Laser-Doppler sensor system for speed and length measurements at moving surfaces

Laser-Doppler Velocimetry is a contact less method for measuring the speed and the path length of moving solid-state surfaces or of fluid stream. In the past the main application of this method was fluid mechanics, No other method was as suitable as Laser-Doppler Anemometry to measure the speed of stream at arbitrary positions, Therefore the market accepted the very high price of these systems. In the past for the measurement of solid-state surfaces mostly other methods with a more reasonable price were used. However from a pure technical point of view a contact less and precise method as Laser-Doppler Velocimetry is also very attractive for the measurement of solid-state surfaces, The method is suitable for nearly any type of technical surface. The measurement procedure does not damage the surfaces and no slippage occurs. These advantages will be become important also for standard applications, if the price of the LDV systems can compete with the price of other methods. Micro systems technology allows not only the fabrication of miniaturized systems, but also for a competitive price.