Patent US4772107A successfully refreshed from Google Patents.
US4772107A
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Wide angle lens with improved flat field characteristics
Assignee: SVG LITHOGRAPHY Inc A CORP OF
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Filing: 1986-11-05
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Granted: 1988-09-20
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Expires: 2006-11-05
Abstract
Abstract There is disclosed an improvement in wide angle lenses wherein very flat field characteristics are achieved. This is accomplished by a novel two element field flattener just before the image plane. One of the elements is positive and the other negative. It is possible to thereby correct both third and fifth order Petzval curvature, as well as third and fifth order distortion.
Inventors
- 👤 Irwin Friedman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 09:11
CPC Classifications
G; G02; G02B; G02B3/00; G02B13/00; G02B13/04; G02B27/00; G02B27/0025
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
66 words
In a lens assembly including a field flattener as the last element before the image plane, the improvement wherein said field flattener comprises: a strong negative first element having surfaces which over correct the third order Petzval curvature; and a strong positive second element disposed between said first element and the image plane having surfaces which substantially offset the over correction introduced by the first element.
Claim 2
Dependent Claim
66 words
In a lens assembly including a field flattener as the last element before the image plane, the improvement wherein said field flattener comprises: a strong negative first element having surfaces which over correct the third order Petzval curvature; and a strong positive second element disposed between said first element and the image plane having surfaces which substantially offset the over correction introduced by the first element.
Claim 3
Dependent Claim
15 words
The improvement of claim 1 wherein said second element substantially corrects fifth order Petzval curvature.
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) | 1991-09-20 | 1992-03-21 | 1992-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-20 | 1996-03-21 | 1996-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-20 | 2000-03-21 | 2000-09-20 | $7700.00 | Window Closed / Lapsed |