Publications
Doppler electron velocimeter-practical considerations for a useful tool
The Doppler electron velocimeter (DEV) is a potentially new dynamic measurement system for the nano-scale. Electron microscopes have been used for many years now for visualizing extremely small samples, but the ability to make dynamic measurements has not existed. The DEV proceeds along the analogous lines of a laser Doppler velocimeter, which uses the Doppler shift of the wave to detect the velocity. The use of electron beams with their extremely short wavelengths overcomes the diffraction limit of light of approximately 1/2-micron to measure samples of current scientific interest in the nano-regime. Previous work has shown that Doppler shifting of electrons is theoretically possible, this paper examines whether a practical instrument can be built given inherent limitations of using electron beams as a probe source. Potential issues and their solutions, including electron beam coherence and interference will be presented. If answers to these problems can be found, the invention of the Doppler electron velocimeter could yield a completely new measurement concept at atomistic scales. © 2008 Society for Experimental Mechanics Inc.