Positioning system and lattice design for subaperture stitching interferometry

The demands on the quality of large aperture spherical and mild aspheric optical surfaces continue to rise in modern optical systems. Due to the aperture size of these surfaces measuring of their shape is quite problematic. One of the ways to measure these surfaces is the subaperture stitching interferometry. Its accuracy is highly depended on lattice design and accuracy of the positioning system. Optimal lattice design in relation to transmission element applied in interferometer together with coordinates calculation for the positioning system for measuring individual subapertures is the subject of this paper. To set the required orientation and position of the optical surface relative to the interferometer positioning system with six degrees of freedom was used. Three of them were realized as prismatic kinematic pairs and remaining three as revolution joints. In this paper the choice of coordinate systems for individual axes of the positioning system together with inverse kinematics used for setting the correct position and orientation of the optical surface are described.