Pulsed Sources. (a) Anode current and X-ray intensity temporal response plots showing an X-ray beam turn-on time of <50 μs, and X-ray images of a rotating computer cooling fan acquired at a constant fan angular velocity with decreasing X-ray emission pulse width. Note the increased sharpness of the fan blades with increasingly rapid beam pulsing . Copyright 2005, Joint Committee on Powder Diffraction Standards. (b) Bias voltage and X-ray emission temporal response plots with an acquired X-ray image of a users hand [149,156]. Copyright 2003, Elsevier and American Institute of Physics. (c) The time dependence of the cathode voltage with integrated pull-up resistance showing a rise time of <3 μs . Copyright 2013, SPIE. (d) Schematic depiction of a red-source photo-gated CNF-based electron source. Each vertically aligned CNF bundle sits on top of a pin+ photodiode coated with a TiN diffusion barrier coated and a Ni catalyst, as illustrated in the scanning electron micrograph taken after the CNT growth (Scale bar: 1 μm). Adapted from . Copyright 2014, Thales Electron Devices.