Mixed array imaging probe

Abstract

An apparatus for imaging an object and a process for manufacturing the apparatus are provided. The apparatus comprises a housing and a distal section. The distal section includes an acoustic subarray on a first substrate configured to transmit acoustic signals toward the object. The distal section includes an optical subarray on a second substrate configured to detect acoustic signals from the object. The distal section includes an input / output (I / O) region including one or more optical I / O channels. The one or more optical I / O channels are configured to refract optical signals between the optical subarray and the one or more optical I / O channels.

Description

[Technical Field]

[0001]

[0001] This disclosure relates to optical sensing and is not limited to the design and packaging of photoacoustic mixed ultrasonic imaging probes.

[0002]

[0002] Acoustic or ultrasonic imaging techniques are used in a variety of industries, particularly in non-invasive measurement, remote sensing, and medical imaging. Acoustic imaging techniques work by transmitting an acoustic signal towards an object and detecting the echo signal reflected or generated from the object in response to the transmitted acoustic signal. Ultrasound, a type of non-ionizing radiation, has the advantage of non-invasive imaging. By transmitting sound waves of higher frequencies, the resolution of ultrasound is improved. However, the depth of penetration decreases due to increased acoustic attenuation. The trade-off between resolution and penetration depth becomes a challenge.

[0003]

[0003] Conventional ultrasound imaging probes consist of a cable, a cable strain relief, a proximal ergonomic housing, a distal nosepiece, and a transducer for transmitting and receiving acoustic signals, which are processed to generate images.

[0004]

[0004] Various known ultrasonic transducers used for imaging have numerous drawbacks. For example, some ultrasonic transducers are made from piezoelectric materials such as lead zirconate titanate (PZT), polymer thick film (PTF), and polyvinylidene fluoride (PVDF). However, challenges associated with using the piezoelectric properties of these materials include high operating voltage requirements, high electric field requirements (which can cause breakdown or failure), nonlinear responses with high hysteresis, and limitations on the detection angle. The bandwidth of these materials is also limited. A 6 dB bandwidth of PZT material generally only reaches about 70% bandwidth. Certain composite PZT materials offer a slight increase in bandwidth, but still only achieve a maximum of about 80% bandwidth. As another example, single-crystal materials are increasingly being used to improve the performance of ultrasonic probes, but single-crystal materials have the problem of having a low Curie temperature and being brittle. Another type of transducer material is silicon, which can be processed to construct capacitively machined ultrasonic transducer (CMUT) probes that can expand bandwidth. However, the sensitivity and reliability of CMUT probes are not very high. Furthermore, CMUT probes have various operational limitations. For example, because CMUT probes are nonlinear transducers, they are generally not suitable for harmonic imaging. In addition, an additional bias voltage is required for CMUT probes to operate properly. Therefore, there is a need for novel and improved devices and methods for ultrasonic sensing. [Overview of the project] [Means for solving the problem]

[0005]

[0005] Various examples and embodiments of mixed array probes are described. These descriptive examples are given not to limit or define the scope of this disclosure, but rather to illustrate examples to aid understanding. Specific examples are described in the detailed description. Further examination of this specification may provide a better understanding of the advantages offered by the various examples. [Brief explanation of the drawing]

[0006]

[0006] The accompanying drawings incorporated herein and forming part thereof illustrate one or more specific examples, which, together with the descriptions of the examples, are useful in illustrating the principles and implementations of those specific examples.

[0007] [Figure 1A] A fluoroscopic view of the ultrasound imaging probe according to this disclosure is shown. [Figure 1B] Figure 1A shows an exemplary internal mixing array in an exemplary ultrasound imaging probe. [Figure 1C] This is a block diagram showing an example of a mixed array in an ultrasound imaging probe. [Figure 1D] Figure 1A shows a portion of the mixed array support structure of an exemplary ultrasound imaging probe. [Figure 1E] Another diagram of the mixed array support structure for the exemplary ultrasound imaging probe shown in Figure 1A is presented. [Figure 2A] This is an example of an optical I / O design based on mirror coating with an interposer chip. [Figure 2B] This is an example of an optical I / O design based on a linear fiber array. [Figure 2C] This is an example of an optical I / O design based on a vertical interposer chip with a linear fiber array. [Figure 2D] This is an example of an optical I / O design based on a vertical interposer chip with a mirror structure. [Figure 2E] This is an example of an optical I / O design based on mirror coating without an interposer chip. [Figure 2F] This is an example of an optical I / O design based on an interposer chip connected to a fiber array. [Figure 3] Another diagram of Figures 2A and 2E, with added details, is shown according to one embodiment. [Figure 4] Figure 2D is another diagram showing an angle-polished interposer with a mirror coating according to one embodiment. [Figure 5]Another view of FIG. 2B showing a multi-core fiber in a 2D surface coupler array and a fiber array according to one embodiment. [Figure 6A] A view of a reflective focusing right-angle optical fixture according to one embodiment. [Figure 6B] An example of a manufacturing process of the reflective focusing right-angle optical fixture of FIG. 6A according to one embodiment. [Figure 7] A view of a refractive focusing right-angle optical fixture including a lens plate according to one embodiment. [Figure 8] A view of a design based on photonics wire bonding technology in a probe according to another embodiment. [Figure 9A] An example of an electrical I / O design including a 1D pad array for wire bonding a PIC chip and an FPC. [Figure 9B] Another example of an electrical I / O design including a 1D pad array for wire bonding a PIC chip and an FPC. [Figure 9C] Yet another example of an electrical I / O design including a 1D pad array for wire bonding a PIC chip and an FPC. [Figure 9D] An example of an electrical I / O design including a 2D pad array for flip-chip bonding a PIC chip and an FPC. [Figure 9E] Another example of an electrical I / O design including a 2D pad array for flip-chip bonding a PIC chip and an FPC. [Figure 9F] Another example of an electrical I / O design including a 2D pad array for flip-chip bonding a PIC chip and an FPC. [Figure 10A] A view showing the design of an AEG module according to one embodiment. [Figure 10B] A view showing the conventional design of an AEG module according to one embodiment. [Figure 10C] A view showing the manufacturing of an AEG module according to one embodiment. <00​This figure shows a conventional method for manufacturing an AEG module according to one embodiment. [Figure 11] This shows a double dicing process according to one embodiment. [Figure 12] This document presents an alternative design for a PIC module package according to one embodiment. [Figure 13] This shows a design for a conical nosepiece according to one embodiment. [Figure 14] An alternative design for a mixed ultrasound imaging probe according to one embodiment is shown. [Figure 15A] This is a schematic diagram of a modularized optical subarray arranged in a stepped pattern with individual backing blocks, according to one embodiment. [Figure 15B] This is a schematic diagram of a modularized optical subarray arranged in a stepped manner, sharing an integrated backing block embedded in a thermomechanical substrate, according to one embodiment. [Figure 15C] This is a schematic diagram of a modularized optical subarray arranged in a polygonal pattern with individual backing blocks, according to one embodiment.

[0008]

[0042] Throughout the attached drawings, similar reference letters consistently indicate the corresponding features. [Modes for carrying out the invention]

[0009]

[0043] Here, various structures are described according to their geometric properties. As described herein, the structures described may differ from the shapes described, depending on the tolerances of known manufacturing techniques. Unless otherwise specified, features described using the term "substantially" should be understood to be within 5% of the exactness. For example, a feature described as "substantially parallel" may deviate by 5% from actual parallelism.

[0010]

[0044] Ultrasound or acoustic imaging, a type of non-ionizing radiation, is used in a variety of industries, particularly in non-invasive measurement, remote sensing, medical imaging, diagnostic procedures, surgical procedures, and therapeutic procedures, due to its non-invasive imaging properties. In medical imaging diagnostic, surgical, and therapeutic applications, clinicians use ultrasound to image the internal structures of patients (including tissues, organs, bones, other anatomical structures, implants, medical devices, or other objects within the ultrasound-irradiated area).

[0011]

[0045] Some existing imaging technologies utilize acoustic energy generation (AEG) materials as transducers for generating and receiving acoustic signals. Commonly used AEG transducers include many materials well-known to engineers in this field, such as piezoelectric materials, e.g., lead zirconate titanate (PZT), ceramics, piezoelectric single crystals (PIN-PT, PIN-PMN-PT, etc.), polymer thick films (PTF), polyvinylidene fluoride (PVDF), capacitive micromachine ultrasonic transducers (CMUTs), photoacoustic transducers, and piezoelectric micromachine ultrasonic transducers (PMUTs). However, challenges associated with the use of these materials include high operating voltage requirements, high electric field requirements (which can cause damage or failure), nonlinear responses with high hysteresis, and limitations on the detection angle, in addition to the trade-off between resolution and penetration depth. Furthermore, the detection sensitivity of AEG transducers is size-dependent, limiting their suitability for size-constrained applications such as intravascular ultrasound (IVUS) devices.

[0012]

[0046] Another challenge is the narrow bandwidth of AEG transducers. For example, in the case of ultrasonic transducers made from piezoelectric materials such as lead zirconate titanate (PZT), the 6dB bandwidth of PZT is typically limited to about 70%. Certain composite PZT materials slightly increase the bandwidth, but even then, the bandwidth that can be achieved is still only about 80% at most. As another example, single-crystal materials are increasingly being used to improve the performance of ultrasonic probes, but they have problems with low Curie temperature and brittleness. Another type of transducer material is silicon, which can be processed to create capacitive micromachine ultrasonic transducer (CMUT) probes that can expand the bandwidth. However, CMUT probes are not very sensitive or reliable. Furthermore, CMUT probes have several operational limitations. For example, because CMUT probes are nonlinear transducers, they are generally not suitable for harmonic imaging. In addition, CMUT probes require an additional bias voltage to operate properly. Furthermore, some AEG transducers and systems can be affected by electromagnetic interference caused by ablation instruments, cauterization instruments, or other procedures and techniques that apply electrical energy to tissue. Furthermore, the use of electromechanical transducers at the distal end may involve conductive lines and associated components, necessitating additional design and safety requirements and challenges. Therefore, novel and improved devices and methods are needed for ultrasonic imaging modes with harmonics of various frequencies to obtain higher resolution, superior penetration, and less artifacts than the basic images of conventional ultrasonic sensing.

