Optical coherence elastography system and method based on portable probe

Abstract

The invention relates to an optical coherence elastography system and method based on a portable probe. The system comprises an OCT imaging unit and an excitation device. The OCT imaging unit comprises a light source, an optical fiber, a coupler, a circulator, a balance detector, a computer and a data acquisition card; the excitation device comprises a function generator, a signal amplifier and a probe; light emitted by the light source is divided into two paths by the first coupler according to the proportion of 90 / 10, wherein 10% of the path of light is irradiated on the reference mirror through the first circulator; 90% of the other path of light irradiates the surface of a measured object through a second circulator and a ball lens optical fiber in the probe, and signal light returned from the measured object and reference light returned from the reference mirror converge in a second coupler according to the proportion of 90 to 10 and interfere with each other; interference signals are acquired by the balance detector and transmitted to an acquisition card of the computer; waveforms output by the function generator are adjusted through the signal amplifier and transmitted to the probe, and the piezoelectric ceramic drives the probe to excite a measured object.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical detection equipment, and in particular relates to an optical coherence elastic imaging system and method based on a portable probe. Background Art

[0002] Pathological changes in biological tissues are often accompanied by changes in mechanical properties such as elasticity and stiffness. Elastic imaging techniques have been developed to visualize the distribution of strain and elastic modulus within soft tissues. Among various elastic imaging methods, optical coherence elastography (OCE) stands out for its superior resolution and sensitivity to deformation, surpassing the capabilities of ultrasound and magnetic resonance elastography. With the continuous advancement of experimental techniques and OCE algorithms, the development of portable devices is increasingly facilitating the non-destructive testing of tissue biomechanical properties.

[0003] Optical coherence tomography (OCT) uses the interference principle of near-infrared low-coherence light to generate high-resolution images, achieving radiation-free, damage-free and real-time imaging of living tissues. This technology has been widely used in the detection of ophthalmic diseases, and its application in other medical fields such as cardiovascular is also increasing. Optical coherence elastography (OCE) is a method that uses optical coherence tomography to capture the signal of tissue when it is deformed by force, thereby obtaining information on mechanical properties such as deformation or elastic modulus of the tissue. Compared with traditional strain and mechanical model calculation methods, elastic imaging technology can directly obtain the elastic modulus of the tissue by measuring the propagation speed of elastic waves, avoiding errors that may occur in the calculation process.

[0004] Handheld OCE probes have great benefits in clinical applications. Kennedy et al. [1] [2] [3] combined fiber-lensed optical coherence tomography (OCT) with a needle to measure tissue displacement in front of the tip during needle insertion. Although the probe is designed to be thin enough to penetrate deep into tissue, the lack of force sensing limits its measurement of mechanical parameters such as Young's modulus. To address this limitation, Qiu et al. [4] [5] developed a miniature OCE probe equipped with an integrated Fabry-Perot force sensor. This probe is able to apply compressive force to induce tissue deformation at its tip. By correlating the applied force with the resulting tissue deformation, it provides a method to quantify the biomechanical response of tissue to external stimuli. This probe can measure both force and displacement simultaneously. However, due to the complexity of biological tissue, force detection is complex and prone to errors. Wang et al. [6] made a side-view intravascular probe that excels at detecting deformation of vascular material in response to changes in vascular pressure. This probe has no mechanism for applying force and is specifically designed for scanning vascular samples. Qu et al. [7] introduced an acoustic radiation force OCE probe that integrates a miniature ultrasonic transducer with an OCT probe to obtain displacement data caused by acoustic radiation force. The displacement is extracted by phase analysis of the OCT interference signal. These displacement-based measurement techniques usually require additional equipment to measure the applied force, which may complicate the instrumentation. In addition, when considering the inherent strain-dependent material properties in biological tissues, these methods require complex inverse calculations to determine mechanical parameters such as elastic modulus.

