RAPID-JS, a cross-platform application for instant indexing SAED patterns of cubic materials via a web-browser

Zenodo (CERN European Organization for Nuclear Research)

Abstract

ABSTRACT RAPID-JS is a browser-based implementation of the Rn-ratio method for indexing selected area electron diffraction patterns of cubic and pseudocubic materials. Implemented in Svelte/ECMAScript (JavaScript) and accelerated by precomputed lookup tables covering 136 common orientations of P, I, F, and diamond lattices, RAPID-JS allows the interactive indexing of calibrated and uncalibrated selected area electron diffraction spot patterns via a graphical user interface. The program supports the standard image formats JPG and PNG for pattern import, and returns lattice orientations and diffraction spot indices within user-defined tolerances for ratios and angles. RAPID-JS is a lightweight, cross-platform tool designed to facilitate the quick on-site analysis of selected area electron diffraction patterns in electron microscopy and crystallography research and teaching courses. Changes: The diffraction spot positions A, B and C, corresponding to the hkl Laue indices in the results section, are indicated by small orange circles. Tutorial: Weirich, T.E. (2026). Computer-Assisted Determination of Orientation Relationships from Selected-Area Electron Diffraction: A Beginner's Guide to Pattern Indexing with RAPID-JS, Technical Report No. 1-2026, Central Facility for Electron Microscopy (GFE), RWTH Aachen University. https://doi.org/10.18154/RWTH-2026-07859Note on the received UVWs: RAPID-JS only provides the standard orientations listed in the Atlas of Zone Axis Spot Patterns for Cubic Lattices as solution. If an alternate orientation is needed, use the tables provided in the supporting material of https://doi.org/10.1107/S1600576726003031 for easy reindexing. Cite this software as:Weirich, J., Weirich, T.E. (2026). RAPID-JS: A Cross-platform Application for Instant Indexing SAED Patterns of Cubic Materials via a Web Browser. Microscopy Today 34(2), 15–20. https://doi.org/10.1093/mictod/qaag019

Authors 2

1. Jakob Weirich
2. Thomas E. Weirich Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University