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Our custom-developed DE-FreeScan scan generator was originally developed in collaboration with academic laboratories researching compressive sensing applications for scanning transmission electron microscopy (STEM). To pursue this research, investigators required the ability to arbitrarily change the scan patterns so that various subsampling strategies could be evaluated. As a result of this collaboration, Direct Electron developed the DE-FreeScan scan generator.
In addition to subsampling and compressive sensing, the flexibility of the DE-FreeScan enables users to apply non-standard scan patterns to accomplish other goals such as minimizing specimen damage or developing time-efficient scan patterns based on features of interest. While the DE-FreeScan works well with conventional analog STEM detectors to enable customizable STEM scan patterns, it is most powerful when paired with Direct Electron’s direct detection camera systems.
DE-FreeScan is the optimal accessory for enabling 4D STEM using Direct Electron’s cameras. 4D STEM is the acquisition of diffraction images instead of single integrated values in STEM. This enables simultaneous acquisition of a range of dark-field angles and the coherent bright-field (BF) diffraction pattern at every probe position. By detecting the scattering angle of nearly all the primary electrons that interact with the specimen, this technique promises to provide much more information about the specimen than conventional STEM using only conventional integrating detectors. 4D STEM enables a wide range of analysis techniques, including ptychography (for phase contrast), orientation mapping, magnetic-field mapping, and elemental discrimination. For a more in-depth guide to 4D STEM, see our article in Microscopy and Analysis magazine, written in collaboration with Prof. Paul Voyles at the University of Wisconsin Madison.
In addition to supporting 4D STEM, the DE-Freescan can be used as an accessory for low-kV electron microscopy. For example the DE-Freescan has been used on an SEM with our DE-SEMCam camera to perform electron backscattered diffraction mapping (see publication).
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