[0005] Elastic wave-based OCE methods derive the elastic modulus of soft tissues from the propagation properties of elastic waves, thereby avoiding the need to measure the applied force. Liang et al. [8] proposed to excite the skin with harmonic surface waves and measure the Young's modulus from the wave velocity detected by OCT phase analysis. Li et al. [9] introduced a surface wave OCE method to evaluate the biomechanical properties of the skin, using a custom-made exciter to generate surface waves and calculating the phase velocity dispersion curve from OCT phase measurements. Larin

[10]

[11]

[12]

[13]

[14] developed contact and non-contact local methods to stimulate mechanical waves, using a speaker diaphragm with a thin hard wire to generate vibrations on the crystal lens, and also measured the velocity of elastic waves in the cornea of ​​living mice. Recently, the same group developed a focused air pulse technique to induce elastic waves, allowing the quantification of Young's modulus from the group velocity of elastic waves without physical contact. Using this air pulse OCE method, the Young's modulus of diseased and normal skin was measured in vivo. Li et al.

[15] used laser-induced surface acoustic waves (SAW) to measure the elastic properties of the skin by detecting the wave velocity through OCT phase analysis. Singh et al.

[16] proposed a method for measuring the elasticity of soft biological tissues using Rayleigh wave tracking holographic imaging. Although previous studies have confirmed the effectiveness of surface wave imaging in characterizing the elastic properties of skin, the systems used in these studies are often bulky and not conducive to convenient application.

[0006] To make OCE systems more convenient for clinical use, Parmar et al.

[17] designed an OCE probe based on a flexible common-path fiber and a piezoelectric sensor. The shear wave formula was applied, where is the material density and is the surface wave velocity in the sample to calculate the Young's modulus of the skin. This single-point detection method depends on the precise synchronization between the piezoelectric transducer and the OCT acquisition. To address the synchronization problem, Latus et al.

[18] proposed a dual-fiber OCE probe to estimate tissue elasticity by measuring the shear wave propagation time between two points. The probe contains two optical fibers, allowing the time difference to be measured in the form of waves moving between two detection points. This approach simplifies the process by focusing only on local wave propagation. However, combining shear wave excitation ultrasound probes with fiber alignment results in larger and more complex wave generation and detection components. In these studies, the soft tissue material was assumed to be homogeneous, limiting the accuracy of the derived mechanical parameters. Elastic waves were simplified to shear waves or surface waves, but this has not been verified.

[0007] The properties of the excited elastic waves are closely related to the mechanical parameters required for OCE. When a half-space medium is vertically excited, three types of elastic waves are usually generated: shear waves, longitudinal waves, and surface waves. Among these, surface waves account for about 70% of the total energy and decay much slower than other wave types. Previous studies have shown that using piezoelectric ceramics to drive probes to excite surface waves in double-layer biomaterials has great potential. The Young's modulus of each layer was measured based on the propagation of Rayleigh waves. However, the measurement of the mechanical properties of multilayers still requires in-depth research on the characteristics of the waves. Summary of the invention

[0008] In view of the deficiencies in the prior art, the present invention provides an optical coherence elastic imaging system and method based on a portable probe.

[0009] One of the above objects of the present invention is achieved by the following technical solution:

[0010] An optical coherence elastic imaging system based on a portable probe, comprising an OCT imaging unit and an excitation device;

[0011] The OCT imaging unit includes a light source, an optical fiber, a coupler, a circulator, a balanced detector, a computer and a data acquisition card; the excitation device includes a function generator, a signal amplifier and a probe;

[0012] The light source is used to generate high-speed scanning laser; the coupler includes a first coupler and a second coupler, the circulator includes a first circulator and a second circulator, and the balanced detector is used to convert the optical signal into an electrical signal;

[0013] The light emitted by the light source is divided into two paths by the first coupler at a ratio of 90 / 10, of which 10% of the light is irradiated on the reference mirror through the first circulator; the other 90% of the light is irradiated on the surface of the measured object through the second circulator and the ball lens optical fiber in the probe. The signal light returned from the measured object and the reference light returned from the reference mirror merge and interfere at the second coupler at a ratio of 90:10; the interference signal is collected by the balanced detector and transmitted to the acquisition card of the computer;

[0014] The function generator is used to generate elastic waves according to experimental requirements; the signal amplifier is used to adjust the voltage and control the signal strength; the probe is an excitation execution terminal component, which includes a stainless steel shell, a ball lens optical fiber wrapped in the stainless steel shell, and an axially movable probe arranged in the stainless steel shell, the head end of the probe is pointed, and the tail end of the probe is attached to the piezoelectric ceramic, and the piezoelectric ceramic is electrically connected to the signal amplifier; there is an indirection between the tip of the probe and the ball lens optical fiber;

[0015] The waveform output by the function generator is adjusted by the signal amplifier and transmitted to the probe, and the piezoelectric ceramic drives the probe to excite the measured object.

