Title:
【発明の名称】ガス透過性硬質コンタクトレンズおよびその製造方法
Document Type and Number:
Japanese Patent JP3114225
Kind Code:
B2
Abstract:
A lens having a refractive power arising from the shape, curvature and material of the lens, and a diffractive power, the diffractive power being produced by a diffractive means with steps formed by cutting one of the surfaces of the lens with a diamond tool, characterised in that the lens is a single vision rigid gas permeable lens in which the power of the lens is determined by a combination of the refractive power and the diffractive power, the steps of the diffractive means have a gradient steeper than 45%, and the diffractive means is one in which the step heights when multiplied by the refractive index difference between the lens material and the tear film provide an optical path difference substantially equivalent to one wavelength of light close to the centre of the human visual response or some integral multiple thereof.
Inventors:
Michael harold freeman
William E. Mayers
William E. Mayers
Application Number:
JP8423691A
Publication Date:
December 04, 2000
Filing Date:
April 16, 1991
Export Citation:
Assignee:
Pb H Diffractive Lenses Limited
International Classes:
G02B5/18; G02B1/04; G02C7/04; (IPC1-7): G02C7/04
Domestic Patent References:
| JP192719A | ||||
| JP228615A |
Attorney, Agent or Firm:
Takehiro Chiba (3 others)