A novel mathematic model of LASER Doppler velocimeter for the velocity measurement of solid-state surface

The interference fringe model and the principle of light scattering are applied to establish a mathematic model of LASER Doppler velocimeter (LDV) to analyze the Doppler signal of the solid-state surface. The reflectance and the average size of particles are used to represent the characteristic of the solid-state surface. The relationship among the characteristics of the solid-state surface, the signal intensity and the measurement accuracy is given by numerical simulations and experiments. Results show that Doppler signal is a cosine signal superposed on a Gaussian basement; the relative error of the system is less than 0.5% when the average size of particles is smaller than 140 μm, but the relative error fluctuates strongly and the measurement is not accurate when the average size of particles is larger than 140 μm. LDV will measure the speed of a moving solid-state surface precisely if the surface roughness is within the range.