TEM diffraction spot pattern sharpening processing method

Abstract

The invention discloses a TEM diffraction spot pattern sharpening processing method which comprises the following steps: a, shooting a TEM sample, to obtain a TEM diffraction pattern; b, converting the TEM diffraction pattern into a radial intensity distribution curve by a center rotating average method; c, carrying out mirror symmetry on half a central peak formed by the TEM diffraction pattern center spots by a symmetry method, to form a complete peak; d, then fitting the complete center peak by a Gauss peak, to obtain a desired point spread function; e, processing the radial intensity distribution curve by a maximum entropy principle or a maximum likelihood method, to obtain a sharpened diffraction peak; and f, measuring the position of the sharpened diffraction peak. The method has accurate measurement results, especially can improve the measurement accuracy during measurement of lattice constants or interplanar crystal spacing by the TEM diffraction method, and has a great help on micro zone phase analysis and nano beam strain analysis.

Description

technical field [0001] The invention relates to a method for processing a TEM diffraction image, in particular to a method for sharpening a TEM diffraction spot image. Background technique [0002] In some TEM diffraction analysis methods, such as nanobeam strain analysis, the size of the diffraction spot is affected by the convergent half-angle of the electron beam. The larger the convergence half-angle, the larger the diffraction spot. Excessively large diffraction spots will inevitably affect the accuracy of the position measurement of the diffraction spots. Due to the limitations of instruments, especially low-end TEM equipment, when performing nanobeam strain analysis, the convergence half-angle cannot be adjusted to an ideal value, resulting in the obtained diffraction spots looking like diffraction disks. Such diffraction images do not allow precise lattice and interplanar spacing measurements. However, the concept of the maximum likelihood method applied to the sh...

AI Technical Summary

Problems solved by technology

Excessively large diffraction spots will inevitably affect the accuracy of the position measurement of the diffraction spots

Due to the limitations of the instrument, especially the low-end TEM equipment, the convergence half-angle cannot be adjusted to the ideal value when performing nanobeam strain analysis, resulting in the obtained diffraction spots looking like diffraction disks

Such diffraction images do not allow precise lattice and interplanar spacing measurements

However, the concept of the maximum likelihood method applied to the sharpening of the EELS spectrum cannot be directly applied to the sharpening of the TEM diffraction speckle pattern. It is necessary to convert the diffraction speckle image into a spectrum before sharpening