Abstract

CO₂-laser anemometers as they are normally implemented will measure the velocity component along the optical axis [1] [2]. Systems based Gn visible light will normally measure the component perpendicular to the optical axis [3] [4]. Examples of measurements are given. Based on a concept introduced by Schwiesow [5] we show how the fringe and reference beam systems can be combined by using reference beam detection in a fringe type anemometer and doing the mixing electronically. An implementation is proposed.