A holographic imaging system for assessing ultrasound neuromodulation acoustic fields and dynamic observation method thereof

Abstract

This application discloses a holographic imaging system and its dynamic observation method for evaluating ultrasonic neuromodulation sound fields, relating to the field of neuromodulation technology. The system includes an LED light source, a single spherical mirror, an industrial camera equipped with an adjustable aperture, a water tank for supporting an ultrasonic transducer, a lifting platform, and a platform guide rail. The LED light source is positioned near the focal plane of the single spherical mirror, and the industrial camera is positioned at the focal plane on the other side of the single spherical mirror. The water tank is placed on top of the lifting platform, and the transducer is placed flat at the center of the bottom of the water tank, driven by a signal generator and a power amplifier to generate a pulsed ultrasonic field. The lifting platform is used to adjust the height of the water tank so that the single spherical mirror is completely submerged in water. The adjustable aperture of the industrial camera acts as a schlieren blade to spatially filter the converged light rays reflected by the single spherical mirror, forming a schlieren image reflecting the density gradient distribution of the ultrasonic field.

Description

Technical Field

[0001] This application relates to the field of neuromodulation technology, and in particular to a holographic imaging system for evaluating ultrasonic neuromodulation sound fields and its dynamic observation method. Background Technology

[0002] Ultrasound neuromodulation, as a non-invasive neuromodulation technology, holds great promise for brain science research and the treatment of neurological diseases. However, its clinical and research applications are limited by the lack of efficient and reliable sound field visualization and verification methods. Traditional hydrophone point-by-point scanning for three-dimensional sound field reconstruction is time-consuming and cannot meet the needs of dynamic sound field capture; while commercial schlieren equipment is bulky and expensive, making it unsuitable for the research and development and clinical scenarios of focused ultrasound neuromodulation devices. Therefore, there is an urgent need for a high-resolution, low-cost, portable holographic sound field visualization system that supports real-time imaging of dynamic sound fields. Summary of the Invention

[0003] The purpose of this application is to provide a holographic imaging system and its dynamic observation method for evaluating the sound field of ultrasound neuromodulation, which has high spatiotemporal resolution and can better assist in the diagnosis and measurement of the sound field of ultrasound neuromodulation system.

[0004] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a holographic imaging system for evaluating ultrasound neuromodulation sound fields, comprising: LED light source (6), single spherical reflector (5), industrial camera (1) with adjustable aperture, water tank (3) for carrying ultrasonic transducer (7), lifting platform (4) and platform guide rail (8); The LED light source (6) and the industrial camera (1) are both mounted on the platform guide rail (8) and located on the same side of the single spherical reflector (5) to form a reflective schlieren light path; The LED light source (6) is located near the focal plane of the single spherical mirror (5), and the industrial camera (1) is located on the other side of the focal plane of the single spherical mirror (5). The water tank (3) is placed on top of the lifting platform (4) and filled with distilled water. The transducer (7) is placed flat in the center of the bottom of the water tank (3) and is driven by the signal generator and power amplifier to generate a pulsed ultrasonic field. The lifting platform (4) is used to adjust the height of the water tank (3) so that the single spherical reflector (5) is completely submerged in the water; The adjustable aperture of the industrial camera (1) serves as the schlieren blade, which performs spatial filtering on the light rays that converge after being reflected by the single spherical mirror (5) to form a schlieren image that reflects the density gradient distribution of the ultrasonic field.

[0005] Optionally, the single spherical mirror (5) is used to simultaneously perform the functions of collimation and focusing of light.

[0006] Optionally, the bracket of the industrial camera (1) has a five-degree-of-freedom adjustment function for adjusting the position and attitude of the camera; both the LED light source (6) and the industrial camera (1) can move on the platform guide rail (8).

[0007] Optionally, an acoustic metasurface is installed on the transducer (7), the acoustic metasurface including a single-point focusing metasurface, a double-point focusing metasurface and a single-sided single-point focusing metasurface.

[0008] Optionally, it also includes: a display (2) connected to an industrial camera (1) via a GigE interface for real-time display of ultrasonic field schlieren images and for processing and analysis.

