US4085319A
Expired / Lapsed
US
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Spatial-multiplex, spatial-diversity optical communication scheme
Assignee: United States Department of the Army
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Filing: 1977-02-01
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Granted: 1978-04-18
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Expires: 1997-02-01
Abstract
Abstract An optical communications system for coding, transmitting, receiving, and coding digital message signals is described. A beam from a coherent optical source, such as a laser, is transmitted through an aperture in which there is disposed a random phase screen, e.g., ground glass. One or more isometric bar gratings containing the coded message data in a particular amplitude distribution pattern are disposed adjacent to the ground glass in the optical transmission path. The ground glass, phase screen, introduces a random coding to the message bit. At the receiver a plurality of point detectors sense the signals to facilitate subsequent decoding of the message.
Inventors
- 👤 Paul H. Deitz
- 👤 Gary L. Durfee
- 👤 Stephen S. Wolff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:23
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/11; H04B10/112; H04B10/1121
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
110 words
An optical communication system for transmitting coded message bits comprising: a source of coherent radiation for transmitting a beam of light along an optical path; means for spatially phase modulating said beam of light; coding means in said optical path for modulating said beam of light to generate a selected spatial amplitude pattern through a cross section of said beam, the code corresponding to said selected spatial amplitude pattern and forming a message bit therein; means for detecting the amplitude of said pattern in at least two positions separated by a predetermined distance through the cross section of said beam to determine the presence or absence of said message bit.
Claim 2
Dependent Claim
110 words
An optical communication system for transmitting coded message bits comprising: a source of coherent radiation for transmitting a beam of light along an optical path; means for spatially phase modulating said beam of light; coding means in said optical path for modulating said beam of light to generate a selected spatial amplitude pattern through a cross section of said beam, the code corresponding to said selected spatial amplitude pattern and forming a message bit therein; means for detecting the amplitude of said pattern in at least two positions separated by a predetermined distance through the cross section of said beam to determine the presence or absence of said message bit.
Claim 3
Dependent Claim
42 words
The optical communication system according to claim 1 wherein said means for spatially phase modulating said beam of light comprises a section of ground glass disposed within a beam defining aperture, said ground glass being rotated in the plane of said aperture.
Claim 4
Dependent Claim
35 words
The optical communication system according to claim 1 wherein said coding means comprises an isometric bar grating having a predetermined number of lines per inch and at a predetermined angular orientation within the beam path.
Claim 5
Dependent Claim
27 words
The optical communication system according to claim 3 wherein said coding means comprises a plurality of said isometric bar gratings disposed in tandem in said beam path.
Claim 6
Dependent Claim
25 words
The optical communication system of claim 3 wherein said bar grating is disposed closely adjacent to said means for spatially modulating said beam of light.
Claim 7
Dependent Claim
39 words
The optical communication system according to claim 1 wherein there is further provided rotatable mirror means for performing a line scan through the cross section of said light beam and for directing the scanned light to said detecting means.
Claim 8
Dependent Claim
45 words
The optical communication system of claim 1 wherein said detecting means comprises at least two point detectors spaced by a predetermined distance, said distance corresponding to the far field spatial lag for the fundamental spatial frequency of the bar grating containing the code being transmitted.
Claim 9
Dependent Claim
27 words
The optical communication system of claim 7 wherein means are provided to compute a time averaged correlation of the outputs of said at least two point detectors.
Claim 10
Dependent Claim
31 words
The optical system of claim 8 wherein said means for computing comprises integrator means for integrating the product of the output of said two point detectors over a predetermined time interval.
Claim 11
Dependent Claim
16 words
The optical system according to claim 1 wherein said source of coherent radiation is a laser.
References Cited (Backward Citations)
US3755676A
Cited
US3987428A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-04-17 | 1981-10-17 | 1982-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-04-17 | 1985-10-17 | 1986-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-04-17 | 1989-10-17 | 1990-04-18 | $7700.00 | Window Closed / Lapsed |