Ultrasonic camera

• US 6,159,149 A
• Filed: 03/28/1998
• Issued: 12/12/2000
• Est. Priority Date: 03/22/1996
• Status: Expired due to Term

• Current Assignee: Lockheed Martin IR Imaging Systems, Inc. (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Erikson, Kenneth R., White, Timothy E., Butler, Neal R., Owen, R. Calvin Jr., Nicoli, Anthony M.
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): PATEL, MAULIN M
• Application Number:
  US09/050,224
• Time in Patent Office: 990 Days
• Field of Search: 600/437, 600/438, 600/447, 600/448, 600/455
• US Class Current: 600/437
• CPC Class Codes: A61B 8/4281 characterised by sound-transmitting media or devices for coupling the transducer to the tissue
• CPC Class Codes: A61B 8/4483 characterised by features of the ultrasound transducer
• CPC Class Codes: B06B 1/0629 Square array
• CPC Class Codes: G01S 15/8925 the array being a two-dimensional transducer configuration, i.e. matrix or orthogonal linear arrays
• CPC Class Codes: G10K 11/02 Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators
• CPC Class Codes: G10K 11/30 using refraction, e.g. acoustic lenses

Abstract

An ultrasonic camera having a high efficiency ultrasonic lens is coupled to a ultrasonic transmitter/receiver by a stretched membrane interface. The ultrasonic lens provides highly efficient transmission of ultrasound without introducing aberrations. The ultrasound system also uses a quasi incoherent source to reduce speckle noise in the image.

Claims

1. An ultrasonic camera comprising:

(a) a camera housing;

(b) a means for generating quasi incoherent ultrasonic energy connected to the camera housing;

(c) means for collecting ultrasonic energy at high efficiency with high accuracy, connected to the camera housing;

(d) means for transducing the collected ultrasonic energy into electrical signals; and

(e) means for processing the electrical signals into an image.

2. The apparatus of claim 1 further comprising a means for generating ultrasonic energy connected to the camera housing.

3. The apparatus of claim 1 further comprising a means for transmitting ultrasonic energy, at high efficiency, connected to the camera housing.

4. The apparatus of claim 1 further comprising a means for conducting the collected ultrasonic energy.

5. The apparatus of claim 1 further comprising a means for displaying the image.

6. The apparatus of claim 1 wherein the means for generating quasi incoherent ultrasonic energy further comprises a plurality of ultrasonic transmitters.

7. The apparatus of claim 6 wherein each one of the plurality of ultrasonic transmitters has a different angle of insonification.

8. The apparatus of claim 7 wherein the plurality of ultrasonic transmitters are positioned around the means for collecting ultrasonic energy so as to provide at least one principal angle of insonification different from a second principal angle of insonification.

9. The apparatus of claim 7 wherein each one of the plurality of ultrasonic transmitters are driven sequentially to produce a separate images.

10. The apparatus of claim 9 further comprising a means for converting the separate images into a single image.

11. The apparatus of claim 10 wherein the signal processing further averages two or more of the separate images.

12. The apparatus of claim 1 wherein a single ultrasonic transmitter is sequentially mechanically moved to a new angle of insonification.

13. The apparatus of claim 12 further comprising a signal processing means for converting the sequential images to produce an image.

14. The apparatus of claim 1 wherein a multiple element transmitter array is sequentially electronically steered to a new angle of insonification.

15. The apparatus of claim 14 further comprising a means for signal processing to convert the sequential images to produce an image.

16. The apparatus of claim 1 wherein the means for generating ultrasonic energy further comprises a plurality of groups of transmitters, wherein all transmitters in a group are driven with a drive signal.

17. The apparatus of claim 16 wherein the plurality of groups of transmitters comprise an array of transmitters wherein members of each group are randomly distributed across the array.

