Design of a wide field diffractive landscape lens

The third-order aberrations of a diffractive optical element with paraxial zone spacings are derived as a function of aperture stop position. It is shown that by placing the stop in the front focal plane, coma and astigmatism are identically zero, assuming an infinitely distant object. In addition, since the element is diffractive, the Petzval sum is also zero. Modulation transfer function comparisons with other lenses are given. The correction of spherical aberration using an aspheric plate located in the aperture stop and nonmonochromatic imaging performance are discussed. The distortion of the resulting system is shown to be the proper amount for use as a Fourier transform lens. An estimate for the space-bandwidth product of this Fourier transform system is given.