[0013]

[0047] Photonic devices and optical pressure detection techniques offer significant potential in ultrasonic detection. In photonic devices, refractive index modulation and / or shape deformation due to distortion induced by sound waves are converted into changes in the intensity of detected light and the spectral characteristics of the device. In existing devices, optical resonators are used as highly sensitive ultrasonic detectors. Generally, the performance of an optical resonator is limited by its quality factor Q (i.e., a higher Q results in lower optical loss and a smaller detectable resonance shift), the optical insertion loss across the optical path, and the acousto-optic and mechanical properties of the materials constituting the resonator. Optical sensors such as interference-based optical sensors, optical resonators, and interferometers can offer higher sensitivity, wider bandwidth, and wider acceptance angles in receiving ultrasonic signals compared to other types of ultrasonic sensors. Because optical sensors are highly sensitive, have wide bandwidths, and wide acceptance angles, the images produced by optical sensors can have improved spatial resolution, penetration depth, signal-to-noise ratio (SNR), tissue harmonic imaging, and / or Doppler sensitivity.

[0014]

[0048] Optical sensors are coupled to light sources to transmit light and can be practically useful (e.g., in ultrasonic imaging and other conversion applications in acousto-optic systems). Acousto-optic systems based on optical sensors may directly measure ultrasound through photoelastic effects and / or physical deformation of the resonator in response to ultrasound (e.g., ultrasonic echoes). For example, in the presence of ultrasonic (or other pressure) waves, the transmitted or reflected spectrum of an optical resonator may undergo spectral shifts caused by changes in the refractive index and shape of the optical resonator. Spectral changes can be monitored and analyzed by the light transmission intensity between the spectral region and the optical resonator. Furthermore, by monitoring and analyzing transmitted or reflected light between multiple optical resonators, additional spatial and other information can be derived. In addition, other physical parameters such as temperature and pressure may affect the transmitted light, providing additional information to support multidimensional sensing. However, for shape factors used in ultrasonic imaging, there are challenges in designing robust sensors with minimal optical insertion loss across the entire optical path and an acceptable Q value.

[0015]

[0049] In some configurations, multiple transducer types are used. In some examples, the ultrasonic array may contain elements of the same type. Alternatively, the ultrasonic array may contain elements of different types. For example, the probe may contain one or more AEG transducers, such as piezoelectric transducers, PZT transducers, PTF transducers, PVDF transducers, CMUTs, PMUTs, photoacoustic transducers, transducers based on single crystal materials (e.g., LiNbO3(LN), Pb(Mg113Nb213)-PbTiQ3(PMN-PT), and Pb(In112Nb112)-Pb(Mg113Nb213)PbTiQ3(PIN-PMN-PT)), or combinations thereof.

[0016]

[0050] Furthermore, in some examples, the ultrasonic array may include one or more optical sensors, for example, interference-based optical sensors which may be one or more optical interferometers and / or optical resonators, or a sensor array for beamforming to construct high-quality ultrasonic images of an object or region of interest, as described above. Optical resonators may have higher sensitivity, wider bandwidth, and wider reception angles in receiving ultrasonic signals compared to other types of ultrasonic sensors. One or more array elements of the first type (e.g., AEG transducers) may be used to form a first image. In parallel, one or more array elements of the second type (e.g., optical sensors) may be used to detect acoustic signals that can be used to form a second image. The second image produced by these highly sensitive, wideband optical sensors may be used independently or combined with the first image to form an even more improved image. In some configurations, the optical sensors can be used independently of the transmitting element or transmitting array. In diagnostic and therapeutic procedures, additional information from signals sensed beyond the image may be used, such as when used for multidimensional sensing.

[0017]

[0051] Optical sensors may perform multidimensional sensing (e.g., measuring multiple different physical signals nearly simultaneously in real time or near real time). Optical sensor systems generally include one or more optical sensors, and optical sensors (e.g., a single sensor) may be used to detect multiple physical signals such as temperature, pressure, and sound waves by analyzing sensor responses such as mode shift (e.g., changes in frequency, depth, and spectral response shape), baseline drift, mode splitting, and mode spread.

[0018]

[0052] Sensor signals can be used to generate multiple measurement signals corresponding to multiple physical signals. A multidimensional sensor is capable of measuring multiple physical signals. Therefore, an array may include multiple optical sensors, but one or more optical sensors within the array may function independently of the other optical sensors in the array.

[0019]

[0053] This disclosure relates generally to the field of ultrasound, and more particularly to methods and devices that enable ultrasonic conversion using a mixed array, including, for example, integrating an array of optical sensors and other transducers.

[0020]

[0054] In general, in some embodiments, an apparatus for imaging an object may include an ultrasonic transducer array comprising one or more array elements of a first type and one or more array elements of a second type distinct from the first type. The first type may be a transducer configured to transmit sound waves (e.g., a piezoelectric transducer or an AEG material including a CMUT), and the second type may be an optical sensor (e.g., an interference-based optical sensor such as an optical resonator or an optical interferometer). The array elements of the first and second types are configured to detect acoustic echoes corresponding to transmitted sound waves. Alternatively, the array elements of the first type may be configured solely to transmit sound waves.

[0021]

[0055] The following joint patent applications, namely U.S. Patent Application No. 17 / 832,507, filed June 3, 2022, title of invention "Whispering Gallery Mode Resonator for Sensing Applications", U.S. Patent Application No. 17 / 956,640, filed September 29, 2022, title of invention "Optical Microresonator Array Device for Ultrasonic Sensing", and U.S. Patent Application No. 18 / 091,073, filed December 29, 2022, invention The title of the invention is "Acousto-Optical Harmonic Imaging by Optical Sensors," U.S. Patent Application No. 17 / 990,596, filed November 18, 2022; the title of the invention is "Mixed Ultrasonic Transducer Array," U.S. Patent Application No. 17 / 244,605, filed April 29, 2021; the title of the invention is "Modularized Acoustic Probe," U.S. Patent Application No. 18 / 032,953, filed April 20, 2023; the title of the invention is "Image Synthesis of Mixed Ultrasonic Sensor Arrays." U.S. Patent Application No. 18 / 025,081, filed March 7, 2023, title of invention, "Synthetic Aperture Imaging System and Method Using a Mixed Array," U.S. Patent Application No. 18 / 091,073, filed December 29, 2022, title of invention, "Acousto-Optical Harmonic Imaging Using an Optical Sensor," PCT Application c, filed October 7, 2022, title of invention, "Visualization of Ultrasonic Beacons Using an Optical Sensor," PCT Application PCT / US2022 / 041252, filed August 23, 2022, title of invention, "Multidimensional Signal Detection Using an Optical Sensor," and U.S. Provisional Application No. 63 / 550,515, filed February 6, 2024, titled "Photonic Integrated Acoustic Sensor," disclose various methods and systems of optical sensors, mixed array transducers, ultrasonic beamforming, and image processing, the disclosures of which are incorporated by reference for any purpose.

[0022]

[0056] Figure 1A shows a perspective view of an ultrasound imaging probe according to this disclosure. Figure 1B shows an internal mixed array 150 within the exemplary probe of Figure 1A. Figure 1C is a block diagram 180 showing an example of a mixed array within an ultrasound imaging probe. Figure 1D shows a portion of the mixed array support structure of the exemplary ultrasound imaging probe of Figure 1A. Figure 1E shows another view of the mixed array support structure of the exemplary ultrasound imaging probe of Figure 1A.

[0023]

[0057] As shown in Figure 1A, the shape of an ultrasonic imaging probe can be described in three dimensions: lateral (L), upward (E), and axial (A). In some embodiments, the ultrasonic imaging probe includes a mixed array of AEG material subarrays and optical integrated circuit (PIC) receiving subarrays (abbreviated as optical subarrays), which are described in detail in Figures 1B and 1C. The front end of the probe that contacts the surface to be imaged may be largely occupied by an acoustic or imaging aperture 102 (e.g., the acoustic front stack in Figure 1C). The lateral length 104 of the acoustic aperture is typically determined by the AEG array parameters (number of elements, element width, element pitch, and gaps between AEG elements (e.g., kerf)). The upward dimension of the probe consists of the upward width 106 of the acoustic aperture, determined by the shape of the single-element transmitter, and the optical refraction space 108 required to accommodate the components of the optical sensor subarray, as will be described in more detail in some embodiments. The outer portion of the probe consists of a housing 110, a nosepiece 112, and a cable 114.

[0024]

[0058] Figure 1B is an enlarged cross-sectional view of a surface of the mixed array 150 showing the orientation of a specific optical array component. The mixed array 150 is shown as a linear array. The elements of the AEG subarray 152 and the optical subarray 154 form the basic components of the ultrasound probe transducer and sensor. The mixed array 150 may be characterized by a lateral pitch (e.g., a lateral pitch less than or equal to the acoustic wavelength in the tissue) determined by the constraints of the imaging application. w ) and increase (W ele The depth of focus is determined by the desired acoustic focus of the ultrasound probe. The acoustic focus (e.g., the focus of the rise dimension) can be applied to both the transmitting and receiving processes. The depth of focus is determined by the rise size (W ele Determined by the ) and / or acoustic lens. The lateral pitch of a single element is added together across the entire array, and the length L lat A lateral imaging aperture is formed, which at least partially determines the imaging performance of the array.

