A Reconfigurable Laser Ultrasonic Phased Array Device and Method

Abstract

A reconfigurable laser ultrasonic phased array method and device disclosed by the present invention belong to the technical field of ultrasonic phased arrays. The present invention includes a photo-thermoacoustic generation subsystem and a reconfigurable three-dimensional light field generation subsystem. The photo-thermoacoustic generation subsystem includes a MEMS photoacoustic transducer array, and the array unit is composed of a photoacoustic conversion layer, an isolation layer, and a support layer in the thickness direction. The reconfigurable three-dimensional light field generation subsystem includes a timing laser source, a delay line, a spatial light modulator, a microlens array, and a focusing imaging optical lens group. The present invention generates a reconfigurable three-dimensional light field with time dimension characteristics through the reconfigurable three-dimensional light field generation subsystem, and generates an ultrasonic signal with controllable wavefront direction and shape through the photo-thermoacoustic generation subsystem. The present invention has the technical advantages of reconfigurable light field and large array scale. By controlling the time dimension characteristics and space dimension characteristics of the three-dimensional light field, an ultrasonic phased array with adjustable array combination mode, focusing form, and scanning mode can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultrasonic phased array, and relates to a reconfigurable laser ultrasonic phased array device and method. Background Art

[0002] Traditional ultrasonic phased techniques use electronic methods to control the deflection, focusing, and scanning of sound beams, and can perform scanning without moving or with little movement of the transducer. Ultrasonic phased detection systems based on ultrasonic phased techniques are widely used in fields such as medical ultrasonic imaging and industrial non-destructive testing. The array types of existing ultrasonic phased array devices include linear arrays, circular arrays, and two-dimensional planar arrays. The array scale of two-dimensional planar ultrasonic phased array devices generally does not exceed 8×8; the focusing forms include linear array focusing, circular focusing, and two-dimensional array focusing; the scanning methods include sector scanning, linear scanning, and dynamic depth scanning. Existing ultrasonic phased array devices are generally non-reconfigurable and can only achieve ultrasonic phased scanning by adopting a single array composition method, focusing form, and scanning method.

[0003] Methods for realizing ultrasonic focusing by applying the photo-thermal-acoustic effect generally prepare a photoacoustic conversion layer on a spherical or conical substrate, and utilize the geometric focusing characteristics of the spherical or conical surface to achieve ultrasonic focusing, or utilize a patterned photoacoustic conversion layer to achieve spatial sound field focusing. The above ultrasonic focusing methods are difficult to achieve ultrasonic phased scanning. The method of using a multi-pump laser array to irradiate a photoacoustic transducer or a photoacoustic transducer array to achieve photoacoustic focusing can achieve ultrasonic phased scanning, but it also has the disadvantages of a small optical field array scale and non-reconfigurability. Summary of the Invention

[0004] The main object of the present invention is to provide a reconfigurable laser ultrasonic phased array device and method, which uses a reconfigurable three-dimensional light field with time dimension characteristics as an ultrasonic excitation source, uses a MEMS photoacoustic transducer array to receive the three-dimensional light field, generates ultrasonic signals with controllable wavefront direction and shape, and realizes a reconfigurable laser ultrasonic phased array with adjustable array combination method, focusing form, and scanning method.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] A reconfigurable laser ultrasonic phased array device disclosed by the present invention mainly consists of a reconfigurable three-dimensional light field generation subsystem and a photo-thermo-acoustic generation subsystem.

[0007] The reconfigurable three-dimensional light field generation subsystem includes a time-sequential laser source, a delay line, a spatial light modulator, a microlens array, and a focusing imaging optical lens group; the reconfigurable three-dimensional light field generation subsystem is used to generate a three-dimensional light field with time dimension characteristics; an initial optical delay signal is generated by the time-sequential laser source; a stepped optical delay signal with different time delays is generated by the delay line; the stepped optical delay signal is spatially modulated by the spatial light modulator to generate an isochronous line image; all the isochronous line images are superimposed into a composite image by the microlens array to generate a three-dimensional light field with time dimension characteristics; the three-dimensional light field with time dimension characteristics is projected onto the photoacoustic generation subsystem by the focusing imaging optical lens group.

[0008] The delay line can specifically be selected as an optical fiber delay line or a digital delay line. Preferably, an optical fiber delay line is adopted.