[0009] Secondly, this application also provides a dynamic observation method based on the aforementioned holographic imaging system for evaluating ultrasound neuromodulation sound fields, comprising: S1. Connect the power supply of the industrial camera (1) and the monitor (2), and adjust the aperture of the industrial camera (1) to the minimum; lower the lifting platform (4) to the lowest position, and slowly raise the water tank (3) so that the single spherical mirror (5) is completely submerged in the water, and remove the air bubbles from the surface of the water tank (3) and the single spherical mirror (5). S2. Place the LED light source (6) at a set position on one side of the focal plane of the single spherical mirror (5), and place the industrial camera (1) at the focal plane on the other side to form a reflective schlieren light path; adjust the industrial camera (1) so that a bright spot appears in the display (2) and its lower edge is located in the center of the display (2). S3. Start the transducer (7) to generate a pulsed ultrasonic field. The light emitted by the LED light source (6) is deflected by the refractive index gradient inside the water tank (3). After being reflected by the single spherical mirror (5), it converges at the aperture position of the camera (1). After being filtered by the aperture, a schlieren image with light and dark distribution is formed on the camera image plane, and the spatial morphology and dynamic evolution process of the ultrasonic field are displayed in real time.

[0010] Optionally, it also includes: S4: Establish a quantitative relationship model between schlieren image brightness and acoustic pressure gradient; based on the linear relationship between refractive index and medium density, combined with geometric optics, determine the proportional relationship between the change in schlieren image brightness and the integral of acoustic pressure gradient along the optical path; calibrate the holographic imaging system through single-point hydrophone measurement and determine the proportional coefficient.

[0011] Optionally, the formula for the proportional relationship between the brightness change of the schlieren image and the integral of the sound field pressure gradient along the optical path is as follows: ; In the formula, The angle between the outgoing ray and the incident ray. It is the tiny arc length along the path of light propagation. Let be the position vector of a point on the ray; This represents the gradient of the sound field pressure along the Z-axis.

[0012] Optionally, S2 specifically includes: By adjusting the lifting platform (4), the single spherical mirror (5) is immersed in water, and by combining the mirror angle deflection and optical path height fine adjustment, the reflection image on the surface of the water tank (3) and the shadow artifacts in the holographic imaging system are eliminated.

[0013] Optionally, S3 specifically includes: By utilizing the millisecond-level temporal resolution of the schlieren system, combined with a high-brightness LED light source and an industrial camera, real-time capture of the transient establishment process and steady-state sound field morphology of the pulse sound field in ultrasonic neuromodulation can be achieved.

[0014] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides a holographic imaging system and its dynamic observation method for evaluating the acoustic field of ultrasonic neuromodulation. The system includes an LED light source, a single spherical mirror, an industrial camera equipped with an adjustable aperture, a water tank for supporting the ultrasonic transducer, a lifting platform, and a platform rail. Light emitted from the LED light source is collimated by the single spherical mirror, passes through the water tank, and then through the pulsed acoustic field region generated by the ultrasonic transducer, ultimately being captured by the industrial camera. The lifting platform is mounted on the platform rail and can move the water tank along the rail to scan and acquire acoustic field regions at different locations. Based on the schlieren imaging principle, this system, with its millisecond-level temporal resolution, can completely capture the acoustic field evolution process from the generation to steady state of an ultrasonic pulse. It can intuitively and clearly present the spatial distribution of the ultrasonic neuromodulation acoustic field under different parameters, solving the problem of existing technologies' difficulty in dynamically observing the transient establishment process of pulsed ultrasound. This provides an intuitive and reliable observation basis for acoustic field calibration and parameter optimization in ultrasonic neuromodulation. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the experimental setup for the schlieren method in a 4f system. Figure 2A schematic diagram of a holographic imaging system for evaluating an ultrasound neuromodulation sound field, provided as an embodiment of this application; Figure 3 This is a schematic diagram of a schlieren image provided in an embodiment of this application; Figure 4 This is a schematic diagram of a schlieren system provided in an embodiment of this application; Figure 5 This is a schlieren system calibration diagram provided in an embodiment of this application.

[0017] Figure label: 1-Industrial camera, 2-Display, 3-Water tank, 4-Lifting platform, 5-Single spherical reflector, 6-LED light source, 7-Transducer, 8-Platform guide rail. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] In existing technologies, the Schlieren method is an imaging technique that converts density gradients in a transparent medium into light intensity distributions, and it is widely used in aerodynamics, combustion diagnostics, and other fields. Its physical basis is that light refracts when propagating in a non-uniform medium, and the deflection angle is proportional to the density gradient. A typical Schlieren system includes a light source, a lens (or mirror), a blade, and an imaging system: when undisturbed, the imaging surface has uniform brightness; when a density gradient exists, the light is deflected, causing some light to be blocked by the blade, resulting in variations in image brightness, thus enabling the visualization of an invisible density field.

