激光三角法位移测量中数字散斑相关法的研究

Study on laser speckle correlation method applied in triangulation displacement measurement

在三角法位移测量中散斑是一种噪声,当成像光斑过弱而湮没于散斑中时,抑制散斑已没有意义;但散斑同样是位移信息的载体。为此针对激光三角法位移测量系统,研究数字散斑相关法;对强散射、粗糙界面的位移进行了实测,且进行了数据分析。结果表明,在激光三角法位移测量中运用数字散斑相关法对强散射、粗糙界面进行位移测量是可行的,测量范围可达微米级,测量误差小于2%。此法可改善三角法位移测量系统在强散射、粗糙界面的情形下传统测量方法的缺陷,有效提高了测量精度,并扩展了激光三角法位移测量的实用范围。

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.