Improving the performance of the modal holographic wavefront sensor by adapting to prevailing turbulence conditions: experimental verification

The modal holographic wavefront sensor offers a promising alternative to established wavefront sensing techniques. Since the strengths of individual aberration modes are directly measured, there is no need for time-consuming signal processing and wavefront reconstruction. Bandwidths up to three orders of magnitude higher than those of commercial wavefront sensors can in principle be achieved. However, in practice the accuracy of measurements is compromised by intermodal crosstalk, which arises when the wavefront exhibits additional aberrations to those encoded in the modal wavefront sensor. This issue is particularly prominent when measuring wavefronts disturbed by atmospheric turbulence. To mitigate the effects of intermodal crosstalk, a procedure to optimize the sensor design for prevailing atmospheric turbulence conditions has been proposed. In this paper, we experimentally investigate the effectiveness of this method. We describe the fabrication of a holographic wavefront sensor consisting of a thin phase transmission holographic grating. In an optical testbed, defined wavefront deformations are generated using a spatial light modulator, and the wavefront sensor is used to measure these disturbances. The measurement error is determined for different sensor designs.