US4714307A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Catadioptric infrared lenses
Assignee: Qioptiq Ltd
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Filing: 1986-07-10
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Granted: 1987-12-22
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Expires: 2006-07-10
Abstract
Abstract An apochromatic catadioptric lens is provided which can operate in the 3 to 5 and the 8 to 12 micron wavebands. The lens comprises a primary mirror having an opening and a Mangin secondary mirror for directing light of the required wavebands through the opening. In the light paths between the primary mirror and Mangin secondary mirror are a pair of refracting lens elements of optically transmissive materials different from each other and from that of the Mangin secondary mirror. Preferably, the Mangin secondary mirror is of germanium, the refracting lens element of the pair nearer the Mangin secondary mirror is of zinc sulphide and the refracting lens element of the pair further from the Mangin secondary mirror is of zinc selenide. The invention also extends to an afocal telescope of non-Galilean form incorporating such a lens.
Inventors
- 👤 John M. Palmer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:13
CPC Classifications
G; G02; G02B; G02B17/00; G02B17/08; G02B17/0896; G02B13/00; G02B13/14; G02B13/146; G02B17/0804; G02B17/0808; G02B17/0852; G02B17/0856
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
78 words
A catadioptric lens comprising a primary mirror having an opening, a Mangin secondary mirror of a first optically transmissive material, and a pair of refracting lens elements respectively of second and third optically transmissive materials different from each other and from said first optically transmissive material, said pair of elements being disposed in the light paths between the primary mirror and the Mangin secondary mirror and between the Mangin secondary mirror and the opening in the primary mirror.
Claim 2
Dependent Claim
78 words
A catadioptric lens comprising a primary mirror having an opening, a Mangin secondary mirror of a first optically transmissive material, and a pair of refracting lens elements respectively of second and third optically transmissive materials different from each other and from said first optically transmissive material, said pair of elements being disposed in the light paths between the primary mirror and the Mangin secondary mirror and between the Mangin secondary mirror and the opening in the primary mirror.
Claim 3
Dependent Claim
28 words
A lens according to claim 1 operative over a 3 to 12 micron infra-red waveband in which the three different materials are germanium, zinc sulphide and zinc selenide.
Claim 4
Dependent Claim
45 words
A lens according to claim 2 in which the Mangin secondary mirror is of germanium, the element of the pair nearer the Mangin secondary mirror is of zinc sulphide, and the element of the pair further from the Mangin secondary mirror is of zinc selenide.
Claim 5
Dependent Claim
26 words
A lens according to claim 1 in which the pair of elements are closely spaced apart and of meniscus form concave towards the Mangin secondary mirror.
Claim 6
Dependent Claim
26 words
A lens according to claim 1 in which the Mangin secondary mirror has a convex front surface and an externally concave (internally convex) back reflecting surface.
Claim 7
Dependent Claim
28 words
A lens according to claim 1 in which one of the elements of the pair of elements is of positive power and the other is of negative power.
Claim 8
Dependent Claim
33 words
A lens according to claim 6 in which the element of the pair further from the Mangin secondary mirror is negatively powered and the element nearer the Mangin secondary mirror is positively powered.
Claim 9
Dependent Claim
25 words
A lens according to claim 1 comprising a further refractive lens element of optically transmissive material at or near the opening in the primary mirror.
Claim 10
Dependent Claim
17 words
A lens according to claim 8 in which the further refractive lens element is of positive power.
Claim 11
Dependent Claim
23 words
A lens according to claim 9 in which the further refractive lens element is of meniscus shape convex towards the Mangin secondary mirror.
Claim 12
Dependent Claim
23 words
A lens according to claim 8 in which, for the 3 to 12 micron waveband, the further refractive lens element is of germanium.
Claim 13
Dependent Claim
20 words
An afocal telescope of non-Galilean form including a catadioptric lens according to claim 1 and associated with an eyepiece system.
Claim 14
Dependent Claim
20 words
A telescope according to claim 12 in which the eyepiece system comprises three refractive lens elements of optically transmissive material.
Claim 15
Dependent Claim
20 words
A telescope according to claim 12 in which, for the 3 to 12 micron waveband, the transmissive material is germanium.
Claim 16
Dependent Claim
50 words
A telescope according to claim 13 in which the three refractive lens elements comprise a negatively powered front element (i.e. towards the catadioptric lens), a central positively powered element having a convex rear surface, and a back positively powered element with a convex front surface and a curved rear surface.
Claim 17
Dependent Claim
34 words
A telescope according to claim 15 in which the negatively powered element is biconcave, the central positively powered element is meniscus in shape, and the back positively powered element is also meniscus in shape.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-12-21 | 1991-06-22 | 1991-12-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-12-21 | 1995-06-22 | 1995-12-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-12-21 | 1999-06-22 | 1999-12-22 | $7700.00 | Window Closed / Lapsed |