Charged Particle Beam Microscope Phase Retrieval Illumination
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Solution Overview
Problem
Charged particle beam microscopes face limitations in resolution due to lens aberrations and require costly aberration correction, while the phase retrieval method offers high-resolution imaging without lenses but is time-consuming and requires multiple procedures.
Innovation Solution
The implementation of an illumination adjustment system and a deflector in charged particle beam equipment to ensure the illumination area on the specimen corresponds to the image size of the reconstructed object image, aligning the diffraction pattern with the object image, and using a magnified image for phase retrieval to enhance calculation convergence and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If aberration correction technique is used to reduce lens aberration, then resolution is improved, but equipment cost increases
Solution Approach 1:
The patent extracts the lens component from the imaging system and replaces it with a lensless diffraction pattern acquisition approach. By removing the lens that causes aberrations, the system achieves high resolution without requiring expensive aberration correction equipment, directly resolving the contradiction between resolution improvement and equipment cost increase
Solution Approach 2:
The patent replaces the mechanical/optical lens-based imaging system with a computational imaging approach using phase retrieval algorithms. This substitution eliminates the need for physical aberration correction mechanisms while achieving superior resolution through mathematical reconstruction of the object image from diffraction patterns
2Measurement precision
If phase retrieval method is used to reconstruct object image from diffraction pattern, then resolution is improved without lens aberrations, but processing time increases
Solution Approach 1:
The patent applies preliminary action by using a magnified image obtained from the same diffraction pattern as an initial condition for the phase retrieval calculation. This preliminary image provides a head start for the iterative reconstruction process, significantly reducing the number of iterations needed and thus decreasing processing time while maintaining high resolution
Solution Approach 2:
The patent implements feedback by using the magnified image derived from the diffraction pattern to guide and constrain the phase retrieval process. This feedback mechanism accelerates convergence by providing realistic initial amplitude information, reducing processing time without sacrificing the high resolution advantage of lensless imaging
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 approach allows for high-resolution imaging without lens aberrations, reducing the time required for object image reconstruction and improving accuracy by maintaining the proportionality of the diffraction pattern to the object image, thus overcoming the limitations of traditional microscopes.
Implementation Method 1
A diffraction pattern can be obtained without using a lens, so that, in the phase retrieval method, it can be expected to observe an image with a high resolution and without the influence of the aberrations of the lens
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
In an electron microscope to which a phase retrieval method is applied, an image size determined by a pixel size p of a diffraction pattern, a camera length L, and a wavelength λ of an illumination beam is allowed to have a certain relation with an illumination area on a specimen. Further, a beam illumination area or a scanning area of a deflector when a magnified image is observed is set by an illumination adjustment system, so that an image size when the magnified image is used for the phase retrieval method is allowed to have a certain relation with the image size determined by the pixel size of the diffraction pattern, the camera length, and the wavelength of the illumination beam. Accordingly, the information of the diffraction pattern is substantially equal to an object image to be reconstructed.