Diffractive X-ray Lens for High-Energy Microscopy
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Solution Overview
Problem
Existing X-ray microscopy devices face limitations with photon energies above 8 keV due to limited numerical aperture and increased signal noise from deceleration and kβ radiation, which reduces image quality and restricts the use of higher photon energies.
Innovation Solution
The device employs a monochromatizing and two-dimensionally focussing condenser-based optical system with a diffractive X-ray lens, such as a multilayer Laue lens or Fresnel zone plate, to achieve high monochromatic photon flux and improved imaging capabilities at higher energies, including the use of X-ray sources emitting photons greater than 5 keV, and incorporates a beam stop for hollow cone illumination to separate images from undiffracted radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If photon energy is increased above 8 keV, then penetrative capability is improved, but numerical aperture decreases due to declining critical angle of total reflection
Solution Approach 1:
The patent changes the optical configuration from total reflection-based (monocapillary) to diffraction-based (Fresnel zone plate). This parameter change in the underlying physical mechanism allows the system to operate effectively at higher photon energies where total reflection becomes inefficient, thereby maintaining both penetrative capability and numerical aperture.
Solution Approach 2:
The patent substitutes the mechanical total reflection system (monocapillary) with a diffractive optical system (Fresnel zone plate). This substitution enables the system to achieve both high penetrative capability and adequate numerical aperture at photon energies above 8 keV, resolving the contradiction between these two parameters.
2Strength
If photon energy is increased above 8 keV, then penetrative capability is improved, but bending efficiency of Fresnel zone plate decreases due to limited aspect ratio
Solution Approach 1:
The patent optimizes the geometric parameters of the Fresnel zone plate, specifically the zone width and aspect ratio, to maintain adequate bending efficiency at higher photon energies. By adjusting these parameters, the system achieves both high penetrative capability and sufficient diffraction efficiency.
Solution Approach 2:
The patent employs adjustable and optimizable parameters in the Fresnel zone plate design, allowing the aspect ratio and zone dimensions to be tuned for different photon energy ranges. This dynamic optimization maintains bending efficiency while enabling operation at higher energies for improved penetrative capability.
3Strength
If photon energy is increased above 8 keV, then penetrative capability is improved, but image quality deteriorates due to increased signal noise from deceleration radiation and kβ radiation
Solution Approach 1:
The patent uses the beam stop to extract and remove the harmful undiffracted radiation and noise components (deceleration radiation and kβ radiation) from the optical path. This separation allows the useful diffracted signal to reach the detector while blocking the noise, thereby maintaining image quality at higher photon energies.
Solution Approach 2:
The patent converts the harmful undiffracted radiation into a useful separation mechanism. By using the beam stop to block the direct beam and employing the Fresnel zone plate to diffract the useful radiation, the system transforms the noise problem into a spatial separation opportunity, where the diffracted image can be clearly distinguished from the blocked undiffracted radiation.
4Productivity
If monocapillary and Fresnel zone plate are used, then imaging is achieved, but working space between optical system and object plane is reduced
Solution Approach 1:
The patent transitions from a one-dimensional monocapillary system to a two-dimensional Fresnel zone plate system. This dimensional change allows for improved working space management and enables the use of larger samples while maintaining imaging capability. The planar structure of the Fresnel zone plate provides better spatial arrangement options compared to the tubular monocapillary.
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 efficient high-resolution X-ray imaging at higher photon energies, increasing penetrative capability and reducing signal noise, allowing for larger sample sizes and improved imaging quality in microscopy and tomography applications.
Implementation Method 1
an elliptical monocapillary which exploits total reflection is used
Implementation Method 2
A monochrornatizing and two-dimensionally focussing condenser-based optical system for focussing the emitted X-ray radiation
Implementation Method 3
provision is made for a diffractive X-ray lens for imaging the object to be imaged on the X-ray detector
Implementation Method 4
a beam stop, which is also referred to as (direct) beam attenuator, is disposed between the condenser-based optical system and the object to be imaged for masking a central beam
Data Source
AI summary
The present invention relates to an illumination and imaging device for high-resolution X-ray microscopy with high photon energy, comprising an X-ray source (1) for emitting X-ray radiation and an area detector (4) for detecting the X-ray radiation. Moreover, the device comprises a monochromatizing and two-dimensionally focussing condenser-based optical system (2) arranged in the optical path of X-ray radiation with two reflective elements (6) being arranged side-by-side for focussing impinging X-ray radiation on an object to be imaged (5) and a diffractive X-ray lens (3) for imaging the object to be imaged (5) on the X-ray detector (4). Typically, the illumination and imaging device is used for performing radiography, tomography and examination of a micro-electronic component or an iron-based material.