Compound X-Ray Lens Alignment via Microbead Spacers
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Solution Overview
Problem
Fabricating high-resolution and high-efficiency x-ray zone plate lenses with extreme thickness-to-width aspect ratios is challenging due to difficulties in fabrication and mechanical stabilization, especially at higher x-ray energies, where thicker zone plates are required to maintain efficiency, but their narrow outer zones are prone to mechanical stress and charging effects.
Innovation Solution
The development of compound x-ray lenses by aligning and bonding multiple zone plate frames with microbeads and adhesives to achieve precise alignment and increased focusing efficiency, allowing for the construction of thicker zone plates with high aspect ratios while ensuring mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If zone plate thickness is increased to maintain efficiency at higher x-ray energies, then focusing efficiency is improved, but mechanical stability deteriorates due to high aspect ratios
Solution Approach 1:
The patent divides a single thick zone plate into multiple thinner zone plate segments stacked along the optical axis. Each segment has a manageable thickness that maintains mechanical stability, while the collective stack achieves the required total thickness for high focusing efficiency at multi-keV x-ray energies. This segmentation resolves the contradiction by allowing the system to benefit from both thin individual elements and effective cumulative thickness.
2Measurement precision
If outer zone width is decreased to achieve higher resolution, then resolution is improved, but manufacturing precision becomes more difficult due to extreme aspect ratios
Solution Approach 1:
The patent segments the zone plate structure into multiple frames, each containing a portion of the zone pattern. This allows the outer zones to be fabricated with relaxed tolerances in each individual frame, avoiding the extreme aspect ratio challenges of a single monolithic structure. The segmented approach maintains high resolution while significantly improving manufacturability.
Solution Approach 2:
The patent transitions from fabricating a single thick zone plate in one dimension to stacking multiple thinner frames along the optical axis (adding a longitudinal dimension). This dimensional change allows the outer zones to be made with practical aspect ratios in each frame, while the stacked configuration achieves the required resolution and focusing properties.
3Loss of energy
If multiple zone plates are aligned and bonded to form compound lens, then focusing efficiency is enhanced, but device complexity increases
Solution Approach 1:
The patent segments the compound lens into multiple discrete zone plate frames that can be independently fabricated and then assembled. This segmentation enables modular manufacturing and simplifies the alignment and bonding process compared to creating a single complex thick zone plate, as each frame can be prepared separately using standard fabrication techniques.
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 compound zone plate design maintains high resolution and significantly enhances focusing efficiency, overcoming the challenges of fabricating and stabilizing thick zone plates, enabling effective imaging at higher x-ray energies.
Implementation Method 1
nearly all such x-ray microscopes use diffractive objective lenses, called Fresnel zone plates. As illustrated in FIG. 1, they are essentially circular diffraction gratings, with the grating spacing decreasing with increasing distance from the center in order to increase the diffraction angle and thus produce the focusing effect.
Implementation Method 2
The compound zone plate design maintains high resolution and significantly enhances focusing efficiency, overcoming the challenges of fabricating and stabilizing thick zone plates, enabling effective imaging at higher x-ray energies.
Data Source
AI summary
A compound zone plate comprising a first zone plate frame including a first zone plate, a second zone plate frame including a second zone plate, and a base frame to which the first zone plate frame and the second zone plate frame are bonded. In examples, two more zone plates are added to make a four element optic. In the assembly process, the microbeads are used to ensure the parallelism, dial in the distance precisely between the zone plates by selecting the microbead size, possibly in response to the width of the frames, and ensure low friction lateral movement enabling nanometer precision alignment of the zone plates with respect to each other prior to being fixed by the adhesive. That is, when the frames are pressed together to ensure parallelism, it is still possible to align them to each other since the microbead layer facilitates the inplane movement of the alignment process.