By Akira Tonomura
Electron holography, a two-step imaging technique making the most of gentle and electrons, has been hired for primary experiments in physics in addition to for high-precision measurements in microscopy. It is still complex in its functions although the rate of the advance isn't really excessive yet regular including technical advancements of either the coherent electron beam and the reconstruction method. development has been made because the ebook of the 1st version of this publication in 1993, and this moment edi tion with new effects built-in is herewith made to be had. i'm hoping that the current monograph may also help improve this fascinating box of electron interference extra. Hatoyama Akira Tonomura December 1998 v Preface to the 1st version Electron holography has lately paved a brand new means for looking at and meas uring microscopic items and fields that have been formerly inaccessible em ploying different options. complete use is made up of the tremendous brief wave size of electrons, permitting electron holography to have a superb effect on fields starting from uncomplicated technological know-how to business purposes. This e-book will supply an summary of the current country of electron holography for scien tists and engineers getting into the sector. the rules, innovations and appli cations that have already been constructed, in addition to these that are ex pected to come up within the close to destiny, can be discussed.
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Additional info for Electron Holography
22]; (ii) using a concave optical lens to apply a negative aberration to the image; and (iii) using the aberration inherent in the imaging method of holography to correct the image. Tonomura et al. 21] used method (ii), which was theoretically proposed by Weingartner et al. 23]. In their actual experiment, however, a conjugate image, which has a negative spherical aberration, was restored onto an aberration-free image by using a convex lens instead of a concave lens, simply because the optical reconstruction system becomes simpler when a convex lens is used.
Since the electric AB effect is technically too difficult to demonstrate it experimentally, one usually means with the AB effect the magnetic type. An experimental configuration for demonstrating the magnetic AB effect is depicted in Fig. 1. When an electric current is applied to an infinitely long solenoid, a magnetic field is produced only within the solenoid, and two electron waves starting from a single point pass around the solenoid. Even though the two waves never touch the magnetic field, a phase difference proportional to the enclosed magnetic flux is produced between them.
Classical electrodynamics does not consider that electrons outside the solenoid would "know" about the magnetic flux inside. 1) El/; , where m, -e, Ii, l/;, A, V are the electron mass, the electron charge, Planck's constant divided by 271", the wave function, the vector potential, and the scalar potential, respectively. If we assume that electromagnetic fields are weak enough to influence an incident electron wave only slightly, we can solve this equation using the WKB approximation: When the wave function l/; is expressed by both the amplitude R and the phase Sf Ii as follows: l/; Re iS11i , lr--- - - - A: Vector potential (B=rot A) Electron source Screen Solenoid difference Interference pattern Fig.
Electron Holography by Akira Tonomura