The standard zone plate assumes that the shortest ray connecting a radiation source and a detection point has a phase of 0 deg thereby defining a reference phase. Here we examine the experimental consequences of varying this reference phase from 0 deg to 360 deg. It is concluded that reference phase is an intrinsic and useful property of zone plates.
Cite
@article{arxiv.physics/0303002,
title = {Reference Phase of Fresnel Zone Plates},
author = {G. W. Webb},
journal= {arXiv preprint arXiv:physics/0303002},
year = {2007}
}