Ultrasound transducer array with selectively coupled reference electrodes

Abstract

A method and apparatus for ultrasonic testing of manufactured parts using an ultrasound transducer array with selective electrode switching is disclosed. The system employs a divided common electrode for selecting subsets of transducer elements, enabling active focus in an elevational direction. The disclosed transducer array includes an array of first electrodes arranged in a first direction on a first surface of a piezoelectric material, and an array of second electrodes arranged in a second direction, perpendicular to the first direction on a second surface of the piezoelectric material, opposite the first surface. Switching circuits selectively and operatively connect first electrodes to a reference signal channel and driving signal channels, and second electrodes to driving signal channels, to selectively apply and read differential signals across the first and second electrodes. Embodiments include a piezoelectric material with two or more regions, with shapes that define two or more insonation directions.

Description

Inventor: Manders et alUltrasound Transducer Array with Selectively Coupled Reference ElectrodesFIELD OF THE INVENTION

[0001] The current disclosure relates generally to inspection of manufactured parts, particularly to inspection of manufactured parts using ultrasound transducer arrays formed by transducer elements comprising multiple reference or ground elements.BACKGROUND OF THE INVENTION

[0002] Nondestructive testing is a way to inspect and evaluate materials, components or assemblies without causing damage. Nondestructive testing may be used to find defects in manufactured parts such as tubulars, pipelines, casings, gears, airplane wings, wheels, and more. In the oil and gas industry, fluid-carrying structures such as pipelines and downhole tubing are critical components for the transportation and extraction of fluids. These structures or tubulars may be a well or pipes for carrying hydrocarbons or water, generally having a long, narrow form factor. A well includes cased and uncased wells within a surrounding formation, at any stage from during drilling to completion to production to abandonment. Cracks are a type of defect that are of particular interest as they are a major cause of failure in manufactured parts. Cracks are often present in welds and seams. Accurate and efficient detection of structural defects is essential for the safe and reliable operation of these structures.

[0003] Ultrasonic testing is a favored form of nondestructive testing where ultrasonic waves pass into a material or manufactured product that is being tested and reflect off defects to return to the transducer to be detected. However, it is difficult to detect cracks as the ultrasound waves may not always be reflected from cracks back to the transducer such that they can be detected, or only weak reflections may be generated, requiring the separation of a reflected signal from a crack from amongst all the noise encountered during inspection. Further, the surface from which a crack emanates is often a strong reflector, making it difficult to detect a weaker crack signal. In handheld nondestructive testing applications, cracks are somewhat easier to detect cracks as the operator can slowly and repeatedly inspect an area while manually interpreting the data on the display. An operator with years of experience canInventor: Manders et alusually detect a crack from interpreting remaining crack signals over a plurality of views. However, it is challenging for an operator to manually inspect large structures.

[0004] The precision of ultrasonic inspections is influenced by the location of a focal point of the emitted ultrasonic waves, as this impacts the resolution of the reconstructed image frame. Focused ultrasound waves can be used to reconstruct smaller defects due to a higher resolution and offer a clearer picture by minimizing scatter and noise. Focusing of an ultrasound beam at a fixed focal depth from an ultrasound transducer is achieved by acoustic lenses, and dynamic focusing can be achieved in the active plane of a transducer array by delaying signals to individual transducer elements.

[0005] The travel directions of an emitted ultrasound wave also significantly affect the detectable features, as images are reconstructed from the reflected waves. Angled features in a target might not reflect ultrasound energy back to a transducer in numerous configurations. For instance, strong specular reflections are received at a transducer when a wavefront travels nearly perpendicular to a target surface, while significant reflections from angled features are obtained when insonated with ultrasound waves at an angle. Nonetheless, constraints in ultrasound transducer array configuration and positioning, or the dimensions of the imaging tool, may restrict the number of specially configured arrays within a single tool.

[0006] The automation of crack detection is relevant when inspecting large areas such as pipelines which may be hundreds of kilometers long, downhole casings which may be many kilometers long, or in continuously manufactured products such as parts or slabs of material that may be continuously formed all day. Certain physical aspects about the tubulars such as pipelines and casings are pre-known or assumed, such as the diameter, section length, connection type, and expected weld connection location and orientation, such as transverse welds and longitudinal welds. Obtaining high resolution imaging data from targets of various shapes is important for proper defect characterization.

[0007] The inventors have appreciated a need for improved methods and systems for the automated detection of cracks in pipelines and downhole tubing that overcomes the above noted limitations.Inventor: Manders et alSUMMARY OF THE INVENTION

[0008] One general aspect includes an acoustic imaging system for inspecting manufactured parts an ultrasonic transducer array may include: a first array of signal electrodes on a first surface of a piezoelectric material forming a plurality of ultrasonic transducer elements defining the ultrasonic transducer array along a first direction; and a second array of reference electrodes on a second surface of the piezoelectric material opposite the first surface, the second array formed along a second direction orthogonal to the first direction, each of the reference electrodes further defining each of the plurality of ultrasonic transducer elements. The system also includes coupling circuits selectively defining a first configuration and a second configuration. The system also includes where the first configuration is defined by coupling: one or more of the signal electrodes to one or more of the reference electrodes; remaining uncoupled reference electrodes to one of a reference channel and a high impedance channel; and the signal electrodes to signal channels. The system also includes to sequentially provide differential driving signals across the signals electrodes and the remaining uncoupled reference electrodes to emit one or more ultrasound wavefronts with an elevational focus depth on a passive plane of the ultrasonic transducer array. The system also includes where the second configuration is defined by coupling: the reference electrodes to each other; the reference electrodes to a reference channel; and the signal electrodes to signal channels. The system also includes to detect differential received signals across each of the signal electrodes and the reference electrodes. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0009] Implementations may include one or more of the following features. The acoustic imaging system where an elevational focus depth of the one or more ultrasound wavefronts is based on a distance to a surface of a manufactured part. A number of signal electrodes is greater than a number of reference electrodes. The number of signal electrodes may include between 128 to 1024 electrodes and the number of reference electrodes may include between 2 and 25 electrodes. The acoustic imaging system may include control circuits for controlling the coupling circuits. The reference electrodes are arranged as symmetrically opposing pairs of reference electrodes arranged around a central second electrode. Each of the symmetrically opposing pairs of reference electrodes are coupled. A height of each of theInventor: Manders et alsignal electrodes is equal to a total width of the second array of reference electrodes. A height of each of the reference electrodes is equal to a total width of the first array of signal electrodes. A method for imaging a manufactured part using the acoustic imaging system may include the steps of: a) selectively coupling, by the coupling circuits, at least one reference electrode to one of a reference channel and a high impedance channel; b) selectively coupling, by the coupling circuits, a remainder of the reference electrodes to one of the signal electrodes; c) selectively coupling, by the coupling circuits, the signal electrodes to signal channels; d) providing a differential driving signal across the selectively coupled at least one reference electrode and the signal electrodes; e) repeating a) to d) for different at least one reference electrodes, to cause the ultrasonic transducer array to emit ultrasound waves focused on an elevational plane; f) selectively coupling, by the coupling circuits, the reference electrodes to a reference channel; g) receiving ultrasound wave reflections and detecting differential received signals across the signal electrodes and the reference electrodes, to generate received ultrasound signals; and h) beamforming the received ultrasound signals to form elevational focused imaging data of the manufactured part. Step e) further may include applying transmit delays to the differential driving signals for the different at least one reference electrodes. The least one reference electrode in a) further may include an opposing pair of reference electrodes. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0010] One general aspect includes an acoustic imaging system for inspecting manufactured parts. The acoustic imaging system also includes a first ultrasonic transducer array may include a first plurality of transducer elements formed by an array of first signal electrodes, a first reference electrode and a first piezoelectric material therebetween, the first ultrasonic transducer array for emitting an ultrasound wavefront in a first direction; a second ultrasonic transducer array may include a second plurality of transducer elements formed by an array of second signal electrodes, a second reference electrode and a second piezoelectric material therebetween, each of the second signal electrodes electrically coupled to corresponding each of the first signal electrodes, the second ultrasonic transducer array for emitting an ultrasound wavefront in a second direction; and coupling circuits selectively defining a first configuration, a second configuration and a third configuration. The system also includes where a first configuration is defined by coupling: the first reference electrode and the second reference electrode to a reference channel: and the first signal electrodes and the second signal electrodes to signal channels. The system also includes to provide differential driving signals to the first plurality of transducer elements to emit ultrasound wavefronts in a firstInventor: Manders et aldirection and to the second plurality of transducer elements to emit ultrasound wavefronts in a second direction. The system also includes where a second configuration is defined by coupling: the first reference electrode to a reference channel the second reference electrode to a high impedance channel; and the first signal electrodes to signal channels, to detect first received signals from the first plurality of transducer elements. The system also includes where a third configuration is defined by coupling: the second reference electrode to a reference channel; the first reference electrode to a high impedance channel; and the second signal electrodes to signal channels. The system also includes to detect second received signals from the second plurality of transducer elements. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0011] Implementations may include one or more of the following features. The acoustic imaging system where a shape of the first piezoelectric material is different to a shape of the second piezoelectric material. The reference channel is electrical ground. A method for imaging a manufactured part using the acoustic imaging system may include the steps of: a) selectively coupling, by the coupling circuits, the first reference electrode and the second reference electrode to a reference channel; b) selectively coupling, by the coupling circuits, the first signal electrodes and the second signal electrodes to signal channels; c) providing differential driving signals to the first plurality of transducer elements and to the second plurality of transducer elements, to emit ultrasound waves in a first direction from the first ultrasonic transducer array and in a second direction from the second ultrasonic transducer array; d) selectively coupling, by the coupling circuits, the second reference electrode to a high impedance channel; e) receiving first ultrasound wave reflections during a first receive window and detecting first differential received signals across the first plurality of transducer elements, to generate first received ultrasound signals; f) selectively coupling, by the coupling circuits, the first reference electrode to a high impedance channel and the second reference electrode to a reference channel; g) receiving second ultrasound wave reflections during a second receive window and detecting second differential received signals across the second plurality of transducer elements, to generate second received ultrasound signals; and h) beamforming the first received ultrasound signals and the second received ultrasound signals to form imaging data of the manufactured part. Step c) further may include applying transmit delays to the differential driving signals, to emit steered ultrasound waves. Beamforming the first received ultrasound signals forms a first imaging frame of the manufactured part andInventor: Manders et albeamforming the second received ultrasound signals forms a second imaging frame of the manufactured part. Beamforming parameters for beamforming the first received ultrasound signals are different to beamforming parameters for beamforming the second received ultrasound signals. A time defining the first receive window is based on one or more of a standoff distance of the first ultrasonic transducer array to a surface of the manufactured part and a manufactured part thickness. A time defining the second receive window is based on one or more of a stand-off distance of the second ultrasonic transducer array to a surface of the manufactured part, a manufactured part thickness and an angle between the second ultrasonic transducer array and a surface of the manufactured part. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0012] Further aspects of the methods and systems as described herein are set out below and in the appended claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Various objects, features and advantages will be apparent from the following description of embodiments of the methods, systems and devices as described herein, as illustrated in the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of various embodiments of the methods, systems and devices as described herein.

