White light interferometry (WLI): Optical 3D precision measurement technology in the production line

If roughness, ripple and shape are to be determined with high accuracy, today mainly tactile measuring methods are used. In the laboratory sector, white light interferometry (WLI) has also become established, allowing surfaces to be measured without contact and on a flat surface. However, neither tactile processes nor standard WLI can keep pace with the cycle times of automated production lines.

Thanks to the development of so-called lock-in image sensors and FPGA-based cameras, the measurement times of WLI sensors have been accelerated by a factor of 1000 in recent years. White light interferometry can thus be integrated directly into the production line. Long-term tests in the measuring laboratory (samples) will be replaced by automated inline tests (100).

The presentation uses a wide range of application examples to show the possibilities offered by the “industrial WLI” already today. The technology is particularly suitable for demanding conditions: glossy or transparent surfaces, sub-micrometer structures or recessed structures. The second part of the presentation explains the technology of the lock-in image sensors, as well as the special requirements and characteristics of industrial WLI. System- and component-level integration options are presented with examples (OEM).