Fiber optic sensor array for sensing and imaging

Abstract

Hybrid sensor array devices are provided herein. Hybrid sensor arrays described herein include acoustic energy generating elements and optical fiber based acoustic sensors. The fiber-based sensor may be an optical structure responsive to physical parameters including acoustic signals, pressure, and temperature, and configured to detect and receive acoustic signals and other physical parameters, and provide associated optical signals to the system for processing and interpretation to implement tracking, positioning, imaging, and other sensing capabilities. Optical fiber-based sensors provided herein may be disposed at the end of an optical fiber or along the length of the optical fiber. The fiber-based sensors may be included within various devices, including, for example, medical devices.

Description

[0001] Related applications

[0002] This application claims U.S. Provisional Application No. 63 / 510,079, filed June 23, 2023, entitled "Fiber-Optical Sensor System for Ultrasonic Sensing and Imaging"; U.S. Provisional Application No. 63 / 522,793, filed June 23, 2023, entitled "Optical Fiber with an Acoustically Sensitive Fiber Bragg Grating and Ultrasonic Sensor Including the Same"; and U.S. Provisional Application No. 63 / 522,793, filed June 23, 2023, entitled "Transponder Tracking and Ultrasonic Image Enhancement". This application is further related to U.S. Provisional Application No. 63 / 522,994, filed June 23, 2023, entitled “Miniature Mixed Array Imaging Probe,” and U.S. Provisional Application No. 63 / 545,327, filed October 23, 2023, each of which is incorporated herein by reference. This application is also related to U.S. Patent Application No. 18 / 382,984, filed October 23, 2023, entitled “Transponder Tracking and Ultrasound Image Enhancement,” which is incorporated herein by reference. Technical Field

[0003] This invention generally relates to the fields of ultrasonic sensing, imaging, and optical sensing. Background Technology

[0004] Acoustic imaging is used in a variety of industries, including medical imaging. Acoustic imaging technology can be used to visualize and provide internal images of a patient's body. Furthermore, it can be used to visualize and track objects (e.g., needles, catheters, guidewires, endoscopes, etc.) for medical applications such as diagnostic or therapeutic clinical procedures, including but not limited to biopsies, fluid aspiration, delivery of therapeutic agents such as drugs, nerve blocks / anesthesia, or biologics, catheter insertion, needle guidance, needle placement, central venous catheterization, injections, IV / PIC line placement, device implantation, minimally invasive surgery, etc. Using acoustic imaging in medical applications offers several advantages. For example, acoustic imaging, such as ultrasound imaging, is a non-invasive form of imaging. Additionally, ultrasound imaging uses ultrasound signals known to have significant penetration depth.

[0005] In non-medical applications, ultrasound is used in industrial applications such as defect detection, non-destructive testing, structural testing, and particle sorting, as well as in geological applications including mining and drilling operations and underwater and marine applications.

[0006] Some existing imaging techniques utilize acoustic energy generation (AEG) materials in transducers to visualize and track medical objects and generate images during diagnostic or therapeutic medical procedures. Commonly used AEG materials include piezoelectric materials such as lead zirconate titanate (PZT), ceramics, piezoelectric single crystals (e.g., PIN-PT, PIN-PMN-PT), and polyvinylidene fluoride (PVDF), as well as many other materials known to those skilled in the art. AEG transducers have limitations. The echoes of the object being tracked and / or the anatomical structures being visualized can affect the image quality of both the tracked object and the tissue being imaged. In some medical procedures, small shape factors are required, and small AEG transducers typically have low to minimal signal output. Therefore, using AEG transducers in medical applications requiring small shape factors can be challenging due to size limitations (e.g., physical dimensions).

[0007] Therefore, especially in medical applications, there is a need for new and improved compact technologies with high sensitivity to visualize and track objects, provide anatomical imaging, and provide measurements of other physical parameters. Summary of the Invention

[0008] This paper presents systems, devices, and methods for ultrasonic sensing, imaging, and multidimensional sensing of physical parameters. Specifically, the systems, devices, and methods described herein may include fiber optic microsensor devices and systems, and methods of using them.

[0009] In some aspects, the technology described herein relates to a device comprising: a housing; a substrate mounted within the housing; a plurality of sensor optical fibers fixed to the substrate, each sensor optical fiber comprising: an optical waveguide; an optical sensor structure configured to: detect an acoustic signal and provide an optical signal corresponding to the acoustic signal to the optical waveguide; and a plurality of acoustic energy generating transducers configured to generate acoustic energy.

[0010] In some aspects, the technology described herein relates to a system for generating ultrasound images, comprising: a light source configured to generate an initial optical signal; a first optical waveguide configured to direct the initial optical signal from the light source to a fiber optic acoustic sensor array configured to detect an acoustic signal; an optical receiving device configured to receive a returned optical signal from the fiber optic acoustic sensor array and generate optical signal data based on the returned optical signal; a second optical waveguide configured to direct the returned optical signal to the optical receiving device; an acoustic control unit configured to provide acoustic control data to an acoustic energy generation transducer array and receive acoustic signal data therefrom; and a processing system configured to receive the optical signal data and the acoustic signal data and generate a data output.

[0011] In some aspects, the technology described herein relates to a device comprising: a housing; a substrate mounted within the housing; a plurality of sensor optical fibers fixed to the substrate, each sensor optical fiber comprising: an optical waveguide; an optical sensor structure configured to: detect physical parameters and provide an optical signal corresponding to the physical parameters to the optical waveguide; and a plurality of acoustic energy generating transducers configured to generate acoustic energy.

[0012] In some aspects, the apparatus described herein relates to a device comprising: a sensor fiber comprising: an optical waveguide having a core and a cladding structure; and an optical sensor structure coupled to a first end of the optical waveguide and comprising at least one of an optical resonator, an optical interferometer, a facet end microstructure, and a polarization-sensitive structure, the optical sensor structure being configured to: detect an acoustic signal and provide an optical signal corresponding to the acoustic signal to the optical waveguide; perform multidimensional sensing of physical parameters; and provide an optical signal corresponding to the sensed physical parameters. Attached Figure Description

[0013] The accompanying drawings, incorporated herein by reference, form part of the specification and illustrate embodiments of systems, methods, and apparatuses for ultrasound sensing and imaging. Together with the specification, the drawings further explain the principles of the methods, systems, and apparatuses described herein and enable those skilled in the art to make and use the methods, systems, and apparatuses described herein. The drawings are provided to illustrate various features of the embodiments described herein and are not necessarily drawn to scale. In the drawings, similar reference numerals denote the same or functionally similar elements.

[0014] Figure 1 An optical sensor system for use with a fiber optic sensor is shown according to an embodiment of the present invention.

[0015] Figure 2 An optical sensor system for use with an optical fiber sensor is shown according to an embodiment of the present invention.

[0016] Figure 3A The sensor fiber optic cable includes the fiber optic sensor and the associated fiber optic cable.

[0017] Figure 3B The diagram shows a sensor fiber containing an optical waveguide and an optical resonator structure with a Fabry-Perotresonator as an optical sensor.

[0018] Figures 4A-4E Several variations of the optical resonator structure according to embodiments of the present invention are shown.

[0019] Figures 5A and 5B illustrate examples of optical sensor systems and fiber optic sensors according to embodiments of the present invention.

[0020] Figure 5C and 5D Examples of optical sensor systems and fiber optic sensors according to embodiments of the present invention are shown.

[0021] Figure 5E and 5F An example of a microfaceted structure according to an embodiment of the present invention is shown.

[0022] Figures 6A-6DD illustrate examples of optical sensor systems and fiber optic sensors according to embodiments of the present invention.

[0023] Figures 6E and 6F illustrate examples of optical sensor systems and fiber optic sensors according to embodiments of the present invention.

[0024] Figures 6G and 6H illustrate examples of optical sensor systems and fiber optic sensors according to embodiments of the present invention.

[0025] Figures 7A-7DExamples of manufacturing techniques that can be used to shape or process the ends of optical waveguides are provided.

[0026] Figures 8A-8D Examples of fabrication techniques that can be used to fabricate optical resonator structures at the ends of optical waveguides are provided.

[0027] Figures 9A-9B This demonstrates a method for thermal tuning applied to sensor optical fibers.

[0028] Figure 10 An embodiment of a sensor fiber comprising a multi-core optical waveguide is shown.

[0029] Figure 11A and Figure 11B A comparison is shown between sensor fibers arranged with forward and lateral optical sensors.

[0030] Figure 12 An embodiment of a sensor fiber providing rear-view acoustic detection capability is shown according to an embodiment of the present invention.

[0031] Figure 13 An embodiment of a sensor fiber that provides improved rear-view acoustic detection capability according to an embodiment of the present invention is shown.

[0032] Figure 14 The directional range of the optical resonant structure according to an embodiment of the present invention is shown.

[0033] Figure 15 An optical resonator structure incorporating a fiber Bragg grating according to an embodiment of the present invention is shown.

[0034] Figure 16 A method for operating an optical fiber-based sensor according to an embodiment of the present invention is shown.

[0035] Figure 17 A-17B shows a needle configured with sensor optical fibers according to an embodiment herein.

[0036] Figures 18A-18D show needles configured with sensor optical fibers according to embodiments herein.

[0037] Figure 19 The image shows an acoustic signal incident on the sensor fiber from a lateral direction.

[0038] Figures 20A-20B A close-up view of a needle with an integrated sensor fiber is provided according to an embodiment of the present invention.

[0039] Figure 20C-20D A needle containing a sensor fiber is shown according to an embodiment of the present invention.

[0040] Figure 21The distal end of a medical device according to an embodiment of the invention is shown, having a needle delivered via a catheter.

[0041] Figure 22 This illustrates the use of fiber-optic optical sensors in needle guidance or positioning according to embodiments herein.

[0042] Figures 23A-23B A catheter delivery needle with an optical fiber-based sensor is shown according to an embodiment herein.

[0043] Figure 24A and 24B An embodiment comprising a hybrid sensor probe and a hybrid sensor array is shown according to the embodiments described herein.

[0044] Figure 24C and 24D Additional embodiments of a hybrid sensor array transducer according to the examples herein are shown.

[0045] Figure 25A A concentric hybrid sensor array according to an embodiment herein is shown.

[0046] Figure 25B A linear hybrid sensor array according to an embodiment herein is shown.

[0047] Figure 25C A linear hybrid sensor array according to an embodiment herein is shown.

[0048] Figure 25D A linear hybrid sensor array according to an embodiment herein is shown.

[0049] Figure 25E An example of a structure in which a fiber optic sensor within a fixed array is incorporated into a hybrid sensor array, according to embodiments herein, is shown.

[0050] Figure 26A and 26B A hybrid sensor transducer probe according to an embodiment herein is shown.

[0051] Figure 27A and 27B An on-chip fiber optic sensor array according to an embodiment herein is shown.

[0052] Figure 28 A and 28B illustrate the structure of a hybrid array probe module according to embodiments herein.

[0053] Figure 29 A and 29B illustrate the structure of a hybrid array probe module according to embodiments herein.

[0054] Figure 30A and 30B illustrate embodiments of fiber optic sensor array transducers according to the examples herein.

[0055] Figure 31 A polarization-based fiber optic sensor array transducer according to an embodiment herein is shown.

[0056] Figure 32 A polarization-based fiber optic sensor array transducer according to an embodiment herein is shown.

[0057] Figure 33 A, 33B, and 33C illustrate the structure of a hybrid array probe module according to embodiments herein.

[0058] Figure 33 C shows a probe module viewed in the axial dimension according to an embodiment herein.

[0059] Figure 34 A polarization-based fiber optic sensor array transducer according to an embodiment herein is shown.

[0060] Figure 35 A, 35B, and 35C illustrate the structure of a hybrid array probe module according to embodiments herein.

[0061] Figure 35 C shows a probe module viewed in the axial dimension according to an embodiment herein.

[0062] Figure 36 A photoacoustic sensor system for use with an optical fiber sensor, according to an embodiment herein, is shown.

[0063] Figure 37 A photoacoustic sensor system for use with a hybrid sensor array, according to an embodiment herein, is shown.

[0064] Figure 38 A photoacoustic sensor system for use with a hybrid sensor array, according to an embodiment herein, is shown.

[0065] Figure 39 A and 39B illustrate the structure of a hybrid array probe module according to embodiments herein.

[0066] Figure 39 C provides an axial view of a probe module according to an embodiment herein.

[0067] Figure 40 A photoacoustic sensor system for use with a hybrid sensor array, according to an embodiment herein, is shown. Detailed Implementation

[0068] Non-limiting examples of various aspects and variations of the invention are described herein and illustrated in the accompanying drawings. The following detailed description is illustrative in nature only and is not intended to limit the invention or its application and use. Although the description of the invention is made in the context of fiber optic microsensor systems, methods, and apparatuses for ultrasound imaging and sensing, this disclosure should not be considered as limiting thereto. For example, although the methods may be discussed herein with regard to various medical procedures, embodiments of the invention may be adapted to other medical procedures, as well as other procedures or methods in other industries that may benefit from the sensing and imaging techniques described herein. Furthermore, various systems and apparatuses incorporating fiber optic microsensors are described. It should be understood that, as described herein, fiber optic microsensors can be integrated into and / or used with various systems and apparatuses not described herein. Modifications to the embodiments described herein may be made without departing from the spirit and scope of the invention. Therefore, the following detailed description is not intended to be limiting. Furthermore, there is no intention to be bound by any express or implied theory presented in the foregoing technical field, background art, summary of the invention, or the following detailed description.

[0069] This paper describes various structures based on their geometric properties. As discussed herein, all structures thus described may differ from the described shape due to tolerances of known manufacturing techniques. Unless otherwise specified, features described with the term "substantially" should be understood to be within a 5% margin of accuracy. For example, a feature described as "substantially parallel" may deviate from true parallelism by 5%.

[0070] This document describes systems, apparatuses, and methods for measuring physical parameters using fiber optic sensor structures. Broadly speaking, the fiber optic sensor structures described herein can undergo physical changes in response to external stimuli. These external stimuli may include, for example, changes in temperature and pressure, incident acoustic signals, etc. Such physical changes may include structural changes, changes in material properties or characteristics, etc., as described herein, which may result in measurable changes in the characteristic properties. For example, an optical signal incident on and reflected from the fiber optic sensor structure described herein may be affected by such a physical change. Therefore, the returned optical signal may have characteristics indicative of the physical change in the fiber optic sensor structure and thus of the environmental conditions or external stimuli that caused this physical change. In one example, changing the temperature of the fiber optic sensor structure described herein may result in a measurable difference in the returned optical signal, thus permitting the fiber optic sensor structure for temperature measurement. In another example, an acoustic signal incident on the fiber optic sensor structure described herein (e.g., a pressure change) may result in a measurable difference in the returned optical signal, thus permitting the fiber optic sensor structure for measuring acoustic responses (e.g., for ultrasonic imaging, tracking, positioning, etc.). These and other examples are described in more detail below. An example in which a given optical sensor structure can be used to measure multiple different physical parameters or external stimuli (e.g., temperature and pressure) can be called multidimensional sensing.

[0071] Disclosed are systems, apparatuses, and methods configured for ultrasound sensing and imaging using fiber optic microsensors or fiber optic sensor devices. In particular, the techniques described herein can track, visualize, and monitor (e.g., sense) objects during medical procedures, and generate ultrasound images. The fiber optic microsensor devices described herein incorporate optics positioned at the end of an optical fiber or at a designated location along its length, and are configured to detect acoustic signals, including ultrasound signals. As described herein, the sensor fiber includes an optical waveguide (e.g., an optical fiber) having a fiber optic microsensor device coupled at its end. As used herein, based on material systems such as fused glass, polymers, semiconductor / dielectric wafers, nanoimprint / 3D-printed polymers on different substrates, or any other optical signal channel, the term optical waveguide can refer to an optical fiber, fiber core, photonic integrated waveguide, planar waveguide, etc.

[0072] The technology described herein is compact and highly sensitive, making it suitable for a wide range of industrial applications as well as therapeutic and diagnostic medical applications. In non-medical applications, ultrasound is used in industrial applications such as defect detection, non-destructive testing, structural testing, and particulate sorting, as well as in geological applications including mining and drilling operations and underwater marine applications. These applications are consistent with the embodiments described herein. Therapeutic and diagnostic medical applications include ultrasound imaging and sensing (tracking, visualizing, guiding, and monitoring) of objects (e.g., needles, catheters, guidewires, cannulas, inserters, probes, etc.) during procedures such as needle insertion, biopsy, aspiration, delivery of drugs, biologics, anesthesia, or other therapeutic agents, catheter insertion, minimally invasive surgery, ablation, cauterization, object placement or movement, tissue preparation, cutting and / or slicing, and other medical procedures. The following disciplines are examples of procedures and applications that are widely used in diagnostic and therapeutic procedures and require precise guidance and imaging: anesthesia, cardiology, intensive care, dermatology, emergency medicine, endocrinology, gastroenterology, obstetrics and gynecology, hepatology, infectious diseases, interventional radiology, musculoskeletal medicine, nephrology, neurology, oncology, orthopedics, pain management, pediatrics, plastic and reconstructive surgery, urology, and vascular access.

[0073] In medical applications, object visualization, tracking, guidance, and location determination can be crucial aspects of performing medical procedures safely and reliably. Objects used for tracking, visualization, and location determination can include any type of medical device that moves or is positioned within the patient's body. For example, a physician visualizes and tracks a needle tip during a biopsy to ensure safety. In this case, precise needle tip visualization or tracking can help prevent or reduce unintentional damage to blood vessels, nerves, tissues, or internal organs. Similarly, visualization, tracking, or location of needles, endoscopes, cannulas, laparoscopic instruments, or other medical devices can be helpful when performing procedures such as, but not limited to: fluid aspiration; injection of drugs or biological agents into joints, tendons, and nerves; biopsies of fluid or soft tissue masses; aspiration and irrigation of calcifications; removal of tissues, organs, or foreign bodies; placement of stents, filters, valves, permanent, temporary, or biodegradable implants, shunts, or drainage tubes; anesthetic injections; insertion of vascular access devices for intravenous therapy; ablation procedures; and the performance of the Seldinger technique or catheter insertion for safe access to blood vessels and / or other organs. Visualization and tracking are advantageous in laparoscopic, minimally invasive, and open surgery, especially when visualization of an area is difficult due to limited access, intervention of tissues or organs, blood, or other fluids.

[0074] Several existing techniques use ultrasound imaging for guidance during medical procedures to visualize anatomical structures of interest, as well as to visualize, locate, and track inserted medical devices, particularly the distal and / or working portions of the device. However, several drawbacks exist associated with conventional ultrasound imaging techniques used in medical applications. Conventional techniques use imaging probes that emit ultrasound waves. Because needles and other inserted medical devices have smooth surfaces, incident ultrasound waves reflected from the surface can be diverted away from the receiving direction. This can make the reflected waves too weak to be easily detected, making it difficult to determine the device's position during the procedure. In some techniques, the medical device may have a rough surface, such as a recessed, etched, or coated surface, to increase visibility in ultrasound by increasing the echo of the medical device. However, even with these efforts, limitations remain. Ultrasound guidance tools may also be limited by their dependence on a specific incident angle, which restricts their ability to provide accurate visualization, especially for deeply placed devices. Due to this limitation, ultrasound guidance tools may be placed on surface locations, which limits their practicality, adoption, and cost-effectiveness as a deployable solution.

[0075] Compared to the proposed optical sensing technology, existing AEG transducers (such as, but not limited to, piezoelectric materials like lead zirconate titanate (PZT), ceramics, piezoelectric single crystals (e.g., PIN-PT, PIN-PMN-PT), polymer thick films (PTF), polyvinylidene fluoride (PVDF), capacitive micromechanical ultrasonic transducers (CMUT), piezoelectric micromechanical ultrasonic transducers (PMUT), and other materials known to those skilled in the art) suffer from at least two key acoustic performance limitations. First, achieving very high sensitivity requires transducers manufactured from specific AEG materials or with specific acoustic designs, but such transducers may only offer a relatively narrow acoustic response bandwidth. Second, as the size of the electrical component decreases relative to its resonant frequency, the acoustic response of the AEG transducer may be limited due to impedance mismatch. Therefore, for applications requiring small form factors (e.g., intravascular or intracardiac ultrasound, endoscopy, needle tracking, lung biopsy, sensing and monitoring, etc.), the signal-to-noise ratio (SNR) and bandwidth of small AEG transducers are reduced. Furthermore, highly directional responses can also be observed in some applications. Additionally, some AEG transducers and systems may be susceptible to electromagnetic interference, such as that caused by ablation tools, cauterization tools, or any other procedures or techniques that apply electrical energy to tissue. Furthermore, using electromechanical transducers at the distal end will involve conductive wires and associated components that require additional design and safety requirements and challenges.

[0076] In contrast, the fiber optic sensor according to this disclosure provides an ultrasonic receiver with high sensitivity, wide bandwidth, and wide acceptance angle, and eliminates the need for the electrical components required by electromechanical transducers. With these characteristics, the fiber optic sensor will be able to sense harmonic or scattered signals that are not detectable by existing technologies.

[0077] The fiber optic sensor of the present invention can also be used for multidimensional sensing of various physical parameters, such as environmental conditions, external stimuli, etc. The use of optical sensors as multidimensional sensors for sensing physical parameters alleviates many of the challenges associated with combining multiple sensors and their various components and connections. To achieve multidimensional sensing, measurement signals are generated from the responses of optical sensors, each of which can indicate a corresponding physical signal, physical parameter, external stimulus, environmental condition, etc. For example, a signal processor can generate a temperature measurement signal based at least in part on the resonant frequency shift caused by temperature changes (e.g., mode shift) in the optical sensor structure, and an acoustic measurement signal based at least in part on the optical power vibration caused by the incident acoustic signal. Multidimensional sensing can also be achieved by using multiple sensors, each responding differently to a different sensing target. The generation of measurement signals from the responses of optical sensors can involve decoupling the individual physical signals and / or jointly analyzing the responses of multiple sensors to determine the individual physical signals.

[0078] Furthermore, fiber optic sensors conforming to this disclosure can be compact, low-cost, and can contribute to scalable sensor systems. Embodiments of the invention include fiber optic sensors configured to detect acoustic signals and other physical parameters. Such fiber optic sensors can be positioned at the end of an optical fiber, near the end of an optical fiber, or at a diagnostic or therapeutic location on a medical device to generate a sensor fiber. The fiber optic sensor includes resonant structures, including but not limited to Fabry-Perot (FP) resonators, optical cavity resonators, whispering-gallery mode resonators, and photonic crystal resonators; optical interferometers, including but not limited to MZI, phase-shifting coherent interferometers, and self-mixing interferometers; acoustically responsive fiber endfaces; and acoustically responsive birefringent polarization sensors.

[0079] Acoustic-responsive fiber endfaces may include substrates suitable for incorporating various microstructures to enhance the response of fiber optic sensors to acoustic signals. Such microstructures may be: acoustic-responsive structures, such as metasurfaces containing patterns of small elements (e.g., having dimensions smaller than approximately one wavelength of the optical signal) arranged to alter the wavefront shape of the acoustic signal and maximize its detection; acoustically responsive low-dimensional materials with special optomechanical characteristics that are more easily deformable; and plasmonic structures patterned to amplify light-matter interactions. In embodiments, the microstructures described herein may also be used to detect additional physical parameters beyond the acoustic signal, as described herein. In addition to operating as optical sensors, fiber endface structures may be added to other fiber optic sensors described herein to further enhance the acoustic response. For example, metasurfaces may contain patterns of small elements arranged to alter the wavefront shape of the acoustic signal and maximize the collection of acoustic signals collected by other types of fiber optic sensors discussed herein, thereby improving the sensitivity of the fiber optic sensor. Adding low-dimensional materials to fiber endfaces can also improve sensitivity because such materials are more prone to deformation induced by acoustic waves, which translates into larger changes in the optical signal. By writing plasma patterns onto the end face of an optical fiber, the optical response to acoustic waves can be enhanced. This enhancement can be achieved by amplifying light-matter interactions through hot spots and resonances generated by these plasma patterns. As used herein, "low-dimensional" or "two-dimensional" features can refer to features with a thickness of less than 1 micrometer.

[0080] The aforementioned optical structures are configured to respond to acoustic signals (e.g., ultrasonic signals) and other physical parameters. Therefore, these optical structures may include acoustically responsive materials and / or acoustically responsive structures. As used herein, acoustic response refers to a structure or material configured to respond to an incident acoustic signal (e.g., an ultrasonic signal) in a manner that modulates the optical properties of the material or structure. The response to the acoustic signal in such a resonant, interferometer, or acoustically responsive fiber endface structure may be due to the photoelastic effect and / or physical deformation of the structure. When affected by an acoustic signal, the resonant, interferometer, or acoustically responsive fiber endface structure experiences mechanical stress and / or strain from the alternating pressure of the acoustic wave. This mechanical stress and / or strain can alter the optical properties of the optical sensor structure due to photoelastic effects and can also cause changes or deformations in the physical structure of the resonator. For polarization-based sensors, the polarization of the optical signal changes when the medium through which light passes is subjected to an acoustic signal. When coupled to a light source (e.g., a laser source, a broadband light source (e.g., a lamp or LED) or other suitable light source) via an optical waveguide (e.g., an optical fiber), the effect of the acoustic signal on the optical sensor structure can be measured because the light returning from the optical sensor structure via the optical waveguide changes.

[0081] Other physical parameters can be measured using similar techniques. For example, the optical properties of an optical sensor structure can be adjusted according to temperature and / or pressure, thus generating a signal that can be measured from changes in the light returned by the optical sensor structure. As discussed herein, for example, the resonant frequency of an optical sensor structure can change according to the temperature of the structure. In some embodiments, thermal tuning can be used to reduce or eliminate temperature changes in order to provide more accurate measurements of other stimuli, such as acoustic signals. However, in other embodiments, temperature changes can be measured based on resonant frequency shifts.

[0082] A given optical sensor structure can have different sensitivities for different physical parameters. For example, an optical sensor structure may have a first sensitivity to acoustic signals (pressure) and a first sensitivity to temperature changes. Using such a sensor, it can be difficult to measure acoustic signals or temperature without knowing and controlling the unmeasured element. If the pressure response signal depends on temperature, it can be difficult to measure the pressure response signal without controlling or knowing the temperature. When the pressure response signal changes, it can be difficult to determine whether the change is due to a temperature change, a pressure change, or both. Therefore, some embodiments discussed herein include techniques for controlling or understanding unmeasured physical parameters.