[0025]

[0059] Higher-dimensional arrays can be formed by combining multiple one-dimensional (1D) arrays. For example, an array can be configured to operate in a 1.25-dimensional (1.25D) array configuration, a 1.5-dimensional (1.5D) array configuration, a 1.75-dimensional (1.75D) array configuration, a two-dimensional (2D) array configuration, or other array configurations. Generally, the dimensions of an ultrasonic transducer array relate to the range of ascending beam width (or ascending beam slice thickness) achievable when imaging with the ultrasonic transducer array, and to the degree to which the system controls the ascending beam aperture size, focus, and / or steering across the entire imaging field (e.g., across the entire imaging depth) of the transducer array. A 1D array has one row of elements in the ascending dimension and a fixed ascending aperture size. A 1.25D array has multiple rows of elements in the ascending dimension and a variable ascending aperture size, but the ascending focus is fixed by an acoustic lens. A 1.5D array has multiple rows of elements in the rise dimension, a variable rise aperture size, and a variable rise focus controlled by electronic delay. A 1.75D array is a 1.5D array with additional rise beam steering capabilities. A 2D array has numerous elements in both the lateral and rise dimensions to meet the design constraint of minimum pitch for large beam steering angles. Arrays may have geometric or other shapes to accommodate various types of nonlinear probes, including, but not limited to, curved arrays, convex arrays, and / or phased arrays.

[0026]

[0060] As shown in Figure 1C, the AEG subarray 152 includes a PZT module 156, and the optical subarray 154 includes a PIC module 158. The AEG and optical subarrays 152 and 154 are mechanically supported and protected by a thermomechanical substrate and housing. The AEG subarray 152 can be mounted on a separate suitable substrate from the optical subarray substrate. Alternatively, the AEG subarray and the optical PIC subarray may be mounted on a single substrate. The PIC and AEG array modules may be formed as a single unit or may consist of multiple modules.

[0027]

[0061] The acoustic front stack 170 is located at the distal end of the probe and includes an acoustic stack 172 and an optical stack 174. The acoustic front stack 170 also includes an interface layer 182 that contacts the surface of the area being imaged and transmits acoustic signals between the probe and the object being imaged. The interface layer may be formed separately from the acoustic stack 172 and / or the optical stack 174, or as a component thereof. The optical stack 174 may be located behind or inside the interface layer 182. The interface layer 182 can be fabricated from a biocompatible material having minimal acoustic impedance and can also function as a moisture barrier and electrical insulator. In some embodiments, an electrically insulating and chemical-resistant layer (e.g., parylene) may be placed between the outer surface of the interface layer 182 and the AEG subarray 152 to ensure electrical safety. In some embodiments, the interface layer 182 may be a single integrated component of multiple different materials, or a single integrated component of a single material. The interface layer 182 may include acoustic lenses, acoustic windows, sealing layers, and adhesive layers, etc.

[0028]

[0062] The interface layer 182 is further mounted on an acoustic matching layer selected for acoustic impedance matching with the target environment, which can reduce acoustic reflections at the interface between the mixed array and the target environment. As shown in Figure 1C, in one embodiment, each subarray has its own matching layer, with matching layer ML-P184a on the AEG subarray 152 and matching layer ML-O184b on the optical subarray 154. In some embodiments, the optical subarray 154 may not require a matching layer due to the acoustic impedance of the materials constituting the optical sensor.

[0029]

[0063] In embodiments, the interface layer 182 may be further configured to include one or more acoustic lenses to assist in focusing / steering the transmitted acoustic signal and collimating the wavefront of the received acoustic signal. The acoustic lenses are used to focus the ultrasound beam onto a plane perpendicular to the image plane or axial elevation plane. Acoustic lenses are typically made of materials with acoustic impedances similar to those of human tissue. The specific shape allows the lens to provide an appropriate slice thickness, resulting in uniform sensitivity and improved SNR across the entire field of view. Room temperature vulcanized (RTV) silicon is a typical acoustic lens material because the sub-millimeter RTV layer provides excellent electrical and moisture insulation and also offers sufficient durability as a contact surface between the transducer and the patient. In some embodiments, parylene, which is an electrically insulating and chemically resistant layer, may be placed between the lens and the AEG element to ensure electrical safety. With the nosepiece 112 attached, the acoustic lens can be directly overmolded onto the acoustic stack 172 and / or optical stack 174. The lens thickness can be controlled using precision fixtures, and the potential tolerance stack of individual components can be designed before the precision fixture process. The acoustic lens, in addition to the interface layer and / or parylene layer, can hermetically seal the acoustic window or aperture 102 within the nose cone of the nosepiece 112.

[0030]

[0064] It should be noted that the acoustic front stack and optical sub-array 154 in front of the AEG sub-array 152 may include different stacks, known as a mixed acoustic front stack. In some embodiments, due to the transducer design or mechanical interface with other components, an axial offset exists between the optical receiving surface (e.g., the top of ML-O184b) and the AEG surface (e.g., the top of ML-P184a). The offset can be filled by introducing an acoustic window (e.g., a flexible or rigid elastomer, with or without matching layers on the top and bottom) made of a material with low acoustic attenuation and good acoustic matching with the upper and lower layers. In some embodiments, optical receivers with small rise size (<1 mm) do not necessarily require an acoustic lens. In either case, a cast RTV layer can be introduced in the top finish, and its shape can be designed to function as an acoustic lens as needed. The design of the mixed acoustic front stack may follow one or more of the following: (1) The top finish of the acoustic stack can be a smooth shape without concave surfaces, with sufficient electrical and moisture shielding and durability. (2) The acoustic front stack does not cause significant acoustic attenuation in any of the target acoustic frequency bands.

[0031]

[0065] The interface layer 182 may also include a couplant made of a low-attenuation, impedance-matched material such as a flexible or rigid elastomer. The interface layer 182 may be a single or multiple component attached via adhesive, and / or molded in place on the AEG and optical sensor array. In some embodiments, the interface layer 182 may be located within or as part of the transducer housing as an outer layer of the transducer device between the AEG and optical sensor array and the ambient environment. Furthermore, the interface layer 182 protects the optical sensors.

[0032]

[0066] The matching layer (ML) (e.g., ML-P184a and ML-O184b) connects the interface layer 182 to the PZT array module forming the acoustic stack 172 and the PIC array module forming the optical stack 174, which are electrically and / or optically connected to the cable 114 via an electrical board, optical links, and a cable tension relief section at the rear of the probe. In some embodiments, the matching layer may be optional if the loss of acoustic power reaching the AEG receiver and / or optical sensor is acceptable. In this way, the potential bandwidth limitations posed by the matching layer can be eliminated. Inside the probe, the electrical link 186, also called the electrical I / O channel, is implemented by a flexible printed circuit (FPC), and the optical link, also called the optical I / O channel, can be implemented by an optical fiber, an interposer chip, a printed optical waveguide, etc. The PZT module 156 and PIC module 158 are mounted directly to a backing block (such as BB-P190a or BB-O190b), providing mechanical support to the modules, and (1) the PIC module 158 and / or PZT module 156 can function as acoustic absorbers that match or do not match the acoustic impedance depending on their respective attenuation levels, and (2) can significantly attenuate the energy of sound waves.

[0033]

[0067] When performing ultrasound imaging, numerous design considerations can be introduced into the probe design and packaging process. For example, innovative solutions may include, in addition to ergonomic requirements, techniques for housing both acoustic and optical subarrays within a handheld probe of the same size and shape as conventional ultrasound probes; techniques for reinforcing the probe and subarrays to withstand the forces applied to the device during use; and techniques for ensuring that the thermal energy generated by the PIC and PZT modules is efficiently dissipated into the surrounding air without causing discomfort to the patient or operator.

[0034]

[0068] For operating such a mixed array ultrasonic probe, a compact nosepiece 112 is used, characterized by a short overall rise length at the front end and an overall input / output (I / O) area width comparable to the azimuthal width of the sensor array area. The package design of the PIC module 158 adheres to one or more of the following considerations: (1) minimizing the number of I / O channels and I / O pitch; and (2) minimizing the physical size of the assembly by routing fibers and wires so that they bend sharply outside the chip. The embodiments described herein address these design considerations.

[0035]

[0069] Due to the nature of mixed arrays, a geometric gap is created between the two sub-arrays; minimizing this gap benefits both imaging quality and a compact probe elevation footprint. Furthermore, in practical applications, it may be desirable to minimize the nosepiece in the E direction so that the overall probe elevation at the patient interface approaches the elevation of the acoustic aperture. However, it should be noted that photoacoustic sensors (such as chip-based sensors) typically operate with optical and electrical signals in a plane (the EL plane of the probe coordinates). Therefore, sharply refracting both the optical and electrical signals at nearly right angles can prevent the introduction of extra structure into the nosepiece, potentially significantly increasing the nosepiece elevation size and the probe's patient interface. As shown in Figures 1A and 1B, an optical refraction space 108 is required to accommodate the electrical and optical signals of the optical sub-array 154.

[0036]

[0070] In the optical subarray 154, optical and electrical signals propagate within the chip's plane, i.e., the EL plane, as shown in Figure 1B. In some embodiments (e.g., a typical handheld mixed linear and curved array probe), on-chip optical I / O and electrical I / O are located on one coupling edge 116 of the chip, which is substantially lateral. On-chip I / O structures 118, particularly optical couplers, must be substantially perpendicular to the coupling edge to minimize insertion loss. However, electrical and optical cables within the transducer body are typically located within the cable plane 120, which is approximately perpendicular to the EL plane, as shown in Figure 1B. Optical and electrical cables may be housed in this space, indicated as a surrounding boundary 122, which can be defined by the ergonomic requirements of the nosepiece 112 and housing 110 and the acoustic aperture 102. Within the probe 100, the cables are bundled and arranged in the directions shown in Figures 1D and 1E in multiple wiring sections, including reflected, refracted cables and on-chip waveguide wiring. Cable fanouts are sometimes introduced to bridge on-chip I / O and cable bundles along the cable fanout direction without occupying too much elevation space (less than 50% of the elevation size of the imaging aperture). This is known as a "sharp bend." In some embodiments (e.g., a typical handheld mixed array transducer of straight and curved elements), a sharp bend is a substantially right-angle bend with deviations caused by design or manufacturing errors, where the cable plane is substantially perpendicular to the on-chip I / O structure 118 and roughly aligned with the housing boundary defined by the elevation direction and ergonomic design.

