A multi-core fiber based spatial shape sensing and three-dimensional imaging apparatus and method

Abstract

This invention relates to a spatial shape sensing and three-dimensional imaging device and method based on multi-core optical fibers. Two functions can be simultaneously achieved using a bundle of combined multi-core optical fibers: spatial shape sensing and three-dimensional imaging. The outer spiral grating fiber bundle of this invention can detect the curvature and torsion of the fiber through fiber deformation, and then reconstruct the spatial shape according to a spatial curve reconstruction algorithm. Traditional endoscopic imaging typically only performs two-dimensional imaging, while this invention, using computational imaging technology, directly recovers the phase information of the target tissue through iterative calculation based on the received diffraction image, and achieves three-dimensional imaging of the target tissue through wavefront inversion technology. Simultaneously, spatial information from different times is fused with imaging information to achieve visual representation.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic sensing technology, specifically relating to a spatial shape sensing and three-dimensional imaging device and method based on multi-core optical fiber. Background Technology

[0002] With advancements in medical testing technology, healthcare professionals can utilize various advanced instruments to examine patients, accurately diagnose illnesses, and proactively halt disease progression to alleviate symptoms. However, because the esophagus and intestines contain gas and food residue, external imaging methods cannot be used. This necessitates the use of medical instruments that leverage the body's natural pathways for internal imaging. Endoscopes are a commonly used medical instrument that allows healthcare professionals to directly observe the patient's internal tissues and lesions through the body's natural pathways.

[0003] During insertion, the endoscope may become entangled or twisted due to the natural walls of the body's passageways. This not only leads to misalignment of the examination site but also increases patient discomfort. To detect the shape of the endoscope within the body and acquire its status at different times and positions during insertion, thus effectively determining the location of lesions, a common method is to integrate optical fibers into the endoscope's cannula. The fiber optics then perform shape sensing to obtain the endoscope's morphology. This undoubtedly increases the diameter of the endoscope cannula, significantly impacting the patient's experience.

[0004] Meanwhile, endoscopes typically only provide two-dimensional imaging, making it impossible to determine the depth or thickness of the target tissue. Three-dimensional information about the target tissue, however, can greatly assist healthcare professionals in assessing a patient's condition and aiding in the diagnosis. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a spatial shape sensing and three-dimensional imaging device and method based on multi-core optical fibers. Spatial shape sensing can detect the position and state of the optical fiber at different times during the feeding process in real time, while three-dimensional imaging can perform quantitative phase imaging of target tissue. This invention achieves both functions simultaneously through a bundle of combined optical fibers. The helical grating fiber in the combined fiber reconstructs the three-dimensional shape of the fiber through strain measurement, achieving the purpose of spatial shape sensing; the straight fiber bundle in the combined fiber acquires diffraction intensity maps to achieve three-dimensional imaging of in vivo tissue. This invention requires only a single, specially designed fiber bundle to achieve both spatial shape sensing and three-dimensional imaging of target tissue; the diameter of the designed fiber bundle is on the order of micrometers.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A spatial shape sensing and three-dimensional imaging device based on multi-core optical fiber includes: a light source module, an optical fiber fan-in / fan-out module, a combined multi-core optical fiber probe module, a shape sensing module, an imaging module, and a data processing module.

[0008] The light source module transmits optical signals through optical fibers and provides illumination light for imaging.

[0009] The fiber optic fan-in / fan-out module is used to integrate optical fibers with different functions into a single bundle, and connects the shape sensing module and the imaging module.

[0010] The multi-core fiber optic module consists of two parts. The first part comprises multiple outer spiral fibers and a single central independent fiber. Gratings are etched inside the fibers in this part. The outer spiral fibers are used for strain and spatial shape sensing, while the central independent fiber is used for temperature and strain compensation. The second part consists of two straight fiber bundles wrapped around the central independent fiber, without gratings. The first layer is a transmitting fiber used to emit illumination light, and the second layer is a receiving fiber used to receive the object light reflected back from the target tissue.

[0011] The shape sensing module includes a grating demodulator, which is connected to the outer spiral fiber of the multi-core fiber module through the fiber fan-in and fan-out modules to convert the received center wavelength drift into strain.

[0012] The imaging module includes a CCD camera, which is connected to the receiving fiber of the straight fiber bundle of the fiber fan-in and fan-out module and the multi-core fiber module to receive the diffraction image modulated by the multi-core fiber.

