical calibration using metal glow is used, then electron beam calibration can be performed, but it requires relatively high beam power
Solution Approach 1:
The substrate acts as an intermediary that amplifies the calibration signal through characteristic radiation emission. When the electron beam irradiates the substrate, the substrate emits intense characteristic X-rays that are easily detectable even at low beam powers. This intermediary mechanism provides a strong calibration signal without requiring the high beam power needed to heat metal to glow.
Solution Approach 2:
The patent changes the calibration parameter from thermal radiation intensity (which requires high power to generate visible glow) to characteristic X-ray emission intensity (which can be detected at much lower power levels). By detecting X-rays instead of optical glow, the system achieves calibration accuracy with significantly reduced beam power requirements.
3Measurement precision
If optical calibration using metal glow is used, then electron beam calibration can be performed, but the metal may be locally damaged or changed
Solution Approach 1:
The substrate serves as a sacrificial intermediary that absorbs the electron beam energy without being part of the final workpiece. By using the substrate as the calibration target, the harmful effects of high-energy electron beam irradiation are confined to the substrate rather than the workpiece material. The substrate can be easily replaced after calibration, while the workpiece remains undamaged.
Solution Approach 2:
The patent creates a calibration copy using the substrate instead of calibrating directly on the workpiece material. The substrate provides a duplicate calibration target that replicates the necessary calibration function without being the actual workpiece. This copying approach allows calibration to be performed on a separate material that can withstand the calibration process conditions.
4Measurement precision
If optical calibration using metal glow is used, then electron beam calibration can be performed, but the optical equipment may get metallised
Solution Approach 1:
The patent extracts the calibration function from the optical path and places it in the X-ray detection path. By using characteristic X-ray emission from the substrate instead of optical glow detection, the calibration process is removed from the optical equipment's environment. This extraction prevents metal vapor or deposition from contaminating optical components, as the calibration now occurs in the X-ray detection system rather than the optical system.
5Measurement precision
If optical calibration using metal glow is used, then electron beam calibration can be performed, but there is not a straightforward relationship between glow and beam power
Solution Approach 1:
The patent replaces the complex thermal-radiation relationship (where glow intensity depends on temperature, which depends on power in a non-linear way) with a direct X-ray emission relationship. Characteristic X-ray emission intensity has a more straightforward and predictable relationship with electron beam power, simplifying the calibration process and making the relationship between beam parameters and detection signal more direct and easier to quantify.
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 method provides efficient and accurate calibration of electron beams, ensuring precise control without material alteration and enabling verification at any moment during manufacturing, improving the quality of three-dimensional article formation.
Implementation Method 1
scanning an electron beam in at least a first direction on the substrate for generating X-rays to be received by the at least one X-ray detector
Implementation Method 2
detecting the X-rays emanating from the surface produced by the scanning electron beam with the patterned aperture modulator and the patterned aperture resolver
Data Source
AI summary
A device for detecting X-rays radiated out of a substrate surface, said device comprising at least one X-ray detector, a resolver grating and a modulator grating, said resolver grating with at least one opening facing towards said X-ray detector is arranged in front of said X-ray detector. Said modulator grating is provided between said resolver grating and said substrate at a predetermined distance from said resolver grating and said substrate, where said modulator grating having a plurality of openings in at least a first direction, wherein said x-rays from said surface is spatially modulated with said modulator grating and resolver grating.