Binary Adaptive Optics

In this paper, we introduce the concept of Binary Adaptive Optics (BAO). It is based on the addition of a phase value of  in some wavefront points to produce a new compensated wavefront with phase values contained into the (0,) interval. We have checked by computer simulations that the use of BAO is enough for successfully compensating strongly aberrated wavefronts. We used a Point Diffraction Interferometer (PDI) as wavefront sensor. The image obtained from the PDI, once binarized, represents the binary compensating phase map to be sent to the deformable mirror, the spatial light modulator, etc. The main drawback of the BAO system is that the maximum attainable Strehl ratio is 0.5. However, the BAO system has several advantages. The PDI sensor is easy to be manufactured, there is no need of any algorithm to reconstruct the wavefront surface and, finally, its dynamic range is infinite, which is particularly interesting in extremely large telescopes. A detailed analysis of the BAO performances has been carried out by computer simulation.