[0013] The data processing module, including a computer, converts the strain detected by the shape sensing module into a three-dimensional shape to achieve spatial shape perception; it performs quantitative phase recovery on the diffraction images received by the imaging module to achieve target tissue imaging. Simultaneously, it fuses the fiber optic positions at different times with the three-dimensional imaging data to achieve real-time visualization.

[0014] A spatial shape sensing and 3D imaging method based on multi-core optical fiber, the specific implementation steps of which are as follows:

[0015] Step 1: The light source module serves as the stable signal source and illumination light for the optical fiber, while the fiber fan-in and fan-out modules integrate the designed multifunctional combined optical fibers; the optical signal passes through the entire combined multi-core fiber probe module, simultaneously illuminating the target tissue;

[0016] Step 2: When the optical fiber is bent or twisted, the optical fiber will deform, and the grating pitch of the outer spiral grating optical fiber will change accordingly, causing the center wavelength of the signal reflected by the grating to drift. The amount of wavelength change can be detected by the grating demodulator of the shape sensing module.

[0017] Step 3: Calculate the fiber strain using the center wavelength shift. The center wavelength shift Δλ and the strain ε have the following relationship:

[0018]

[0019] Where P e λ is the photoelastic coefficient related to the optical fiber material, and λ is the center wavelength of the grating fiber. Since the independent grating fiber in the center of the combined multi-core optical fiber module does not deform during bending and is also less affected by temperature when wrapped in the fiber bundle, it serves as a compensation for strain and temperature, thereby eliminating environmental influences and system errors.

[0020] Step 4: Calculate fiber curvature using fiber strain; there is also a quantitative relationship between fiber strain and its curvature κ(s), expressed as follows:

[0021]

[0022]

[0023] In the above formula, ε i Let r be the axial strain of the i-th fiber. i θ is the distance from the i-th fiber to the center of the fiber. b θ is the angle from the bending direction of the optical fiber to the y-axis. i θ is the angle from the i-th fiber to the y-axis. avg ρ is the angle between uniformly distributed optical fibers, and ρ is the radius of curvature. The discrete fiber curvature can be obtained by formulas (2) and (3). By fitting the difference in the fiber bending direction, the continuous curvature function κ(s) can be obtained.

[0024] Step 5: Calculate the fiber torsion using fiber strain; there is also a quantitative relationship between fiber strain and its torsion τ(s), expressed as follows:

[0025]

[0026] In the above formula, L p L is the fiber pitch, and L is the original length corresponding to the helical fiber pitch. ε θ is the length after twisting, θ is the twist angle, and r is the distance from the spiral fiber to the center of the fiber.

[0027] The discrete fiber twist angle can be obtained by formula (4). By fitting the difference in the fiber bending direction, the continuous torsion function θ(s) with respect to the arc length s can be obtained.

[0028] τ(s)=θ'(s) (5)

[0029] By differentiating θ(s) from formula (5), the torsion function τ(s) of the optical fiber can be obtained.

[0030] Step 6: Solve the Frenet-Serret equations using curvature and torsion. Substitute the curvature κ(s) and torsion τ(s) into the Frenet-Serret equations:

[0031]

[0032] Where T(s) represents the tangent vector, N(s) represents the normal vector, and B(s) represents the binormal vector. The tangent vector function T(s) is then obtained numerically by calculating the curvature and torsion at each point.

[0033] Step 7: Solve for the fiber shape using the tangent vector function. The curve's function with respect to arc length s can be obtained by calculating the tangent vector function T(s), as shown below:

[0034] r(s)=∫T(s)ds+r0 (7)

[0035] The shape distribution of the optical fiber can be obtained through formula (7), thereby realizing the function of spatial shape perception. Here, r0 represents the initial position of the optical fiber starting point in this coordinate system.

[0036] Step 8: During the fiber feeding process, the transmitting fiber in the straight fiber bundle of the combined multi-core fiber probe module is always in the state of emitting optical signals. When it reaches the vicinity of the target tissue, the receiving fiber in the straight fiber bundle of the combined multi-core fiber probe module will receive the optical signal reflected back by the target tissue. After being modulated by different fibers, the diffraction intensity map is finally acquired by the CCD of the imaging module.