[0009] The spatial light modulator can specifically be selected as a liquid crystal (LCD) spatial light modulator, a digital micromirror device (DMD) spatial light modulator, or a liquid crystal on silicon (LCoS) spatial light modulator. Preferably, a digital micromirror device (DMD) spatial light modulator is adopted.

[0010] Preferably, the three-dimensional light field with time dimension characteristics refers to a three-dimensional light field with time dimension characteristics and two-dimensional spatial dimension characteristics.

[0011] Preferably, the reconfigurable three-dimensional light field generation subsystem controls the spatial dimension characteristics of the isochronous line image through the spatial light modulator to realize the control of the spatial dimension characteristics of the three-dimensional light field, and controls the stepped delay of the multiple stepped optical delay signals through the delay line to realize the control of the time dimension characteristics of the three-dimensional light field. The spatial dimension characteristics and time dimension characteristics of the three-dimensional light field determine the array composition mode, focusing form, and scanning mode of the laser ultrasonic phased array.

[0012] The photoacoustic generation subsystem includes a MEMS photoacoustic transducer array, and the array unit is composed of a photoacoustic conversion layer, an isolation layer, and a support layer in the thickness direction; the photoacoustic conversion layer is used to receive the reconfigurable three-dimensional light field with time dimension characteristics and generate an ultrasonic signal with controllable wavefront direction and shape; the isolation layer is used to suppress the heat transfer loss from the photoacoustic conversion layer to the substrate and improve the photoacoustic conversion efficiency; the support layer is used to provide mechanical support for the photoacoustic conversion layer and the isolation layer.

[0013] The photoacoustic conversion layer is composed of patterned metal nanomaterials. The metal nanomaterials can specifically be metal nanoaggregates prepared by evaporation deposition process and periodic metal nanomaterials prepared by magnetron sputtering process. Preferably, aluminum nanoaggregates prepared by evaporation deposition process are used. The isolation layer is composed of a patterned polymer thin film. The polymer thin film can specifically be a polyimide (PI) thin film and a polydimethylsiloxane (PDMS) thin film. Preferably, a polyimide thin film is used. The support layer is composed of a silicon wafer with a supporting microstructure. The supporting microstructure can specifically be a cavity-type supporting structure, a table-type supporting structure, and a column-type supporting structure. Preferably, a cavity-type supporting structure is used. The patterning of the photoacoustic conversion layer and the isolation layer is to reduce the mass and thermal inertia of the photoacoustic transducer array unit. The specific pattern shape does not affect the function realization of the photoacoustic transducer array unit. Therefore, the specific pattern shape should be regarded as a preference of the present invention.

[0014] Preferably, the MEMS photoacoustic transducer array has the characteristics of small array unit size and large array scale, and is used to completely receive the time dimension information and space dimension information of the three-dimensional light field. The large array scale means that the maximum array scale can reach 1280×1280. The small array unit size means that the minimum array unit size can reach 34μm×34μm.

[0015] Preferably, by controlling the time dimension characteristics and space dimension characteristics of the three-dimensional light field, a light source signal required for the photo-thermoacoustic phonon system is provided for the ultrasonic phased array.

[0016] Preferably, the adjustable array combination method means that the array type and array scale are adjustable.

[0017] A working method of a reconfigurable laser ultrasonic phased array device disclosed by the present invention is as follows:

[0018] Step 1: The reconfigurable three-dimensional light field generation subsystem generates an initial optical delay signal through a timing laser source.

[0019] Step 2: The initial optical delay signal is input into a delay device, and a plurality of stepped optical delay signals are generated through the delay device, and the stepped delay of the plurality of stepped optical delay signals is controlled.

[0020] Step 3: The plurality of stepped optical delay signals are input into a spatial light modulator, and the stepped optical delay signals are spatially modulated through the spatial light modulator to generate an isochronous line image.

[0021] Step 4: The equal-delay line images are input into the microlens array, and all the equal-delay line images are superimposed into a composite image through the integral imaging system of the microlens array to generate a three-dimensional light field with time-dimensional characteristics; the reconfigurable three-dimensional light field generation subsystem controls the spatial dimensional characteristics of the equal-delay line images through the spatial light modulator to realize the control of the spatial dimensional characteristics of the three-dimensional light field; the reconfigurable three-dimensional light field generation subsystem controls the step delay of the multi-channel stepped optical delay signals through the optical delay line to realize the control of the time-dimensional characteristics of the three-dimensional light field.

