A Doppler Difference Method for Velocity Measurements
Helmut Stein, H. J. Pfeifer · Metrologia · 1969
It is the purpose of this paper to describe a Doppler difference method whereby the object to be measured is irradiated simultaneously with two partial rays being coherent relative to one another. Thus, for a given object velocity and a given wavelength of the electromagnetic radiation, the Doppler beat frequency may be varied to a great extent.