Acoustical holography with multi-level square wave excitation signals

Patent metadata

Field	Value
Publication number	US-9639056-B2
Application number	US-201314029426-A
Country	US
Kind code	B2
Filing date	Sep 17, 2013
Priority date	Sep 17, 2013
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

Systems and methods are disclosed herein in which multi-level square wave excitation signals are used instead of or in addition to fully-analog excitation signals to drive an array of transceiver elements to create a sound field. Use of multi-level square wave excitation signals produces acceptable transceiver output with reduced complexity, cost, and/or power consumption as compared with use of fully-analog excitation signals. In addition, use of such signals facilitates system implementation using application-specific integrated circuits (ASICs) and is not as restricted in voltage level and speed. At the same time, the benefits and applications of fully-analog excitation signals (e.g., acoustic holography, beam superposition, signal-to-noise ratio (SNR) improvements, suppression of parasitic modes, increased material penetration, potential for coded pulsing algorithms and suppression of side lobes in ultrasonic field) can still be achieved with multi-level square wave excitation signals.

First claim

What is claimed is:

1. An ultrasonic holography system comprising:
an ultrasonic transducer array including:
a plurality of transmitter elements configured to emit a plurality of ultrasonic waveforms toward a physical item;
a plurality of receiver elements configured to receive a plurality of return ultrasonic waveforms reflected from the physical item; and
a processor system coupled to said ultrasonic transducer array, said processor system configured to:
determine an analog ultrasonic holography tone burst signal;
rectangular-step sample the analog ultrasonic holography tone burst signal to select a multi-level square wave tone burst signal;
generate a plurality of outgoing multi-level square wave transmitter driving signals configured to cause said ultrasonic transducer array to emit said plurality of ultrasonic waveforms, wherein each of said plurality of ultrasonic waveforms are differentiated from the multi-level square wave tone burst signal through variation of at least one of amplitude, frequency, phase, time shift, and a modulation of any one thereof;
receive a plurality of incoming analog waveform signals, generated by said ultrasonic transducer array, said incoming analog waveform signals representative of at least a portion of said plurality of return ultrasonic waveforms; and
process the plurality of incoming analog waveform signals to evaluate the internal structure of the physical item.

2. The system of claim 1 , wherein the plurality of transmitter elements and the plurality of receiver elements are formed as a plurality of common transceiver elements.

3. The system of claim 1 , wherein the processor system is configured to process the plurality of incoming analog waveform signals by constructing a virtual image using the plurality of incoming analog waveform signals, the virtual image corresponding to at least a portion of an internal region of the physical item.

4. The system of claim 1 , wherein at least two of said plurality of ultrasonic waveforms are differentiated from each other through variation of at least two of amplitude, frequency, phase, time shift, and a modulation of any one thereof.

5. The system of claim 1 , wherein the processor system includes a pulse generator circuit configured to produce said multi-level square wave transmitter driving signals.

6. The system of claim 1 , wherein the processor system is configured to generate multi-level square wave transmitter driving signals having a plurality of positive rectangular steps and a plurality of negative rectangular steps.

7. The system of claim 1 , wherein the processor system is configured to generate multi-level square wave transmitter driving signals with up to five discrete positive voltage levels, up to five discrete negative voltage levels, and up to one zero voltage level.

8. The system of claim 1 , wherein the processor system is configured to generate the plurality of multi-level square wave transmitter driving signals such that at least one of said signals is a rectangular-sampled approximation of a corresponding fully-analog driving signal.

9. The system of claim 8 , wherein the at least one signal includes a plurality of steps having amplitudes that correspond to amplitudes of counterpart peaks in the corresponding fully-analog driving signal.

10. The system of claim 9 , wherein the plurality of steps are selected from a finite set of discrete voltage levels.

11. The system of claim 10 , wherein, for each peak in the corresponding fully-analog driving signal, a step selected from the finite set that is closest in voltage to the peak is included in the at least one signal.

