Simultaneous firing scheme for acoustic inspection

Abstract

Acoustic evaluation of a target can be performed using an array of electroacoustic transducers. For example, a technique for such evaluation includes generating pulses for transmission by each of a plurality of electroacoustic transducers in a transducer array to simultaneously establish respective acoustic beams corresponding to at least two different acoustic beam steering directions for acquisition, the pulses including at least a first sequence having pulses defining a profile with a first polarity, the first sequence corresponding to a first beam steering direction (e.g., angular or spatial beam direction), and a second sequence having pulses defining a profile with a second polarity opposite the first polarity, the second sequence corresponding to a second beam steering direction. In response to the transmission of the pulses, respective acoustic echo signals can be received and aggregated to form an image of a region of interest on or within the target.

Description

[Technical field]

[0001] Claiming priority This patent application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 201,468 to Lepage et al., entitled “CONTEMPORANEOUS FIRING SCHEME FOR ACOUSTIC INSPECTION,” filed on April 30, 2021 (Attorney Docket No. 6409.194PRV), which is incorporated by reference in its entirety.

[0002] This document relates generally to non-destructive evaluation, and more specifically, but not exclusively, to apparatus and techniques for providing acoustic inspection using multiple simultaneously transmitted acoustic beams, such as those established using one- or two-dimensional transducer arrays. [Background technology]

[0003] Various inspection techniques may be used to image or otherwise analyze structures without damaging such structures. For example, one or more of x-ray inspection, eddy current inspection, or acoustic (e.g., ultrasonic) inspection may be used to acquire data for imaging features on or within the test sample. For example, acoustic imaging may be performed using an array of ultrasonic transducer elements, such as to image a region of interest within the test sample. Different imaging modes may be used to present received acoustic signals scattered or reflected by structures on or within the test sample.

[0004] For example, an amplitude or "A-scan" representation may include generating a plot or other display of the magnitude of the received ultrasonic signal versus time or depth, such as along a linear beam axis or ray that traverses the test sample. Beamforming may be performed using coherent excitation of the ultrasonic transducer to provide a desired beam angle and focal position. For example, the coherent excitation may include applying a specified delay value (or phase shift) to pulses for transmission by individual array elements (or apertures defined thereby) to establish either or both of the desired beam angle and focal position. Alternatively, or additionally, beamforming may be performed on receive, such as by summing received acoustic echo signals in a manner in which signals received from individual array elements are delayed (or phase shifted) to provide one or more of the desired beam angle and focal position. Summary of the Invention [Means for solving the problem]

[0005] Acoustic testing, such as ultrasound-based inspection, may include focusing or beamforming techniques to aid in constructing a data plot or image representative of a region of interest within a test sample. The use of an array of ultrasonic transducer elements may include the use of a phased array beamforming approach and may be referred to as phased array ultrasonic testing (PAUT). For example, a delay-and-sum beamforming technique may be used, which includes coherently summing a time-domain representation of the received acoustic signal from each transducer element or aperture.

[0006] The inventors have recognized that the use of multiple (e.g., two or more) simultaneously established acoustic beams can improve acoustic inspection throughput, such as by enabling acoustic interrogation (e.g., scanning) of a larger spatial range for each acquisition compared to using a single beam approach across multiple acquisitions. However, the use of such simultaneously established beams (as may be referred to as "co-firing") may present various challenges. For example, the acoustic pressure fields corresponding to each beam may overlap at or near the central axis or central region of the transmit acoustic probe array. Such overlap may occur when the firing angles are close to each other or when the count of firing angles is increased. The acoustic pressure field may also include undesirable off-axis features, such as side lobes.

[0007] In one approach, time reversal techniques can be used for transmit pulse synthesis, which is established as a sequence of square pulses with the same polarity. Simulations show that the temporal and spatial overlap of pulses with the same polarity can result in launch beams containing acoustic components that interfere with each other in an undesirable manner. In general, in the technique used for synthesis, the unmodified individual transmit excitation pulse sequences of each beam direction are simply superimposed on each other without adjustment, and if each of the pulses has the same polarity, the simultaneously launched beams may be unclear in direction or spatial extent or otherwise not properly controlled.

[0008] To address such challenges, the inventors have also recognized that establishing the pulse profile of each simultaneously generated beam in a manner with alternating or otherwise controlled pulse polarity can combat inter-beam interference, including modifying or adjusting the pulse sequence, using an approach similar to the time-reversal approach. For example, the polarity of each pulse used in one sequence can be inverted relative to the respective polarity in the sequence used to generate the spatially adjacent beam. The use of such "alternating" polarity can result in reduction or cancellation of pulse amplitudes in a manner that mitigates the required amplitude level count or the dynamic range of the transmit driver, or both. Such an approach can provide simultaneously generated beams that each more closely resemble an acoustic pressure field profile corresponding to a reference profile that includes a single beam. The approach described herein can also facilitate the use of simpler driver circuitry compared to other approaches, since the pulse amplitudes are relatively low and fewer amplitude levels can be used.

[0009] In one example, acoustic assessment of a target can be performed using an array of electroacoustic transducers, such as a one-dimensional (e.g., linear) or two-dimensional (e.g., matrix) array. For example, a technique for such assessment includes generating pulses for transmission by each of a plurality of electroacoustic transducers in a transducer array to simultaneously establish respective acoustic beams corresponding to at least two different acoustic beam steering directions for acquisition, the pulses including at least a first sequence having pulses defining a profile with a first polarity, the first sequence corresponding to a first beam steering direction, and a second sequence having pulses defining a profile with a second polarity opposite the first polarity, the second sequence corresponding to a second beam steering direction. In response to the transmission of the pulses, respective acoustic echo signals can be received and aggregated to form an image of a region of interest on or within the target. For example, the first sequence and the second sequence can define respective pulse sequences for different ones of a plurality of electroacoustic transducers, each pulse sequence including a sum of contributions from the first sequence and the second sequence corresponding to each of the plurality of electroacoustic transducers. The generation of pulses for transmission may include suppressing side lobe or beam formation in a direction perpendicular to the surface of the target.

[0010] As an illustrative example, a system for acoustic evaluation of a target may include an analog front end including transmit / receive circuitry coupled to a plurality of electroacoustic transducer elements; a processor circuit communicatively coupled to the analog front end; and a memory circuit including instructions that, when executed by the processor circuit, cause the system to perform the acoustic evaluation, e.g., generate pulses for transmission by each of a plurality of electroacoustic transducers in a transducer array to simultaneously establish respective acoustic beams corresponding to at least two different acoustic beam steering directions for acquisition, the pulses including at least a first sequence having pulses defining a profile having a first polarity, the first sequence corresponding to the first beam steering direction, and a second sequence having pulses defining a profile having a second polarity opposite the first polarity, the second sequence corresponding to the second beam steering direction; and receive respective acoustic echo signals in response to transmission of the pulses and aggregate the received acoustic echo signals to form an image of a region of interest on or within the target.

[0011] This Summary is intended to provide an overview of the subject matter of this patent application. It is not intended to provide an exclusive or exhaustive description of the invention. The Detailed Description is included to provide further information regarding this patent application.

[0012] In the drawings, which are not necessarily drawn to scale, like numerals may describe like components in different drawings. Like numerals with different letter suffixes may represent different instances of similar components. The drawings generally illustrate by way of example, but not by way of limitation, various embodiments discussed in the present document. [Brief description of the drawings]