[0016] Moreover, the light source adopts a high-speed frequency-sweeping laser with a scanning frequency of 100 KHz and a central wavelength of 1310 nm.

[0017] Also, the tip diameter of the probe is 0.5 mm, and the tip of the probe extends 0.2 mm from the bottom of the housing.

[0018] Moreover, the working distance of the ball lens fiber is 5 mm and the beam waist diameter is 20 μm.

[0019] Furthermore, the piezoelectric ceramic has a maximum spacing of 8.5 μm at a voltage of 150 V.

[0020] Furthermore, the distance between the probe tip and the ball lens fiber is 1.8 mm.

[0021] The second objective of the present invention is achieved by the following technical solutions:

[0022] A method for measuring elastic modulus using the above-mentioned optical coherence elastic imaging system based on a portable probe can be used to measure the equivalent elasticity of multi-layer skin tissue in vivo, comprising the following steps:

[0023] Step 1: Given a known interval between an excitation point and a detection point, measure the time required for an elastic wave to pass through the interval, wherein the excitation point is the position where the probe acts, and the detection point is the position detected by the ball lens optical fiber;

[0024] Step 2, calculating the average velocity of the elastic wave according to the propagation time of the elastic wave between the two points measured in step 1;

[0025] Step 3: Calculate the Young's modulus of the object to be measured according to the average propagation velocity of the elastic wave calculated in step 2.

[0026] Furthermore, step 1 includes:

[0027] 1.1 The displacement caused by the propagation of elastic waves is confirmed by phase analysis of the OCT signal, as described in the following formula:

[0028]

[0029] Wherein, d(z, t) represents the displacement at depth z at time t; ΔΦ(z, t) represents the phase difference between the phase at time t and the phase before excitation; n is the refractive index of the object being measured, and λ0 is the central wavelength of the laser light source; assuming n and λ0 are constants, the displacement d(z, t) is proportional to the phase difference ΔΦ(z, t);

[0030] 1.2. The phase difference is calculated by cross-correlating the phase of each subsequent line scan with the phase of the initial scan, as shown in the following formula:

[0031]

[0032] Where I(z,t) is the composite OCT A scan signal at time t, and I(z,t0) * is the conjugate of the pre-excitation composite OCT A-scan signal, which occupies the first line in the M-mode image.

[0033] 1.3. Apply the minimum cost flow phase unwrapping method to unpack the phase difference in 1.2, and substitute the unpacked phase difference into the formula in 1.1 to obtain the displacement profile. The displacement change curve over time shows the vibration of the detection point caused by the elastic wave. The time when the displacement curve drops sharply for the first time is determined as the time when the elastic wave reaches the detection point.

[0034] Furthermore, in step 2, the average velocity of the elastic wave is calculated by the following formula:

[0035]

[0036] Where Δx is the preset distance from the detection point to the excitation point, and Δt is the time it takes for the elastic wave to propagate through the distance.

[0037] Furthermore, in step 3:

[0038] The propagation velocity of shear waves is related to the material properties of the medium, as shown in the following formula:

[0039]

[0040] Where E is Young's modulus, v is Poisson's ratio, p is density, and surface wave velocity C is R is 0.946 times of Cs; the velocity obtained by formula (3) is set to the surface wave velocity C of the skin-like layered tissue R Equivalently, the Young's modulus of the equivalent elasticity of the multilayer tissue is solved by substituting the surface wave velocity into equation (4).