[0020] Existing ultrasonic field measurement schemes mainly include hydrophone scanning systems and 4f system schlieren imaging schemes.

[0021] The hydrophone 3D scanning system acquires spatial sound pressure distribution point by point by driving hydrophones with a motor. Its advantage is high measurement accuracy, but it has the following limitations: high-precision hydrophones are expensive; resolution is limited by the precision of mechanical control; 3D scanning takes tens of minutes to several hours and cannot capture the dynamic sound field of pulse ultrasound; the system is large in size and difficult to carry or deploy in confined spaces.

[0022] A schlieren imaging scheme based on a 4f system. This scheme uses two sets of convex lenses to form a 4f optical path, and places an aperture on the Fourier surface to filter out the DC component, achieving optical visualization of the acoustic field. Its limitations are: numerous optical components and complex optical path adjustment; high dependence on the stability of the optical platform, requiring lengthy calibration after movement; and high cost due to reliance on high-power lasers and high-precision lenses, making it difficult to achieve portability.

[0023] Existing ultrasonic field measurement or imaging systems each have their limitations. Hydrophone scanning sound field systems are simple in principle, but high-precision hydrophones are expensive, and their resolution is limited by the precision of motor and lead screw control. To ensure scanning accuracy and resolution, the system requires long scanning times, which is detrimental to capturing dynamic signals. However, the ultrasonic signals used for neuromodulation are often pulse signals, resulting in poor dynamic performance and an inability to capture the sound field. Furthermore, these systems are bulky and cannot be portable or deployed in confined spaces, thus limiting their application scenarios.

[0024] like Figure 1 As shown, the schlieren measurement device of the 4f system consists of two sets of convex lenses forming a 4f optical path. An aperture is placed on the Fourier surface to filter out the DC component, achieving optical visualization of the acoustic field. The disadvantages of this system are the large number of optical lens combinations, complex optical path adjustment, and high dependence on the stability of the optical platform, making it unportable and difficult to operate. Moving the system requires a lengthy optical calibration process, which is complex. Furthermore, the reliance on a high-power laser and high-precision lenses results in high system cost.

[0025] To address the shortcomings of the above solutions, this application utilizes a schlieren optical path system constructed from a single spherical mirror, which significantly reduces the size of the schlieren system, lowers operational complexity, and cuts costs. Simultaneously, combining the schlieren blade with the camera's adjustable aperture enhances the system's compactness. Furthermore, by adjusting the angle of the mirror and the optical path height, the reflected light image and the "shadow" problem in single-mirror schlieren systems are eliminated. This application offers high spatiotemporal resolution, effectively assisting in the acoustic field diagnosis and measurement of ultrasound neuromodulation systems.

[0026] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1 like Figure 2 As shown, this embodiment provides a holographic imaging system for evaluating ultrasound neuromodulation sound fields, including: LED light source 6, single spherical reflector 5, industrial camera 1 with adjustable aperture 1, water tank 3 for supporting ultrasonic transducer 7, lifting platform 4 and platform guide rail 8. The LED light source 6 and the industrial camera 1 are both mounted on the platform guide rail 8 and located on the same side of the single spherical reflector 5, forming a reflective schlieren light path. The LED light source 6 is positioned near the focal plane of the single spherical mirror 5, and the industrial camera 1 is positioned at the focal plane on the other side of the single spherical mirror 5. The water tank 3 is placed on top of the lifting platform 4 and is filled with distilled water. The transducer 7 is placed flat in the center of the bottom of the water tank 3 and is driven by a signal generator and a power amplifier to generate a pulsed ultrasonic field. The lifting platform 4 is used to adjust the height of the water tank 3 so that the single spherical reflector 5 is completely submerged in the water; The adjustable aperture of the industrial camera 1 serves as a schlieren blade, which performs spatial filtering on the converged light rays after reflection by the single spherical mirror 5 to form a schlieren image that reflects the density gradient distribution of the ultrasonic field.

[0028] In this embodiment, a small schlieren mirror combined with a reflective optical path design, along with the high spatiotemporal resolution of the schlieren system, is used to capture the transient establishment process of the sound field at the millisecond level and to verify the static sound field morphology.

