Diffractive optics applied to eyepiece design

Eyepieces often limit the overall optical performance of visual instruments and, because of the wide field-of-view and high-performance requirements, they present a well-known difficult design problem. Improvement of existing eyepieces is limited with the use of conventional design variables. We have designed and fabricated a hybrid diffractive-refractive wide-field (>60°) eyepiece that offers significant improvements over existing conventional eyepieces. The hybrid eyepiece consists of only three common-crown refractive elements and weighs 70% less than an Erfle-type eyepiece, while having enhanced optical performance such as a 50% decrease in pupil spherical aberration and a 25% reduction in distortion. Experimental modulation transfer function results are in excellent agreement with the theoretical performance.