[0013] [Figure 1]An example is generally shown that includes an acoustic inspection system, such as may be used to implement at least a portion of one or more of the techniques as shown and described herein. [Figure 2ABC] 2A, 2B, and 2C show illustrative examples of simulated single-beam acoustic pressure fields corresponding to different steering angles, as produced by a linear array driven to provide a single beam direction. [Figure 2D] 2B shows an illustrative example of pulse timing for each element or transmit aperture in a linear array corresponding to each of the simulated single beam acoustic pressure fields of FIG. 2A. [Figure 2E] 2C shows an illustrative example of pulse timing for each element or transmit aperture in a linear array corresponding to each of the simulated single beam acoustic pressure fields of FIG. 2B. [Figure 2F] 2D shows an illustrative example of pulse timing for each element or transmit aperture in a linear array corresponding to each of the simulated single beam acoustic pressure fields of FIG. 2C. [Figure 3A] Illustrative examples of acoustic pressure fields corresponding to different pulse sequences established using a time reversal approach are shown, showing that the beam orientation is not well defined by comparison with the individual steering beams of Figures 2A, 2B, and 2C. [Figure 3B] Illustrative examples of acoustic pressure fields corresponding to different pulse sequences established using a time reversal approach are shown, showing that the beam orientation is not well defined by comparison with the individual steering beams of Figures 2A, 2B, and 2C. [Figure 3C] 3B shows an illustrative example of pulse timing for each element or transmit aperture in a linear array corresponding to each of the simulated acoustic pressure fields of FIG. 3A. [Figure 3D] 3C shows an illustrative example of pulse timing for each element or transmit aperture in a linear array corresponding to each of the simulated acoustic pressure fields of FIG. 3B. [Figure 4A]1 shows illustrative examples of acoustic pressure fields corresponding to different pulse sequences established in accordance with the present subject matter, where the polarity of each pulse or pulse profile alternates for adjacent steering angles or beam positions. [Figure 4B] 1 shows illustrative examples of acoustic pressure fields corresponding to different pulse sequences established in accordance with the present subject matter, where the polarity of each pulse or pulse profile alternates for adjacent steering angles or beam positions. [Figure 4C] 4B shows an illustrative example of pulse timing for each element or transmit aperture of a linear array corresponding to each of the simulated acoustic pressure fields of FIG. 4A, with the arrows indicating alternating polarity pulses corresponding to each beam (e.g., the polarity of each pulse or pulse profile alternates for adjacent steering angles or beam positions). [Figure 4D] Illustrative examples of pulse timing for each element or transmit aperture of a linear array corresponding to each of the simulated acoustic pressure fields of FIG. 4B are shown, with arrows indicating alternating polarity pulses corresponding to each beam (e.g., the polarity of each pulse or pulse profile alternates for adjacent steering angles or beam positions). [Figure 5A] An illustrative example of a two-dimensional array representation (eg, a "matrix probe") is shown, in which techniques similar to the examples of Figures 4A, 4B, 4C, and 4D can be extended to two-dimensional array applications. [Figure 5B] Illustrative examples of acoustic beam directions are shown, where the acoustic beams extend at least partially radially in a circular configuration about the central axis of the two-dimensional array, with respective pulse profile polarities indicated by "+" or "-" symbols. [Figure 6A] 5B shows an illustrative example including pulse sequences and corresponding amplitudes for each element of a 64 element array, such as the 2D array shown in FIG. 5A, having a pulse profile corresponding to the profile polarity illustratively shown in FIG. 5B. [Figure 6B]An illustrative example is shown including a pulse sequence of an individual transducer element (or transducer aperture) according to the scheme shown in FIG. 6A. [Figure 7A] An illustrative example is shown including an acoustic pressure field in a cross section of the Z plane (according to the coordinate system illustratively shown in FIG. 5A ) established using the pulse sequence of FIG. 6A (e.g., first transmit set), showing different acoustic beam directions, where the acoustic beams extend at least partially radially in a circular configuration centered on the central axis of the two-dimensional array. [Figure 7B] 7A shows an illustrative example including an acoustic pressure field in a cross section in the xz plane (according to the coordinate system illustratively shown in FIG. 5A) and shows different acoustic beam directions in FIG. 7A from another perspective. [Figure 7C] An illustrative example is shown including an acoustic pressure field in a cross section of the z-plane (according to the coordinate system illustratively shown in FIG. 5A ), where acoustic beams are established using a different set of transmit sequences (e.g., a second transmit set) to establish another set of acoustic beams located in the “gaps” between the established acoustic beams, as shown in FIG. 7A , using the pulse sequence of FIG. 6A . [Figure 8] SUMMARY OF THE DISCLOSURE Techniques such as methods for operating an acoustic inspection system are generally presented. [Figure 9] 1 illustrates an example block diagram comprising a machine upon which any one or more of the techniques (eg, methodologies) discussed herein may be executed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present subject matter relates to devices and techniques that facilitate high throughput acoustic inspection, such as enabling simultaneous generation of multiple acoustic beams in a simultaneous manner. Such a scheme can be referred to as "co-firing", even though each element of the acoustic array need not all be literally transmitted at the same time. The simultaneous generation of multiple beams can include generating a sequence of pulses directed to each acoustic transducer (or corresponding group of transducers defining each transmit aperture) to generate an acoustic signal that, when aggregated with the transmissions from each other, results in an acoustic pressure field having two or more coherent acoustic beams extending in different designated directions. The inventors recognize that, among other things, for pulse sequences used for simultaneous transmission (as compared reception), the generated pulses associated with each beam may overlap in time within elements around the center of the transmit array, such as when the generated beam angles are close to each other or when there are many beams being generated simultaneously. The inventors also recognize that reducing distortion due to pulse overlap can help reduce the deviation of each beam from a reference profile corresponding to a single (non-simultaneous) beam, where that reference profile is transmitted alone. Examples herein show one-dimensional (eg, linear) and two-dimensional (eg, matrix) array implementations, as well as examples of pulse sequences that can be used to provide multiple beam directions simultaneously.

[0015] FIG. 1 generally illustrates an example including an acoustic inspection system 100, such as may be used to implement at least a portion of one or more of the techniques shown and described herein. The acoustic inspection system 100 may include a test instrument 140, such as a handheld or portable assembly. The test instrument 140 may be electrically coupled to a probe assembly, such as using a multi-conductor interconnect 130. The probe assembly 150 may include one or more electroacoustic transducers, such as a transducer array 152 including respective transducers 154A to 154N. The transducer array may follow a linear or curved contour, or may include an array of elements extending in two axes, such as providing a matrix of transducer elements. The elements need not be square in footprint, nor be arranged along a linear axis. The size and pitch of the elements may vary depending on the inspection application.

[0016] A modular probe assembly 150 configuration may be used that allows the test instrument 140 to be used with a variety of different probe assemblies 150. In general, the transducer array 152 includes, for example, a piezoelectric transducer that may be acoustically coupled to a target 158 ​​(e.g., a test sample or "object under test") via a coupling medium 156. The coupling medium may include a fluid or gel, or a solid membrane (e.g., an elastomer or other polymeric material), or a combination of fluids, gels, or solid structures. For example, an acoustic transducer assembly may include a transducer array coupled to a wedge structure that includes a rigid thermosetting polymer with known acoustic propagation properties (e.g., Rexolite® available from C-Lec Plastics Inc.), and water may be injected between the wedge and the structure under test as the coupling medium 156 during testing, or testing may be performed with the interface between the probe assembly 150 and the target 158 ​​or otherwise immersed in the coupling medium.

