US3681519A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Single-tube color cameras with optical spatial frequency filters
Assignee: AT&T Inc
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Filing: 1970-12-21
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Granted: 1972-08-01
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Expires: 1990-12-21
Abstract
Abstract In a Kell-type single-tube color camera system, an optical spatial frequency filter in the form of an asymmetrical rectangular wave phase-only diffraction grating is disposed between the object scene and the striped color filters. The optical filter is designed to provide an optical transfer function that has a region of high attenuation which extends from the lower limit of the carrier frequency passband, produced by the modulation of the imaged input scene by the striped color filters, to at least the upper limit of said passband.
Inventors
- 👤 Arthur Bertel Larsen
- 👤 Thomas Patrick Sosnowski
- 👤 Richard Lee Townsend Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 00:20
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/42; G02B27/46; H; H04; H04N; H04N23/00; H04N23/10; H04N23/12
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
127 words
A single-tube color camera system comprising an image scanning device, striped color filter means disposed in the input light path of said image scanning device and serving to spatially modulate at least two of three selected primary color images, and a lossless optical spatial frequency filter in the form of a phase-only diffraction grating having alternate and parallel stripes of the same transmissivity and a predetermined amount of relative phase retardation between alternate stripes, said optical spatial frequency filter being disposed at a given position between a scene and said color filter means and having a composite optical transfer function with a region of high attenuation that extends at least over the frequency passband produced by the modulation of the input scene by said color filter means.
Claim 2
Dependent Claim
127 words
A single-tube color camera system comprising an image scanning device, striped color filter means disposed in the input light path of said image scanning device and serving to spatially modulate at least two of three selected primary color images, and a lossless optical spatial frequency filter in the form of a phase-only diffraction grating having alternate and parallel stripes of the same transmissivity and a predetermined amount of relative phase retardation between alternate stripes, said optical spatial frequency filter being disposed at a given position between a scene and said color filter means and having a composite optical transfer function with a region of high attenuation that extends at least over the frequency passband produced by the modulation of the input scene by said color filter means.
Claim 3
Dependent Claim
45 words
A color camera system as defined in claim 1 wherein the three primary colors are red, green and blue, said optical filter providing for both red and blue light an optical transfer function that has a constant null region which extends over said frequency passband.
Claim 4
Dependent Claim
26 words
A color camera system as defined in claim 2 wherein said stripes are orthogonally disposed with respect to the scan lines of the image scanning device.
Claim 5
Dependent Claim
47 words
A color camera system as defined in claim 3 wherein said diffraction grating comprises an asymmetrical rectangular wave phase grating having a grating duty cycle (a/ Lambda ) equal to 0.26 and a relative phase retardation ( phi o) between alternate stripes equal to 1.15 pi .
Claim 6
Dependent Claim
30 words
A color camera system as defined in claim 4 wherein said phase grating is established by a developed layer of dichromated gelatin deposited on an object lens of the system.
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) | 1975-08-01 | 1976-01-31 | 1976-08-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-01 | 1980-01-31 | 1980-08-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-01 | 1984-01-31 | 1984-08-01 | $7700.00 | Window Closed / Lapsed |