[0022] Step 5: The three-dimensional light field with time-dimensional characteristics is input into the focusing imaging optical lens group, and the three-dimensional light field with time-dimensional characteristics is projected onto the photo-thermoacoustic generation subsystem through the focusing imaging optical lens group.

[0023] Step 6: The photo-thermoacoustic generation subsystem receives the three-dimensional light field with time-dimensional characteristics through the MEMS photoacoustic transducer array to generate an ultrasonic signal with controllable wavefront direction and shape, realizing a reconfigurable laser ultrasonic phased array with adjustable array combination mode, focusing form, and scanning mode.

[0024] Beneficial effects:

[0025] 1. Generally, existing ultrasonic phased array devices are non-reconfigurable and can only perform ultrasonic phased scanning in a single array type, focusing form, and scanning mode. A reconfigurable laser ultrasonic phased array device and method disclosed by the present invention use a reconfigurable three-dimensional light field generation subsystem to generate a reconfigurable three-dimensional light field with time-dimensional characteristics as an ultrasonic excitation light source, and use a MEMS photoacoustic transducer array to receive the three-dimensional light field to generate an ultrasonic signal with controllable wavefront direction and shape, capable of realizing a reconfigurable laser ultrasonic phased array with adjustable array combination mode, focusing form, and scanning mode.

[0026] 2. Generally, existing laser ultrasonic phased array devices use a multi-pump laser array as an ultrasonic excitation source, and the scale of the laser array does not exceed a 10×10 planar array, and the cost is relatively high. A reconfigurable laser ultrasonic phased array device and method disclosed by the present invention generate an initial optical delay signal through a sequential laser source; generate stepped optical delay signals with different time delays through an optical delay line; perform spatial modulation on the stepped optical delay signals through a spatial light modulator to generate equal-delay line images; and superimpose all the equal-delay line images into a composite image through a microlens array to generate a three-dimensional light field with time-dimensional characteristics. The three-dimensional light field can achieve a 76×76 planar array scale, which is much higher than the light field planar array scale generated by the prior art, and the cost is relatively low. Description of the Drawings

[0027] Figure 1 It is a schematic block diagram of a reconfigurable laser ultrasonic phased array device according to an embodiment of the present invention.

[0028] Figure 2 Schematic diagram of the working process of a reconfigurable laser ultrasonic phased array device according to an embodiment of the present invention;

[0029] Figure 3 Schematic diagram of the MEMS photoacoustic transducer array structure according to an embodiment of the present invention;

[0030] Figure 4 Schematic diagram of a reconfigurable laser ultrasonic phased array device and method according to an embodiment of the present invention for generating an ultrasonic signal with a controllable wavefront direction;

[0031] Figure 5 Schematic diagram of a reconfigurable laser ultrasonic phased array device and method according to an embodiment of the present invention for generating an ultrasonic signal with a controllable wavefront shape;

[0032] Figure 6 Schematic diagram of a reconfigurable laser ultrasonic phased array device and method according to an embodiment of the present invention for realizing acoustic beam focusing. Detailed implementation manners

[0033] In order to better illustrate the purpose and advantages of the present invention, the following further describes the content of the invention with reference to the drawings and examples.

[0034] Combined with Figure 1 、 Figure 2 and Figure 3 As shown, a reconfigurable laser ultrasonic phased array device disclosed in this embodiment is composed of a reconfigurable three-dimensional light field generation subsystem and a photo-thermoacoustic sound generation subsystem.

[0035] The reconfigurable three-dimensional light field generation subsystem includes a time-sequential laser source, an optical fiber delay line, a digital micromirror device (DMD) spatial light modulator, a microlens array, and a focusing imaging optical lens group; the reconfigurable three-dimensional light field generation subsystem is used to generate a three-dimensional light field containing time dimension characteristics; an initial optical delay signal is generated by the time-sequential laser source; a stepped optical delay signal with different time delays is generated by the optical fiber delay line; the stepped optical delay signal is spatially modulated by the digital micromirror device (DMD) spatial light modulator to generate an isochronous line image; all the isochronous line images are superimposed into a composite image by the microlens array to generate a reconfigurable three-dimensional light field with time dimension characteristics; the reconfigurable three-dimensional light field with time dimension characteristics is projected onto the photo-thermoacoustic sound generation subsystem by the focusing imaging optical lens group.