[0014] FIG. 1 is a schematic representation of an imaging device deployed in a downhole wellbore as a tool string in accordance with one embodiment as described herein.

[0015] FIG. 2 is a schematic representation of an imaging device deployed in a pipeline as an inline inspection tool string in accordance with one embodiment as described herein.

[0016] FIG. 3 is a schematic view of an acoustic array in an angled arrangement in accordance with one embodiment as described herein, including a schematic view of a reference coordinate system.

[0017] FIG.4 is a schematic exploded representation of a divided referenced transducer array in accordance with an embodiment as described herein.Inventor: Manders et al

[0018] FIG. 5A is a schematic exploded representation of a blended transducer array in accordance with an embodiment as described herein.

[0019] FIG. 5B is a schematic partially exploded representation of a blended transducer array in accordance with an embodiment as described herein.

[0020] FIG. 6A is a schematic representation of a blended transducer array in accordance with a further embodiment as described herein.

[0021] FIG. 6B is a schematic cross-sectional representation of a blended transducer array in accordance with a further embodiment as described herein.

[0022] FIG. 7 is a block diagram of an imaging device in accordance with one embodiment as described herein.

[0023] FIG. 8A is a block diagram of an imaging device showing a transducer array in accordance with one embodiment as described herein.

[0024] FIG. 8B is a block diagram of an imaging device showing a transducer array in accordance with one embodiment as described herein.

[0025] FIG. 9 is a schematic representation of an ultrasound field focused in an elevational direction, from a divided reference transducer array in accordance with an embodiment as described herein.

[0026] FIG. 10 illustrates the root mean squared (RMS) acoustic pressure across the field of a transducer array in an elevational direction, in accordance with embodiments as described herein.

[0027] FIG. 11 is a flow diagram for carrying out the method in accordance with one embodiment as described herein.

[0028] FIG. 12A is a flow diagram for carrying out the method in accordance with one embodiment as described herein.

[0029] FIG. 12B is a continuation of the flow diagram of FIG. 12A for carrying out the method in accordance with one embodiment as described herein.

[0030] FIG. 13A is a flow diagram for carrying out the method in accordance with one embodiment as described herein.

[0031] FIG. 13B is a continuation of the flow diagram of FIG. 13A for carrying out the method in accordance with one embodiment as described herein.Inventor: Manders et alDETAILED DESCRIPTION OF THE INVENTION

[0032] With reference to the accompanying figures, various aspects of the method, system and device as described herein will now be described. For the purposes of illustration, components depicted in the figures are not necessarily drawn to scale. Instead, emphasis is placed on highlighting the various contributions of the components to the functionality of various aspects as described herein. Several possible alternative features are introduced throughout this description and described accordingly. It is to be understood that, according to the knowledge and judgment of persons skilled in the art, such alternative features may be substituted in various combinations to arrive at different embodiments as described herein. For the sake of simplicity and clarity, the same reference numbers have been used in different figures to show similar or corresponding elements throughout the figures and description.

[0033] Systems and methods are disclosed for ultrasonic testing of manufactured parts to detect flaws in a target, using one or more ultrasound transducer arrays with a divided common or reference electrode for selecting subsets of transducer elements within said transducer array. An acoustic imaging tool generally comprises an imaging tool or device 10 for imaging a fluid-carrying tubular 2 with a circular cross section for carrying fluids such as hydrocarbons, natural gas or water, such as an oilwell casing as illustrated in FIG. 1, or a pipeline as illustrated in FIG. 2, and having an elongate, cylindrical form factor through which an imaging device 10 can move longitudinally. To assess the condition and environmental impact of the well or pipeline, a tubular can be assessed to identify such flaws which contribute to wall loss, such as cracks. Remaining wall thickness, which is the obverse of wall loss, can be used to calculate the burst pressure strength of the tubular.

[0034] The focusing of ultrasound waves in an active or azimuthal plane of a one-dimensional (1D) transducer array can be achieved by delaying signals to individual transducer elements. On the contrary, focusing an ultrasound wave on an elevational or passive plane, perpendicular to an imaging or active plane, depends on the fixed size and configuration of individual transducer elements in the 1 D transducer array. Typically, a fixed-point focal length acoustic lens is used to focus ultrasound waves on the elevational or passive plane at a fixed distance from the transducers, thereby improving elevational resolution at that focal depth. However, both the size of transducer elements and the use of a lens are constant and cannot be controlled during operation of a 1 D array, resulting in a fixed elevational resolution. It is an object of the present disclosure to provide systems and methods to focus an ultrasound wave on an elevational direction of a transducer array.Inventor: Manders et al

[0035] With reference to FIG. 1 , the imaging device 10 generally comprises a transducer array 12, an on-board processor, and one or more centralizing elements 30. The device may be part of a tool string or operated alone. Wells include cased and uncased wells, at any stage from during drilling to completion to production to abandonment. An operations site 18 deploys the device into the tubular and retrieves data from the imaging device 10. The imaging device 10 includes a connection to a deployment system for running the imaging device 10 into the tubular 2 and removing the device 10 from the well. Generally, the deployment system is wireline 17 or coiled tubing that may be specifically adapted for these operations. Other deployment systems can also be used, including downhole tractors and service rigs. The data is processed and visualized at a computer 19, normally remote from the operations site 18.

[0036] With reference to FIG. 2, inline inspection vehicles or inline inspection tools, also known as “smart pigs” or “pigs”, move inside pipelines 2, using a range of sensor technologies to inspect pipelines for defects. Inline inspection tools are designed to navigate the complex geometry of pipelines, including bends, valves, and other fittings, while providing detailed information about the pipeline’s condition. Pipelines typically include multiple beacons 3, at intervals along the length of the pipeline, with access to a communications network. Metal wall loss in a tubular can result from corrosion 6, pitting 7, cracks 8, and milling, or other forms of mechanical damage such as deformation of some or all the sections of the liner due to mechanical stress through compression, tension, and torsion. During its lifetime, the structural integrity of a tubular can become compromised, which can lead to leaks 9 or failures.

[0037] In an embodiment illustrated in FIG. 2, the imaging device 10 is an inline inspection tool string comprising multiple tool string vehicles, or operated alone. The imaging device 10 typically has an elongate form factor and is sized to be deployable within the fluid-carrying tubular 2. A tool string may include multiple mechanically and electrically connected tool string vehicles including plural sensor modules, sensor arms, drive cups, centralizer discs, heat sinks thermally coupling the electronics to an exterior of the sensor modules, and control modules, such as one or more sensor vehicles 10a, one or more battery vehicles 10b, and one or more imaging vehicles 10c. The tool is versatile and can be customized on-site for each job, using different sensors or imaging configurations. An operations site 18 deploys the device into the tubular, and data is then retrieved from the imaging device 10. The data is processed and visualized at a computer 19, normally remote from the operations site. Identifying cracks over the full extent of the tubulars presents problems for storing acoustic images and processing them. To obtain high resolution images, the transducer array mustInventor: Manders et alemit and receive focused ultrasound wavefronts and capture a frame or slice every few millimeters, which typically results in thousands of slices and terabytes of data. However, at practical memory limits, frame rates and processing speeds, it becomes very difficult to log pipelines or wells that are many kilometers long.

[0038] The imaging device 10 generally comprises one or more transducer arrays 12. The one or more transducer arrays 12 are configured in one or more outward-facing arrangements that insonify a cross section of the wellbore or tubular 2, from a standoff distance. Acoustic waves 20 created by one or more of elements in the transducer array 12, such that energy is generally focused along a line to form what is called a scanline 50, travel towards the inner surface or circumference 22 of the wellbore or tubular, and a portion of the ultrasound waves continues outwards to the outer surface or circumference 24 of the wellbore or tubular 2. In embodiments, the one or more transducer arrays 12 are facing radially outward and typically in a rotationally offset fashion to create a helical arrangement of sensors. In embodiments, transducer arrays 12 are distributed around a section or the totality of the circumference of a tool housing. The transmitted waves 20 may be a plane or curved wavefront, as described in further detail below. Multiple transmitted waves 20 may be transmitted concurrently or independently. As the imaging device 10 moves longitudinally through the wellbore or tubular 2, the one or more transducer arrays 12 capture frames of these cross sections, preferably on the order of millimeters. The logging speed and frame rate determines the axial resolution. The reflections of these acoustic waves from the wellbore or tubular features are converted to digital signals, often called raw radiofrequency or RF data. The scanlines are then assembled by the processor to form one frame that approximates one slice of the imaged location. Thousands of these slices are combined to create a 3D visualization of the imaged target 2.

