Misalignment study for a Dove prism employing exact ray trace

Abstract

We are designing, fabricating and characterizing a Dove prism for interferometric use. In a previous work, we determined the prism tolerance to manufacturing errors. When the manufacturing tolerance of the angles is maintained within ± 0.35 arc sec, the maximum wave-front deviation is better than λ/10 at 633 nm. We evaluated the change in the image quality introduced by this performance deterioration. In this work, we study the optical (angular) and the error-induced misalignments, caused by a real Dove prism, using exact ray trace. A Dove prism is aligned when the interferometer optical axis and the prism axis are collinear. We determine the tolerance to misalignment of the Dove prism for its incorporation in a Rotationally-Shearing Interferometer (RSI). We show that it is possible to reduce the wave-front deviation caused by base-angle errors with a specific optical misalignment. The misalignment analysis of a Dove prism, with an index of refraction of 1.515, shows that to ensure a maximum OPD of λ/10 (at 633 nm) the tolerance to misalignment must be ± 0.33 arc sec.