A laser-ultrasound imaging device based on a micro-ring structure of a SIN chip

Abstract

The application discloses a kind of based on SIN chip micro-ring structure's laser ultrasonic imaging device, belong to laser ultrasonic imaging technical field, can solve the problems such as the detection device in existing laser ultrasonic imaging technology cannot bear high laser energy, detection sensitivity is not high, structural stability is insufficient, integrated degree is low etc..The device includes: laser emission module, SIN chip detection module, signal processing module and imaging module;Laser emission module is used to generate laser, and laser is focused to the surface of the target to be detected;Micro-ring waveguide in SIN chip detection module is connected with input waveguide and output waveguide respectively by coupling waveguide, and output modulated optical signal;Signal processing module is used to process optical signal obtained by SIN chip detection module into ultrasonic signal characteristic parameter;Imaging module is used to reconstruct image of the target to be detected according to ultrasonic signal characteristic parameter obtained by signal processing module.

Description

Technical Field

[0001] This invention relates to a high laser energy-bearing laser ultrasound imaging device with a SIN chip microring structure, belonging to the field of laser ultrasound imaging technology. Background Technology

[0002] Laser ultrasound imaging technology generates ultrasonic waves by irradiating the object under test with a laser. After being received and processed by a detection device, the internal structure of the object is imaged, and it has broad application prospects in many fields. Traditional ultrasonic detection devices mainly include piezoelectric sensors and optical interferometers. However, piezoelectric sensors are limited by special environments such as high temperature, high pressure, and toxicity, and may interfere with the object under test; optical interferometers are sensitive to environmental vibrations, lack stability, and are large in size and cost, which is not conducive to miniaturization and integration. Therefore, chip-based ultrasonic detection technology is gradually becoming a key technology in the field of laser ultrasound imaging.

[0003] Current chip-based ultrasonic detection technologies are mainly divided into capacitive and piezoelectric types. Capacitive transducers rely on a microcavity formed by a silicon-based diaphragm and electrodes, using capacitance changes to transmit and receive ultrasonic signals. Piezoelectric transducers, on the other hand, deposit piezoelectric thin films on a semiconductor substrate, utilizing the piezoelectric effect to convert electrical signals into ultrasonic signals. This technology typically arranges transducer units in an array to form an independently addressable detection array, coupled with on-chip integrated CMOS signal processing circuitry to acquire, condition, amplify, and perform preliminary processing of ultrasonic signals. Some solutions utilize electronic beamforming technology to focus and scan ultrasonic signals.

[0004] However, existing chip-based ultrasonic detection devices generally cannot withstand high laser energy, which would cause the chip temperature to become too high and thus damage the structural stability. Some simple-structured chips have low sensitivity to ultrasonic vibrations, making it difficult to accurately capture weak ultrasonic signals, resulting in low resolution and contrast. Some complex-structured chips have high detection sensitivity, but their manufacturing process is complex and the cost remains high. Overly thick chips will result in poor thermal conductivity, making it difficult to dissipate heat under high laser energy irradiation, which can easily cause damage due to heat accumulation. On the other hand, overly thin chips may not be able to guarantee structural stability and sufficient mechanical strength. Summary of the Invention

[0005] This invention provides a laser ultrasound imaging device based on a SIN chip microring structure, which can solve the problems of existing laser ultrasound imaging technology, such as the inability to withstand high laser energy, low detection sensitivity, insufficient structural stability, and low integration.

[0006] The present invention provides a laser ultrasound imaging device based on a SIN chip microring structure, comprising: a laser emission module, a SIN chip detection module, a signal processing module, and an imaging module; The laser emitting module is used to generate laser light and focus the laser light onto the surface of the target to be detected. The SIN chip detection module includes a SIN chip substrate and a micro-ring waveguide integrated on the SIN chip substrate; the micro-ring waveguide is connected to the input waveguide and the output waveguide respectively through coupling waveguides; The input waveguide is used to receive the probe laser; the micro-ring waveguide is used to resonantly modulate the probe laser; and the output waveguide is used to output the optical signal modulated by the micro-ring waveguide to the signal processing module. The signal processing module is used to process the optical signal obtained by the SIN chip detection module into ultrasonic signal characteristic parameters; The imaging module is used to reconstruct the image of the target to be detected based on the ultrasonic signal feature parameters obtained by the signal processing module.

[0007] The microring waveguide is circular with an inner diameter of 5μm-10μm, an outer diameter of 6μm-11μm, and a waveguide width of 500nm-800nm.

[0008] The thickness of the SIN chip substrate is 200nm-800nm.

[0009] Furthermore, the detection laser has a different wavelength than the laser emitted by the laser emitting module.

