Acoustic wave imaging apparatus and method

Abstract

An acoustic imaging apparatus and method that achieves desired delays with coded signals. Linear, curved linear and sector scanning is provided in 1-D arrays and planar, curved planar and sector scanning is provided in 2-D arrays. Composite and non-linear implementations are presented. Dynamic and discrete dynamic focusing is disclosed for the relevant arrays. The 2-D array makes possible 3-D imaging.

1. An acoustic imaging apparatus, comprising:
 control logic;  
 a plurality of transducer elements arranged in an array, each coupled to said control logic and capable of transmitting an acoustic signal representative of an electrical transmit control signal propagated from said control logic and generating an electrical receive signal representative of an incident acoustic signal;  
 means within said control logic for generating an electrical transmit control signal for each transducer element such that the electrical transmit control signal for each transducer element contains a coded signal;  
 means within said control logic for generating an electrical receive control signal for each transducer element such that the electrical receive control signal for each transducer element contains a frequency and phase shift than when combined with the transducer element's electrical receive signal modifies the frequency and phase of that electrical receive signal in such a manner as to permit the coherent combination of the modified electrical receive signals from all of said plurality of transducer elements;  
 means for combining the electrical receive control signal of each transducer element with an electrical receive signal generated by that transducer;  
 means coupled to each of said transducer elements for combining the modified electrical receive signals from said transducer elements so as to form a coherently combined array output signal;  
 means coupled to said transducer output combining means for decoding a combined reflected coded signal in the coherently combined array output signal to produce a decoding means output signal; and means coupled to said decoding means for generating image data from said decoding means output signal.  
 
     
     
       2. The apparatus of  claim 1 , wherein said coded signal is a chirp. 
     
     
       3. The apparatus of  claim 2 , wherein said decoding means comprises at least one matched filter for coded signal decoding. 
     
     
       4. The apparatus of  claim 1 , wherein said chirp is a linear FM chirp. 
     
     
       5. The apparatus of  claim 1 , wherein said array has a size of M rows and N columns and said electrical transmit control signal generating means comprises means for generating individual row and column transmit control signals for each of said rows and columns, the electrical transmit control signal for each transducer element being a combination of the transmit row and column control signals for that transducer. 
     
     
       6. The apparatus of  claim 5 , wherein at least one of said row and column transmit control signals for a given transducer element contains a frequency based coded signal. 
     
     
       7. The apparatus of  claim 5 , wherein said electrical receive control signal generating means comprises means for generating individual row and column receive control signals for each of said rows and columns, the electrical receive control signal for each transducer being a combination of the receive row and column control signals for that transducer. 
     
     
       8. The apparatus of  claim 1 , wherein said coded signal includes a frequency based code. 
     
     
       9. The apparatus of  claim 1 , wherein said array is a one dimensional array with a plurality of rows and one column. 
     
     
       10. The apparatus of  claim 1 , wherein said array of transducer elements comprises M rows and N columns, where M and N are positive integers and at least one of M and N is greater than 1;
 at least one of said transmit control signal generating means and said receive control signal generating means includes means for generating row and column control signal components; and  
 wherein each transducer element includes an active electronic device for combining said row and column control signal components for that transducer element.  
 
     
     
       11. The apparatus of  claim 1 , wherein each transducer element includes a transducer comprised of a non-linear electro-acoustic, non-linear dielectric material. 
     
     
       12. An acoustic imaging apparatus, comprising:
 a plurality of electro-acoustic transducer elements arranged in an array, each capable of transmitting an acoustic signal and generating an electrical signal representative of an incident acoustic wave;  
 control means having a plurality of control channels coupled to each of said plurality of transducer elements, said control channels being fewer in number than said transducer elements;  
 wherein said control means generates control signals for each transducer element that when combined with the electrical receive signal of that transducer element modifies the electrical receive signal in such a manner as to permit the simultaneous processing of the modified electrical receive signals from said plurality of transducer elements;  
 means for combining the modified electrical receive signals of each of said transducer elements to form an array output signal; and  
 means coupled to said combining means for generating image data from said array output signal.  
 
     
     
       13. The apparatus of  claim 12 , wherein said array has a plurality of rows and a plurality of columns each having one of said plurality of control channels associated therewith;
 said control signal generating means further including means for generating row and column control signal components; and  
 wherein said transducer element is uniquely and simultaneously controlled by a combination of the row and column control signal components for that transducer element.  
 