[0039] In embodiments, imaging device 10 comprises one or more transducer arrays 12 distributed radially around the totality of the circumference of the tool housing 16 of the device 10, facing radially away from the imaging tool 10 towards the wall of the target or tubular 2, as illustrated in FIG. 3. Such a ring-shaped transducer arrangement captures a cross-sectional slice of the well covering 360° around the array 12. In embodiments, the one or more transducer arrays 12 are formed as a frustoconical outward facing arrangement, angled to form an oblique-shaped field of view, at an angle p of 10-45°, preferably about 20°, as illustrated in FIG. 3. In further embodiments, an array assembly or blended transducer array comprises first transducer elements 13 facing away from the imaging device or tool 10 towardsInventor: Manders et althe wall of the target or tubular 2, and further transducer elements 13 which share a common reference with the first transducer elements, arranged in a frustoconical outward facing configuration with an oblique field of view at an angle p, described in detail below. Thus, in these embodiments, a surface of the transducer arrays 12 or array assemblies are facing partially in the longitudinal direction of the device. In this arrangement, much of the sound wave reflects further down the tubular, but a small portion backscatters off imperfections on the surfaces or voids within the wall, back towards the transducer, per PCT Application WO 2016 / 201583 published December 22, 2016, to Darkvision Technologies. FIG. 3 shows acoustic pulses transmitted towards the inner wall, most of which bounces downward (as represented by the dashed lines) and some backwards (not illustrated) to the transducer array 12. Some of the wave energy propagates to the outer wall, then bounces downward and partially back to the transducer. Note that the angles of the waves and reflected waves in FIG.3 aren’t necessarily shown accurately, but in a manner that allows for the conceptualization of the waves.

[0040] For clarity in explaining the present method and system, and with reference to FIG. 3, it is assumed that there is a 3D volume of ultrasound data made up of cross-sectional frames (i.e. in the r-0 plane) of the target, which frames are stacked together and extend longitudinally (z). Thus, each frame is an image in coordinates of azimuth and radius (O / r), and stacking frames completes the 3D image by incrementing in the axial (z) dimension. The native units for tubular volume may be cylindrical (r, 0, z). Ultrasound reflections are sampled to capture both positive and negative pressures. The signals are demodulated to create images with pixels of absolute signal energy, for example using a Hilbert Transform. A single frame comprises a plurality of scanlines 50 (0) by a plurality of samples (time or radius zi), where the brightness of each pixel represents the reflected energy at that time and scanline. The raw RF data may be stored in memory or deconvolved (e.g. using a Hilbert transform) to store intensity values in memory, using the native polar coordinate (r, 0, z) of the radial array moving axially in the tubular. Further processing on this data is maintained in polar coordinates to preserve the data and avoid Cartesian approximations.

[0041] In operation, a typical data flow includes acquiring cross-sectional or substantially cross-sectional frames of the tubular and storing them as scanlines, which creates a natively polar coordinate system for a radial array. During subsequent visualization, as described in detail below, the stored images can be visualized in the polar domain directly, or may be converted to Cartesian coordinates, with neighboring polar pixels combined for eachInventor: Manders et alCartesian pixel, and rendering makes the compiled images of the tubular into an intuitive display. These Cartesian images are loaded into video memory as X, Y, Z pixels (aka voxels). A GPU operates on these Cartesian pixels to create visualization appropriate to a 2D monitor used by operators. The scan conversion from acquired ultrasound images to displayed images can be pre-computed for efficient viewing.

[0042] Each of the one or more transducer arrays 12 of the imaging tool 10 comprise a plurality of acoustic transducer elements 13, preferably operating in the ultrasound band. The frequency of the ultrasound waves generated by the transducer(s) is generally in the range of 200 kHz to 30 MHz, and may be dependent upon several factors, including the fluid types and velocities in the well or pipe and the speed at which the imaging device is moving. The use of a relatively large number of elements generates a fine resolution image of the object. In most uses, the wave frequency is 1 to 10 MHz, which provides reflection from micron features. The transducers may be piezoelectric, such as the ceramic material, PZT (lead zirconate titanate).

[0043] The operating principle of piezoelectric transducers is well known. A piezoelectric material will mechanically deform when a voltage is applied across it. Inversely, when mechanical pressure is applied to a piezoelectric material, it generates a voltage proportional to the applied force. A single piezoelectric transducer comprises a piezoelectric material or a composite piezoelectric material, with a signal electrode and reference electrode arranged on opposing surfaces of the transducer material. A voltage signal is applied across the signal and reference electrodes to generate a mechanical wave proportional to the signal, and an electrical signal can be read across the electrodes when mechanical stress is applied to the transducer, the signal being proportional to the mechanical stress applied. In the prior art, when an array of transducers is formed, a single reference or ground electrode is typically used for all transducer elements. A backing layer can be used to control the direction of a mechanical wave, such as a sound wave, emitted by a transducer element or array.

[0044] One or more of the ultrasound transducer arrays 12 of the imaging device may comprise a divided reference transducer array 100, as illustrated in the schematic exploded representation of FIG. 4. A divided reference transducer array 100 comprises a piezoelectric material 102, disposed between a plurality of first or reference electrodes 110 arranged in a linear array on a first surface 104 of the piezoelectric material 102, and a plurality of second or signal electrodes 112 arranged in an array in a direction perpendicular to the direction of the array of first electrodes on a second surface 106, opposite the first surface 104. In combination, the first electrodes 110, the second electrodes 112 and the piezoelectric materialInventor: Manders et al102 define a plurality of acoustic transducer elements 13 that make up the transducer array 12. In embodiments, the piezoelectric material includes a composite piezoelectric material, as is known in the art. The plurality of first electrodes 110 and the plurality of second electrodes 112 may be formed on the piezoelectric material using known methods including, but not limited to, physical vapor deposition (PVD), chemical vapor deposition (CVD), electroplating, thermal spraying, chemical metal layer with electrolytic plating, thick metal layer application, and printed electronics, among others.

[0045] The divided reference transducer array 100 may further include a backing layer (not shown), for example, to direct ultrasound waves away from the array. In embodiments, a backing layer may be formed on the same side as first surface 104, to direct ultrasound waves in the direction of second surface 106. In a preferred embodiment, a backing layer may be formed on the same side as second surface 106, to direct ultrasound waves in the direction of first surface 104, while allowing the plurality of signal electrodes 112 to remain electrically isolated from a medium and target.

[0046] In embodiments, the total width 114 of the array of the plurality of first electrodes 110 is substantially equal to the total height 116 of the array of the plurality of second electrodes 112, and the total height 118 of the array of the plurality of first electrodes 110 is substantially equal to the total width 119 of the array of the plurality of second electrodes 112. Without loss of generality, a size of a transducer element is defined by the sizes of the reference and signal electrodes defining said transducer element, and the terms transducer element and electrode are used interchangeably herein. The size of a transducer element in a one-dimensional array is defined by the overlapping areas of signal and reference electrodes on opposing surfaces of the piezoelectric material 102, which further defines an element width, in the direction of the array, and an element height or elevation in a direction perpendicular to the direction of the array. The total width of an array is the sum of the individual widths of each transducer element, plus the spacing between elements. The distance between the center of successive transducer elements, which considers the element width and spacing between elements, is the pitch. For an n-element array of equal-width transducer elements, the total array width is (nJ x (element width) + (n-1) x (element spacing), and the total array height is equal to the element height or elevation. The total array width of an array made up of non-equal transducer elements is the sum of each of the individual widths and the sum of the individual spacings.

[0047] In an embodiment, the plurality of second electrodes 112 define transducer elements of equal pitch and define 32 to 2048 elements and preferably 128 to 1024 elements. In anInventor: Manders et alembodiment, the plurality of first electrodes 110 are arranged symmetrically around a central axis along the azimuthal direction. In an embodiment, the plurality of first electrodes 110 comprise an odd number. In further embodiments, the plurality of first electrodes 110 comprise between 4 and 25 electrodes. In embodiments, the plurality of first electrodes 110 comprise 8 or 9 electrodes. In a further embodiment, a central electrode of the plurality of first electrodes has a first width, and the remaining symmetrically arranged electrodes of the plurality of first electrodes have a second width. In yet a further embodiment, the two outermost electrodes of the plurality of first electrodes have a third width. For example, the width of a central electrode is twice the width of the remaining plurality of first electrodes. In additional embodiments, the plurality of first electrodes 110 are arranged in an asymmetrical configuration, with each electrode having one or more of different widths and different spacings to adjacent electrodes.

[0048] An acoustic transducer element 13 can both transmit and receive sound waves. The shape and size of an array, or limitations of the electronics may mean that each transmit and receive event takes place on less than the full physical array, i.e., an aperture 15. The aperture 15 is a set of neighboring transducer elements that individually contribute towards the constructive wavefront and increase its acoustic energy. The number N of scanlines 50 that make up a full frame may be the same as the number of elements M in the array, but they are not necessarily the same. For example, a 256-element array may operate with a 64-element transmit aperture that slides from one side to the other, capturing many smaller scanlines than if the whole array were pulsed and received at once. The elements in the aperture are selected from the whole array by multiplexors (MUX). Normally these are a symmetrical set of elements opposite the part spot to be insonified, i.e. the spot and aperture center have the same azimuthal angle 0. Multiple transducer elements 13, per aperture 15, operate in a phase delayed configuration to generate a scanline. There may be as many scanlines 50 as elements by changing the aperture by a single element for each scanline. The apparent origin of the wave can be synthesized within the device, referred to as a transmission point, by the set of transducers, or the aperture 15. In embodiments, a scanline 50 may be steered at an angle with respect to a normal direction of surface 104.