[0083] In other techniques, multidimensional measurement can be enabled by using multiple optical sensor structures with different sensitivities. In this example, a first optical sensor structure has a first sensitivity to an acoustic signal (pressure) and a first sensitivity to temperature changes. A second optical sensor structure has a second sensitivity to an acoustic signal and a second sensitivity to temperature changes. If the first and second sensitivities to temperature changes are different, then the difference in response signals between the first and second optical sensor structures when subjected to the same external stimulus can be considered attributable to temperature. Therefore, when the response signal changes, the portion of the change attributable to temperature and the portion attributable to pressure can be identified. A similar principle applies to cases where the first and second sensitivities to an acoustic signal (pressure) are different, or where the sensitivities to both temperature and acoustic signals are different. In other embodiments, a third, fourth, fifth, and / or more optical sensor structures may be included, which also have different sensitivities to at least one of temperature and acoustic signals.

[0084] Therefore, the embodiments described herein include an optical sensor array comprising a plurality of fiber optic sensors, wherein at least one optical sensor within the array has a sensitivity difference in terms of temperature response sensitivity, pressure response sensitivity, or both.

[0085] Within this disclosure, optical signals and light can be referred to as response acoustic signals or other physical parameters. It should be understood that this response is due to the interaction between the acoustic signal or physical parameter and the light transmission medium. Therefore, as discussed herein, so-called acoustically responsive materials or structures can respond to typical acoustic signals in an ultrasonic environment in a manner measured by optical signals according to embodiments of the invention, using the techniques described herein. In other embodiments, these materials or structures can be selected based on their response to other physical parameters such as temperature and / or pressure.

[0086] The fiber optic sensors discussed in this paper are sensitive to a variety of physical stimuli or parameters. Optical sensors intended for measuring acoustic signals may also be sensitive to other physical parameters such as temperature changes. Optical sensors can be designed to maximize sensitivity to anticipated stimuli or signals such as acoustic signals. However, such sensors remain sensitive to other stimuli, which can lead to errors or inaccuracies in measuring the anticipated / primary physical stimulus. By introducing additional sensors with different sensitivities, it is possible to better distinguish / identify which physical stimulus caused the signal shift.

[0087] Furthermore, in many applications, it is desirable to detect multiple types of physical stimuli or parameters. For example, in the field of medical technology, it can be advantageous for medical devices to have sensors capable of sensing multiple different physical parameters (e.g., simultaneous sensing in real-time or near real-time). For instance, an ablation catheter used in cardiovascular surgery may include a temperature sensor to measure the temperature of the treated tissue, and a force sensor to measure the force applied to the arterial wall during cardiac ablation. In some solutions, multiple types of sensors can be incorporated into a single device to monitor multiple different types of parameters, as a complement to or alternative to imaging. However, including more sensors may make it more difficult to fit the device into the desired form factor. Alternatively, including more sensors may present additional challenges in accommodating additional components (e.g., mechanical and / or electrical components) and connections to ensure the proper functioning of all the different sensors.

[0088] The use of optical sensors as multidimensional sensors for sensing physical parameters alleviates many of the challenges associated with combining multiple sensors and their various components and connections. To achieve multidimensional sensing, measurement signals are generated from the responses of optical sensors, each of which can indicate a corresponding physical signal. For example, a signal processor can generate a temperature measurement signal based at least in part on a resonant frequency shift (e.g., mode shift) and an acoustic measurement signal based at least in part on optical power vibrations. Multidimensional sensing can also be achieved by using multiple sensors, each responding differently to a different sensing target. Generating variations in measurement signals from optical sensor responses can involve decoupling the individual physical signals and / or co-analyzing the responses of multiple sensors to determine the individual physical signals.

[0089] Embodiments of the present invention include systems configured for use with fiber optic sensors. For example, systems according to this disclosure may include a light source (e.g., a laser source, a broadband light source (e.g., a lamp or LED) or other suitable light source), a light receiving device (e.g., a photodetector, etc.), optical devices (splitters, couplers, combiners, circulators, polarization-sensitive couplers, polarization analyzers, polarization controllers, frequency shifters, etc.), control devices, a computer processing unit, and other devices to facilitate the functionality of the fiber optic sensor. Furthermore, such systems according to this disclosure may include acoustic devices, such as transducers, probes, and hardware / software for their control. Systems according to this disclosure may further include medical systems and apparatuses, including all the means, systems, hardware, and software necessary to perform any medical procedure facilitated by the fiber optic sensor. It should be understood that the fiber optic sensor structures described herein can be used to measure both acoustic signals and other physical parameters, as described above, even if not explicitly stated for each individual embodiment. Furthermore, it should be understood that optical sensor structures of different sensitivities can be used to enhance multidimensional sensing within the fiber optic sensor arrays discussed herein.

[0090] Figure 1 An optical sensor system for use with an optical fiber sensor is shown. As used herein, the terms "optical fiber sensor" and "optical fiber-based optical sensor" refer to an optical sensor adapted and / or configured to detect acoustic signals, as described in further detail below. The optical sensor system 100A includes a light source 104, such as a laser, a light receiving device 103, such as a photodetector, one or more optical waveguides 105, an optical circulator 102, and an optical fiber sensor 101. In operation, the light source 104 supplies an initial optical signal 111 to the optical fiber sensor 101 via the optical waveguide 105 and the optical circulator 102. Optical components such as optical couplers may be used alternatively when discussing the optical circulator 102. The supplied initial optical signal 111 returns along the optical waveguide 105 through the optical fiber sensor 101. The returned optical signal 112 travels via the optical waveguide 105 through the optical circulator 102 and is received at the light receiving device 103. As discussed above, the acoustic signal and other physical parameters incident on the fiber optic sensor 101 may alter the optical properties of the fiber optic sensor 101 (which may include physical structure and optical material properties). Such changes in optical properties can be measured based on the changes in the returned optical signal 112, as discussed in more detail below.

[0091] Figure 2 An optoacoustic sensor system for use with fiber optic sensors is shown. The optoacoustic sensor system 200 includes a fiber optic sensor 101 or a fiber optic sensor array 201 (including multiple fiber optic sensors 101, such as...) Figure 2 The components, devices, hardware, and software used (as described in the text). Further references... Figure 2 This may specifically refer to the use of a single fiber optic sensor 101; however, it should be understood that in additional embodiments, the fiber optic sensor array 201 may be incorporated into the photoacoustic sensor system 200 in combination with any features discussed below, and any function belonging to the fiber optic sensor 101 may be further performed by the fiber optic sensor array 201. In embodiments, the fiber optic sensor array 201 may include fiber optic sensors 101 that have different sensitivities to one or more physical parameters, as discussed above. In embodiments, for example... Figure 2 As shown, the photoacoustic sensor system 200 may include hardware and components for facilitating the use of an ultrasonic transducer and / or an ultrasonic probe. The ultrasonic transducer may be used to generate and receive acoustic signals, or only to generate acoustic signals. The photoacoustic sensor system 200 may include a processing system 250, an optical subsystem 215, and an output device 208.

[0092] The processing system 250 may include a processing unit 209 and an image reconstruction or data unit 206. The processing unit 209 may include at least one computer processor, at least one non-transitory computer-readable storage medium, and suitable software instructions. The processing unit 209 is configured to provide control signals to the light source control unit 207, the light receiving device 203, and the acoustic control unit 222, and to receive information signals therefrom. The processing unit 209 can communicate with the light source control unit 207 (via control signals and information signals), thereby providing control over the optical signals provided to the fiber optic sensor 101. The processing unit 209 can communicate with the acoustic control unit 222 (via control signals and information signals), thereby providing control and reception of acoustic signals via the acoustic probe 245. The processing unit 209 is further configured to communicate with the light receiving device 203 to receive information signals associated with the optical signals received by the light receiving device 203. Therefore, the processing unit 209 is used to provide the required control signals and receive the acquired information signals in the photoacoustic sensor system 200.

[0093] Processing unit 209 also communicates with image reconstruction or data unit 206, which generates an image based on data and / or information acquired by processing unit 209. Image reconstruction or data unit 206 may generate an image based on data related to a medium, such as the human body, captured by fiber optic sensor 101 and acoustic probe 245. Distal end 231 of the medical device may include one or more of needles, catheters, guidewires, delivery devices, probes, cannulas, inserters, and / or any other devices or apparatuses configured for use within a patient's body. Image reconstruction or data unit 206 may be integrated within a system containing processing unit 209, and / or may be a separate system including at least one computer processor, at least one non-transitory computer-readable storage medium, and appropriate software instructions. Processing system 250 may provide control signals to output device 208 to provide data output. Output device 208 may include, for example, a display or a device including a display.

[0094] In some embodiments, when one or more of the optical sensors are used for multidimensional sensing to detect multiple physical signals such as temperature and pressure (e.g., detecting multiple different physical signals substantially simultaneously in real time or near real time), the processing unit 209 may alternatively or further include additional systems. For example, a measurement signal indicating the physical signals (e.g., temperature and pressure information) may be determined and then transmitted to a display or another output device 208 for real-time monitoring of other data related to the measurement area. As used herein, "real time" and "near real time" can refer to use cases where such data or information is continuously provided during the measurement process, but there may be processing or other delays.

[0095] In some embodiments, the output device 208 may further include additional systems, such as a medical procedure system configured to use the data as output. For example, the output device 208 may include an endoscopy system, a laparoscopy system, a robotic surgery system, a neurosurgical system, and may additionally include an interactive ultrasound imaging system. The output data may include information about the location of the distal end or working portion 231 of the medical device, sensed physical parameters, and acquired images of media in the area where the distal end 231 of the medical device is used / deployed, such as patient anatomy, tissues, other medical tools / devices, etc.

[0096] The optical subsystem 215 includes a light source control unit 207, a light source 204, optical devices 202A, 202B, 202C, and 202D, and a light receiving device 203. The light source control unit is configured to interface with and control the light source 204 to control the generation of an initial optical signal 211. The light source can generate continuous wave (CW) or pulsed light emission (stimulated emission, spontaneous emission, etc.). The initial optical signal 211 may contain coherent light, such as laser light, provided at one or more frequencies in one or more modes. The initial optical signal 211 may have a single frequency / wavelength, a series of frequencies / wavelengths, and / or a broadband light source. Therefore, the light source 204 may include a laser array configured to generate laser light at one or more frequencies in one or more modes. Additionally, the polarization of the supplied light can be controlled according to application requirements to optimize the detected signal level. The polarization state of the light can be controlled to be linearly polarized or circularly polarized at a specific angle. Linearly polarized light will respond optimally to a specific input ultrasonic direction, while circularly polarized light will respond to ultrasound in all directions. The polarization of light can be defined based on the output of the laser source, and the output polarization state can be controlled by an in-line fiber polarizer, a paddle-type fiber polarization controller, an in-line fiber polarization controller, or other types of polarization controllers. Optical devices 202A, 202B, and 202C can be configured to manipulate or influence the initial optical signal 211 received at the fiber optic sensor 101. The initial optical signal 211 can be provided at multiple wavelengths or across a wavelength spectrum. Optical device 202A may include, for example, a wavelength division multiplexing (WDM) device configured to multiplex multiple frequencies of the initial optical signal 211 provided by the light source 204 for simultaneous transmission via an optical waveguide 205 that guides the initial optical signal 211 to the fiber-optic end optical sensor 101. Optical device 202B can be a circulator with first, second, and third ports, wherein the first port is in optical communication with the light source via the wavelength division multiplexing (WDM) device 202A. In discussing the optical circulator 202B, optical components such as optical couplers can be used alternatively. An initial optical signal 211 can be routed through a second optical device 202B, which may be, for example, an optical circulator, and is configured to guide the initial optical signal 211 to an optical device 202C. The optical device 202C may include a WDM device configured to demultiplex the initial optical signal 211 provided to an optical fiber sensor 101, which may be part of an array 201, such that each of a plurality of optical fiber sensors 101 receives and subsequently outputs light of a different wavelength. The optical device 202C communicates optically with a second port of the second optical device 202B to split the initial optical signal into optical signals each having one of their associated wavelengths, and to combine the optical signals returned from the optical fiber sensor 101. These optical signals are then routed through a third port and an optical device 202D, which may include a WDM device, to an optical receiving device 203.

[0097] The initial optical signal 211 is received by the fiber optic sensor 101 (or the optical sensor 101 of the fiber optic sensor array 201 in some embodiments) and returned to the optical device 202C via one or more optical waveguides 205. The optical device may be further configured to multiplex the returned optical signal 212 (if needed) for transmission to the optical receiving device 203. The returned optical signal 212 is guided by the optical device 202C through the optical device 202B and toward the optical device 202D, which may be a WDM device configured to demultiplex the returned optical signal 212 for reception by the optical receiving device 203.

[0098] Optical device 202D can optically communicate with the third port of optical device 202B to receive the returned optical signal and divide it into individual wavelength components. For example, optical receiving device 203, which may be a photodetector array, can optically communicate with optical device 202D to receive the individual wavelength components of the returned optical signal, such that the phase shift or other changes of the detected individual wavelength components indicate the sensed acoustic signal or other physical parameters.

[0099] It should be understood that in embodiments where frequency multiplexing / demultiplexing is not required for the initial optical signal 211 and the returned optical signal 212, optical devices 202A and 202C may not be necessary. The optical receiving device 203 may include any suitable device configured to detect incident light, including, for example, a photodetector. The optical receiving device 203 may further include, but is not limited to, a photodiode. The optical receiving device 203 may optically communicate with the optical device 202D (e.g., a wavelength division multiplexing beam splitter) to receive the individual wavelength components of the returned optical signal 212, such that the phase shift, polarization change, or other changes of the detected individual wavelength components indicate the sensed acoustic signal or other physical parameters. The changes in the returned optical signal 212 can be converted (e.g., by processing unit 209 and / or by additional optical components such as polarization-sensitive couplers and / or frequency shifters) into data representing the sensed acoustic signal or other physical parameters (e.g., which can be further used to generate tissue / anatomical structures representing the medium into which the distal end 231 of the medical device is inserted in the area of ​​a diagnostic or therapeutic procedure and / or to identify the position of the distal end 231 of the medical device within the medium). In embodiments, these signals (the initial optical signal 211 and the returned optical signal 212) can undergo preprocessing, beamforming, and post-processing as described in the following documents.The following applications disclose various methods for ultrasonic beamforming and image processing: US Application 18 / 032953, filed April 20, 2023, entitled "Image Compounding for Mixed Ultrasound Sensor Array"; US Application 18 / 205081, filed March 7, 2023, entitled "Synthetic Aperture Imaging Systems and Methods Using Mixed Arrays"; US Application 18 / 091073, filed December 29, 2022, entitled "Acousto-Optic Harmonic Imaging with Optical Sensors"; PCT Application PCT / US2022 / 077762, filed October 7, 2022, entitled "Ultrasound Beacon Visualization with Optical Sensors". The following applications are cited in connection with the application: PCT application PCT / US2022 / 041250, filed August 23, 2022, entitled "Multi-Dimensional Signal Detection with Optical Sensor"; and PCT application PCT / US2022 / 018515, filed March 2, 2022, entitled "Acoustic Imaging and Measurements Using Windowed Nonlinear Frequency Modulation Chirp", each of which is incorporated herein by reference. The image and / or data representing the distal end 231 of the medical device (or the fiber optic sensor 101) can then be displayed to a user on an output device 208, which may include a computer display, etc. The image and / or data representing the distal end of the medical device may further be contained in the distal portion of the medical device within the acoustic transmission region.

[0100] As discussed above, the optical receiving device 203 communicates with the processing unit 209. The processing unit 209 receives from the optical receiving device 203 an information signal representing the returned optical signal 212 received at the optical receiving device 203. The processing unit 209 may also receive from the optical control unit 207 an information signal representing the initial optical signal 211 output by the light source 204. The processing unit 209 processes the information signal associated with the returned optical signal 212 (optionally compared to the information signal associated with the initial optical signal 211) to determine the acoustic environment and / or physical parameters at the fiber optic sensor 101, as further discussed below. The acoustic environment determination may include the detection, identification, and interpretation of acoustic signals incident on one or more fiber optic sensors 101 of the fiber optic sensor array 201. The processing unit 209 may determine the presence and nature of the acoustic signals incident on the fiber optic sensor 101. The physical parameter determination may include physical sensitivities (i.e., temperature or pressure) that cause at least one sensor to have a different acoustic sensitivity than another sensor, and then detecting, identifying, and interpreting what physical stimulus caused the signal shift.

[0101] Therefore, the fiber optic sensor 101 can be used to detect and / or receive acoustic signals (e.g., ultrasonic signals) and provide optical signals representing the acoustic signals or other physical parameters and corresponding to the acoustic signals or other physical parameters to an optical receiving device 203 via an optical receiving chain (e.g., optical devices 202C, 202B, 202D). The optical receiving device is configured to detect and / or receive the optical signals and provide electrical signals representing the optical signals and corresponding to the optical signals to a processing unit 209 for processing and interpretation. Therefore, the processing unit 209 can be configured to receive electrical signals representing the received acoustic signals and corresponding to the received acoustic signals, and process and interpret the electrical signals to reconstruct an image from the acoustic signals. For example, an ultrasonic image can be reconstructed using the delay-and-sum beamforming principle (a common method for reconstructing ultrasonic images). In delay-and-sum beamforming, the spatial distribution of the ultrasonic field amplitude in the volume of interest (image region) is reshaped according to the delay between the transmission, image pixels, and the receiver, and thus the received ultrasonic signal is reconstructed for the purpose of generating an image. In time-delay beamforming, signals are coherently superimposed at each image pixel location based on the delay.

[0102] The processing unit 209 may be further configured to receive an electrical signal representing and consistent with the sensed physical parameters, and to process and interpret the electrical signal to provide data or information related to the physical parameters, such as disclosed in PCT / US2022 / 041250, filed August 23, 2022, entitled "Multi-Dimensional Signal Detection with Optical Sensor" and incorporated herein by reference.

[0103] Processing unit 209 may further communicate with acoustic control unit 222. Acoustic control unit 222 may be configured to provide control data to acoustic probe 245 and / or acoustic transducer 221 and receive signal data therefrom. Acoustic probe 245 may be configured for use in vitro or in vivo and may include an AEG transducer or array of AEG transducers (or any other suitable acoustic transducer) configured to generate and / or receive acoustic signals, such as ultrasonic signals. Acoustic probe 245 may also include a hybrid array of both AEG transducers (or any other suitable acoustic transducers) configured to generate and / or receive acoustic signals and optical sensors configured to receive optical signals, such as those disclosed in U.S. Patent Publications US2022 / 0365036, US2023 / 0097639; US2022 / 0350022 and US2023 / 0148869, each of which is incorporated herein by reference. One or more array elements of the first type (e.g., AEG transducers) can be used to form a first image. In parallel, one or more array elements of the second type (e.g., optical sensors) are used to detect acoustic echoes that can be used to form a second image. The second image generated by the highly sensitive broadband optical sensor can be used alone or in combination with the first image to form a further improved image. Due to the high sensitivity and wide bandwidth of the optical sensor, the image generated by the optical sensor can have improved spatial resolution, improved penetration depth, improved signal-to-noise ratio (SNR), improved tissue harmonic imaging, and / or improved Doppler sensitivity.

[0104] Acoustic transducer 221 may be a component of a medical device system, configured for in vivo deployment within a medium in which a diagnostic or therapeutic procedure is being performed or will be performed. Acoustic transducer 221 may comprise an intracavitary or endocavitary transducer located on a catheter, cannula, etc., or may be an intraoperative transducer that allows for transducer positioning during minimally invasive surgery, such as on a laparoscopic instrument, positioned at the end of a robotic arm, or held by a surgeon, assistant, or other medical personnel for selective positioning. In embodiments, acoustic transducer 221 may be mounted on the same medical device as the distal end 231 of the medical device, for example, together with fiber optic sensor 101. In embodiments, acoustic transducer 221 may be mounted on one or more devices separate from the device at the distal end 231 of the medical device.

[0105] The in-body transducer 221 can be positioned on a catheter / endoscope / cannula and transmits acoustic waves outwardly capable of penetrating the region of interest in the medium, and can be referred to as a forward-looking probe, as is known in the art. Alternatively, the acoustic transducer 221 can emit acoustic waves laterally. For example, the transducer 221 can be part of a side-emission phased array used in IVUS applications. In another example, the transducer 221 can be used in a guide catheter with two side-by-side lumens, one lumen capturing the guidewire and the other working lumen extending distally without the guidewire lumen. Furthermore, the transducer 221 can transmit acoustic waves radially. For example, the transducer 221 can be included in an echo endoscope used for ultrasound imaging with radial (or fan-shaped), linear, curved (convex array), trapezoidal, or any other image format. A radial echo endoscope can provide a circumferential view perpendicular to the axis in the echo endoscope, or in other words, an image perpendicular to the inserted tube. Different ultrasound frequencies can be used to provide ultrasound imaging of distal and proximal structures. Radial echo endoscopes can provide 360-degree images of anatomical structures and can be used for screening, but may be limited to therapeutic applications, such as obtaining tissue samples. Curved, linear, or other suitable arrays can be used for therapeutic applications, such as tissue or fluid sample collection, cyst drainage, lesion / lymph node biopsy, and injections for pain management. In embodiments, transducer 221 may be incorporated into a curved echo endoscope that provides visualization within a range depending on the curve radius and allows for real-time insertion of needles / therapeutic devices. In such embodiments, the ultrasound view may be colinear or plane-aligned with the endoscope axis. In other embodiments, transducer 221 may be incorporated into a transverse array and provide images in a plane perpendicular to the endoscope axis.

[0106] In other procedures, a movable intraoperative transducer can be positioned on the end of a robotic arm or other tool (such as the bkMedical Rob12C4) or simply held by a medical professional during the procedure. Additionally, certain cannulas and endoscopes can have forward-emitting transducers 221 for allowing sound to penetrate the area in front of the cannula, catheter, or endoscope, such as in craniotomy transducers.

[0107] A typical ex vivo transducer 221 or probe 245 can be positioned on the patient's skin surface, for example, for general imaging or for specific procedures such as needle guidance, needle positioning or needle placement.

[0108] Processing unit 209 is configured to use information signals received by fiber optic sensor 101 from acoustic probe 245 or acoustic transducer 221 (and any other acoustic signal generators that can be connected to or communicate with photoacoustic sensor system 200) to sense, track, and monitor the distal end 231 of the medical device, generate ultrasound images of anatomical structures in the surgical area, and provide data related to the sensed physical parameters. In embodiments, fiber optic sensor 101 or sensor array 201 is used to receive / detect acoustic signals generated by acoustic probe 245 and / or acoustic transducer 221, as well as scattered signals and tissue harmonics. Imaging of the medium can be achieved by processing unit 209 based on the difference between the acoustic signals output or transmitted by acoustic probe 245 and / or acoustic transducer 221 and the corresponding acoustic signals received and / or detected by acoustic probe 245 and / or acoustic transducer 221 and fiber optic sensor 101. The detected signals may include detected scattered signals and tissue harmonics. The portion of the medium through which the acoustic signal generated by the acoustic probe 245 and / or acoustic transducer 221 travels can be imaged based on the detected acoustic signal.

[0109] Fiber optic sensor 101 (or sensor array 201) receives acoustic signals transmitted from acoustic probe 245 and / or acoustic transducer 221. Based on the signals received from fiber optic sensor 101, the position of fiber optic sensor 101 (and therefore the position of the distal end 231 of the medical device) can be calculated by triangulation (e.g., based on receiving one or more acoustic signals transmitted from a known source) and / or by coherent image formation. Further details can be found in: U.S. Provisional Application No. 63 / 522,994, co-filed, entitled "Transponder Tracking and Ultrasound Image Enhancement," filed June 23, 2023; and U.S. Application No. 18 / 382,984, entitled "Transponder Tracking and Ultrasound Image Enhancement," filed October 23, 2023. The position of the fiber optic sensor 101 can be overlaid on the ultrasound image of the anatomical structure to determine the relative position of the fiber optic sensor 101 with respect to the known positions of the acoustic probe 245 and / or acoustic transducer 221. Furthermore, the ultrasound image of the surrounding anatomical structure can be coherently reconstructed based on a combination of acoustic signals received by the fiber optic sensor 101 and by one or more of the acoustic probe 245 and / or acoustic transducer 221. Such a combination can produce better image quality than images formed using the acoustic probe 245 and / or acoustic transducer 221 alone.

[0110] In embodiments that track, sense, and monitor the distal end 231 of the medical device, the photoacoustic sensor system 200 may include a plurality of acoustic probes 245 fixed in place or whose positions are tracked. For example, tracking, sensing, determining, and monitoring the position and movement of the distal end 231 of the medical device can be achieved by identifying timing and / or directional differences between multiple acoustic signals detected by the fiber optic sensor 101 and the acoustic transducer 221.

[0111] It should be understood that, as an example, the following is provided Figure 2 The photoacoustic sensor system 200 is configured as shown. Different configurations may be used without departing from the scope of this disclosure. For example, different arrangements of optical devices 202A / B / C / D, different numbers and arrangements of fiber optic sensors 101, and fiber optic sensor arrays 201 may be used. In embodiments, the light source control unit 207 and the acoustic control unit 222 may be incorporated into or integrated within the processing system 250. Additional combinations of components of the photoacoustic sensor system 200 may be selected as needed to achieve the functions described herein.

