US4998801A
Expired / Lapsed
US
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Optical low-pass filter and photographic system using the same
Assignee: Canon Inc
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Filing: 1989-07-13
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Granted: 1991-03-12
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Expires: 2009-07-13
Abstract
Abstract An optical low-pass filter formed in a trapezoid wave profile having the top and bottom sides of lengths "a" and "b" respectively, a height "δ" thereof and a length of one period thereof and made from a material having a refractive index "n", and satisfying the following conditions: for a wavelength of λ M ≧1.6 λm, ##EQU1## wherein λ M and λm are respectively maximum and minimum wavelengths in a wavelength range in which the filter works, and MIN(x,y) represents the smaller one of values which variables x and y take.
Inventors
- 👤 Akihiko Shiraishi
- 👤 Kazuo Fujibayashi
- 👤 Masatake Kato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 08:57
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/42; G02B27/46
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
114 words
An optical low-pass filter, satisfying the following conditions: a profile of said filter being of a trapezoid wave form, and for a wavelength range of λ M ≦1.6 λm, ##EQU20## wherein "a" is a width of a flat portion of a top side of said trapezoid wave form, "b" is a width of a flat portion of a bottom side thereof, "δ" is a height thereof, "d" is a length of one period thereof, "n" is a refractive index of a material of said filter, λ M and λm are maximum and minimum wavelengths in a predetermined wavelength range respectively, and MIN(x,y) represents the smaller one of values which variables x and y take.
Claim 2
Dependent Claim
114 words
An optical low-pass filter, satisfying the following conditions: a profile of said filter being of a trapezoid wave form, and for a wavelength range of λ M ≦1.6 λm, ##EQU20## wherein "a" is a width of a flat portion of a top side of said trapezoid wave form, "b" is a width of a flat portion of a bottom side thereof, "δ" is a height thereof, "d" is a length of one period thereof, "n" is a refractive index of a material of said filter, λ M and λm are maximum and minimum wavelengths in a predetermined wavelength range respectively, and MIN(x,y) represents the smaller one of values which variables x and y take.
Claim 3
Dependent Claim
91 words
An optical low-pass filter, satisfying the following conditions: a profile of said filter being of a trapezoid wave form, and for a wavelength range of λ M ≦1.6 λm, 0.2≦a/d≦0.3 0.2≦b/d≦0.3 ##EQU21## wherein "a" is a width of a flat portion of a top side of said trapezoid wave form, "b" is a width of a flat portion of a bottom side thereof, "δ" is a height thereof, "d" is a length of one period thereof, and λ.sub.M and λm are maximum and minimum wavelengths in a predetermined wavelength range respectively.
Claim 4
Dependent Claim
91 words
An optical low-pass filter, satisfying the following conditions: a profile of said filter being of a trapezoid wave form, and for a wavelength range of λ M ≦1.6 λm, 0.2≦a/d≦0.3 0.2≦b/d≦0.3 ##EQU21## wherein "a" is a width of a flat portion of a top side of said trapezoid wave form, "b" is a width of a flat portion of a bottom side thereof, "δ" is a height thereof, "d" is a length of one period thereof, and λ.sub.M and λm are maximum and minimum wavelengths in a predetermined wavelength range respectively.
Claim 5
Dependent Claim
164 words
A photographic system comprising: an objective lens assembly having a plurality of lens units; a solid state image pickup element receptive of an image of an object produced by said objective lens assembly for forming video signals; and an optical low-pass filter arranged in a space between adjacent two of said lens units, and satisfying the following conditions: a profile of said filter being of a trapezoid wave form, and for a wavelength range of λ M ≦1.6 λm, ##EQU22## wherein "a" is a width of a flat portion of a top side of said trapezoid wave form, "b" is a width of a flat portion of a bottom side thereof, "δ" is a height thereof, "d" is a length of one period thereof, "n" is a refractive index of a material of said filter, λ M and λm are maximum and minimum wavelengths in a predetermined wavelength range respectively, and MIN(x,y) represents the smaller one of values which variables x and y take.
Claim 6
Dependent Claim
164 words
A photographic system comprising: an objective lens assembly having a plurality of lens units; a solid state image pickup element receptive of an image of an object produced by said objective lens assembly for forming video signals; and an optical low-pass filter arranged in a space between adjacent two of said lens units, and satisfying the following conditions: a profile of said filter being of a trapezoid wave form, and for a wavelength range of λ M ≦1.6 λm, ##EQU22## wherein "a" is a width of a flat portion of a top side of said trapezoid wave form, "b" is a width of a flat portion of a bottom side thereof, "δ" is a height thereof, "d" is a length of one period thereof, "n" is a refractive index of a material of said filter, λ M and λm are maximum and minimum wavelengths in a predetermined wavelength range respectively, and MIN(x,y) represents the smaller one of values which variables x and y take.
Claim 7
Dependent Claim
78 words
A photographic system comprising: an objective lens assembly having a plurality of lens units; a solid state image pickup element receptive of an image of an object by said objective lens assembly for forming video signals; and an optical low-pass filter arranged in a space between adjacent two of said lens units, and satisfying the following conditions: a profile of said filter being of a trapezoid wave form, and for a wavelength range of λ M ≦1.6 λm,
Claim 8
Dependent Claim
78 words
A photographic system comprising: an objective lens assembly having a plurality of lens units; a solid state image pickup element receptive of an image of an object by said objective lens assembly for forming video signals; and an optical low-pass filter arranged in a space between adjacent two of said lens units, and satisfying the following conditions: a profile of said filter being of a trapezoid wave form, and for a wavelength range of λ M ≦1.6 λm,
Claim 9
Dependent Claim
62 words
2≦a/d≦0.3 0.2≦b/d≦0.3 ##EQU23## wherein "a" is a width of a flat portion of a top side of said trapezoid wave form, "b" is a width of a flat portion of a bottom side thereof, "δ" is a height thereof, "d" is a length of one period thereof, and λ.sub.M and λm are maximum and minimum wavelengths in a predetermined wavelength range respectively.
Claim 10
Dependent Claim
62 words
2≦a/d≦0.3 0.2≦b/d≦0.3 ##EQU23## wherein "a" is a width of a flat portion of a top side of said trapezoid wave form, "b" is a width of a flat portion of a bottom side thereof, "δ" is a height thereof, "d" is a length of one period thereof, and λ.sub.M and λm are maximum and minimum wavelengths in a predetermined wavelength range respectively.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-03-11 | 1994-09-10 | 1995-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-03-11 | 1998-09-10 | 1999-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-03-11 | 2002-09-10 | 2003-03-12 | $7700.00 | Window Closed / Lapsed |