Modal interaction matrix measurement for liquid-crystal corrector: precision evaluation

A modal interaction matrix (IM) measurement procedure is introduced for a liquid-crystal (LC) corrector for use in a phase-wrapping technique. Zernike modes are used to reconstruct the aberration wavefront and to drive the LC corrector. Usually the driving area is different from the active area. This difference induces a coupling effect on Zernike modes, which may have an impact on correction precision. In this paper the coupling effect is evaluated due to area difference and decentration, respectively. Then, a simulated turbulence wavefront is used to simulate the reconstruction process to evaluate its influence on reconstruction precision. We present simulation results that show that this method can be used to measure the IM with very high reconstruction precision under proper configuration. In order to maintain precision, the permissible eccentricity distance is also simulated with a result of no more than 5% of the LC corrector diameter.