Patent ID: 8755117
Filing Date: 2014-06-17
Classification: A61F,G02B,G02C

Abstract:
1. A manufacturing method of a diffraction lens other than an aphakic intraocular lens provided with a diffraction grating having a relief pattern extending concentrically on a surface of an optical material, the method comprising the steps of: adopting various types of reliefs whose first order diffracted lights give respective focal distances different from one another for the relief pattern; setting up a synchronous structure where (1) at least two reliefs are set to overlap with each other in at least a part of an area in a radial direction of the diffraction lens, and (2) grating pitches of an other relief are overlapped periodically with respect to every grating pitch of one relief having a maximum grating pitch among the reliefs set up in overlap in order to obtain a resulting relief pattern; and forming the resulting relief pattern on the surface of the optical material, wherein the various types of reliefs are arranged to satisfy a following equation: where A is a zone constant of the one relief, ‘a’ is a zone constant of the other relief, M is a zone number of the one relief, m is a zone number of the other relief, and N is a ratio of a focal distance of the one relief relative to that of the other relief, which is expressed as: