Study on laser speckle correlation method applied in triangulation displacement measurement

The laser speckle is a kind of noise in triangulation displacement measurement. It's meaningless to restrain speckles when the light spot is so weak that facular image can not be extracted from speckles. But the speckle is also a kind of carrier of displacement information. For the above reasons, digital correlation method was used in laser triangulation displacement measurement system to measure the displacement of rough surface with strong scattering and the results had been analyzed. The results show that the digital correlation method is feasible in triangulation displacement measurement system, the measuring range reached micron grade and the experimental errors are below 2% . This method can overcome the disadvantage of laser triangular displacement measurement system in rough surface with strong scattering, improve the accuracy and expand its range of application.