The Study Of Laser Doppler Velocimeter (LDV) For Solid Surface

Laser Doppler velocipedes (LDV) is a no-contact technique for speed measurement of moving solid-state surfaces, which is applied extensively in analysis of the motion of a solid body both in the scientific research and in the industrial experimentation fields with no damage to the surface and no slippage and high accuracy. The applicability and accuracy of the technique depend on the conditions in which the system operates: the characteristics of the surface measured, photoelectric detector, the environmental conditions, spectrum broadened, signal processing, etc. Our country import completely LDV for solid in high price" because of without native product and technology. Now, no theories can explain perfectly the reason of Doppler signal generating in LDV for solid, so developing the LDV for solid is very important and have a big potential market.In this paper, the history, status quo and trend of LDV is firstly introduced and the principle, method, optical design and signal processing of LDV is secondly summarized. Then based on a theoretic model of fringes and the principle of light interfering and scattering, a mathematic model of LDV for solid-state surfaces has been developed for analyzing the reason of Doppler signal forming and we analyze the relationship between the characteristics of the solid-state surface and the measurement accuracy for velocity through computer simulation in details, the results of experiment accord with the results of simulation exactly. The analysis leads to the conclusion that LDV system can measure precisely the speed of moving solid-state surface, which surface roughness within the range depending on the measuring volume and fringe spacing .The study is useful for the designing and application of LDV.At last, based on the result of numerical simulation and the theory of LDV, we design a LDV for solid in laboratory and measure accurately the velocity of solid surface in success. The system has the characters of real-time and precise because of using the digital signal processor (DSP), so it is suitable for industry application exactly. The study of LDV for solid surface offers the theory and experimental information for developing the commercial product.