18. The apparatus of claim 16 wherein transmitters in a group are distributed in a predetermined pattern.

19. The apparatus of claim 18 wherein the transmitters in a group are distributed randomly.

20. The apparatus of claim 18 wherein the transmitters are arranged in a linear arrangement.

21. The apparatus of claim 18 wherein the transmitters are arranged in a two dimensional matrix.

22. The apparatus of claim 18 wherein each group of transmitters is sequentially driven.

23. The apparatus of claim 22 wherein each group is sequentially driven with one or more electrical pulses.

24. The apparatus of claim 22 wherein each group is sequentially driven with an electrical sine wave burst.

25. The apparatus of claim 22 further comprising a signal processing means for converting the sequential images to produce an image of high quality.

26. The apparatus of claim 16 wherein groups of transmitters are constructed with different mechanical characteristics.

27. The apparatus of claim 26 wherein the different mechanical characteristics are achieved through different resonance frequencies.

28. The apparatus of claim 26 wherein the different mechanical characteristics are achieved through different vertical spacings.

29. The apparatus of claim 26 wherein the groups of transmitters are driven by a drive signal electrical pulse.

30. The apparatus of claim 26 wherein the groups of transmitters are driven by a drive signal comprising a sine wave burst with a frequency that corresponds to a resonance frequency of the transmitters in each group.

31. The apparatus of claim 26 wherein the groups of transmitters are driven by a drive signal having an electrical sine wave burst of a single frequency.

32. The apparatus of claim 1 further comprising an acoustic interface to conduct the collected ultrasonic energy into the transducing means and to provide mechanical isolation of the transduction circuitry from an ultrasonic fluid.

33. The apparatus of claim 32 wherein the acoustic interface further comprises:

(a) a mount having a flat surface surrounding an opening through the mount;

(b) a membrane stretched over the flat surface; and

(c) a retaining means for retaining the membrane attached to the mount wherein the membrane is held taut to the mount by the retaining means.

34. The apparatus of claim 33 wherein the flat surface provides a mechanical interface assuring six dimensional (X, Y, Z, roll, pitch, yaw) alignment of the collection means to the means for transducing.

35. The apparatus of claim 33 wherein the opening through the mount provides unimpeded acoustical contact of the means for transducing to the membrane.

36. The apparatus of claim 32 further comprising an oil film between the acoustic interface and the means for transducing.

37. The apparatus of claim 32 further comprising a gel film between the acoustic interface and the means for transducing.

38. The apparatus of claim 1 wherein the means for transducing the conducted electronic energy into electrical signals is comprised of a low volume fraction piezoelectric composite material in combination with a low capacitance electrical bump bond interconnection to a low stray capacitance preamplifier integrated circuit.

39. The apparatus of claim 1 wherein the means for transducing also transmits ultrasound.

44. The ultrasonic camera of claim 2 wherein the means for generating ultrasonic energy further comprises:

(a) a plurality of ultrasonic transducers, each of the plurality of ultrasonic transducers having a common electrode end and an individually isolated driving layer end wherein each one of the plurality of ultrasonic transducers are divided into subelements;

(b) a means for bump bonding each one of the plurality of ultrasonic transducers to a substrate; and

(c) a high voltage electrical conductor connected to at least one individually isolated driving layer end to provide a drive signal to at least one of the plurality of ultrasonic transducers.

45. The apparatus of claim 44 wherein the means for bump bonding each one of the plurality of ultrasonic transducers to a substrate further comprises an indium bump, solder bump or other electrically conductive material, wherein the indium bump comprises an area in contact with an ultrasonic transducer of less than 20 per cent of the individually isolated driving layer end of the ultrasonic transducer.

46. The apparatus of claim 44 wherein the substrate further comprises a semiconductor.

47. The apparatus of claim 44 wherein the substrate further comprises a semiconductor layer on an insulating substrate.

48. The apparatus of claim 44 wherein the plurality of ultrasonic transducers are piezoelectric.

49. The apparatus of claim 44 wherein the plurality of ultrasonic transducers comprise an array of transmitters.

50. The apparatus of claim 44 wherein the plurality of ultrasonic transducers further comprise at least one transmitter.

51. The apparatus of claim 44 wherein the means for bonding has a predetermined size that is small relative to an ultrasonic transducer.

