Acoustic imaging apparatus

Claim 2

In a system for recording an acoustic hologram or image of an object by irradiating the object with acoustic waves of a predetermined frequency content to develop a field of acoustic vibrations in a selected surface plane beyond said object in the path of said acoustic waves, scanning the surface plane with a focused light beam and measuring variations in a reflection component of light from the surface plane, acousto-optic apparatus comprising: a medium, in which said object is immersed, propagative of said acoustic waves; means for launching said acoustic waves in said medium along at least one path toward said object; a layer of light-transparent material located on the side of said surface plane opposite said medium and having sufficient acoustic-wave attenuation in combination with its thickness to exhibit non-resonance to the acoustic energy; and a light-reflective coating on a surface of said layer located substantially in said surface plane.

Claim 3

A system as defined in claim 1 in which the path of said acoustic waves defines an acute angle with said surface plane.

Claim 4

A system as defined in claim 1 in which said launching means includes a transducer immersed in said medium and directing said acoustic waves toward said object at an acute angle to said surface plane.

Claim 5

A system as defined in claim 1 in which said launching means includes a transducer defining one wall of a chamber in which said medium is contained and oriented to direct said acoustic waves toward said object at an acute angle to said surface plane.

Claim 6

A system as defined in claim 1 in which said launching means includes a wave-transmission element acoustically coupled at one end to said medium and a transducer coupled to the opposite end of said element for delivering said acoustic waves into said element, said element exhibiting an attenuation to said acoustic waves substantially less than that of said medium.

Claim 7

A system as defined in claim 1 in which said launching means includes a substrate having a surface exposed to said medium and arranged parallel to said scanned surface plane along which sound waves travel in the surface-wave mode to develop said acoustic waves in a compressional wave mode propagating in said medium effectively along a pair of paths toward said object and at an acute angle to said surface plane.

Claim 8

A system as defined in claim 6 which further includes: an externally threaded plug the interior of which constitutes said layer and with said coating being affixed to said layer; and a collar threaded on said plug and defining a chamber within whiCh said medium and said substrate are disposed.

Claim 9

A system as defined in claim 7 in which said plug defines a passageway into which said medium is admitted as the plug is threaded into said collar.

Claim 10

A system as defined in claim 1 in which said layer defines a recess facing said medium, said coating is affixed in the bottom of said recess, and a medium-permeable member is disposed across said recess to define a chamber in which said object is disposed.

Claim 11

A system as defined in claim 1 in which a sheet of anisotropic material, of a thickness no greater than one-half acoustic wavelength at a frequency within said predetermined frequency content and exhibiting unequal strain optic coefficients in orthogonal directions parallel with said surface plane, is sandwiched between said coating and said surface of said layer.

Claim 12

A system as defined in claim 1 in which said launching means includes means for propagating sound waves in a direction generally parallel to said surface plane and for coupling said sound waves to said medium to develop said acoustic waves.

Claim 13

A system as defined in claim 11 wherein said propogating means includes a substrate having a surface exposed to said medium and along which said sound waves travel in the surface-wave mode to develop said acoustic waves in a compressional-wave mode.

Claim 14

A system as defined in claim 1 in which said means for measuring said variations includes means responsive to different Doppler shifts in said reflection component, corresponding respectively to different spectra of scattered waves of acoustic energy in respective different paths, for separating the respective different spectral information.

Claim 15

A system as defined in claim 1 wherein said acoustic waves propagate along a pair of paths that define respectively opposing acute angles to a normal to said surface plane.

Claim 16

In a system for recording an acoustic hologram or image of an object by irradiating the object with acoustic waves of a predetermined frequency content to develop a field of acoustic vibrations in a selected surface plane beyond said object in the path of said acoustic waves, scanning the surface plane with a focused light beam and measuring variations in a reflection component of light from the surface plane, acousto-optic apparatus comprising: a medium in which said object is immersed and which subjects said acoustic waves propagating therein to a predetermined attenuation per unit length; means for launching said acoustic waves along at least one path toward said object and at an acute angle to said surface plane, whereby acoustic waves in one portion of said path travel a greater distance to said surface plane than acoustic waves in a laterally spaced different portion of said path; compensating means included in said launching means for effectively equalizing the amplitude of said acoustic waves arriving at said surface plane in correspondence with the difference in attenuation of the waves in the respective ones of said path portions; and a light-reflective film located in said surface plane.

Claim 17

In a system for recording an acoustic hologram or image of an object by irradiating the object with acoustic waves of a predetermined frequency content to develop a field of acoustic vibrations in a selected surface plane beyond said object in the path of said acoustic waves, scanning the surface plane with a focused light beam and measuring variations in a reflection component of light from the surface plane, acousto-optic apparatus comprising: a medium in which said object is immersed and which subjects said acoustic waves propagating therein to a predetermined attenuation per unit length; means for launching said acoustic waves along at least one path toward said object and at an acute angle to said surface plane, whereby acoustic waves in one portion of said path travel a greater distance to said surface plane than acoustic waves in a laterally spaced different portion of said path; compensating means included in said launching means for effectively equalizing the amplitude of said acoustic waves arriving at said surface plane in correspondence with the difference in attenuation of the waves in the respective ones of said path portions; and a light-reflective film located in said surface plane.

Claim 18

A system as defined in claim 15 in which said compensating means includes a layer of material partially attenuative of said acoustic waves in an amount which varies substantially linearly in a direction lateral to said path and proportional to the decrease in distance of portions of said launching means for corresponding portions of said surface plane.

Claim 19

A system as defined in claim 15 in which said launching means includes a compressional-mode transducer coupled with an acoustic phase grating disposed substantially parallel to said scanned surface plane to direct acoustic energy toward said object.