[0017] The test instrument 140 may include digital and analog electrical circuitry, such as a front-end circuit 122 that includes one or more transmit signal chains, receive signal chains, or switching circuitry (e.g., transmit / receive switching circuitry). The transmit signal chain may include amplifier and filter circuitry to provide transmit pulses for delivery to the probe assembly 150 via the interconnect 130 for ultrasonic irradiation of the target 158, and to image or otherwise detect defects 160 on or within the target 158 ​​structure by receiving scattered or reflected acoustic energy elicited in response to the ultrasonic irradiation.

[0018] 1 shows a single probe assembly 150 and a single transducer array 152, other configurations can be used, such as multiple probe assemblies connected to a single test fixture 140, or multiple transducer arrays 152 used with single or multiple probe assemblies 150 for pitch / catch inspection. Similarly, a test protocol can be performed using coordination between multiple test fixtures 140, for example, in response to an overall test scheme established from a master test fixture 140, or established by another remote system such as computing facility 108 or a general purpose computing device such as a laptop 132, tablet, smartphone, desktop computer, etc. The test scheme can be established according to published standards or regulatory requirements, and can be repeatedly performed, as illustrative examples, at initial production or for ongoing monitoring.

[0019] The receive signal chain of the front-end circuitry 122 may include one or more filter or amplifier circuits along with analog-to-digital conversion facilities to digitize echo signals received using the probe assembly 150. The digitization may be performed coherently to provide multiple channels of digitized data that are aligned or referenced to one another in time or phase. The front-end circuitry may be coupled to and controlled by one or more processor circuits, such as the processor circuit 102 included as part of the test instrument 140. The processor circuit may be coupled to a memory circuit, for example, to execute instructions that cause the test instrument 140 to perform one or more of acoustic transmission, acoustic acquisition, processing, or storage of data associated with an acoustic test, or otherwise perform techniques as shown and described herein. The test instrument 140 may be communicatively coupled to other portions of the system 100, such as using a wired or wireless communication interface 120.

[0020] For example, performance of one or more techniques as shown and described herein may be accomplished on the test instrument 140 or using other processing or storage facilities, such as using the computing facilities 108 or general purpose computing devices such as laptops 132, tablets, smartphones, desktop computers, etc. For example, processing tasks that would be unnecessarily slow if performed on the test instrument 140 or run beyond the capabilities of the test instrument 140 may be performed remotely (e.g., on a separate system), e.g., in response to a request from the test instrument 140. Similarly, storage of intermediate data, e.g., A-scan matrices of imaging data or time series data, or other representations of such data, may be accomplished using remote facilities communicatively coupled to the test instrument 140. The test instrument may include a display 110, such as for presentation of configuration information or results, and an input device 112, including one or more of a keyboard, trackball, function or soft keys, mouse interface, touch screen, stylus, etc., for receiving operator commands, configuration information, or responses to queries.

[0021] 2A, 2B, and 2C show illustrative examples of simulated single-beam acoustic pressure fields corresponding to different steering angles. FIG. 2A shows a steering angle of +6 degrees, FIG. 2B shows a steering angle of +12 degrees, and FIG. 2C shows a steering angle of +18 degrees. The acoustic fields of FIG. 2A, 2B, and 2C may be generated by a linear array driven to provide a single beam direction. Such examples may be considered as "reference" representations corresponding to single-angle or single-direction acoustic beamforming. A single unit pulse amplitude is used (e.g., only two pulse amplitude levels are used: zero units and one unit). In general, the techniques shown and described herein may be used to provide simultaneous generation of multiple beams that approximate the pressure field of the corresponding single-beam reference field. FIG. 2D, 2E, and 2F show illustrative examples of pulse timing of each element or transmit aperture in a linear array corresponding to each of the simulated single-beam acoustic pressure fields of FIG. 2A, 2B, and 2C.

[0022] 3A and 3B show illustrative examples of acoustic pressure fields corresponding to different pulse sequences established using a time reversal approach, showing that for simulated parameters, the beam orientation is not well defined by comparison with the individual steering beams of FIG. 2A, FIG. 2B, and FIG. 2C. FIG. 3C and FIG. 3D show illustrative examples of pulse timing of each element or transmit aperture of a linear array corresponding to each of the simulated acoustic pressure fields of FIG. 3A and FIG. 3B. For example, FIG. 3A shows simultaneous firing of steering angles of +6 degrees, +12 degrees, and +18 degrees (combining the individual beams of FIG. 2A, FIG. 2B, and FIG. 2C), and FIG. 3C shows the corresponding pulse timing. FIG. 3B shows simultaneous firing of steering angles of −18, −12, −6, +6, +12, and +18 degrees (combining the individual beams of FIG. 2A, FIG. 2B, and FIG. 2C and adding their “mirror” angles). FIG. 3D shows the corresponding pulse timing for generating the acoustic pressure field of FIG. 3B. The maximum pulse amplitude used in the schemes shown in Figures 3C and 3D is generally equal to the count of different co-established beams, such as +3 units for Figure 3C (corresponding to three beam directions) and +6 units for Figure 3D (corresponding to six beam directions). As indicated by the arrows, all pulses are positive relative to the baseline (e.g., all pulses are of the same polarity). Although the acoustic pressure field exhibits some degree of directionality, the individual beams at angles of 6 degrees, 12 degrees, and 18 degrees relative to the central axis shown perpendicular at the zero millimeter position are not well defined relative to each other, as compared to the alternating polarity example below.

