Gradial zone lens and method of fabrication
First Claim
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1. A method of making a diffractive lens, comprising the steps of:
- providing a mold having an axis and a mold cavity symmetrically surrounding the axis, the cavity having a desired geometry for at least one exterior surface of the diffractive lens;
spinning the mold about the axis;
injecting a first volume of a first optically transparent material into the cavity during the spinning, thereby placing the first volume at a periphery of the cavity to define a radially outer zone of the diffractive lens;
curing the first volume within the outer zone to at least partially solidify the material;
injecting a second volume of a second optically transparent material into the cavity during the spinning, thereby placing the second volume against an inner periphery of the outer zone to define a first radially inner zone of the diffractive lens;
curing the second volume within the first inner zone to at least partially solidify the material; and
repeating the injecting and curing steps to define and cure subsequent inner zones of the diffractive lens until the mold cavity is filled with concentric zones of cured material, the cross sectional areas of the zones and the first and second materials being chosen to produce an optical phase difference between adjacent zones of 2π
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the first and second optically transparent materials defining alternate ones of the zones.
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Abstract
Diffractive lenses having gradial zones (62, 70, 78, 90, 98, 106, 114) are formed by separately, sequentially spin casting and polymerizing successive radial zones of the lens to produce optical phase differences of 2π between adjacent gradial zones. Diffractive lenses may be molded in plano-plano(60), plano-concave (68) and plano-convex (76) geometries and also may be combined with conventional plano-plano (84), convex-convex (92), plano-concave (100) and plano-convex (108) refractive lenses.
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Citations
18 Claims
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1. A method of making a diffractive lens, comprising the steps of:
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providing a mold having an axis and a mold cavity symmetrically surrounding the axis, the cavity having a desired geometry for at least one exterior surface of the diffractive lens; spinning the mold about the axis; injecting a first volume of a first optically transparent material into the cavity during the spinning, thereby placing the first volume at a periphery of the cavity to define a radially outer zone of the diffractive lens; curing the first volume within the outer zone to at least partially solidify the material; injecting a second volume of a second optically transparent material into the cavity during the spinning, thereby placing the second volume against an inner periphery of the outer zone to define a first radially inner zone of the diffractive lens; curing the second volume within the first inner zone to at least partially solidify the material; and repeating the injecting and curing steps to define and cure subsequent inner zones of the diffractive lens until the mold cavity is filled with concentric zones of cured material, the cross sectional areas of the zones and the first and second materials being chosen to produce an optical phase difference between adjacent zones of 2π
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the first and second optically transparent materials defining alternate ones of the zones. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A diffractive lens comprising a plurality of individual, concentric annular zones of material, the zones extending from a central radially innermost zone to a concentric radially outermost zone, the cross sectional areas of the plurality of concentric annular zones and the indicies of refraction of the plurality of concentric annular zones being chosen so that first and second zones of material of said plurality of individual concentric annular zones of material have a first and second index of refraction, respectively, and other of said plurality of individual concentric annular zones of materials have alternately repeating first and second indicies of refraction to produce an optical phase difference between adjacent zones of 2π
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whereby the alternating zones function as a radial grating to diffract light incident upon the lens. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification