US4636718A
Expired / Lapsed
US
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Acousto-optical spectrum analyzer with expanded frequency resolution
Assignee: Unisys Corp
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Filing: 1984-07-20
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Granted: 1987-01-13
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Expires: 2004-07-20
Abstract
Abstract This invention is directed to a spectrum analyzer system which is laser-driven and which includes a standard Bragg cell and a standard photo-diode array as the output detector. In this system, the Bragg cell is driven by a bandwidth expansion circuit which receives the typical R.F. input signal, supplies it to a variable center frequency filter or to a bank of filters which then down-converts the signal and supplies the signal to a real time signal storage memory at a first signal rate. The signals are retrieved from the memory at a second, much greater signal rate, up-converted and supplied to the Bragg cell to affect the operation thereof in the usual fashion. This time base compression circuit has the effect of producing an improved optical spectrum analyzer with expanded frequency resolution.
Inventors
- 👤 Joseph H. Labrum
- 👤 Allen D. Wilcox
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:03
CPC Classifications
G; G01; G01R; G01R23/00; G01R23/16; G01R23/165; G01R23/17
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
170 words
An acousto-optical spectrum analyzer comprising, first source means for providing an electromagnetic wave, acousto-optic cell means for operating on said electromagnetic wave, optical means disposed intermediate said acousto-optic cell and said detector means to operate on focusing of said electromagnetic wave, dectector means for detecting said electromagnetic wave after operation thereon by said acousto-optic cell, bandwidth expansion means connected to said acousto-optic cell to control the operation thereof, said bandwidth expansion means including storage means capable of a rate of read-out which is higher than the rate of read-in, first oscillator means, first mixer means for combining the signal from said first oscillator means and the output signal from said storage means to produce a control signal to be applied to said acousto-optic cell means, second source means for providing an R.F. input signal, second oscillator means, and second mixer means for combining the signal from said second source means and the signal from said second oscillator means to produce an input signal to be stored in said storage means.
Claim 2
Dependent Claim
170 words
An acousto-optical spectrum analyzer comprising, first source means for providing an electromagnetic wave, acousto-optic cell means for operating on said electromagnetic wave, optical means disposed intermediate said acousto-optic cell and said detector means to operate on focusing of said electromagnetic wave, dectector means for detecting said electromagnetic wave after operation thereon by said acousto-optic cell, bandwidth expansion means connected to said acousto-optic cell to control the operation thereof, said bandwidth expansion means including storage means capable of a rate of read-out which is higher than the rate of read-in, first oscillator means, first mixer means for combining the signal from said first oscillator means and the output signal from said storage means to produce a control signal to be applied to said acousto-optic cell means, second source means for providing an R.F. input signal, second oscillator means, and second mixer means for combining the signal from said second source means and the signal from said second oscillator means to produce an input signal to be stored in said storage means.
Claim 3
Dependent Claim
15 words
The analyzer recited in claim 1 wherein, said electromagnetic wave is an optical frequency transform.
Claim 4
Dependent Claim
22 words
The analyzer recited in claim 2 wherein, said detector means disposed to operate at the Fourier transform plane of said electromagnetic wave.
Claim 5
Dependent Claim
20 words
The analyzer recited in claim 1 wherein, said bandwidth expansion means supplies an RF input signal to said acousto-optic cell.
Claim 6
Dependent Claim
15 words
The analyzer recited in claim 1 wherein, said acousto-optic cell means is a Bragg cell.
Claim 7
Dependent Claim
13 words
The analyzer recited in claim 1 wherein, said source means comprises a laser.
Claim 8
Dependent Claim
14 words
The analyzer recited in claim 1 wherein, said detector means comprises a photo-diode array.
Claim 9
Dependent Claim
27 words
The analyzer recited in claim 1 including, multiplexer means connected to said acousto-optic cell to selectively connect portions of said bandwidth expansion means to said acousto-optic cell.
Claim 10
Dependent Claim
14 words
The analyzer recited in claim 1 wherein, said storage means comprises a memory device.
Claim 11
Dependent Claim
14 words
The analyzer recited in claim 9 wherein, said memory device is a digital memory.
Claim 12
Dependent Claim
34 words
The analyzer recited in claim 10 including, analog to digital converter means connected to the input of said digital memory, and digital to analog converter means connected to the output of said digital memory.
Claim 13
Dependent Claim
19 words
The analyzer recited in claim 1 including, filter means connected between said second mixer means and said storage means.
Claim 14
Dependent Claim
16 words
The analyzer recited in claim 1 wherein, said storage means comprises a charge coupled device (CDC).
Claim 15
Dependent Claim
18 words
The analyzer recited in claim 1 wherein, said bandwidth expansion means includes a variable center frequency filter means.
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) | 1990-01-12 | 1990-07-14 | 1991-01-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-12 | 1994-07-14 | 1995-01-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-12 | 1998-07-14 | 1999-01-13 | $7700.00 | Window Closed / Lapsed |