Experimental study for a field diversity phase retrieval wavefront sensing approach

Field diversity wavefront sensing is one of the image-based wavefront methods, where the intensity measurements with phase diversities are directly obtained from different field positions of one image, without the need for any additional instruments (e.g., beam splitter) or operations (e.g., focus adjusting). While the phase diversities between different positions are unknown to us, this method is realized based on an in-depth understanding of the net aberration fields induced by misalignments and figure errors. However, this novel, to the best of our knowledge, image-based wavefront sensing method has not been experimentally studied, which restricts the application and promotion of this method. In this work, the analytic gradient of the field diversity wavefront sensing is derived, and the accuracy and effectiveness of this method in the active alignment of real three-mirror anastigmatic (TMA) optical systems are systematically demonstrated. The results show that this method can be applicable to wavefront sensing of large space telescopes.