[0037]

[0071] The axial size of the probe and the design of the housing 110 (i.e., the rear case portion or proximal housing of the probe 100) are typically defined by ergonomic considerations. Such probes allow for considerable pressure to be applied to the patient's skin while maintaining the imaging technician's agility and keen control. Therefore, the shape, weight, center of gravity, and material selection are all important considerations.

[0038]

[0072] Embodiments of the probe housing can incorporate a variety of features. For example, such embodiments may include a Type III anodized aluminum housing with a combination of organic contours, dimples, textures, and overmolded silicon areas. The housing features a clamshell and nose cone for impact resistance and is high strength and lightweight. Aluminum may be superior to other materials thermally, mechanically, and / or chemically. Especially in current designs, where internal electronics are becoming larger, thinner walls can be used to reduce size compared to conventional plastic parts. Adding tactile ridges can enhance grip. Type III anodizing allows the probe to be electrically insulated, resulting in a very strong and scratch-resistant surface. Type III anodized aluminum provides another layer for electrical insulation.

[0039]

[0073] The embodiment may include some or all of the following components and structures. First, the embodiment may include a mounting block 160 for the AEG subarray 152. The AEG subarray 152 may be, but is not limited to, a PZT (example shown in Figures 1C, 1D, and 1E), a single crystal transducer (SCT), a CMUT, a PMUT, or other known AEG transducer. The mounting block is a lightweight, relatively high-strength thermal conductor (such as aluminum). The mounting block 160 acts as a thermomechanical substrate for the AEG subarray 152, providing mechanical stability. The mounting block may include an integrated thermoelectric cooler and thermistor (or thermocouple) for closed-loop control. Also, in one embodiment, a thermally conductive epoxy may be used to mount the AEG module. The PZT module 156 shown in Figures 1C, 1D, and 1E is electrically connected to the adjustment board 192 via a flexible printed circuit board 188 or a conductive layer 189 to adjust the signal from the PZT module 156 and transmit it via a cable.

[0040]

[0074] As shown in Figure 1D, one embodiment also includes a heatsink 196. The heatsink 196 is preferably positioned distal to the sensor and the patient. The heatsink is preferably made of a lightweight and relatively high-strength thermal conductor (e.g., aluminum). The heatsink provides a relatively large surface area with minimal thermal resistance to the housing (so that energy can be dissipated into the surrounding air). The heatsink may also include a very thin layer of thermal conductive compound at the interface between the housing and the heatsink.

[0041]

[0075] The embodiment may also include a mounting block 162 for the optical subarray 154. The mounting block functions as a thermomechanical substrate for the optical subarray 154, providing mechanical stability where the optical links 194 (e.g., fiber array units (FAUs)) and electrical links 186 (e.g., flex circuits) connect to the PIC module 158. The PIC module 158 may be formed as a unit on a single substrate, or it may be formed on multiple substrates to form individual modules, as shown in modules 154a and 154b in Figure 1D. The AEG and optical subarrays 152 and 154 can share the same mounting block or be mounted on two blocks, as shown in Figure 1D, ensuring a robust mechanical fixation and good thermal conductivity. The mounting block 162 for the optical subarray 154 is also preferably made of a lightweight and relatively strong thermal conductor (e.g., aluminum). The mounting block may include an integrated thermoelectric cooler and thermistor (or thermocouple) for closed-loop temperature control. The mounting block includes a BB-O190b for the PIC and may be cast in a milled pocket. Alternatively, the interposer substrate 148 may be fixed directly to the block to allow connection of the PIC flex circuit. A major challenge when integrating both the AEG module and the PIC module into the same ultrasonic device is routing the optical signals from the PIC to the interposer substrate 148 and then through cables. As shown in Figure 1C, optical and electrical I / O are employed, and exemplary techniques for routing the PIC signals are described in detail below.

[0042]

[0076] One embodiment may also include a heat pipe 198, as shown in Figure 1E. The heat pipe 198 connects the mounting block 162 of the optical subarray 154 to the heat sink 196. Such a heat pipe efficiently transfers thermal energy over relatively long distances in confined spaces where forced air convection is not possible. Some embodiments include at least two heat pipes, which improves mechanical stability. Other embodiments may include additional heat pipes to increase the thermal efficiency of spatially unconstrained probes. The heat pipes may be fixed in precision reamed holes in aluminum parts using thermally conductive epoxy.

[0043]

[0077] The mounting block 162 for the optical subarray 154 can be integrated with the aforementioned AEG subarray 152 by fixing it to the mounting block 160 and finally attaching the interposer substrate 148 to the heat sink 196 at the opposite end. Any mechanical and / or thermal connections can be achieved by using screws and thermally conductive compounds at the interface. Finally, assembly fixtures and fasteners are used to ensure that the two systems are properly aligned before the semi-permanent assembly is completed.

[0044]

[0078] An additional consideration is minimizing the acoustic impedance mismatch between the materials required for both stacks in order to receive an effective signal. In interfaces with large acoustic impedance mismatches, waves may be reflected, scattered, or attenuated in other directions. The greater the impedance difference at the junction of the two materials, the greater the energy breakdown. Considering the materials required for the PIC, such as silicon, common matching layer materials for AEGs may not be suitable. Typically, a matching layer is a single or multilayer structure made of epoxy resin, plastic, or other material that has an acoustic impedance between the two bridging layers, bonded to the front of the AEG element, and can improve the acoustic mismatch between the rigid AEG element and the soft tissue of human skin. Aluminum offers excellent impedance matching from an optical standpoint, in addition to its thermal and mechanical advantages.

[0045]

[0079] In practice, the probe is typically pressed against the surface being imaged. The applied force can be up to 30 pounds, and in some cases, even more. Therefore, in some embodiments, the probe needs to be constructed to withstand such forces.

[0046]

[0080] Furthermore, the PIC sensor may be sensitive to local ambient temperature. Embodiments of the probe may include a separate controller (e.g., a thermo-optic phase shifter) to stabilize the operation of the array. Controlling the overall temperature can (1) increase the robustness of the array operation, (2) help save total control power, and (3) maintain the surface temperature of the acoustic aperture within a specified range optimal for medical applications. Therefore, the thermal management component 199 may also be an internal component associated with the optical sub-array 154.

[0047]

[0081] Various methods can be used to manufacture such probes. For example, in one embodiment, the AEG subarray 152 and optical subarray 154 within the nosepiece 112 are manufactured, packaged, and assembled separately during assembly. Then, both modules are mounted on a thermomechanical substrate, and both the regulating substrate 192 and the interposer substrate 148 are also mounted. The FPCs from the modules within the nosepiece 112 are connected to onboard connectors, and the optical cables are secured in strain relief structures within the probe. The electrical coaxial cables connecting the two substrates and the backend system are either (1) soldered to the regulating substrate 192 and the interposer substrate 148 before the probe is assembled, or (2) soldered to a small termination substrate with inter-substrate connectors, connecting to connectors on the regulating substrate and the interposer substrate. Finally, the cables are bundled or bundled separately and overmolded within a cable tension relief structure (such as a tube).

[0048]

[0082] Figures 2A–2F show examples of compact optical I / O designs and packaging for exemplary probes. As mentioned above with respect to Figures 1B and 1C, size considerations for handheld ultrasound typically mean that the optical I / O, which extends the in-plane (EL plane) optical signal laterally and then refracts it backward toward the axial cable, must be compact in the upward direction. The lossless refraction radius of ordinary optical fibers (especially polarization-maintaining optical fibers) is limited to approximately 5 mm or more. Therefore, compact optical I / O designs based on mirror layers or surface couplers have been proposed, as shown in Figures 2A–2F. The bonding area can stabilize the optical coupling against pressing forces during use, which is a unique design consideration for the optical package in mixed ultrasound imaging probes. As shown in Figures 2A–2F, the optical fiber array is axially aligned approximately along the fan-out direction of the cable and coupled to one or more interposer structures for refracting the optical signal with respect to the optical sub-arrays. The optical fiber array can be axially connected to an interposer chip containing a mirror structure at approximately 45 degrees relative to the upward-lateral plane of the optical subarray, via direct edge coupling, one or more other in-plane interposer chips, or one or more surface couplers coupled to the optical subarray. Note that right-angle refraction is assumed in Figures 2A-F. If the design value of the refraction angle (the angle between the chip I / O direction and the cable fan-out direction in Figure 1B) deviates from 90 degrees, or if multi-stage refraction is required, the refraction angle and the reflection mirror angle can be adjusted to achieve the designed refraction.

[0049]

[0083] Figure 2A shows an example of an optical I / O design based on mirror coating using an interposer chip. As shown in Figure 2A, this design is based on a mirror coating 202 on a 45-degree polished fiber array 204 that achieves right-angle (e.g., approximately 90 degrees) refraction. An interposer chip 210 including a spot size converter is introduced to optimize the coupling between the on-chip optical modes after mirror reflection and the in-fiber optical modes. The spot size converter is optional if the coupler's manufacturing process is compatible with the PIC chip's manufacturing process. An edge coupler 206 is used to couple the interposer chip 210 to the fiber array 204 and the PIC module 220 and BB222. The distance (represented by l) between the coupling edge of the PIC module and the housing of the mixed ultrasound imaging probe reflects how compact the mixed ultrasound imaging probe can be made by various optical I / O designs. The distance can also represent the size in the upward direction of the optical I / O. With the design in Figure 2A, l a It is possible to achieve a thickness of <3mm. Figure 2E shows an example of another optical I / O design based on mirror coating without an interposer chip.

