A comparison of the wavefronts recorded simultaneously by a Shack-Hartmann and a Distorted Grating Wavefront Sensor (DGWFS) has been completed. The DGWFS is a phase diversity/wavefront curvature type of sensor using a grating to generate the multiple image planes. Data were collected under simulated propagation conditions using the Advanced Concept Laboratory at Lincoln Laboratory. The sensors were arranged such that both recorded a time varying sample of the wavefront at exactly the same time. Dynamic and static comparisons of the two sensors under conditions that ranged from a benign path, D/r0 = 2, to a propagation condition with significant scintillation, D/r0 =50, were completed.
The data show that the two techniques measure static, low amplitude, on the order of a few waves, aberrations with little difference. Under conditions where there are significant aberrations, the wavefronts measured by the two sensors show notable differences with the DGWFS exhibiting a smoothed, low passed, rendition of the wavefront. As the aberrations increase to produce scintillated condition the differences become more pronounced.