[0041] The advantages and positive effects of the present invention are:

[0042] The optical coherence elastic imaging system and method based on a portable probe proposed in the present invention can be used to measure the elasticity of multiple layers of superficial soft tissue in vivo. The present invention integrates piezoelectric ceramics and spherical lens optical fiber into its design, replaces the excitation generator and scanning lens, simulates the waves in the multi-layer structure through mechanical stimulation, establishes the relationship between the wave velocity and the equivalent Young's modulus of the sample, thereby realizing the measurement of the equivalent elastic modulus of multi-layer tissues, and providing a convenient and effective measurement method for non-destructive testing of the mechanical properties of biological tissues. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1It is a schematic diagram of the optical device of the handheld probe OCE system of the present invention;

[0044] Figure 2 It is a picture of the handheld probe of the present invention;

[0045] Figure 3 This is an OCE measurement picture of a single-layer phantom according to the first embodiment of the present invention;

[0046] Figure 4 is a phase difference image measured by a single-layer phantom according to the first embodiment of the present invention;

[0047] Figure 5 is the displacement distribution of the surface area of ​​the single-layer phantom according to the first embodiment of the present invention;

[0048] Figure 6 is the average displacement of the surface of the single-layer phantom along the depth according to the first embodiment of the present invention;

[0049] Figure 7 is a phase difference image measured by a three-layer phantom according to the second embodiment of the present invention;

[0050] Figure 8 is the displacement distribution of the surface area of ​​the three-layer phantom according to the second embodiment of the present invention;

[0051] Fig. 9 is the average displacement of the three-layer phantom surface along the depth of the second embodiment of the present invention. DETAILED DESCRIPTION

[0052] The structure of the present invention is further described below with reference to the accompanying drawings and by way of examples. It should be noted that the present examples are descriptive rather than restrictive.

[0053] A portable probe-based optical coherence elastic imaging system, see Figure 1-Figure 2 The invention point is: it includes an OCT imaging unit and an excitation device; the excitation device is used to generate elastic waves and excite the measured object, and the OCT imaging unit is used to collect surface signals of the measured object and output them as pictures. The OCT imaging unit includes a light source, an optical fiber, a coupler, a circulator, a balanced detector, a computer and a data acquisition card; the excitation device includes a function generator, a signal amplifier and a probe.

[0054] Light source: High-speed frequency-sweeping laser with a scanning frequency of 100KHz and a central wavelength of 1310nm.

[0055] Coupler: includes a first coupler and a second coupler, the first coupler is used to split the optical signal of the laser emitted by the light source, and the second coupler is used to realize the combination of the reference return optical signal and the detection return optical signal.

[0056] Circulator: Ensures that signals in different directions do not interfere with each other, thereby improving transmission efficiency. It includes a first circulator and a second circulator, wherein the first circulator is used to realize the transmission of reference light information, and the second circulator is used to realize the transmission of detection light signals, wherein the light signal irradiated to the reference mirror and the returned light signal through the first circulator are transmitted by the same optical fiber, and the light signal interference is avoided through the circulator. The light information irradiated to the object and the returned light signal through the second circulator are transmitted by one optical fiber, and the light signal interference is avoided through the circulator

[0057] Balanced detector: used to convert optical signals into electrical signals.

[0058] The light emitted by the light source is divided into two paths by the first coupler at a ratio of 90 / 10: one path of 10% of the light is irradiated on the reference mirror through the first circulator; the other path of 90% is irradiated on the surface of the object through the second circulator and the ball lens optical fiber in the probe. The signal light returned from the object and the reference light returned from the reference mirror merge and interfere at the second coupler at a ratio of 90:10. The interference signal is collected by the balanced detector and transmitted to the acquisition card of the computer.

[0059] Function generator: used to generate elastic waves according to experimental requirements.

[0060] Signal amplifier: used to adjust voltage and control signal strength.

[0061] Probe: The end member that excites and executes the excitation.

[0062] The probe is equipped with a ball lens fiber and piezoelectric ceramics (DCS3-070709, DCpiezo, China). A probe with a tip diameter of 0.5 mm is attached to the end of the piezoelectric ceramic. The stainless steel housing wraps the ball lens fiber and supports the probe on the surface of the measured object. The piezoelectric ceramic is able to produce a maximum displacement of 8.5 μm at a voltage of 150 V, and the displacement is almost proportional to the applied voltage. For all experiments, a voltage of 100 V was applied, resulting in an excitation amplitude of 5.6 μm. The working distance of the ball lens is 5 mm and the beam waist diameter is 20 μm. The probe extends 0.2 mm from the bottom of the shell to ensure contact with the measured object. The distance between the probe tip and the ball lens fiber is adjustable and set to 1.8 mm to ensure that a stable elastic wave signal is detected.