[0050]

[0084] Figure 2B shows an exemplary optical I / O design based on a linear fiber array. As shown in Figure 2B, this design is based on a linear fiber array 204 coupled to a surface coupler 208, enabling right-angle refraction. Compared to Figure 2A, the footprints of the fiber array 204 and the interposer chip 210 overlap, resulting in an increased size l b<2mm can be achieved. Note that the interposer chip 210 enables either an upper surface coupler or a lower surface coupler (e.g., inverting the interposer chip) without using optical coupling via the chip from the fiber array 204. The interposer chip 210 is optional, but the PIC chip typically has an optical structure on top to better / easier acoustic coupling (some of the alternatives described here (e.g., Figure 12) show examples where the optical structure is not on top of the PIC). Another notable advantage of this design is that it is compatible with two-dimensional (2D) arrays of surface couplers (e.g., Figure 5) and can be combined with (1) multi-core fiber (array) or (2) 2D arrays of single-core fiber. In some embodiments, the fiber array is a mixture of single-mode fiber ("SMF") and polarization-maintaining fiber ("PMF").

[0051]

[0085] Figure 2C shows an exemplary optical I / O design based on a vertical interposer chip with a linear fiber array. As shown in Figure 2C, the vertical interposer chip 210 is coupled to the linear fiber array 204 and also to an edge coupler 206 on the PIC chip via a surface coupler 208. In Figure 2C, the surface coupler 208 is assumed to be implemented as a structure within the same optical layer (e.g., silicon, silicon nitride) as the waveguide coupler and edge coupler. Right-angle refraction of the optical path can also be achieved by a 45-degree mirror structure within the vertical interposer chip. In this case, the rise size of the optical I / O becomes the most compact, for example, l c <1mm becomes possible. However, it should be noted that conventional surface couplers, such as grating couplers (GCs), typically operate with radiation angles less than right. The most common angle is 10 degrees from perpendicular radiation (80 degrees of refraction in this state). Furthermore, the radiation pattern of a GC is much larger than that of a waveguide mode. Therefore, special designs of surface couplers are required to enable nearly 90-degree radiation and compact radiation mode sizes in order to achieve a compact footprint and high coupling efficiency.

[0052]

[0086] FIG. 2D is an exemplary optical I / O design based on a vertical interposer chip having a mirror structure. As shown in FIG. 2D, this design is based on a vertical interposer chip having a 45-degree mirror structure with a mirror coating 202 that achieves a right-angle (e.g., about 90 degrees) refraction. A spot size converter (not shown for the sake of option) on the vertical interposer chip 210 can be designed near the mirror structure optimized for coupling between the on-chip optical mode and the waveguide mode of the vertical interposer chip 210. The rising size of the optical I / O is the same as in FIG. 2C and is determined by the thickness of the vertical interposer chip. In this case, l d <1 mm is possible.

[0053]

[0087] FIG. 2E is an example of an optical I / O design based on a mirror coating without an interposer chip. As shown in FIG. 2E, this design is the same as FIG. 2(a) except for the interposer chip 210. In this design, the rising size of the optical I / O is determined by the thickness of the upper fiber array 204. Note that the figure is not to scale and the array definition structure (such as a V-groove) may exist on either side of the PIC module 220. In this method, l e can also be very small, for example, l e <1 mm is possible.

[0054]

[0088] FIG. 2F is an exemplary optical I / O design based on a plurality of interposer chips connected to a fiber array. As shown in FIG. 2F, this design is different from the design of FIG. 2A, but the 45-degree polished fiber array is replaced by a fiber array connecting to a vertical interposer chip having a 45-degree mirror structure (similar to FIG. 2D). The rising size of the optical I / O is determined by the length of the horizontal interposer chip and the thickness of the vertical interposer chip. l f is l aIt is similar to the above. As shown in Figure 2F, the design is based on a vertical interposer chip and a horizontal interposer chip. Note that in coupling the interposer and the PIC chip, it is effective to utilize a focusing structure on the surface coupler to match the mode mismatch between the radiated modes and the modes within the PIC chip.

[0055]

[0089] Figure 3 is another diagram showing Figures 2A and 2E in more detail, according to one embodiment. The mode field 302 in Figure 3 is the core of the fiber array 304. The fiber array 304 includes cladding 314. In the design shown in Figure 2A, a 45-degree mirror coating 306 is introduced to connect the axial optical path in the fiber array 304 with the ascending optical path on the interposer / PIC chip on the substrate 312. However, as shown in Figures 2A and 2E, without further modification of the fiber, the free-space transmission range, i.e., the coupling gap (d) between the axial fiber modes (e.g., fiber array 304) and the ascending waveguide modes (e.g., interposer substrate), can be modified. gap The fiber radius is limited to more than 62.5 μm (40 μm and 25 μm are also available)). Meanwhile, the spot size converter 310 in the interposer substrate is designed to match the mode size difference between the waveguide mode (typically about 1 μm) and the fiber mode (e.g., mode diameter about 10 μm). In free-space transmission, significant mode divergence can occur that can hinder effective mode matching, so efficient coupling uses a minimum coupling gap (1-5 μm). Therefore, compared to a straight fiber array unit (FAU) mounted on an interposer chip, the design is as shown in Figure 2A. gap A large value can lead to increased insertion loss. Note that when packaged, the gap between the fiber array 304 and the interposer / PIC can be filled with an adhesive having a refractive index similar to that of glass, and the curved boundary of the fiber array becomes almost invisible in free-space mode after reflection. Therefore, the boundary will have little to no focusing effect.

[0056]

[0090] Various platforms for optical I / O design can be used in various examples. As shown in Figures 2A-2F, the inherent features and limitations of optical I / O design determine the performance of optical I / O design on different platforms. For example, the FAU platform can be used. Both one-dimensional (1D) fiber arrays and two-dimensional fiber arrays (such as multi-core fibers) are available. Fiber diameters (such as the pitch of a 1D fiber array) of 125 (~127) μm, 80 (~82) μm, and 50 (~52) μm are available. Mirror coating as shown in Figure 2A is feasible (e.g., using a V-groove and cover structure). Polishing to reduce the cladding between the core and interposer / PIC is also possible, but achieving d_gap < 10 μm is difficult due to (1) limitations in polishing accuracy and / or (2) the need for sufficient cladding thickness to maintain low loss.

[0057]

[0091] Another embodiment utilizes a PIC platform, including but not limited to a silicon, silicon nitride integrated photonics platform manufactured using a CMOS-compatible process. Compared to a sensor chip, an interposer chip has simpler optical wiring with couplers and spot size conversion designs for connecting optical modes from different optical waveguides (such as fiber to on-chip waveguides). The suspension and multilayer structure provides flexibility in coupler design and optimization.

[0058]

[0092] In yet another embodiment, a glass-based platform (e.g., a planar lightwave circuit) is used. Planar lightwave circuits (PLCs) are based on glass materials, and microfabrication processes enable them to achieve a thin and compact footprint. While the variety of optical components available on PLC platforms is not as broad as on PIC platforms, optical wiring, spot size converters, densely dispersed couplers, and wavelength division multiplexing (WDM) components are available. Furthermore, compared to PIC platforms (based on single-crystal substrates and multilayer CMOS processes), PLC platforms are lower in cost, have shorter lead times, and offer greater manufacturing flexibility, making them a suitable platform for replacing FAUs and interposer chips (PIC platforms).

[0059]

[0093] Various solutions can be used to minimize the bond gap. For example, as mentioned above, one way to minimize the bond gap in Figure 2A is to polish the fiber cladding. Such a process is likely to achieve a small bond gap of 10-20 μm, as (1) polishing accuracy and (2) cladding thickness that is too thin can result in significant losses to the fiber.

[0060]

[0094] In another embodiment, the root cause of the large coupling gap in design (a) is the thick (e.g., tens of microns) cladding in the optical fiber. To minimize the gap, the fiber-based structure can also be replaced with one or more planar interposers (PIC or PLC), which are angled and polished, and the facets are mirror-coated. This solution can be treated as a variation of the design in Figure 2C, in which the on-chip surface coupler is replaced with an angled mirror and an in-plane coupler.

[0061]

[0095] Figure 4 is another diagram of Figure 2D, showing an example of an interposer having a 45-degree mirror structure according to one embodiment. Note that a horizontal interposer can be added between the vertical interposer 402 and the PIC module, as shown in Figure 2F. The horizontal interposer may include a spot size converter 404. In Figure 4, the horizontal dashed line 406 represents the mirror image of the waveguide within the horizontal interposer. As shown in Figure 4, the vertical interposer 402 is mechanically polished to 45 degrees and then coated with a mirror. The vertical interposer 402 can be implemented in both CMOS-compatible PIC and PLC platforms. A glass PLC platform is used as an example because it is advantageous in terms of cost and lead time, and any polishing of the glass substrate is widely available. In other examples, a PIC platform can be used, and silicon or silicon nitride can be polished to 45 degrees. During the deposition of the mirror coating, the transparent facets may be protected by (1) a directional deposition process, (2) a removable protective layer against deposition from all directions (e.g., a photoresist layer), or (3) allowing exposure to deposition from all directions but subsequently polishing. Gap size d gap The thickness of the glass cover that defines the mirror coating is selected to (1) minimize the impact on coupling efficiency and (2) improve the yield of the mirror coating in front of the spot size transducer 404 (the mirror coating in the gap area acts as a protective layer or a buffer zone for post-polishing).

[0062]

[0096] The probe embodiment must consider high laser power design, and therefore, increasing coupling efficiency may be beneficial. To achieve high efficiency and approach uniformity, a focusing coupler can be used. This is because most couplers on the chip form a divergent radiation wavefront, while uniform coupling is a time reversal of radiation, i.e., a focused wavefront. Therefore, optical fixtures with right-angle refraction and a focused wavefront based on microfabrication and micromanufacturing, rather than nanofabrication of the PIC, can be utilized. Note that the following designs can be implemented on a fiber FAU platform, PLC platform, or PIC platform.

[0063]

[0097] Figure 5 is another diagram of Figure 2B showing a 2D surface coupler array and multicore fibers in a fiber array according to one embodiment. As shown in Figure 5, there are seven surface couplers 502 forming the 2D surface coupler array. The 2D surface coupler array is coupled to an interposer chip 504 and a fiber array. The fiber array in Figure 5 includes one or more multicore fibers 506.

