Non-contact surface analysis by use of monochromatic speckle techniques

For technical production processes it is often required to realize a parametric roughness measurement method with non-contact function and high operation speed that can be implemented as in-process quality control. Monochromatic speckle techniques are alternatives to the well-established light scattering methods (TIS, ARS). We present the technical application of these principles by examples of practical sensor developments. The methods are based on the statistical evaluation of modulated intensity pattern that are reflected or transmitted by the probe surface. Depending on the typical roughness region speckle fields will be evaluatied either separately or by their comparison with variation of one of the illuminace parameters. A special application is the roughness analysis of vertical surface structures that can not be examined by conventionall techniques like stylus or optical profilometers. We mention the possibility of numerical simulation of any speckle measurement setups.