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Geometry measurements are very important to monitor a machine part's health and performance. Optical measurement system have several advantages for the acquisition of a parts geometry: measurement speed, precision, point density and contactless operation. Measuring parts inside of assembled machines is also desirable to keep maintenance cost low. The Raspberry Pi is a small and cost efficient computer that creates new opportunities for compact measurement systems. We have developed a fringe projection system which is capable of measuring in very limited space. A Raspberry Pi 2 is used to generate the projection patterns, acquire the image and reconstruct the geometry. Together with a small LED projector, the measurement system is small and easy to handle. It consists of off-the-shelf products which are nonetheless capable of measuring with an uncertainty of less than 100 µm.

Quality control is an important aspect of modern production processes. Obtaining quantitative information not only helps to ensure the function of machinery and products, but also enables cost reduction by feedback control of process parameters. A multitude of modern industrial applications feature an increasing amount of highly integrated machinery, resulting in a requirement for new measuring devices. Two new measuring systems are presented for in-situ inspection tasks in confined spaces. A combination of endoscopy techniques with structured illumination enables capturing areal 3-D geometry information of functional elements in integrated machinery. Depending on the requirements for inspection, either rigid or flexible image guides may be used to transport the structured light patterns. While a flexible endoscope allows for a more flexible positioning of the sensor head, its resolution is limited by the number of individual fiber cores. Alternatively, if constraints on the versatility of sensor positioning can be accepted, rigid endoscopes feature higher image quality. Both approaches are described in detail and compared based on evaluations on features of a calibrated micro contour standard.

Examining the geometry of complex industrial free form objects, like a blade integrated disk (blisk) of a jet engine compressor, is currently subject to research. High measurement precision and speed are required and the complex geometry poses a challenge for state of the art measurement systems. In order to fulfill typical inspection requirements, the fringe projection methodology was adapted in this work to accomplish the task of fast and precise geometry examination. A low cost borescopic fringe projection system for 3D shape measurement based on consumer electronics combined with state of the art optics was developed. Nevertheless, it is able to provide measurement uncertainties comparable to professional systems. We are using a portable consumer LED-beamer, which we have modified to fit the optics of the borescope and a Raspberry Pi single-board computer with a 5 megapixel camera to capture the fringe patterns. With this setup and fringe projection algorithms, which have been developed by this institute over the last years, we were able to perform high quality measurements while still being suitable for a compact inspection system. Measurements with high point densities are possible even in narrow areas of parts with complex geometries like blisks. The measuring system and first measurement results will be presented at the conference.