A study of variable subaperture size for astronomical adaptive optics

We examine the utility of a wavefront sensor with a variable subaperture size for astronomical adaptive optics. A numerical analysis, based on wavefront variance and Strehl ratio expressions, was used to find the optimal subaperture size and wavefront sensor integration time for several case studies. The results show that a relatively smaller subaperture size can provide improved performance if the atmospheric coherence length r(0) is also small and the source is relatively bright. Similarly, a larger subaperture size can improve performance if r(0) is also large, the source is relatively dim, and the atmospheric temporal variation is relatively slow. These results suggest that a reconfigurable wavefront sensor could have utility for certain situations where conditions vary from nominal values.