[0063] The waveform output by the function generator is adjusted by the signal amplifier and then transmitted to the probe, where the piezoelectric ceramic drives the probe for excitation.

[0064] The above-mentioned optical coherence elastic imaging system based on a portable probe can be used to measure the equivalent elasticity of multi-layer skin tissue in vivo. The steps for measuring the elastic modulus are as follows:

[0065] Step 1: Given a known interval between an excitation point and a detection point, measure the time required for an elastic wave to pass through the interval, where the excitation point is the position where the probe acts and the detection point is the position detected by the spherical lens optical fiber.

[0066] Step 2: Calculate the average velocity of the elastic wave based on the propagation time of the elastic wave between the two points measured in step 1.

[0067] Step 3: Calculate the Young's modulus of the object to be measured according to the average propagation velocity of the elastic wave calculated in step 2.

[0068] In step 1:

[0069] Phase analysis of the OCT signal is used to detect the displacement caused by the propagation of elastic waves as described by the following equation:

[0070]

[0071] Where d(z,t) represents the displacement at depth z at time t; ΔΦ(z,t) represents the phase difference between the phase at time t and the phase before excitation; n is the refractive index of the object being measured, and λ0 is the central wavelength of the laser light source. Assuming n and λ0 are constants, the displacement d(z,t) is proportional to the phase difference ΔΦ(z,t).

[0072] For step 1, given a known interval between the excitation point and the detection point, the time required for the elastic wave to cross the gap is measured. In order to precisely locate the moment when the elastic wave arrives at the detection point, a 1ms delay is programmed into the excitation sequence of the probe after the OCT B scan is started. During the measurement, the probe is applied to the object surface. A sinusoidal pulse is input into the piezoelectric ceramic, and M-mode OCT data is captured for 20ms. To mitigate the effects of noise, each experiment is performed 20 times and the 20 data are added and averaged. The phase change is calculated by cross-correlating the phase of each subsequent line scan with the initial scan:

[0073]

[0074] Where I(z,t) is the composite OCT A scan signal at time t, and I(z,t0) * is the conjugate of the composite OCT A-scan signal before excitation, which occupies the first line in the M-mode image in this experiment. Because ΔΦ(z,t) is usually wrapped in [-π, π], the minimum cost flow phase unwrapping method is applied. Substituting the unwrapped ΔΦ(z,t) into equation (1) yields the displacement profile. The displacement versus time curve illustrates the vibration of the detection point caused by the elastic wave. The time of the first sharp drop in the displacement curve is determined as the time when the elastic wave arrives at the detection point.

[0075] In step 2:

[0076] After obtaining the propagation time of the elastic wave, the average velocity of the elastic wave can be simply calculated by the following formula:

[0077]

[0078] Where Δx is the preset distance from the detection point to the excitation point, which is 1.8 mm according to the probe design. Δt is the time it takes for the elastic wave to propagate through the distance.

[0079] In step 3:

[0080] The propagation speed of shear waves is related to the material properties of the medium:

[0081]

[0082] E is Young's modulus, v is Poisson's ratio, and p is density. Surface wave velocity C R It is about 0.946 of Cs. The velocity obtained by equation (3) is set to the surface wave velocity C of the skin-like layered tissue. R Therefore, the surface wave velocity can be substituted into equation (4) to solve the Young's modulus of the equivalent elasticity of the multilayer tissue.

[0083] Example:

[0084] The optical elastic imaging method proposed in the present invention includes two basic steps: the setting of an excitation device and the setting of an optical coherence tomography device (ie, an OCT imaging unit).

[0085] The excitation waveform is set by the function generator and power amplifier. The function generator and data acquisition are triggered and controlled by software. The probe vibration and data acquisition can be simultaneous in time or a certain delay can be set according to the test needs. Place the portable probe on the surface of the test piece.