[0010] The laser emitting module includes a laser, a beam shaping assembly, and an optical path steering assembly; The laser is used to generate laser light; The beam shaping component is used to shape the laser generated by the laser into a parallel beam with a diameter of 100μm - 500μm; A light path steering assembly is used to focus the parallel light beam onto the surface of the target to be detected.

[0011] The signal processing module includes a photodetector, a preamplifier, a data acquisition card, and an FPGA processing unit. The photodetector is used to receive the optical signal output from the SIN chip detection module and convert it into an electrical signal; The preamplifier is used to amplify and denoise the electrical signal; The data acquisition card is used to sample the signal processed by the preamplifier and convert it into a digital signal; The FPGA processing unit is used to process the digital signal to obtain ultrasonic signal characteristic parameters.

[0012] Furthermore, the imaging module is specifically used to reconstruct the internal structure image of the target to be detected using an inversion algorithm to obtain a reconstructed image.

[0013] The reconstructed image is any one of two-dimensional tomography, planar imaging, or 3D imaging.

[0014] The beneficial effects of this invention include: the laser ultrasonic imaging device provided in this embodiment, due to the integrated design of the micro-ring waveguide and the SIN chip substrate, reduces external connecting components, which not only reduces signal loss and interference, but also reduces the overall system volume by more than 50%, making it easy to integrate with other modules. This meets the miniaturization and integration requirements of portable detection equipment, improving the practicality and convenience of the device. Furthermore, the 800nm ​​SIN chip substrate can withstand high laser energy, ensuring the structural stability of the laser ultrasonic imaging device under high energy impact, effectively solving the problem of heat accumulation under high laser energy. Compared with existing similar chips, the withstand capability is improved by more than 50%, enabling it to adapt to complex scenarios such as deep material detection and high-energy laser excitation, greatly expanding the application range of laser ultrasonic imaging technology. Furthermore, the high quality factor characteristics of the micro-ring waveguide make it extremely sensitive to minute changes in refractive index, achieving high-precision detection of nanometer-level vibration resolution. Compared to traditional planar thin-film structures, the detection sensitivity is increased by 3 to 5 times, enabling precise capture of weak ultrasonic echo signals and significantly improving imaging contrast and detail resolution. This provides a strong guarantee for obtaining high-quality detection images and can be widely used in industrial inspection, medical diagnosis and other fields. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a laser ultrasound imaging device based on a SIN chip microring structure, provided as an embodiment of the present invention. Detailed Implementation

[0016] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0017] See Figure 1 The present invention provides a laser ultrasound imaging device based on a SIN chip microring structure, comprising: a laser emission module 11, a SIN chip detection module 12, a signal processing module 13, and an imaging module 14; The laser emitting module 11 is used to generate laser light and focus the generated laser light onto the surface of the target to be detected; Specifically, the laser emitting module 11 includes a laser, a beam shaping assembly, and an optical path steering assembly.

[0018] In this embodiment of the invention, the laser is used to generate high-energy laser light, such as a Q-switched Nd:YAG laser with an output wavelength of 1064 nm. The output energy of the laser can be flexibly controlled by adjusting the Q-switching frequency, and the maximum energy density can reach 100 mJ / cm², which can meet the detection requirements of materials at different depths. This embodiment of the invention does not limit the specific model of the laser.

[0019] The beam shaping assembly is used to shape the laser generated by the laser into a parallel beam with a diameter of 100μm-500μm. In practical applications, the beam shaping assembly generally consists of a beam expander and a focusing lens. Since the beam shaping assembly is prior art, it will not be described in detail in this embodiment of the invention.

[0020] The optical path steering component is used to focus the parallel beam, after being shaped by the beam shaping component, onto the surface of the target to be detected, forming a local high-temperature region, thereby exciting ultrasonic waves.

[0021] The SIN chip detection module 12 includes a SIN chip substrate and a micro-ring waveguide integrated on the SIN chip substrate; the micro-ring waveguide is connected to the input waveguide and the output waveguide respectively through a coupling waveguide; The input waveguide is used to receive the probe laser. In practical applications, in order to avoid interference with the laser emitted by the laser emitting module, a probe laser with a different wavelength than the laser emitted by the laser emitting module can be selected, such as a 1550nm communication band laser.

[0022] The micro-ring waveguide is used to resonantly modulate the probe laser; The output waveguide is used to output the optical signal modulated by the micro-ring waveguide to the signal processing module 13. The present invention selects SiN (silicon nitride) as the chip substrate because SiN material has excellent mechanical properties. Its high elastic modulus and high strength can ensure the structural stability of the chip under high laser energy impact. At the same time, SiN material has good thermal stability, is resistant to high temperature and has a low thermal conductivity. When effectively combined with a heat dissipation substrate (such as a silicon substrate), it can quickly dissipate the heat generated by laser energy, ensuring that under high laser energy irradiation (energy density ≤150mJ / cm²), the heat accumulation generated by high laser energy is effectively suppressed, so that the chip structure is stable and the performance is not significantly degraded.