[0023] 4A and 4B show illustrative examples of acoustic pressure fields corresponding to different pulse sequences established in accordance with the present subject matter, where the polarity of each pulse or pulse profile alternates for adjacent steering angles or beam positions. The acoustic array geometry and transmit parameters are otherwise the same as the above example of FIG. 3A. FIG. 4C and 4D show illustrative examples of pulse timing for each element or transmit aperture of a linear array corresponding to each of the simulated acoustic pressure fields of FIG. 4A and 4B, with the arrows indicating alternating polarity pulses corresponding to each beam (e.g., the polarity of each pulse or pulse profile alternates for adjacent steering angles or beam positions). The various illustrative examples above show underwater acoustic fields simulated using a two-dimensional model. The probe geometry includes a linear array with 11 elements and uses a wavelet corresponding to each pulse, where the wavelet has a frequency of 3.5 megahertz (MHz) and a bandwidth of 70%. The transducer element pitch is 0.75 millimeters, and the focal length is modeled as infinite for these examples. The approach illustrated in Figures 4C and 4D can generally correspond to the sequence of Figure 3C, but by inverting the polarity of the pulses of each adjacent beam angle. For example, the sequence of Figure 2D can be combined with the sequence of Figure 2F, as well as the reverse polarity representation of the sequence of Figure 2E (e.g., the pulse profiles of each element in each beam direction are linearly summed together). The resulting sequence is illustrated in Figure 4C. A "mirror" beam angle sequence can be added to provide a six-beam transmission using the pulse sequence illustrated in Figure 4D.

[0024] The approaches of Figures 4A, 4B, 4C, and 4D may present challenges at small symmetric angles or zero degree angles, for example, because the central element may be at zero amplitude as shown in 450A or 450B. This challenge may be addressed by using a multi-shot approach, such as including three acquisitions, where positive angles are fired simultaneously during one acquisition and negative angles are fired simultaneously during another acquisition, with a zero angle acquisition (e.g., normally incident on the target surface) being performed separately using yet another acquisition if required for the spatial or directional coverage specified by the application. Such sequences of different beam groups are also applicable to examples using two-dimensional (e.g., matrix) arrays, as discussed below.

[0025] In general, the approach of Figures 4A, 4B, 4C, and 4D provides improved control of beam orientation of linear phased arrays, resulting in better angular resolution, and similar schemes are applicable to two-dimensional (e.g., matrix) array configurations, as discussed below. The drive circuitry may be simplified compared to other approaches because the pulse amplitudes are relatively low and fewer amplitude levels may be used. For example, the approach shown in Figures 4C and 4D uses only three levels, including +1 unit, -1 unit, and zero unit, where the units correspond to a specified amplitude value, such as the magnitude of the full available output that may be generated by the transmit drive circuitry). The use of single-unit positive or negative going pulse sequences allows the use of this simultaneous firing scheme with legacy transmit hardware, where multiple positive or negative amplitude levels (other than single unit) may not be supported.

[0026] FIG. 5A shows an illustrative example of a two-dimensional array representation (e.g., a "matrix probe") in which techniques similar to those in the examples of FIGS. 4A, 4B, 4C, and 4D can be extended to two-dimensional array applications. FIG. 5B shows an illustrative example of acoustic beam orientations, where the acoustic beams extend at least partially radially in a circular configuration about a central axis of the two-dimensional array, with respective pulse profile polarities indicated by "+" or "-" symbols. Applications for such arrangements of radially extending beams can include rotating tube inspection systems (RTIS). RTIS can include inspection for oblique defects or notches in all orientations (e.g., 0 degrees to 360 degrees), such as for compliance with regulatory requirements or standards where such inspection must achieve coverage of all defect orientations (e.g., not parallel or transverse to the long axis of the tubular structure). When using pulse-echo inspection, multiple directional ultrasonic beams are transmitted in succession, without simultaneous firing, using a linear or matrix array disposed on the exterior surface of the tubular object under test to cover oblique defects from 0 degrees to 360 degrees. The approach described herein allows multiple beams to be generated simultaneously, such as to increase inspection throughput, including suppressing or completely eliminating the generation of undesirable side lobes. For example, the technique can be used for simultaneous firing, including suppressing or completely eliminating side lobes of the normal incidence direction on the tubular object under test.

