US4240707A
Expired / Lapsed
US
⏱️ 0.0 years remaining
All-reflective three element objective
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1978-12-07
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Granted: 1980-12-23
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Expires: 1998-12-07
Abstract
Abstract A compact, all-reflecting optical system for viewing distant objects. The system comprises a negative convex secondary mirror placed between a positive concave primary mirror and a positive concave tertiary mirror. The system has an eccentric field of view in that the field of view lies entirely on one side of the optical axis, and because of this, the light travelling from the object to the image will pass entirely outside the secondary mirror, both when entering the system and when travelling from the tertiary mirror to the image. Accordingly, with the present invention, there is no central obstruction and no consequent restriction on field of view and power distribution between mirrors as is found in prior art all-reflecting systems.
Inventors
- 👤 William B. Wetherell
- 👤 David A. Womble
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:33
CPC Classifications
G; G02; G02B; G02B17/00; G02B17/02; G02B17/06; G02B17/0626; G02B17/0636
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
108 words
In an all-reflecting optical system for imaging distant objects, said optical system having an optical axis and comprising a primary mirror for receiving radiation from a distant object, and at least two additional mirrors for receiving radiation reflected from said primary mirror and for directing said radiation to an image plane for forming an image of said object thereon, the improvement comprising wherein said primary mirror, and hence said optical system, has an eccentric field of view in that said field of view is entirely on one side of said optical axis, and further wherein said image is also formed entirely on one side of said optical axis.
Claim 2
Dependent Claim
108 words
In an all-reflecting optical system for imaging distant objects, said optical system having an optical axis and comprising a primary mirror for receiving radiation from a distant object, and at least two additional mirrors for receiving radiation reflected from said primary mirror and for directing said radiation to an image plane for forming an image of said object thereon, the improvement comprising wherein said primary mirror, and hence said optical system, has an eccentric field of view in that said field of view is entirely on one side of said optical axis, and further wherein said image is also formed entirely on one side of said optical axis.
Claim 3
Dependent Claim
72 words
An all-reflecting optical system as recited in claim 1 wherein said primary mirror comprises a positive concave primary mirror, and wherein said at least two additional mirrors comprise a negative convex secondary mirror for receiving radiation reflected from said primary mirror, and a positive concave tertiary mirror for receiving radiation reflected from said secondary mirror and for directing said radiation to said image plane to form an image of said object thereon.
Claim 4
Dependent Claim
27 words
An all-reflecting optical system as recited in claim 2 wherein said image lies entirely on the opposite side of said optical axis from said field of view.
Claim 5
Dependent Claim
18 words
An all-reflecting optical system as recited in claim 3 wherein said secondary mirror lies on said optical axis.
Claim 6
Dependent Claim
33 words
An all-reflecting optical system as recited in claim 4 wherein said primary mirror and said tertiary mirror each comprise off-axis sections of surfaces which are rotationally symmetric with respect to said optical axis.
Claim 7
Dependent Claim
73 words
An all-reflecting optical system as recited in claim 2, wherein said primary, secondary and tertiary mirrors are positioned such that radiation, in travelling from the distant object to the image plane, passes entirely outside the secondary mirror both when entering the optical system and when travelling from the tertiary mirror to said image plane, such that there will be no central obstruction of the radiation and no restriction on the field of view.
Claim 8
Dependent Claim
124 words
An all-reflecting optical system for imaging distant objects, said optical system having an optical axis and comprising: a. a positive concave primary mirror for receiving light from a distant object; b. a negative convex secondary mirror for receiving light reflected from said primary mirror; and c. a positive concave tertiary mirror for receiving light reflected from said secondary mirror and for, in turn, reflecting said light to an image plane for forming an image of said object thereat, wherein d. said primary mirror, and hence said optical system, has an eccentric field of view in that said field of view is entirely on one side of said optical axis, and wherein said image is also located entirely on one side of said optical axis.
Claim 9
Dependent Claim
124 words
An all-reflecting optical system for imaging distant objects, said optical system having an optical axis and comprising: a. a positive concave primary mirror for receiving light from a distant object; b. a negative convex secondary mirror for receiving light reflected from said primary mirror; and c. a positive concave tertiary mirror for receiving light reflected from said secondary mirror and for, in turn, reflecting said light to an image plane for forming an image of said object thereat, wherein d. said primary mirror, and hence said optical system, has an eccentric field of view in that said field of view is entirely on one side of said optical axis, and wherein said image is also located entirely on one side of said optical axis.
Claim 10
Dependent Claim
60 words
An all-reflecting optical system as recited in claim 7 wherein said primary mirror is entirely on one side of said optical axis, said tertiary mirror is entirely on the opposite side of said optical axis, said secondary mirror is on said optical axis, and said image is entirely on the opposite side of said optical axis from said primary mirror.
Claim 11
Dependent Claim
30 words
An all-reflecting optical system as recited in claim 8 and further including stop means on said secondary mirror, said stop means being rotationally symmetric with respect to said optical axis.
Claim 12
Dependent Claim
33 words
An all-reflecting optical system as recited in claim 9 wherein said primary mirror and said tertiary mirror each comprise off-axis sections of surfaces which are rotationally symmetric with respect to said optical axis.
References Cited (Backward Citations)
US2306679A
Cited
US3460886A
Cited
US3674334A
Cited
US3748015A
Cited
US3821763A
Cited
US3811749A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-23 | 1984-06-23 | 1984-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-23 | 1988-06-23 | 1988-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-23 | 1992-06-23 | 1992-12-23 | $7700.00 | Window Closed / Lapsed |