[0036] The photo-thermoacoustic phonon subsystem includes a MEMS photoacoustic transducer array. Each array unit consists of three layers in the thickness direction, namely a photoacoustic conversion layer, an isolation layer, and a support layer. The photoacoustic conversion layer is composed of patterned aluminum nano-aggregated materials, which is used to receive a reconfigurable three-dimensional light field with time-dimensional characteristics and generate ultrasonic signals with controllable wavefront direction and shape. The isolation layer is composed of patterned polyimide films, which is used to suppress the heat transfer loss from the photoacoustic conversion layer to the substrate and improve the photoacoustic conversion efficiency. The support layer is composed of a silicon wafer with supporting microstructures, which is used to provide mechanical support for the photoacoustic conversion layer and the isolation layer.

[0037] The reconfigurable three-dimensional light field generation subsystem controls the spatial dimensional characteristics of the isochronous line image through a spatial light modulator to achieve the control of the spatial dimensional characteristics of the three-dimensional light field, and controls the step delay of the multi-channel stepped optical delay signals through a delay device to achieve the control of the time dimensional characteristics of the three-dimensional light field. The spatial dimensional characteristics and time dimensional characteristics of the three-dimensional light field determine the array composition method, focusing form, and scanning method of the laser ultrasonic phased array.

[0038] Combined Figure 1 、 Figure 2 and Figure 3 As shown in, a working method of a reconfigurable laser ultrasonic phased array device disclosed in this embodiment is as follows:

[0039] Step 1: The timing laser source generates an initial optical delay signal with a modulation frequency of 20 MHz through a 532 nm continuous laser and an intensity modulation signal generator.

[0040] Step 2: The initial optical delay signal is input into the delay device. The delay device generates multi-channel stepped optical delay signals with different time delays through multi-channel unequal-length delay optical fibers, and controls the delay step of the stepped optical delay signals through the length of the delay optical fibers. The stepped optical delay signals are output in the form of a 10×10 optical delay signal array.

[0041] Step 3: The multi-channel stepped optical delay signals are input into the spatial light modulator through a total reflection prism. The spatial light modulator adopts a digital micromirror device (DMD) spatial light modulator. The pixel scale of the spatial light modulator is 1920×1080, and the plane of the spatial light modulator is divided into a 10×10 array to receive 10×10 stepped optical delay signals with different time delays. Each spatial light modulator array region contains 108×108 pixels, and 76×76 pixels in the middle position are used to generate an isochronous line image, and the pixel size is 10.8 μm×10.8 μm.

[0042] Step 4: The isochronous line image is input into the microlens array. The microlens array is made of COC-480R material and contains 10×10 square microlenses, and the focal length of each microlens is f 1= 50 mm. The integrated imaging system with a microlens array superimposes all isochronous line images into a composite image, generating a three-dimensional light field with temporal dimension characteristics. The reconfigurable three-dimensional light field generation subsystem controls the spatial dimension characteristics of the isochronous line images through a spatial light modulator, thereby controlling the spatial dimension characteristics of the three-dimensional light field. The step delay of the multi-channel stepped optical delay signal is controlled through a delay line to control the temporal dimension characteristics of the three-dimensional light field. The spatial and temporal dimension characteristics of the three-dimensional light field determine the array composition, focusing form, and scanning method of the laser ultrasonic phased array;

[0043] Step Five: The three-dimensional light field with temporal dimension characteristics is input into the focusing imaging optical lens group. The focusing imaging optical lens group projects the three-dimensional light field with temporal dimension characteristics onto the photo-thermoacoustic generation subsystem. The focusing imaging optical lens group is made of BK7 material, and the focal length f 2 = 500 mm. The image size of a single spatial light modulator pixel projected onto the image plane of the photo-thermoacoustic generation subsystem is 108 μm × 108 μm, and the total image size of the three-dimensional light field projected onto the image plane of the photo-thermoacoustic generation subsystem is 8.2 mm × 8.2 mm;

[0044] Step Six: The photo-thermoacoustic generation subsystem receives the three-dimensional light field with temporal dimension characteristics through the MEMS photoacoustic transducer array, generating ultrasonic signals with controllable wavefront direction and shape. The scale of the MEMS photoacoustic transducer array is 1280 × 1280, and the array unit size is 36 μm × 36 μm, that is, the size of the MEMS photoacoustic transducer array is 46.08 mm × 46.08 mm; the image size of a single spatial light modulator pixel projected onto the image plane of the photo-thermoacoustic generation subsystem is 108 μm × 108 μm, which is more than 3 times the size of the MEMS photoacoustic transducer array unit. That is, the projected laser signal of each spatial light modulator pixel is received by 3 × 3 MEMS photoacoustic transducer array units. Therefore, this MEMS photoacoustic transducer array can completely receive the temporal and spatial dimension information of the three-dimensional light field.