[0029] Specifically, in some embodiments, the industrial camera 1 is equipped with an aperture, and its support has a 5-DOF adjustment function. Both the industrial camera 1 and the LED light source 6 can be adjusted forward and backward on the platform guide rail 8. The display 2 can be a computer or other processor, connected to the camera via a GigE interface, for displaying ultrasonic field images and performing processing and analysis. The water tank 3 is located in the groove at the top of the lifting platform 4, with clean walls and filled with distilled water. The transducer 7 is placed flat at the center of the bottom of the water tank. The transducer 7 is equipped with an acoustic metasurface, which can generate single-point and dual-point focused sound fields by changing the acoustic metasurface, and can also be designed to generate different ultrasonic fields as needed. The transducer 7 is driven by a signal generator and a power amplifier to generate a pulsed sound field in the water tank 3. The transducer 7 is equipped with acoustic metasurfaces, including single-point focusing metasurfaces, dual-point focusing metasurfaces, and single-sided single-point focusing metasurfaces.

[0030] Example 2 This embodiment provides a dynamic observation method based on the aforementioned holographic imaging system for evaluating ultrasound neuromodulation sound fields, including: S1. Connect the power supply to the industrial camera 1 and the monitor 2, and adjust the aperture of the industrial camera 1 to the minimum; lower the lifting platform 4 to the lowest position, and slowly raise the water tank 3 so that the single spherical mirror 5 is completely submerged in the water, and remove the air bubbles from the surface of the water tank 3 and the single spherical mirror 5. S2. Place the LED light source 6 at a set position on one side of the focal plane of the single spherical mirror 5, and place the industrial camera 1 at the focal plane on the other side to form a reflective schlieren light path; adjust the industrial camera 1 so that a bright spot appears in the display 2, and place its lower edge in the center of the display 2. S3. The transducer 7 is activated to generate a pulsed ultrasonic field. The light emitted by the LED light source 6 is deflected by the refractive index gradient inside the water tank 3. After being reflected by the single spherical mirror 5, it converges at the aperture position of the camera 1. After being filtered by the aperture, a schlieren image with light and dark distribution is formed on the camera image plane, which displays the spatial morphology and dynamic evolution process of the ultrasonic field in real time.

[0031] After executing step S3, the process also includes: S4: Establish a quantitative relationship model between schlieren image brightness and acoustic pressure gradient; based on the linear relationship between refractive index and medium density, combined with geometric optics, determine the proportional relationship between the change in schlieren image brightness and the integral of acoustic pressure gradient along the optical path; calibrate the holographic imaging system through single-point hydrophone measurement and determine the proportional coefficient.

[0032] Specifically, in some embodiments, when performing steps S1-S4, the specific steps may be as follows: 1) Initial setup of the device: Connect the power supply to industrial camera 1 and monitor 2, ensuring the indicator light on the industrial camera is lit, indicating normal operation. Adjust the camera aperture to the smallest possible setting. Lower the lifting platform 4 in front of the schlieren support to its lowest position, and slowly raise the water tank until the monospherical mirror 5 is completely submerged. If air bubbles appear on the surface of the water tank or the mirror, remove them promptly with a brush or similar tool.

[0033] 2) Optical path adjustment: The holographic imaging system uses a single spherical mirror to simultaneously collimate and focus light. An LED light source 6 is placed near the focal plane of the mirror, while the industrial camera 1 and its aperture are positioned at the focal plane on the other side of the mirror, forming a reflective schlieren light path. The industrial camera 1 is adjusted so that a bright spot is visible on the display 2, with the lower edge of the spot centered on the display. The transducer 7 is adjusted to generate an ultrasonic sound field from an acoustic metasurface. Light emitted from the LED light source 6 enters the water tank; the refractive index gradient caused by the sound field deflects the light, which is then reflected by the single-sided spherical mirror 5 and converges at the aperture position of the industrial camera 1. After filtering by the aperture, a schlieren image with varying brightness is formed on the camera's image plane, thus enabling visualization of the ultrasonic sound field.

[0034] After the above steps, the following schlieren image can be obtained by eliminating artifacts in the reflected light path. Furthermore, different acoustic metasurfaces can be used to observe different sound field images. Figure 3Images a)-d) in the image show the original holographic sound field schlieren images with different morphologies, using a single-point focusing metasurface, a double-point focusing metasurface, and a single-sided single-point focusing metasurface, respectively. The morphology of the holographic sound field in the image directly reflects the sound intensity distribution at various points in space.