[0064]

[0098] Figure 6A is a diagram of an embodiment of a reflective focusing right-angle optical fixture according to one embodiment. Figure 6B is an example of the manufacturing process of the reflective focusing right-angle optical fixture of Figure 6A according to one embodiment. As shown in Figure 6A, a convex microstructure 602 can be fabricated on an angled surface 604, and a focusing mirror can be formed after mirror coating. The spot size converter 608, waveguide 610, and substrate can be the same as those in Figure 3. As shown in Figure 6B, the manufacturing process begins with an optical waveguide array 616, for example, as shown in step (I) of the FAU interposer. As shown in step (II), a 45-degree facet 618 is formed by angle polishing. Next, as shown in step (III), the convex microstructure 602 is aligned with the 45-degree facet 618 by, for example, two-photon 3D printing, nanoimprint, polymer reflow, etc. As shown in step (IV), a mirror layer 620 (e.g., a gold layer, a dielectric multilayer, etc.) is deposited on the entire fixture, followed by optical polishing of the transparent facets as shown in step (V) (optional if the mirror coating is directional). The focal length of the microfocus mirror is achieved by controlling the thickness of the cover. Apart from the focusing made possible by the reflective convex structure, this design minimizes the interface or coupling line between the reflective surface and the on-chip spot size converter, which can help minimize interface reflections. However, since the curved reflective surface refracts the light field and focuses in a single reflection, the shape of the convex surface must be carefully designed and controlled during the manufacturing process.

[0065]

[0099] Figure 7 shows a right-angle refractive and focusing optical fixture with a lens plate according to one embodiment. While refractive lens structures combined with FAUs are known, existing designs do not provide a flat bonding surface, limiting their applications to in-line testing rather than optical packaging. The lens is made of a high refractive index material to concentrate light to a low refractive index. In Figure 7, a flat surface is used for bonding in the packaging between the off-chip waveguide (such as a FAU) and the on-chip waveguide. The lens may be positioned before or after the 90-degree refraction.

[0066]

[0100] Figure 7 shows the design of a refractive focus right-angle optical fixed lens plate 702 positioned after 90-degree refraction. As shown in Figures 4 and 6A, for example, the left half of the fixture is a fiber array structure 704 including the waveguide 706 described above. The right half, i.e., the lens plate 702, can be manufactured separately. The lens 708 is positioned at a lens-front distance 710 and a depth of focus 712, directing the light to the spot size converter 714 and the on-chip waveguide 716 located on the substrate 718. Note that additional low refractive index coatings may be used to modify the microlens array plate to meet design specifications. Compared to reflective focus, the manufacturing yield of the refractive focus is higher. Furthermore, because the lens is aligned to the divergent beam, the alignment tolerance is also larger than that of the reflective focus method.

[0067]

[0101] Figure 8 shows a design based on photonic wire bonding technology in a probe according to another embodiment. The polymer waveguide (e.g., photonic wire) that provides mode-field matching with both the optical fiber 802 and edge coupler 806 on the PIC chip can be fabricated directly by nanoscale 3D printing. To enhance the stability of the optical coupling, a glob top or protective layer can be added. In this design, the rise size of the optical I / O is, in principle, approximately the same as the diameter of the fiber. However, this may be affected by the potential limitations imposed by the minimum refractive radius of the photonic wire bonding 804, which can be minimized by the waveguide design and the contrast of the refractive index of the material.

[0068]

[0102] Figures 9A–9F show examples of compact electrical I / O designs and packaging for exemplary probes. Electrical design considerations for I / O are similar to those for optical I / O; however, electrical contacts may be surface pads on the PIC chip. Therefore, electrical contacts can be interleaved to form a 2D array, reducing the effective pitch of the electrical I / O ports. Electrical connections between optical subarrays and flexible printed circuits can be achieved using an interposer chip or substrate. Various electrical I / O designs are summarized in Figures 9A–9F.

[0069]

[0103] Figure 9A shows an example of an electrical I / O design including a 1D pad array for wire bonding a PIC chip and an FPC. As shown in Figure 9A, electrical contacts 902 on the PIC chip 904 (supported by a backing block 912) are wire-bonded to pads 906 on the PCB substrate 908 (such as an FR-4 printed circuit board (PCB), aluminum nitride (AlN) substrate), and connected via one or more vias (not shown) to solder pads on the back of the PCB substrate. The FPC 910 is bonded to the back side, which allows for a wider solder pad pitch (see Figure 1C) because (1) the solder area is wider, (2) it can be refracted within the PCB substrate 908, and (3) the FPC 910 can overlap with the optical I / O in the EL plane. Note that the height size la of this design is determined by the footprint of the vias on the PCB substrate 908.

[0070]

[0104] Figure 9B is an example of another electrical I / O design that includes a 1D pad array for wire bonding the PIC chip and FPC. As shown in Figure 8B, the electrical contacts 902 on the PIC chip 904 are wire-bonded to bonding pads 914 on the FPC 910, which is supported by a reinforcing material 916 (or the thermomechanical substrate itself). Compared to Figure 9A, this design uses a high-resolution FPC to match the electrical I / O pitch on the PIC chip 904 and has a smaller height size without using vias.b This can be achieved.

[0071]

[0105] Figure 9C is an example of yet another electrical I / O design including a 1D pad array for wire bonding the PIC chip and FPC. As shown in Figure 9C, the electrical contacts 902 on the PIC chip 904 are wire-bonded to a cross section 918 of a thick FPC bonded to the side of the backing block 912. An ultra-compact raised footprint of lc < 1 mm is achievable. Note that the reinforcement 920 may be optional or temporary. The reinforcement 920 serves as a hard support for alignment with the electrical contacts 902 on the PIC chip 904. In some embodiments, it may be removed after the electrical link has been protected (e.g., with a glob top).

[0072]

[0106] In the examples shown in Figures 9D-9F, a flip-chip bonding process is used instead of a wire bonding process, supporting a 2D pad array. For simplicity, only two rows of pads are shown in the figures.

[0073]

[0107] Figure 9D is an example of an electrical I / O design including a 2D pad array for joining a PIC chip and an FPC by flip-chip bonding. As shown in Figure 9D, bonding pad 922 on the FPC 910 is flip-chip bonded to pad 924 on the PIC chip 904 via solder bumps or anisotropic conductive paste (ACP). Reinforcement 926 is optional or temporary. After bonding, reinforcement 926 can be removed. If left permanently, reinforcement 926 can function as (1) a hard protector providing superior robustness to the joint, (2) an electrical insulator, or (3) a flat base structure for further vertical integration.

[0074]

[0108] Figure 9E shows another example of an electrical I / O design that includes a 2D pad array for bonding a PIC chip to an FPC via flip-chip bonding. As shown in the example in Figure 9E, the electrical contacts 928 on the PIC chip 904 are instead located on the back surface and connected to metal traces 930 near the top surface by through-silicon vias (TSVs) 932. During assembly, the PIC chip 904 is first bonded to the FPC 910 (via solder bumps or ACP, etc.) and then bonded to the backing block 912 using minimal bonding lines below the sensor area. If necessary, the gap between the reinforcement 934 and the backing block 912 can also be filled with underfill material or adhesive.

[0075]

[0109] Figure 9F shows another example of an electrical I / O design that includes a 2D pad array for bonding a PIC chip and an FPC via flip-chip bonding. As shown in the example in Figure 9F, both the electrical contact 936 on the PIC chip 904 and the FPC cross section 918 are flip chips bonded to the bridge interposer 938. The reinforcement 940 is optional or temporary.

[0076]

[0110] The rise size of the three designs in Figures 9D to 9F is determined by the refractive radius and FPC thickness, respectively, and can all be kept to less than 1 mm. In some cases, the rise size l of the electrical I / O design above the top surface of the PIC chip (e.g., l in Figures 9A to 9F) a ,l b ,l c ,l d ,l e , and l f The size l of the optical I / O design (for example, l in Figures 2A-2F) can be limited to 0.5 mm or less for wire bonding and 0.2 mm or less for flip-chip designs. a ,l b ,l c ,l d ,l e , and l f This can be limited to within 0.2 mm from the top edge of the PIC chip.

[0077]

[0111] In one embodiment, the probe is manufactured as follows: First, the substrate is mounted directly to the flex cable using solder reflow or ultrasonic thermocompression bonding, and underfill may be included if necessary. Next, the die facets are polished depending on whether the die is a right die ("RHD") or a left die ("LHD"). Next, the die is subdivided according to the configuration. Next, one or two dies are mounted to each submount / flex assembly. One or two flake thermistors are also mounted to each submount / flex assembly. Next, the dies are wire-bonded to the AlN submount using glob tops. Next, the Peltier cooler is mounted to the underside of the AlN submount and the leads are soldered to the AlN submount. Finally, the fiber array is mounted to the assembly using appropriate fasteners.

[0078]

[0112] Figure 10A shows a design of AEG module 10000a according to one embodiment. Figure 10B shows a conventional design of AEG module 1000b according to one embodiment. In Figure 10A, AEG module 1000a is a PZT subarray with transducer element 1002a, electrical connector (e.g., wire) 1004a, and notch 1006a between transducer elements 1002a. In Figure 10b, AEG module 1000b is a PZT subarray with transducer element 1002b, electrical connector (e.g., wire) 1004b, and notch 1006b between transducer elements 1002b. The structure has been significantly altered compared to conventional ultrasound imaging probes, and this new probe tends to minimize the spacing between the two subarrays, resulting in significant differences in design considerations and manufacturing processes for PZT subarrays.

[0079]

[0113] To minimize the gap between the PIC subarray and the AEG subarray, sharp, clear edges are desirable. However, in conventional ultrasonic array manufacturing methods, the acoustic stack and circuitry extend uniformly along the upward direction, as shown in Figure 10B. In the illustrated array design, to achieve an AEG array where the circuitry extends along only one side, as shown in Figure 10A, the size of the transducer array can be doubled in the upward direction, and a new process called "double dicing" can be employed, as shown in Figure 11.

