Experimental demonstration of high spatial coherence of laser-triggered field emitters

We demonstrate high spatial coherence of a laser-triggered electron source based on a sharp tungsten tip. An upper bound for the effective source radius of 1.6 nm in laser triggered electron emission is inferred from analysis of electron interference patterns of an electrostatic biprism interferometer based on freestanding carbon nanotubes in a laser-triggered point projection microscopy setup. It demonstrates that laser-triggered nanotip emitters are almost as coherent electron emitters as cold field emission sources. This observation will enable time-resolved high-resolution electron microscopy and diffraction.