US3643097A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical filter for suppressing noise which utilizes a graded optical fiber and means for controlling transverse position of iris
Assignee: NEC Corp
•
Filing: 1969-11-12
•
Granted: 1972-02-15
•
Expires: 1989-11-12
Abstract
Abstract A noise suppression optical filter having practical utility in increasing the signal-to-noise ratio of a laser communication system. The filter comprises a converging light guide element having an index of refraction which varies inversely with the square of the distance from the central axis. Irises having apertures of specified diameters are located at the input and output ends of that light guide, and means are provided to position these apertures in alignment with the light travelling through the guide.
Inventors
- 👤 Atsufumi Ueki
- 👤 Ryuji Tatsumi
- 👤 Nippon Selfoc Ltd
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 10:52
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/25; H04B10/2507
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
158 words
A noise suppression optical filter for operation on a light beam having a wavelength lambda o in vacuum comprising a converging light guide having a refractive index given by the expression n no(1- 1/2 ar2), where no is the refractive index on the axis of said light guide, a is a positive converging coefficient specific to said light guide, and r is a radial distance from the axis, and a length l given by the expression a first iris disposed at the input end of said light guide and having a circular aperture at its center part, the diameter of said aperture being two to four times as great as the value and a second iris formed of light-absorptive material and disposed at the output end of said light guide means and having a circular aperture at its center, the diameter of the aperture of said second iris being two to four times as great as the value
Claim 2
Dependent Claim
158 words
A noise suppression optical filter for operation on a light beam having a wavelength lambda o in vacuum comprising a converging light guide having a refractive index given by the expression n no(1- 1/2 ar2), where no is the refractive index on the axis of said light guide, a is a positive converging coefficient specific to said light guide, and r is a radial distance from the axis, and a length l given by the expression a first iris disposed at the input end of said light guide and having a circular aperture at its center part, the diameter of said aperture being two to four times as great as the value and a second iris formed of light-absorptive material and disposed at the output end of said light guide means and having a circular aperture at its center, the diameter of the aperture of said second iris being two to four times as great as the value
Claim 3
Dependent Claim
80 words
The noise suppression optical filter of claim 1 further comprising light-detecting means composed of a plurality of separate partial detectors disposed on the surface of one of said irises on the side facing the incoming light sources, and means connected to said detectors for transversely moving said one of said irises in response to the output of said light-detecting means to align the center of the aperture of said iris with the light beam travelling through said light guide means.
Claim 4
Dependent Claim
47 words
The noise suppression optical filter of claim 2, in which the other of said irises comprises second separate partial detectors, and further comprising second moving means connected to the other of said irises for transversely moving the latter in response to the output of said second detectors.
Claim 5
Dependent Claim
114 words
A noise suppression optical filter comprising a converging light guide element having input and output ends and a length l given by the expression where a is the converging coefficient specific to said light guide element, a first iris disposed at said input, a second iris disposed at said output end, each of said irises having a central aperture, at least one of said irises comprising a plurality of separate light detectors on the light incident surface thereof, and means connected to said iris and responsive to the relative outputs of said light detectors to align the aperture of said one of said irises with the light beam travelling through said light guide element.
Claim 6
Dependent Claim
114 words
A noise suppression optical filter comprising a converging light guide element having input and output ends and a length l given by the expression where a is the converging coefficient specific to said light guide element, a first iris disposed at said input, a second iris disposed at said output end, each of said irises having a central aperture, at least one of said irises comprising a plurality of separate light detectors on the light incident surface thereof, and means connected to said iris and responsive to the relative outputs of said light detectors to align the aperture of said one of said irises with the light beam travelling through said light guide element.
Claim 7
Dependent Claim
46 words
The noise suppression optical filter of claim 4, in which the other of said irises comprises second separate detectors, and further comprising second moving means connected to the other of said irises for transversely moving the latter in response to the output of said second detectors.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-14 | 1975-08-16 | 1976-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-14 | 1979-08-16 | 1980-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-14 | 1983-08-16 | 1984-02-15 | $7700.00 | Window Closed / Lapsed |