[0049] In a further embodiment, the divided reference transducer array 100 may comprise a blended transducer array or array assembly 200, as illustrated in the schematic exploded representation of FIG. 5A and the partially exploded schematic representation of FIG. 5B. The blended transducer array 200 comprises a piezoelectric material 202, disposed between aInventor: Manders et alplurality of first or reference electrodes 210 and a plurality of second or signal electrodes 212 arranged in an array in a direction perpendicular to the direction of the array of first electrodes. The piezoelectric material 202 comprises a first region 204 and a second region 206, each having a shape defining an insonation direction. For example, as schematically illustrated in FIG. 5A and FIG. 5B, the first region 204 and second region 206 are generally flat and arranged at an angle with respect to each other. Alternatively, as illustrated in FIG. 3, FIG. 6A and FIG. 6B, the first region 204’ has a general ring shape, and the second region 206’ has a general conical shape. A subset of the plurality of first electrodes 210 are located on a first surface 205 of the first region 204, 204’ and the remaining first electrodes are located on a first surface 207 of the second region 206, 206’. The plurality of second electrodes 212 are located on a second surface 208 of the first region and a second surface 209 of the second region. As illustrated in the figures, the plurality of second electrodes 212 span across both the first region 204, 204’ and second region 206, 206’. The blended transducer array 200 may further comprise a backing layer (not shown). In combination, the first electrodes 210, the second electrodes 212 and the first region 204, 204’ define a plurality of acoustic transducer elements 13, and the first electrodes 210, the second electrodes 212 and the second region 206, 206’ define a second plurality of acoustic transducer elements 13, depending on the selected second electrodes 212, as described in further detail below.

[0050] In some embodiments, a relative orientation between the surface 207 in region 206 and the surface 205 in region 204 is adjustable. Stated differently, the transducer array 200 may include one or more mechanisms, features, or other means configured to selectively vary an included angle between surface 205 and surface 207 while the multiple components forming the array 200 remain coupled as described herein.

[0051] Such adjustability may be advantageous, for example, when imaging tubular targets having different diameters. In particular, varying the included angle between surface 205 and surface 207 may facilitate causing acoustic wavefronts emitted by transducer elements 13 of the array 200 on the surface 206 to impinge on, and / or reflect from, an inner surface of a tubular target at one or more desired incidence angles, thereby improving thickness measurement, defect detection, signal-to-noise ratio, coverage, and / or overall image quality.

[0052] In some embodiments, the included angle between surface 205 and surface 207 is selected as a function of tubular diameter. For example, when imaging tubular targets having relatively larger diameters, surface 205 and surface 207 may be arranged to form a smaller included angle, whereas when imaging tubular targets having relatively smaller diameters,Inventor: Manders et alsurface 205 and surface 207 may be arranged to form a larger included angle. In this manner, the same imaging tool may be configured to accommodate a range of tubular geometries by adjusting the relative orientation of the two surfaces, without requiring decoupling, replacement, or reassembly of the transducer array components.

[0053] In embodiments in which the surface 205 is cylindrical and the surface 207 is conical, the included angle may be defined and / or determined with reference to a cross-sectional view, although other surface geometries and angle definitions may additionally or alternatively be used.

[0054] With reference to FIG. 5A and FIG. 5B, and similarly to the transducer array 100 described above, the total width of the array of the plurality of first electrodes 210 across the first region 204, 204’ and the second region 206, 206’ is substantially equal to the total height of the array of the plurality of second electrodes 212 across the first region 204, 204’ and the second region 206, 206’, and the total height of the array of the plurality of first electrodes 210 across each of the first region 204, 204’ and the second region 206 is substantially equal to the total width of the array of the plurality of second electrodes 112 across each of the first region 204, 204’ and the second region 206, 206’.

[0055] In an embodiment, the plurality of second electrodes 212 define transducer elements of equal pitch and define 32 to 2048 elements and preferably 128 to 1024 elements. In an embodiment, the plurality of first electrodes 210 comprise at least one electrode on each of the first region 204, 204’ and the second region 206, 206’, and may comprise an odd or even number of electrodes. In embodiments, the plurality of first electrodes 210 comprise between 2 and 25 electrodes. FIG. 6B schematically illustrates a cross-sectional view of a non-limiting example showing two first electrodes 210 on each of the first region 204’ and second region 206’. In further embodiments, the plurality of first electrodes 210 in each of the first region 204, 204’ and second region 206, 206’ are arranged symmetrically around a central axis of each region along the azimuthal direction. In a further embodiment, for each region 204, 204’, 206, 206’, a central electrode of the plurality of first electrodes has a first width, and the remaining symmetrically arranged electrodes of the plurality of first electrodes have a second width. In yet a further embodiment, in each region 204, 204’, 206, 206’, the two outermost electrodes of the plurality of first electrodes have a third width. In additional embodiments, the plurality of first electrodes 210 are arranged in an asymmetrical configuration, with each electrode having one or more of different widths and different spacings to adjacent electrodes. It is to be understood that the exemplary embodiments illustrated in FIGS. 4, 5A, 5B, 6A andInventor: Manders et al6B are non-limiting and the number of first electrodes, second electrodes, and their relative configuration and number aren’t necessarily shown accurately, but in a manner that allows for the conceptualization of the embodiments as described herein.

[0056] The imaging device 10 may further comprise an acoustic lens covering an outer surface of one or more of the transducer arrays 12. The acoustic lens may be convex or concave, or may be a concave or convex logarithmic lens having an extended focal zone. The skilled person will appreciate that focusing also depends on the relative speed of sound from the lens material to fluid. In embodiments, a blended array assembly 200 may include a first acoustic lens for transducer elements defined in the first region 204, 204’, and a second acoustic lens for transducer elements defined in the second region 206, 206’.

[0057] In embodiments, a convex lens is used. The convex lens is made of a material having an acoustic velocity less than the acoustic velocity of the fluid in the tubular. Typically, well fluid has an acoustic velocity of approximately 1300 to 1700 m / s. A suitable lens material having a lower acoustic velocity is room temperature vulcanization (RTV) silicone, which has an acoustic velocity of approximately 900 to 1050 m / s. With a convex lens, the elevation of the transducer array elements is generally from 5 to 50 mm, depending on the lens curvature and size of the tubular, and preferably 15 mm.

[0058] In further embodiments, a concave lens is used. The material of the concave lens preferably has an acoustic impedance close to the fluid in the tubular, and has a higher acoustic velocity than the fluid within the tubular. Suitable materials include hard plastics such as polymethylpentene (PMP) (e.g. TPXTM), polystyrene (PS), and poly(methyl methacrylate) (PMMA). The elevation of the transducer elements is generally from 5 to 50 mm depending on lens curvature and size of the tubular, and preferably 15 mm.

[0059] In yet further embodiments, a logarithmic lens is used. The logarithmic lens is shaped to create an extended focal zone that can produce sharp images at a range of distances, i.e. images having a high depth of field. Having an extended focal zone is advantageous because a range of depths from inside a tubular to the outside of the casing or liner and everything in between can be imaged with the same tool. An extended focal zone also allows for wells having different diameters to be imaged with the same tool. The logarithmic lens can be concave or convex. A concave logarithmic lens would be made of a material having a higher velocity than the fluid in the tubular, such as polymethylpentene (PMP) (e.g. TPXTM), polystyrene (PS) or poly(methyl methacrylate) (PMMA). A convex logarithmic lens would be made of a material having a lower velocity than the fluid within the tubular, such as RTVInventor: Manders et alsilicone. The elevation of the transducer elements is generally from 5 to 50 mm depending on lens curvature and size of the tubular, and preferably 15 mm.

[0060] In ultrasound arrays, multiple discreet omnidirectional pulses are emitted from the plural transducer elements 13, which waves interfere constructively and destructively to produce a wavefront moving in the direction of the scanline. As known in the art, altering the timing of the pulse at each transducer element in an array can steer and focus the wavefront in the active or azimuthal plane, which also corresponds to the imaging plane. In steering, the combined wavefront appears to move away in a direction that is not orthogonal from the transducer face, but still in the plane of the array. In focusing, the waves all converge at a chosen distance from the elements 13. The location of the convergence in the active or azimuthal plane is the focal point and the area insonified defines the resolution of the system. The transmitted wave may or may not be focused at a point on the surface to be imaged. US Patent No. 5,640,371 provides a method and apparatus for acoustic imaging using beam focusing, beam steering and amplitude shading to increase image resolution and overcome side lobe effects, which may be used in pipelines.

[0061] The transmitted wavefront may be described as ‘coherent,’ ‘weakly focused,’ ‘defocused,’ ‘unfocused,’ ‘plane wave’, ‘spherical’, ‘spiral’, ‘divergent,’ or ‘non-convergent’ in as much as the transmitted waves may have some theoretical focal point within or behind the transducer. The transmitted waves may be a plane or curved wavefront, the former having a flat front and the latter having a front that is substantially curved or arc-shaped. Curved I arcshaped waves can be seen as the polar coordinate equivalent of planar waves. The transmitted wavefront from the transducer towards a curved target, such as a pipeline or casing, can be an arc, rather than a flat plane wave. These shapes are created by phase delays of the pulses emitted by each transducer element. Notably, these fronts do not converge or focus on the surface of the target but rather strike the surface of the target at an angle of incidence with respect to the normal of the surface. The angle of incidence is chosen based on various parameters, such as the density of a fluid contained within a tubular. For example, the tubular is imaged at -20°, 20° and 0° when it contains water, and the tubular is imaged at -16.5°, 16.5° and 0° when it contains crude oil. Preferably, a curved wavefront hits the inside of a tubular target at the same angle of incidence relative to the normal of the surface of the tubular along the whole area of sonification. The angle of incidence is what defines the overall steering angles for a transmit. This transmit may be computed by rayInventor: Manders et altracing, knowing the array position relative to the pipe, pipe geometry, speed of sound of fluid, and array geometry.

