Highly improved range sensing – by reduction of spatial coherence

Optical range sensors based on triangulation are widely used for the shape measurement of optically rough objects. The origin of the achievable measuring uncertainty of the distance is speckle noise. Speckle noise is unavoidable in spatially coherent systems. We demonstrate two experiments which prove that without spatial coherence, the measuring uncertainty can be dramatically reduced, and we present an on-line 3D-sensor for laser-material processing, exploiting this knowledge.