US3863064A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Differential retrocommunicator
Assignee: Lanteris Space LLC
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Filing: 1972-01-03
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Granted: 1975-01-28
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Expires: 1992-01-03
Abstract
Abstract An optical communications terminal employs two retrodirective reflective elements, one of which is modulated along the optical beam axis. The unmodulated return beam provides a reference for comparison with the modulated beam to enable heterodyne demodulation. If the primary source is a dual-polarization laser having a controlled frequency offset between the orthogonally polarized outputs, polarizing optics can be employed at the terminal to separate the primary beams. Each beam can be applied to a separate retroreflector so that one reflected beam is modulated with respect to the other. The two beams are returned back to the source where they can be heterodyned in a photodetector and demodulated using conventional FM or PM receiver techniques. This provides a communications system having a passive terminal and a high degree of immunity to noise and path turbulence interference.
Inventors
- 👤 Walter M Doyle
- 👤 Matthew B White
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:25
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/25; H04B10/2587; G; G01; G01S; G01S17/00; G01S17/74; G02; G02F; G02F2/00; G02F2/002
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
124 words
An improved remote terminal intended for use in an optical retrocommunications system, said system having, in addition to said remote terminal, a base terminal comprising an optical transmitter and an optical receiver, said transmitter emitting optical energy directed at said remote terminal and said optical receiver receiving optical energy reflected from said remote terminal to recover information impressed on said optical energy at said remote terminal, wherein said improvement comprises: a. two retrodirective reflectors, each capable of receiving a portion of said emitted optical energy from said optical transmitter and returning a portion of said emitted optical energy to said receiver, and b. means for phase modulating the reflection of one of said reflectors relative to the reflection of the other of said reflectors.
Claim 2
Dependent Claim
124 words
An improved remote terminal intended for use in an optical retrocommunications system, said system having, in addition to said remote terminal, a base terminal comprising an optical transmitter and an optical receiver, said transmitter emitting optical energy directed at said remote terminal and said optical receiver receiving optical energy reflected from said remote terminal to recover information impressed on said optical energy at said remote terminal, wherein said improvement comprises: a. two retrodirective reflectors, each capable of receiving a portion of said emitted optical energy from said optical transmitter and returning a portion of said emitted optical energy to said receiver, and b. means for phase modulating the reflection of one of said reflectors relative to the reflection of the other of said reflectors.
Claim 3
Dependent Claim
13 words
The improvement of claim 1 wherein said two retrodirective reflectors are modulated differentially.
Claim 4
Dependent Claim
32 words
The improvement of claim 1 wherein said reflectors comprise corner cubes and said means for modulating includes means for moving at least one reflector in a direction parallel to the optical path.
Claim 5
Dependent Claim
32 words
The improvement of claim 1 wherein said reflectors comprise cats eyes and said means for modulating includes means for moving at least one reflector in a direction parallel to the optical path.
Claim 6
Dependent Claim
16 words
The improvement of claim 1 wherein said means for modulating comprise at least one electro-optical crystal.
Claim 7
Dependent Claim
67 words
The system of claim 1 wherein said transmitter is further characterized as being of the dual-polarization laser type, said dual polarization laser having two orthogonally polarized outputs, said two retrodirective reflectors include further means for making each reflector responsive to a preferred light polarization orthogonally oriented with respect to the preferred light polarization of other reflector, and said receiver includes means for heterodyning orthogonally polarized input signals.
Claim 8
Dependent Claim
32 words
The system of claim 6 wherein said dual-polarization laser is adjusted to have a predetermined frequency difference between said two outputs, and said receiver includes a demodulator tuned to said frequency difference.
Claim 9
Dependent Claim
113 words
An optical retrocommunications system comprising: a. a base terminal having an optical transmitter and an optical receiver, said transmitter producing at least two optical output beams orthogonally polarized with respEct to each other, said two beams having a predetermined optical frequency difference, said receiver having optical input means capable of heterodyning said two beams to produce an electrical signal having a frequency equal to said optical frequency difference, said receiver including demodulator means tuned to said electrical signal, and a. a remote terminal having means for separately retroreflecting said two beams and means for varying the phase of reflection of one optical beam with respect to the phase of the other optical beam.
Claim 10
Dependent Claim
113 words
An optical retrocommunications system comprising: a. a base terminal having an optical transmitter and an optical receiver, said transmitter producing at least two optical output beams orthogonally polarized with respEct to each other, said two beams having a predetermined optical frequency difference, said receiver having optical input means capable of heterodyning said two beams to produce an electrical signal having a frequency equal to said optical frequency difference, said receiver including demodulator means tuned to said electrical signal, and a. a remote terminal having means for separately retroreflecting said two beams and means for varying the phase of reflection of one optical beam with respect to the phase of the other optical beam.
Claim 11
Dependent Claim
38 words
The system of claim 8 wherein said remote terminal comprises two retroreflectors, and said means for varying the phase of reflection includes means for moving at least one of said retroreflectors in accordance with a desired information signal.
Claim 12
Dependent Claim
41 words
The system of claim 8 wherein said remote terminal comprises two retroreflectors, and said means for varying the phase of reflection includes an electro optical device having the capability of varying the optical path length in accordance with an electrical signal.
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) | 1978-01-27 | 1978-07-29 | 1979-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-27 | 1982-07-29 | 1983-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-27 | 1986-07-29 | 1987-01-28 | $7700.00 | Window Closed / Lapsed |