[0112] Figure 3AThe sensor fiber optic cable includes the fiber optic sensor and the associated fiber optic cable. Figure 3A The illustrated device may include a sensor fiber 301. The sensor fiber 301 may be an optical fiber with a fiber optic sensor disposed at its end. The sensor fiber 301 includes an optical waveguide 311 comprising a core 312 and a cladding structure 313. The optical waveguide 311 is configured to transmit or carry light therein, for example, within the core 312. The core 312 is surrounded and protected by the cladding structure 313. The optical waveguide 311 may be substantially cylindrical along its length, and / or may have another suitable shape. The core 312 may be substantially at the center of the cladding structure 313. In embodiments, the optical waveguide 311 may be an optical fiber and may contain any material common to optical fibers. For example, the core 312 may contain silica glass, a polymer, or other suitable materials. For example, the material of the cladding structure 313 may be selected to respond to changes in pressure or strain induced by ultrasound. Pressure or strain induced by ultrasound will introduce deformation or a change in refractive index, resulting in a change in the optical signal passing through the optical fiber. For example, when used as an ultrasonic sensor, a larger change results in higher sensitivity and a better detection limit. The cladding material may have at least one associated material property, wherein the at least one material property may be a refractive index (RI) lower than that of the core 312. Material properties, such as the Young's modulus and photoelastic coefficient of the core, cladding material, and encapsulation structure, which may be the same or different materials, can be customized according to the application. A smaller Young's modulus and a larger photoelastic coefficient may be preferred for improving ultrasonic sensitivity and acoustic responsiveness. As used herein, a material sensitive or responsive to acoustic signals may refer to, for example, a material having a relatively small Young's modulus (E), a relatively high photoelastic coefficient, and / or a relatively large refractive index (n) compared to silica materials. As used herein, a relatively small Young's modulus may refer to a Young's modulus less than 3.0 GPa, less than 2.0 GPa, less than 1.2 GPa, or in the range between 1.2 and 0.8 GPa. A relatively high photoelastic coefficient C (i.e., () can refer to something greater than C = 2 * 10 12The photoelasticity coefficient is 1 / Pa. A relatively large refractive index can refer to a refractive index greater than approximately 1.46 for optical signals in the range of approximately 300 nm to 2000 nm. Materials can be selected to enhance, improve, or optimize the ability of the optical structures discussed herein to detect acoustic signals. Because the optical structures described herein are configured to detect acoustic signals (e.g., ultrasonic signals), the materials used to construct them can be selected to maximize or increase the sensitivity of the structure's optical properties to the incident acoustic signal. For example, materials with a lower Young's modulus require less stress to deform. In some applications, increased deformation may be undesirable. However, increased deformation in response to the incident acoustic signal can amplify or increase the detectable change in the optical signal passing through an optical structure undergoing greater deformation. Similarly, an increase in photoelasticity is desirable in the optical structures described herein, but may be undesirable in different structures configured for different purposes. As discussed herein, materials can be further selected based on their sensitivity to other physical parameters such as temperature.

[0113] It should be understood that the core 312 can be any suitable type of core, such as those made of silica, silicon, optically transparent polymers, etc. As a non-limiting example, if the core 312 is made of silica (SiO2), then the cladding material can be MY-133, a low-refractive-index optical coating manufactured by MY Polymers Ltd. of Israel, or BIO-133, also a low-refractive-index optical coating manufactured by MY Polymers Ltd. of Israel. As another non-limiting example, if the core is silicon with a higher RI than silica, then the cladding structure 313 can be polyvinylidene fluoride (PVDF), polystyrene (PS), parylene, benzocyclobutene (BCB), MY-133, or BIO-133.

[0114] The optical waveguide 311 can be configured for single-mode (SM) or multimode (MM) transmission, depending on the form factor and laser and sensor wavelength tuning requirements, as SM fibers are relatively small. For example, a single-mode fiber configured to operate in the 1550 nm band may have a cladding diameter of 50 μm and a core diameter (D) > 4.2 μm. Such fibers can be polarization-maintaining fibers. Multimode fibers configured to operate in the 1550 nm band may have a core diameter of 50 μm-60.5 μm and a cladding diameter of 125 μm. In embodiments, polymer fibers (e.g., PMMA, polystyrene) can be used. Compared to typical glass fibers, such fibers can have a larger diameter and a larger minimum bending radius. In other embodiments, photonic crystal fibers (with hollow structures / periodic patterns) can be used.

[0115] An optical resonator structure 321 is disposed at the end (e.g., the distal end) of the sensor fiber 301. This disclosure generally relates to fiber optic end sensors. Such fiber optic end sensors may include optical sensing structures, such as the optical resonator structure 321 disposed at its end (e.g., the distal end). The optical resonator structure 321 is coupled to the end of an optical waveguide 311 and may include an optical resonator, such as a Fabry-Perot (FP) resonator, a whispering-gallery mode resonator, a microring, a microtoroid, a helical resonator, or a photonic crystal resonator integrated therein. In addition to the optical resonator, the optical resonator structure 321 and other optical resonator structures described herein may also include additional structures and components configured to facilitate the function of the optical resonator, as described below. The optical resonator is configured to receive a first optical signal (e.g., light) supplied to it via the optical waveguide and return a second optical signal along the optical waveguide. The second optical signal may correspond to and represent an acoustic signal incident on the optical resonator structure 321. As discussed above, the incident acoustic signal can cause physical deformation and / or changes in the material properties of the optical resonator structure 321. Therefore, the optical signal provided by the optical resonator structure along the optical waveguide 311 can be altered by, affected by, or otherwise indicate or represent the acoustic signal, and can thus be used to characterize the incident acoustic signal.

[0116] The sensor fiber 301 may further include an encapsulation structure 314, which may include, for example, an outer coating, a shield, a protective outer layer, and / or a fiber sheath. The encapsulation structure 314 is configured with a first portion 314A surrounding the optical waveguide 311 and a second portion 314B at least partially surrounding the optical resonator structure 321. The encapsulation structure 314 may contain a polymer, such as parylene, MY-133, BIO-133, or other suitable polymers that are sensitive to or responsive to acoustic signals, as discussed above. The acoustic impedance of the encapsulation structure 314 can be selected to match the impedance of the optical resonator structure 321 to enhance the detection sensitivity of the acoustic signal. As used herein, “matched impedance” can refer to the selection of materials and / or structures with matched acoustic impedances, as is generally known to those skilled in the art of medical ultrasound, where acoustic impedances differing by no more than 20% provide an acceptable match. Closer matching of acoustic impedances results in better transmission of the acoustic signal (e.g., a smaller portion of the acoustic signal is reflected), thus producing higher sensitivity. In embodiments, the first portion 314A surrounding the optical waveguide 311 and the second portion 314B, which at least partially surrounds the optical resonator structure 321, may comprise different materials selected for different purposes. For example, the first portion 314A may comprise an acoustically transparent material, such as having an acoustic impedance selected to increase matching and thereby minimize the reflection of acoustic signals. The second portion 314B may comprise an acoustically responsive / sensitive material, as discussed above, to increase the response to incident acoustic signals in regions of the optical resonator structure 321. Unless otherwise explicitly stated, all encapsulation structures discussed herein may comprise properties similar to those of the encapsulation structure 314, including the first and second portions comprised of different materials selected for different purposes.

[0117] An optical resonator structure 321 is disposed at the end of an optical waveguide 311 and can therefore be referred to as an optical fiber end sensor. The cladding structure 313 may have a first diameter, and the optical resonator structure 321 may have a second diameter. The first and second diameters may or may not be substantially the same. Depending on the application, it may be advantageous to have the optical fiber have substantially the same dimensions or to make the sensor significantly larger than the optical fiber, for example, it may also be an asymmetrical bulb-shaped structure. Increased dimensions can further enhance the acoustically sensitive surface area of ​​the sensor, thereby increasing overall sensitivity. As discussed above, considering the need for small form factors in some medical applications, the sensor fiber 301 can be compact, in some examples where the first and / or second diameters are less than 200 micrometers, less than 175 micrometers, less than 150 micrometers, less than 130 micrometers, less than 100 micrometers, or less than 85 micrometers.

[0118] Figure 3BA sensor fiber comprising an optical waveguide and an optical resonator structure is shown, the optical resonator structure having a Fabry-Perot type resonator as an optical sensor. Sensor fiber 351 is an example of sensor fiber 301 and may include any of the features of sensor fiber 301 described above. Sensor fiber 351 comprises an optical waveguide 371 having a core 352 and a cladding structure 353. Core 352 may have a diameter in the range of 7 to 12 micrometers, or approximately 9 micrometers. These dimensions are provided only as examples and do not limit the dimensions and diameters covered by embodiments of this disclosure. Sensor fiber 351 may comprise an encapsulation structure 354 encapsulating the optical waveguide 371 and an optical resonator structure 361 disposed at the end of the optical waveguide 371, the encapsulation structure may, for example, include an outer coating, a protective outer layer, and / or an optical fiber sheath. Encapsulation structure 354 may be a multilayer structure, comprising, for example, an inner layer 355 and an outer layer 356. The inner layer 355 may comprise gold or any suitable reflective material for light waves, while the outer layer 356 may comprise parylene, MY-133, BIO-133, or other suitable acoustically transparent protective layers. The encapsulation structure 354 may comprise a first portion 354A encapsulating or surrounding the optical waveguide 371 and a second portion 354B encapsulating or surrounding the optical resonator structure 361. The encapsulation structure 354 may have features similar to those of the encapsulation structure 314, comprising the first and second portions of different materials. The optical resonator structure 361 may be configured with a Fabry-Perot resonator as an optical resonator 362. The optical resonator 362 includes a distal reflective surface 364 and a proximal reflective surface 363 disposed on either side of the optical cavity 365. The distal reflective surface 364 and the proximal reflective surface 363 may be constructed from any suitable reflective material. Figure 3B As shown, the distal reflective surface 364 and the proximal reflective surface 363 are formed and integrally formed with the inner layer 355 of the encapsulation structure 354, and are therefore formed of gold or other suitable reflective material. Figure 3B As shown, the distal reflective surface 364 may be curved, and the proximal reflective surface 363 may be substantially flat. This arrangement is merely an example, and the distal and proximal reflective surfaces 364 / 363 may have different shapes and / or configurations. Figures 4A-4E Some additional examples are provided. In other embodiments, the distal reflecting surface 364 and the proximal reflecting surface 363 may be formed of different materials and / or may be structures separate from the encapsulation structure 354. An optical cavity 365 is disposed between the distal reflecting surface 364 and the proximal reflecting surface 363. As used herein, the term "optical cavity" refers to the volume occupied by a material that provides minimal attenuation of light passing through it (e.g., having a high Q factor typically greater than 1000). The mass (Q) factor is a dimensionless parameter describing the amount of damping within a resonator. A higher Q factor corresponds to a more sensitive resonator.

[0119] In optics, the Q factor of a resonant cavity is given by the following equation:

[0120] ,

[0121] in It is the resonant frequency, and E is the energy stored in the cavity. This refers to the dissipated power. The optical Q factor is equal to the ratio of the resonant frequency to the cavity resonant bandwidth. The average lifetime of a resonant photon in the cavity is proportional to the cavity's Q factor. Therefore, a high Q factor indicates low damping, and photons within the cavity have a long lifetime.

[0122] The Q factor, as well as any other determinations of sensitivity and responsiveness, are ultimately limited by the choice of material used for the fiber core. Conventional Fabry-Perot interferometers can be homogeneously formed from a single material, such as silica throughout the structure. For example, while silica possesses excellent light transmission capabilities, it does not have the same excellent acoustic sensitivity. Although many materials with excellent acoustic sensitivity are known, these materials may not be suitable substitutes for silica, etc., in the fiber core. This invention employs a resonant actuator to utilize the acoustic sensitivity found in other materials.

[0123] Optical cavity 365 can be composed of suitable materials, such as polymers. Polymer materials with high acoustic transmittance, such as MY-133 or BIO-133, can be used to enhance the sensitivity of the optical resonator structure, as discussed above. Optical resonator structure 361 can be configured to detect acoustic signals. Acoustic signals incident on the optical resonator structure, such as on the distal reflecting surface 364, the proximal reflecting surface 363, and / or optical cavity 365, can cause these structures to vibrate and / or undergo other physical deformations, which may alter or affect their optical properties. Furthermore, the material properties of these structures can be altered due to photoelastic effects, and thus further alter the optical properties. Therefore, the returned optical signal provided by optical resonator structure 361 to optical waveguide 371 (e.g., in response to an optical signal supplied via optical waveguide 371) can indicate or represent the acoustic signal incident on optical resonator structure 361. More specifically, the phase shift of light in the detected sensor beam indicates the sensed acoustic signal. Using a polarization-based sensor, the polarization analyzer interprets the phase shift / delay between different polarization components to generate a signal indicating the sensed acoustic signal. As discussed above, the optical resonator structure 361 can be further configured to detect additional physical parameters.

[0124] Figures 4A-4E Several variations of the optical resonator structure 361 according to an embodiment of the present invention are shown. Figure 4AAn optical resonator structure 361 is shown, which has a near-side reflecting surface 363 and a far-side reflecting surface 364, which are substantially flat and substantially parallel at either end of a substantially cylindrical optical cavity 365. Figure 4B An optical resonator structure 361 is shown, which has a near-side reflecting surface 363 that is substantially flat and substantially square relative to the optical waveguide 371 and a far-side reflecting surface 364 that is concave relative to the optical cavity 365. Figure 4C An optical resonator structure 361 is shown, which has a near-side reflecting surface 363 that is convex relative to the optical cavity 365 and a far-side reflecting surface 364 that is concave relative to the optical cavity. Figure 4D An optical resonator structure 361 is shown, which has a near-side reflecting surface 363 that is concave relative to the optical cavity 365 and a far-side reflecting surface 364 that is substantially flat and substantially square relative to the optical waveguide 371. Figure 4E An optical resonator structure 361 is shown, which has a near-side reflecting surface 363 and a far-side reflecting surface 364, both of which are concave relative to the optical cavity 365.

[0125] Figure 5A illustrates an optical sensor system for use with a fiber optic sensor according to an embodiment herein. Figure 5B illustrates an interferometer-based optical sensor according to an embodiment herein. The optical sensor system 100B of Figure 5A is configured for use with an interferometer-based fiber optic sensor 101B, as shown in Figure 5B.

[0126] Fiber optic sensor 101B may include a fiber optic end sensor having an interferometer-based acoustic sensor. Fiber optic sensor 101B may include a sensor fiber 301A having an interferometer-based fiber optic end sensor structure 321A disposed at its end, for example, at the end of an optical waveguide 311A. In addition to those mentioned, sensor fiber 301A may include features and structures consistent with those of sensor fiber 301. The interferometer-based fiber optic end sensor structure 321A may include, for example, a Mach-Zehnder (MZ) type interferometer. The interferometer-based fiber optic end sensor structure 321A is coupled to the end of the optical waveguide 311A. The interferometer-based fiber optic end sensor structure 321A may include additional structures and components configured to facilitate the functionality of the interferometer-based fiber optic end sensor, as described below. The interferometer-based fiber optic end sensor is configured to receive a first optical signal (e.g., light) supplied to it via the optical waveguide 311A ​​and to return a second optical signal along the optical waveguide 311A. The second optical signal can correspond to and represent the acoustic signal incident on the interferometer-based fiber optic end sensor structure 321A. The incident acoustic signal can cause physical deformation and / or changes in material properties of the interferometer-based fiber optic end sensor structure 321A. Therefore, the optical signal provided by the interferometer-based fiber optic end sensor structure 321A along the optical waveguide 311A ​​can be modified by, affected by, or otherwise indicate or represent the acoustic signal, and can therefore be used to characterize the incident acoustic signal.

[0127] The interferometer-based fiber optic end-sensor structure 321A may include an acoustically responsive polymer portion 317A, which comprises parylene or other suitable polymers sensitive to acoustic signals and / or other physical parameters. The acoustic impedance of the polymer portion 317A can be selected to match the acoustic impedance of the encapsulation structure of the sensor fiber 301A (e.g., differing by within 1%, 5%, 10%, or 20%) to enhance the sensitivity of the fiber optic end-sensor structure 321A, as described above. A distal reflective surface 364A is disposed at the distal end of the fiber optic end-sensor structure 321A and can be constructed of any suitable material, such as gold. As shown in Figure 5B, the distal reflective surface 364A is formed of gold and is integral with the polymer portion 317A.

[0128] An optical fiber end sensor structure 321A is disposed at the end of an optical waveguide 311A, and therefore can be referred to as an optical fiber end sensor. The optical waveguide 311A ​​may have a first diameter, and the optical fiber end sensor structure 321A may have a second diameter. The first and second diameters may be substantially the same, and / or may have a ratio in the range of 1.05 to 0.95, a ratio in the range of 1.02 to 0.98, or a ratio in the range of 1.01 to 0.99. As discussed above, the sensor fiber 301A may be compact, for example, wherein the first and / or second diameters are less than 200 micrometers, less than 175 micrometers, less than 150 micrometers, less than 130 micrometers, less than 100 micrometers, or less than 85 micrometers.

[0129] Optical sensor system 100B is configured for use with interferometer-based fiber optic sensor 101B. Optical sensor system 100B may include a light source 104, such as a laser; a light receiving device 103, such as a photodetector; one or more optical waveguides 105; an optical circulator 102; one or more frequency shifters 106; and one or more couplers 107A / B. In operation, the light source 104 supplies an initial optical signal 111A to the fiber optic sensor 101 via optical waveguide 105, through coupler / decoupling device 107A, and through optical circulator 102. The supplied initial optical signal 111A returns along optical waveguide 105 through fiber optic sensor 101. The returned optical signal 112 travels via optical waveguide 105 through optical circulator 102 and coupler / decoupling device 107B, and is received at light receiving device 103. Coupler / decoupler 107A is used to guide a portion of the initial optical signal 111A as a reference optical signal 111B through frequency shifter 106 to coupler / decoupler 107B, where it can be combined with the returned optical signal 112 for detection and comparison at optical receiver 103. As discussed above, the acoustic signal incident on fiber optic sensor 101 alters the optical properties of fiber optic sensor 101 (including physical structure and optical material properties). Such changes in optical properties can be measured based on the change in the returned optical signal 112 compared to the reference optical signal 111B. Furthermore, changes in physical parameters (e.g., temperature or pressure changes) can also alter optical properties in a measurable manner.

[0130] Figure 5C and 5DAn embodiment of an optical fiber sensor is shown, comprising an optical fiber endface configured to provide or enhance acoustic detection capability. Optical fiber sensor 101C and optical fiber sensor 101D each comprise at least an optical waveguide 311, a fiber core 312, a cladding structure 313, and an encapsulation structure 314. Optical fiber sensor 101C includes an optical sensor structure 329C comprising an acoustically responsive polymer portion 397 and a surface substrate 398A located at its distal end. Optical fiber sensor 101D includes an optical sensor structure 329D comprising the acoustically responsive polymer portion 397, a surface substrate 398B disposed between the polymer portion 397 and the core 312 and the cladding structure 313, and a distal end reflective surface 394 disposed at the distal end of the polymer portion 397.

[0131] In the fiber optic sensor 101C, a surface substrate 398A is disposed at the distal end of the fiber optic sensor 101C. An optical sensor structure 329C is formed from a polymer portion 397 and the surface substrate 398A. The surface substrate 398A includes one or more surface structures 399A, as shown in the cross-sectional view. The surface structure 399A may include: acoustically responsive microstructures, such as a metasurface containing a pattern of small elements arranged to alter the wavefront shape of an acoustic signal and maximize the detection of the acoustic signal; acoustically responsive low-dimensional materials having optomechanical features selected to optimize the acoustic response, such as being more easily deformable upon receiving an acoustic signal and exhibiting a greater material response to the acoustic signal; and plasmonic structures patterned to amplify light-matter interactions, as described herein. The plasmonic structures can locally amplify incident light due to their plasmonic resonances. The surface structure 399A operates as the optical sensor described herein. During operation, a supplied optical signal 1111 is reflected from the surface substrate 398A and returned to the system as a returned optical signal 1121. Because the surface structure 399A is acoustically responsive, the returned optical signal 1121 is modified by changes in the surface structure 399A caused by the incident acoustic signal. In an embodiment, the plasmonic resonance induced in the plasmonic metasurface acting as the surface structure 399A or the Mie resonance induced in the dielectric metasurface acting as the surface structure 399A can be altered (e.g., shifted) by the incident acoustic signal, making the modification of the returned optical signal 1121 detectable. The returned optical signal 1121 can then be interpreted using any of the systems described herein.

[0132] In the fiber optic sensor 101D, a surface substrate 398B is disposed between the polymer portion 397 and the core 312 and cladding structure 313. The optical sensor structure 329D is formed by the polymer portion 397, the surface substrate 398B, and the distal reflective surface 394. The surface substrate 398B includes one or more surface structures 399B, as shown in the cross-sectional view. The surface structures 399B may include acoustically responsive microstructures, similar to those described above with respect to surface structures 399A. The surface structures 399B are used to enhance, improve, or otherwise modify the acoustic response of the optical sensor structure 329D. During operation, the supplied optical signal 1111 is reflected from the distal reflective surface 394 and returned to the system as a returned optical signal 1121. The polymer portion 397 and the distal reflective surface 394 are acoustically responsive, and the returned optical signal 1121 is modified according to the acoustic signal incident on these structures. Because the surface structure 399B is acoustically responsive and both the supplied optical signal 1111 and the returned optical signal 1121 pass through the surface substrate 398B, the returned optical signal 1121 is further modified by the changes in the surface structure 399B caused by the incident acoustic signal. In embodiments, the surface structure 399B can be designed and / or selected to optimize coupling (e.g., reduce signal loss) and / or achieve critical coupling (e.g., eliminate signal loss) for the optical sensor structure 329D. The increased coupling in the optical sensor structure 329D is used to increase the amplitude of the optical signal responding to the incident acoustic signal. Therefore, the returned optical signal 1121 can exhibit a higher signal-to-noise ratio. Furthermore, the incident acoustic signal that deforms the surface structure 399B can also be used to change the degree to which the surface structure 399B modifies the coupling in the optical sensor structure 329D, thereby providing another aspect of the returned optical signal 1121 modified by the incident acoustic signal for interpretation. The returned optical signal 1121 can then be interpreted by any of the systems described herein. Therefore, the surface substrate 398B can be used to enhance, improve, or otherwise modify the acoustic response of the optical sensor structure 329D.

[0133] Surface structures 399A and 399B in Figure 5C and 5D The diagram shows its integration into fiber optic sensors 101C and 101D. Such surface substrates are not limited to use with optical sensors having interferometer-based structures and operations of fiber optic sensors 101C and 101D, but can be integrated into any of the fiber optic sensors discussed herein.

[0134] Figure 5E An example of a plasma metasurface is shown, and Figure 5F An example of a dielectric metasurface is shown. For example... Figure 5EAs shown, the optical fiber 500 may include a plasmonic metasurface 511 disposed at the end of an optical waveguide 502 having a core 501. The plasmonic metasurface 511 may be disposed on the end of the optical fiber 500 within a region defined by the core 501. As shown, for example, the plasmonic metasurface 511 may be disposed in a square pattern, or it may be disposed in any other suitable pattern. The plasmonic metasurface 511 may exhibit plasmonic resonance when struck by an optical signal from the core 501. The deformation caused by the incident acoustic signal alters the plasmonic resonance and allows for the detection and decoding of the acoustic signal, as discussed herein. The plasmonic metasurface 511 may contain various metals, particularly noble metals such as gold. Alternatively, the plasmonic metasurface 511 may be a thin film surface having a height of less than 50 micrometers, less than 40 micrometers, less than 30 micrometers, less than 20 micrometers, or less than 10 micrometers. In other embodiments, the plasmonic metasurface 511 may be a low-dimensional or two-dimensional surface with a height of less than 1 micrometer. In the lateral dimension, the features of the plasmon metasurface 511 can be small, having a lateral dimension D (e.g., width and / or length) smaller than the wavelength of the optical signal used by the sensor (e.g., less than 600 nm, less than 400 nm, less than 200 nm, etc.). The lateral dimension of the features of the plasmon metasurface 511 can also refer to the spacing between the features. Figure 5F A dielectric metasurface 512 is shown, which can be similarly positioned within the core 501 at the end of the optical waveguide 502 of the optical fiber 550. The dielectric metasurface 512 can be arranged in a strip or rectangular shape, such as... Figure 5F As shown, or arranged in any other suitable shape. The dielectric metasurface 512 can be configured to exhibit Mie resonance when struck by an optical signal. The Mie resonance can be altered by the incident acoustic signal, thereby allowing the detection and decoding of the acoustic signal. In embodiments, the dielectric metasurface 512 may comprise a dielectric material, such as silicon, titanium oxide, etc. In embodiments, the dielectric metasurface 512 can be sized in a manner similar to that of the plasmonic metasurface 512, as discussed above.

[0135] Figure 6A illustrates an optical sensor system for use with an optical fiber sensor according to embodiments herein. Figure 6B illustrates a polarization-based optical sensor according to embodiments herein. Optical sensor system 100B is configured for use with a polarization-based optical fiber sensor 101C. Optical fiber sensor 101C may include an optical fiber end sensor having a polarization-based acoustic sensor. Optical fiber sensor 101C may include a sensor fiber 301B having a polarization-based optical fiber end sensor structure 321B disposed at its end, for example, at the end of an optical waveguide 311B. In other embodiments, as discussed below, the polarization-based optical fiber end sensor structure 321B may be disposed at any location along the sensor fiber 301B. In addition to those mentioned, sensor fiber 301B may include features and structures consistent with those of sensor fiber 301. Sensor fiber 301B includes an encapsulation structure 314C, which may include, for example, an outer coating, a protective outer layer, and / or an optical fiber sheath. The encapsulation structure 314C may include a material selected to have a relatively high acoustic impedance mismatch with the cladding structure of the sensor fiber 301B. Therefore, the incident acoustic signal can be reflected at the location of the sensor fiber 301B covered by the encapsulation structure 314C. The polarization-based fiber-to-optic sensor structure 321B can be exposed through a window 320B defined by the absence of the encapsulation structure 314C, and may include a polymer portion 317B comprising an acoustically responsive polymer and a distal reflective surface 364B configured to reflect the initial optical signal 111 as a reflected optical signal 112. The polarization-based fiber-to-optic sensor structure 321B is configured to receive a first optical signal (e.g., light) supplied to it via the optical waveguide 311B and return a second optical signal along the optical waveguide 311B. The second optical signal may correspond to and represent the acoustic signal incident on the polarization-based fiber-to-optic sensor structure 321B. The incident acoustic signal can cause physical deformation and / or changes in material properties of the polarization-based fiber-to-optic sensor structure 321B. Therefore, the optical signal provided by the polarization-based fiber optic end sensor structure 321B along the optical waveguide 311B can be altered, influenced, or otherwise indicated or represented by the acoustic signal, and thus can be used to characterize the incident acoustic signal. In the polarization-based fiber optic end sensor structure 321B, the incident acoustic signal induces stress in the polymer portion 317B, which causes one or more of birefringence and rotation of the polarization of the light passing through the polymer portion 317B, thereby altering the polarization of the light carried by the optical waveguide 311B, which can be detected and analyzed by the optical sensor system 100B discussed below. In embodiments, the polarization-based fiber optic sensor 101C (and all polarization-based sensors discussed and described herein) can be further configured to detect, identify, and / or sense physical parameters, such as pressure and temperature, as described herein.

