US5151826A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fresnel lens
Assignee: Combined Optical Industries Ltd
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Filing: 1991-03-08
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Granted: 1992-09-29
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Expires: 2011-03-08
Abstract
Abstract A fresnel lens in which each of the facets is so dimensioned and configured that the distance between the facet and a focal point of the lens is (n+k) λ where n is an integer, λ is the wavelength of the radiation passing through the lens, and k is a fraction between 0 and 1 which is substantially constant for any facet over the entire face of the lens. Preferably the lens comprises a plurality of zones, each comprising a number of facets, the integer n being constant for each facet of each said zone, but being different for facets of different zones.
Inventors
- 👤 Ian K. Pasco
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 05:51
CPC Classifications
G; G02; G02B; G02B3/00; G02B3/02; G02B3/08; G08; G08B; G08B13/00; G08B13/18; G08B13/189; G08B13/19; G08B13/193
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
131 words
A fresnel lens comprising a plate having a plurality of zones, a plurality of facets in each zone so dimensioned and configured that the distance between a face of the lens for each facet and a focal point of the lens on the same side thereof as said face is (n+k) λ where n is an integer, λ is the wavelength of radiation passing through the lens and k is a fraction between 0 and 1 which is substantially constant for every facet across the entire face of the lens, the integer n being constant for all the facets of each zone, with the integer n being different for the facets of different zones, respectively, whereby the radiations from all of said zones arrives at said focal point substantially in phase.
Claim 2
Dependent Claim
131 words
A fresnel lens comprising a plate having a plurality of zones, a plurality of facets in each zone so dimensioned and configured that the distance between a face of the lens for each facet and a focal point of the lens on the same side thereof as said face is (n+k) λ where n is an integer, λ is the wavelength of radiation passing through the lens and k is a fraction between 0 and 1 which is substantially constant for every facet across the entire face of the lens, the integer n being constant for all the facets of each zone, with the integer n being different for the facets of different zones, respectively, whereby the radiations from all of said zones arrives at said focal point substantially in phase.
Claim 3
Dependent Claim
23 words
A fresnel lens according to claim 1, wherein the facets are disposed on the face of the lens nearest the said focal point.
Claim 4
Dependent Claim
16 words
A fresnel lens according to claim 1, wherein each facet is configured as a aspheric curve.
Claim 5
Dependent Claim
30 words
A fresnel lens according to claim 1, wherein the lens is generally of substantially uniform thickness, and the width of a facet is different at different points across the lens.
Claim 6
Dependent Claim
35 words
A fresnel lens according to claim 1, wherein the lens is moulded from high density polyethylene, and the lens is thickest at a substantially central feed point and overall decrease in thickness towards its edges.
Claim 7
Dependent Claim
24 words
A fresnel lens according to claim 1, constructed and arranged for use with infra-red radiation in the wavelength range of 7 to 14 μm.
Claim 8
Dependent Claim
23 words
A fresnel lens according to claim 1 wherein the value of n for each successive zone is changed by a unitary integral value.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-09-29 | 1996-03-30 | 1996-09-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-09-29 | 2000-03-30 | 2000-09-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-09-29 | 2004-03-30 | 2004-09-29 | $7700.00 | Window Closed / Lapsed |