Exploring the coherence function for optical metrology and beyond

I will report on several strategies to exploit the structure of the coherence function for optical metrology and wave field analysis in general. For the case of optical metrology, I will show that properties like the surface topology or refractive index distributions can be determined by solely investigating the coherence function of light that has previously interacted with the specimen under test. Since the coherence function can be measured by a simple shear interferometer, this suggests that a large variety of metrology tasks can be accomplished by a common-path architecture. A prime advantage of this approach is the combination of interferometric precision with inherent mechanical robustness. Furthermore, because a shear interferometer is essentially an imaging system that provides a twin-image, methods based on sensing the coherence function are very flexible and largely independent from the distance between sensor and object.