Multilayer Mirror X-ray Topography Apparatus
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Solution Overview
Problem
Conventional X-ray topography apparatuses face limitations in increasing the irradiation region of a desired characteristic X-ray while maintaining high image quality, leading to reduced brightness and longer measurement times, especially when using curved monochromator crystals which restrict the angle of divergence and require geometric slits, limiting their application to specific methods like the Lang or Berg-Barrett methods.
Innovation Solution
An X-ray topography apparatus utilizing a multilayer mirror with a graded multilayer spacing and a curved reflective surface, allowing for monochromatization and collimation of X-rays without geometric slits, enabling a wider irradiation region and improved brightness by reflecting the X-rays as a fan beam, which can be adjusted for transmission or reflection geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a geometric slit is used to restrict the angle of divergence of X-rays, then the X-ray can be regarded as substantially collimated, but the irradiation region is limited and brightness is decreased
Solution Approach 1:
The patent replaces the geometric slit (mechanical component) with a multilayer mirror (optical component) to achieve X-ray collimation. The multilayer mirror uses Bragg diffraction to selectively reflect desired characteristic X-rays while absorbing others, eliminating the need for geometric slits and enabling wider irradiation regions without sacrificing collimation quality
Solution Approach 2:
The patent changes the approach from geometric restriction (slit width) to optical selection (multilayer mirror spacing). By adjusting the multilayer spacing to match the desired characteristic X-ray wavelength, the system achieves selective reflection and collimation without the irradiation region limitations imposed by geometric slits
2Measurement precision
If a geometric slit is used to separate desired characteristic X-ray from another characteristic X-ray, then the unwanted diffraction image is prevented, but the irradiation region is limited
Solution Approach 1:
The patent replaces the geometric slit with a multilayer mirror that uses Bragg diffraction for X-ray separation. The multilayer mirror's periodic structure selectively reflects the desired characteristic X-ray wavelength while absorbing other wavelengths, achieving spectral separation without the irradiation region constraints of geometric slits
Solution Approach 2:
The patent transitions from spatial separation (geometric slit position) to spectral separation (multilayer spacing). By designing the multilayer spacing to correspond to the desired characteristic X-ray wavelength, the system achieves wavelength-selective reflection, separating characteristic X-rays without limiting the irradiation region
3Measurement precision
If a curved monochromator crystal is used to monochromatize X-ray, then the desired characteristic X-ray is separated from another X-ray, but the angle of divergence is restricted and measurement time is increased
Solution Approach 1:
The patent replaces the curved monochromator crystal with a flat multilayer mirror structure. The multilayer mirror achieves monochromatization through Bragg diffraction from its periodic layered structure, eliminating the need for curved geometry and reducing the measurement time associated with curved crystal monochromatization
Solution Approach 2:
The patent changes from curved crystal geometry to flat multilayer geometry. The multilayer mirror achieves the same monochromatization function through controlled layer spacing rather than curved surface geometry, enabling faster measurement times while maintaining spectral separation of characteristic X-rays
4Measurement precision
If the slit width is reduced to restrict the angle of divergence, then the X-ray becomes substantially collimated, but the brightness of the incident X-ray is decreased
Solution Approach 1:
The patent replaces the geometric slit with a multilayer mirror that achieves collimation through Bragg diffraction. This optical approach allows maintaining wider beam widths (higher brightness) while achieving the required collimation for topography measurements, as the multilayer mirror selectively reflects X-rays at specific angles without the brightness loss inherent in narrow slits
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 enhances the irradiation region and image quality by selectively reflecting the desired characteristic X-ray, reducing background noise and measurement time, while offering greater design flexibility by eliminating the need for geometric slits and allowing application across various X-ray topography methods.
Implementation Method 1
The multilayer mirror includes a curved reflective surface having a parabolic cross section... a part of the X-ray generated from the X-ray source enters the curved monochromator crystal, and is converged and focused by the curved monochromator crystal
Implementation Method 2
The multilayer mirror includes a curved reflective surface having a parabolic cross section, and the fine focal point of the X-ray source is provided onto a focal point of the curved reflective surface
Data Source
AI summary
Provided is an X-ray topography apparatus capable of separating a desired characteristic X-ray which enters a sample from an X-ray which is radiated from an X-ray source, and increasing an irradiation region of the desired characteristic X-ray. The X-ray topography apparatus includes: the X-ray source for radiating the X-ray from a fine focal point, the X-ray containing a predetermined characteristic X-ray; an optical system including a multilayer mirror with a graded multilayer spacing which corresponds to the predetermined characteristic X-ray, the optical system being configured to cause the X-ray reflected on the multilayer mirror to enter the sample; and an X-ray detector for detecting a diffracted X-ray. The multilayer mirror includes a curved reflective surface having a parabolic cross section, and the fine focal point of the X-ray source is provided onto a focal point of the curved reflective surface.