Optimization of Optical Anemometers

The paper presents analyses which describe the signal obtained from fringe anemometers, Doppler-shift anemometers and combined systems: experiments carried out with nine optical geometries are described and confirm some features of the analyses. The main purposes of the paper are to clarify the significant differences between these anemometers, to aid the reader to select the optical geometry most suited to his needs and to indicate means of improving the signal:noise ratio at the photodetector.