Fresnel zone plate with multiple layers of delay z

专利名称：Fresnel zone plate with multiple layers of delay zones
发明人：KAN CHENG
申请号：AU4518901
申请日：20001206
公开号：AU4518901A
公开日：
20010912
专利内容由知识产权出版社提供
摘要：The present Fresnel zone plate is comprised of a base plate (20), and a plurality of layers or orders (21, 22, etc.) of transparent phase delay zones arranged on the base plate. The zones of each succeeding order are narrower than those of the previous order, and are thinner to provide half the delay of the previous order. The radii of the zone boundaries are defined by the boundary formula Sj(n) = 2ROOT (b lambda n)/2, where j = integers representing order number, n = boundary number, b = focal length, and lambda = wavelength. The innermost zone boundary is boundary number 1. The phase delays introduced by the delay zones are defined by the delay formula (0.5+k) lambda , where j = integers representing order number, k = is preferably 0 but may be any integer, and lambda = wavelength. For example, with 3 orders of delay zones, the first order provides a 1/2 lambda delay, the second order provides a 1/4 lambda delay, and the third order provides an 1/8 lambda delay. Since each succeeding order is narrower than the previous order, a combination of 7 distinct delays are provided, from 1/8 lambda to 7/8 lambda , in 1/8 lambda increments. The delay increments are thus fine enough to correct most of the phase differences in the waves that passed through the zone plate to produce 97.5 % of the amplitude and 95 % of the intensity of an ideal lens. Alternative embodiments
include a concave zone plate (35-37), a zone plate with linear delay zones (40-42), a reflective zone plate (80-84), and a flat prism (85-87).
申请人：KAN CHENG
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