[0136] Optical sensor system 100B includes a light source 104, such as a laser, a light receiving device 103, such as a photodetector, one or more optical waveguides 105, an optical circulator 102, and an optical fiber sensor 101B. In operation, the light source 104 supplies an initial optical signal 111 to the optical fiber sensor 101B via the optical waveguide 105 and the optical circulator 102. The supplied initial optical signal 111 returns along the optical waveguide 105 through the optical fiber sensor 101B. The returned optical signal 112 travels via the optical waveguide 105 through the optical circulator 102, through a polarization analyzer 108, and is received at the light receiving device 103. The use of the polarization analyzer 108 allows determination of the polarization difference between the initial optical signal 111 and the returned optical signal 112. As discussed above, the acoustic signal incident on the optical fiber sensor 101B alters the optical properties of the optical fiber sensor 101B (including physical structure and optical material properties) and causes a change in the polarization of the returned optical signal 112. Such polarization changes can be measured based on the difference between the returned optical signal 112 and the initial optical signal 111 determined by the photodetector.

[0137] In this embodiment, the angular sensitivity of the polarization-based fiber optic end sensor structure 321B may be affected by differences in the polarization of the initial optical signal 111. Depending on the polarization of the initial optical signal 111, the angle of the incident acoustic signal to which the polarization-based fiber optic end sensor structure 321B is most sensitive can be changed, such as... Figure 6C As shown. Therefore, in this embodiment, the control system associated with the optical sensor system 100B can be configured to adjust or optimize the polarization of the initial optical signal 111, for example, changing it from input polarization state 1 to input polarization state 2 to increase acoustic sensitivity. These polarization states are provided only as examples and can be changed or configured as needed for operation, as discussed below. Figure 6CThe diagram shows the directions in which input polarization state 1 and input polarization state 2 are most sensitive to the incoming acoustic signal. Solid arrows correspond to the direction most sensitive to input polarization state 1, and dashed arrows correspond to input polarization state 2. Therefore, the lobes of the polarization states provide the highest acoustic sensitivity. Thus, the input polarization state can be selected and implemented to align with the expected direction of the acoustic signal or the direction requiring the highest acoustic sensitivity. This allows the optical sensor system 100B to optimize the performance of the fiber optic end sensor structure 321B according to the direction of the incoming acoustic signal. The angular sensitivity of the polarization-based fiber optic end sensor structure 321B is not dependent on the structure of the fiber optic end sensor structure 321B. In an embodiment, polarization-maintaining fiber can be used. After the polarization state is selected and implemented, it is maintained by the optical signal. In an embodiment, an adjustable fiber component can be used to provide an adjustable polarization state. In an embodiment, the polarization state can be adjusted during use, taking into account changes in conditions (e.g., movement of the acoustic transducer 221 generating the acoustic signal and / or movement, rotation, etc. of the fiber optic end sensor structure 321B). Other benefits of the polarization-based fiber optic end sensor structure 321B may include a simplified sensor structure and no wavelength locking requirement.

[0138] Figure 6DAnother embodiment of a fiber-optic optical sensor according to an embodiment of the present invention is shown. The sensor fiber 301C may be an optical fiber configured in a manner similar to sensor fiber 301, comprising an optical waveguide including a core and cladding structure, as described herein. Sensor fiber 301C may have an fiber-end sensor structure 321C disposed at its end. Fiber-end sensor structure 321C may comprise any of the fiber-end sensor structures discussed herein, including optical resonator structures, interferometer structures, acoustic response fiber endface structures, and polarization-based structures, and may be configured to measure and / or detect acoustic signals and other physical parameters. Sensor fiber 301C may further comprise an encapsulation structure 314C configured to reflect incident acoustic signals and a window 320C representing a gap or exposed area without the encapsulation structure 314C. Window 320C may expose a polarization-based optical sensor structure 322C, as discussed, for example, with respect to FIG. 6B. In this embodiment, the polarization-based optical sensor structure 322C is formed by the cladding structure and core of the optical fiber and is part of the optical fiber. In other words, the polarization-based optical sensor structure 322C can be defined by exposure to the incident acoustic signal generated due to the absence of an acoustic shield at the window 320C, rather than by any additional structure within the optical fiber. The sensor fiber 301C may include any number of windows 320C and polarization-based optical sensor structures 322C arranged along its length. Therefore, the sensor fiber 301C may include multiple optical-based acoustic sensor structures, including both fiber end sensor structures 321C and polarization-based optical sensor structures 322C configured for intermediate fiber locations. In other embodiments, the window 320C may be sufficiently sized along the length of the fiber such that it will operate as a line sensor rather than a point sensor, as will be discussed in more detail below. The line sensor may be a straight-line sensor or a curved receiver. In other embodiments, the sensor fiber 301C may be configured with one or more polarization-based optical sensor structures 322C arranged along its length, but without any fiber end sensor structures 321C.

[0139] Each of the fiber optic end sensor structure 321C and the polarization-based optical sensor structure 322C can be used to facilitate both imaging and tracking, as described herein. In embodiments, for example, the polarization-based optical sensor 322C can be configured in terms of size / shape to facilitate imaging, tracking, or both. For example, a longer polarization-based optical sensor structure 322C can act as a line sensor to increase image quality, and the line can be a straight line or a curve. In another example, multiple polarization-based optical sensor structures 322C can be used to facilitate tracking methods (e.g., multiple sensors along the device can help with orientation determination).

[0140] In some embodiments, the polarization window portion may also function as an optical fiber sensor for detecting scattered acoustic signals and / or tissue harmonics. When the optical fiber sensor is positioned within the imaging region of interest, it can receive weak harmonic or scattered acoustic signals that cannot propagate over long distances. The optical fiber can transmit an optical signal corresponding to the received acoustic signal to a system processor (e.g., processing unit 209). The system processor can use the received optical signal to reconstruct an ultrasound image of the anatomical structures surrounding the sensor using a time-delayed superposition beamforming method or other suitable image reconstruction method, as discussed in more detail in U.S. Provisional Application No. 63 / 522,994, filed June 23, 2023, entitled "Transponder Tracking and Ultrasound Image Enhancement," and in US Application No. 109835-1394978, filed concurrently on October 23, 2023, entitled "Transponder Tracking and Ultrasound Image Enhancement." Using this data, the system processor can generate images of higher quality than those generated solely based on pulses emitted and received by the acoustic probe. In one embodiment, the system processor can construct the image based solely on optical signals received from one or more fiber optic sensors. In another embodiment, the optical signals received from one or more fiber optic sensors can be used in combination with acoustic signals received by a conventional ultrasonic probe.

[0141] This principle is in Figure 6DD This is shown in more detail below. For example... Figure 6DD As shown, an acoustic probe 601 can be used to transmit an acoustic signal 620 to a region of interest. For imaging purposes, the acoustic probe 601 can be used as a conventional acoustic probe to detect the reflection of the acoustic signal 620. These images can be enhanced by additional information obtained by one or more fiber optic sensors. The fiber optic sensor 612 of the sensor fiber 602 can correspond to any of the fiber-optic end optical sensor structures discussed herein and can receive the acoustic signal 622. The acoustic signal 622 can be generated by reflection, scattering, and / or tissue harmonics. Figure 6DD As shown, acoustic signal 622 is generated from point 621 within the region of interest. Fiber optic sensor 612 can be configured to receive acoustic signal 622 from any direction, as discussed herein. Sensor fiber optic cable 603 can be configured to act as a polarization-based optical sensor, as discussed herein, and can receive acoustic signal 622 from directions laterally to the axis of sensor fiber optic cable 603. As used herein, "lateral" means all directions not parallel to the axis of sensor fiber optic cable 603. Figure 6DDAs shown, the acoustic signal 622 can be received from any direction at any exposed portion along its length by the sensor optical fiber 602, as per [reference to...]. Figure 6D As discussed. Furthermore, such as regarding Figure 6C The discussion and such Figure 6C As shown, the polarization of the sensor fiber 602 can be selected or adjusted to suit the expected or desired radial incident angle of the acoustic signal 622. Figure 6DD The sensor fiber 604 is further illustrated, which can be bent within the imaging region of interest. Similar to the sensor fiber 603, the sensor fiber 604 can detect incident acoustic signals 622 incident laterally to, substantially laterally to, the axis of the sensor fiber 604 or from any direction. When the sensor fiber 604 is positioned within a medium (e.g., within the human body during a medical procedure), detecting lateral signals at multiple points along the length of the sensor fiber 604 can enhance the ability to track and / or locate the sensor fiber 604. For example, as... Figure 6DD As shown in (b), multiple signals incident along the length of the sensor fiber 604 can enhance the ability to determine the location of different portions of the sensor fiber 604 along its length and thus identify the location of the entire sensor fiber 604, not just the tip region. For example, as Figure 6DD As shown in (c), multiple signals incident along the length of the sensor fiber 604 can enhance the ability to determine the position of different parts of the sensor fiber 604 with greater accuracy and thus identify the curvature of the sensor fiber 604.

[0142] Figures 6E and 6F illustrate optical sensor systems for use with fiber optic sensors according to embodiments herein. Figure 6F illustrates an optical resonator-based optical sensor configured for use with a multi-core fiber according to embodiments herein. The optical sensor system 100D of Figure 6E is configured for use with a multi-core fiber optic sensor 101D based on an optical resonator, as shown in Figure 6F. In other embodiments, other optical sensors discussed herein, including, for example, interferometer-based sensors, can be employed in multi-core fiber optic systems.

[0143] Fiber optic sensor 101D may include a fiber optic end sensor having an acoustic sensor based on an optical resonator, as described herein. Fiber optic sensor 101D may include a sensor fiber 301D having an optical resonator-based fiber optic end sensor structure 321D disposed at its end, for example, at the end of an optical waveguide 311D. In addition to those mentioned, sensor fiber 301D may include features and structures consistent with those of sensor fibers 301 and 351. The optical resonator-based fiber optic end sensor structure 321D is coupled to the end of the optical waveguide 311D. The optical resonator-based fiber optic end sensor structure 321D may include an optical resonator sensor 322D, and further include additional structures and components configured to facilitate the functionality of the optical resonator sensor 322D, as described below. The optical fiber end sensor 322D based on an optical resonator, schematically shown in Figure 6F, can be waveguide-coupled, such that it is configured to receive an initial optical signal 111 (e.g., light) supplied to it via a first optical core 313D of sensor fiber 301D, and to provide a returned optical signal 112 along a second optical core 312D of sensor fiber 301D. The second optical signal may correspond to and represent the acoustic signal incident on the optical fiber end sensor structure 321D, or it may correspond to and represent other physical parameters associated with the optical fiber end sensor structure 321D. The incident acoustic signal or other physical parameters can cause physical deformation and / or changes in material properties of the optical fiber end sensor structure 321D. Therefore, the optical signal provided by the optical fiber end sensor structure 321D along the second optical core 312D can be modified by, affected by, or otherwise indicate or represent the acoustic signal, and can therefore be used to characterize the incident acoustic signal.

[0144] The optical resonator-based fiber optic end-sensor structure 321D may include an acoustically responsive polymer portion 317D, comprising parylene or other suitable acoustically sensitive polymers. The acoustic impedance of the polymer portion 317D can be selected to match the acoustic impedance of the encapsulation or cladding structure 314D of the sensor fiber 301D (e.g., differing by within 1%, 5%, 10%, or 20%) to enhance the sensitivity of the optical resonator-based fiber optic end-sensor structure 321D, as described above.

[0145] An optical fiber end-sensor structure 321D is disposed at the end of an optical waveguide 311D, and therefore can be referred to as an optical fiber end-sensor. An encapsulation or cladding structure 314D may have a first diameter, and the optical fiber end-sensor structure 321D may have a second diameter. The first and second diameters may be substantially the same, and / or may have a ratio in the range of 1.05 to 0.95, a ratio in the range of 1.02 to 0.98, or a ratio in the range of 1.01 to 0.99. As discussed above, the sensor fiber 301D may be compact, for example, wherein the first and / or second diameters are less than 200 micrometers, less than 175 micrometers, less than 150 micrometers, less than 130 micrometers, less than 100 micrometers, or less than 85 micrometers. If the fiber diameter is extremely small, increasing the diameter of the optical fiber sensor end can further enhance the acoustic sensitivity.

[0146] Optical sensor system 100D is configured for use with resonator-based fiber optic sensor 101D. Optical sensor system 100D may include a light source 104, such as a laser, a light receiving device 103, such as a photodetector, one or more optical waveguides 105, and a multi-core fiber fan-out coupler 109. In operation, the light source 104 supplies an initial optical signal 111 to fiber optic sensor 101D via optical waveguide 105 and multi-core fiber fan-out coupler 109. The supplied initial optical signal 111 travels via a first optical core 313D to the optical resonator-based fiber end sensor structure 321D, where it may be affected by an incident acoustic signal, and is then returned by a second optical core 312D as a returned optical signal 112. The returned optical signal 112 travels via optical waveguide 105 through fan-out coupler 109 to be received at light receiving device 103. As discussed above, the acoustic signal incident on fiber optic sensor 101D alters the optical properties of fiber optic sensor 101D (including physical structure and optical material properties). Such changes in optical properties can be measured based on the returned optical signal 112 to measure the properties and characteristics of the incident acoustic signal. In the embodiment of FIG6E, for example, it is not necessary to provide the initial optical signal 111 to the optical receiving device 103 to measure the changes in optical properties, because the parameters of the initial optical signal 111 are known to the system.

[0147] A multi-core fiber fan-out coupler 109 is used to couple a single-core optical waveguide 105 to a multi-core optical waveguide 311D. Therefore, the initial optical signal 111 and the returned optical signal 112 can travel in individual optical cores within the multi-core optical waveguide 311D. Compared to the optical sensor system 100B, the use of the multi-core fiber fan-out coupler 109 and the multi-core optical waveguide 311D in the optical sensor system 100D may eliminate the need for an optical circulator. Such a design can be advantageous for several reasons. For example, compared to an optical circulator, the multi-core fiber fan-out coupler 109 of the optical sensor system 100D can be smaller, lighter, and / or cheaper, which allows for greater flexibility when incorporating the fiber optic sensor 101D into a device or apparatus. In embodiments, other suitable configurations of optical couplers for coupling single-core fibers to multi-core fibers can replace the multi-core fiber fan-out coupler 109.

[0148] Figures 6G and 6H illustrate optical sensor systems for use with fiber optic sensors according to embodiments herein. Figure 6H illustrates an optical resonator-based optical sensor configured for use with a pair of single-core optical fibers according to embodiments herein. The optical sensor system 100E of Figure 6G is configured for use with a dual-fiber sensor 101E based on an optical resonator, as shown in Figure 6H. In other embodiments, other optical sensors discussed herein, including, for example, interferometer-based sensors, can be employed in dual-fiber-based systems.

[0149] Fiber optic sensor 101E may include a fiber optic end sensor having an acoustic sensor based on an optical resonator, as described herein. Fiber optic sensor 101E may include a sensor fiber 301E having a fiber optic end sensor structure 321D based on an optical resonator disposed at its end. In addition to those mentioned, sensor fiber 301E may include features and structures consistent with those of sensor fibers 301 and 351.

[0150] The fiber optic sensor 101E may include a dual-fiber structure. The fiber optic sensor 101E may include a first optical waveguide 311E having a first fiber core 313E and a second optical waveguide 315E having a second fiber core 312E. Each of the first optical waveguide 311E and the second optical waveguide 315E may be a separate optical fiber and may each have a separate cladding structure 314E. The first optical waveguide 311E and the second optical waveguide 315E may be coupled together. For example, the first optical waveguide 311E and the second optical waveguide 315E may be coupled via an adhesive or other bonding agent.

[0151] The optical resonator-based fiber optic end sensor structure 321E is coupled to the ends of both the first optical waveguide 311E and the second optical waveguide 315E. The optical resonator-based fiber optic end sensor structure 321E may include an optical resonator sensor 322E, as well as additional structures and components configured to facilitate the functionality of the optical resonator sensor 322E, as described below. The optical resonator-based fiber optic end sensor 322E, schematically shown in FIG. 6H, may be waveguide-coupled, such that it is configured to receive an initial optical signal 111 (e.g., light) supplied to it via a first optical core 313E of the first optical waveguide 311E, and to provide a returned optical signal 112 along the second optical core 312E of the second optical waveguide 315E. The returned optical signal 112 may correspond to and represent an acoustic signal incident on the optical resonator-based fiber optic end sensor structure 321E, and / or may correspond to and represent other physical parameters associated with the fiber optic end sensor structure 321E. Incident acoustic signals and / or other physical parameters can cause physical deformation and / or changes in material properties of the optical resonator-based fiber optic end sensor structure 321E. Therefore, the optical signal provided by the optical resonator-based fiber optic end sensor structure 321E along the second optical core 312E can be altered by, affected by, or otherwise indicate or represent the acoustic signal, and thus can be used to characterize the incident acoustic signal. In the embodiment of FIG. 6G, for example, it is not necessary to provide the initial optical signal 111 to the optical receiving device 103 to measure changes in optical properties, because the parameters of the initial optical signal 111 are known to the system.

[0152] The optical resonator-based fiber optic end-sensor structure 321E may include an acoustically responsive polymer portion 317E, comprising parylene or other suitable acoustically sensitive polymers. The acoustic impedance of the polymer portion 317E can be selected to match the acoustic impedance of the encapsulation (or cladding) structure of the sensor fiber 301E (e.g., differing by within 1%, 5%, 10%, or 20%) to enhance the sensitivity of the optical resonator-based fiber optic end-sensor structure 321E, as described above.

[0153] Optical sensor system 100E is configured for use with resonator-based fiber optic sensor 101E. Optical sensor system 100D may include a light source 104, such as a laser, a light receiver 103, such as a photodetector, and one or more optical waveguides 105. The one or more optical waveguides 105 may be structurally bonded to each other to form a first optical waveguide 311E and a second optical waveguide 315E of sensor fiber 301E, and may be separable to couple with the light source 104 and the light receiver 103. In embodiments, a coupler or other device may be used to facilitate this coupling. In operation, the light source 104 supplies an initial optical signal 111 to the fiber optic sensor 101E via the optical waveguide 105. The supplied initial optical signal 111 travels via the first optical waveguide 311E to the optical resonator-based fiber end sensor structure 321E, where it may be affected by an incident acoustic signal, and is then returned by the second optical waveguide 315E as a returned optical signal 112. The returned optical signal 112 travels via optical waveguide 105 to be received at optical receiver 103. As discussed above, the acoustic signal incident on the fiber optic sensor 101E alters the optical properties of the fiber optic sensor 101E (including its physical structure and optical material properties). Such alterations in optical properties can be measured based on the returned optical signal 112.

[0154] The dual-fiber design of the 301E fiber sensor eliminates the need for circulators or multi-core fan-out couplers. Such a design can be advantageous for several reasons. For example, eliminating multi-core fiber fan-out couplers and optical circulators can provide a smaller, lighter, and / or cheaper system, which allows for greater flexibility when incorporating the 101E fiber sensor into a device or equipment.

[0155] Figures 7A-7D Examples of manufacturing techniques that can be used to shape or process the ends of optical waveguides are provided. Figure 7A The diagram illustrates a method for processing the end of an optical waveguide with a CO2 laser to achieve a concave near-side reflective surface, for example, to accommodate a near-side reflective surface that is concave relative to the optical cavity. Figure 7B The diagram illustrates a method for wet etching the ends of an optical waveguide to achieve a concave near-side reflective surface, for example, to accommodate a near-side reflective surface that is concave relative to the optical cavity. Figure 7C The end of a mechanically polished optical waveguide is shown to achieve a concave near-side reflective surface, for example, to accommodate a near-side reflective surface that is concave relative to the optical cavity. Figure 7D The diagram illustrates a method for processing the end of an optical waveguide with a CO2 laser to achieve a concave near-side reflective surface, for example, to accommodate a near-side reflective surface that is concave relative to the optical cavity.

[0156] Figures 8A-8D Examples of fabrication techniques that can be used to fabricate optical resonator structures at the ends of optical waveguides are provided. Figure 8AA micromolding method that can be used to form optical resonator structures is shown. Figure 8B A dip-coating method that can be used to form optical resonator structures is shown. Figure 8C A conformal coating method that can be used to form optical resonator structures is shown. Figure 8D A dip-coating method that can be used to form optical resonator structures is shown.

[0157] Figure 9A A method for thermal tuning applied to a sensor fiber optic cable is illustrated. Interferometer-based fiber optic sensors (or other optical sensor structures according to embodiments of the invention) can benefit from wavelength tuning mechanisms to maintain the interferometer-based fiber optic sensor at an optimal operating point. The optimal operating point can be based on the resonance of the optical sensor structure. In embodiments, the resonant wavelength of the optical sensor structure and the operating wavelength of the laser providing the optical signal can be selected, adjusted, or determined together to optimize or maximize optical readings. The resonant wavelength of the optical sensor structure and the operating wavelength of the laser can be selected, adjusted, or determined such that the operating wavelength of the laser matches the ramp of the resonant peak of the optical sensor structure. Specific positions on the ramp of the resonant peak can vary according to sensor design and application-specific requirements. Specific operating positions on the ramp of the resonant peak affect the dynamic range and sensitivity of the optical sensor structure. In embodiments, the operating position (e.g., wavelength) can be selected to have response amplitudes in the range of 10%-90% of the resonant depth, 10%-30% of the resonant depth, 30%-50% of the resonant depth, 50%-70% of the resonant depth, or 70%-90% of the resonant depth. Therefore, wavelength tuning according to embodiments of the present invention may be achieved by tuning the operating wavelength of the laser or the resonant wavelength of the optical sensor.

[0158] The wavelength tuning mechanism according to an embodiment of the invention may include, for example, a heated or tuned laser or an external tuner configured to tune by applying mechanical stress and / or electrothermal heating. While a tunable laser in the back-end system can provide tunability, individual tunability (local tuning) at the sensing front end is also desirable because it allows for (1) a cheaper laser without wavelength tunability and (2) a scalable sensor array with a shared laser. Figure 9AThis paper illustrates a method for local tuning using photothermal tuning, which requires no additional wiring. In an embodiment, light from a working laser and a heating laser (at different wavelengths) is guided together by an optical fiber. The working laser wavelength can be selected to optimize sensing performance, and at least one structure at the end of the optical fiber (e.g., portion of optical resonator structure 321, encapsulation structure 314, etc.) is absorptive at the heating wavelength. By tuning the power of the heating laser, the local temperature in optical resonator structure 321 changes, and thus the temperature-sensitive optical transmittance of the fiber optic sensor is tuned to better match the wavelength of the working laser. Therefore, the heating laser is operated to adjust the temperature of optical resonator structure 321 according to the wavelength of the working laser. The heating laser can be continuous wave or pulse-width modulated. In an embodiment, sensor fiber 301C can have a double-clad structure. Any of sensor fibers 301 / 301A / 301B can incorporate features of sensor fiber 301C. Sensor fiber 301C may include an inner cladding structure 313A and an outer cladding structure 313B. If the heating wavelength is longer than the core's cutoff wavelength, then an outer cladding structure 313B can be introduced, which is optimized for operational optical transmission.

[0159] exist Figure 9B In another local tuning method shown, an external tuner 902 can be provided to replace the heated laser for tuning the sensor transmission by applying, for example, mechanical stress or electrothermal heating. Figure 9B A sensor fiber 301, for example, with an optical resonator structure 321 is shown. Any suitable sensor fiber and fiber optic sensor can be used with an external tuner 902. The external tuner 902 may include, for example, piezoelectric and / or electrothermal elements outside the optical cavity, which can be configured to apply pressure (i.e., compression) or heat to the optical resonator structure 321. This may require additional cables, wires, traces, and / or microheater printed flexible circuitry along the length of the fiber optic sensor to enable the external tuner. The additional structure will not affect the optical properties of the sensor as long as the sensor optical path (within dashed box 368) in the optical resonator structure 321 is not interrupted.

[0160] In another example, the optical resonator structure 361 may have an operating wavelength that is adjusted to be more closely aligned with the wavelength of the light source (e.g., a source laser). When multiple fiber optic sensors are arranged in an array, the ability to individually calibrate and fine-tune each fiber optic sensor within the array provides the potential to drive and synchronize the operation of each sensor in the array. This synchronization also allows the user to drive multiple (≥2) fiber optic sensors with a single source laser and simultaneously capture signals from multiple sensors. Such a feature is advantageous when constructing sensor arrays for imaging. In this process, feedback loops can be employed to monitor and adjust heat sources or stresses to fine-tune the operating wavelength of the sensors, thereby ensuring their alignment with the source laser. By simultaneously capturing multiple data points or collaboratively analyzing complex imaging patterns, the synchronized operation of the sensor array ensures robust data interpretation.

[0161] Figure 10 An embodiment of a sensor fiber comprising a multi-core optical waveguide is shown. The sensor fiber 801 may include any or all of the features of sensor fibers 301 and 351, as described above. The sensor fiber 801 may include an optical waveguide 811 and an optical resonator structure 321. The optical waveguide 811 includes a plurality of cores 312 within a cladding structure 313, for example, 2, 3, 4, 5, 6, 7, 8, 9, etc.

[0162] Figure 11A and Figure 11B A comparison is shown between sensor fibers arranged with forward-facing and lateral optical sensors. When integrating sensors into a device, the environment in which the sensor will be used and the direction of the transmitted sound beam are important considerations. For example, some applications of the optical sensors disclosed herein may benefit from a forward-facing arrangement, while others may benefit from a lateral arrangement.