[0086] Setup of the optical coherence tomography device: Upon triggering, the piezoelectric ceramic hits the surface of the object through the probe to generate elastic waves. M-mode OCT imaging is performed to detect the propagation of these waves, capturing the dynamic interaction through the ball lens fiber. For each trigger, 2000 A scans are recorded, corresponding to a 20ms data acquisition window. The wave velocity of the elastic wave is determined by the distance between the excitation point and the point to be measured and the time between the excitation and the point to be measured.

[0087] Single-layer and three-layer models were made for the present invention. Two parts of food-grade silica gel (Yuchen Silica Gel, China) component A and component B were mixed in a 1:1 ratio, and 0.02% TiO2 was added to the mixture as a scattering agent. The components were mixed thoroughly and vacuum treated for one hour to remove bubbles from the mixed solution. The diameter of this body membrane was 40 mm, the height was 38 mm, and the measured density was 1.17×103 kg / m 3 The three-layer silicone phantom is made by curing two layers of silicone on a single layer. The top, middle and bottom layers are made of silicone materials with Shore hardness of 35, 25 and 15 respectively, and the cumulative thickness of the phantom is 6mm.

[0088] Phase difference map acquired during the application of a sine wave pulse to the phantom. The original M-mode OCT image consists of 1024 pixels in the vertical direction and 2000 pixels in the horizontal direction, which translates to a depth range of 9.68 mm and an imaging time span of 20 ms. Given the limited penetration depth of OCT, deeper regions mainly exhibit noise, so only the first 300 pixels were retained for analysis. For the study of surface wave properties, 10 lines of data adjacent to the sample surface were carefully examined. The phase difference in the selected near-surface region was expanded and subsequently input into equation (1) to calculate the displacement.

[0089] The scanned images were processed to obtain a curve of the displacement of the surface layer of the phantom over time. At about 1ms in the single-layer phantom, the waveform showed a slight rise before a significant drop, indicating the propagation of the surface wave. The sharpest drop observed at 1.18ms was determined to be the moment when the surface wave arrived at the detection point. Considering the 1ms interval between the start of OCT imaging and the actuator excitation, the propagation time Δt of the elastic wave from the excitation to the detection point was calculated to be 0.18ms. Assuming that the distance Δx from the excitation to the detection point is 0.18mm, the wave velocity is determined to be 10.0m / s, which corresponds to 0.946 times the shear wave velocity. The elastic modulus can be calculated to be 389.60kPa. This value is very consistent with the 394.56kpa obtained by the tensile test, resulting in only a 1.25% difference. In the curve of the three-layer phantom, the arrival time of the wave is 0.15ms. From this, the speed of the wave is determined to be 12.0m / s. The equivalent Young's modulus of the phantom was calculated to be 561.03 kPa, which differed by about 1.17% from the 567.70 kPa measured by the tensile test.

[0090] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. An optical coherence elastic imaging system based on a portable probe, characterized in that: It includes an OCT imaging unit and an excitation device; The OCT imaging unit includes a light source, an optical fiber, a coupler, a circulator, a balanced detector, a computer and a data acquisition card; the excitation device includes a function generator, a signal amplifier and a probe; The light source is used to generate high-speed scanning laser; the coupler includes a first coupler and a second coupler, the circulator includes a first circulator and a second circulator, and the balanced detector is used to convert the optical signal into an electrical signal; The light emitted by the light source is divided into two paths by the first coupler at a ratio of 90 / 10, of which 10% of the light is irradiated on the reference mirror through the first circulator; the other 90% of the light is irradiated on the surface of the measured object through the second circulator and the ball lens optical fiber in the probe. The signal light returned from the measured object and the reference light returned from the reference mirror merge and interfere at the second coupler at a ratio of 90:10; the interference signal is collected by the balanced detector and transmitted to the acquisition card of the computer; The function generator is used to generate elastic waves; the signal amplifier is used to adjust the voltage and control the signal strength; the probe is an excitation execution terminal component, which includes a stainless steel shell, a ball lens optical fiber wrapped in the stainless steel shell, and an axially movable probe arranged in the stainless steel shell, the head end of the probe is pointed, and the tail end of the probe is attached to the piezoelectric ceramic, and the piezoelectric ceramic is electrically connected to the signal amplifier; there is an indirection between the tip of the probe and the ball lens optical fiber; The waveform output by the function generator is adjusted by the signal amplifier and transmitted to the probe, and the piezoelectric ceramic drives the probe to stimulate the measured object.