[0062] The timing of each scan comprises a transmission window Tx, receiving window Rx and dwell period therebetween. As used herein, a scanline 50 is the stream of data received during Rx and may be provided in physical coordinates using the speed of sound. During transmission, the transducers are excited with an electrical pulser that can produce pulses in square, sinusoidal or other waveforms. An excitation signal is applied across one or more signal and reference electrodes located on opposite surfaces of the piezoelectric material and forming the transducer array, for example, as a differential voltage, and may be additionally timed for steering and focusing, as described below. At the end of Tx there is a dwell period while the wave travel outs and back to the transducer element or aperture. During the Rx window, the circuit ‘listens’ to reflections at the transducer element or aperture. There may be multiple reflections along paths of various lengths, so the Rx window is much wider than the Tx window. The reflections are received at the transducer elements 13. The electrical signals of the reflections may be stored in raw form for later, offline beamforming and image reconstructions. Alternatively, the signals are beamformed in real time and the reconstructed image is stored on the imaging device.

[0063] The imaging device 10 comprises a processing circuit for generating and receiving signals from the transducer elements 13 of the one or more transducer arrays 12. The skilled person will appreciate that the circuit may implement logic in various combinations of software, firmware, and hardware that store instructions process data and carry out the instructions. Specialized ultrasound circuits exist to drive and receive arrays of ultrasound transducers, such as LM96511 from Texas Instruments. FIG. 7 is a block diagram of components of the device’s on-board circuits 14 and remote computing system 19, including an onboard computer processor 38 (for display and post processing), FPGA block 84, Summing Amps 86, ADC 85, MUX / DEMUX 82, High Voltage T / R switch 83, High Voltage Pulser 81 , and timing chips. The FPGA is an efficient chip for integrating many logical operations. The block may comprise Tx beamforming 89 and Rx beamforming 88, DVGA control (Digitally controlled Variable Gain Amplifiers, not shown), as well as data processing operations 87, such as B-configuration (brightness configuration) and Doppler processing. Although not shown, the circuit may additionally comprise motor drivers and memory chips. By way of example, the transmission step may include selecting transducer elements 13 in an aperture 15, calculating beamforming timings, loading the pulse timings from the FPGA 84, activating the pulser 81Inventor: Manders et aland multiplexors (MUXes) 82 to pulse all transducer elements 13. The dwell period may be set by the operator based on a nominal diameter of the pipe and speed of sound in the well fluid. The Rx window may be set to capture reflected pulses based on the known, measured or nominal parameters of the target and of the surrounding physical environment. The raw image data is initially stored in memory 36. This may be Terabytes of data. Instructions running on the remote processor include modules for digital receive beamforming, compound processing, wall thickness factor calculation and visualization. Intermediary images, such as a single beamformed image or the compounded image may be stored on the same or separate storage 37. This shows a preferred division of resources for the method described above. However, as computing resources improve, certain processes could be moved onto the device, such as beamforming and compounding. This could also be done during the downtime of the device, when not actively imaging. In this manner, the recovered device is ready to upload fully compounded images to the remote computer for immediate visualization.

[0064] Without loss of generality, each of the circuit and electronic components described with reference to FIG. 7 may comprise multiples of such chips, e.g. the memory may be multiple memory chips. For the sake of computing efficiency, several of the functions and operations described separately above may be combined and integrated within a chip. Conversely certain functions described above may be provided by multiple chips, operating in parallel. For example, the LM96511 chip operates eight transducers, so four LM96511 chips are used to operate an aperture of 32 transducers.

[0065] Each of the plurality of first electrodes 110, 210 and plurality of second electrodes 112, 212 of a transducer array 100, 200 are operatively coupled to a plurality of signal channels 126 to circuits 14 of the imaging device, by a plurality of first channels 122 and a plurality of second channels 124, respectively. In embodiments, one or more of the plurality of first channels 122 are operatively coupled by bridging circuits 130, such that pairs of electrodes of the plurality of first electrodes 110 are electrically coupled together, and the remaining first channels 122’ are operatively coupled to circuits 14 via channels 126. For example, reference electrodes corresponding to symmetric pairs of elements on the first surface 104 are electrically connected, as illustrated in FIG. 8A and FIG. 8B. In embodiments, each of the plurality of first channels 122 are operatively coupled to the respective each of the plurality of first electrodes 110, 210 at more than one location, to compensate for any signal drop over the electrode on the piezoelectric element. In a first non-limiting example, each of the first electrodes 110 is coupled to each of the first channels 122 at opposing ends of the array. InInventor: Manders et ala further non-limiting example, each first electrode 110 is further coupled to the first channels 122 at intermediate points along the array. In this manner, voltage drops across the transducer elements due to the width and elevation of said transducer elements, are mitigated. In embodiments with a blended transducer array or array assembly 200, second electrodes 212 in region 204 are electrically connected to corresponding second electrodes 212 in region 206, for example, as illustrated in the exemplary and non-limiting embodiments of FIG. 5A, FIG. 5B, and FIG. 6B.

[0066] In embodiments, the plurality of first channels 122, 122’ and plurality of second channels 124 are operatively coupled to the plurality of signal channels 126 through switching or selection circuits 120. In a non-limiting example, a transducer array 100 is connected to a MUX / deMUX 82 through switching circuits 120, as illustrated in FIG. 8B. Switching circuits 120 operatively and selectively connect a plurality of signal channels 126, including a reference, common or ground channel 128, from a MUX / deMUX 82 to one or more of the plurality of first channels 122, 122’ and plurality of second channels 124. In embodiments, pairs of channels of the plurality of first channels 122, corresponding to pairs of electrodes of the plurality of first electrodes 110, are operatively coupled within switching circuits 120, rather than by bridging circuits 130. In embodiments, an imaging device 10 further comprises control circuits 132 configured to generate control signals for switching circuits 120 to selectively connect the plurality of channels 126 to one or more of the plurality of first channels 122, 122’ and / or one or more of the plurality of second channels 124, such that signals to and from circuits 14 are transmitted and received to and from one or more transducer arrays 100, 200, as described herein. In embodiments, control circuits 132 are integrated as part of switching circuits 120, as illustrated in the exemplary FIG. 8B. In embodiments, control circuits 132 are separate from switching circuits 120. In embodiments, control circuits 132 generate the control signals based on signals received from circuits 14, for example, received over channels 126, or otherwise. In embodiments with a blended transducer array or array assembly 200, switching circuits 120 further comprise switching circuits 120’, which selectively connect second electrodes 212 in region 204 with corresponding second electrodes 212 in region 206 in a blended transducer array 200, as illustrated in FIG. 6A.

[0067] In operation, during a transmit step, a plurality of driving signals 300 are provided over channels 126 by circuits 14, for example through MUX / deMUX 82, to one or more of the plurality of first electrodes 110 and the plurality of second electrodes 112 across channels 122 and 124, respectively, such that the transducer array 100 generates a desired ultrasoundInventor: Manders et alwavefront. During a receive step, a plurality of received signals 310 are generated across the plurality of first electrodes 110 and second electrodes 112 in response to acoustic ultrasound waves received at the transducer array 100 and transmitted across the plurality of channels 122 and 124, to circuits 14 via channels 126, for example through MUX / deMUX 82. In embodiments, each of the plurality of channels 122 and 124 are coupled directly to one of the plurality of channels 126 during transmit and receive steps. In further embodiments, switching circuits selectively couple one or more channels 122 to one or more channels 126, during transmit and receive steps. In yet further embodiments, during both transmit and receive steps, control circuits 132 selectively control coupling between the plurality of channels 126, and the plurality of channels 122 and 124, based on signals received from circuits 14. In one embodiment, ultrasound signals focused on an elevational plane are emitted and received by one or more transducer arrays 100, 200. In an alternative embodiment, directional ultrasound signals are emitted and received by one or more transducer arrays 200.

[0068] Receive beamforming is understood by persons skilled in the art of ultrasound. In broad terms, the processor uses plural phase delays, pre-stored in a memory (e.g. look-up-table, or LUT) that convolve I shift the signals based on different focal depths. These signals are combined to reconstruct a final imaging frame, whereby weakly focused reflections get diluted and strongly focused reflections are reinforced. As an example, “Delay and Sum” beamforming technique can be used for this purpose.

[0069] In conventional imaging, images are formed by beamforming one line at a time. This will drastically reduce the acquisition rate. To speed up the beamforming, the same channel data can be used with slightly different delays to generate multiple lines, which in preferred embodiments can be extended to generate an entire image slice around the tubular from a single transmit event. This is done by running parallel beamforming on all the scanlines at the same time. This is computationally intensive but allows for much faster image reconstruction.

[0070] After areas of the target are captured from plural angles and then receive beamformed to create plural reconstructed imaging frames, the step of compounding can be used to combine each of these reconstructed imaging frames to create a compounded image using summation of data in the overlapping zone. The summation can be coherent (using RF data) or envelope date (B-configuration). The receive beamforming reconstruction will depend on the transmit delays and geometry of the transducer array. The individual angled images are shifted to the same locations, and corresponding pixels in each image are summed to create pixels of the compounded image. The compounded image removes noises that are notInventor: Manders et alcoherent in the individual images, reinforces reflectors seen in plural angles, and smooths over glints present in only one of the images. In embodiments, various artifacts or signals are filtered out of an imaging frame, and desired features are retained.

