Statistical analysis of SEM image noise

Abstract

The stress-relaxation technique is one of the most popular approaches to measure macroscopic residual stresses in different kinds of materials. Recently, by using a dual beam microscope (Scanning Electron Microscope (SEM) and Focused Ion Beam (FIB) in one chamber), a new option of detection of internal stresses on a microscopic scale appeared. FIB is used to release local strain induced by internal stresses and Digital Image Correlation (DIC) of SEM images collected before and after stress release is applied to quantify strain release at the surface. However, the combination of DIC and SEM brings some new important aspects in the analysis of noise generated by the special way of building an SEM image. Because the magnitude of the strain is quite often very close to the noise level, it is very important to test each SEM column which is used in these measurements. It is necessary to study conditions for minimization and randomization of the noise generated during SEM image collection by instabilities inside electron column and sample chamber as well. In the present work, the methods for such testing will be given for a Philips XL30 ESEM. © 2013 WIT Press.