     
     
       14. The apparatus of  claim 12 , wherein said control signal generating means further includes means for generating a transmit control signal for each transducer element that contains a frequency based coded signal for transmission by each transducer element. 
     
     
       15. The apparatus of  claim 14 ,
 further comprising means for decoding a reflected frequency based coded signal.  
 
     
     
       16. An acoustic imaging system, comprising:
 an array of electro-acoustic transducer elements having M rows and N columns, where M and N are positive integers and at least one of M and N is greater than one;  
 M row control lines, each coupled to the transducer elements in one of said M rows;  
 N column control lines, each coupled to the transducer elements in one of said N columns;  
 control means coupled to each of said M row and N column control lines for generating row control signals for each of said row control lines and column control signals for each of said column control lines, a control signal for each transducer being a combination of one of said row control signals and one of said column control signals;  
 a plurality of active devices, each coupled to one of said transducer elements for combining the row control signal and the column control signal of that transducer element;  
 means for combining the output of each transducer element to produce an array output signal; and  
 means coupled to said transducer output combining means for generating image data from said array output signal.  
 
     
     
       17. The apparatus of  claim 16 , wherein said active device is an active electronic device. 
     
     
       18. The apparatus of  claim 17 , wherein said control means includes means for generating a transmit control signal that contains a frequency based coded signal for each transducer element; and
 wherein said apparatus further comprises means in communication with each of said transducer elements for modifying a reflected coded signal received thereby to achieve a delay encoded in the coded signal, said delay for each transducer element being based on the relative position of that transducer element in the array.  
 
     
     
       19. The apparatus of  claim 16 , wherein said active device includes a non-linear electro-acoustic material. 
     
     
       20. The apparatus of  claim 16 , wherein said active device includes a non-linear electro-acoustic material for combining row and column control signal on transmit and an active electronic device for combining row and column control signal on receive. 
     
     
       21. The apparatus of  claim 16 , wherein said active device includes a non-linear electro-acoustic, nonlinear dielectric material. 
     
     
       22. A method for acoustic imaging, comprising the steps of:
 providing control logic;  
 providing a plurality of transducer elements arranged in an array, each coupled to said control logic and capable of transmitting an acoustic signal representative of an electrical transmit control signal propagated from said control logic and generating an electrical receive signal representative of an incident acoustic signal;  
 generating an electrical transmit control signal for each transducer element such that the electrical transmit control signal for each transducer element contains a coded signal;  
 generating an electrical receive control signal for each transducer element that contains an appropriate frequency and phase shift that when combined with that transducer element's electrical receive signal permits the coherent combination of the electrical receive signals of each of the plurality of transducer elements;  
 combining the coherent output signals from said transducer elements so as to form a coherently combined array output signal;  
 decoding a combined reflected coded signal in the coherently combined array output signal to produce a decoded output signal; and  
 generating image data from the decoded output signal.  
 
     
     
       23. An acoustic imaging apparatus, comprising:
 control logic;  
 a plurality of transducer elements arranged in an array, each coupled to said control logic and capable of transmitting an acoustic signal representative of an electrical transmit control signal propagated from said control logic and generating an electrical receive signal representative of an incident acoustic signal;  
 means within said control logic for generating an electrical transmit control signal for each transducer element that contains a frequency based coded signal and cause  causing each transducer to emit an acoustic signal representative of said coded signal;  
 means for modifying the frequency and chase  phase of an electrical receive signal of each transducer element for coherently combining reflected coded signals within the electrical receive signals thereof;  
 means coupled to said modifying means for decoding the combined reflected coded signals to achieve a time delay based on that coded signal; and  
 means coupled to said decoding means for generating image data from an output signal therefrom.  
 
     
     
       24. An acoustic energy transmitting apparatus, comprising:
   a plurality of electro - acoustic transducer elements arranged in an M row by N column array, where M and N are positive integers and at least one of M and N is greater than one;        control circuit for propagating row and column control signals for each of said M rows and said N columns, each control signal having a frequency and a phase component; and        wherein each transducer element is configured to function as an active device so as to achieve a combining at each transducer element of the frequency and phase components of the row and column control signals for that transducer element in such a manner as to provide a focused acoustic signal at a given focal distance and direction from said array.     
     