[0035] 3) Determine the relationship between the output of the schlieren system and the sound field: First, determine the relationship between the refractive index gradient and the local pressure: the relationship between the refractive index and the density and polarizability of the medium can be known from Maxwell's equations.

[0036] ; in, Represents spatial location Time The refractive index at that time The relative permittivity at that location and time. The density at that location and time. The polarizability of the dielectric. The density is the density of the medium when it is static and undisturbed.

[0037] By utilizing the small amplitude and the minute pressure change induced by sound pressure in a water medium, we can obtain: ; in, For sound pressure level, The refractive index of the medium when it is undisturbed. The speed at which sound waves propagate in a medium. This represents the rate of change of refractive index with respect to pressure.

[0038] Therefore, with constant variables such as temperature and salinity, it can be seen that the refractive index of water changes linearly under small pressure changes.

[0039] Determine the relationship between local pressure and schlieren image brightness: The vector expression for the ray propagation equation in geometric optics is shown below: ; in, It is the tiny arc length along the path of light propagation; It is the position vector of a point on the ray; It is a location The refractive index at that point; The refractive index gradient; This is the total derivative along the ray path with respect to the arc length; It indicates the direction of light propagation.

[0040] Since this embodiment only considers the refractive index gradient change along the Z-axis, the vector equation can be simplified to the following form: ; This represents the component of the ray direction vector on the Z-axis. This represents the gradient of the refractive index of the medium along the Z-axis.

[0041] Due to the condition of perpendicular incidence, it can be known that , where ds represents the tiny displacement of the light ray during its propagation. Now, we integrate both sides of the partial differential equation from 0 to s, as follows: ; get: .

[0042] Since light rays do not bend along the x-axis, let the angle between the light ray and the y-axis be θ. Because the medium region is very small and the refractive index gradient changes continuously and uniformly in space, therefore It satisfies a small-angle approximation. The direction of light emission is: ; therefore: ; From the gradient relationship between the refractive index of the medium and the pressure, we can obtain: ; Therefore, the angle between the outgoing ray and the incident ray is obtained. It is proportional to the integral of the partial derivative of the pressure field along the z-axis over the optical path: .

[0043] In knife-edge schlieren systems, the occlusion of the light source's image by the blade plays a crucial role.

[0044] Assume the brightness of an undisturbed point on the schlieren image is The brightness after knife-edge filtering is So, if Figure 4 As shown, we have: ; Therefore, the brightness difference at the same point in the schlieren image before and after the perturbation can be expressed as: ; Once the locations of all system components are determined, then , Since and d are both constant values, the brightness difference between a point in the schlieren image and the background image satisfies: ; Where α is the direction of the outward normal of the blade edge.

[0045] Therefore, for a system that has been calibrated, the brightness difference between the schlieren image and the background image is directly proportional to the pressure change at that point. The simplest calibration method is to determine this coefficient by taking a single measurement with a hydrophone. For example, a single sound pressure measurement at the focal point of a single-point focused sound field can yield the corresponding proportionality coefficient. This allows for millisecond-level imaging speeds of holographic sound fields, meeting the need for rapid visualization of sound fields.

[0046] like Figure 5 As shown in the figure, (a) is the scanning result of a single-point focused sound field by the hydrophone, and (b) is the observation result of the schlieren method. As shown in the figure (c), by comparing the data of the sampling line, it can be seen that the measurement effect of the schlieren method matches well with that of the hydrophone, and the corresponding relationship of the sound intensity function of the system is established.

[0047] Therefore, this application proposes a compact schlieren optical path structure based on a single spherical mirror. By using a single spherical mirror instead of the multiple lens structures in the traditional 4f system, the light source collimation, sound field illumination and light focusing are achieved through a reflective optical path, which greatly reduces the system size, reduces the complexity of optical path adjustment, and enables portable deployment.

[0048] This application also proposes to integrate the schlieren blade edge with the adjustable optical path of the camera, integrating the blade edge filtering function of the traditional schlieren system into the adjustable aperture structure of the industrial camera, eliminating the need for an additional precision blade edge adjustment mechanism, simplifying the system structure, and improving adjustment efficiency and system stability. This application also proposes a coordinated adjustment mechanism for the height of the water tank and the optical path. By adjusting the height of the water tank through a lifting platform, the spherical mirror is completely immersed in the water. Combined with the mirror angle deflection and the fine adjustment of the optical path height, the problem of "shadow" artifacts in the water tank surface reflection image and the single-mirror schlieren system is effectively eliminated, thereby improving the imaging quality.