[0163] Figure 11A Showing according to Figure 3A The sensor fiber 351 shown here, with a Fabry-Perot resonator acting as part of an optical resonator structure, is an optical resonator. The optical resonator structure 361 is arranged in a forward configuration. In this forward configuration, the surface or facet of the optical resonator structure 361 configured to receive and detect acoustic signals (in the optical resonator 362, this surface could be a distal reflecting surface 364 or a proximal reflecting surface 363) is arranged such that the acoustic response surface or facet is oriented in the same direction as the direction in which the sensor fiber 351 extends. The sensor fiber 351 and the acoustic response surface or facet may share an axis. As discussed above, the optical resonator structure 361 can be further configured to detect, measure, and / or respond to other physical parameters.

[0164] Figure 11BA sensor fiber 1001 is shown, in which a Fabry-Perot resonator acts as an optical resonator as part of an optical resonator structure 1021, arranged to laterally capture incident acoustic signals. The sensor fiber 1001 may include all the features of sensor fibers 301, 351, and 801 (even if not shown). The sensor fiber 1001 may include one or more cores 1012, one or more cladding structures 1013, an encapsulation structure 1014, and an optical resonator structure 1021. The optical resonator structure 1021 may include a Fabry-Perot resonator, such as... Figure 11B This can be the optical resonator shown, and / or any other type discussed herein. The optical resonator structure 1021 may include a distal reflecting surface 1064 and a proximal reflecting surface 1063 arranged on either side of the optical cavity 1065. In an embodiment, the optical resonator structure 1021 is configured in a lateral configuration. In a lateral configuration, the acoustic response surface or surface of the optical resonator structure 1021 configured to receive and detect acoustic signals (in the optical resonator 362, this surface may be the distal reflecting surface 364 or the proximal reflecting surface) is arranged such that the acoustic response surface or surface is oriented in the same direction as the direction in which the sensor fiber 351 extends. The sensor fiber 351 and the acoustic response surface or surface may have an axis substantially perpendicular to the axis of the sensor fiber 1001. In other embodiments, the angle between the axis of the acoustic response surface or surface and the axis of the sensor fiber 1001 may be 0° depending on the desired angle of acoustic sensitivity. o and 90 o As discussed above, the optical resonator structure 1021 can be further configured to detect, measure, and / or respond to other physical parameters.

[0165] Figure 12 Embodiments of sensor optical fibers according to an invention are shown, providing the capability for acoustic detection from the direction behind the distal end of the sensor or the capability for near-side detection. Sensor optical fibers described herein, such as sensor fiber 301, sensor fiber 351, and sensor fiber 801, may be provided with improved near-side detection capability. Figure 12A sensor fiber 351 with an optical resonator structure 361 is shown, the optical resonator structure having a proximal reflecting surface 363 and a distal reflecting surface 364 arranged to share an axis with an optical waveguide 371. Both the proximal reflecting surface 363 and the distal reflecting surface 364 serve as acoustic response surfaces. To improve backsight capability, the cladding structure 353 may include a material selected to minimize acoustic impedance mismatch with the intended medium in which the sensor fiber 351 will be used. By minimizing the acoustic impedance mismatch, the critical angle of the boundary between the sensor fiber 351 and the medium in which it is housed increases, thereby enabling the optical resonator structure 361 to receive acoustic signals over a wider angular range. For example, the sensor fiber 351 intended for use in the human body may include a cladding structure 353 comprising a polymer selected to optimize detection sensitivity by minimizing any acoustic impedance mismatch. In an embodiment, the cladding structure 353 may be selected to have at least one of a Young's modulus (E) smaller than that of the core 352, a photoelastic coefficient greater than that of the core 352, and a refractive index (n) smaller than that of the core 352. In an embodiment, the cladding structure 353 may comprise benzocyclobutene (BCB) or polydimethylsiloxane (PDMS), each having a small Young's modulus (E), a high photoelastic coefficient, and a small refractive index (n). Reducing acoustic impedance mismatch can increase the acoustic signal passing through the cladding structure 353 and impacting the proximal reflecting surface 363. A smaller Young's modulus can increase the stress-dependent deformation of the cladding structure 353, thereby increasing the sensitivity to incident acoustic signals. A higher photoelastic coefficient can also produce greater sensitivity to acoustic signals because the optical properties of such materials exhibit larger strain-dependent changes. Other suitable materials for the cladding structure 353 may include ultrasonically enhanced materials, such as polyvinylidene fluoride, poly(p-xylene), polystyrene, etc.

[0166] Figure 13 Embodiments of sensor fibers providing improved rear-view acoustic detection capabilities according to embodiments of the present invention are shown. Sensor fibers described herein, such as sensor fiber 301, sensor fiber 351, and sensor fiber 801, can be provided with improved rear-view detection capabilities, such as... Figure 13 As shown. Figure 13A sensor fiber 1251 with an optical resonator structure 1261 is shown. The optical resonator structure 1261 includes an optical resonator defined by a near-side reflecting surface 363 and a far-side reflecting surface 364, both surfaces being arranged to share an axis with an optical waveguide 371 (e.g., the optical resonator is positioned in the same manner as the forward configuration described above). An optical cavity 365 is arranged between the near-side reflecting surface 363 and the far-side reflecting surface 364. Both the near-side reflecting surface 363 and the far-side reflecting surface 364 serve as acoustic response surfaces. The optical resonator structure 1261 may further include any features of the optical resonators and optical resonator structures discussed herein in any suitable combination. To increase backsight capability, the optical resonator structure 1261 may include a far-side portion of the optical waveguide 371, specifically configured to increase acoustic sensitivity at the near-side reflecting surface 363. The optical resonator structure 1261 may include a cladding structure at the distal end of the optical waveguide 371, which may include a proximal cladding structure portion 353A and a distal cladding structure portion 353B. The distal cladding structure portion 353B is positioned closer to the optical resonator. The distal cladding structure portion 353B may be selected to have a material that reduces or minimizes acoustic impedance mismatch with the intended medium in which the sensor fiber 1251 will be used. For example, the distal cladding structure 353B may comprise a polymer, as discussed above. In embodiments, the distal cladding structure 353B may comprise benzocyclobutene (BCB) or polydimethylsiloxane (PDMS), each of which has a small Young's modulus (E), a high photoelastic coefficient, and a small refractive index (n). The distal cladding structure 353B may have a length dimension sufficient to allow acoustic signals from various back-view angles to reach the proximal reflecting surface 363 of the optical resonator. The near-side cladding structure portion 353A may contain any suitable material for the optical waveguide, including, for example, silicon dioxide. As discussed above, the optical resonator structure 1261 may be further configured to detect, measure, and / or respond to other physical parameters.

[0167] Figure 14 The directional range of an optical resonator structure according to an embodiment of the present invention is shown. As discussed above, the optical resonator structure 1261 can be configured to detect acoustic signals over a wide incident range. In embodiments, the optical resonator structure 1261 can be configured to detect acoustic signals across a directional range of at least 180 degrees, at least 270 degrees, at least 300 degrees, or at least 330 degrees. In some embodiments, the optical resonator structure 1261 can be configured to detect acoustic signals omnidirectionally, for example, across a range of 360 degrees. Figure 14A side view of an optical resonator structure 361 according to an embodiment of the present invention is shown. A circle 1305 represents a 360° range around the optical resonator structure 1261 and has an axis 1306 substantially perpendicular to the axis 1307 of the optical resonator structure 1261. The circle 1305 represents a 360° range from which an acoustic signal can be incident on the optical resonator structure 1261. The optical resonator structure 1261 can be configured to detect acoustic signals in the acoustic response portion 1303 of the circle 1305, and can have reduced sensitivity or detection capability in portions containing acoustically reduced sensitivity, including the lateral portion 1301 and the core portion 1302. In the lateral portion 1301, the incident acoustic signal may be less detectable due to the oblique angle of incidence onto the reflecting surface of the optical resonator. In the core portion 1302, the acoustic signal may be less detectable due to obstruction from the core of the optical waveguide. The sum of the ranges of the acoustic response portions 1303 can represent the range from which the optical resonator structure 1261 detects acoustic signals. Different arrangements of optical resonator structures (e.g., lateral optical resonator structure 1021) can have different arrangements of acoustic response portion 1303 and acoustic sensitivity reduction portion.

[0168] In this embodiment, the optical resonator structure 361 is radially symmetrical. Therefore, the acoustic response range defined by the two-dimensional circle 1305 can be rotated about axis 1307 to define a three-dimensional acoustic response range for the optical resonator structure 1261. It should be understood that further effects on the acoustic response range can be caused by structures surrounding the optical resonator structure 1261, including, for example, the distal end 231 of a medical device.

[0169] Figure 15An optical resonator structure comprising an in-fiber Bragg grating is illustrated according to an embodiment of the present invention. Optical resonator structure 1421, as well as any sensor fiber discussed herein, can be provided. Optical resonator structure 1421 includes a distal reflective surface 1464, an elongated optical cavity 1465 comprising a distal cladding structure 1453A and a proximal cladding structure 1453B, and a Bragg grating 1470. As in optical resonator structure 1261, distal cladding structure 1453A may comprise a polymer (e.g., benzocyclobutene (BCB) or polydimethylsiloxane (PDMS)), while proximal cladding structure 1453B may comprise, for example, silica glass. The length of proximal cladding structure 1453B may be greater than that of distal cladding structure 1453A, for example, exceeding 2x, exceeding 5x, exceeding 10x, etc. In an embodiment, the proximal cladding structure 1453B can be approximately 10 times the length of the distal cladding structure 1453A. For example, the length of the distal cladding structure can be approximately 10 micrometers, while the length of the proximal cladding structure is approximately 100 micrometers. In an embodiment, the proximal cladding structure 1453B can have a Young's modulus in the range of 60-80 GPa, while the distal cladding structure 1453A has a Young's modulus in the range of 0.8-1.2 GPa. In an embodiment, the proximal cladding structure 1453B can have a photoelastic modulus C1 = -6*10⁻⁶. -13 1 / Pa and C2 = -4.2 * 10 -12 1 / Pa, while the distal cladding structure 1453A has a photoelastic coefficient C1 = -4.8 * 10. -11 1 / Pa and C2 = -2.9 * 10 -111 / Pa. While these figures are provided, such photoelastic coefficients are relative figures depending on the chosen material. For the distal end, materials with larger C1 or C2 values ​​are preferred to optimize acoustic sensitivity. The Bragg grating 1470 is integrated within the structure of core 1412 and defines a change in the refractive index of core 1412, thereby creating a structure capable of reflecting light of a specific wavelength. The optical resonator structure 1421 operates as a hybrid Fabry-Perot resonator. In this configuration, the distal cladding structure 1453A (e.g., a polymer structure) provides the dominant response to the acoustic signal. The distal cladding structure 1453A can be directly fabricated on top of an optical fiber with an in-fiber Bragg grating reflector via two-photon polymerization (TPP) 3D printing. One advantage of the hybrid optical resonator structure 1421 is the combination of wide bandwidth and high sensitivity. In some designs, there is a trade-off between wide bandwidth and high sensitivity. In this hybrid configuration, the elongated optical cavity 1465 has a relatively long total length because it is the sum of the distal cladding structure 1453A and the proximal cladding structure 1453B. For a longer cavity length, the frequency bandwidth response might be narrower in a conventional design. However, in this hybrid configuration, since the primary response of the FPI sensor originates from the polymer region, the effective sensor thickness remains very small, and a broadband response is provided. As discussed above, the optical resonator structure 1421 can be further configured to detect, measure, and / or respond to other physical parameters.

[0170] Figure 16 The steps of a method for generating position and imaging information using a fiber-optic optical sensor are illustrated. Further details can be found in U.S. Provisional Application No. 63 / 522,994, filed June 23, 2023, entitled "Transponder Tracking and Ultrasound Image Enhancement," and in parallel U.S. Patent Application No. 109835-1394978, filed October 23, 2023, entitled "Transponder Tracking and Ultrasound Image Enhancement."

[0171] Method 2000 may include box 2010, in which a transponder, for example Figure 2 The acoustic probe 245 shown transmits acoustic pulses into the medium. The transponder can transmit these pulses using various known methods or as described above.

[0172] At frame 2020, fiber optic sensor 101 receives ultrasound pulses and / or scattered signals or tissue harmonics transmitted from probe 245. The fiber optic sensor 101 then converts the ultrasound pulses, scattered signals, and / or tissue harmonics into signals that are subsequently transmitted to processing unit 209.

[0173] At block 2030, processing unit 209 determines the position of the fiber optic sensor at least in part based on signals received from probe 245. For example, processing unit 209 may utilize triangulation or coherent image formation to determine the position of the distal end of the medical device based on multiple signals received from probe 245 and fiber optic sensor 101.

[0174] At box 2040, processing unit 209 and image reconstruction or data unit 206 generate an ultrasound image based on the signal returned to probe 245 and / or the scattered signal and tissue harmonics sensed by the fiber optic sensor. The ultrasound image can be transmitted to a display and displayed thereon.

[0175] At block 2050, the processing system modifies the ultrasound image based on ultrasound pulses received from fiber optic sensor 101. In an embodiment, the processing system may also generate and display ultrasound images based on ultrasound pulses received by the fiber optic sensor, without requiring information from ultrasound pulses received by probe 245.

[0176] At frame 2060, the processing system 200 overlays the position of the fiber optic sensor 101 onto the ultrasound image. Therefore, when viewed by a user, such as an ultrasound technician, physician, other medical professional, or patient, the fiber optic sensor 101 at the distal end of the medical device is displayed on the same screen as the ultrasound image, indicating the position of the fiber optic sensor 101 at the distal end of the medical device within the medium.

[0177] Figure 17 A and 17B illustrate a needle configured with sensor fibers according to embodiments herein. Needle 1500A may be an example of a distal end 231 of a medical device and may include one or more sensor fibers 1501 integrated therewith. Sensor fibers 1501 may include any of the sensor fibers described herein (having any of the optical resonator structures), and / or may include any combination of features of the sensor fibers described herein. Needle 1500A may be any type of needle having any suitable size or function. Needle 1500A includes a needle body 1505 having a needle shaft portion 1510 and a needle tip portion 1511. The needle tip portion 1511 may be characterized by a needle polishing angle 1523. Furthermore, needle 1500A includes at least one sensor channel 1512 extending over the needle body 1505 to at least a portion of the length of the needle shaft portion 1510 and the needle tip portion 1511.

[0178] In an embodiment, sensor channel 1512 may include grooves, recesses, or recesses in needle body 1505. Sensor channel 1512 may be sized and configured to receive sensor fiber 1501 according to an embodiment of the invention. For example, in an embodiment, the width of sensor channel 1512 may be approximately 125 to 250 micrometers to accommodate sensor fiber 1501 with a diameter of 80 micrometers. Needle 1500A may include a plurality of sensor channels 1512 to accommodate a plurality of sensor fibers 1501. For example, needle 1500A may include two, three, four, or more sensor channels 1512 for accommodating a plurality of sensor fibers 1501 arranged around the perimeter of needle 1500A. Sensor fibers 1501 are arranged within sensor channels 1512 such that the distal end of the load optical resonator structure is positioned at or near the distal end. Sensor channel 1512 may be configured with a depth such that sensor fiber 1501 does not extend beyond the outer surface of needle body 1505.

[0179] In other embodiments, the sensor channel can be created by adding material to the outer surface to form a channel, for example, as a guide. In one example, the material can be laminated on the outside of the needle to form a channel 1512 as a continuous or intermittent structure of protrusions. In another example, an adhesive material or tape can be wrapped in a spiral configuration, with space within the spiral to form the sensor channel, or it can be selectively positioned along the length of the needle to form the sensor channel and guide the sensor fiber along the length. In yet another example, the extrusion needle can include a tubular sensor channel in the form of an extended lumen through which it passes.

[0180] Sensor channel 1512 allows sensor fiber 1501 to be located within a protected area of ​​needle body 1505. This serves to protect sensor fiber 1501 and create a smooth needle surface for insertion. Sensor channel 1512 can be positioned on the outer surface of needle body 1505 (e.g., Figure 17 (as shown in B) or placed on the inner surface of the needle body 1505.

[0181] The sensor fiber 1501 can be secured to the needle body 1505. In an embodiment, the sensor fiber 1501 can be secured within the sensor channel 1512 using a potting compound, such as Norland-65 adhesive, Norland 81 adhesive, MY-132A polymer, MY-133, BIO-133, DC-133, or any other suitable potting compound. The potting compound can be selected based on its acoustic and mechanical properties, such as sound velocity, acoustic impedance, thermal conductivity, water resistance, etc. In addition to mechanically securing and protecting the sensor, the potting compound can also provide modification for acoustic impedance matching with the surrounding medium. The potting compound can be used on all or part of the sensor channel 1512. In an embodiment, the sensor fiber 1501 can be secured within the sensor channel 1512 using a sheath 1520. The sheath 1520 is configured to enclose the needle body 1505. The sheath 1520 can mechanically secure the sensor fiber 1501 to the needle body 1505. The sheath can enclose the needle, with the optical fiber within a groove, allowing the fiber to float freely within the groove / slot. This allows the needle to bend / be flexible. In an embodiment, the sensor optical fiber 1501 can be at least partially secured by both the sheath 1520 and the potting compound. This arrangement allows relative movement between the sensor optical fiber 1501 and the needle body 1505, thereby providing potential strain relief in the event of needle bending. The needle 1500A can be made of any suitable material, including, for example, medical-grade materials, including metals such as stainless steel or polymers such as PEEK (polyetherketone). In an embodiment, the needle 1500 can be manufactured using additive manufacturing techniques, such as 3D printing, injection molding, or extrusion.

[0182] Figures 18A and 18B show another embodiment of a needle with an optical fiber-based sensor. The needle 1500B may further include one or more windows 1513. Window 1513 is an opening in the needle body 1505 located at the end of a sensor channel 1512. The needle 1500B may include multiple sensor channels 1512 and corresponding multiple windows 1513 to accommodate multiple sensor optical fibers 1501. The sensor optical fibers 1501 may be arranged within the sensor channels 1512 such that the distal end carrying the optical sensor extends into the window 1513. In this embodiment, the distal end of the sensor optical fiber 1501 may be secured within the window 1513 by a potting compound, while the proximal portion of the sensor optical fiber 1501 may be secured to the needle body 1505 by a sheath 1520. This allows relative movement between the sensor optical fiber 1501 and the needle body, thereby providing strain relief in the event of needle bending.

[0183] Window 1513 allows acoustic signals to reach the fiber optic sensor 1501 without being blocked by the needle body 1505. The edges of window 1513 can create boundaries for acoustic signal diffraction and allow the acoustic signal to bend and propagate around the window edges to reach the fiber optic sensor at the end of the sensor fiber optic 1501. The diffraction effect has the following function: increasing the circular range of acoustic signal detection by the sensor fiber optic 1501. In addition, the edges of the channels on the needle surface can also have a diffraction effect that helps detect the needle axis.

[0184] In embodiments, the optical ultrasound sensor according to an embodiment of the present invention can be integrated with a medical device (e.g., at the distal end 231 of the medical device) and can work with an ultrasound source (array) configured in an off-body location to provide positional information of the distal end 231 of the medical device and / or provide real-time acoustic monitoring of the target / anatomical region during surgery. In different application scenarios, the direction of the incoming acoustic signal can be broadly classified into two categories: (1) lateral emission; and (2) axial emission, such as... Figure 18C and 18D As shown.

[0185] Figure 18C and 18D The acoustic signal incident on the sensor fiber optic cable positioned within the needle window 1513 is shown. For clarity, the sensor fiber optic cable is not shown in these figures. Figure 18C The transverse acoustic signal is shown as 1600, while... Figure 18D The axial acoustic signal is shown.

[0186] Figure 18C The transverse acoustic signal 1600 is typical when using a side-view endoscope ultrasound transducer or an external transducer. The position of the window 1513 near the needle tip 1511 allows the ultrasonic field to reach the window (and the fiber optic end sensor structure located therein) from either side without being blocked by the opposing wall of the needle. The fiber optic end sensor structure itself can be arranged laterally or forward and can also be a polarization-based sensor configured to receive lateral (transverse) signals, depending on the application requirements.

[0187] Figure 18D The axial acoustic signal 1601 is typical for a front-view endoscopic ultrasound transducer. Due to the small space occupied by the endoscopic unit, the typical angle of incidence relative to the needle may be small. Figure 18D As shown, when the incident angle is less than the needle polishing angle 1523 (e.g. Figure 18DAs shown, at least a portion of the acoustic signal 1601 can be blocked by the needle body (shown as thicker crosshairs). To address this issue, in one embodiment, an additional window 1513 opposite the sensor window can be included in the needle body 1505 to allow the axial acoustic signal 1601 to pass through and reach the optical resonator structure. In another embodiment, the orientation of the needles 1500A / B can be manipulated to ensure that low-angle axial acoustic signals arrive from the portion of the needle not positioned by the optical resonator structure. In another embodiment, the polishing angle 1523 can be selected based on the desired acoustic incident angle.

[0188] exist Figure 19 Another embodiment of a needle with an optical fiber-based sensor is shown. Similar to needles 1500A and 1500B, needle 1500C includes a needle body 1505 having a needle shaft portion 1510 and a needle tip portion 1511. The needle tip portion 1511 may be characterized by a needle polishing angle. Furthermore, needle 1500C includes at least one sensor channel 1512 extending from the needle body 1505 to at least a portion of the length of the needle shaft portion 1510 and the needle tip portion 1511. Needle 1500C may include one or more sensor optical fibers 1501C disposed in one or more of its sensor channels 1512. Sensor optical fiber 1501C may be similar to sensor optical fiber 301C, and therefore may include an optical fiber end sensor structure 1521 disposed at its end and one or more polarization-based sensor structures 1522 disposed along its length. A polarization-based sensor structure 1522, positioned along the length of the needle 1500C, can provide enhanced visualization of the needle 1500C when an acoustic signal impacts the needle 1500C. Information collected from an optical signal indicating the incident acoustic signal can be used alone and / or in combination with conventional acoustic ultrasound imaging to provide improved visualization of the needle 1500C. The polarization-based sensor structure 1522 can be described above in relation to the polarization-based sensor structure 322C and the polarization-based sensor structure 322C. Figure 6D and 6DD Operate according to the principles discussed.

[0189] Figure 20A and Figure 20B Another close-up view of the needle 1500 with integrated sensor fiber optic 1501 is provided. Figure 20A A perspective view is shown from the first side of the needle 1500 where channel 1512 is located, and Figure 20BA perspective view of the needle 1500 from a second side opposite to the first side is shown. The second side of the needle 1500 includes an internal view of the needle 1500 at the needle tip portion 1511. As shown, a sensor fiber 1501 is disposed within a sensor channel 1512 of the needle 1500, extending from the needle shaft portion 1510 and entering the needle tip portion 1511. A window 1513 is disposed within the needle tip portion 1511, thereby ensuring that both sides of the window 1513 (and the sensor fiber 1501 disposed therein) are exposed to incoming acoustic signals. Furthermore, Figures 20A-20B The encapsulation compound 1525 is shown to fix the sensor optical fiber 1501 within the window 1513.

[0190] exist Figure 20C In another embodiment shown, the sensor fiber 1501D can be fixed to the surface of the needle body 1505D of the needle 1500D that does not have a channel or other fiber receiving structure. The fiber 1501D can be fixed to the needle 1500D using a suitable polymer or compound 1527 selected according to its acoustic and mechanical properties. A suitable polymer or compound 1527 can be selected based on its acoustic and mechanical properties, such as sound velocity, acoustic impedance, thermal conductivity, water resistance, etc. In addition to mechanical fixation and protection of the sensor on its surface, a suitable polymer or compound 1527 can also provide modification for acoustic impedance matching with the surrounding medium. Similarly, as Figure 20D As shown, a sheath 1520D can be used to secure the sensor fiber to the needle body 1505D. The sheath 1520D is configured to enclose the needle body 1505D. The sheath 1520D can mechanically secure the sensor fiber 1501D to the needle body 1505D. The sheath can enclose the needle in a manner that allows the fiber to move within the sheath. This allows the needle to bend / be flexible. In an embodiment, the sensor fiber 1501D can be secured at least partially by both the sheath 1520D and the polymer or compound 1527. Such an arrangement can allow relative movement between the sensor fiber 1501D and the needle body 1505D, thereby providing potential strain relief in the event of needle bending. This embodiment can be further included with a window in other embodiments and in a windowed manner. The fiber located within the window can be further secured using a potting compound or polymer in the manner of the previous embodiments.

[0191] Figure 21A distal end of a medical device with fiber optic end sensors is shown according to an embodiment of the invention. The distal end 1901 of the medical device includes a catheter 1902 and a medical instrument, such as a needle 1903. The catheter 1902 is configured to deliver the needle 1903 (e.g., providing access to a lumen through which the needle can be delivered) to a treatment and / or diagnostic site via a lumen 1904. The catheter 1902 may further include a guidewire lumen 1905 configured to guide the catheter 1902 to the treatment and / or diagnostic site along the guidewire. The needle 1903 is configured to extend from the lumen 1904 of the catheter 1902 upon reaching the treatment and / or diagnostic site (e.g., by an operator, human, or robot). In an embodiment, the needle 1903 may be configured similarly to the needle 1500, including one or more sensor fibers 1501 disposed thereon or integrated therewith. In an embodiment, the catheter 1902 may include one or more sensor fibers and one or more acoustic transducers disposed thereon or integrated therewith. In an embodiment, one or more sensor fibers 1501 may be used to sense, monitor, and / or track the position of the needle 1903 (e.g., based on acoustic signals generated by an acoustic transducer / probe located outside the medium in which the conduit 1902 is used). One or more sensor fibers 1501 and one or more acoustic transducers disposed on the conduit 1902 may be used to generate images, such as the detection of acoustic echoes via the one or more sensor fibers. The one or more acoustic transducers may generate acoustic signals, while the one or more sensor fibers receive echoes or reflections of these signals based on their interaction with the surrounding medium. The acoustic transducers will also receive reflected or scattered acoustic signals and / or tissue harmonics, which may then be used to create an image of the surrounding area to which tracking information will be added.

