Abstract
Atmospheric turbulence in the optical path of incoming stellar light transforms a plane wavefront into a distorted wavefront. This leads to loss of resolution achievable in a telescope. The correction of these distortions is the goal of adaptive optics. We are designing an experiment to recreate the effects of turbulence on an optical bench. This experiment aims to reproduce the effects observed in an artificial sodium laser star when viewed by a 30m class telescope. The edge of such large telescopes see the sodium artificial star as an elongated rather than a circle. In the bench experiment the turbulence distortions are achieved by directing the light beam through a glass plate whose surface is etched to imitate the phase distortions caused by the atmosphere, this plate is called a phase screen. Phase screens are made much bigger than the incident beam of light and we move this phase plate to simulate the effect of a changing atmosphere. To test new turbulence patterns one needs several different phase screens, which are expensive and hard to make. Our work involves computing numerical simulations of turbulence and testing algorithms to correct the phase distortion.We would then like to test these algorithms on our bench before testing on the telescope. To make these tests more realistic we would like to apply the same simulated turbulence patterns to our phase screen. This is almost impossible to do with phase screens, therefore we are planning to replace phase screens with spatial phase modulators that can be programmed to introduce a phase shift to the incident light at a time resolution of milliseconds. Integration of spatial phase modulators in optical benches as phase screens will allow for much more flexible experiments permitting a perfect correlation between the numerical simulations and the physical experiments.
