Multifocal contact lens
First Claim
1. A multifocal contact lens having diffractive power in which at least one image at one order is produced by diffraction and that image as seen by the eye through one part of the lens is differentiated from the same image at the same order as seen by the lens through another part of the lens by having a different intensity of light.
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0 Petitions
Accused Products
Abstract
A multifocal contact lens has diffractive power arising from a series of concentric zones each providing an asymmetric retardation of light across the zone width to direct light predominantly into a required order and sign of diffraction. At least some of the concentric zones are shaped so that the step height varies so that it is different in one region (A) of the lens from that in another region (B), whereby the intensity of light associated with an image observed by diffraction at one order in that region (A) of the lens is greater than the light intensity associated with the same image when observed at the same order through another region (B) of the lens.
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Citations
20 Claims
- 1. A multifocal contact lens having diffractive power in which at least one image at one order is produced by diffraction and that image as seen by the eye through one part of the lens is differentiated from the same image at the same order as seen by the lens through another part of the lens by having a different intensity of light.
- 3. A multifocal contact lens having both refractive and diffractive power, the diffractive power being provided by asymmetric zone plate surfaces and being distributed over a viewing area of the lens in such a way that the intensity of the image focussed by the diffractive power in one part of said area is greater than that in another part.
- 5. A multifocal contact lens having diffractive power which comprises a plurality of concentric zones arranged so as to cause diffraction of light transmitted through the lens, each zone providing an asymmetric retardation of light across the zone width in a manner which directs light of a design wavelength predominantly into one required order and sign, at least some of the concentric zones being shaped so that the step height of each zone changes so that it is different in one region of the lens from that in another region of the lens, whereby the intensity of light associated with an image observed by diffraction at one order in that region of the lens is greater than the light intensity associated with the same image when observed at the same order through any other portion of that lens.
- 15. A method of manufacturing a multifocal contact lens having diffractive power which comprises interposing a mask shaped to provide a zone plate pattern on the finished lens between a laser source and the lens blank and in addition, providing means to modulate the ablative effect of said laser over the area of the mask, whereby a zonal plate pattern is formed by ablation on the surface of the lens blank.
Specification