US4073574A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical projector
Assignee: US Philips Corp
•
Filing: 1976-10-01
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Granted: 1978-02-14
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Expires: 1996-10-01
Abstract
Abstract An aspheric element, placed near a principle plane of an wide-angle, wide-aperture image forming system and having in its aspheric function a term proportional to the third power of the distance from the optic axis improves off-axis revolution.
Inventors
- 👤 John A. Clarke
- 👤 Harry Howden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:27
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/18; G02B13/00; G02B13/18
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
49 words
An optical system comprising an image forming system and a symmetrical aspheric element placed proximate a principal plane of the image forming system, the thickness of the aspheric element having an aspheric polynomial function including a term proportional to the third power of the distance from the optic axis.
Claim 2
Dependent Claim
49 words
An optical system comprising an image forming system and a symmetrical aspheric element placed proximate a principal plane of the image forming system, the thickness of the aspheric element having an aspheric polynomial function including a term proportional to the third power of the distance from the optic axis.
Claim 3
Dependent Claim
33 words
An optical system as claimed in claim 1 wherein a further term is included in the aspheric function of the aspheric element, which is proportional to another odd power of the said distance.
Claim 4
Dependent Claim
31 words
An optical system as claimed in claim 1 wherein a single term proportional to the fifth power of the said distance is included in the aspheric function of the aspheric element.
Claim 5
Dependent Claim
42 words
An optical system as claimed in claim 3 wherein the terms defining the aspheric function of the aspheric element are limited only to a term proportional to the third power and a term proportional to the fifth power of the said distance.
Claim 6
Dependent Claim
36 words
An optical system as claimed in claim 1 wherein the image forming system comprises a spherical reflecting mirror for forming said image and a refractive element opposite said mirror for correcting spherical aberrations of said mirror.
Claim 7
Dependent Claim
17 words
An optical system as claimed in claim 5 wherein the refractive correcting element is a Schmidt plate.
Claim 8
Dependent Claim
24 words
An optical system as claimed in claim 6 wherein a limiting aperture is placed at the mirror and is adapted to provide off-axis vignetting.
References Cited (Backward Citations)
US2298808A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-02-13 | 1981-08-15 | 1982-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-13 | 1985-08-15 | 1986-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-13 | 1989-08-15 | 1990-02-14 | $7700.00 | Window Closed / Lapsed |