[0027] FIG. 6A shows an illustrative example including a pulse sequence and corresponding amplitude for each element in a 64-element array such as a 2D array as shown in FIG. 5A with a pulse profile corresponding to the profile polarity illustrated in FIG. 5B, and FIG. 6B shows an illustrative example including a pulse sequence for each transducer element (or transducer aperture) according to the scheme illustrated in FIG. 6A. FIG. 7A shows an illustrative example including an acoustic pressure field in a cross section of the Z plane (according to the coordinate system illustrated in FIG. 5A) established using the pulse sequence (e.g., the first transmit set) of FIG. 6A, showing different acoustic beam directions, where the acoustic beam extends at least partially radially in a circular configuration centered on the central axis of the two-dimensional array. FIG. 7B shows an illustrative example including an acoustic pressure field in a cross section of the xz plane (according to the coordinate system illustrated in FIG. 5A), showing the different acoustic beam directions of FIG. 7A from another perspective. The pressure fields of Figures 7A and 7B can be used for a first acquisition corresponding to a first set of pulse sequences defining a first group of beams.

[0028] FIG. 7C shows an illustrative example including an acoustic pressure field in a cross section of the z-plane (according to the coordinate system illustratively shown in FIG. 5A), where acoustic beams are established using a different set of transmit sequences (e.g., a second transmit set) to establish another set of acoustic beams located in the "gaps" between the established acoustic beams, as shown in FIG. 7A, using the pulse sequence of FIG. 6A.

[0029] By way of illustration, the approach shown in FIG. 7A or FIG. 7C (or a combination including two acquisitions using the field profile of FIG. 7A in a first transmit set and the field profile of FIG. 7C in a second transmit set) can be used for detection of oblique defects or notches having orientations from 0 degrees to 360 degrees for various applications such as a rotating tube inspection system (RTIS), as described above.

[0030] As mentioned above, in the absence of the present subject matter, complex drive circuits or the generation of possible undesirable side lobes (e.g., normal to the beam) may occur in applications where multiple beam directions are transmitted simultaneously, especially as the frequency increases. In contrast, using an approach as illustratively shown in FIG. 7A or FIG. 7C (or both in a sequence of two or more acquisitions), such as having pulse profile polarities arranged as illustratively shown in FIG. 5B, can provide two or more acoustic beams oriented in specified directions. Such an approach can be achieved with reduced drive complexity. For example, as shown in FIG. 6A, five amplitude levels can be used, such as positive full unit (+2), half full unit (+1), zero (0), negative half full unit (-1), and negative full unit (-2). Other beam configurations are possible, and the spatial configurations shown in FIG. 7A, FIG. 7B, and FIG. 7C are merely exemplary. In general, the count of pulse levels (including the zero amplitude level) can be less than the count of pulses in the sequence. Simulations for Figures 7A, 7B, and 7C were prepared using FIELD II, available from Jorgen Arendt Jensen, Denmark, http: / / field-ii.dk / / .

[0031] 8 generally illustrates a technique 800, such as a method, for operating an acoustic inspection system, including generating pulses for transmission by each of a plurality of electroacoustic transducers in a transducer array to simultaneously establish respective acoustic beams corresponding to at least two different acoustic beam steering directions for acquisition at 820. Generating pulses includes generating a first sequence having pulses defining a profile with a first polarity, the first sequence corresponding to the first beam steering direction, and generating pulses includes generating a second sequence having pulses defining a profile with a second polarity opposite the first polarity, the second sequence corresponding to the second beam steering direction at 830. In response to transmitting the pulses, respective acoustic echo signals can be received and aggregated (e.g., coherently summed) at 835 to form an image of a region of interest on or within the target.

[0032] 9 illustrates an example block diagram of a machine 900 on which any one or more of the techniques (e.g., methodologies) discussed herein may be executed. The machine 900 (e.g., a computer system) may include a hardware processor 902 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memory 904, and a static memory 906, which are connected via an interconnect 908 (e.g., a link or bus), and some or all of these components may constitute hardware for the systems and related implementations discussed above.

[0033] Specific examples of main memory 604 include semiconductor memory devices that may include storage locations in a semiconductor, such as Random Access Memory (RAM) and registers. Specific examples of static memory 906 include non-volatile memory, such as semiconductor memory devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM)) and flash memory devices, magnetic disks, such as internal hard disks and removable disks, magneto-optical disks, RAM, or optical media, such as CD-ROM and DVD-ROM disks.

[0034] The machine 900 may further include a display device 910, an input device 912 (e.g., a keyboard), and a user interface (UI) navigation device 914 (e.g., a mouse). In one example, the display device 910, the input device 912, and the UI navigation device 914 may be touch screen displays. The machine 900 may further include a mass storage device (e.g., a drive unit) 916, a signal generating device 918 (e.g., a speaker), a network interface device 920, and one or more sensors 930, such as a global positioning system (GPS) sensor, a compass, an accelerometer, or other sensors. The machine 900 may include an output controller 928, such as a serial (e.g., universal serial bus (USB), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC), etc.) connection, for communicating with or controlling one or more peripheral devices (e.g., a printer, a card reader, etc.).

