The characterisation of the topology of single elements or of complete surfaces with high resolution is important during process development and during quality assurance. 3D measurement methods often use well-known geometric-trigonometric relations to determine coordinates. As an alternative, one can use the reflection behaviour of a measurement beam or the run-time of that beam.

The most popular sensor principles are the autofocus principle, the confocal principle and the conoscopical principle. Depending on the habit of the specimen and the measurement task, one or the other sensor principle is more useful, e.g. depending on some edge steepness, depth of holes or the reflection behaviour of the surface. The specimen surface is either scanned in multiple lines or acquired as one image at a time. Using software algorithms one can generate 3D topographic models and make different calculations based on those image data.