[0192] Figure 22 This illustrates an example use of a fiber-optic optical sensor incorporated into a needle. The illustrated use can incorporate needles 1500A, 1500B, 1500C, 1500D, or any suitable needle with a fiber-optic optical sensor. Figure 22 As shown, an external acoustic probe 2245 with a needle 1500A / B / C / D and a fiber-optic optical sensor can be used. As discussed herein, in positioning / guiding embodiments, the fiber-optic optical sensor can receive acoustic signals generated by the external acoustic probe 2245. These acoustic signals can then be used alone or in combination with reflected acoustic signals captured by the acoustic probe to determine the position of the needle within the medium 2260 (e.g., the patient's body).

[0193] Figures 23A-23BAn embodiment of a fiber-optic optical sensor incorporated into a catheter-delivered needle is illustrated. For example, the catheter-delivered needle can be used in a biopsy procedure. Needle 2515 can be delivered to the surgical site via catheter 2503. Needle 2515 may incorporate a fiber-optic optical sensor 2501, as described in the various embodiments herein. After delivery to the surgical site via catheter 2503, needle 2515 can extend from the lumen in catheter 2503 to perform the procedure. Needle 2515 can be monitored, guided, and / or positioned using one or more external acoustic transducers that provide acoustic signals received by the fiber-optic optical sensor 2501. For example, the acoustic transducer can be associated with an optical sensor system. Optical sensor systems, which may be examples of the various optical sensor systems described herein, can provide the processing and signal generation / reception requirements necessary to perform the photoacoustic signal sensing methods described herein. In other embodiments, such as... Figure 23B As shown, conduit 2503 may include one or more additional transducers. For example, the conduit may include a hybrid sensor array 2547, which includes one or more of an AEG (or other suitable acoustic transducer array) array 2548 and a photonic integrated circuit (PIC) optical sensor array 2549. In embodiments, the hybrid sensor array 2547 may include any suitable fiber optic sensors discussed herein, such as fiber optic end sensors and polarization-based sensors, as a complement to or alternative to the PIC optical sensor array 2549. In the embodiments, US Application Publication No. 20230148869, filed November 18, 2022, entitled "Mixed Ultrasound Transducer Arrays" and incorporated herein by reference; US Application Publication No. 20220350022, filed April 29, 2021, entitled "Modularized Acoustic Probe" and incorporated herein by reference; and US Application No. 63 / 550,515, filed February 6, 2024, and incorporated herein by reference, disclose various optical sensors that can be used in the mixed transducer array. The PIC array 2549 can be used to detect acoustic signals. Similar to the fiber optic end sensors discussed herein, the PIC array 2549 can be used to detect acoustic signals by measuring or detecting changes in the optical properties of the PIC array 2549 caused by the incidence of an acoustic signal. In an embodiment, acoustic signal data captured in different ways by fiber-based optical sensors 2501, PIC array 2549, AEG array 2548 and external acoustic transducers can be provided by the optical sensor system in any combination form for monitoring, guiding and positioning needle 2515 (and catheter 2503 for delivering the needle) and generating images of the medium in which catheter 2503 is deployed (e.g., surgical site).

[0194] In other embodiments, the fiber-optic optical sensors according to the embodiments herein can be used for a variety of additional purposes. For example, fiber-optic optical sensors can be used to track a cannula configured with an optical camera and a movable ultrasound transducer for use in vivo during minimally invasive surgery. In another embodiment, a transcutaneous or percutaneous ultrasound probe may be configured with one or more fiber-optic optical sensors according to embodiments of the invention. In another embodiment, a guidewire may be configured with one or more fiber-optic optical sensors according to embodiments of the invention. In another embodiment, a probe may be configured with one or more fiber-optic optical sensors.

[0195] Examples of hybrid sensor arrays in Figures 24A to 40 Presented herein. Generally, hybrid sensor arrays (e.g., comprising both AEG elements and fiber optic sensors) can be incorporated into hybrid sensor transducers usable in any suitable ultrasound environment, including at least handheld probes, intravascular ultrasound (IVUS), endovascular ultrasound, endovascular ultrasound (EUS), endobronchial ultrasound (EBUS), intraoperative ultrasound (IOUS), endoscopic ultrasound, robotic ultrasound probes, etc. As discussed herein, hybrid sensor arrays can operate by employing AEG elements to generate acoustic signals (e.g., ultrasound) and employing both AEG elements and fiber optic sensors to receive reflected acoustic signals. In some embodiments, the AEG elements are optimized for acoustic signal transmission and may or may not be used for receiving acoustic signals. The hybrid sensor arrays described herein may further include fiber optic sensors configured to measure, sense, and / or detect physical parameters. In additional embodiments, the hybrid sensor arrays described herein may include fiber optic sensors with different physical parameter sensitivities, as discussed above, to improve physical parameter measurement. A processing system associated with these hybrid sensor arrays can then be used to interpret the received acoustic signals and provide ultrasound images and / or data related to the sensed physical parameters. Figures 24A to 40 The dimensions and shape of the probes shown are provided as examples only. For example, Figure 26A and 26B A hybrid sensor transducer probe 2500 suitable for in vitro or ex vivo use is shown. In alternative uses, such as intravascular ultrasound (IVUS), endovascular ultrasound, endovascular ultrasound (EUS), endobronchial ultrasound (EBUS), intraoperative ultrasound (IOUS), endoscopic ultrasound, etc., and the hybrid sensor transducer probes of various embodiments discussed herein may be configured with appropriate external dimensions (e.g., having a small hybrid sensor array and configured for deployment via catheters, guidewires, endoscopes, or another device intended for in vivo or live use).

[0196] Generally, in embodiments, a hybrid sensor array device for imaging a target 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, different from the first type. The first type may be a transducer (e.g., AEG material, including, for example, piezoelectric materials such as lead zirconate titanate (PZT), ceramics, piezoelectric single crystals (e.g., PIN-PT, PIN-PMN-PT), polymer thick film (PTF), polyvinylidene fluoride (PVDF), capacitive micromechanical ultrasonic transducer (CMUT), piezoelectric micromechanical ultrasonic transducer (PMUT), and many other materials configured to transmit sound waves), and the second type may be any optical sensor described herein (e.g., interference-based optical sensors such as optical resonators, optical interferometers, etc.) for detecting acoustic signals (e.g., echoes or reflections) corresponding to the transmitted sound waves. In some embodiments, the array elements of the first and second types are configured to detect acoustic signals. In embodiments, the array elements of the first type are configured to transmit and detect acoustic signals, and the array elements of the second type are configured to detect acoustic signals. In one embodiment, the hybrid ultrasound imaging probe includes an AEG material subarray and a fiber optic sensor array, which may comprise, for example, a photonic integrated circuit (PIC) receiver subarray or a structured collection of individual fiber optic sensors (each of which may be referred to as an optical subarray), as discussed below. In another embodiment, the hybrid ultrasound imaging probe may comprise the hybrid sensor array discussed herein, encapsulated and incorporated within a suitable housing.

[0197] Generally, hybrid sensor arrays can receive ultrasound with wider bandwidth and larger incident angles, thus improving upon conventional transducers using only AEG. As discussed herein, fiber optic sensors can be configured to receive wider bandwidths of reflected acoustic signals, such as signals generated by tissue harmonics (e.g., returned acoustic signals that are integer multiples of the transmitted acoustic frequency), potentially achieving higher tissue imaging resolution. The ability to receive wider bandwidth signals can improve axial resolution because using higher frequency signals (e.g., tissue harmonics) results in shorter pulse lengths. For example, a 5 MHz acoustic signal can induce tissue harmonics of 10 MHz, 15 MHz, 20 MHz, 25 MHz, or higher. An AEG transducer optimized for transmission at a specific frequency (e.g., 5 MHz) may not be suitable for receiving signals at other frequencies (10 MHz, 15 MHz, 20 MHz, 25 MHz). Using an AEG transducer in transmission-only mode allows the AEG transducer to be optimized for transmission at a first frequency, while the photoacoustic sensor according to embodiments herein is optimized for reception at higher frequencies with high bandwidths induced by tissue harmonics.

[0198] Furthermore, as discussed in this paper, fiber optic sensors can have a wider receiving angle, which can further provide imaging advantages. For example, a wider receiving angle can improve lateral resolution because a larger aperture can improve diffraction limit. In addition, this wider receiving angle is beneficial for Doppler imaging techniques and can expand the available angle range for beam steering. Moreover, as discussed in this paper, due to the small size of the acousto-optic transducer discussed herein, a larger receiving angle can be achieved without a very large array (which AEG receiver arrays might require).

[0199] Hybrid sensor arrays can further improve and / or modify the transducer housing, enabling better integration with transducers using only AEG. For example, because the photoacoustic sensors discussed in this paper are insensitive to electromagnetic interference (EMI), the transducer housing can be made thinner, lighter, and cheaper, since only AEG transducer assemblies require EMI shielding. The EMI suppression / cancellation achievable using photoacoustic sensors also contributes to improved performance of photoacoustic-based receiving transducers.

[0200] Other benefits of hybrid sensor arrays, achieved by using one type of sensor array (e.g., an AEG array) for transmission and a second type of sensor array (e.g., an acousto-optic sensor) for reception, can be realized by optimizing the positioning of the individual transmission and reception transducers. Imaging can be improved by changing the relative positions between the individual transducers. For example, separating the transmission and reception transducers can reduce edge diffraction (side lobes).

[0201] Furthermore, hybrid sensor arrays can provide the benefits of multidimensional sensing offered by the incorporated fiber optic sensors. As discussed above, fiber optic sensors can be configured to measure, detect, and / or sense physical parameters beyond acoustic signals. Incorporating such fiber optic sensors into a hybrid sensor array allows the same sensors to detect and / or measure additional physical parameters, thus providing greater flexibility in the use of hybrid sensor array probes. In embodiments, regarding Figure 24A-35 Each hybrid sensor array described in C and 39A-39C can be further configured with multidimensional sensing capabilities, including the use of sensor fibers with different physical sensitivities. Additionally, regarding... Figures 36-38 and Figure 40 Each system described may include a processing system configured to interpret optical signals from a hybrid sensor array to measure other physical parameters in addition to acoustic signals.

[0202] Figure 24A and 24B A hybrid sensor probe and a hybrid sensor array according to embodiments herein are illustrated. In the embodiments, such as Figure 24AAs shown, the hybrid sensor probe 2401 comprises an array of one or more AEG elements 2403 arranged circumferentially around the fiber optic sensor 2402. The fiber optic sensor 2402 may comprise any fiber optic sensor discussed herein (e.g., a fiber optic end sensor). The hybrid sensor probe 2401 can be used in conjunction with any suitable photoacoustic sensor system described herein (e.g., system 200). In other embodiments, such as Figure 24B As shown, the hybrid sensor probe 2450 may include a hybrid sensor array 2411, which may include an array of multiple fiber optic sensors and one or more AEG elements.

[0203] Figure 24C and 24D Additional embodiments of the hybrid sensor array transducer are shown. Hybrid sensor array transducers 3000 and 3100 are arrays of multiple fiber optic sensors 3071 arranged in a transducer head. The fiber optic sensors 3071 can be any fiber optic sensor described herein, and more specifically, can be fiber optic end sensors conforming to embodiments herein. Hybrid sensor array transducers 3000 and 3100 may each further include an AEG element to generate an acoustic signal. Hybrid sensor array transducer 3000 includes a fiber optic sensor substrate 3002 to capture the fiber optic sensors 3071 and multiple AEG elements 3003. The fiber optic sensor substrate 3002 may include structures configured to hold the fiber optic sensors 3071. The probe containing the hybrid sensor array transducer 3000 may further include suitable structures and materials to form an interface layer that may further include a matching layer, a coupling agent, and an acoustic lens. The fiber optic sensor array transducer 3000 is a linear structure and forms a linear sensor array. The fiber optic sensor substrate 3102 is similar to the transducer head substrate 3002 and may contain the same elements. The fiber optic sensor substrate 3102 is curved, providing a curved array, and is incorporated into the hybrid sensor array transducer 3100. The AEG elements of the hybrid sensor array transducer 3000 are not shown.

[0204] Any of the hybrid sensor array transducers described herein can be linear or curved. Curved arrays offer the benefits of a wider field of view and better contact for probes with such arrays. Linear arrays offer benefits related to ease of fabrication. Furthermore, the wide field of view of the fiber optic sensors described herein can at least partially compensate for the narrower field of view associated with linear structures.

[0205] Figure 25A , 25BFigures 25C, 25D, and 25E illustrate additional embodiments of hybrid sensor arrays according to the embodiments herein. These hybrid sensor array embodiments can be configured to include the fiber optic end sensors discussed herein and / or any other fiber optic sensors discussed herein. Figures 25A-25E Each of the diagrams illustrates a facet of a hybrid sensor transducer array, such as a facet from which acoustic energy is emitted and received. Although the faces of the hybrid sensor transducer array are shown as circular and rectangular, suitable variations of these shapes may be used without departing from the scope of the invention. The hybrid sensor arrays disclosed herein are not drawn to scale. Because the fiber optic sensors disclosed herein may be ten to twenty times or more smaller than AEG elements (e.g., a linear dimension of 125 micrometers versus 3 millimeters), the associated arrays may also be smaller. The arrays shown and described herein may contain any suitable number of sensors and may contain sensors arranged in more than one row, one column, one row, etc. As described herein, a “linear” array does not necessarily refer to a single row of sensors, but generally indicates that the overall shape of the array extends further in the first dimension than in the second dimension. The number of sensors and their spacing (e.g., pitch) in the following sensor arrays may vary depending on the application. In the examples, the pitch may be chosen to be approximately one-quarter or one-half of the expected incident acoustic wavelength.

[0206] Figure 25A A concentric hybrid sensor array 2550 is shown. Multiple fiber optic sensors can be arranged in a ring shape to form a fiber optic sensor array 2551. Multiple AEG elements can be arranged concentrically in a ring shape around the fiber optic sensor array 2551 to form an AEG element array 2552. In an embodiment, the positioning of the fiber optic sensor array 2551 relative to the AEG element array 2552 can be reversed. Compared to the linear arrays discussed herein, the concentric hybrid sensor array 2550 can provide an array occupying a smaller area.

[0207] Figure 25B A linear hybrid sensor array 2560 is shown. Multiple fiber optic sensors can be arranged linearly along the long dimension of the hybrid sensor array 2560 to form a fiber optic sensor array 2561. Multiple AEG elements can be arranged linearly, substantially parallel to the fiber optic sensor array 2561 (e.g., with a parallelism deviation within 10%), to form an AEG element array 2562. In this embodiment, a single fiber optic sensor array 2561 and a single AEG element array 2562 can be provided. The linear hybrid sensor array 2560 makes the array easy to manufacture.

[0208] Figure 25CA linear hybrid sensor array 2570 is shown. Multiple fiber optic sensors can be linearly arranged to form two fiber optic sensor arrays 2571, substantially parallel to each other along the long dimension of the hybrid sensor array 2570. Multiple AEG elements can be linearly arranged substantially parallel to the fiber optic sensor arrays 2571 to form an AEG element array 2572. The linear hybrid sensor array 2570 can enable the array to have an increased field of view and “1.5D” imaging. 1.5D imaging provides additional imaging information in the elevation dimension (e.g., a wider elevation aperture) by using two different fiber optic sensor arrays 2571, staggered from each other in the elevation dimension of the sensor arrays.

[0209] Figure 25D A linear hybrid sensor array 2580 is shown. Multiple fiber optic sensors can be linearly arranged to form a fiber optic sensor array 2581, substantially parallel to each other along the short dimension of the hybrid sensor array 2580. Multiple AEG elements can be linearly arranged substantially perpendicular to the fiber optic sensor array 2581 (e.g., with parallelism deviation within 10%) to form an AEG element array 2582. The linear hybrid sensor array 2580 can enable the array to have an increased field of view and “1.5D” imaging. 1.5D imaging provides additional imaging information in the elevation dimension (e.g., a wider elevation aperture) by using the fiber optic sensor array 2581, which extends in the elevation dimension of the sensor array.

[0210] In some embodiments, the hybrid sensor array may include fiber optic sensor arrays 2571 and 2581 to form a “box-shaped” fiber optic sensor array, thereby increasing the field of view in multiple dimensions.

[0211] Figure 25EAn example of a structure for incorporating a fiber optic sensor within a fixed array into a hybrid sensor array is shown. The structure of the hybrid sensor array 2590 can be configured or adapted for incorporation into any hybrid sensor array discussed herein. The hybrid sensor array 2590 may include a substrate 2591 having a first portion 2592 and a second portion 2593. The substrate 2591 may comprise a polymer or any suitable material. The sensor may comprise silicon dioxide or germanium-doped chalcogenide. The substrate 2591 may comprise rigid plastic, acrylic, glass, or silicon. Preferably, a rigid and heat-insensitive material may be selected. The second portion 2593 may be configured with one or more fiber optic sensor receiving portions 2595, which may be grooves, channels, notches, trenches, recesses, openings, or holes, etc., for providing a space in the second portion 2593 for arranging fiber optic sensors 2596. Epoxy resin, resin, or other adhesives 2594 may be deposited around the fiber optic sensors 2596 arranged in the receiving portion 2595. The adhesive 2594 may comprise, for example, but not limited to, a polymeric epoxy resin having low shrinkage and optical-grade qualities (e.g., transparency). The first portion 2592 can serve as a "cap" to complete the capture of the fiber optic sensor 2596. In embodiments, the first portion 2592 is not required, and the fiber optic sensor 2596 can be secured solely using the adhesive 2594. In embodiments, the adhesive 2594 is not required, and the fiber optic sensor 2596 can be secured solely via the mechanical clamping of the cap 2592. The substrate 2591 is used to capture the fiber optic sensor 2596 and maintain proper positioning and distance among them when used in a hybrid sensor array.

[0212] Figure 26A and 26B A hybrid sensor transducer probe 2500 is shown. The hybrid sensor transducer probe 2500 is suitable for in vitro use and may contain any of the hybrid sensor arrays and associated components described herein. The hybrid sensor transducer probe 2500 may contain two components: a photoacoustic transducer 2510 and an AEG-based transducer 2520. These two components are shown as separate parts here for discussion. It should be understood that the characteristics of these two components can be co-doped according to functional requirements, as discussed in more detail below.

[0213] The photoacoustic transducer 2510 may include a fiber optic sensor array 2521 (which may be any fiber optic sensor array disclosed herein), containing one or more fiber optic sensors conforming to embodiments herein and housed within a probe 2507 of a hybrid sensor transducer probe 2500. The photoacoustic transducer 2510 may further include an optical waveguide 2502 (e.g., fiber optic cable) disposed within a handle 2506 of the hybrid sensor transducer. The optical sensor array 2521 and the optical waveguide 2502 may be optically coupled to a light source using optical sensor circuitry, such as the optical sensor circuitry disclosed in U.S. Application No. 18 / 429,517, filed February 1, 2024, and incorporated herein by reference, entitled "Optical Sensor Circuit and Optical Sensing Method." Such an arrangement would further require components for directing light to and from various sensors on the array, such as fan-out couplers on the probe. The AEG-based transducer 2520 may include an AEG transducer stack 2511 comprising one or more AEG transducers and components required for their operation, housed within the probe 2507 of the hybrid sensor transducer probe 2500. The AEG-based transducer 2520 may further include circuitry 2512 such as flexible circuitry, interconnects 2513, and connecting cables 2514 (e.g., coaxial cables, etc.). These may be housed as needed within the handle 2506 and / or probe 2507 of the hybrid sensor transducer probe 2500. The hybrid sensor transducer probe 2500 may further include a hybrid cable 2573 configured to carry the optical waveguide 2502 and connecting cable 2514 back to the system.

[0214] In one embodiment, the fiber optic sensor array 2521 may comprise a bundle of fiber optic sensors, as disclosed herein. In other embodiments, the fiber optic sensor array 2521 may comprise an on-chip fiber optic sensor array 2600, such as... Figure 27A As shown in the image. Figure 27AAn on-chip fiber optic sensor array 2600 is shown, which may comprise an array of fiber optic sensors formed together on a single chip. In an embodiment, the on-chip fiber optic sensor array 2600 may include multiple optical waveguides 2601 (e.g., fiber cores) sharing a distal reflective surface 2603 and an acoustically sensitive polymer portion 2602. The distal reflective surface 2603 and the acoustically sensitive polymer portion 2602 extend across the entire sensor array 2600. This design is similar to the interferometer-based fiber optic end-sensor structure 321A of FIG. 5B. In other embodiments, any suitable fiber optic end-sensor structure of this disclosure may be adapted for the on-chip fiber optic sensor array 2600. In an embodiment, each optical waveguide 2601 may include a Bragg grating 2612. In an embodiment, the fiber optic sensor array 2600 may be manufactured by mounting individual optical fibers to a substrate, optionally performing one or more operations to smooth the surfaces of the optical fibers, and then applying the distal reflective surface 2603 and the acoustically sensitive polymer portion 2602. In embodiments, the fiber optic sensor array 2600 can be fabricated, for example, using UV lithography or other suitable additive manufacturing techniques to write the optical waveguide 2601. Therefore, in embodiments, at least a portion of the fiber optic sensor array 2600 can be formed from the chip (e.g., a substrate) itself. In other embodiments, such as Figure 27B As shown, the fiber optic sensor array 2600 can be formed from a plurality of fiber optic sensor arrays 2600A, 2600B, and 2600C forming one array 2600. Each of the fiber optic sensor arrays 2600A, 2600B, and 2600C can be formed on a separate chip or substrate and arranged side-by-side to form a single array 2600. In an embodiment, the distal reflective surface 2603 and the acoustically sensitive polymer portion 2602 can be applied continuously across the plurality of fiber optic sensor arrays 2600A / B / C (e.g., Figure 27B (As shown in the figure). In an embodiment, the distal reflective surface 2603 and the acoustically sensitive polymer portion 2602 may be applied to each of the plurality of fiber optic sensor arrays 2600A / B / C respectively before they are aligned. The fiber optic sensor arrays 2600 may be linear (as shown) or curved.

[0215] The on-chip fiber optic sensor array 2600 is oriented such that acoustic waves are incident on the distal reflective surface 2603. Alternatively, the on-chip fiber optic sensor array 2600 can be oriented such that acoustic waves are incident along the length of the distal portion of the optical waveguide 2601, including the Bragg grating 2612. In such an arrangement, the Bragg grating can be an acoustically sensitive Bragg grating, such as the acoustically sensitive Bragg grating disclosed in pending U.S. Application 63 / 522,793, filed June 23, 2023, entitled "Optical Fiber with Acoustically Sensitive Fiber Bragg Gratings".

[0216] Figure 28 A and 28B illustrate the structure of a hybrid array probe module according to embodiments herein. Figure 28 A shows a cross-sectional view of probe module 2801. Figure 28 B provides an enlarged version. As shown, dimension A represents the axial dimension of probe module 2801, i.e., the overall direction of acoustic energy transmission and reception. Dimension E represents the elevation or height dimension of probe module 2801. Dimension L, perpendicular to the page, represents the lateral dimension of probe module 2801. Generally, probe module 2801 extends further in lateral dimension L than in elevation dimension E. The hybrid array probe module 2801 includes a fiber optic sensor array 2830, which includes multiple fiber optic sensors 2820 having fiber optic end sensors 2810 mounted to substrate 2812 and optical waveguides 2811. The multiple fiber optic sensors 2820 can be similar to... Figure 25E or Figure 27A or Figure 27B The fiber optic sensor array 2830 can be mounted to the substrate in any suitable manner, as shown in the figures, or in any other suitable manner to ensure that the optical fibers form an array with the desired spacing and geometry. The fiber optic sensor array 2830 can be configured in any suitable manner consistent with the embodiments herein, and the structures shown in these figures can be modified to adapt, for example, in… Figures 25A-25D Different array shapes are disclosed herein. The fiber optic sensor 2820 can be any type of fiber optic sensor 2820 having the fiber optic end sensors discussed herein. The fiber optic sensor 2820 is mounted to a substrate 2812, which may include, for example, regarding... Figure 25E or Figure 27A or Figure 27BA substrate is shown and described. The fiber optic sensor 2820 is arranged such that the fiber optic end sensor 2810 is oriented in the axial dimension. The fiber optic sensor 2820 may be disposed behind or within an interface layer 2813, which may further include an acoustic matching layer and / or an acoustic lens. The interface layer 2813 contacts the surface of the region to be imaged and is made of a biocompatible material with minimal acoustic impedance, which also serves as a moisture barrier and electrical insulator. The interface layer 2813 may further include an acoustic matching layer selected to perform acoustic impedance matching with the target environment to reduce acoustic reflections at the interface between the interface layer 2813 and the target environment. In an embodiment, the interface layer 2813 may be further configured to include an acoustic lens to help focus / direct the received acoustic signal to the fiber optic end sensor 2810. Finally, the interface layer 2813 may include a coupling agent made of a low-attenuation and impedance-matched material, such as a flexible or rigid elastomer. Interface layer 2813 may be a single or multiple components attached via adhesive, and / or may be molded to the fiber optic sensor array 2830 in place. Interface layer 2813 may be configured such that there is no air gap between interface layer 2813 and the portion of the fiber optic end sensor 2810 that will sense the signal, for example, such that interface layer 2813 and fiber optic end sensor 2810 are in contact with each other. In embodiments, interface layer 2813 may be disposed within a transducer housing or as part of a transducer housing as an outer layer of the transducer device between the fiber optic sensor array 2830 and the surrounding environment. Furthermore, interface layer 2813 provides protection for optical sensor 2820.

[0217] The hybrid array probe module 2801 may further include an AEG array 2815 and an interface layer 2814, mounted to a suitable substrate separate from the substrate 2812, in accordance with the disclosure herein. In other embodiments, the AEG array 2815 and the fiber optic sensor 2820 may be mounted to a single substrate. Like the interface layer 2813, depending on the desired performance of the AEG array and the materials comprising the AEG array, the interface layer 2814 may include an acoustic matching layer, an acoustic coupling agent, and / or an acoustic lens. The acoustic impedance matching layer reduces acoustic reflections at the interface between the array and the imaging target environment. In embodiments, the interface layer 2814 may further include and / or be configured as an acoustic lens to help focus / direct acoustic signals transmitted and received by the AEG array. The interface layer 2814 may be integrated with or separate from the interface layer 2813. In embodiments, the interface layer may be a single integrated component of multiple different materials or a single integrated component of a single material. In an embodiment, the interface layer 2814 may be disposed within the transducer housing as an outer layer of the transducer device between the AEG array 2815 and the surrounding environment, or may be disposed as part of the transducer housing.

