Telephoto-lens-based Optical Differentiation Wavefront Sensor for freeform metrology

Abstract

We report an Optical Differentiation Wavefront Sensor based on a telephoto lens system and binary pixelated filters. It provides a five-fold reduction in the system length compared to a 4 f system with identical effective focal length. Measurements of phase plates with this system are compared to measurements performed with a commercial low-coherence interferometer. The telephoto-lens-based system can measure wavefronts with accuracy better than λ/ 10 Root Mean Squared (RMS) at λ =633 nm. Experimental investigation shows that the system has a high tolerance to components alignment errors.