XRF Spectrometer Aperture System for Focal Depth
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Solution Overview
Problem
X-ray fluorescence spectrometers with polycapillary optics have limited focal depth, making it difficult to effectively analyze samples with complex topography, such as printed circuit boards, due to large exit aperture angles and reduced intensity.
Innovation Solution
An XRF spectrometer with an aperture system that includes a pinhole positioned between the X-ray tube and capillary lens, allowing for adjustment of the focal depth by controlling the beam cross section, thereby reducing beam divergence and increasing focal depth without compromising intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If polycapillary lenses with high entrance aperture are used to provide sufficient X-ray intensity, then the intensity is improved, but the exit aperture angles become large and the usable focal depth becomes rather low
Solution Approach 1:
The invention divides the single polycapillary lens into two separate polycapillary lenses with different functions: the first lens (L1) with high entrance aperture collects maximum X-ray intensity, while the second lens (L2) with smaller exit aperture controls the beam angle and increases focal depth. This segmentation allows each lens to be optimized for its specific function rather than requiring a single lens to satisfy conflicting requirements.
Solution Approach 2:
The second polycapillary lens (L2) acts as an intermediary between the first lens (L1) and the sample. It receives the X-ray beam from L1 and conditions it by reducing the exit aperture angle, thereby extending the focal depth without significantly reducing the intensity provided by L1. This intermediary lens mediates between the intensity requirement and the focal depth requirement.
2Manufacturing precision
If large exit aperture angles are used to focus radiation on micrometer range spots, then the focusing capability is improved, but the usable focal depth becomes rather low
Solution Approach 1:
The focusing function is segmented between two lenses: L1 provides the primary focusing with high aperture for intensity, while L2 provides secondary conditioning of the beam with smaller aperture for extended depth. This segmentation allows maintaining micrometer-scale focusing precision while extending focal depth.
Solution Approach 2:
Different parts of the optical system are given different qualities: L1 has large aperture optimized for collecting intensity and initial focusing, while L2 has smaller aperture optimized for beam conditioning and extending focal depth. Each lens is locally optimized for its specific role in the focusing chain.
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 aperture system enhances focal depth, allowing sharper imaging of samples with complex topography and reducing disturbing Bragg peaks in recorded spectra, while maintaining sufficient intensity for analysis.
Implementation Method 1
Polycapillary lenses are particularly suitable for μ-XRF and usually consist of a plurality of small hollow glass tubes that are arranged in an array and that each guide X-rays via a plurality of total external reflections.
Implementation Method 2
an aperture system that is positioned between the anode of the X-ray tube and the capillary lens, particularly between the anode of the X-ray tube and an entrance aperture of the capillary lens
Implementation Method 3
The polycapillary lens images one X-ray point source to another.
Data Source
Figure 1~2
Figure 3
Figure 4(A)~4(B)
AI summary
The present invention relates to an X-ray fluorescence, XRF, spectrometer (10), for measuring X-ray fluorescence emitted by a target (7), wherein the XRF spectrometer (10) comprises an X-ray tube (1) with an anode (2) that is emitting a divergent X-ray beam (3a), a capillary lens (6) that is configured to focus the divergent X-ray beam (3a) on the target (7), an aperture system (4) that is positioned between the anode (2) of the X-ray tube (1) and the capillary lens (6) and comprises at least one pinhole (9a, 9b), and a detector (8) that is configured for detecting X-ray fluorescence radiation emitted by the target (7), wherein the at least one pinhole (9a, 9b) is configured for being inserted into the divergent X-ray beam (3a) and for reducing a beam cross section (5a) of the divergent X-ray beam (3a) between the anode (2) and the capillary lens (6). The present invention further relates to an aperture system (4) for a spectrometer (10), to the use of an aperture system (4) for adjusting the focal depth of a spectrometer (10) and to an method for adjusting the focal depth of as spectrometer (10).