Acousto-optical signal processing system

Claim 2

An acousto-optical signal processing system comprising: a light source; a light modulator positioned to receive light from said source and having a light-transmitting compressional wave medium therein, and a pair of electroacoustic transducers for generating oppositely directed compressional waves in said medium transverse to the direction of light transmission therethrough; oscillator means for energizing said transducers in phase and at the same frequency, signal input means for amplitude modulating the oscillations applied to at least one of said transducers; an optical system for imaging onto an image plane the light transmitted through the modulator which is deflected by said compressional waves; and light-responsive, time-integrating detector means at the image plane extending over at least a substantial portion of the image thereat of the light transmitted through the modulator and deflected by said compressional waves.

Claim 3

A system according to claim 1, wherein said detector means is an imaging detector which provides a point-for-point correspondence of the light image thereat with the light output intensity along said modulator transverse to the direction of the light transmission therethrough.

Claim 4

A system according to claim 1, wherein said oscillator means operates at a constant frequency, and said input signal means comprises a first signal source which amplitude modulates the oscillations applied to one of said transducers, and a reference signal source which amplitude modulates the oscillations applied to the other of said transducers.

Claim 5

A system according to claim 1, wherein the frequency of said oscillator means varies with time cyclically, and said input signal means comprises a signal source which amplitude modulates the oscillations applied to one of said transducers, and the oscillations applied to the other of said transducers are unmodulated.

Claim 6

A signal-processing system according to claim 2, wherein said detector means has a light integration time substantially longer than the time for propagation of a compressional wave through the modulator.

Claim 7

A signal-processing system according to claim 5, wherein said detector means is a television picture pickup tube.

Claim 8

A signal-processing system according to claim 2, wherein said optical system includes an optical grating having grating lines disposed at an acute angle to the spatial carrier light output from the modulator.

Claim 9

A signal-processing system according to claim 1, and further comprising light reflecting means at the modulator for causing the light to pass more than once through said medium transverse to said compressional waves before reaching said optical system.

Claim 10

An acousto-optical signal-processing system comprising: a light modulator cell having an entry window and an exit window and filled with a light-transmitting elastic medium for transmitting light between said windows, a first electromechanical transducer at one end of the cell for generating a first compressional wave in said medium transverse to the light transmitted therethrough, and a second electromechanical transducer at the opposite end of said cell for generating a second compressional wave in said medium in a direction substantially opposite to that of the first compressional wave; oscillator means for energiZing said transducers in phase and at the same instantaneous frequency, signal input means for amplitude modulating the oscillations applied to at least one of said transducers; a light source for passing light through said cell from said entry window to said exit window to be phase modulated by said compressional waves so that the light output from the cell contains a uniform plane wave component and additional components which are deflected by the compressional waves; an optical system at the output side of the cell including a stop, lens means for focusing said uniform plane wave component on said stop and for imaging said additional deflected components on an image plane to provide a point-for-point correspondence of the light intensity of said additional components in said image plane with their intensity along the cell at said exit window; time-integrating light-responsive detector means at said image plane having an integration time substantially longer than the time for propagation of a compressional wave through the medium in the light modulator cell from one end of the cell to the other; and electrical filter means connected to the output of said detector means for rejecting components of the light at said image plane other than the spatial carrier modulated by a cross-correlation function of the signals applied to said transducers in the cell.

Claim 11

An acousto-optical signal-processing system comprising: a light modulator cell having an entry window and an exit window and filled with a light-transmitting elastic medium for transmitting light between said windows, a first electromechanical transducer at one end of the cell for generating a first compressional wave in said medium transverse to the light transmitted therethrough, and a second electromechanical transducer at the opposite end of said cell for generating a second compressional wave in said medium in a direction substantially opposite to that of the first compressional wave; oscillator means for energiZing said transducers in phase and at the same instantaneous frequency, signal input means for amplitude modulating the oscillations applied to at least one of said transducers; a light source for passing light through said cell from said entry window to said exit window to be phase modulated by said compressional waves so that the light output from the cell contains a uniform plane wave component and additional components which are deflected by the compressional waves; an optical system at the output side of the cell including a stop, lens means for focusing said uniform plane wave component on said stop and for imaging said additional deflected components on an image plane to provide a point-for-point correspondence of the light intensity of said additional components in said image plane with their intensity along the cell at said exit window; time-integrating light-responsive detector means at said image plane having an integration time substantially longer than the time for propagation of a compressional wave through the medium in the light modulator cell from one end of the cell to the other; and electrical filter means connected to the output of said detector means for rejecting components of the light at said image plane other than the spatial carrier modulated by a cross-correlation function of the signals applied to said transducers in the cell.

Claim 12

A signal-processing system according to claim 9, wherein said oscillator means provides fixed-frequency oscillations for both transducers in the cell, and the oscillations applied to both transducers are amplitude modulated respectively by different input signals which are to be cross-correlated.

Claim 13

A signal-processing system according to claim 9, wherein said oscillator means provides oscillations whose frequency varies with time over a selected spectrum, the oscillations applied to the second transducer have a substantially constant amplitude, and the oscillations applied to the first transducer are amplitude modulated by a signal which is to be analyzed in said spectrum.

Claim 14

A signal-processing system according to claim 9, wherein said optical system includes an optical grating having a series of grating lines extending at an acute angle to the spatial carrier to produce an interference effect for providing a lower frequency modified spatial carrier at a substantial angle with respect to the cross-correlation function modulating signal.

Claim 15

A signal-processing system according to claim 9, wherein said detector means is a television picture pickup tube.

Claim 16

A signal-processing system according to claim 13, wherein said optical system includes an optical grating having a series of grating lines extending at an acute angle to the spatial carrier to produce an interference effect for providing a lower frequency modified spatial carrier at a substantial angle with respect to the cross-correlation function modulating signal.

Claim 17

A signal-processing system according to claim 9, and further comprising light reflector means at the cell for causing the light to pass across the cell more than once through said medium between said entry and exit windows.

Claim 18

A signal-processing system according to claim 15, wherein said light reflector means comprises reflectors at the opposite sides of the cell in the path of the light passing through said medium from said entry window to said exit window.