Theoretical And Experimental Evaluation Of Isoplanatic Patch Size For Adaptive Optics

Correlation functions of the Zernike-polynomial expansion coefficients of turbulence induced aberrated wavefronts are presented and experimentally confirmed using laboratory-generated Kolmogorov turbulence. These functions are convenient for characterizing the anisoplanatic error for adaptive optics. The isoplanatic patch-size of such systems is evaluable according to their specific working parameters. We find, for example, with a 4 m telescope working at 3.5 μm and sensing the wavefront phase fluctuation on 20 Zernike polynomials, an isoplanatic patch about 22 arcseconds wide.