2. The optical coherence elastic imaging system based on a portable probe according to claim 1, characterized in that: The light source adopts a high-speed frequency-sweeping laser with a scanning frequency of 100 KHz and a central wavelength of 1310 nm.

3. The optical coherence elastic imaging system based on a portable probe according to claim 1, characterized in that: The tip diameter of the probe is 0.5 mm, and the probe tip extends 0.2 mm from the bottom of the housing.

4. The optical coherence elastic imaging system based on a portable probe according to claim 1, characterized in that: The working distance of the ball lens fiber is 5mm and the beam waist diameter is 20μm.

5. The optical coherence elastic imaging system based on a portable probe according to claim 1, characterized in that: The piezoelectric ceramic has a maximum spacing of 8.5 μm at a voltage of 150 V.

6. The optical coherence elastic imaging system based on a portable probe according to claim 1, characterized in that: The distance between the probe tip and the ball lens optical fiber is 1.8 mm.

7. A method for measuring elastic modulus using the portable probe-based optical coherence elastic imaging system according to any one of claims 1 to 6, characterized in that: The equivalent elasticity of multiple layers of skin tissue can be measured in vivo, including the following steps: Step 1: Given a known interval between an excitation point and a detection point, measure the time required for an elastic wave to pass through the interval, wherein the excitation point is the position where the probe acts, and the detection point is the position detected by the ball lens optical fiber; Step 2, calculating the average velocity of the elastic wave according to the propagation time of the elastic wave between the two points measured in step 1; Step 3: Calculate the Young's modulus of the object to be measured according to the average propagation velocity of the elastic wave calculated in step 2.

8. The elastic modulus measurement method using an optical coherence elastic imaging system based on a portable probe according to claim 7, characterized in that: Step 1 includes: 1.1 The displacement caused by the propagation of elastic waves is confirmed by phase analysis of the OCT signal, as described in the following formula: Wherein, d(z, t) represents the displacement at depth z at time t; ΔΦ(z, t) represents the phase difference between the phase at time t and the phase before excitation; n is the refractive index of the object being measured, and λ0 is the central wavelength of the laser light source; assuming n and λ0 are constants, the displacement d(z, t) is proportional to the phase difference ΔΦ(z, t); 1.

2. The phase difference is calculated by cross-correlating the phase of each subsequent line scan with the phase of the initial scan, as shown in the following formula: Where I(z,t) is the composite OCT A scan signal at time t, and I(z,t0) * is the conjugate of the pre-excitation composite OCT A-scan signal, which occupies the first line in the M-mode image. 1.

3. Apply the minimum cost flow phase unwrapping method to unpack the phase difference in 1.2, and substitute the unpacked phase difference into the formula in 1.1 to obtain the displacement profile. The displacement change curve over time shows the vibration of the detection point caused by the elastic wave. The time when the displacement curve drops sharply for the first time is determined as the time when the elastic wave reaches the detection point.

9. The elastic modulus measurement method using an optical coherence elastic imaging system based on a portable probe according to claim 7, characterized in that: In step 2, the average velocity of the elastic wave is calculated by the following formula: Where Δx is the preset distance from the detection point to the excitation point, and Δt is the time it takes for the elastic wave to propagate through the distance.

10. The elastic modulus measurement method using an optical coherence elastic imaging system based on a portable probe according to claim 9, characterized in that: In step 3: The propagation velocity of shear waves is related to the material properties of the medium, as shown in the following formula: Where E is Young's modulus, v is Poisson's ratio, p is density, and surface wave velocity C is R is 0.946 times of Cs; the velocity obtained by formula (3) is set to the surface wave velocity C of the skin-like layered tissue R Equivalently, the Young's modulus of the equivalent elasticity of the multilayer tissue is solved by substituting the surface wave velocity into equation (4).

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