Measurement technique allows survey of 3D micro objects
The decisive difference between fringe light projection and "normal" measurement techniques is that fringe light allows non-contact measurement. Thus, objects can be surveyed without negatively affecting delicate surfaces. But surveying micro objects poses specific challenges: In order to achieve an accuracy of 1 micrometre within a volume of 1 cubic centimetre, 100 billion positions on that object have to be measured. Researcher Daniel Härter from the Institute of Microsystem Technology of the Freiburg University succeeded in transferring the non-contact measurement technique into microscopic dimensions.
In his study, titled "Triangulative Micro Mark Projection", the researcher introduces his measurement system for contact-less object survey. Härter modified the fringe light projection in a way that it utilizes punctiform light marks instead of light strips. It combines a positioning device with an optical sensor system which makes use of active triangulation und thus enables three-dimensional survey of two miniaturised components, composing different partial views to a total view in a common system of coordinates. The sensor system features an exactness of 1.45 micrometres in which all measurement values can practice-oriented be ascribed to the known diameter of a calibration sphere for high absolute accuracy.
The technique is already integrated into machines which, for example, enable non-destructive survey of biological surfaces for research purposes or, as another application, can be used for quality control in tiny components such as gear wheels, micro motors or medical instruments.
These days, Härter was honoured for his achievement with the annual award of the Forum Angewandte Informatik und Mikrosystemtechnik (Forum for Applied Computer Sciences and Micro System Technology, FAIM).
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