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| Hauptseite > Online First > No more shots in the dark - Highly efficient compression basis for live ptychography |
| Hauptseite > Online First > No more shots in the dark - Highly efficient compression basis for live ptychography |
| Poster (After Call) | FZJ-2025-05531 |
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2025
Abstract: The field of electron microscopy (EM) will soon be a hundred years old.However, advances in aberration correction have improved transmission EM during the last two decades.Single atoms can now become visible.We can move the electron beam focus over a sample to get scanning transmission electron microscopy (STEM) data.Then, a 2D-array of scan points come in sequentially, while each scan point is a 2D diffraction image, hence are called 4D-STEM data sets.The Wigner distribution deconvolution method (WDD) allows to visualize a real-space representation of the sample.However, WDD with full images is costly and has so far been performed as a postprocessing step only.A viable alternative is data compression on the diffraction images.Various methods of dimensionality reduction have been tried.Our approach is to use the circular harmonic oscillator (CHO) basis for three reasons:(1) The CHO basis has been found to be highly efficient in compressing typical 2D diffraction images while suppressing statistical noise.(2) The factorizable property of the Cartesian representation of a CHO basis allows for CHO basis transformations using a two-step scheme of efficient matrix-matrix multiplications with SGEMM.(3) The WDD procedure can skip two Fourier transforms due to an analytical property of the CHO basis.Combining the three aspects of acceleration LiberTEM-live can visualize 4D-STEM data using CHO-WDD in milliseconds on a GPU, even on incomplete scans.This allows EM operators to finally see what they measure while the scan is still running.
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