A multi-wavelength approach to structured illumination

Optical measuring methods based on the principle of structured illumination frequently apply phase shift evaluation for optical spatial coding. While these approaches allow for efficient and high-precision coding in many applications, they reach their limits in particular when different signal components are superimposed, which may occur due to multiple reflections on the workpiece surface. Therefore, in the present contribution, a novel approach in the field of structured illumination is presented, which implements spatial coding by a pattern sequence with increasing spatial frequency, based on similar approaches from the field of absolute distance interferometry. In addition to basics of the method, a first experimental result is presented, which shows that the method allows for a high-quality separation of superimposed signals.