US4255019A
Expired / Lapsed
US
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Diffractive color filter
Assignee: RCA Corp
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Filing: 1979-04-09
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Granted: 1981-03-10
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Expires: 1999-04-09
Abstract
Abstract A diffractive color filter, comprised of proximately disposed diffraction grating and lenticular lens structures, which may be embossed on plastic sheet, cooperates with an imaging lens to produce color stripes or color spots of an image on a photosensitive surface. The diffractive color filter may be used, for example, as a color-encoding stripe filter of a color TV camera.
Inventors
- 👤 Karl H. Knop
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:04
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/20; G02B27/00; G02B27/42; G02B27/4288; G02B27/4205; G02B5/28
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
137 words
A diffractive color filter for use in a polychromatic-light imaging system including an imaging lens and a photosensitive surface situated in an image plane of said lens, said lens having an f-number F c equal or greater than a minimum f-number F c min ; said filter comprising: a lenticular lens array having a lens periodicity L, a focal length f and an effective f-number F L proportional to f/L, said array being adapted to be situated with its focal plane substantially in coincidence with said photosensitive surface, a diffractive structure situated substantially in proximity to said array, said diffractive structure including a phase grating having a predetermined grating profile S(x) and grating line spacing d, where d is larger than a certain wavelength γ of said polychromatic light, and wherein the following relationship exists: F.sub.c.sup.min ≧d/γ
Claim 2
Dependent Claim
137 words
A diffractive color filter for use in a polychromatic-light imaging system including an imaging lens and a photosensitive surface situated in an image plane of said lens, said lens having an f-number F c equal or greater than a minimum f-number F c min ; said filter comprising: a lenticular lens array having a lens periodicity L, a focal length f and an effective f-number F L proportional to f/L, said array being adapted to be situated with its focal plane substantially in coincidence with said photosensitive surface, a diffractive structure situated substantially in proximity to said array, said diffractive structure including a phase grating having a predetermined grating profile S(x) and grating line spacing d, where d is larger than a certain wavelength γ of said polychromatic light, and wherein the following relationship exists: F.sub.c.sup.min ≧d/γ
Claim 3
Dependent Claim
85 words
The diffractive subtractive filter defined in claim 1 wherein said lenticular lens array is composed of a material exhibiting an index of refraction n 1 , said array material extending to said focal plane of said array, thereby to provide an f-number F L for said array equal to f/n 1 L, wherein said diffractive structure is composed of a material exhibiting an index of refraction n 2 , and wherein the following further relationship exists: F.sub.L =d/Kγ where K is a particular plural integer.
Claim 4
Dependent Claim
26 words
The diffractive color filter defined in claim 2, wherein said grating profile S(x) has a certain rectangular wave form of depth a' and aspect ratio b.
Claim 5
Dependent Claim
34 words
The diffractive color filter defined in claim 3, wherein said line spacing d is at least five micrometers and said aspect ratio is substantially one-half, whereby said certain rectangular waveform is a square waveform.
Claim 6
Dependent Claim
29 words
The diffractive color filter defined in claim 3, wherein said line spacing d is substantially less than five micrometers and said aspect ratio b is substantially less than one-half.
Claim 7
Dependent Claim
29 words
The diffractive color filter defined in claim 5, wherein said aspect ratio b has that value which produces substantially saturated color hues in said focal plane of said array.
Claim 8
Dependent Claim
32 words
The diffractive color filter defined in claim 3, wherein d is no greater than 1.5 micrometers, γ is approximately 0.5 micrometers, K is equal to two and n 1 is about 1.5.
Claim 9
Dependent Claim
42 words
The diffractive color filter defined in claim 3, wherein d is substantially 1.4 micrometers, L is in the range of 30-50 micrometers, K is equal to two, both n 1 and n 2 equal 1.54, and said polychromatic light is white light.
Claim 10
Dependent Claim
48 words
The diffractive color filter defined in claim 2, wherein said array is a linear array of cylindrical lenses and wherein said diffractive structure includes a single grating having lines oriented substantially parallel to the axis of said cylindrical lenses, whereby said color filter is a stripe color filter.
Claim 11
Dependent Claim
25 words
The diffractive color filter defined in claim 2, wherein said array is a two-dimensional array, and wherein said diffractive structure comprises two angularly-displaced phase gratings.
Claim 12
Dependent Claim
36 words
The diffractive color filter defined in claim 10, wherein said two-dimensional array is a rectangular array, and wherein said two angularly-displaced phase gratings are oriented at a substantially ninety degree angle with respect to each other.
Claim 13
Dependent Claim
36 words
The diffractive color filter defined in claim 10, wherein said two-dimensional array is a hexagonal array and wherein said two angularly-displaced phase gratings are oriented at a substantially one-hundred-twenty degree angle with respect to each other.
Claim 14
Dependent Claim
21 words
The diffractive color filter defined in claim 2, wherein said array and said diffractive structure are comprised of embossed plastic material.
References Cited (Backward Citations)
US2733291A
Cited
US3264164A
Cited
US3582984A
Cited
US3834785A
Cited
US3940788A
Cited
US3957354A
Cited
US4079411A
Cited
US4130347A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-03-09 | 1984-09-08 | 1985-03-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-09 | 1988-09-08 | 1989-03-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-09 | 1992-09-08 | 1993-03-10 | $7700.00 | Window Closed / Lapsed |