A novel laser triangulation technique for high precision distance measurement

The authors describe an optical triangulation technique for noncontact distance measurement which yields high accuracy with a large depth of field and stand-off from the target. The theoretical error of this gauging technique is 0.5 μm over a depth of field of 2 mm at distance of 100 mm from an optically rough target. The only limitation placed on the target surface is that it must diffuse a small amount of light. The gauge is also robust in the presence of vibration. An experimental gauge has been constructed using commercially available optical components, and its performance is described