[0071] In an embodiment, a divided reference transducer array 100 is operated as a linear phased array ultrasound transducer. In embodiments, afirst subset of the plurality of channels 126 are coupled to the plurality of channels 122, and a second subset of the plurality of channels 126 are connected to the plurality of channels 124. In an embodiment, control circuits 132 configure switching circuits 120 to interconnect a subset of the plurality of channels 126, for example, comprising channels carrying driving signals 300, to the plurality of signal channels 124. Control circuits 132 further configure switching circuits 120 to interconnect at least one of the plurality of channels 126, for example, comprising a channel corresponding to a reference or ground, to the plurality of channels 122. During a transmit step, driving signals 300 are provided to the plurality of signal electrodes 112, and a reference or ground is provided to the plurality of reference electrodes 110, and transducer array 100 emits a desired ultrasound wavefront. In an embodiment, driving signals 300 comprise phase delayed signals, and the desired ultrasound wavefront is a steered ultrasound wavefront in the azimuthal direction. In an embodiment, sparse driving signals are provided to the plurality of signal electrodes 112. During a receive step, received signals 310 are detected by circuits 14, for example, by MUX / deMUX 82, across one or more of the plurality of transducer elements defined by signal electrodes 112.

[0072] In a further embodiment, a divided reference transducer array 100 is used to focus an ultrasound wave on an elevational plane of the array. In embodiments, control circuits 132 configure switching circuits 120 to interconnect a subset of the plurality of channels 126, for example, comprising channels carrying driving signals 300, to the plurality of signal channels 124. During a transmit step, control circuits 132 further configure switching circuits 120 to selectively interconnect one or more of the plurality of channels 126 to one or more of the plurality of channels 122, as follows.

[0073] During a first step, switching circuits are configured to selectively connect one of channels 126, corresponding to reference or ground, to a pair of channels 122 corresponding to the two outermost first electrodes 110. Switching circuits are further configured to selectively connect a different one of channels 126, carrying a driving signal 300, to the remaining channels 122, corresponding to the remaining first electrodes 110. In an embodiment, circuits 130 connect pairs of channels 122 and pairs for first electrodes 110, asInventor: Manders et aldescribed above, and switching circuits 120 selectively connect one channel 122’, corresponding to the two outermost first electrodes 110 in array 100. In this manner, a voltage differential proportional to driving signals 300 is present only across a fraction of each of the plurality of second electrodes 112 in the array, corresponding to the area where the two outermost first electrodes 110 overlap with each of the second electrodes 112, since the same driving signal 300 is provided to the remaining first electrodes. As a result, the piezoelectric material is only activated in these overlapping regions.

[0074] During a second step, switching circuits are configured to selectively connect one of channels 126, corresponding to reference or ground, to a pair of channels 122 corresponding to the two first electrodes 110 adjacent to the two outermost first electrodes 110. Switching circuits are further configured to selectively connect a different one of channels 126, carrying a driving signal 300, to the remaining channels 122, corresponding to the remaining first electrodes 110. In embodiments, a single channel 122’ is connected for each corresponding pair of channels 122 if circuits 130 are included, as described above. In this manner, a voltage differential proportional to driving signals 300 is present on the next two first electrodes, with respect to the step described in the paragraph above, and only the regions of the piezoelectric material with a voltage differential are activated. This process is repeated until all pairs of first electrodes 110 are selectively grounded, and the final, central first electrode 110 is similarly selectively grounded.

[0075] As a result, the combined wavefront of the emitted wave 20 from transducer array 100 is focused on an elevational plane E of the array at a distance F, as schematically illustrated in the non-limiting exemplary array 100 of FIG. 9. The focal distance F is dependent on the number of first electrodes, and the timing of the ground or reference provided during first and second steps, as described above. FIG. 10 illustrates examples of the root mean squared (RMS) acoustic pressure across the field of a transducer array 100 in an elevational direction, when using (a) a single, unfocused, first electrode 110 referenced to ground, (b) five first electrodes 110 selectively referenced to ground as described, and (c) eleven first electrodes 110 referenced to ground as described.

[0076] During a receive step, control circuits 132 further configure switching circuits 120 to interconnect at least one of the plurality of channels 126, for example, comprising a channel corresponding to a reference or ground, to the plurality of channels 122. In embodiments, one or more of the plurality of channels 122 are connected to a high impedance channel, to deactivate transducer regions for the corresponding first electrodes 110 coupled to saidInventor: Manders et alchannels 122. Received signals 310 are detected by circuits 14, for example, by MUX / deMUX 82, across one or more of the plurality of transducer elements defined by signal electrodes 112.

[0077] In embodiments, a first subset of the plurality of channels 126 are coupled to the plurality of channels 122, and a second subset of the plurality of channels 126 are connected to the plurality of channels 124. The switching and control logic described above is performed by circuits 14, for example by one or more of a processor 38 and FPGA 84, such that driving signals 300 are delivered to the plurality of first electrodes 110 and plurality of second electrodes 112, and received signals 310 are received therefrom, as described.

[0078] FIG. 11 is a flowchart of an example process 400 for using a transducer array 100 and imaging device 10, as described above. In some implementations, one or more process blocks of FIG. 11 may be performed by a device.

[0079] As shown in FIG. 11, process 400 may include selectively coupling, by the switching circuits, one or more signal electrodes of the plurality of signal electrodes to the driving and receive circuits, for providing at least a first signal to the selectively coupled one or more signal electrodes (block 402). As also shown in FIG. 11, process 400 may include selectively coupling, by the switching circuits, at least one reference electrode of the plurality of reference electrodes to the driving and receive circuits for providing a reference signal to the selectively coupled at least one reference electrode (block 404). As further shown in FIG. 11, process 400 may include selectively coupling, by the switching circuits, a remainder of reference electrodes from the plurality of reference electrodes to the driving and receive circuits for providing the at least first signal to the selectively coupled remainder of reference electrodes (block 406). As also shown in FIG. 11, process 400 may include providing, by the driving and receive circuits, the at least first signal and reference signal for applying a first differential signal across the selectively coupled at least one reference electrode of the plurality of reference electrodes and the selectively coupled one or more signal electrodes of the plurality of signal electrodes, to generate one or more ultrasound waves from the transducer array (block 408). As further shown in FIG. 11, process 400 may include repeating steps in blocks 404 through 408 for different at least one reference electrodes of the plurality of reference electrodes (block 410). As also shown in FIG. 11, process 400 may include selectively coupling, by the switching circuits, the plurality of reference electrodes to the driving and receive circuits, for providing a reference channel (block 412). As further shown in FIG. 11, process 400 may include selectively coupling, by the switching circuits, the plurality of signalInventor: Manders et alelectrodes to the driving and receive circuits, for providing a plurality of signal channels (block 414). As also shown in FIG. 11, process 400 may include receiving ultrasound reflections at the transducer array and detecting one or more second differential signals across the plurality of signal channels and the reference channel, to form raw ultrasound data (block 416). As further shown in FIG. 11 , process 400 may include processing the raw ultrasound data to form imaging data of the manufactured part (block 418).

[0080] Although FIG. 11 shows example blocks of process 400, in some implementations, process 400 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in FIG. 11. Additionally, or alternatively, two or more of the blocks of process 400 may be performed in parallel.

[0081] FIG. 12A and 12B is a flowchart of another example process 500 for using a transducer array 100 and imaging device 10, as described herein. In some implementations, one or more process blocks of FIG. 12A and 12B may be performed by a device.

[0082] As shown in FIG. 12A and 12B, process 500 may include selectively coupling, by switching circuits, one or more signal electrodes of the plurality of signal electrodes to driving and receive circuits, for providing a first signal to the selectively coupled one or more signal electrodes (block 502). As also shown in FIG. 12A and 12B, process 500 may include selectively coupling, by the switching circuits, at least one reference electrode of the plurality of reference electrodes, perpendicular to the plurality of signal electrodes, to the driving and receive circuits for providing a reference signal to the selectively coupled at least one reference electrode (block 504). As further shown in FIG. 12A and 12B, process 500 may include selectively coupling, by the switching circuits, a remainder of reference electrodes from the plurality of reference electrodes to the driving and receive circuits for providing the first signal to the selectively coupled remainder of reference electrodes (block 506). As also shown in FIG. 12A and 12B, process 500 may include providing, by the driving and receive circuits, the first signal and reference signal for applying a first differential signal across the selectively coupled at least one reference electrode of the plurality of reference electrodes and the selectively coupled one or more signal electrodes of the plurality of signal electrodes, to generate one or more ultrasound waves (block 508). As further shown in FIG. 12A and 12B, process 500 may include repeating steps in blocks 504 through 508 for different at least one reference electrodes of the plurality of reference electrodes (block 510). As also shown in FIG. 12A and 12B, process 500 may include selectively coupling, by the switching circuits, the plurality of reference electrodes to the driving and receive circuits, for providing a referenceInventor: Manders et alchannel (block 512). As further shown in FIG. 12A and 12B, process 500 may include selectively coupling, by the switching circuits, the plurality of signal electrodes to the driving and receive circuits, for providing a plurality of signal channels (block 514). As also shown in FIG. 12A and 12B, process 500 may include receiving ultrasound wave reflections and detecting one or more second differential signals across the plurality of signal channels and the reference channel, to form raw ultrasound data (block 516). As further shown in FIG. 12A and 12B, process 500 may include processing the raw ultrasound data to form imaging data of the manufactured part (block 518).

[0083] Although FIG. 12A and 12B shows example blocks of process 500, in some implementations, process 500 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in FIG. 12A and 12B. Additionally, or alternatively, two or more of the blocks of process 500 may be performed in parallel.

