Tuning Structured Illumination Microscopy (SIM) for the Inspection of Micro Optical Components

With the concept of "structured illumination microscopy (SIM)", introduced at the DGaO-Conference 2009, it is possible to quantitatively acquire the 3D-topography of rough and smooth surfaces with extremely high longitudinal resolution (better than 10 nm for smooth surfaces). SIM is incoherent, information efficient and needs simple technology. By means of a high aperture the system is furthermore capable of measuring steep slopes up to 60 degrees, even for smooth objects. The acquired images have SEM-like quality. These features make the sensor attractive to measure micro optical components. Optical components, however, often require a global accuracy better than 100 nm. This is difficult to achieve, because the global deviations depend on the field and on the slope of the surface. We present an error analysis of SIM and identify the major deviations. Methods to compensate for the inevitable technological imperfections will be discussed. We present SEM-like (quantitative) images of smooth and rough micro-objects.