Segmental Ronchigram Autocorrelation Function
Matrix (SRAM) for Aberration Correction
- Practical Electron Microscopy and Database -
- An Online Book -  

This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.


Sawada et al. [1] had used segmental Ronchigram autocorrelation function matrix (SRAM) method to measure the aberration coefficients before and after aberration corrections. Figure 2743a shows the central parts of the Ronchigram patterns in a focal series. The Ronchigrams from the amorphous film were divided into 7 × 7 segments in order to calculate the aberration coefficients (up to fifth-order) and to perform autocorrelation functions. The absolute values of each aberration coefficient were calibrated by referring to the difference between the defocus values of the two Ronchigrams [2]. Furthermore, the residual aberration can also be obtained by comparing the experimental and calculated simulations of Ronchigrams.

focal series of Ronchigrams and Autocorrelation functions

Figure 2743a. The focal series of Ronchigrams: (a) Under-focus of 128 nm and (b) Over-focus of 128 nm. (c) and (d) Grided images of (a) and (b), respectively. (e) and (f) Autocorrelation functions from (a) and (b), respectively. Adapted from [1]




[1] Sawada H, Sannomiya T, Hosokawa F, Nakamichi T, Kaneyama T, Tomita T, Kondo Y, Tanaka T, Oshima Y, Tanishiro Y, and Takayanagi K (2008) Measurement method of aberration from Ronchigram by autocorrelation function. Ultramicroscopy 108: 1467–1475.
[2] J. A. Lin, J.M. Cowley, Ultramicroscopy 19 (1986) 31.



The book author (Yougui Liao) welcomes your comments, suggestions, and corrections, please click here for submission. If you let book author know once you have cited this book, the brief information of your publication will appear on the “Times Cited” page.