[0218] Figure 29A and 29B illustrate the structure of a hybrid array probe module according to embodiments herein. Figure 29 A shows a cross-sectional view of probe module 2901. Figure 29B provides an enlarged version. As shown, dimension A represents the axial dimension of probe module 2901, i.e., the overall direction of acoustic energy transmission and reception. Dimension E represents the elevation or height dimension of probe module 2901. Dimension L, perpendicular to the page, represents the lateral dimension of probe module 2901. Generally, probe module 2901 extends further in the lateral dimension L than in the elevation dimension E. Hybrid array probe module 2901 includes an optical fiber sensor array 2930, which includes multiple optical fiber sensors 2920 mounted to a substrate 2912 with optical fiber end sensors 2910 and optical waveguides 2911. The optical fiber sensors 2920 can be any type of optical fiber sensor 2920 having optical fiber end sensors discussed herein. The optical fiber sensors 2920 are mounted to the substrate 2912, which may comprise two portions to accommodate the optical fiber sensors 2920. The optical fiber sensors 2920 are arranged such that the optical fiber end sensors 2910 are oriented in the elevation dimension. Therefore, substrate 2912 is configured to maintain the curvature of optical waveguide 2911 to redirect the dimension of the distal portion of fiber optic sensor 2920 from the axial dimension (as required to extend through the probe) to the elevation dimension. Fiber optic end sensor 2910 may comprise the fiber optic end sensor described herein, arranged in a side-view or front-view configuration relative to optical waveguide 2911, utilizing the wide field of view provided by the fiber optic end sensor described herein. Fiber optic sensor 2920 may be disposed behind or within interface layer 2913 and secured by optical fastener 2917. Optical fastener 2917 is configured to secure fiber optic sensor 2920 to substrate 2912 and, in some embodiments, may be integral with interface layer 2913. Interface layer 2913 contacts the surface of the region to be imaged and is made of a biocompatible material with minimal acoustic impedance, which also serves as a moisture barrier and electrical insulator. Interface layer 2913 may further comprise an acoustic matching layer and / or an acoustic lens. Interface layer 2913 is composed of one or more materials selected to be acoustically impedance matched to the target environment to reduce acoustic reflections at the interface between interface layer 2913 and the target. Fiber optic sensor array 2930 may be mounted to or may include mechanical sublayer 2950 to facilitate integration within the probe. The fiber optic sensor array may further include optical backing block 2916 configured to provide acoustic isolation and damping, for example, to prevent internal acoustic reflections within the probe from bouncing back to the fiber-optic end sensor 2910. Furthermore, interface layer 2913 provides protection for optical sensor 2920. Hybrid array probe module 2901 further includes an AEG array 2915 conforming to the disclosure herein and interface layer 2914. Interface layer 2914 contacts the surface of the area to be imaged and is made of a biocompatible material with minimal acoustic impedance, which also serves as a moisture barrier and electrical insulator. Interface layer 2914 may include an acoustic matching layer and / or acoustic lenses.In embodiments, interface layers 2913 and 2914 may be disposed within a transducer housing or as part of a transducer housing, respectively, as outer layers of the transducer device between the fiber optic sensor array 2930 or the AEG array 2915 and the surrounding environment. Interface layers 2913 and 2914 may each include some or all of the features described with respect to interface layers 2813 and 2814.

[0219] Figure 30 A and 30B illustrate the structure of a hybrid array probe module according to embodiments herein. Figure 30 A shows a cross-sectional view of the probe module 3001. Figure 30 B provides an enlarged version. As shown, dimension A represents the axial dimension of probe module 3001, i.e., the overall direction of acoustic energy transmission and reception. Dimension E represents the elevation or height dimension of probe module 3001. Dimension L, perpendicular to the page, represents the lateral dimension of probe module 3001. Generally, probe module 3001 extends further in the lateral dimension L than in the elevation dimension E. The hybrid array probe module 3001 includes a pair of fiber optic sensor arrays 3030, each containing multiple fiber optic sensors 3020 mounted to a substrate 3012 with fiber optic end sensors 3010 and optical waveguides 3011. The fiber optic sensor arrays 3030 are, for example, according to... Figure 25C The structural configuration is shown. In an embodiment, the same structure can be rearranged to accommodate... Figure 25D The structure is shown. In the embodiment, the concept shown in probe module 3001 can be applied to any probe module discussed herein to realize a probe module having a pair of fiber optic sensor arrays. Fiber optic sensor 3020 can be any type of fiber optic sensor 3020 having the fiber optic end sensors discussed herein. Fiber optic sensor 3020 is mounted to substrate 3012, which may contain, for example, regarding... Figure 25EA substrate is shown and described. The fiber optic sensor 3020 is arranged such that the fiber optic end sensor 3010 is oriented in the axial dimension (but, as mentioned, elevation dimension orientation may also be covered). The fiber optic sensor 3020 may be disposed behind or within the interface layer 3013. The interface layer 3013 contacts the surface of the region to be imaged and is made of a biocompatible material with minimal acoustic impedance, which also serves as a moisture barrier and electrical insulator. The interface layer 3013 may further include an acoustic matching layer and / or an acoustic lens. The interface layer 3013 is selected to be acoustically impedance matched to the target environment to reduce acoustic reflections at the interface between the interface layer 3013 and the target. Furthermore, the interface layer 3013 provides protection for the optical sensor 3020. The hybrid array probe module 3001 further includes an AEG array 3015 conforming to the disclosure herein and may include an interface layer 3014. Interface layer 3014 contacts the surface of the area to be imaged and is made of a biocompatible material with minimal acoustic impedance, which also serves as a moisture barrier and electrical insulator. Interface layer 3014 may further include an acoustic matching layer and / or an acoustic lens. In embodiments, interface layers 3013 and 3014 may be disposed within or as part of a transducer housing as outer layers of the transducer device between the fiber optic sensor array 3030 or the AEG array 3015 and the surrounding environment. Interface layers 3013 and 3014 may each include some or all of the features described with respect to interface layers 2813 and 2814. The AEG array 3015 may be arranged between the two optical sensor arrays 3030.

[0220] Figure 31 and 32 An embodiment of a polarization-based fiber optic sensor array transducer conforming to this disclosure is shown. Figure 31A polarization-based fiber optic sensor array transducer 2700 is illustrated. The polarization-based fiber optic sensor array transducer 2700 may include a polarization-based fiber optic sensor array 2701 and a transmission array 2750, such as an AEG element array, for transmitting and receiving acoustic signals. The polarization-based fiber optic sensor array 2701 may be contained within a single optical fiber arranged transversely to the transmission array 2750, such that the polarization-based fiber optic sensor array 2701 is substantially perpendicular to the direction of acoustic signal transmission. The polarization-based fiber optic sensor array 2701 may include multiple Bragg reflectors 2702, each configured to reflect light of a different wavelength. As discussed above, the polarization-based sensor can be sensitive to acoustic signals received from a direction substantially perpendicular to the polarization-based fiber optic sensor array transducer 2700. Because each Bragg reflector 2702 reflects light of a different wavelength, when the polarization-based fiber optic sensor array 2701 receives light of multiple wavelengths, there is a mixture of different wavelengths within the polarization-based fiber optic sensor array 2701 before each Bragg reflector 2702. Therefore, acoustic signals incident on different points along the length of the polarization-based fiber optic sensor array 2701 can be measured based on variations in the wavelengths of the reflected light. The transmission array 2750 can emit acoustic signals, and the polarization-based fiber optic sensor array 2701 can receive reflections of these signals. The reflected acoustic signals can be incident on different locations along the length of the polarization-based fiber optic sensor array 2701, and can therefore be detected according to the principles of polarization-based sensors described herein. In embodiments, the polarization-based fiber optic sensor array 2701, which may comprise a single optical fiber, can be arranged to be perfectly aligned with the transmission array 2750 (in the axial direction). In such embodiments, appropriate acoustic damping and matching materials can be provided between the transmission array 2750 and the fiber optic sensor array 2701, or between the fiber optic sensor array 2701 and the acoustic lens, to minimize noise and / or acoustic reflections. Figure 31 The design reduces the footprint because only one fiber optic sensor array 2701 is needed (but additional fiber optic sensor arrays 2701 can also be used). Figure 31 The design allows it to be used with a dedicated back-end system configured to demultiplex signals received from the sensor array 2701.

[0221] Figure 32A polarization-based fiber optic sensor array transducer 2720 is shown. The polarization-based fiber optic sensor array transducer 2720 may include a polarization-based fiber optic sensor array 2721 and a transmission array 2750, such as an AEG element array. The polarization-based fiber optic sensor array 2721 includes a plurality of individual fiber optic sensors 2722 configured to detect polarization-based acoustic signals according to the method described herein. The polarization-based fiber optic sensor array 2721 may be arranged laterally to the transmission array 2750 such that the polarization-based fiber optic sensor array 2721 is substantially perpendicular to the direction of propagation of the acoustic signal. Lateral orientation may be facilitated by optical fasteners 3217 configured to facilitate or provide reorientation of the fiber optic sensors 2722 from axial orientation (for extension through the probe) to lateral orientation. Optical fasteners 3217 may be disposed on either side of the polarization-based fiber optic sensor array 2721, and in embodiments, two optical fasteners 3217 may be included, one on each side of the polarization-based fiber optic sensor array 2721. In one embodiment, individual fiber optic sensors 2722 may be arranged such that they are in contact with each other without gaps or other materials between them. In another embodiment, individual fiber optic sensors 2722 may be arranged such that they are not in contact with each other, and gaps between individual fiber optic sensors 2722 may be filled with or by a suitable material having a similar or matching acoustic impedance. In another embodiment, the polarization-based fiber optic sensor array 2721 may be encapsulated or covered with a suitable material having a similar or matching acoustic impedance. Each of the plurality of individual fiber optic sensors 2722 includes an exposure window 2723. The exposure windows 2723 are arranged such that different portions along the length of the polarization-based fiber optic sensor array 2721 have exposure windows 2723 capable of receiving and detecting acoustic signals. In another embodiment, the exposure windows 2723 may be arranged such that all portions along the length of the polarization-based fiber optic sensor array 2721 are associated with at least one exposure window 2723. In another embodiment, the exposure windows 2723 may overlap. In yet another embodiment, the exposure windows 2723 do not overlap, but are arranged such that there are no exposure gaps along the length of the polarization-based fiber optic sensor array 2721. In other embodiments, exposure gaps may exist along the length of the polarization-based fiber optic sensor array 2721 between exposure windows. Therefore, acoustic signals incident on the polarization-based fiber optic sensor array 2721 at different points along its length (e.g., different exposure windows 2723) can be measured based on which of the individual fiber optic sensors 2722 receives and detects the acoustic signal. The transmission array 2750 can transmit acoustic signals, and the polarization-based fiber optic sensor array 2721 can receive reflections of these signals.The reflected acoustic signal can be incident on different locations along the length of the polarization-based fiber optic sensor array 2721, and can therefore be detected according to the principles of polarization-based sensors described herein. The fiber optic sensor array transducer 2720 can be advantageous because the fiber optic sensor array 2721 involves multiple fibers, eliminating the need for demultiplexing. Since the individual fiber optic sensor 2722 is much smaller than an AEG element (less than 1 / 10, less than 1 / 20), it may not be necessary to reduce the footprint by using fewer fibers.

[0222] Figure 33 A, 33B, and 33C illustrate the structure of a hybrid array probe module according to embodiments herein. Figure 33 A, 33B, and 33C show the inclusion of conforming Figure 31 The probe module of the polarization-based fiber optic sensor array transducer 2700. Figure 33 A shows a cross-sectional view of probe module 3301. Figure 30 B offers a larger version. Figure 33 C shows the probe module viewed in the axial dimension. As shown, dimension A represents the axial dimension of probe module 3301, i.e., the overall direction of acoustic energy transmission and reception. Dimension E represents the elevation or height dimension of probe module 3301. Dimension L, perpendicular to the page, represents the lateral dimension of probe module 3301. Generally, probe module 3301 extends further in the lateral dimension L than in the elevation dimension E. The hybrid array probe module 3301 includes a polarization-based fiber optic sensor array 3330, which includes a fiber optic sensor 3320 at the end of optical waveguide 3311 in a manner similar to a polarization-based fiber optic sensor array transducer 2700, the fiber optic sensor having a Bragg grating disposed along its length. The fiber optic sensor 3320 is mounted to a substrate 3312, the substrate may contain, for example, similar to... Figure 25EA substrate is shown and described. The fiber optic sensor 3320 is arranged such that it is oriented in the lateral dimension. This orientation is facilitated by an optical fastener 3317 configured to facilitate or provide the fiber optic sensor 3320 to be reoriented from axial orientation (for extension through the probe) to lateral orientation. The optical fastener 3317 may be disposed on either side of the hybrid array probe module 3301, and in embodiments, two optical fasteners 3317 may be included, one on each side of the hybrid array probe module 3301. In embodiments, the substrate 3312 may comprise a material that enhances acoustic damping and minimizes acoustic reflections to reduce or prevent acoustic echoes from occurring within the probe itself. The fiber optic sensor 3020 may be disposed behind or within an interface layer 3313. The interface layer 3013 contacts the surface of the area to be imaged and is made of a biocompatible material with minimal acoustic impedance, which also serves as a moisture barrier and electrical insulator. The interface layer 3013 may further comprise an acoustic matching layer and / or an acoustic lens. Furthermore, interface layer 3313 provides protection for optical sensor 3320. Hybrid array probe module 3301 further includes an AEG array 3315 conforming to the disclosure herein and interface layer 3314. Interface layer 3314 may include suitable components and materials. In embodiments, the design of probe module 3301 may be modified to accommodate multiple polarization-based fiber optic sensors, depending on the design of polarization-based fiber optic sensor array transducer 2700. In embodiments, interface layers 3313 and 3314 may be disposed within a transducer housing or as part of a transducer housing, respectively, as outer layers of the transducer arrangement between fiber optic sensor array 3330 or AEG array 3315 and the surrounding environment. Interface layers 3313 and 3314 may each include some or all of the features described with respect to interface layers 2813 and 2814.

[0223] Figure 34A polarization-based fiber optic sensor array transducer 2730 is shown. The polarization-based fiber optic sensor array transducer 2730 may include a polarization-based fiber optic sensor array 2731 and a transmission array 2750, such as an AEG element array. The polarization-based fiber optic sensor array 2731 includes a plurality of individual fiber optic sensors 2732 configured to detect polarization-based acoustic signals according to the method described herein. The polarization-based fiber optic sensor array 2731 may be arranged substantially parallel to the transmission (AEG) array 2750, such that the plurality of individual fiber optic sensors 2732 are substantially parallel (e.g., parallelism deviation not exceeding 10 degrees) to the direction of acoustic signal transmission. An end of each of the plurality of individual fiber optic sensors 2732 may be exposed to receive acoustic signals. An acoustic shield 2733 may be positioned across the polarization-based fiber optic sensor array 2731 to limit the acoustic signals incident on the polarization-based fiber optic sensor array 2731 away from the exposed end portion (which may also be referred to as an acoustic window). Therefore, acoustic signals incident on different points along the length of the polarization-based fiber optic sensor array 2731 (e.g., different individual fiber optic sensors 2732) can be measured based on which of the individual fiber optic sensors 2732 receives and detects the acoustic signal. The transmission array 2750 can transmit acoustic signals, and the polarization-based fiber optic sensor array 2731 can receive reflections of these signals. The reflected acoustic signals can be incident on different locations along the length of the polarization-based fiber optic sensor array 2731, and can therefore be detected according to the principles of polarization-based sensors described herein.

[0224] Figure 35 A, 35B, and 35C illustrate the structure of a hybrid array probe module according to embodiments herein. Figure 35 A, 35B, and 35C show the conforming to Figure 34 The probe module of the polarization-based fiber optic sensor array transducer 3500. Figure 35 A shows a cross-sectional view of probe module 3501. Figure 35 B offers a larger version. Figure 35 C shows the probe module viewed in the axial dimension. As shown, dimension A represents the axial dimension of probe module 3501, i.e., the overall direction of acoustic energy transmission and reception. Dimension E represents the elevation or height dimension of probe module 3501. Dimension L, perpendicular to the page, represents the lateral dimension of probe module 3501. Generally, probe module 3501 extends further in the lateral dimension L than in the elevation dimension E. The hybrid array probe module 3501 includes a polarization-based fiber optic sensor array 3530, which includes multiple fiber optic sensors 3520 in a manner similar to a polarization-based fiber optic sensor array transducer 2730. The fiber optic sensors 3520 are mounted to a substrate 3512, which may contain, for example, components similar to those described above. Figure 25EThe substrate is shown and described. Fiber optic sensors 3520 are arranged such that they are oriented in the elevation dimension, wherein the exposed end portion 3510 is configured to receive reflected acoustic signals. The exposed end portion 3510 is the portion of the fiber optic sensor 3520 that has an exposed or acoustic window (e.g., a portion where the cladding or encapsulation is removed or reduced, as per [reference to...]). Figure 6D and 6DD As described, to allow acoustic signals to be transmitted into the fiber optic sensor 3520. This orientation is facilitated by an optical fastener 3516 configured to facilitate or provide the fiber optic sensor 3520 to be reoriented from axial orientation (for extension through the probe) to elevation orientation. The optical fastener 3516 may be configured to be acoustically reflective, preventing acoustic signals from reaching the exterior of the end portion 3510 of the fiber optic sensor 3520. In an embodiment, the substrate 3512 may contain a material that enhances acoustic damping and minimizes acoustic reflections to reduce or prevent acoustic echoes from occurring within the probe itself. The fiber optic sensor 3520 may be disposed behind or within an interface layer 3513. The interface layer 3513 may contain all the features of the interface layer described above, such as interface layer 2813. The interface layer 3513 contacts the surface of the area to be imaged and is made of a biocompatible material with minimal acoustic impedance, which also serves as a moisture barrier and electrical insulator. The interface layer 3513 may further include an acoustic matching layer and / or an acoustic lens. In other embodiments, the interface layer 3513 with acoustic lenses has different (e.g., increased) beam steering properties compared to other interface layers described herein, to address a larger signal receiving area via the exposed end portion 3510. The interface layer 3513 is selected to be acoustically impedance matched to the target environment to reduce acoustic reflections at the interface between the interface layer 3513 and the target. Furthermore, the interface layer 3513 provides protection for the exposed end portion 3510. The fiber optic sensor array 3530 may further include an optical backing block 3525 configured to provide acoustic isolation and damping, for example, to prevent internal acoustic reflections within the probe from bouncing back to the fiber optic sensor 3520. The fiber optic sensor array 3530 may be mounted to or may include a mechanical sublayer 3550 to facilitate integration within the probe. In embodiments, the mechanical sublayer 3550 and / or the substrate 3512 may also include acoustic isolation and / or damping characteristics. The hybrid array probe module 3501 further includes an AEG array 3515 conforming to the disclosure herein and an interface layer 3514, the interface layer potentially including a matching layer and / or an acoustic lens. In embodiments, interface layers 3513 and 3514 may be disposed within a transducer housing or as part of a transducer housing, respectively, as outer layers of a transducer device between the fiber optic sensor array 3530 or the AEG array 3515 and the surrounding environment. Interface layers 3513 and 3514 may each include some or all of the features described with respect to interface layers 2813 and 2814.

[0225] Figure 36 A photoacoustic sensor system for use with an optical fiber sensor is shown. The photoacoustic sensor system 3600 includes features for promoting… Figure 28 The components, devices, hardware, and software used in the hybrid sensor array 3661 of any of A-30B. In embodiments, for example, such as... Figure 36 As shown, the photoacoustic sensor system 3600 may include hardware and components for facilitating both acoustic and optical use of the hybrid sensor array 3661. The photoacoustic sensor system 3600 may include a processing system 3650, an optical subsystem 3615, and a hybrid array transducer probe 3660 incorporating the hybrid sensor array 3661.

[0226] The processing system 3650 may include a processing unit 3609 and an image reconstruction unit 3606. The processing unit 3609 may include at least one computer processor, at least one non-transitory computer-readable storage medium, and suitable software instructions. The processing unit 3609 is configured to provide control signals to and receive information signals from the light source control unit 3607, the light receiving device 3603, and the acoustic control unit 3622. The processing unit 3609 can communicate with the light source control unit 3607 (via control signals and information signals) to control the light signals provided to the photoacoustic sensor system 3600. The processing unit 3609 can communicate with the acoustic control unit 3622 (via control signals and information signals) to control and receive acoustic signals via the AEG array 3645 of the hybrid sensor array 3661. The processing unit 3609 is further configured to communicate with the light receiving device 3603 to receive information signals associated with the light signals received by the light receiving device 3603. Therefore, the processing unit 3609 is used to provide the necessary control signals and receive the information signals acquired in the photoacoustic sensor system 3600.

[0227] Processing unit 3609 further communicates with image reconstruction unit 3606, which generates an image based on data and / or information acquired by processing unit 3609. Image reconstruction unit 3606 may generate an image based on data associated with a medium, such as a human body, captured by hybrid sensor array 3661, which may be incorporated into hybrid sensor array transducer probe 3660. Image reconstruction unit 3606 may be integrated within a system housing processing unit 3609, and / or may be a separate system comprising at least one computer processor, at least one non-transitory computer-readable storage medium, and appropriate software instructions. Processing unit 3609 may be further configured to receive and correspond to electrical signals representing sensed or measured physical parameters, and to process and interpret the electrical signals to provide data or information associated with the physical parameters. Processing system 3650 may provide control signals to output device 3608 to provide data output. Output device 3608 may include, for example, a display or a device including a display.

[0228] In some embodiments, the output device 3608 may further include additional systems, such as medical procedure systems configured to use the output data. For example, the output device 3608 may include an endoscope system, a laparoscopic system, a robotic surgical system, a neurosurgical system, and may additionally include an interactive ultrasound imaging system.

[0229] The optical subsystem 3615 includes a light source control unit 3607, a light source 3604, optical devices 3602A, 3602B, 3602C, and 3602D, and a light receiving device 3603. The light source control unit is configured to interface with the light source 3604 and control the light source 3604 to control the generation of an initial optical signal 3611. The light source 3604 may include multiple working lasers or an array of working lasers, each working laser configured to provide the initial optical signal 3611 to the fiber optic sensors in the optical sensor array 3601. The initial optical signal 3611 may have a series of frequencies / wavelengths and / or polarizations. Therefore, the light source 3604 may include a laser array configured to generate laser light in one or more modes and at one or more frequencies. Furthermore, the polarization of the supplied light can be controlled according to application requirements to optimize the detected signal level. The polarization state of the light can be controlled to be linearly polarized at a specific angle or controlled to be circularly polarized. Linearly polarized light responds best to input ultrasound from a specific direction, while circularly polarized light responds to ultrasound from all directions. The polarization of light can be defined from the output of the laser source, and the output polarization state can be controlled by an in-line fiber polarizer, a paddle fiber polarization controller, an in-line fiber polarization controller, or other types of polarization controllers. Optical devices 3602A, 3602B, and 3602C can be configured to manipulate or influence the initial optical signal 3611 received at the optical sensor array 3601. Optical device 3602A may include, for example, a wavelength division multiplexing (WDM) device configured to multiplex the initial optical signal 3611 provided by the light source 3604 for simultaneous transmission via an optical waveguide 3605 that directs the initial optical signal 3611 to the optical sensor array 3601. Optical device 3602B may be a circulator with first, second, and third ports, wherein the first port is in optical communication with the light source via the wavelength division multiplexing (WDM) device 3602A. In discussing the optical circulator 3602B, optical components such as optical couplers can actually be used. An initial optical signal 3611 (multiplexed for transmission through a single waveguide) can be transmitted through a second optical device 3602B, which may be, for example, an optical circulator configured to direct the initial optical signal 3611 to an optical device 3602C. The optical device 3602C may include a WDM device configured to demultiplex the initial optical signal 3611, such that each of the plurality of fiber optic sensors within the optical sensor array 3601 receives and subsequently outputs its own individual optical signal. The optical device 3602C communicates optically with a second port of the second optical device 3602B to divide the initial optical signal 3611 into multiple optical signals destined for the optical sensor array 3601 and to combine the optical signals returning from the optical sensor array 3601.Next, these returned optical signals are directed to optical device 3602D through the third port of the second optical device 3602B. Optical device 3602D may include a WDM device configured to demultiplex the reflected optical signal 3612 again for reception at optical receiving device 3603.

[0230] The initial optical signal 3611 is received by the fiber optic sensor array 3601 and returned to the optical device 3602C via one or more optical waveguides 3605. The optical device 3602C can be further configured to multiplex the returned optical signal 3612 (if needed) for transmission to the optical receiving device 3603. The returned optical signal 3612 can be guided from the optical device 3602C to the optical device 3602D via the optical device 3602B. The optical device 3602D can be a WDM device configured to demultiplex the returned optical signal 3612 for reception by the optical receiving device 3603.

[0231] Optical device 3602D can optically communicate with the third port of optical device 3602B to receive the returned optical signal and divide it into individual wavelength components. For example, optical receiver 3603, which may be a photodetector array, can optically communicate with optical device 3602D to receive the individual wavelength components of the returned optical signal, such that the phase shift or other changes of the detected individual wavelength components indicate the sensed acoustic signal.

[0232] It should be understood that in embodiments where frequency multiplexing / demultiplexing of the initial optical signal 3611 and the returned optical signal 3612 is not required, optical devices 3602A and 3602C may not be necessary. For example, the respective transmission paths may extend between the operating laser array of the light source 3604 and the optical sensor array 3601. The optical receiver 3603 may include any suitable device configured to detect incident light, including, for example, a photodetector. The optical receiver 3603 may further include, but is not limited to, a photodiode array. The optical receiver 3603 may optically communicate with the optical device 3602D (e.g., a wavelength division multiplexing separator) to receive the respective wavelength components of the returned optical signal 3612, such that the phase shift, polarization change, or other changes of the detected respective wavelength components indicate the sensed acoustic signal. The variations in the returned optical signal 3612 can be converted (e.g., by processing unit 3609 and / or by additional optical components such as polarization-sensitive couplers and / or frequency shifters) into data representing the sensed acoustic signal, and can be further used, for example, to generate data representing tissue / anatomical structures and physical parameters using the hybrid sensor array probe 3660. In embodiments, the initial optical signal 3611 and the returned optical signal 3612 can undergo preprocessing, beamforming, and post-processing as described herein. The images and / or data provided by the optical sensor array 3601 can then be displayed to a user on an output device 3608, which may include a computer monitor, etc.

