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US4804249A
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Optical filter for incoherent imaging systems
Assignee: Honeywell Inc
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Filing: 1986-12-24
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Granted: 1989-02-14
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Expires: 2006-12-24
Abstract
Abstract An optical filter for use with an imaging lens in an incoherent imaging system operating in broadband illumination for increasing the depth-of-focus of the lens while maintaining energy thru-put is disclosed. The optical filter comprises a transparent support having on one surface thereof an array of transparent, discrete steps of substantially equal size, each step having a thickness that differs from all other steps by at least the coherence length of the radiation to be passed and the size of the array being equal to the size of the lens. In use, the optical filter is positioned in front of the imaging lens. When so positioned, the depth of focus of the imaging lens is proportional to the size of the individual steps rather than the size of the lens while the energy thru-put of the imaging remains the same as it would be without the optical filter.
Inventors
- 👤 George O. Reynolds
- 👤 Peter F. Mueller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:25
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/42; G02B27/46; G02B27/0025
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
69 words
An optical filter for increasing the depth-of-focus of an imaging lens operating in an incoherent imaging system while maintaining energy thru-put, said optical filter comprising a transparent support having on one surface thereof an array of discrete transparent steps of substantially equal cross-sectional area, each step having a thickness that differs from all other steps by at least the coherence length of the radiation transmitted through the imaging lens.
Claim 2
Dependent Claim
69 words
An optical filter for increasing the depth-of-focus of an imaging lens operating in an incoherent imaging system while maintaining energy thru-put, said optical filter comprising a transparent support having on one surface thereof an array of discrete transparent steps of substantially equal cross-sectional area, each step having a thickness that differs from all other steps by at least the coherence length of the radiation transmitted through the imaging lens.
Claim 3
Dependent Claim
24 words
The optical filter of claim 1 and wherein the overall area of the array is about equal to the area of the imaging lens.
Claim 4
Dependent Claim
39 words
The optical filter of claim 2 and wherein the area of a step is equal to the area of an aperture which if positioned in front of the imaging lens would provide a desired depth-of-focus for said imaging lens.
Claim 5
Dependent Claim
72 words
An incoherent imaging system comprising: a. a lens, and b. an optical filter in front of the lens for increasing the depth-of-focus of the lens, said optical filter comprising a transparent support having on one surface thereof an array of discrete transparent steps of equal cross-sectional area, each step having a thickness that differs from all other steps by at least the coherence length of the radiation transmitted through the imaging lens.
Claim 6
Dependent Claim
72 words
An incoherent imaging system comprising: a. a lens, and b. an optical filter in front of the lens for increasing the depth-of-focus of the lens, said optical filter comprising a transparent support having on one surface thereof an array of discrete transparent steps of equal cross-sectional area, each step having a thickness that differs from all other steps by at least the coherence length of the radiation transmitted through the imaging lens.
Claim 7
Dependent Claim
68 words
An optical filter for bandlimiting the spatial frequency of an imaging lens operating with incoherent radiation while maintaining energy thru-put, said optical filter comprising a transparent support having on one surface thereof an array of discrete transparent steps of substantially equal cross-sectional area, each step having a thickness that differs from all other steps by at least the coherence length of the radiation transmitted through the imaging lens.
Claim 8
Dependent Claim
68 words
An optical filter for bandlimiting the spatial frequency of an imaging lens operating with incoherent radiation while maintaining energy thru-put, said optical filter comprising a transparent support having on one surface thereof an array of discrete transparent steps of substantially equal cross-sectional area, each step having a thickness that differs from all other steps by at least the coherence length of the radiation transmitted through the imaging lens.
References Cited (Backward Citations)
US2959105A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-02-14 | 1992-08-15 | 1993-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-14 | 1996-08-15 | 1997-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-14 | 2000-08-15 | 2001-02-14 | $7700.00 | Window Closed / Lapsed |