52. The apparatus of claim 44 wherein the plurality of ultrasonic transducers further comprise a plurality of transmitters arranged in a predetermined pattern.

53. The apparatus of claim 52 wherein the predetermined pattern is selected from the group consisting of a rectangular pattern, a circular pattern, a reticulated pattern, a diagonal pattern, a grid pattern, a random pattern, a triangular pattern, a cross pattern and an oval pattern.

54. The apparatus of claim 52 wherein each of the plurality of transmitters are connected mechanically and electrically through a bump bond to a high voltage switch on a substrate.

55. The apparatus of claim 54 wherein the high voltage switch further comprises a DMOS transistor.

56. The apparatus of claim 54 wherein one or more of the high voltage switches may be electrically actuated to connect the complementary ultrasonic transducer to the common electrical ground.

57. The apparatus of claim 56 wherein the activation of the high voltage switches is controlled by a microcontroller.

58. The apparatus of claim 57 wherein the pattern of activation of each high voltage switch creates at least one group of transmitters from the plurality of transmitters.

59. The apparatus of claim 54 wherein a group of transmitters is selected by a high voltage switch and is driven sequentially through the common electrode.

60. The apparatus of claim 59 further comprising a signal processing means for combining image.

61. The apparatus of claim 54 wherein a DC voltage is applied to the common electrode end and a pattern of high voltage switches are connected to electrical ground by a short activation pulse or a series of activation pulses to create an ultrasonic transmitter pulse.

62. The apparatus of claim 54 wherein the common electrode is connected to electrical ground and a pattern of high voltage switches are connected to a DC voltage on the substrate by a short activation pulse or a series of activation pulses to create an ultrasonic transmitter pulse.

63. The apparatus of claim 44 further comprising an acoustic lens located in an acoustic medium or fluid between a source of ultrasonic energy of a predetermined wavelength and the plurality of ultrasonic transducers wherein the acoustic lens is constructed so as to provide a gradual transition from one medium or fluid to another.

64. The apparatus of claim 63 wherein the acoustic lens has a surface shaped as a binary concave lens.

65. The apparatus of claim 63 wherein the acoustic lens comprises a graded surface area having gradations less than the predetermined wavelength.

40. An apparatus for generating quasi incoherent ultrasonic insonification comprising:

(a) a first group of coherent transmitters; and

(b) a second group of coherent transmitters wherein the first group transmits a different ultrasonic signal from the second group.

41. The apparatus of claim 40 wherein the first group and the second group of coherent transmitters comprise an array of transmitters wherein members of each group are randomly distributed across the array.

42. The apparatus of claim 40 wherein a group transmits a pulse of ultrasonic energy.

43. The apparatus of claim 40 wherein a group transmits a gated sine wave of ultrasonic energy.

66. An apparatus for generating ultrasonic energy for an ultrasonic camera comprising:

(a) a plurality of ultrasonic transducers, each of the plurality of ultrasonic transducers having a common electrode end and an individually isolated driving layer end wherein each one of the plurality of ultrasonic transducers are divided into a plurality of subelements;

(b) a means for bump bonding each one of the plurality of ultrasonic transducers to a substrate; and

(c) a high voltage electrical conductor connected to at least one individually isolated driving layer end to provide a drive signal to at least one of the plurality of ultrasonic transducers to generate the ultrasonic energy.

67. The apparatus of claim 66 wherein the plurality of subelements are surrounded by epoxy.

68. The apparatus of claim 66 wherein the ultrasonic transducer has a first volume and the plurality of subelements have a second volume and the ratio of the second volume to the first volume is between 10% and 50%.

69. The apparatus of claim 66 wherein the number of subelements is four.

70. The apparatus of claim 66 wherein a predetermined mass is attached to the individually isolated driving layer.