     
       25. The apparatus of  claim 24 , wherein the electric signal to acoustic signal relationship and vice versa of each transducer element is non- linear.   
     
     
       26. The apparatus of  claim 24 , wherein said control circuit includes a control channel for each of said M rows and a control channel for each of said N columns, and wherein the number of control channels is fewer than the number of transducer elements. 
     
     
       27. The apparatus of  claim 24 , wherein said control circuit is configured such that the row and column signals for at least some of the transducer elements includes a coded signal. 
     
     
       28. The apparatus of  claim 27 , wherein M equals one. 
     
     
       29. An acoustic energy transmitting apparatus, comprising:
   a plurality of electro - acoustic transducer elements arranged in an M row by N column array, where M and N are positive integers and at least one of M and N is greater than one;        M row control lines, each coupled to the transducer elements in one of said M rows;        N column control lines, each coupled to the transducer elements in one of said N columns;        control circuit for propagating row and column control signals for each of said M rows and said N columns, a control signal for each transducer element being a combination of one of said row control signals and one of said column control signals;        a plurality of active devices, each coupled to one of said transducer elements for combining the row control signal and the column control signal of that transducer element;        wherein said transducer elements, control circuit and active devices are configured so as to achieve a combining at each transducer element of the row and column control signals for that transducer element in such a manner as to provide a focused acoustic signal at a given focal distance and direction from said array; and        wherein each of said electro - acoustic transducer elements is configured within said apparatus to function in a non - linear manner in operation.     
     
     
       30. An acoustic energy receiving apparatus, comprising:
   a plurality of electro - acoustic transducer elements arranged in an M row by N column array;        control circuit for propagating row and column control signals for each of said M rows and said N columns, each row and column control signal having a frequency and a phase component; and        wherein said transducer elements and said control circuit are configured so as to achieve a combining at each transducer element of the frequency and phase components of the row and column control signals for that transducer element with a resultant electrical receive signal, corresponding to an acoustic signal incident on that transducer element, in such a manner as to modify the frequency and phase of the transducer element's electrical receive signal so as to achieve the coherent combination of the modified electrical receive signals from all of said plurality of transducer elements; and        a filter that filters spurious frequencies output from the transducer elements;        wherein said transducer elements, control circuit and filter are configured to achieve focused acoustic signal reception at a given distance and direction from said array.     
     
     
       31. The apparatus of  claim 30 , wherein said transducer elements and said control circuit are configured to achieve dynamic focused acoustic signal reception. 
     
     
       32. The apparatus of  claim 31 , wherein the electric signal to acoustic signal relationship and vice versa of each transducer element is non- linear.   
     
     
       33. The apparatus of  claim 30 , wherein said filter includes a matched filter. 
     
     
       34. The apparatus of  claim 33 , wherein said matched filter includes a conjugate of a coded signal. 
     
     
       35. The apparatus of  claim 29 , wherein M equals one. 
     
     
       36. The apparatus of  claim 30 , further comprising a circuit that generates image data from the coherent combination of transducer element receive signals. 
     
     
       37. The apparatus of  claim 30 , wherein said control circuit includes a control channel for each of said M rows and a control channel for each of said N columns, and wherein the number of control channels is fewer than the number of transducer elements. 
     
     
       38. An acoustic energy receiving apparatus, comprising:
   a plurality of electro - acoustic transducer elements each capable of generating an electrical receive signal in response to an incident acoustic wave and arranged in an M row by N column array, where M and N are positive integers and at least one of M and N is greater than one;        control circuit for propagating row and column control signals for each of said M rows and said N columns, the control signal for each transducer element being a combination of the row and column control signals for that transducer element;        wherein said row and column control signals are configured, for each transducer element, such that when combined with the electrical receive signal of that transducer element the electrical receive signal is modified in such a manner as to permit the simultaneous processing of the modified electrical receive signals from said plurality of transducer elements;        a first circuit that combines the modified electrical receive signals of each of said transducer elements to form an array output signal; and        a second circuit coupled to said first circuit that generates image data from said array output signal.     
     
     
       39. The apparatus of  claim 38 , wherein M equals one. 
     
     
       40. The apparatus of  claim 24 , wherein each transducer element includes non- linear electro - acoustic material.