The Principle of Wavefront Reconstruction, 1948
24 years ago, in 1947, I was very interested in improving the electron microscope. The electrons used in microscopy have wavelengths of the order of 0.05 Angstroms, hence one might have thought that they not only allow us to see atoms, but even explore their details. This of course is a naive view; there are some very fundamental reasons which will forever prevent us to explore the inside of individual atoms. But at least, one would think, it ought to be possible to resolve atomic lattices, which have usually atom spacings of the order of 2 – 3 Angstroms. Unfortunately, it turned out that electron lenses, electric or magnetic, cannot be made perfect, they have a spherical aberration which at best would allow us to go down to 3 – 4 Angstroms. This was the theoretical limit in 1947, now it is practically reached, while in 1947 the practical limit was about 12 Å.
KeywordsReference Beam Spherical Wave Spherical Aberration Holographic Interferometry Object Beam
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