Improving chemical mapping algorithm and visualization in full-field hard x-ray spectroscopic imaging

Cheng Chang, Wei Xu, Yu Chen Karen Chen-Wiegart, Jun Wang, Dantong Yu

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

X-ray Absorption Near Edge Structure (XANES) imaging, an advanced absorption spectroscopy technique, at the Transmission X-ray Microscopy (TXM) Beamline X8C of NSLS enables high-resolution chemical mapping (a.k.a. chemical composition identification or chemical spectra fitting). Two-Dimensional (2D) chemical mapping has been successfully applied to study many functional materials to decide the percentages of chemical components at each pixel position of the material images. In chemical mapping, the attenuation coefficient spectrum of the material (sample) can be fitted with the weighted sum of standard spectra of individual chemical compositions, where the weights are the percentages to be calculated. In this paper, we first implemented and compared two fitting approaches: (i) a brute force enumeration method, and (ii) a constrained least square minimization algorithm proposed by us. Next, as 2D spectra fitting can be conducted pixel by pixel, so theoretically, both methods can be implemented in parallel. In order to demonstrate the feasibility of parallel computing in the chemical mapping problem and investigate how much efficiency improvement can be achieved, we used the second approach as an example and implemented a parallel version for a multi-core computer cluster. Finally we used a novel way to visualize the calculated chemical compositions, by which domain scientists could grasp the percentage difference easily without looking into the real data.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE-IS and T Electronic Imaging - Visualization and Data Analysis 2014
DOIs
StatePublished - Mar 3 2014
Externally publishedYes
Event21st annual IS and T/SPIE Conference on Visualization and Analysis, VDA 2014 - San Francisco, CA, United States
Duration: Feb 3 2014Feb 5 2014

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume9017
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Other

Other21st annual IS and T/SPIE Conference on Visualization and Analysis, VDA 2014
Country/TerritoryUnited States
CitySan Francisco, CA
Period2/3/142/5/14

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

Keywords

  • Chemical mapping
  • Parallel computing
  • Spectra fitting
  • Spectroscopy
  • Visualization
  • XANES

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