On the development of a low-cost rigid borescopic fringe projection system

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. © 2015 SPIE