[0080]

[0114] Figure 10C shows the manufacturing of an AEG module 1000c according to one embodiment. Figure 10D shows a conventional manufacturing method of an AEG module 1000d according to one embodiment. As shown in Figure 10C, the transducer array region 1008a within the circuit board 1010a is enlarged by a factor of two, and the electrical connector 1004a traverses the entire circuit board. In contrast, in the conventional design of Figure 10D, the electrical connector 104b alternately switches between connecting to and from the transducer array region 1008b. The electrical connector 104a traversing the entire circuit board 1010a allows access to the elements from both ends of the circuit. The difference in size and connection method is preparation for a "double dicing" process to achieve clean, sharp edges of the subarray. Therefore, before dicing, the piezoelectric material is placed between the backing block and one or more matching layers.

[0081]

[0115] Figure 11 shows a double dicing process according to one embodiment. A cross-section of an array, such as the AEG module 1000a shown in Figure 10a, is shown during the “double dicing” process in Figure 11. To achieve edge design considerations, a high-precision and high-accuracy dicing saw is implemented to dice and separate the acoustic stack (matching layer 1102 and piezoelectric material 1104), with the resulting saw cut slightly extending to the backing block 1106. The dicing saw can leave an ultrafine cut surface, but the depth of the cut is still limited by the blade clearance (e.g., cut 1006a). The backing block 1106 is a critical component of the ultrasonic array, and its thickness can typically be several millimeters, which prevents the entire array from being split into two in a single cut. Therefore, this process implements a computer numerical control (CNC) machine to cut the backing block from below. These two cuts can be aligned with a fixture.

[0082]

[0116] Once the "double dicing" process is complete, two symmetric ultrasonic arrays of Array 1000a, as shown in Figure 10A, can be obtained. A special circuit design allows access to both arrays with the same pin map, and "double dicing" ensures that the edges of both arrays, as realized by the dicing saw, are clean and sharp.

[0083]

[0117] Figures 12-14 show various configuration examples of I / O packaging designs, including thermomechanical substrates and housings for probes, in several embodiments. Figure 12 shows an alternative design for a PIC module package according to one embodiment. In Figure 12, the PIC chip 1202 is flip-chip bonded to the FPC 1204 via electrical contacts 1212. In Figure 12, the optical layer 1206 (optical coupler, waveguide, sensor, etc.) is considered to be close to the top layer of the PIC chip 1202. Figure 12 also shows an additional design for optical I / O. Right-angle refraction of optical signals can be achieved by directly attaching a fiber array 1208, which is 0-10 degrees from the vertical angle, to the surface coupler 1210. The fiber array 1208 can also be bonded to the backing block 1214 via a bonding region 1216.

[0084]

[0118] Figure 13 shows a design of a conical nosepiece according to one embodiment. In some embodiments, the rise size of the nosepiece is smaller than that of the design described above. Therefore, a conical nosepiece 1302 can be introduced as shown in Figure 13. In Figure 13, a thick acoustic front stack 1304 lifts the acoustic aperture (not shown) so that the extra footprint of the I / O structure (both on-chip and off-chip) can be accommodated in the wider base of the nosepiece, while simultaneously achieving a narrow top interface. Other components shown in Figure 13 are generally as described in Figure 1C.

[0085]

[0119] Figure 14 shows an alternative design for a mixed ultrasonic imaging probe according to one embodiment. In some embodiments where the rise size of the acoustic aperture (not shown) is too restrictive to accommodate the PZT module and PIC module when placed side by side, the alternative design shown in Figure 14 can be introduced. In the electrical I / O designs shown in Figures 9D and 9E, and the alternative design shown in Figure 9A, a flat top surface can be provided in the non-sensing area of ​​the PIC module 1402 to which the PZT module 1404 can be bonded. The PIC module 1402 is supported by a backing block (e.g., BB-1) 1410. The PIC module 1402 is coupled to an optical link 1432 and an electrical link 1430. Figure 14 assumes an electrical I / O design based on the example shown in Figure 9E. Note that the reinforcing material 1406 and BB-21408 can be shared in a single component, such as being made of the same material. In the examples shown in Figures 9A and 9E, the reinforcing material and FPC are located beneath the PIC. In Figure 14, the reinforcing material 1406 and FPC 1416 are located on top of the PIC module 1402. An acoustic window 1414 can be placed between the acoustic front stack 1412 and the PIC module 1402. A matching layer ML-O21418 may be present between the acoustic window 1414 and the PIC module 1402. A matching layer ML-O21420 may be present between the acoustic front stack 1412 and the acoustic window 1414. A matching layer ML-P 1422 can be placed between the PZT module 1404 and the acoustic front stack 1412. A conductor layer 1424 may be present between the matching layer ML-P 1422 and the PZT module 1404. The PZT module 1404 can be connected to the electrical link 1428 via a flexible layer 1426.

[0086]

[0120] As with various other drawings, the sizes of the elements shown in Figure 14 do not represent the actual sizes of each component within a particular probe. In some embodiments, the axial offset between the PIC sensor and the PZT ultrasonic transducer is addressed by implementing a dematching layer within the structure. This dematching layer may be assembled between the PZT module 1404 and the flex layer 1426 in Figure 14, or between the flex layer 1426 and the BB-2 1408. The dematching layer can significantly reduce the thickness of the BB-2 1408.

[0087]

[0121] The exemplary probes described herein may offer one or more advantages. For example, some probe examples integrate a PZT ultrasound transmitting and receiving system with a PIC ultrasound receiving system to achieve and maintain proper relative positioning of the two systems. Such examples provide further mechanical stability to both sensors (in combination with the housing) under normal operating conditions. Furthermore, such examples can efficiently transfer thermal energy from the PZT and PIC sensor arrays, mitigating or minimizing thermal performance degradation (e.g., no software "throttling" is used). Such examples also reduce or minimize the amount of heat transmitted to the patient and the technician.

[0088]

[0122] Furthermore, the exemplary probe may help reduce manufacturing costs by, for example, utilizing the principle of "design for manufacturing" in the CNC milling of aluminum parts. Additionally, the exemplary probe can be assembled relatively easily, for example, because fixtures are used for proper sensor alignment. The sample probe may also help reduce or minimize the number of parts used in constructing the probe. Moreover, the mixed array subassembly (excluding the housing and acoustic lens) can be securely mounted on a flat surface without additional mechanical support. Such a modular design allows for the separate evaluation of the mechanical assemblies of both individual systems before integration, facilitating disassembly for maintenance and diagnostics.

[0089]

[0123] In some embodiments, a curved acoustic front facet, commonly known as a curved transducer, is required. Since most PIC platforms have a solid substrate, a modularized optical subarray (such as modules 154a and 154b) can be introduced to realize the curved facet. Figure 15A is a schematic diagram of a stepped modularized optical subarray with individual backing blocks according to one embodiment. Figure 15B is a schematic diagram of a stepped modularized optical subarray sharing an integrated backing block embedded in a thermomechanical substrate according to one embodiment. Figure 15C is a schematic diagram of a modularized optical subarray arranged in a polygonal pattern with individual backing blocks according to one embodiment.

[0090]

[0124] As shown in Figures 15A-15C, eight optical subarrays (e.g., 1504-1, 1504-2, ..., 1504-8) are assembled on a single thermomechanical substrate to form a non-planar acoustic receiving window defined by ML-O. However, the number of modularized optical subarrays is not limited to eight. The non-planar acoustic receiving window is a special case of the optical subarray shown in Figure 1C. Acoustic receiving windows 1500A and 1500B in Figure 15A are both stepped. In contrast, acoustic receiving window 1500C in Figure 15C is polygonal.

[0091]

[0125] In Figures 15A to 15C, curved acoustic interfaces (e.g., interface 1502a in Figure 15A, interface 1502b in Figure 15B, and interface 1502c in Figure 15C) cover the acoustic receiving window. The curved acoustic interface can be shared between the piezoelectric subarray and the optical subarray, or it can be independent of the piezoelectric subarray interface.

[0092]

[0126] An acoustic interface may include multiple elements. For example, interface 1502a in Figure 15A and interface 1502b in Figure 15B may include an acoustic window made of a low-acoustic-attenuation material to compensate for the uneven thickness of the interface, and a uniform, thin lens material on top. In Figure 15A, each modularized optical subarray includes a separate BB-O. In Figure 15B, each subarray uses a PIC as a substrate and shares an integrated BB embedded in a thermomechanical substrate.

[0093]

[0127] Similar to Figure 15B, an integrated barbed layer (BB) is designed for the polygonal acoustic receiving window shown in Figure 15C. Generally, the BB layer requires a thickness of several centimeters, which can result in large gaps between adjacent acoustic receiving windows.

[0094]

[0128] The above-described examples of embodiments are presented for illustrative and explanatory purposes only and are not intended to be exhaustive or to limit the disclosure to the exact form disclosed. Numerous modifications and adaptations will be apparent to those skilled in the art without departing from the spirit and scope of the invention.

[0095]

[0129] References to embodiments, examples, or implementations in this specification mean that certain features, structures, operations, or other characteristics described in relation to an example may be included in at least one implementation of this disclosure. This disclosure is not limited to any specific example or implementation described herein. Whenever the words “in one embodiment,” “in one example,” “in one example,” “in one implementation,” or “in an implementation” appear in different parts of this specification, they do not necessarily refer to the same example or implementation. Certain features, structures, operations, or other characteristics described in relation to one example or implementation in this specification may be combined with other features, structures, operations, or other characteristics described in relation to other examples or implementations.

[0096]

[0130] The use of the word "or" in this specification is intended to cover both inclusive and exclusive OR conditions. That is, A or B or C, depending on the specific use, may include any or all of the following alternative combinations: A only; B only; C only; A and B only; A and C only; B and C only; and A, B, and C.

Claims

1. A device used to image an object, Housing and The distal portion coupled to the housing, A first acoustic subarray on a substrate configured to transmit an acoustic signal toward the aforementioned object, A second optical subarray on a substrate configured to detect the acoustic signal from the object, An input / output (I / O) region comprising one or more optical I / O channels configured to refract optical signals between the optical subarray and one or more optical I / O channels, wherein the one or more optical I / O channels comprises an optical fiber array in the axial direction, comprising an input / output (I / O) region, and a distal portion thereof, A device equipped with the following features.

