The temporal coherency of an electron source is described by a length called the temporal coherency length: ! = Where is the mean velocity, " , and is the energy spread of the beam. Using this equation, describe two ways you can improve the temporal coherency of your electron source for your TEM. (b) The spatial coherency of an electron source is described by a length called the effective source size: ! = 2 Where is the electron wavelength and is the angle of illumination. Using this equation, describe two ways you can improve the spatial coherency of your electron source for your TEM