Calibration strategies for a new fast line-based form measuring system

Common approaches to measure the form of precision components comprise single point as well as optical matrix sensors. Single point sensors are slow, because the sensor has to be guided point-by-point with respect to the specimen. Optical full aperture matrix sensors measure the specimen at once but are limited in their height measurement ranges. We are developing - within a Deutsche Forschungsgemeinschaft project - a new form measurement system which uses a fast interferometric line sensor in combination with a five-axes movement system, which allows fast measurements of arbitrary rotational symmetric specimens. With additional measurements of the relative position of the sensor and the specimen as well as redundant information due to the overlap of the line-shaped sub-apertures, the error of the movement axis can be corrected. As the sensor is tilted by the five-axes movement system for the purpose of having the optical axis of the sensor is perpendicular to the surface, the pivot point must be determined in advance. Appropriate calibration strategies of the movement system by using the line sensor in combination with a calibrated sphere were developed and will be presented.