Bifocal Electron Microscope for Diffraction Holography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current transmission electron microscopy (TEM) systems operating in electron diffraction mode struggle to obtain the full exit wave of a specimen, as they can only record intensity values without phase information, limiting the types of objects that can be effectively imaged.
Innovation Solution
The method involves emitting a plurality of electrons toward a sample, forming them into two electron beams with different focal planes, and detecting an interference pattern in the diffraction plane to generate a diffraction hologram, which provides both phase and amplitude information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If TEM systems operate in electron diffraction mode to study crystalline materials, then crystallographic information can be obtained, but phase information is lost and only intensity values are recorded
Solution Approach 1:
The patent introduces an electron hologram as an intermediary recording medium that captures both intensity and phase information of the electron wave. By using off-axis electron holography, the system records the interference pattern between the object wave (scattered by the specimen) and a reference wave, thereby preserving phase information that would otherwise be lost in conventional diffraction mode.
Solution Approach 2:
The patent changes the detection parameter from recording only intensity values to recording the full complex wave function (amplitude and phase). This is achieved by transforming the detection mode from conventional diffraction imaging to electron holography, where the detected parameter includes both the magnitude and phase of the electron wave, enabling complete exit wave determination.
2Loss of information
If conventional diffraction methods are used, then intensity data can be collected, but the full exit wave (amplitude and phase) cannot be determined
Solution Approach 1:
The patent makes the TEM system multi-functional by integrating both conventional diffraction capability and electron holography capability into a single instrument. The system can operate in different modes (diffraction mode and holography mode) using the same electron optical column, thereby achieving full exit wave determination without requiring a completely separate holography setup.
Solution Approach 2:
The patent uses an electron biprism as an intermediary element to split the electron beam into object and reference beams, and to record their interference pattern. This biprism serves as the key component that enables holographic recording within the existing TEM architecture, bridging the gap between conventional diffraction and full wave function measurement.
3Adaptability or versatility
If phase information is obtained through off-axis holography, then full exit wave can be determined, but currently this technique can only be applied where the specimen is imaged onto the camera, not in diffraction mode
Solution Approach 1:
The patent extends electron holography from real space imaging to reciprocal space (diffraction space) by recording holograms in the diffraction plane. This dimensional transformation allows the technique to capture phase information of diffracted beams, enabling complete exit wave determination in diffraction mode and making the method applicable to a broader range of specimens including crystalline materials.
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 the determination of the full exit wave of the specimen, enabling 3D information and tomography, and overcoming the limitations of existing TEM systems by providing phase and amplitude data.
Implementation Method 1
An interference pattern of the first electron beam and the diffracted second electron beam is then detected in the diffraction plane
Data Source
AI summary
Methods for using a single electron microscope system for investigating a sample with twin electron beams having different focal lengths include the steps of emitting electrons toward the sample, forming the electrons into a two beams, and then modifying the focal properties of at least one of the two beams such that they have different focal planes. Once the two beams have different focal planes, the first electron beam is focused at the sample, and the second electron beam is focused so that it acts as a TEM beam that is parallel beam when incident on the sample. Emissions resultant from the first electron beam and the TEM beam being incident on the sample can then be detected by a single detector or detector array and used to generate a TEM image.