A hybrid wavefront sensor: combining Shack-Hartmann and pyramid wavefront sensors to enable high dynamic range and sensitivity

We are developing a Hybrid Wavefront Sensor (HyWFS) which combines the high dynamic range of a Shack-Hartmann wavefront sensor and the high sensitivity of an unmodulated pyramid wavefront sensor. In our prototype light is focused on a crossed roof prism and subsequently passed through a lenslet array creating four arrays of focal points corresponding to each of the four pupils. This allows us to simultaneously perform both Shack-Hartmann and pyramid wavefront sensing analyses on aberrated wavefronts. This hybrid method would allow continuous wavefront corrections using a deformable mirror during turbulent events that would saturate an unmodulated pyramid wavefront sensor functioning alone. Experimental results confirm the HyWFS has high sensitivity to weak aberrations while maintaining robustness against stronger aberrations due to the amalgamation of wavefront sensing techniques.