Designing, building, and testing of a hybrid wavefront sensor for adaptive optics

A bench top prototype hybrid wavefront sensor (HyWFS) has been designed and built. The construction and initial tests are reported in this paper. The sensor creates four images of the optical system pupil generated by a pyramid prism placed in a focal plane of the telescope, analogous to a pyramid wavefront sensor (PyWFS). A lenslet array forms a spot pattern of beacon images from each pupil in the manner of a Shack-Hartmann wavefront sensor (SHWFS). The intent of this work was to validate the concept presented by Guthery and Hart¹ in a low-cost prototype. The images produced by the hybrid system can be interpreted as either PyWFS data, yielding high sensitivity wavefront reconstruction with low dynamic range, or as SHWFS data, offering wavefront reconstruction with characteristically lower sensitivity but a large dynamic range. The HyWFS retains the desirable properties of both types without modulating the image on the pyramid prism.² For an initial system test, Zernike modes and Kolmogorov phase maps are placed on a deformable mirror (DM) and imaged with the HyWFS in a laboratory. The collected initial test images are then used to develop the final test reconstruction software and test setup. Final test software and system alignment is currently underway at the University of Arizona.