Fringe light projection offers potential for micro-3D survey

A researcher from University of Freiburg has demonstrated how fringe light projection can be used to measure the dimension of 3D objects in the micrometer range. Fringe light projection, which is a well-established technique to survey the geometry of relative large objects such as tools or even complete cars, has now been found to have prospective applications in the world of 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碌m within a volume of one cubic centimeter, 100 billion positions on that object have to be measured. Researcher Daniel Harter 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. Harter modified the fringe light projection in a way that it uses punctiform light marks instead of light strips. It combines a positioning device with an optical sensor system that makes use of active triangulation und thus enables 3D survey of two miniaturized components, composing different partial views to a total view in a common system of coordinates. The sensor system features an exactness of 1.45碌m 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 being 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.

- Christoph Hammerschmidt
??EE Times Europe