Optical Doppler shift measurement using a rotating mirror

Optical Doppler shift demonstration experiments are not a simple task sincethe light source cannot usually be moved in a sufficiently smooth and uniformmanner to keep the level of noise well below of that of the signal. For thatreason most demonstration experiments are usually performed with sound or withmicrowaves. Previous work have been reported using a moving mirror in order toproduce a moving light source, but small perturbation of its trajectory, assmall as the optical wavelength, can produce a large noise. Using a rotatingmirror, in which one beam is reflected from the advancing side and the otherbeam is reflected from the receding part of a rotating mirror, can overcomemany of the noise generating effects. In the present work we report theconstruction and operation of a demonstration apparatus for measuring opticalDoppler shift based on a rotating mirror.Comment: 11 pages, 5 figure