2. The apparatus according to claim 1, wherein the acoustic subarray comprises an acoustic energy generation (AEG) transducer, and the AEG transducer comprises one or more of the following: a piezoelectric transducer, a lead zirconate titanate (PZT) transducer, a polymer thick film (PTF) transducer, a polyvinylidene fluoride (PVDF) transducer, a capacitive micromachine ultrasonic transducer (CMUT), a piezoelectric micromachine ultrasonic transducer (PMUT), a photoacoustic transducer, and a single crystal transducer.

3. The apparatus according to claim 1, wherein the optical subarray comprises one or more photon integrated circuit (PIC) modules including interference-based optical sensors, optical resonators, or interferometers.

4. The apparatus according to claim 1, wherein the first substrate comprises aluminum, and the acoustic subarray is attached to the first substrate via thermally conductive epoxy.

5. The apparatus according to claim 1, wherein the first substrate is equipped with an integrated thermoelectric cooler.

6. The apparatus according to claim 1, wherein the first substrate comprises a thermistor or a thermocouple.

7. The apparatus according to claim 1, wherein the second substrate is made of aluminum.

8. The apparatus according to claim 1, wherein the second substrate comprises a backing block for the optical subarray.

9. The apparatus according to claim 1, wherein the housing further comprises a tuning circuit electrically connected to the acoustic subarray, the tuning circuit being configured to adjust the acoustic signals transmitted from the acoustic subarray.

10. The apparatus according to claim 1, wherein the optical fiber array comprises an angled surface having a mirror coating for refracting optical signals to and from the optical subarray.

11. The apparatus according to claim 10, wherein the angled surface is at approximately 45 degrees with respect to the rise-to-lateral plane of the optical subarray.

12. The apparatus according to claim 10, wherein the angled surface further comprises a reflection focus right-angle optical fixture.

13. The apparatus according to claim 1, wherein the one or more optical I / O channels further comprises a refractive focusing right-angle optical fixture including a lens plate, the lens plate being bonded to the optical fiber array and / or interposer chip via a plane.

14. The apparatus according to claim 1, wherein the one or more optical I / O channels further comprises polymer waveguides connecting the optical fiber array and the optical subarray via one or more edge couplers on the optical subarray.

15. The apparatus according to claim 1, wherein the optical fiber array is coupled to an interposer chip that is connected in the upward direction to the optical subarray via one or more surface couplers.

16. The apparatus according to claim 1, wherein the optical fiber array is connected in the axial direction to an interposer chip having a mirror structure at approximately 45 degrees with respect to the upward-lateral plane of the optical subarray.

17. The apparatus according to claim 1, wherein the I / O region further comprises one or more electrical I / O channels, and the one or more electrical I / O channels comprises a flexible printed circuit.

18. The apparatus according to claim 17, wherein the distal portion further comprises an interposer substrate electrically connected to the optical subarray via one or more electrical I / O channels, and the interposer substrate is configured to optimize the coupling between the optical subarray and the one or more optical I / O channels.

19. The apparatus according to claim 17, wherein the flexible printed circuit is connected to the optical subarray via one-dimensional pad array wire bonding.

20. The apparatus according to claim 17, wherein the flexible printed circuit is connected to the optical subarray via two-dimensional pad array flip-chip bonding.

21. The apparatus according to claim 17, wherein the optical subarray is wire-bonded to a first surface of a PCB substrate, and the flexible printed circuit is wire-bonded to a second surface of the PCB substrate.

22. The apparatus according to claim 17, wherein the flexible printed circuit is supported by a reinforcing material.

23. The apparatus according to claim 22, wherein the reinforcing material is temporary.

24. The apparatus according to claim 1, further comprising an acoustic front stack, the acoustic front stack comprising an interface layer configured to contact the surface of the object for imaging and to transmit acoustic signals between the apparatus and the object.

25. The apparatus according to claim 24, wherein the acoustic front stack comprises a curved acoustic front facet.

26. The apparatus according to claim 24, wherein the interface layer comprises a biocompatible material having the lowest acoustic impedance.

27. The apparatus according to claim 24, wherein the interface layer comprises an acoustic matching layer having an acoustic impedance that matches the object for imaging.

28. The apparatus according to claim 24, wherein the interface layer comprises one or more acoustic lenses configured to focus and guide the acoustic signal to the object.

29. The apparatus according to claim 24, wherein the interface layer comprises an acoustic window containing a material that reduces acoustic attenuation and matches acoustic impedance.

30. The apparatus according to claim 24, wherein the interface layer comprises a couplant containing an elastomer with low attenuation and impedance.

31. The apparatus according to claim 24, further comprising a first matching layer connecting the interface layer to the acoustic subarray, and a second matching layer connecting the interface layer to the optical subarray.

32. The apparatus according to claim 1, wherein the housing comprises a type III anodized aluminum housing having a combination of organic contours, dimples, textures, and overmolded silicon regions.

33. The apparatus according to claim 1, further comprising a heat sink disposed within the housing, wherein the heat sink comprises a layer of thermally conductive compound that interfaces with the housing.

34. The apparatus according to claim 33, further comprising one or more heat pipes connecting the second substrate and the heat sink.

35. The apparatus according to claim 1, wherein the one or more optical I / O channels are realized on a fiber array unit (FAU) platform.

36. The apparatus according to claim 1, wherein the one or more optical I / O channels are implemented on a PIC platform.

37. The apparatus according to claim 1, wherein the one or more optical I / O channels are implemented on a planar light wave circuit (PLC) platform.

38. The apparatus according to claim 1, wherein the optical subarray is a flip chip, and the optical fiber array is attached to the optical subarray via one or more surface couplers.

39. The apparatus according to claim 1, wherein the distal portion is cone-shaped.

40. The apparatus according to claim 1, wherein the acoustic subarray and the optical subarray are arranged side by side in the upward direction at the distal portion.

41. The apparatus according to claim 1, wherein the acoustic subarray is arranged on a flat upper surface on the non-detection region of the optical subarray in the axial direction.

42. The apparatus according to claim 1, wherein the optical subarray comprises a plurality of modularized optical subarrays arranged in a stepwise manner in the upward direction.

43. The apparatus according to claim 1, wherein the optical subarray comprises a plurality of modularized optical subarrays arranged in a polygonal pattern in the upward direction.

44. The apparatus according to claim 1, wherein the I / O region is less than 3 mm in the upward direction.

45. The apparatus according to claim 1, wherein the I / O region is less than 2 mm in the upward direction.

46. The apparatus according to claim 1, wherein the I / O region is less than 1 mm in the upward direction.

47. The apparatus according to claim 1, wherein the coupling gap in the upward direction between the core of the optical fiber array and the waveguide mode of the interposer is less than 10 μm.

48. A device used to image an object, A first acoustic subarray on a substrate configured to transmit an acoustic signal toward the aforementioned object, A second optical subarray on a substrate configured to detect the acoustic signal from the object, An input / output (I / O) region comprising one or more optical I / O channels configured to refract optical signals between the optical subarray and one or more optical I / O channels, wherein the one or more optical I / O channels comprises an optical fiber array in the axial direction, A device equipped with the necessary components for imaging an object.

49. A method for preparing a mixed ultrasound imaging probe, To provide housing, To provide an acoustic subarray, To provide an optical subarray, Mounting the aforementioned acoustic subarray on a first substrate, Mounting the optical subarray on a second substrate, The optical subarray is connected to one or more optical I / O channels, wherein the one or more optical I / O channels are configured to refract optical signals between the optical subarray and the one or more optical I / O channels, and the one or more optical I / O channels include an optical fiber array in the axial direction. To obtain a mixed array imaging probe, the acoustic subarray is housed on the first substrate, the optical subarray is housed on the second substrate, and one or more optical I / O channels are housed in the housing. A method for preparing a mixed ultrasound imaging probe, including [a specific component].

50. To provide an acoustic front stack, Connecting the acoustic front stack to the acoustic subarray via a first matching layer, Connecting the acoustic front stack to the optical subarray via a second matching layer, The method according to claim 49, further comprising:

51. Connecting the second substrate to the heat sink via one or more heat pipes, A layer of thermally conductive compound is provided between the heat sink and the housing, The method according to claim 49, further comprising:

52. The method according to claim 49, further comprising electrically connecting the acoustic subarray to a tuning circuit, wherein the tuning circuit is housed within the housing.

53. The method according to claim 49, further comprising electrically connecting the optical subarray to an interposer substrate via a flexible printed circuit, wherein the interposer substrate and the flexible printed circuit are housed within the housing.

54. The method according to claim 53, further comprising wire bonding the optical subarray to the flexible printed circuit via a one-dimensional pad array.

55. The method according to claim 54, further comprising wire bonding the optical subarray to the flexible printed circuit via a two-dimensional pad array.

56. The method according to claim 49, wherein the optical fiber array is polished to have an angled surface, and the angled surface is provided with a mirror coating for refracting optical signals from the optical subarray.

57. The method according to claim 56, wherein the angled surface is at approximately 45 degrees with respect to the ascending-transverse plane of the optical subarray.

58. The method according to claim 56, wherein the angled surface further comprises a reflection focus right-angle optical fixture.

59. The method according to claim 49, wherein the one or more optical I / O channels further comprises a refractive focusing right-angle optical fixture including a lens plate, the lens plate being joined to the optical fiber array via a plane.

60. The method according to claim 49, further comprising joining the optical fiber array to the optical subarray via one or more edge couplers on the optical subarray using polymer waveguides.

61. The method according to claim 49, further comprising coupling the optical fiber array with an interposer chip that connects the optical subarray in the upward direction via one or more surface couplers.

62. The method according to claim 49, further comprising connecting the optical fiber array to an interposer chip in the axial direction, wherein the interposer chip comprises a mirror structure at approximately 45 degrees with respect to the upward-lateral plane of the optical subarray.

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