FEI EMPAD: DP field of view calibration; saturation current calculation (take 2) скачать в хорошем качестве

FEI EMPAD: DP field of view calibration; saturation current calculation (take 2)

Hello EM aficionados! In this video (a retake), I cover calibration of the field of view (FOV) of the diffraction patterns (in mrad or 1/nm) of a 4D-STEM dataset collected using the EMPAD. While we always collect 4D-STEM datasets with a convergent beam, this is actually not (in my opinion) the best geometry for calibrating the FOV of the DPs. Believe it or not, the best way to do this is to use the EMPAD to collect a quick series of nominally identical parallel beam DPs from the standard AuPd replica grating. This series can then be opened in ImageJ and then averaged to produce a single high quality DP with well-defined rings, which is then easily used to calibrate the FOV of the DP for the given camera length given the known diffraction data for AuPd. Also, while the EMPAD architecture is quite robust to oversaturation, it can still potentially be damaged if the current density exceeds 2 pA/pixel. Once the FOV of the DP is known, as well as the probe semi-angle of convergence, the maximum safe current for collecting a 4D-STEM dataset with the EMPAD can be calculated using a simple equation, which I derive here. Thank you for your support, my fellow EM aficionados, as we have now surpassed 5,000 subscribers! Please like, subscribe, and share and leave any questions or comments you may have and I will do my best to reply as soon as possible. Video topic requests are always welcome and appreciated; I enjoy making these videos and wish I could make them more frequently, but the demands of my job make it tough to do so; I’m in charge of three S/TEMs, three dual FIB/SEM systems (a new one recently signed off on), and half of an SEM and this keeps me very busy! Connect with me on LinkedIn:   / nicholas-rudawski-30414528   Where I work: https://nrf.aux.eng.ufl.edu/ E-mail me directly: [email protected]