12. The system of claim 8 , wherein the at least one signal includes a plurality of steps having widths that correspond to widths between counterpart inflection points in the corresponding fully-analog driving signal.

13. The system of claim 8 , wherein transitions between steps in the at least one signal correspond in phase to counterpart inflection points in the corresponding fully-analog driving signal.

14. The system of claim 1 , wherein the plurality of multi-level square wave transmitter driving signals are selected by performing de-convolution of the pulse response of the transducer array from a desired ultrasonic waveform.

15. The system of claim 1 , wherein the processor system is configured to execute a holographic reconstruction algorithm using the plurality of incoming analog waveform signals.

16. A method for imaging a physical item using ultrasonic holographic imaging, comprising:
using a processor system coupled to a memory device;
defining an image structure using data stored in the memory device, the data representing a geometry of the physical item;
determine an analog ultrasonic holography tone burst signal;
rectangular-step sample the analog ultrasonic holography tone burst signal to select a multi-level square wave tone burst signal;
driving a plurality of ultrasonic transmitter elements of a transducer array coupled to the processor system with a plurality of multi-level square wave transmitter driving signals to cause the ultrasonic transducer array to emit a plurality of ultrasonic waveforms, wherein each of the of ultrasonic waveforms are differentiated from the multi-level square wave tone burst signal through variation of at least one of amplitude, frequency, phase, time shift, and a modulation of any one thereof.

17. The method of claim 16 , further comprising:
emitting into the physical item, with the ultrasonic transducer array, the plurality of ultrasonic waveforms;
receiving, with the ultrasonic transducer array, a plurality of ultrasonic waveforms reflected from the physical item; processing, with the processor system, the plurality of reflected ultrasonic waveforms to produce a plurality of digital A-Scans; and
evaluating, with the processor system, the plurality of digital A-scans.

18. The method of claim 16 , wherein at least two of the ultrasonic waveforms are differentiated from each other through variation of at least two of amplitude, frequency, phase, time shift, and a modulation of any one thereof.

19. The method of claim 16 , wherein the processor system includes a pulse generator circuit configured to produce said multi-level square wave transmitter driving signals.

20. The method of claim 16 , wherein said driving comprises generating multi-level square wave transmitter driving signals having a plurality of positive rectangular steps and a plurality of negative rectangular steps.

21. The method of claim 16 , wherein said driving comprises generating multi-level square wave transmitter driving signals with up to five discrete positive voltage levels, up to five discrete negative voltage levels, and up to one zero voltage level.

22. The method of claim 16 , wherein said driving comprises generating at least one signal that is a rectangular-sampled approximation of a corresponding fully-analog driving signal.

23. A system, comprising:
an ultrasonic transducer array including a plurality of transmitter elements configured to emit a plurality of ultrasonic waveforms;
a processor system coupled to said ultrasonic transducer array, said processor system configured to:
determine an analog ultrasonic holography tone burst signal;
rectangular-step sample the analog ultrasonic holography tone burst signal to select a multi-level square wave tone burst signal;

a pulse generation circuit configured to generate a plurality of multi-level

Assignees

• Gen Electric

Inventors

• Falter Stephan
• Barshinger James Norman
• Lange Dirk
• Feydo Mark Howard
• Lammerich Werner

Classifications

• G03H3/00 Primary

  Holographic processes or apparatus using ultrasonic, sonic or infrasonic waves for obtaining holograms; Processes or apparatus for obtaining an optical image from them (G03H1/22 takes precedence) · CPC title

• G01N29/348

  with frequency characteristics, e.g. single frequency signals, chirp signals (measuring frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04; measuring frequency or analysing frequency spectra G01R23/00) · CPC title

• G01S7/523

  Details of pulse systems {(short-range imaging G01S7/52017; methods or devices for transmitting, conducting or directing sound G10K11/18)} · CPC title

• G01N29/0663

  by acoustic holography (acoustical holography per se G03H3/00) · CPC title