[0084] In yet a further embodiment, blended transducer assembly 200 is used to selectively emit multiple ultrasound wavefronts from one or more transducer regions 204, 206 of transducer assembly 200. In embodiments, control circuits 132 configure switching circuits 120 to interconnect a subset of the plurality of channels 126, for example, comprising channels carrying driving signals 300, to the plurality of signal channels 124, in turn connected to the plurality of second electrodes 212. During a transmit step, control circuits 132 further configure switching circuits 120 to selectively interconnect one or more of the plurality of channels 126 to one or more of the plurality of channels 122, as follows.

[0085] During a first step during transmit, switching circuits 120 are configured to selectively connect one of channels 126, corresponding to reference or ground, to one or more channels 122 corresponding to one or more reference electrodes 210 in first region 204. In embodiments, channels 122 are selected corresponding to all of reference electrodes 210 in first region 204. Switching circuits 120 are further configured to selectively connect to a different one or more channels 126, carrying a driving signal 300, to the remaining channels 122, corresponding to one or more reference electrodes 210 in second region 206. In this manner, a voltage differential proportional to driving signals 300 is present only across each of the plurality of signal electrodes 212 in first region 204, since a ground or reference is provided to reference electrodes 210 in the first region and the same driving signal 300 is provided to the remaining reference electrodes 210 in the second region 206. As a result, the piezoelectric material is only activated in first region 204.Inventor: Manders et al

[0086] During a second step during transmit, switching circuits 120 are configured to selectively connect one of channels 126, corresponding to reference or ground, to one or more channels 122 corresponding to one or more first electrodes 210 in second region 206. In embodiments, channels 122 are selected corresponding to all of first electrodes 210 in second region 206. Switching circuits 120 are further configured to selectively connect to a different one or more channels 126, carrying a driving signal 300, to the remaining channels 122, corresponding to one or more first electrodes 210 in first region 204. In this manner, a voltage differential proportional to driving signals 300 is present only across each of the plurality of second electrodes 212 in second region 206, since a ground or reference is provided to first electrodes 210 in the second region 206 and the same driving signal 300 is provided to the remaining first electrodes 210 in first region 204. As a result, the piezoelectric material is only activated in second region 206. As a result, during a transmit step, ultrasound signals are selectively emitted from either one of the first region 204 and second region 206.

[0087] In embodiments, switching circuits 120’ selectively connect one or more second electrodes 212 in the first region or one or more second electrodes 212 in the second region 206 during any of the transmit or receive steps, such that ultrasound signals are selectively emitted or received from one of the first region 204 or the second region 206.

[0088] During a receive step, control circuits 132 further configure switching circuits 120 to interconnect at least one of the plurality of channels 126, for example, comprising a channel corresponding to a reference or ground, to one or more of the plurality of channels 122. As a non-limiting example, channels 122 are selected such that first electrodes 210 in first region 204 are selected. As a further non-limiting example, channels 122 are selected such that first electrodes 210 in second region 206 are selected. In embodiments, one or more of the plurality of channels 122 are connected to a high impedance channel, to deactivate transducer regions for the corresponding first electrodes 210 coupled to said channels 122. Received signals 310 are detected by circuits 14, for example, by MUX / deMUX 82, across one or more of the plurality of transducer elements defined by signal electrodes 212 and selected first electrodes 210.

[0089] In embodiments, a first subset of the plurality of channels 126 are coupled to the plurality of channels 122, and a second subset of the plurality of channels 126 are connected to the plurality of channels 124. The switching and control logic described above is performed by circuits 14, for example by one or more of a processor 38 and FPGA 84, such that drivingInventor: Manders et alsignals 300 are delivered to the plurality of first electrodes 210 and plurality of second electrodes 212, and received signals 310 are received therefrom, as described.

[0090] In yet a further embodiment, blended transducer array 200 is used to concurrently emit multiple ultrasound wavefronts from a plurality of transducer regions 204, 206 of transducer array 200. During a transmit step, a first subset of the plurality of channels 126, for example, comprising channels carrying driving signals 300, are selectively coupled to the plurality of signal channels 124, in turn connected to the plurality of second electrodes 212. A second subset of channels 126, corresponding to a reference signal or ground, are selectively coupled to one or more channels 122 corresponding to one or more first electrodes 210 in first region 204 and one or more first electrodes 210 in second region 206. In embodiments, channels 122 are selected corresponding to all of first electrodes 210 in first region 204 and all of first electrodes 210 in first region 206. In this manner, a voltage differential proportional to driving signals 300 is present across the plurality of second electrodes 212 in first region 204 and second region 206. As a result, the piezoelectric material is activated in both the first region 204 and the second region 206. In embodiments, switching circuits 120 are configured to selectively interconnect the plurality of channels 126 to the plurality of channels 122 and channels 124, as described. In embodiments, control circuits 132 are configured to control switching circuits 120.

[0091] During a first receive step, a first subset of the plurality of channels 122 coupled to first electrodes 210 corresponding to one of a plurality of transducer regions, are selectively coupled to at least one of the plurality of channels 126, for example, comprising a channel corresponding to a reference or ground. In embodiments, the remaining channels 122 not included in the first subset are selectively coupled to a high impedance channel, to deactivate transducer regions for the corresponding remaining first electrodes 210 coupled to said remaining channels 122. As a non-limiting example, channels 122 are selected such that first electrodes 210 in first region 204 are selected. A first subset of differential received signals 310 are detected by circuits 14, for example, by MUX / deMUX 82, across one or more of the plurality of transducer elements defined by signal electrodes 212 and selected first subset of first electrodes 210, corresponding to one of a the plurality of transducer regions.

[0092] During a subsequent receive step, a second subset of the plurality of channels 122 coupled to first electrodes 210 corresponding to another one of the plurality of transducer regions, are selectively coupled to at least one of the plurality of channels 126, for example, comprising a channel corresponding to a reference or ground. In embodiments, the remainingInventor: Manders et alchannels 122 not included in the second subset are selectively coupled to a high impedance channel, to deactivate transducer regions for the corresponding remaining first electrodes 210 coupled to said remaining channels 122. A second subset of differential received signals 310 are detected by circuits 14, for example, by MUX / deMUX 82, across one or more of the plurality of transducer elements defined by signal electrodes 212 and selected second subset of first electrodes 210. As a non-limiting example, the second subset of channels 122 are selected such that the second subset of first electrodes 210 corresponds to second region 206. This process may be repeated for each of the plurality of transducer regions.

[0093] In this manner, ultrasound waves are concurrently emitted from all regions of a blended transducer array 200, and received ultrasound waves are detected separately at each region of said blended transducer array 200.

[0094] FIG. 13A and 13B is a flowchart of an example process 600, for use of a blended transducer array 200 and imaging device 10, as described herein. In some implementations, one or more process blocks of FIG. 13A and 13B may be performed by a device.

[0095] As shown in FIG. 13A and 13B, process 600 may include selectively coupling the plurality of signal electrodes to driving and receive circuits, for providing a first signal to the selectively coupled plurality of signal electrodes (block 602). As also shown in FIG. 13A and 13B, process 600 may include selectively coupling the plurality of reference electrodes, which are perpendicular to the plurality of signal electrodes, to the driving and receive circuits for providing a reference signal to the selectively coupled plurality of reference electrodes (block 604). As further shown in FIG. 13A and 13B, process 600 may include applying a differential signal across the selectively coupled plurality of reference electrodes and the plurality of signal electrodes, to generate one or more ultrasound waves from a plurality of ultrasound transducer regions (block 606). As also shown in FIG. 13A and 13B, process 600 may include selectively coupling a subset of the plurality of reference electrodes to the driving and receive circuits, the subset corresponding to one of a plurality of transducer regions, for providing a reference channel (block 608). As further shown in FIG. 13A and 13B, process 600 may include selectively coupling the plurality of signal electrodes to the driving and receive circuits, for providing a plurality of signal channels (block 610). As also shown in FIG. 13A and 13B, process 600 may include receiving ultrasound wave reflections and detecting one or more differential signals across the plurality of signal channels and the reference channel, to form raw ultrasound data from one of the plurality of transducer regions (block 612). As further shown in FIG. 13A and 13B, process 600 may include repeating steps in blocks 608 throughInventor: Manders et al612 for different subsets of the plurality of reference electrodes corresponding to different ones of the plurality of transducer regions (block 614). As further shown in FIG. 13A and 13B, process 600 may include processing the raw ultrasound data to form imaging data of the manufactured part (block 616).

[0096] Although FIG. 13A and 13B shows example blocks of process 600, in some implementations, process 600 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in FIG. 13A and 13B. Additionally, or alternatively, two or more of the blocks of process 600 may be performed in parallel.

[0097] The described transducer arrays offer several benefits, which will be clear to experts in the field. They enable active focusing on an elevational plane without needing duplicate driving circuitry. Additionally, achieving the desired results requires much simpler components compared to existing alternatives, such as use of two-dimensional arrays. A blended transducer array also emits ultrasound wavefronts at various angles, enhancing the detection of different target features through diverse emitted and received waves, such as internal surface reflections and crack detection from angled reflections.

[0098] The quantification of wall loss, including the accurate quantification of cracks, is important to determine the structural integrity of a tubular or pipeline, such as by calculating the burst pressure a wellbore tubular or pipeline, which depends on accurate values of wall thickness. If the material is assumed to be homogeneous and isotropic, and the stress distribution is uniform, burst pressure is calculated using Barlow's formula, given by P = (2 * S * t) / D, where P is the burst pressure, S is the material's yield strength, t is the wall thickness of the tubular or pipeline, and D is the outer diameter. A conservative calculation of burst pressure can be obtained using the River Bottom Method, to account for potential defects such as corrosion or wall thinning, which modifies Barlow's standard formula by incorporating a correction factor to account for these imperfections by using the effective wall thickness, which reduces wall thickness by the depth of the deepest defect or corrosion pit. Finite element analysis can also be used to calculate burst pressure, where a detailed geometric configuration! of the wellbore tubular or pipeline is generated, which is then discretized into a finite element mesh consisting of numerous small, interconnected elements. Accurate values for wall thickness are critical for obtaining accurate simulated results, especially in cases involving complex geometries, material inhomogeneities, or localized defects. Determining burst pressure is critically important as it ensures the structural integrity and safety of the wellbore tubular or pipeline under operational pressures, especially in environments whereInventor: Manders et alcorrosion and other forms of degradation are prevalent. Accurate burst pressure calculations help prevent catastrophic failures, environmental hazards, and costly downtimes by ensuring that the materials and design specifications can withstand the maximum internal pressures they will encounter during their service life.

