US4598981A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Wide-angle flat field telescope
Assignee: National Aeronautics and Space Administration
•
Filing: 1985-02-05
•
Granted: 1986-07-08
•
Expires: 2005-02-05
Abstract
Abstract An unobscured three mirror wide-angle telescopic imaging system comprised of an input baffle which provides a 20 DEG (Y axis)x30 DEG (X axis) field of view, a primary mirror having a convex spherical surface, a secondary mirror having a concave ellipsoidal reflecting surface, a tertiary mirror having a concave spherical reflecting surface. The mirrors comprise mirror elements which are offset segments of parent mirrors whose axes and vertices commonly lie on the system's optical axis. An iris diaphragm forming an aperture stop is located between the secondary and tertiary mirror with its center also being coincident with the optical axis and being further located at the beam waist of input light beams reflected from the primary and secondary mirror surfaces. At the system focus following the tertiary mirror is located a flat detector which may be, for example, a TV imaging tube or a photographic film. When desirable, a spectral transmission filter is placed in front of the detector in close proximity thereto.
Inventors
- 👤 Kenneth L. Hallam
- 👤 Barton J. Howell
- 👤 Mark E. Wilson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:01
CPC Classifications
G; G02; G02B; G02B17/00; G02B17/02; G02B17/06; G02B17/0626; G02B17/0636
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
267 words
An all-reflective wide-angle unvignetted flat-field telescopic imaging system, comprising: baffle means for defining a predetermined relatively wide-angled field of view; primary mirror means comprising a segment of a first spherical mirror and having a convex spherical reflecting surface positioned relative to said baffle means to receive and reflect input light beams received from a remote source; secondary mirror means comprising a segment of an ellipsoidal mirror having a concave ellipsoidal reflecting surface positioned relative to said primary mirror means to receive and reflect light beams from said convex spherical reflecting surface of said first spherical mirror; tertiary mirror means comprising a segment of a second spherical mirror and being positioned relative to said secondary mirror means to receive light from said concave ellipsoidal reflecting surface thereof and reflect said light beams to a planar focal surface; aperture stop means located intermediate said secondary and tertiary mirror means; said segments of said primary, secondary and tertiary mirror means being positioned offset from a common optical axis in a first direction and in alignment therewith in a second direction, and wherein the centers of said first and second spherical mirrors, the foci of said ellipsoidal mirror and the center of said aperture stop means are substantially coincident with said optical axis, whereby said light beams pass through the system unobscured by any of said mirror segments; and light detector means being positioned in front of the concave spherical reflecting surface of said tertiary mirror means at the location of said planar focal surface and clear of light being received by said tertiary mirror means from said secondary mirror means.
Claim 2
Dependent Claim
267 words
An all-reflective wide-angle unvignetted flat-field telescopic imaging system, comprising: baffle means for defining a predetermined relatively wide-angled field of view; primary mirror means comprising a segment of a first spherical mirror and having a convex spherical reflecting surface positioned relative to said baffle means to receive and reflect input light beams received from a remote source; secondary mirror means comprising a segment of an ellipsoidal mirror having a concave ellipsoidal reflecting surface positioned relative to said primary mirror means to receive and reflect light beams from said convex spherical reflecting surface of said first spherical mirror; tertiary mirror means comprising a segment of a second spherical mirror and being positioned relative to said secondary mirror means to receive light from said concave ellipsoidal reflecting surface thereof and reflect said light beams to a planar focal surface; aperture stop means located intermediate said secondary and tertiary mirror means; said segments of said primary, secondary and tertiary mirror means being positioned offset from a common optical axis in a first direction and in alignment therewith in a second direction, and wherein the centers of said first and second spherical mirrors, the foci of said ellipsoidal mirror and the center of said aperture stop means are substantially coincident with said optical axis, whereby said light beams pass through the system unobscured by any of said mirror segments; and light detector means being positioned in front of the concave spherical reflecting surface of said tertiary mirror means at the location of said planar focal surface and clear of light being received by said tertiary mirror means from said secondary mirror means.
Claim 3
Dependent Claim
34 words
The system as defined by claim 1 wherein said aperture stop means is located at the light beam waist region of light beams traversing from said secondary mirror means to said tertiary mirror means.
Claim 4
Dependent Claim
19 words
The system as defined by claim 2 wherein said aperture stop means comprises an adjustable iris type of diaphragm.
Claim 5
Dependent Claim
23 words
The system as defined by claim 1 wherein said baffle means comprises an elongated inwardly converging baffle having a generally rectangular cross section.
Claim 6
Dependent Claim
41 words
The system as defined by claim 4 wherein said baffle includes means for limiting the field of view to at least 20° in a first direction and at least 30° in a second mutually orthogonal direction relative to the first direction.
Claim 7
Dependent Claim
33 words
The system as defined by claim 5 wherein said first direction comprises a height or Y axis direction and said second direction comprises a width or X axis direction of said imaging system.
Claim 8
Dependent Claim
16 words
The system as defined by claim 4 wherein said baffle additionally includes interiorally located anti-reflective means.
Claim 9
Dependent Claim
31 words
The system as defined by claim 1 and additionally including a housing for supporting said baffle means and containing all said mirror means, said aperture stop means, and said detector means.
Claim 10
Dependent Claim
14 words
The system as defined by claim 8 wherein said housing comprises a light-tight housing.
Claim 11
Dependent Claim
21 words
The system as defined by claim 1 wherein said detector means includes a planar detector element at said planar focal surface.
Claim 12
Dependent Claim
15 words
The system as defined by claim 10 wherein said planar detector comprises a photoelectronic device.
Claim 13
Dependent Claim
18 words
The system as defined by claim 10 wherein said planar detector element comprises a television type imaging device.
Claim 14
Dependent Claim
37 words
The system as defined by claim 10 wherein said planar detector is selectively responsive to light beams over a portion of the electromagnetic spectrum ranging between the far ultraviolet and infrared regions thereof, including the visible region.
Claim 15
Dependent Claim
21 words
The system as defined by claim 13 and additionally including optical filter means located in the path of said light beams.
Claim 16
Dependent Claim
29 words
The system as defined by claim 13 and additionally including optical filter means positioned in front of said planar detector between said detector means and said tertiary mirror means.
Claim 17
Dependent Claim
29 words
The system as defined by claim 13 and additionally including optical filter means positioned behind said aperture stop means between said aperture stop means and said tertiary mirror means.
Claim 18
Dependent Claim
14 words
The system as defined by claim 1 wherein said detector means comprises photographic film.
References Cited (Backward Citations)
US3432219A
Cited
US3811749A
Cited
US3963328A
Cited
SU478546A1
Cited
US3907401A
Cited
US4101195A
Cited
US4265510A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-07-07 | 1990-01-06 | 1990-07-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-07-07 | 1994-01-06 | 1994-07-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-07-07 | 1998-01-06 | 1998-07-08 | $7700.00 | Window Closed / Lapsed |