研究目的
Investigating the rotation properties of vortex beams during propagation using electron holography.
研究成果
The study successfully developed a combined technology of electron holography and vortex beam technique, confirming that electron vortex beams propagate while twisting in space. The method allows for the separate reconstruction of amplitude and phase distributions of propagating electron vortex beams.
研究不足
The study focuses on a very low spatial frequency region for small angle electron diffraction patterns, where spherical aberration effects are negligibly small. The technique requires precise control of the defocusing factor for accurate reconstruction of amplitude and phase distributions.
1：Experimental Design and Method Selection:
The study combined vortex beam technique with electron holography to investigate the rotation properties of vortex beams. A fork-shaped grating was irradiated with a convergent incident electron wave to generate vortex beams and a transmitted wave as a reference wave.
2：Sample Selection and Data Sources:
A fork-shaped grating made of Si3N4 membrane was used to generate vortex beams. The grating's intensity transmittance was about 44%.
3：4%. List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: A 300-kV field emission TEM (HF-3300S) was used to observe the generated vortex beams. A focused ion beam instrument (NB-5000) was used to fabricate the grating.
4：Experimental Procedures and Operational Workflow:
The grating was irradiated with a wide area of 50 μm in diameter, 10 times the opening diameter of the grating. Two-wave interference patterns were recorded as holograms.
5：Data Analysis Methods:
Reconstruction of amplitude and phase distributions was performed using the Fourier transform method. The wave aberration function was used to compensate for defocusing factors.
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