[0049] This application also proposes a quantitative relationship model between the sound field pressure gradient and the brightness of the schlieren image. Based on the linear relationship between the refractive index and the pressure gradient, and combined with geometric optics, the proportional relationship between the change in the brightness of the schlieren image and the integral of the sound field pressure gradient along the optical path is derived, providing a theoretical basis for the quantitative visualization of the sound field.

[0050] This application also proposes a real-time imaging capability for dynamic sound fields applicable to pulse signals. By utilizing the high temporal resolution (millisecond level) of the schlieren system and combining it with a high-brightness LED light source and an industrial camera, it achieves real-time capture of the transient establishment process and steady-state sound field morphology of the pulse sound field in ultrasonic neuromodulation, overcoming the defect that hydrophones cannot capture dynamic signals by scanning point by point.

[0051] Furthermore, in some other instances, the following alternatives exist in the prior art to achieve the goals of sound field visualization and verification of ultrasound neuromodulation systems: Three-dimensional scanning system for hydrophones: By driving hydrophones with motors to collect the spatial distribution of sound field point by point, it can achieve high-precision sound field measurement, but it has disadvantages such as long scanning time, inability to capture dynamic sound field, large system size, and high cost.

[0052] Schlieren imaging system based on 4f lens structure: It can realize optical visualization of sound field by forming a 4f optical path through two sets of convex lenses and performing spatial filtering on the Fourier surface. However, the optical path adjustment is complicated, it relies on a highly stable optical platform, the system has poor portability and high cost.

[0053] The aforementioned alternatives all have significant limitations in terms of dynamic imaging capabilities, system complexity, portability, and cost control. The single-spherical mirror schlieren system proposed in this application maintains high spatiotemporal resolution while significantly improving system integration and ease of operation, making it the preferred solution that balances imaging performance and engineering practicality.

[0054] In summary, this application has the following technical effects: 1) The system has a compact structure and is highly portable: This application uses a single spherical mirror to replace the traditional multi-lens group, which reduces the number of optical components and the size of the system. It can work stably without relying on a large optical platform and is easy to deploy flexibly in various environments such as laboratories and clinical sites.

[0055] 2) Simple optical path adjustment and low operating threshold: This application integrates the knife-edge function into the camera's adjustable aperture, and together with the lifting platform and mirror angle adjustment, significantly reduces the complexity of optical path calibration. No complex optical calibration process is required after system movement, exhibiting good repeatability and user-friendliness.

[0056] 3) Fast imaging speed, suitable for dynamic sound fields: Compared with the point-by-point scanning method of hydrophones (tens of minutes to several hours), this application can achieve real-time imaging of the whole field with millisecond-level time resolution by utilizing the schlieren imaging principle, which is particularly suitable for the visualization of transient sound fields of pulse signals in ultrasound neuromodulation.

[0057] 4) High imaging quality and strong artifact suppression capability: This application effectively suppresses the "shadow" artifacts in the water tank surface reflection image and the single-mirror schlieren system by adjusting the optical path height and deflecting the mirror angle, thereby obtaining a high-contrast, high-signal-to-noise ratio sound field image and improving the reliability of sound field verification.

[0058] 5) Low system cost and easy to promote: This application does not require high-power lasers, high-precision large-size lenses or precision mechanical scanning mechanisms. It adopts mature components such as LED light sources, industrial cameras and single spherical mirrors. The system manufacturing cost is significantly lower than that of commercial schlieren scanners and hydrophone scanning systems, and has good industrialization prospects.

