Fiber-optic interference fringe projection for 3D measurement

This work presents experimental and simulation results of a 3D measurement concept based on fiber-optic interference fringe projection. A demonstrator system which is able to adjust different optical and mechanical parameters like polarisation angle, wavelength, triangulation angle and the distance between the fibers is described. The results of parameter variation studies are discussed along with possible applications in the field of micro-optical 3D measurement systems like borescopes. The optical properties of the measured object show a significant influence on the measurement results. To get a reliable accuracy of 3D monitoring, the surface needs to exhibit a Lambertian scattering behaviour with low correlation length. Therefore, the experiments were prepared with different structures in a dimension range from 40 µm to 400 µm with various scattering properties. The analysis of the obtained results demonstrates the practical limitations of a triangulation based measurement system based on fiber–optic interference fringe projection. These limitations are strongly connected to the surface correlation length and roughness.