Elimination of the Background of Electron Microscope Images by Using FPGA

Abstract

The purpose of our development is to design an FPGA based hardware acceleration system that is able to be used for analyzing photoemission electron microscope (PEEM) images or improving their quality. Even though a usual PEEM has an energy filter unit, which is able to eliminate certain disturbing signals, a post processing computation can also be useful to improve the image quality. Here we propose an FPGA based hardware acceleration system for the computation of a certain image background component. It has uniquely designed hardware modules that perform the computations in parallel, resulting in less calculation time. The system shown here is a prototype which was only used for testing and experimental purposes.

Filtering Chromatic Aberration for Wide Acceptance Angle Electrostatic Lenses II—Experimental Evaluation and Software-Based Imaging Energy Analyzer

“…However, the effect of chromatic aberration in first order is proportional to the electron energy that on the one hand makes possible the measurement of spectral images at different pass energies, but on the other hand it also has disadvantages especially by mixing the 3D angular-, spatial and spectral information (Figs. 1,3) [9,11,12,14,17,18]. It occurs by the phenomenon that the higher and lower kinetic energy electrons emitted from different points can also hit on the same pixels of the images of desired specific pass energy Therefore, in the case of WAAEL based lenses the elimination of the distortion effect of the chromatic aberration is unavoidable to take the advantages that these types of electrostatic lenses provide.…”

“…In this case the real-or kspace diffraction image is moved and therefore scanned in front of the entrance slit by the help of electrostatic or magnetic deflectors, while behind the exit slit of the CHA the selected energy spectral line, that is the monochromatic image of the entrance slit, is recorded and used to reconstruct the monochromatic image, slice by slice, parallel to the motion of the original image at the entrance slit [14,15]. We started to improve the quality of image data from the image processing side, in background fitting and subtraction for the integrated image intensities [14] and then the dot by dot Shirley-type background of the images were subtracted from the same coordinated pixels along the energy axes' of the spectral image sequences [17]. In this and the following cases all of the image points were taken into account as being very small entrance slits of independent spectrometers.…”