... Since image restoration algorithms are highly sensitive to the accuracy of the calculated PSF, a significant portion of our research effort is devoted to accurately modeling the PSF which is a highly non-linear problem. Our approach is based on analytical modeling of the wavefront phase using Zernike polynomials. ... In the Fourier domain, we scale the phase map by an observed PSF to more accurately account for the HST/FOC combination. ... The final result is an improved estimate of the phase map. ...