Critical alignments in plane mirror interferometry

A model of two dimensional in-plane metrology using plane mirror interferometry is developed based on an archetype measuring configuration. The purpose of the model is to define and study the key factors limiting the accuracy of this system. Geometric errors are studied under the assumption that component motions and transducers are linear, but not necessarily in alignment. Abbe offsets depend on higher order terms and are neglected in the first order analysis. This study provides some interesting clarifications of which alignment errors are most important and what is meant by cosine error and alignment error.