[0035] The mass storage device 916 may include a machine-readable medium 922 on which is stored one or more sets of data structures or instructions 924 (e.g., software) that embody or are utilized by any one or more of the techniques or functions described herein. The instructions 924 may also reside, completely or at least partially, within the main memory 904, within the static memory 906, or within the hardware processor 902 during execution thereof by the machine 900. In one example, one or any combination of the hardware processor 902, the main memory 904, the static memory 906, or the mass storage device 916 comprises a machine-readable medium.

[0036] Specific examples of machine-readable media include one or more of non-volatile memory, such as semiconductor memory devices (e.g., EPROM or EEPROM) and flash memory devices, magnetic disks, such as internal hard disks and removable disks, magneto-optical disks, RAM, or optical media, such as CD-ROM and DVD-ROM disks. Although machine-readable medium 922 is illustrated as a single medium, the term "machine-readable medium" may include a single medium or multiple media (e.g., a centralized or distributed database, or associated caches and servers) configured to store one or more instructions 924.

[0037] The apparatus of the machine 900 includes one or more of a hardware processor 902 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memory 904 and static memory 906, a sensor 930, a network interface device 920, an antenna 932, a display device 910, an input device 912, a UI navigation device 914, a mass storage device 916, an instruction device 924, a signal generation device 918, or an output controller 928. The apparatus may be configured to perform one or more of the methods or operations disclosed herein.

[0038] The term "machine-readable medium" may include any medium capable of storing, encoding, or carrying instructions for execution by the machine 900, causing the machine 900 to perform any one or more of the techniques of this disclosure, or causing another device or system to perform any one or more of the techniques, or capable of storing, encoding, or carrying data structures used by or associated with such instructions. Non-limiting examples of machine-readable media may include solid-state memory, and optical or magnetic media. Specific examples of machine-readable media include non-volatile memory, such as semiconductor memory devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM)) and flash memory devices, magnetic disks, such as internal hard disks and removable disks, magneto-optical disks, random access memory (RAM), or optical media, such as CD-ROM disks and DVD-ROM disks. In some embodiments, the machine-readable medium includes a non-transitory machine-readable medium. In some embodiments, the machine-readable medium includes a machine-readable medium that is not a transitory propagating signal.

[0039] The instructions 924 may be transmitted or received over a communications network 926 using a transmission medium via the network interface device 920, for example, utilizing any one of a number of transport protocols (e.g., Frame Relay, Internet Protocol (IP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Hypertext Transfer Protocol (HTTP), etc.). Exemplary communication networks include local area networks (LANs), wide area networks (WANs), packet data networks (e.g., the Internet), mobile telephone networks (e.g., cellular networks), Plain Old Telephone (POTS) networks, and wireless data networks (e.g., the Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards known as Wi-Fi®), the IEEE 802.15.4 family of standards, the Long Term Evolution (LTE) 4G or 5G family of standards, the Universal Mobile Telecommunications System (UMTS) family of standards, peer-to-peer (P2P) networks, and satellite networks, among others.

[0040] In one example, the network interface device 920 may include one or more physical jacks (e.g., Ethernet, coaxial, or interconnect) or one or more antennas for accessing the communications network 926. In one example, the network interface device 920 may include one or more antennas 932 that communicate wirelessly using at least one of single-input multiple-output (SIMO), multiple-input multiple-output (MIMO), or multiple-input single-output (MISO) technologies. In some embodiments, the network interface device 920 communicates wirelessly using multi-user MIMO technology. The term "transmission medium" should be understood to include any intangible medium capable of storing, encoding, or carrying instructions for execution by the machine 900, including digital or analog communications signals or other intangible media for facilitating the communication of such software.

[0041] Various notes The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are also commonly referred to as "examples." Such examples may include elements in addition to those shown or described. However, the inventors also contemplate examples in which only those elements shown or described are provided. Furthermore, the inventors also contemplate examples that use any combination or permutation of those elements (or one or more aspects thereof) shown or described with respect to a particular example (or one or more aspects thereof) or with respect to other examples (or one or more aspects thereof) shown or described herein.

[0042] In the event of a conflict of usage between this document and any document so incorporated by reference, the usage in this document shall control.

[0043] In this document, the terms "a" or "an" are used to include one or more, as is common in patent documents, regardless of any other instance or usage of "at least one" or "one or more." In this document, the term "or" is used to refer to a non-exclusive or, such that "A or B" includes "A but not B," "B but not A," and "A and B," unless otherwise indicated. In this document, the terms "including" and "in which" are used as the plain English equivalents of the terms "comprising" and "wherein," respectively. Also, in the following claims, the terms "including" and "comprising" are open-ended, i.e., a system, device, article, composition, formulation, or process that includes elements in addition to those recited after such term in a claim is still considered to be within the scope of that claim. Moreover, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels and are not intended to impose numerical requirements on their objects.

