US3748020A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Catadioptric optical system having multilayer filter reflector
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1972-03-31
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Granted: 1973-07-24
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Expires: 1992-03-31
Abstract
Abstract A catadioptric optical system for improving the quality of the image and the transmittance of the optical system. The invention is an improvement on the Cassegrain and Newtonian optical systems or any other optical systems wherein the secondary mirror partially obscures the primary mirror. The secondary mirror in these optical systems is provided with a multilayer, angle sensitive, filter coating, with the coating being designed to pass to the primary mirror substantially all radiation received along the optical axis and to reflect substantially all radiation received at angles of incidence other than along said optical axis. With this arrangement radiation normally blocked by the secondary mirror is passed to the primary mirror which results in an effective increase in the transmittance of the optical system and an improved modulation transfer function for the optical system.
Inventors
- 👤 G Wirtenson
- 👤 R Fischer
- 👤 W Knapp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:41
CPC Classifications
G; G02; G02B; G02B17/00; G02B17/02; G02B17/06; G02B17/0605; G02B17/061
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
196 words
A Catadioptric telescope for improving the quality of the image produced by the telescope and comprising: a. a primary mirror placed along the optical axis of the optical system for gathering radiation; b. a secondary mirror for reflecting to an image plane radiation reflected by said primary mirror onto the secondary mirror; c. said secondary mirror being positioned at a given angle relative to the optical axis of the optical system and thereby being positioned at said given angle relative to incoming radiation along the optical axis; d. said secondary mirror having an angle sensitive multilayer filter coating thereon, said angle sensitive filter coating passing substantially all radiation incident thereon at said given angle and reflecting substantially all radiation incident thereon at angles other than said given angle whereby radiation normally blocked by said secondary mirror will be passed through said secondary mirror to said primary mirror and be reflected by said primary mirror back to said secondary mirror for further reflection to said image plane, thereby increasing the effective transmittance of the optical system for a given diameter and focal length of the primary mirror and improving the modulation transfer function of the optical system.
Claim 2
Dependent Claim
196 words
A Catadioptric telescope for improving the quality of the image produced by the telescope and comprising: a. a primary mirror placed along the optical axis of the optical system for gathering radiation; b. a secondary mirror for reflecting to an image plane radiation reflected by said primary mirror onto the secondary mirror; c. said secondary mirror being positioned at a given angle relative to the optical axis of the optical system and thereby being positioned at said given angle relative to incoming radiation along the optical axis; d. said secondary mirror having an angle sensitive multilayer filter coating thereon, said angle sensitive filter coating passing substantially all radiation incident thereon at said given angle and reflecting substantially all radiation incident thereon at angles other than said given angle whereby radiation normally blocked by said secondary mirror will be passed through said secondary mirror to said primary mirror and be reflected by said primary mirror back to said secondary mirror for further reflection to said image plane, thereby increasing the effective transmittance of the optical system for a given diameter and focal length of the primary mirror and improving the modulation transfer function of the optical system.
Claim 3
Dependent Claim
23 words
Apparatus as set forth in claim 1 wherein said optical system is a Cassegrain optical system wherein said given angle is approximately 90*.
Claim 4
Dependent Claim
16 words
Apparatus as set forth in claim 1 wherein said optical system is a Newtonian optical system.
Claim 5
Dependent Claim
14 words
Apparatus as set forth in claim 3 wherein said given angle is approximately 45*.
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) | 1976-07-23 | 1977-01-22 | 1977-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-23 | 1981-01-22 | 1981-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-23 | 1985-01-22 | 1985-07-24 | $7700.00 | Window Closed / Lapsed |