Diffractive Optics Applied to Eyepiece Design.
ROCHESTER UNIV NY INST OF OPTICS
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In many visual instruments the eyepiece limits the overall optical performance of the system. Furthermore, inherent features of eyepieces make the design task quite difficult, thus conventional eyepieces often take complex forms. However, diffractive optics offers new design variables and thus greater degrees of freedom for the designer. In addition diffractive optics can be quite effective in reducing the weight and size of the system while also improving optical performance. The objective of this thesis is to present the role of diffractive optics in eyepiece design. A general description of eyepiece design is presented with special considerations to those areas in which diffractive lenses can be most beneficial. Several wide field of view, hybrid diffractive refractive eyepiece designs are presented. These are contrasted with examples of conventional wide field of view eyepieces, which are composed of several refractive elements and therefore can limit their usefulness in applications where size and weight are critical. The hybrid, three refractive element designs presented in this thesis offer wide field performance at least equivalent to the well-known 5-element Erfle eyepiece. In one design, the hybrid eyepiece weighs 70 less than the Erfle eyepiece, while having enhanced optical performance such as a 50 decrease in pupil spherical aberration and a 25 reduction in distortion. In addition, the hybrid eyepiece is comprised of a single, common glass type BK-7 which is less expensive than the glass types found in the Erfle design.