Study on laser speckle correlation method applied in triangulation displacement measurement

Laser speckle is a kind of noise in triangulation displacement measurement. It's meaningless to restrain speckles when the imaging light spot is so weak that facular image cannot be extracted from speckles. Speckles can also be viewed as a kind of information carrier of displacement of the interface. In this paper, digital correlation method was used in laser triangulation displacement measurement system to measure the displacement of rough surface with strong scattering and the experimental results were analyzed. The results show that the digital correlation method is feasible in triangulation displacement measurement system, the measuring range can reach micron grade and the experimental errors are below 2%. This method can overcome the disadvantage of traditional laser triangular displacement measurement in rough surface with strong scattering, improve the accuracy and expand the scope of application. (C) 2013 Optical Society of America.