3D imaging: Wave front sensing utilizing a birefringent crystal

Utilizing a rotatable thin birefringent crystal and two polarizers, the three-dimensional (3D) wave front of any light wave can be measured conveniently. In first experiments phase-front distortions as small as 15 mu m are detected with a dynamic range of 3 mm and a spatial resolution of 50 mu m. Such a dynamic range and spatial resolution exceed the performance of conventional wave front sensors of, e.g., the Shack-Haltmann type, significantly. Furthermore, the new system is rather insensitive against mechanical instabilities in opposition to interferometric and holographic techniques.