Dr. Patrick Camus, Director of Engineering, EDAX
EBSD sensors have changed as camera technologies have evolved. They began as intensified video cameras, then improved to scientific grade CCD cameras. These have provided both the high pixel count and high speed needed for EBSD acquisition requirements. Typical sensor sizes exceed 1M pixels at 10 fps for pattern quality applications and high-binning sensors are used for 1,500+ fps mapping applications at beam currents <=10 nA.
Newer technologies are appearing from imaging research labs that have similar pixel resolutions but significantly higher fps values. Unfortunately, the 1st generation of these devices do not have quite the sensitivity of the older devices, but each journal publication shows improvements.
- R N Clough, et al, “Direct Detectors for Electron Microscopy”, 2014 J. Phys.: Conf. Ser. 522 012046
- R. Clough, et al, “Direct Digital Electron Detectors” in Advances in Imaging and Electron Physics, Volume 198 # 2016 Elsevier Inc. ISSN 1076-5670
- Angus J. Wilkinson, et al, “Direct Detection of Electron Backscatter Diffraction Patterns”, PRL 111, 065506 (2013)
- S. Vespucci, et al, “Direct electron imaging of EBSD patterns using a CMOS hybrid pixel detector”, RMS-EBSD Workshop 2013
- K.P. Mingard, et al, “Practical Application of Direct Electron Detectors to EBSD Mapping in 2D and 3D”, Ultramicroscopy (2017)
- Angus Kirkland, “A Detector Revolution: Direct Silicon Detectors for Electron Microscopy”, EMAS 2017
Recent devices under test are providing binned patterns at 3,000 indexed fps, which provide 99% indexing quality but require a higher beam current of 40 nA. When performing higher resolution imaging at low beam energies (<=5 keV), less than 1 nA is required, which is significantly lower than previous devices, for full camera resolution at 100 fps.
Many interesting developments are occurring with EBSD sensors. My colleagues will be reporting on those findings in the coming months.