New improvement in calibration strategy for Structured-Illumination Macroscopy

With Structured-Illumination Microscopy (SIM), the 3D-topography of technical surfaces can be acquired with an uncertainty below 10nm and with high angular dynamics of up to +-70°, if implemented with a high NA objective and diffraction-limited PSF. We want to scale up the principle for macroscopic objects. However, for a macroscopic field, such a lens is not available for reasonable cost. As a consequence, in an up-scaled SIM, the unavoidable aberrations will cause lower local precision and a reduced global accuracy (retrace error). To solve these problems, we are developing a novel model-free calibration strategy, which relies on the compensation of the “retrace error”. A proof of principle implementation has shown a two-fold reduction of global accuracy [1]. Besides of significant improvement of the mechanical components, we introduced a new crucial feature: We combine SIM with slope-measuring microdeflectometry [2] to achieve both an improved global accuracy and a better local precision. [1]Yang, DGaO, A10, 2012 [2]Häusler, “Microdeflectometry - a novel tool to acquire 3D microtopology with nanometer height resolution”, Opt. Lett., 2008