Focused sonic imaging system

Claim 2

Apparatus for imaging ultrasonic reflections from an object comprising: a transducer for generating ultrasonic energy; a chirped signal source connected to the transducer to generate a chirped ultrasonic wave; a dispersive lens positioned in the path of the ultrasonic wave between the transducer and the object whose focal length varies with the frequency of the ultrasonic energy; means for receiving the chirped ultrasonic wave when it is reflected off the object to form a received chirped signal; means for processing the received chirped signal so that the portion of the received chirped signal being detected represents information from the plane at which the dispersive lens is in focus; and means for displaying the processed signal.

Claim 3

Apparatus as recited in claim 1 wherein the means for receiving the chirped ultrasonic wave includes the transducer used for generating the chirped ultrasonic wave and means for gating the transducer output so that the chirped signal source will be suppressed.

Claim 4

Apparatus as recited in claim 2 wherein the means for receiving the chirped ultrasonic wave further includes at least one additional transducer whose output is combined with that of the transducer used for generating the chirped ultrasonic wave.

Claim 5

Apparatus as recited in claim 1 wherein the means for processing the received chirped signal comprises: a mixer having on input terminal connected to the received chirped signal; a swept frequency oscillator connected to the second input terminal of the mixer; an intermediate frequency filter connected to the mixer output terminal; a quadratic phase filter connecting to the output of the intermediate frequency filter for generating an output signal corresponding to the amplitude of the reflections; and a detector for detecting the amplitude of the output signal.

Claim 6

Apparatus as recited in claim 4 wherein the instantaneous frequency of the swept frequency oscillator translates that portion of the spectrum of the received chirped signal into the passband of the intermediate frequency filter corresponding to the plane at which the dispersive lens is in focus.

Claim 7

Apparatus as recited in claim 1 wherein the dispersive lens is made of a material whose velocity of propagation varies with frequency.

Claim 8

Apparatus as recited in claim 1 wherein the dispersive lens includes a Fresnel zone plate structure containing concentric rings whose periodicity increases linearly with radius.

Claim 9

Apparatus as recited in claim 7 wherein the Fresnel zone plate structure contains alternate rings of material having varying degress of attenuation of the sound energy.

Claim 10

Apparatus as recited in claim 7 wherein the Fresnel zone plate structure contains alternate rings of material having varying phase shifts to the sound energy.

Claim 11

Apparatus as recited in claim 9 in which the alternate rings have a parabolic thickness change with radius.

Claim 12

Apparatus as recited in claim 7 wherein a refractive lens is placed adjacent to the Fresnel zone plate structure to form a combination lens.

Claim 13

Apparatus as recited in claim 11 in which the combination lens has a focal length which increases with decreasing frequency.

Claim 14

Apparatus as recited in claim 7 wherein an absorption pad is placed along the axis of the lens to absorb the undesired modes.

Claim 15

Apparatus as recited in claim 1 wherein the means for displaying the processed signal includes a video storage tube for storing the processed signal in an array of modulated raster lines as it is received and means for reading out the stored image at television rates.

Claim 16

Apparatus as recited in claim 14 including means for varying the amplitude of the processed signal applied to the video storage tube directly with the velocity at which the transducer is moved.

Claim 17

Apparatus for imaging ultrasonic reflections from an object comprising: an array of transducers for generating and receiving ultrasonic energy; a chirped signal source connected to each transducer in the array; a dispersive lens positioned in the ultrasonic path between the array of transducers and the object whose focal length varies with the frequency of the ultrasonic energy; means for receiving the reflected chirped ultrasonic waves at each transducer in the array to form a plurality of received chirped signals; means for processing the plurality of received chirped signals so that the portion of each received chirped signal being detected at any time represents information from the plane at which the dispersive lens is in focus; and means for displaying the plurality of processed signals.

Claim 18

Apparatus for imaging ultrasonic reflections from an object comprising: an array of transducers for generating and receiving ultrasonic energy; a chirped signal source connected to each transducer in the array; a dispersive lens positioned in the ultrasonic path between the array of transducers and the object whose focal length varies with the frequency of the ultrasonic energy; means for receiving the reflected chirped ultrasonic waves at each transducer in the array to form a plurality of received chirped signals; means for processing the plurality of received chirped signals so that the portion of each received chirped signal being detected at any time represents information from the plane at which the dispersive lens is in focus; and means for displaying the plurality of processed signals.

Claim 19

Apparatus as recited in claim 16 including means for sequentially switching the chirped signal source amongst the array of transducers and wherein the means for processing the plurality of received chirped signals includes means for sequentially switching the input to a processor amongst the plurality of received chirped signals.