[0044] The method embodiments described herein may be at least partially implemented by a machine or computer. Some examples may include a computer-readable medium or machine-readable medium encoded with instructions operable to configure an electronic device to perform the methods described in the above examples. Implementations of such methods may include code, such as microcode, assembly language code, higher level language code, etc. Such code may include computer-readable instructions for performing various methods. Code may form part of a computer program product. Such instructions may be read and executed by one or more processors, for example to enable the execution of operations including the methods. The instructions may be in any suitable form, such as, but not limited to, source code, compiled code, interpreted code, executable code, static code, dynamic code, etc.

[0045] Further, in one example, the code may be tangibly stored, such as during execution or at other times, on one or more volatile, non-transitory, or non-volatile tangible computer readable media. Examples of these tangible computer readable media may include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memory (RAM), read-only memory (ROM), etc.

[0046] The above description is intended to be illustrative and not limiting. For example, the examples described above (or one or more aspects thereof) may be used in combination with each other. Other embodiments may be used, for example, by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to enable the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be construed as intending that an unclaimed disclosed feature is essential to any claim. Rather, the subject matter of the invention may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are incorporated into the Detailed Description as an example or embodiment, with each claim standing alone as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. 1. A method for acoustic assessment of a target using an array of electroacoustic transducers, comprising: generating a pulse for transmission by each of a plurality of electroacoustic transducers in a transducer array to simultaneously establish respective acoustic beams corresponding to at least two different acoustic beam steering directions for acquisition, the pulse comprising at least a first sequence having pulses defining a profile having a first polarity, the first sequence corresponding to a first beam steering direction; generating a second sequence having pulses defining a profile having a second polarity opposite to the first polarity, the second sequence corresponding to a second beam steering direction; receiving respective acoustic echo signals in response to transmitting the pulses, and aggregating the received acoustic echo signals to form an image of a region of interest on or within the target.

2. 2. The method of claim 1 , wherein generating the pulses includes generating respective sequences for different ones of the plurality of electroacoustic transducers and includes suppressing generation of pulses for a central element or aperture defined by the transducer array.

3. the first sequence and the second sequence define respective pulse sequences for different ones of the plurality of electroacoustic transducers; The method of claim 1 or 2, wherein each of the pulse sequences comprises a sum of contributions from the first sequence and the second sequence corresponding to each of the plurality of electroacoustic transducers.

4. The method of claim 1 or 2, wherein the array comprises a one-dimensional array.

5. The method described in claim 3, wherein the amplitude of the pulses in each pulse sequence is at most a single unit amplitude.

6. The method of claim 1 or 2, wherein the array comprises a two-dimensional array.

7. generating pulses for transmission by each of the plurality of electroacoustic transducers in the two-dimensional array includes simultaneously establishing respective acoustic beams corresponding to a plurality of acoustic beam directions for the acquisition; The method of claim 6 , wherein the acoustic beams extend at least partially radially in a semicircular or circular configuration about a central axis of the two-dimensional array.

8. The method of claim 7 , wherein the first and second sequences correspond to adjacent acoustic beams in the semicircular or circular configuration about the central axis of the two-dimensional array.

9. The method of claim 3, wherein any amplitude of a pulse in each of the pulse sequences includes half unit amplitude, full unit amplitude, or zero amplitude.

10. The method of claim 3, wherein the amplitude of each pulse in each of the pulse sequences is established using a count level that is lower than the count of pulses in the sequence.

11. The method of claim 1 or 2, wherein generating the pulses for transmission includes suppressing side lobe or beam formation in a direction perpendicular to a surface of the target.

12. 3. The method of claim 1 or 2, wherein the first sequence and the second sequence are included as a first transmit set defining a first group of beams corresponding to a first acquisition, the method including generating respective sequences including a second transmit set defining a different second group of beams corresponding to a second acquisition.

13. The method of claim 12 , wherein the second group of beams defines beam directions that lie in gaps between respective beam directions of the first group of beams.

14. 1. An ultrasonic inspection system for acoustic evaluation of a target, comprising: an analog front end including a transmit / receive circuit coupled to a plurality of electroacoustic transducer elements; a processor circuit communicatively coupled to the analog front end; a memory circuit containing instructions; The instructions, when executed by the processor circuit, cause the ultrasound inspection system to perform the method of claim 1 or 2.

15. 1. An ultrasonic inspection system for acoustic evaluation of a target, comprising: means for generating pulses for transmission by each of a plurality of electroacoustic transducers in a transducer array to simultaneously establish respective acoustic beams corresponding to at least two different acoustic beam steering directions for acquisition, the pulses comprising at least a first sequence having pulses defining a profile having a first polarity, the first sequence corresponding to a first beam steering direction; a second sequence having pulses defining a profile having a second polarity opposite to the first polarity, the second sequence corresponding to a second beam steering direction; means for receiving respective acoustic echo signals in response to transmission of said pulses; and means for consolidating the received acoustic echo signals to form an image of a region of interest on or within the target.

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