Optical design comparison of 60° eyepieces: one with a diffractive surface and one with aspherics

An optical design comparison is made between two 60 degrees field-of-view long-eye-relief eyepieces used for viewing a flat image-intensifier P-43 phosphor screen output. One eyepiece contains both spherical glass elements and plastic aspheric elements. The other eyepiece consists of spherical glass elements and a diffractive surface. Both optical designs were optimized by use of identical system constraints for size and weight. The eyepiece containing the diffractive surface provided an improved modulation transfer function performance and has been fabricated and tested. The fabricated lens characteristics and modulation transfer function performance closely matched the design expectations.