[0059] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A holographic imaging system for evaluating ultrasonic neuromodulation sound fields, characterized in that, include: LED light source (6), single spherical reflector (5), industrial camera (1) with adjustable aperture, water tank (3) for carrying ultrasonic transducer (7), lifting platform (4) and platform guide rail (8); The LED light source (6) and the industrial camera (1) are both mounted on the platform guide rail (8) and located on the same side of the single spherical reflector (5) to form a reflective schlieren light path; The LED light source (6) is located near the focal plane of the single spherical mirror (5), and the industrial camera (1) is located on the other side of the focal plane of the single spherical mirror (5). The water tank (3) is placed on top of the lifting platform (4) and filled with distilled water. The transducer (7) is placed flat in the center of the bottom of the water tank (3) and is driven by the signal generator and power amplifier to generate a pulsed ultrasonic field. The lifting platform (4) is used to adjust the height of the water tank (3) so that the single spherical reflector (5) is completely submerged in the water; The adjustable aperture of the industrial camera (1) serves as the schlieren blade, which performs spatial filtering on the light rays that converge after being reflected by the single spherical mirror (5) to form a schlieren image that reflects the density gradient distribution of the ultrasonic field.

2. The holographic imaging system for evaluating ultrasound neuromodulation sound fields according to claim 1, characterized in that, The single spherical mirror (5) is used to simultaneously perform the functions of collimation and focusing of light.

3. The holographic imaging system for evaluating ultrasound neuromodulation sound fields according to claim 1, characterized in that, The bracket of the industrial camera (1) has a five-degree-of-freedom adjustment function, which is used to adjust the position and attitude of the camera; both the LED light source (6) and the industrial camera (1) can move on the platform guide rail (8).

4. The holographic imaging system for evaluating ultrasound neuromodulation sound fields according to claim 1, characterized in that, The transducer (7) is equipped with an acoustic metasurface, which includes a single-point focusing metasurface, a double-point focusing metasurface, and a single-sided single-point focusing metasurface.

5. The holographic imaging system for evaluating ultrasound neuromodulation sound fields according to claim 1, characterized in that, It also includes: a display (2), which is connected to an industrial camera (1) via a GigE interface for real-time display of ultrasonic field schlieren images and processing and analysis using a processor.

6. A dynamic observation method for a holographic imaging system for evaluating an ultrasound neuromodulation sound field according to any one of claims 1-5, characterized in that, include: S1. Connect the power supply of the industrial camera (1) and the monitor (2), and adjust the aperture of the industrial camera (1) to the minimum; lower the lifting platform (4) to the lowest position, and slowly raise the water tank (3) so that the single spherical mirror (5) is completely submerged in the water, and remove the air bubbles from the surface of the water tank (3) and the single spherical mirror (5). S2. Place the LED light source (6) at a set position on one side of the focal plane of the single spherical mirror (5), and place the industrial camera (1) at the focal plane on the other side to form a reflective schlieren light path; adjust the industrial camera (1) so that a bright spot appears in the display (2) and its lower edge is located in the center of the display (2). S3. Start the transducer (7) to generate a pulsed ultrasonic field. The light emitted by the LED light source (6) is deflected by the refractive index gradient inside the water tank (3). After being reflected by the single spherical mirror (5), it converges at the aperture position of the camera (1). After being filtered by the aperture, a schlieren image with light and dark distribution is formed on the camera image plane, and the spatial morphology and dynamic evolution process of the ultrasonic field are displayed in real time.

7. The dynamic observation method according to claim 6, characterized in that, Also includes: S4: Establish a quantitative relationship model between schlieren image brightness and acoustic pressure gradient; based on the linear relationship between refractive index and medium density, combined with geometric optics, determine the proportional relationship between the change in schlieren image brightness and the integral of acoustic pressure gradient along the optical path; calibrate the holographic imaging system through single-point hydrophone measurement and determine the proportional coefficient.

8. The dynamic observation method according to claim 7, characterized in that, The formula for the proportional relationship between the brightness change of the schlieren image and the integral of the sound field pressure gradient along the optical path is as follows: ； In the formula, The angle between the outgoing ray and the incident ray. It is the tiny arc length along the path of light propagation. Let be the position vector of a point on the ray; This represents the gradient of the sound field pressure along the Z-axis.

9. The dynamic observation method according to claim 6, characterized in that, S2 specifically includes: By adjusting the lifting platform (4), the single spherical mirror (5) is immersed in water, and by combining the mirror angle deflection and optical path height fine adjustment, the reflection image on the surface of the water tank (3) and the shadow artifacts in the holographic imaging system are eliminated.

10. The dynamic observation method according to claim 6, characterized in that, S3 specifically includes: By utilizing the millisecond-level temporal resolution of the schlieren system, combined with a high-brightness LED light source and an industrial camera, real-time capture of the transient establishment process and steady-state sound field morphology of the pulse sound field in ultrasonic neuromodulation can be achieved.

Images