[0023] The thickness of a SIN chip substrate is typically 200nm-800nm. In this embodiment of the invention, the SIN chip substrate thickness is precisely set to 800nm. Extensive simulations and experiments have verified that this thickness ensures the SIN chip substrate possesses sufficient mechanical strength to prevent structural damage due to excessive thinness; it also allows for rapid heat dissipation through a rationally designed heat conduction path, significantly improving the chip's ability to withstand high laser energy. Compared to existing similar chips, its laser energy tolerance threshold is increased by more than 30%.

[0024] In this embodiment of the invention, micro-ring waveguides are fabricated on a SiN chip substrate using microelectronic processing techniques such as photolithography, etching, and thin film deposition, integrating the SiN chip substrate and the micro-ring waveguides into a single unit. The micro-ring waveguide is made of the same material as the chip substrate, SiN, and leverages the high refractive index of SiN (approximately 2.0) to achieve efficient confinement and transmission of optical signals within the micro-ring waveguide.

[0025] Because microring waveguides possess a high quality factor (Q value), they are extremely sensitive to minute changes in refractive index. Under ultrasonic vibration, the refractive index of the medium surrounding the microring changes. The microring waveguide can convert this refractive index change into a detectable optical signal change through its own optical resonance characteristics, thereby significantly improving ultrasonic detection sensitivity. In this embodiment of the invention, the microring waveguide is circular, with an inner diameter of 5μm-10μm, an outer diameter of 6μm-11μm, and a waveguide width of 500nm-800nm. In practical applications, the optical resonance performance of the microring waveguide can be optimized to make it more sensitive to ultrasonic signals in specific frequency bands, thereby achieving high-precision detection of weak ultrasonic signals, with detection accuracy reaching nanometer-level vibration resolution.

[0026] In this embodiment of the invention, the micro-ring waveguide is directly fabricated on the SIN chip substrate, achieving a high degree of integration between the detection structure and the chip. This integrated design reduces external connecting components, effectively lowering signal loss and interference during transmission, while significantly reducing the device size, facilitating integration with laser emission modules, signal processing modules, and other components into a miniaturized system. Compared to existing split structures, the integrated design of this invention reduces the overall system size by more than 50% and improves signal transmission efficiency by 20%, meeting the miniaturization and efficiency requirements of portable detection scenarios.

[0027] The signal processing module 13 is used to process the optical signal obtained by the SIN chip detection module 12 into ultrasonic signal characteristic parameters; Specifically, the signal processing module 13 includes a photodetector, a preamplifier, a data acquisition card, and an FPGA processing unit; The photodetector is used to receive the optical signal output from the SIN chip detection module 12 and convert it into an electrical signal; in practical applications, a balanced photodetector with a response bandwidth ≥ 1 GHz can be selected.

[0028] A preamplifier is used to amplify and denoise the electrical signal; in practical applications, the preamplifier gain can be flexibly adjusted within the range of 20dB to 60dB.

[0029] A data acquisition card with a sampling rate of ≥1GS / s is used to sample the signal processed by the preamplifier and convert it into a digital signal; The FPGA processing unit is used to process the digital signal to obtain ultrasonic signal characteristic parameters.

[0030] In practical applications, the FPGA processing unit processes digital signals by using bandpass filtering to remove low-frequency noise and high-frequency interference, extracting the amplitude information of ultrasonic signals through envelope detection, and identifying characteristic parameters of ultrasonic signals such as peak value and time of arrival.

[0031] The imaging module 14 is used to reconstruct the image of the target to be detected based on the ultrasonic signal feature parameters obtained by the signal processing module 13.

[0032] Specifically, after receiving the characteristic parameters of the ultrasonic signal, the imaging module 14 uses an inversion algorithm to reconstruct the internal structure image of the target to be detected, thus obtaining a reconstructed image. In practical applications, the inversion algorithm can choose synthetic aperture focusing technology, and the specific imaging mode can be selected according to the actual detection requirements, such as B-scan (two-dimensional tomography), C-scan (planar imaging), or 3D imaging, with an image resolution of 10μm-50μm.

[0033] The workflow of the laser ultrasonic imaging device based on the SIN chip microring structure provided in this embodiment of the invention is as follows: The laser emitting module 11 emits a high-energy laser, which, after focusing, irradiates the surface of the target to be detected. The laser energy is absorbed by the surface of the target to be detected, and ultrasonic waves are excited through thermoelastic or plasma effects, propagating into the interior of the target to be detected. When the ultrasonic waves propagate to defects or interfaces inside the target to be detected, reflection, refraction, or scattering occurs, and some of the reflected waves return to the surface, causing minute vibrations on the surface (the amplitude is usually in the nanometer range).