[0045] Combined with Figure 4 As shown, a reconfigurable laser ultrasonic phased array device disclosed in this embodiment generates ultrasonic signals with controllable wavefront direction by controlling the temporal and spatial dimension characteristics of the three-dimensional light field. In this embodiment, 7-channel stepped optical delay signals are used, with a delay step of 12.5 ns and a wavefront direction deflection of 10°. By adjusting the shape of the isochronous line image and the signal delay, the control of the wavefront direction deflection angle can be achieved. Increasing the number of delay signals can improve the resolution of the wavefront direction deflection angle.

[0046] Combined with Figure 5As shown, a reconfigurable laser ultrasonic phased array device disclosed in this embodiment generates ultrasonic signals with a controllable wavefront shape by controlling the temporal dimension characteristics and spatial dimension characteristics of a three-dimensional light field. In this embodiment, 7 stepped optical delay signals are used, with signal delays of 20 ns, 15 ns, 10 ns, 5 ns, 0, 40 ns, and 60 ns respectively. The wavefront is an obtuse angle of 155°, and the wavefront direction deflects by 7.5°. By adjusting the shape of the equal-delay line image and the signal delay, the control of the wavefront shape can be achieved, and increasing the number of delay signals can improve the spatial resolution of the wavefront shape.

[0047] Combined with Figure 6 As shown, a reconfigurable laser ultrasonic phased array device disclosed in this embodiment generates ultrasonic signals with a controllable wavefront shape by controlling the temporal dimension characteristics and spatial dimension characteristics of a three-dimensional light field, realizes the focusing of ultrasonic signals, and can control the focal length and focusing direction by adjusting the shape of the equal-delay line image and the signal delay.

[0048] The above specific description further details the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above is only a specific embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A reconfigurable laser ultrasonic phased array device, characterized in that: it mainly consists of a reconfigurable three-dimensional light field generation subsystem and a photo-thermo-acoustic generation subsystem; The reconfigurable three-dimensional light field generation subsystem includes a time-sequential laser source, a delay line, a spatial light modulator, a microlens array, and a focusing imaging optical lens group; the reconfigurable three-dimensional light field generation subsystem is used to generate a three-dimensional light field containing time dimension characteristics; an initial optical delay signal is generated by the time-sequential laser source; a stepped optical delay signal with different time delays is generated by the delay line; the stepped optical delay signal is spatially modulated by the spatial light modulator to generate an isochronous line image; all the isochronous line images are superimposed into a composite image by the microlens array to generate a three-dimensional light field with time dimension characteristics; the three-dimensional light field with time dimension characteristics is projected onto the photo-thermo-acoustic generation subsystem by the focusing imaging optical lens group; The photo-thermo-acoustic generation subsystem includes a MEMS photoacoustic transducer array, and the array unit consists of three layers in the thickness direction, namely a photoacoustic conversion layer, an isolation layer, and a support layer; the photoacoustic conversion layer is used to receive the reconfigurable three-dimensional light field with time dimension characteristics and generate an ultrasonic signal with controllable wavefront direction and shape; the isolation layer is used to suppress the heat transfer loss from the photoacoustic conversion layer to the substrate and improve the photoacoustic conversion efficiency; the support layer is used to provide mechanical support for the photoacoustic conversion layer and the isolation layer.

2. A reconfigurable laser ultrasonic phased array device according to claim 1, characterized in that: The MEMS photoacoustic transducer array has the characteristics of small array unit size and large array scale, and is used to completely receive the time dimension information and spatial dimension information of the three-dimensional light field; the large array scale means that the maximum array scale reaches 1280×1280; the small array unit size means that the minimum array unit size reaches 34μm×34μm.

