Patent DE1198328B successfully refreshed from Google Patents.
US3694656A
Expired / Lapsed
US
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Balanced optical demodulator
Assignee: Raytheon Co
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Filing: 1970-10-28
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Granted: 1972-09-26
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Expires: 1990-10-28
Abstract
Abstract A demodulator for optical signals, the contemplated demodulator including a polarizer and mirror arrangement for combining the signals to be demodulated and optical local oscillator signals into a first and a second composite beam, the first beam being modulated in a manner corresponding to the algebraic sum of the signals to be detected and the optical local oscillator signals and the second beam being modulated in a manner corresponding to the algebraic difference between such signals. Each composite beam is directed to a different photodetector and the difference signal between the electrical output signals of the photodetectors is derived. Such difference signal, which is proportional only to the product of the signals to be demodulated and a constant related to the optical local oscillator signals, may then be processed to derive the desired demodulated signals.
Inventors
- 👤 Harley B Henning
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 18:15
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/60; G; G01; G01S; G01S7/00; G01S7/48; G01S7/499; G02; G02F; G02F2/00; G02F2/002
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
247 words
In a demodulator wherein an electrical signal representative of the product of two optical signals from different sources is derived, the improvement comprising: a. first and second polarizer means, each responsive to a different one of the two optical signals, for producing separate linearly polarized optical signals having mutually orthogonal polarizations; b. means for forming first and second composite optical signals from the linearly polarized optical signals, such first and second composite optical signals being substantially identical to one another; c. third and fourth polarizer means, responsive respectively to the first and the second composite optical signals, for forming third and fourth composite optical signals, the third composite optical signals being indicative of the sum of the linearly polarized optical signals in the first composite optical signals and the fourth composite optical signals being indicative of the difference between the linearly polarized optical signals in the second composite optical signals; d. photodetector means, responsive respectively to the third and the fourth composite optical signals, for producing first and second electrical signals, the first electrical signals being indicative of the square of the sum of the linearly polarized optical signals in the first composite optical signals and the second electrical signals being indicative of the square of the difference of the linearly polarized optical signals in the second composite optical signals; and e. differencing means, responsive to the first and the second electrical signals, for producing third electrical signals indicative of the product of the two optical signals.
Claim 2
Dependent Claim
247 words
In a demodulator wherein an electrical signal representative of the product of two optical signals from different sources is derived, the improvement comprising: a. first and second polarizer means, each responsive to a different one of the two optical signals, for producing separate linearly polarized optical signals having mutually orthogonal polarizations; b. means for forming first and second composite optical signals from the linearly polarized optical signals, such first and second composite optical signals being substantially identical to one another; c. third and fourth polarizer means, responsive respectively to the first and the second composite optical signals, for forming third and fourth composite optical signals, the third composite optical signals being indicative of the sum of the linearly polarized optical signals in the first composite optical signals and the fourth composite optical signals being indicative of the difference between the linearly polarized optical signals in the second composite optical signals; d. photodetector means, responsive respectively to the third and the fourth composite optical signals, for producing first and second electrical signals, the first electrical signals being indicative of the square of the sum of the linearly polarized optical signals in the first composite optical signals and the second electrical signals being indicative of the square of the difference of the linearly polarized optical signals in the second composite optical signals; and e. differencing means, responsive to the first and the second electrical signals, for producing third electrical signals indicative of the product of the two optical signals.
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) | 1975-09-26 | 1976-03-27 | 1976-09-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-26 | 1980-03-27 | 1980-09-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-26 | 1984-03-27 | 1984-09-26 | $7700.00 | Window Closed / Lapsed |