[0034] In the SIN chip detection module 12, the optical resonance characteristics of the micro-ring waveguide change due to the refractive index change of the surrounding medium caused by the vibration of the target surface, resulting in a shift in the resonant wavelength of the micro-ring waveguide. At this time, the detection laser input to the micro-ring waveguide, after resonant modulation, outputs a light intensity that changes accordingly with the resonant wavelength shift. This changed optical signal is captured by the photodetector and converted into an electrical signal. The electrical signal is then amplified, sampled, and processed sequentially by the signal processing module 13 to obtain digital information reflecting the characteristics of the ultrasonic signal. Finally, the imaging module 14 reconstructs the internal structure image of the object being detected using an imaging algorithm based on this digital information, thus completing the detection process.

[0035] The laser ultrasonic imaging device provided in this invention, due to the integrated design of the micro-ring waveguide and the SIN chip substrate, reduces external connecting components, which not only reduces signal loss and interference but also reduces the overall system volume by more than 50%, making it easy to integrate with other modules. This meets the miniaturization and integration requirements of portable detection devices, improving the practicality and convenience of the device. Furthermore, the 800nm ​​SIN chip substrate can withstand high laser energy, ensuring the structural stability of the laser ultrasonic imaging device under high-energy impact, effectively solving the problem of heat accumulation under high laser energy. Compared with existing similar chips, the withstand capability is improved by more than 50%, enabling it to adapt to complex scenarios such as deep material detection and high-energy laser excitation, greatly expanding the application range of laser ultrasonic imaging technology. Furthermore, the high quality factor characteristics of the micro-ring waveguide make it extremely sensitive to minute changes in refractive index, achieving high-precision detection of nanometer-level vibration resolution. Compared to traditional planar thin-film structures, the detection sensitivity is increased by 3 to 5 times, enabling precise capture of weak ultrasonic echo signals and significantly improving imaging contrast and detail resolution. This provides a strong guarantee for obtaining high-quality detection images and can be widely used in industrial inspection, medical diagnosis and other fields.

[0036] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A laser ultrasound imaging device based on a SIN chip microring structure, characterized in that, The device includes: a laser emission module, a SIN chip detection module, a signal processing module, and an imaging module; The laser emitting module is used to generate laser light and focus the laser light onto the surface of the target to be detected. The SIN chip detection module includes a SIN chip substrate and a micro-ring waveguide integrated on the SIN chip substrate; the micro-ring waveguide is connected to the input waveguide and the output waveguide respectively through coupling waveguides; The input waveguide is used to receive the probe laser; the micro-ring waveguide is used to resonantly modulate the probe laser; and the output waveguide is used to output the optical signal modulated by the micro-ring waveguide to the signal processing module. The signal processing module is used to process the optical signal obtained by the SIN chip detection module into ultrasonic signal characteristic parameters; The imaging module is used to reconstruct the image of the target to be detected based on the ultrasonic signal feature parameters obtained by the signal processing module.

2. The method according to claim 1, characterized in that, The microring waveguide is circular with an inner diameter of 5μm-10μm, an outer diameter of 6μm-11μm, and a waveguide width of 500nm-800nm.

3. The method according to claim 1, characterized in that, The thickness of the SIN chip substrate is 200nm-800nm.

4. The method according to claim 1, characterized in that, The detection laser has a different wavelength than the laser emitted by the laser emitting module.

5. The method according to claim 1, characterized in that, The laser emitting module includes a laser, a beam shaping assembly, and an optical path steering assembly; The laser is used to generate laser light; The beam shaping component is used to shape the laser generated by the laser into a parallel beam with a diameter of 100μm - 500μm; A light path steering assembly is used to focus the parallel light beam onto the surface of the target to be detected.

6. The method according to claim 1, characterized in that, The signal processing module includes a photodetector, a preamplifier, a data acquisition card, and an FPGA processing unit; The photodetector is used to receive the optical signal output from the SIN chip detection module and convert it into an electrical signal; The preamplifier is used to amplify and denoise the electrical signal; The data acquisition card is used to sample the signal processed by the preamplifier and convert it into a digital signal; The FPGA processing unit is used to process the digital signal to obtain ultrasonic signal characteristic parameters.

7. The method according to claim 1, characterized in that, The imaging module is specifically used to reconstruct the internal structure image of the target to be detected using an inversion algorithm, thereby obtaining a reconstructed image.

8. The method according to claim 1, characterized in that, The reconstructed image is any one of two-dimensional tomography, planar imaging, or 3D imaging.

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