Pupil plane filtering provides a convenient technique for modifying the point spread function. Such modifications are
used in many practical applications that require enhancement of selective frequency band in images. Also, in many new
imaging paradigms, acquisition of 3D image information calls for tailoring of the 3D point spread function. This can be
achieved by suitable pupil plane filtering, preferably by phase filters. By using a pupil plane filter with an array of
concentric annuli, the point spread function can be tailored in a fashion such that a narrow central lobe is surrounded by
neighboring lobes of low amplitude, with one or more lobes of high amplitude spaced far away from the center. In our
study we intend to explore the use of phase annuli as pupil filters in tailoring of both transverse and axial resolution.
Determination of such phase filters in accordance with a set of prespecified requirements for amplitude/intensity
distribution around the focus constitutes a problem of nonlinear optimization. This paper reports some results of our
preliminary investigations on an application of evolutionary programming in solving this problem to obtain globally or
quasi-globally optimum solutions.