[0233] As discussed above, the light receiving device 3603 communicates with the processing unit 3609. The processing unit 3609 receives from the light receiving device 3603 an information signal representing the returned optical signal 3612 received at the light receiving device 3603. The processing unit 3609 may also receive from the light control unit 3607 an information signal representing the initial optical signal 3611 output by the light source 3604. The processing unit 3609 processes the information signal associated with the returned optical signal 3612 (optionally compared to the information signal associated with the initial optical signal 3611) to determine the acoustic environment. The acoustic environment determination may include detecting, identifying, and interpreting acoustic signals incident on the sensors in the fiber optic sensor array 3601, which may include tissue imaging and physical parameter sensing. The processing unit 3609 can determine the presence and nature of the acoustic signals incident on the fiber optic sensors in the fiber optic sensor array.

[0234] Therefore, the fiber optic array 3601 can be used to detect and / or receive acoustic (e.g., ultrasonic) signals and provide an optical signal representing and consistent with the acoustic signal to an optical receiving device 3603 via an optical receiving chain (e.g., optical devices 3602C, 3602B, 3602D). The optical receiving device is configured to detect and / or receive the optical signal and provide an electrical signal representing and consistent with the optical signal to a processing unit 3609 for processing and interpretation. Therefore, the processing unit 3609 can be configured to receive an electrical signal representing and consistent with the received acoustic signal, and process and interpret the electrical signal to reconstruct an image from the acoustic signal and / or provide sensed physical parameter data.

[0235] Processing unit 3609 can further communicate with acoustic control unit 3622. Acoustic control unit 3622 can be configured to provide control data to and receive signal data from the AEG array 3645 of the hybrid sensor array 3661. Data received by processing unit 3609 from AEG array 3645 and optical sensor array 3601 can be combined to provide an improved ultrasound image quality compared to ultrasound images provided by AEG elements alone or optical sensors alone. Example methods of combination may include, for example, a delay superposition method performed by a beamformer, individual beamformer processing of each signal, and subsequent synthesis by applying frequency filters and weighted summation. The synthesis method may vary depending on the imaging depth.

[0236] Processing unit 3609 is configured to use information signals from hybrid sensor array 3661 according to any of the embodiments disclosed herein, including for tracking, imaging, detection, physical parameter sensing, measurement, etc. Acoustic determination information can be output via output device 3608, which may be, for example, a display, another medical system, etc.

[0237] It should be understood that Figure 36 The configuration of the photoacoustic sensor system 3600 shown is provided as an example. Different configurations may be used without departing from the scope of this disclosure. For example, different arrangements of optical devices 3602A / B / C / D, different numbers and arrangements of fiber optic sensors 101, and fiber optic sensor arrays 3601 may be used. In embodiments, the light source control unit 3607 and the acoustic control unit 3622 may be incorporated into or integrated within the processing system 3650. Additional combinations of components of the photoacoustic sensor system 3600 may be selected as needed to achieve the functions described herein.

[0238] Figure 37 A photoacoustic sensor system is shown for use with a hybrid sensor array. The photoacoustic sensor system 3700 includes features for facilitating interaction with... Figure 28The components, devices, hardware, and software used in any of the consistent hybrid sensor arrays 3761 in A-30B. Some aspects of the photoacoustic sensor system 3700 are similar to those of the photoacoustic sensor system 3600, and will not be repeated. The differences are described below.

[0239] The photoacoustic sensor system includes a light source 3704, which comprises a single laser or several lasers operating at the same frequency (e.g., to enhance power). The initial optical signal from the light source 3704 is split into several channels corresponding to the number of sensors in the optical sensor array 3701 by a beam splitter 3731. The initial optical signal passes through an optical circulator array 3702, which contains several circulators corresponding to the number of fiber optic sensors, where each signal is directed to a WDM cell in the WDM array 3725. In discussing the optical circulator array 3702, optical components such as optical couplers can actually be used. If multiple operating lasers are used as the light source 3704, then multiple beam splitters 3731 can be used.

[0240] The photoacoustic sensor system also includes a heating source 3717, which comprises a single laser or several lasers operating at the same frequency (e.g., to enhance power). The heating source 3717 operates at a frequency configured for thermal absorption by the fiber optic sensors in the optical sensor array 3701, as discussed herein. The initial thermo-optical signal from the heating source 3717 is split into several channels corresponding to the number of fiber optic sensors in the optical sensor array 3701 by a beam splitter 3732. If multiple lasers are used as the heating source 3717, then multiple beam splitters 3732 can be used. The initial thermo-optical signal passes through a thermal tuning unit 3715, which is used to adjust the intensity of each thermo-optical signal to tune the individual optical sensors in the optical sensor array 3701. For example, the thermal tuning unit can be operated using an electronically variable optical attenuator (E-VOA), such as a MEMS-based VOA, a fiber-to-fiber VOA, an electro-optic VOA, or an acousto-optic VOA. The resulting tuned thermo-optical signal is provided to the WDM array 3725, multiplexed with the corresponding initial optical signal, and then provided to the appropriate optical sensor in the optical sensor array 3701. The thermal tuning unit 3715 is controlled by a thermal control unit 3714 that receives input from the optical receiver array 3703. The input from the optical receiver array 3703 is used in a feedback loop to control the heating of each fiber optic sensor in the optical sensor array 3701 (and thus control the thermal tuning properties). The thermal tuning process is described above and can be used to tune the individual fiber optic sensors in the optical sensor array 3701 to be sensitive to the same operating laser frequency.

[0241] Additional features of the photoacoustic sensor system 3700 are similar to those of the photoacoustic sensor system 3600. The returned optical signals are filtered from the thermo-optical signals and passed through a circulator array 3702, where they are directed to a light-receiving array 3703. Alternatively, the light-receiving array 3703 can be selected as a device relatively insensitive to the wavelength of the thermo-optical signal, thereby allowing the reception of these signals without unduly affecting the temperature of the light-receiving array 3703. The light-receiving array 3703 is configured to receive the plurality of returned optical signals (e.g., via individual light-receiving devices in the array, each corresponding to a channel to which the initial optical signal was separated) and provide its information and data to a processing unit 3709. The individual light-receiving devices can be, for example, individual photodetectors. The processing unit 3709 further communicates with the AEG array 3745 via an acoustic control unit 3722. Information from the AEG array 3745 and the optical sensor array 3701 is provided to the processing unit 3709 for acoustic environment determination, including, for example, imaging and sensed physical parameter data. Additionally, the processing unit 3709 can also receive output from the thermal tuning control unit 3714 for interpreting the returned optical signal. Acoustic determination information can be output via an output device 3708, which may be, for example, a display, another medical system, etc.

[0242] The photoacoustic sensor system 3700 significantly reduces the number of lasers required for the light source 3704 by splitting the optical signal from a single light source 3704 into multiple channels. This reduces the cost, size, and power consumption of the system 3700. The reduction in the total number of lasers required for the light source 3704 can represent a significant reduction in cost, size, power consumption, and complexity. In embodiments, fewer lasers than are used in fiber optic sensors (e.g., to enhance power). Each of the plurality of lasers can be tuned to the same wavelength and separated.

[0243] Figure 38 An optoacoustic sensor system is shown for use with a hybrid sensor array. The optoacoustic sensor system 3800 includes features for facilitating the use of polarization-based fiber optic sensors and... Figures 31-35 The components, devices, hardware, and software used in any consistent hybrid sensor array 3861 in C. Some aspects of the photoacoustic sensor system 3800 are similar to those of the photoacoustic sensor systems 3600 and 3700, and will not be repeated. The differences are described below.

[0244] The photoacoustic sensor system includes a light source 3804, which comprises a single laser or several lasers operating at the same frequency (e.g., to enhance power). The initial optical signal from the light source 3804 is split into several channels corresponding to the number of fiber optic sensors in the optical sensor array 3801. The initial optical signal passes through an optical circulator array 3802, which contains several circulators corresponding to the number of fiber optic sensors, wherein each signal is directed to its corresponding fiber optic sensor in the optical sensor array 3801. In discussing the optical circulator array 3802, optical components such as optical couplers can actually be used.

[0245] Additional features of the photoacoustic sensor system 3800 are similar to those of photoacoustic sensor systems 3600 and 3700, as well as system 100B described above with respect to Figure 6A. Returning optical signals pass through a circulator array 3802, where they are directed to a polarization filter array 3825. The polarization filter array 3825 is configured to receive the plurality of returned optical signals, filter them by polarization, and pass the signals to a light receiving array 3809, which may be, for example, a photodetector array. The polarization filter array 3825 may be a polarization filter or analyzer array, allowing light of a specific polarization to pass through to reach the light receiving array 3809. When the polarization of the transmitted light changes, the amplitude of the light transmitted to the light receiving array 3809 changes accordingly and can be detected. Information from the light receiving array 3809 is passed to a processing unit 3806. The processing unit 3806 further communicates with an AEG array 3845 via an acoustic control unit 3822. Information from the AEG array 3845 and the optical sensor array 3801 is provided to the processing unit 3806 for acoustic environment determination, including, for example, imaging and physical parameter sensing. The acoustic determination information can be output via an output device 3808, which may be, for example, a display, another medical system, etc.

[0246] Figure 39 A and 39B illustrate the structure of a hybrid array probe module according to embodiments herein. Figure 39 A shows a cross-sectional view of probe module 3901. Figure 39 B offers a larger version. Figure 39C provides an axial view of probe module 3901. Probe module 3901 may be part of hybrid sensor array transducer 3900, may be similar to probe module 2901, and includes many similar features. Probe module 3901 differs from probe module 2901 in that it includes a micro-heating unit or array 3930. The micro-heating unit or array 3930 may incorporate a flexible circuit with multiple heaters 3913, each heater corresponding to a single fiber optic sensor 2920 in the optical sensor array 2930. During operation, the multiple heaters 3913 of the micro-heating unit 3930 may be individually controlled to provide thermal tuning to the respective fiber optic sensor 2920 according to the methods discussed herein. The multiple heaters 3913 in the micro-heating unit 3930 may be positioned as close as possible to the corresponding respective fiber optic sensor 2920 (e.g., heater 3913 may be in contact with the corresponding sensor) and may be thermally isolated from adjacent heaters 3913 and fiber optic sensors 2920. Therefore, thermal crosstalk can be reduced, and thermal tuning of the individual fiber optic sensors 2920 can be performed more efficiently. Thus, the probe module 3901 provides thermal tuning to the optical sensor array 2930. In other embodiments, the plurality of heaters 3913 may be provided as separate heaters rather than as part of the flexible circuitry.

[0247] Figure 40 A photoacoustic sensor system for use with a hybrid sensor array is shown. The photoacoustic sensor system 4000 includes components, means, hardware, and software for facilitating the use of a hybrid sensor array 4061 employing a thermally tunable optical sensor array 4001. Some aspects of the photoacoustic sensor system 4000 are similar to those of photoacoustic sensor systems 3600, 3700, and 3800, and will not be repeated. Potentially different aspects are described below.

[0248] The photoacoustic sensor system 4000 includes a light source 4004, which comprises a single laser or several lasers operating at the same frequency (e.g., to enhance power). An initial optical signal from the light source 4004 is separated into several channels corresponding to the number of fiber optic sensors in the optical sensor array 4001. The initial optical signal passes through an optical circulator array 4002, which contains several circulators corresponding to the number of fiber optic sensors, wherein each signal is directed to its corresponding fiber optic sensor in the optical sensor array 4001. In discussing the optical circulator array 4002, optical components such as optical couplers can actually be used.

[0249] The photoacoustic sensor system 4000 further includes a thermal tuning unit 4025. The thermal tuning unit 4025 controls the respective heaters 3913 of the micro-heating unit 4030 (e.g., similar to micro-heating unit 3930) to adjust the temperature, and thus thermally tunes the respective fiber optic sensors in the optical sensor array 4001. The operation of the thermal tuning unit 4025 is notified by data from the optical receiving device 4003 according to the thermal tuning method discussed herein.

[0250] Additional features of the photoacoustic sensor system 4000 are similar to those of photoacoustic sensor systems 3600, 3700, and 3800. The returned optical signals pass through a circulator array 4002, where they are directed to a polarization filter array to reach a light receiver 4003, which may be, for example, a photodetector array. Information from the light receiver 4003 is passed to a processing unit 4006. The processing unit 4006 further communicates with an AEG array 4045 via an acoustic control unit 4022. Information from the AEG array 4045 and the optical sensor array 4001 is used by the processing unit 4006 for acoustic environment determination, including, for example, imaging. The acoustic determination information can be output via an output device 4008, which may be, for example, a display, another medical system, etc.

[0251] In other embodiments, real-time visualization of the device tip, including the fiber optic sensor, can be co-registered with diagnostic ultrasound images, eliminating the need for calibration. This breakthrough allows clinicians to confidently track the device in challenging anatomical regions. A real-time confidence indicator of the device tip's intersection with the imaging plane can be provided, specifically considering when the device tip leaves the imaging plane, ensuring accurate device tip tracking even during complex procedures. Real-time prospective visualization of the tip trajectory can be provided, offering valuable insights into the predicted path of the device tip and the visualization of its trajectory, which can be used to enhance procedural confidence and documentation. Furthermore, devices with the fiber optic sensors described herein can facilitate the display of anatomical and blood flow images from an indwelling sensor co-registered with cross-sectional images, enhancing diagnostic accuracy and confidence.

[0252] The fiber optic sensors discussed in this paper can provide high sensitivity, wide bandwidth, and wide acceptance angle to ultrasound receivers. Furthermore, fiber optic sensors do not require electronic components like those in electromechanical transducers. These characteristics enable the design and fabrication of transducer arrays with a smaller footprint. In addition, the technical capabilities of the fiber optic sensors described in this paper allow transducers to sense or identify harmonic or scattered signals that are inaccessible by existing technologies. Due to the high sensitivity and wide bandwidth of optical sensors, images generated by fiber optic sensors may also have higher spatial resolution, greater penetration depth, higher signal-to-noise ratio (SNR), better tissue harmonic imaging, and / or higher Doppler sensitivity.

[0253] Example 1 is a device comprising: a housing; a substrate mounted within the housing; a plurality of sensor optical fibers fixed to the substrate, each sensor optical fiber comprising: an optical waveguide; an optical sensor structure configured to: detect an acoustic signal and provide an optical signal corresponding to the acoustic signal to the optical waveguide; and a plurality of acoustic energy generating transducers configured to generate acoustic energy.

[0254] Example 2 is the device according to Example 1, wherein the optical sensor structure is further configured to: detect physical parameters and provide an optical signal corresponding to the physical parameters to the optical waveguide.

[0255] Example 3 is a device according to Example 1 or 2, wherein the substrate comprises: a first portion configured to cover the plurality of sensor optical fibers; and a second portion attached to the first portion and having a plurality of optical fiber sensor receiving portions corresponding to the plurality of sensor optical fibers.

[0256] Example 4 is a device according to any one of Examples 1 to 3, further comprising at least one backing block configured to provide acoustic damping and located within the housing.

[0257] Example 5 is a device according to any one of Examples 1 to 4, further comprising an interface layer disposed within the housing as an outer layer of the device between the plurality of sensor optical fibers and the surrounding environment, wherein optionally the interface layer comprises a moisture barrier, an electrical insulator, a matching layer, a coupling agent, and an acoustic lens.

[0258] Example 6 is a device according to Examples 1 to 5, further comprising an interface layer disposed within the housing as an outer layer of the device between the plurality of acoustic energy generating elements and the surrounding environment, wherein optionally the interface layer comprises one or more of a moisture barrier, an electrical insulator, a matching layer, a coupling agent, and an acoustic lens.

[0259] Example 7 is a device according to any one of Examples 1 to 6, wherein: each optical sensor structure is disposed at the end of a corresponding sensor fiber, and the plurality of sensor fibers are axially arranged within the housing.

[0260] Example 8 is a device according to any one of Examples 1 to 7, wherein the plurality of sensor optical fibers are arranged in a first row and a second row on opposite sides of the plurality of acoustic energy generating transducers.

[0261] Example 9 is a device according to any one of Examples 1 to 8, wherein: each optical sensor structure is disposed at the distal end of the corresponding sensor fiber, and the distal portions of the plurality of sensor fibers are arranged in the elevation dimension within the housing.

[0262] Example 10 is a device according to any one of Examples 1 to 9, wherein each optical sensor structure is a polarization-based fiber optic sensor.

[0263] Example 11 is a device according to any one of Examples 1 to 10, wherein the distal portions of the plurality of sensor optical fibers are arranged in the elevation dimension within the housing.

[0264] Example 12 is a device according to any one of Examples 1 to 11, wherein the distal portions of the plurality of sensor optical fibers are arranged in the lateral dimension within the housing.

[0265] Example 13 is a device according to any one of Examples 1 to 12, wherein the exposed portions of the plurality of sensor optical fibers are spaced apart in the lateral dimension.

[0266] Example 14 is a device according to any one of Examples 1 to 13, which further includes a plurality of heaters, each heater corresponding to one of the plurality of sensor optical fibers.

[0267] Example 15 is a device according to any one of Examples 1 to 14, wherein the substrate is a chip and the plurality of sensor optical fibers share a single optical sensor structure.

[0268] Example 16 is a system for generating ultrasound images, comprising: a light source configured to generate an initial optical signal; a first optical waveguide configured to guide the initial optical signal from the light source to a fiber optic acoustic sensor array configured to detect an acoustic signal; an optical receiver configured to receive a returned optical signal from the fiber optic acoustic sensor array and generate optical signal data based on the returned optical signal; a second optical waveguide configured to guide the returned optical signal to the optical receiver; an acoustic control unit configured to provide acoustic control data to an acoustic energy generating transducer array and receive acoustic signal data therefrom; and a processing system configured to receive the optical signal data and the acoustic signal data and generate data output.

[0269] Example 17 is the system according to Example 16, wherein the data output is an ultrasound image.

[0270] Example 18 is a system according to Example 16 or 17, wherein the data output includes tracking or location information.

[0271] Example 19 is a system according to any one of Examples 16 to 18, wherein the light source is a laser.

[0272] Example 20 is the system according to Example 19, which further includes at least one beam splitter configured to direct the initial optical signal to each sensor in the fiber acoustic sensor array.

[0273] Example 21 is a system according to any one of Examples 16 to 20, wherein the light source is a laser array configured to provide the initial optical signal to each sensor in the fiber acoustic sensor array.

[0274] Example 22 is a system according to any one of Examples 16 to 21, wherein the light receiving device comprises a photodetector array.

[0275] Example 23 is a system according to any one of Examples 16 to 22, further comprising at least one tuned laser configured to provide a thermo-optical signal for thermal tuning of the fiber optic acoustic sensor array.

[0276] Example 24 is a system according to any one of Examples 16 to 23, further comprising a beam splitter configured to direct the thermo-optical signal to the respective sensors of the fiber optic acoustic sensor array.

[0277] Example 25 is a system according to any one of Examples 16 to 24, further comprising at least one multiplexer configured to multiplex the thermo-optical signal with the initial optical signal.

[0278] Example 26 is a system according to any one of Examples 16 to 25, further comprising a thermal tuning unit configured to adjust the thermal tuning level provided to the fiber optic acoustic sensor array.

[0279] Example 27 is a system according to any one of Examples 16 to 26, further comprising a thermal tuning unit configured to adjust the temperature of a heater associated with the fiber optic sensor array to thermally tune the fiber optic sensor array.

[0280] Example 28 is a device comprising: a housing; a substrate mounted within the housing; a plurality of sensor optical fibers fixed to the substrate, each sensor optical fiber comprising: an optical waveguide; an optical sensor structure configured to: detect physical parameters and provide an optical signal corresponding to the physical parameters to the optical waveguide; and a plurality of acoustic energy generating transducers configured to generate acoustic energy.

[0281] Example 29 is the device according to Example 28, wherein the physical parameters include at least one of temperature and pressure.

[0282] Example 30 is the device according to Example 29, wherein the optical signal corresponding to the physical parameter of pressure corresponds to an acoustic signal.

[0283] Example 31 is a device according to any one of Examples 28 to 30, wherein a first sensor fiber among the plurality of sensor fibers has a first sensitivity to the physical parameter, and a second sensor fiber among the plurality of sensor fibers has a second sensitivity to the physical parameter that is different from the first sensitivity.

[0284] The terminology used herein is for describing particular embodiments only and is not intended to limit the invention. As used herein, unless the context clearly indicates otherwise, the singular forms “a / an” and “the” are contemplated to also include the plural forms. It should be further understood that the terms “includes and / or including” as used herein specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

Claims

1. An apparatus, the apparatus comprising: shell; Substrate, the substrate being mounted within the housing; Multiple sensor optical fibers, the multiple sensor optical fibers being fixed to the substrate, each sensor optical fiber comprising: Optical waveguide; An optical sensor structure configured to: Detecting sound signals, and The optical signal corresponding to the acoustic signal is provided to the optical waveguide, and Multiple acoustic energy generating transducers are configured to generate acoustic energy.

2. The device of claim 1, wherein the optical sensor structure is further configured to: Detect physical parameters, and An optical signal corresponding to the physical parameters is provided to the optical waveguide.

3. The apparatus of claim 1, wherein the substrate comprises: A first portion, configured to cover the plurality of sensor optical fibers; and The second part is attached to the first part and has a plurality of fiber optic sensor receiving parts corresponding to the plurality of sensor fibers.

4. The device according to claim 1, further comprising an interface layer disposed within the housing as an outer layer of the device between the plurality of sensor optical fibers and the surrounding environment.

5. The device according to claim 4, wherein the interface layer comprises one or more of a moisture-proof layer, an electrical insulator, a matching layer, a coupling agent, and an acoustic lens.

6. The device according to claim 1, further comprising an interface layer disposed within the housing as an outer layer of the device between the plurality of acoustic energy generating transducers and the surrounding environment.

7. The device of claim 6, wherein the interface layer comprises one or more of a moisture-proof layer, an electrical insulator, a matching layer, a coupling agent, and an acoustic lens.

8. The device according to claim 1, wherein: Each optical sensor structure is located at the end of the corresponding sensor optical fiber, and The multiple sensor optical fibers are axially arranged inside the housing.

9. The device according to claim 8, wherein the plurality of sensor optical fibers are arranged in a first row and a second row on opposite sides of the plurality of acoustic energy generating transducers.

10. The device according to claim 1, wherein: Each optical sensor structure is located at the distal end of the corresponding sensor optical fiber, and The distal portions of the multiple sensor optical fibers are arranged within the housing in the elevation dimension.

11. The device of claim 1, wherein each optical sensor structure is a polarization-based fiber optic sensor.

12. The device of claim 11, wherein the distal portions of the plurality of sensor optical fibers are arranged within the housing in the elevation dimension.

13. The device of claim 11, wherein the distal portions of the plurality of sensor optical fibers are arranged in the lateral dimension within the housing.

14. The device of claim 13, wherein the exposed portions of the plurality of sensor optical fibers are spaced apart in the lateral dimension.

15. The device of claim 1, further comprising a plurality of heaters, each heater corresponding to one of the plurality of sensor optical fibers.

16. The device of claim 1, wherein the substrate is a chip, and the plurality of sensor optical fibers share a single optical sensor structure.

17. A system for generating ultrasound images, the system comprising: A light source configured to generate an initial light signal; A first optical waveguide is configured to guide the initial optical signal from the light source to an array of fiber optic acoustic sensors configured to detect an acoustic signal. An optical receiving device configured to receive a returned optical signal from the fiber acoustic sensor array and generate optical signal data based on the returned optical signal; A second optical waveguide is configured to direct the returned optical signal to the optical receiving device; An acoustic control unit is configured to provide acoustic control data to an acoustic energy generating transducer array and to receive acoustic signal data from the acoustic energy generating transducer array. as well as A processing system configured to receive the optical signal data and the acoustic signal data and generate data output.

18. The system of claim 17, wherein the data output is an ultrasound image.

19. The system of claim 17, wherein the data output includes tracking or location information.

20. The system of claim 17, further comprising at least one beam splitter configured to direct the initial optical signal to the respective sensors of the fiber acoustic sensor array.

21. The system of claim 17, wherein the light source is a laser array configured to provide the initial optical signal to each sensor of the fiber acoustic sensor array.

22. The system of claim 17, further comprising at least one tuned laser configured to provide a thermo-optical signal for thermal tuning of the fiber optic acoustic sensor array.

23. The system of claim 22, further comprising a beam splitter configured to direct the thermo-optical signal to each sensor of the fiber optic acoustic sensor array.

24. The system of claim 22, further comprising at least one multiplexer configured to multiplex the thermo-optical signal with the initial optical signal.

25. The system of claim 22, further comprising a thermal tuning unit configured to adjust the thermal tuning level provided to the fiber acoustic sensor array.

26. The system of claim 17, further comprising a thermal tuning unit configured to adjust the temperature of a heater associated with the fiber optic acoustic sensor array to thermally tune the fiber optic acoustic sensor array.

27. An apparatus, the apparatus comprising: shell; Substrate, the substrate being mounted within the housing; Multiple sensor optical fibers, the multiple sensor optical fibers being fixed to the substrate, each sensor optical fiber comprising: Optical waveguide; An optical sensor structure configured to: Detect physical parameters, and The optical signal corresponding to the physical parameters is provided to the optical waveguide, and Multiple acoustic energy generating transducers are configured to generate acoustic energy.

28. The device of claim 27, wherein the physical parameter comprises at least one of temperature and pressure.

29. The device of claim 28, wherein the optical signal corresponding to the physical parameter of pressure corresponds to an acoustic signal.

30. The device of claim 27, wherein the first sensor fiber of the plurality of sensor fibers has a first sensitivity to the physical parameter, and the second sensor fiber of the plurality of sensor fibers has a second sensitivity to the physical parameter that is different from the first sensitivity.

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