[0099] It will be appreciated that data processing may be performed with plural processors: on the device, at the operations site, and optionally on a remote computer. The term ‘processor’ is intended to include computer processors, cloud processors, microcontrollers, firmware, GPUs, FPGAs, and electrical circuits that manipulate analogue or digital signals. While it can be convenient to process data as described herein, using software on a general computer, many of the steps could be implemented with purpose-built circuits.

[0100] It will be appreciated that the various memories discussed may be implemented as one or more memory units. Non-volatile memory is used to store the compressed data and instructions so that the device can function without continuous power. Volatile memory (RAM and cache) may be used to temporarily hold raw data and intermediate computations. Additionally or alternatively, the compressed images may be transmitted over a telemetry unit of the device to a corresponding telemetry unit of the surface computer system.

[0101] Terms such as “top”, “bottom”, “distal”, “proximate” “downhole”, “uphole”, “below,” “above,” “upper, downstream,” are used herein for simplicity in describing relative positioning of elements of the conduit or device, as depicted in the drawings or with reference to the surface datum. Although the present methods, systems and devices have been described and illustrated with respect to preferred embodiments and preferred uses thereof, it is not to be so limited since modifications and changes can be made therein which are within the full, intended scope as understood by those skilled in the art.

[0102] While many specific details have been provided for a thorough and complete understanding of the embodiments as described herein, it will be understood by those of ordinary skill in the art that said embodiments can be practiced even without these specific details. In other instances, detailed descriptions of components, methods and procedures have not been provided to avoid obscuring the relevant features being described. Further, the embodiments described herein should not be considered as limiting the scope of the method, system and devices as recited in the claims.

Claims

Inventor: Manders et alCLAIMS:

1. An acoustic imaging system for inspecting manufactured parts, the acoustic imaging system comprising:an ultrasonic transducer array comprising:a first array of signal electrodes on a first surface of a piezoelectric material forming a plurality of ultrasonic transducer elements defining the ultrasonic transducer array along a first direction; anda second array of reference electrodes on a second surface of the piezoelectric material opposite the first surface, the second array formed along a second direction, orthogonal to the first direction, each of the reference electrodes further defining each of the plurality of ultrasonic transducer elements; andcoupling circuits selectively defining a first configuration and a second configuration;wherein the first configuration is defined by coupling:(a) one or more of the signal electrodes to one or more of the reference electrodes;(b) remaining uncoupled reference electrodes to one of a reference channel and a high impedance channel; and(c) the signal electrodes to signal channels,to sequentially provide differential driving signals across the signal electrodes and the remaining uncoupled reference electrodes to emit one or more ultrasound wavefronts with an elevational focus depth on a passive plane of the ultrasonic transducer array; and wherein the second configuration is defined by coupling:(d) the reference electrodes to each other;(e) the reference electrodes to a reference channel; and(f) the signal electrodes to signal channels,to detect differential received signals across each of the signal electrodes and the reference electrodes.Inventor: Manders et al2. The acoustic imaging system according to claim 1 , wherein an elevational focus depth of the one or more ultrasound wavefronts is based on a distance to a surface of a manufactured part.

3. The acoustic imaging system according to claim 1 , wherein a number of signal electrodes is greater than a number of reference electrodes.

4. The acoustic imaging system according to claim 3, wherein the number of signal electrodes comprises between 128 to 1024 electrodes and the number of reference electrodes comprises between 2 and 25 electrodes.

5. The acoustic imaging system according to claim 1 , further comprising control circuits for controlling the coupling circuits.

6. The acoustic imaging system according to claim 1 , wherein the reference electrodes are arranged as symmetrically opposing pairs of reference electrodes arranged around a central second electrode.

7. The acoustic imaging system according to claim 6, wherein each of the symmetrically opposing pairs of reference electrodes are coupled.

8. The acoustic imaging system according to claim 1 , wherein a height of each of the signal electrodes is equal to a total width of the second array of reference electrodes.

9. The acoustic imaging system according to claim 1 , wherein a height of each of the reference electrodes is equal to a total width of the first array of signal electrodes.

10. A method for imaging a manufactured part using the acoustic imaging system of claim 1 , comprising the steps of:a) selectively coupling, by the coupling circuits, at least one reference electrode to one of a reference channel and a high impedance channel;b) selectively coupling, by the coupling circuits, a remainder of the reference electrodes to one of the signal electrodes;c) selectively coupling, by the coupling circuits, the signal electrodes to signal channels;d) providing a differential driving signal across the selectively coupled at least one reference electrode and the signal electrodes;Inventor: Manders et ale) repeating a) to d) for different at least one reference electrodes, to cause the ultrasonic transducer array to emit ultrasound waves focused on an elevational plane;f) selectively coupling, by the coupling circuits, the reference electrodes to a reference channel;g) receiving ultrasound wave reflections and detecting differential received signals across the signal electrodes and the reference electrodes, to generate received ultrasound signals; andh) beamforming the received ultrasound signals to form elevational focused imaging data of the manufactured part.

11. The method according to claim 10, wherein e) further comprises applying transmit delays to the differential driving signals for the different at least one reference electrodes.

12. The method according to claim 10, wherein the least one reference electrode in a) further comprises an opposing pair of reference electrodes.

13. An acoustic imaging system for inspecting manufactured parts, the acoustic imaging system comprising:a first ultrasonic transducer array comprising a first plurality of transducer elements formed by an array of first signal electrodes, a first reference electrode and a first piezoelectric material therebetween, the first ultrasonic transducer array for emitting an ultrasound wavefront in a first direction;a second ultrasonic transducer array comprising a second plurality of transducer elements formed by an array of second signal electrodes, a second reference electrode and a second piezoelectric material therebetween, each of the second signal electrodes electrically coupled to corresponding each of the first signal electrodes, the second ultrasonic transducer array for emitting an ultrasound wavefront in a second direction; andcoupling circuits selectively defining a first configuration, a second configuration and a third configuration;wherein a first configuration is defined by coupling:Inventor: Manders et al(a) the first reference electrode and the second reference electrode to a reference channel: and(b) the first signal electrodes and the second signal electrodes to signal channels,to provide differential driving signals to the first plurality of transducer elements to emit ultrasound wavefronts in a first direction and to the second plurality of transducer elements to emit ultrasound wavefronts in a second direction; wherein a second configuration is defined by coupling:(c) the first reference electrode to a reference channel(d) the second reference electrode to a high impedance channel; and(e) the first signal electrodes to signal channels,to detect first received signals from the first plurality of transducer elements; andwherein a third configuration is defined by coupling:(f) the second reference electrode to a reference channel;(g) the first reference electrode to a high impedance channel; and (h) the second signal electrodes to signal channels,to detect second received signals from the second plurality of transducer elements.

14. The acoustic imaging system according to claim 13, wherein a shape of the first piezoelectric material is different to a shape of the second piezoelectric material.

15. The acoustic imaging system according to claim 13, wherein the reference channel is electrical ground.

16. The acoustic imaging system according to claim 13, wherein the first ultrasonic transducer array is formed on a first surface, the second ultrasonic transducer array is formed on a second surface, and said second surface is adjustable with respect to said first surface.Inventor: Manders et al17. A method for imaging a manufactured part using the acoustic imaging system of claim 13, comprising the steps of:a) selectively coupling, by the coupling circuits, the first reference electrode and the second reference electrode to a reference channel;b) selectively coupling, by the coupling circuits, the first signal electrodes and the second signal electrodes to signal channels;c) providing differential driving signals to the first plurality of transducer elements and to the second plurality of transducer elements, to emit ultrasound waves in a first direction from the first ultrasonic transducer array and in a second direction from the second ultrasonic transducer array;d) selectively coupling, by the coupling circuits, the second reference electrode to a high impedance channel;e) receiving first ultrasound wave reflections during a first receive window and detecting first differential received signals across the first plurality of transducer elements, to generate first received ultrasound signals;f) selectively coupling, by the coupling circuits, the first reference electrode to a high impedance channel and the second reference electrode to a reference channel;g) receiving second ultrasound wave reflections during a second receive window and detecting second differential received signals across the second plurality of transducer elements, to generate second received ultrasound signals; and h) beamforming the first received ultrasound signals and the second received ultrasound signals to form imaging data of the manufactured part.

18. The method according to claim 17, wherein c) further comprises applying transmit delays to the differential driving signals, to emit steered ultrasound waves.

19. The method according to claim 17, wherein beamforming the first received ultrasound signals forms a first imaging frame of the manufactured part and beamforming the second received ultrasound signals forms a second imaging frame of the manufactured part.Inventor: Manders et al20. The method according to claim 19, wherein beamforming parameters for beamforming the first received ultrasound signals are different to beamforming parameters for beamforming the second received ultrasound signals.

21. The method according to claim 17, wherein a time defining the first receive window is based on one or more of a stand-off distance of the first ultrasonic transducer array to a surface of the manufactured part and a manufactured part thickness.

22. The method according to claim 17, wherein a time defining the second receive window is based on one or more of a stand-off distance of the second ultrasonic transducer array to a surface of the manufactured part, a manufactured part thickness and an angle between the second ultrasonic transducer array and a surface of the manufactured part.

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