3. A reconfigurable laser ultrasonic phased array device according to claim 2, characterized in that: The photoacoustic conversion layer is composed of patterned metal nanomaterials, and the metal nanomaterials can specifically be metal nano-aggregation materials prepared by evaporation deposition process and periodic metal nanomaterials prepared by magnetron sputtering process; The isolation layer is composed of a patterned polymer thin film, and the polymer thin film can specifically be a polyimide PI thin film and a polydimethylsiloxane PDMS thin film; the support layer is composed of a silicon wafer with a support microstructure, and the support microstructure can specifically be a cavity support structure, a mesa support structure, and a column support structure; the patterning of the photoacoustic conversion layer and the isolation layer is to reduce the mass and thermal inertia of the photoacoustic transducer array unit, and the specific pattern shape does not affect the function realization of the photoacoustic transducer array unit.

4. A reconfigurable laser ultrasonic phased array device according to claim 3, characterized in that: Preferably, the metal nanomaterials are aluminum nano-aggregation materials prepared by evaporation deposition process; The isolation layer uses a polyimide thin film; The support layer uses a cavity support structure.

5. A reconfigurable laser ultrasonic phased array device according to claim 2, characterized in that: The delay device selects an optical fiber delay device or a digital delay device.

6. A reconfigurable laser ultrasonic phased array device as described in claim 2, characterized in that: The spatial light modulator selects a liquid crystal LCD spatial light modulator, a digital micromirror array DMD spatial light modulator or a liquid crystal on silicon LCoS spatial light modulator.

7. A reconfigurable laser ultrasonic phased array device as described in claim 2, characterized in that: The three-dimensional light field with time dimension characteristics refers to a three-dimensional light field with time dimension characteristics and two-dimensional spatial dimension characteristics.

8. A reconfigurable laser ultrasonic phased array device as described in claim 2, characterized in that: The reconfigurable three-dimensional light field generation subsystem controls the spatial dimension characteristics of the isochronous line image through the spatial light modulator to realize the control of the spatial dimension characteristics of the three-dimensional light field, and controls the step delay of the multiple-channel stepped optical delay signal through the delay device to realize the control of the time dimension characteristics of the three-dimensional light field. The spatial dimension characteristics and time dimension characteristics of the three-dimensional light field determine the array composition mode, focusing form and scanning mode of the laser ultrasonic phased array.

9. A reconfigurable laser ultrasonic phased array device as described in claim 2, characterized in that: By controlling the time dimension characteristics and spatial dimension characteristics of the three-dimensional light field, a light source signal required for the ultrasonic phased array is provided for the photo-thermoacoustic generation subsystem.

10. A working method of a reconfigurable laser ultrasonic phased array device, implemented based on a reconfigurable laser ultrasonic phased array device as described in claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, characterized in that: It includes the following steps, Step 1: The reconfigurable three-dimensional light field generation subsystem generates an initial optical delay signal through a timing laser source; Step 2: The initial optical delay signal is transmitted into the delay device, and multiple-channel stepped optical delay signals are generated through the delay device, and the step delay of the multiple-channel stepped optical delay signals is controlled; Step 3: The multiple-channel stepped optical delay signals are transmitted into the spatial light modulator, and the stepped optical delay signals are spatially modulated through the spatial light modulator to generate an isochronous line image; Step 4: The isochronous line image is transmitted into the microlens array, and all the isochronous line images are superimposed into a composite image through the integrated imaging system of the microlens array to generate a three-dimensional light field with time dimension characteristics; the reconfigurable three-dimensional light field generation subsystem controls the spatial dimension characteristics of the isochronous line image through the spatial light modulator to realize the control of the spatial dimension characteristics of the three-dimensional light field; the reconfigurable three-dimensional light field generation subsystem controls the step delay of the multiple-channel stepped optical delay signals through the delay device to realize the control of the time dimension characteristics of the three-dimensional light field; Step 5: The three-dimensional light field with time dimension characteristics is transmitted into the focusing imaging optical lens group, and the three-dimensional light field with time dimension characteristics is projected onto the photo-thermoacoustic generation subsystem through the focusing imaging optical lens group; Step 6: The photo-thermoacoustic generation subsystem receives the three-dimensional light field with time dimension characteristics through the MEMS photoacoustic transducer array, generates an ultrasonic wave signal with a controllable wavefront direction and shape, and realizes a reconfigurable laser ultrasonic phased array with an adjustable array combination mode, focusing form and scanning mode.

Images