Phase retrieval and adaptive optics correction for systems with diffractive surfaces

Adaptive optics (AO) is a powerful technique for correcting extrinsic aberrations, such as those caused by atmospheric turbulence or biological sample thickness variations, by using measured phase information and a wavefrontcorrecting element. To extend AO techniques to systems with diffractive surfaces, considerations need to be made for additional components of the measured phase that are attributable to diffraction from the object and are not a part of the extrinsic aberration. For example, light reflected froma diffractive surface of an optical storage disk contains an additional phase due to the diffracted orders fromthe grating-like structure of the data tracks. In this work, a modifiedGerchberg algorithm is presented as a viable method of phase retrieval to detect the total aberration, and correction for extrinsic aberrations is shown for light reflected from a grating. An experimental microscope system demonstrates successfulAOcorrection, thus verifying simulation results.