Distance sensing to rough semitransparent and multiscattering materials using dynamic speckles

Appl Opt. 2009 Oct 1;48(28):5266-73. doi: 10.1364/AO.48.005266.

Abstract

Noncontact methods of distance measurements to a moving surface using laser light are relevant for many industrial applications, such as surface profile and position monitoring, thickness measurements, and wear estimation. Application of existing methods (e.g., triangulation) is limited especially for nonhomogeneous, semitransparent and rough materials (paper, wood, plastic). The task is even more challenging for fast moving objects. We present a novel online method of distance sensing to semitransparent and multiscattering surfaces (papers, woods, polymers) based on spatial filtering of dynamic speckles. We validated a proposed method at the speed of the test surface as high as 35 m/s.