[0037] Step 9: Perform iterative calculations using computational imaging methods to achieve quantitative phase recovery. The diffraction intensity captured by the CCD acquisition surface is light intensity I, and the initial guess of the phase of the acquisition surface is... The iterative process is as follows: (n represents the nth iteration, Indicates forward transmission. (Indicates reverse transmission)

[0038] 1) Perform an initial estimation of the sampling surface, assuming its distribution is as follows: i is the imaginary unit;

[0039] 2) Backpropagation to the target tissue plane yields the target tissue plane distribution. And perform planar constraints;

[0040] 3) Propagate forward from the target tissue plane to the collection surface to obtain the collection surface distribution.

[0041] 4) Perform acquisition plane constraints to maintain phase. The calculated amplitude remains unchanged, and is replaced with the square root of the recorded intensity.

[0042] 5) Backpropagation from the recording plane to the sample plane

[0043] 6) Determine if convergence has occurred. If the error is less than the set value, output the result; if it is greater, perform sample plane constraints, update using the HIO algorithm, and proceed to the next iteration.

[0044]

[0045] In the formula, r is the object plane coordinate system, and Q represents e. n 'The set of points in the region that does not satisfy the spatial constraints, where ε∈[0.5,1] is a constant.

[0046] Its transmission process generally uses angular spectrum transmission, as shown in formula (9):

[0047] A(ξ,η)=A0(ξ,η)H(ξ,η) (9)

[0048] In the formula, ξ and η are spatial frequency components, A(ξ,η) and A0(ξ,η) are the input and output spectra of the system, and H(ξ,η) is the angular spectral transfer factor.

[0049]

[0050] In the formula, z is the transmission distance, λ is the wavelength, k is the wave number, and j is the imaginary unit.

[0051] Step 10: Calculate the phase information of the target tissue plane and its spatial position before and after it; After step 9, the phase information of the acquisition plane is calculated, and then it is diffracted back to the target tissue plane and its spatial position before and after it through angular spectrum transmission to recover the phase information of multiple planes, thereby achieving the purpose of three-dimensional imaging; At the same time, the position information obtained by spatial shape perception is fused with the three-dimensional imaging information to achieve the purpose of visualization.

[0052] This invention aims to achieve two objectives. First, it enables real-time spatial shape perception of optical fibers within the human body. After the optical fiber enters the body through the body's channels, spatial shape perception helps medical professionals understand the depth of penetration and the approximate location reached. However, due to the fiber's feeding motion, it may twist and coil within the body channels, leading to misjudgments of the detection site. This invention's outer spiral grating fiber bundle can detect the fiber's curvature and torsion at a specific location through fiber deformation detection, and then reconstruct the three-dimensional spatial shape using a spatial curve reconstruction algorithm. Spatial shape perception helps medical professionals adjust the feed rate, obtain the fiber's position and state at different times, accurately determine the detection site, and avoid harm to the body caused by fiber entanglement. Second, it enables three-dimensional imaging of target tissue. Imaging target tissue is an effective means of detecting lesions, but traditional endoscopic imaging typically only provides two-dimensional imaging. This invention, using computational imaging technology, directly recovers the target tissue's phase information through iterative calculation based on the received diffraction image, and achieves three-dimensional imaging of the target tissue through wavefront inversion technology. Simultaneously, the location information obtained from spatial shape perception can be fused with three-dimensional imaging information to achieve the purpose of visualization.

[0053] Compared with the prior art, the present invention has the following prominent substantive features and significant technological advancements:

[0054] 1. This invention designs a combined optical fiber, avoiding the traditional medical examination method of placing the optical fiber inside the endoscope channel, detecting shape through the optical fiber, and then imaging through the endoscope. Instead, it combines the functions of spatial shape perception and three-dimensional imaging into one, which can be accomplished through a single bundle of combined optical fibers. Moreover, the physical diameter of the combined multi-core optical fiber module of this invention is less than 1 / 10 of that of a traditional endoscope, greatly reducing patient discomfort during the examination.

[0055] 2. The composite optical fiber designed in this invention features a spiral grating fiber as its outer layer for spatial shape sensing. Traditional optical fiber shape sensing uses straight fibers, detecting strain and converting it to curvature. The deflection is then obtained by differentiating the rotation angle, resulting in inaccurate deflection calculations and neglecting the deformation caused by fiber torsion. This invention uses a spiral fiber, which is more sensitive to torsion sensing and can generate torsion compensation, thus accurately detecting deflection through strain. A spatial curve reconstruction algorithm is then used to reconstruct the spatial shape in three dimensions.

[0056] 3. The combined optical fiber designed in this invention consists of a bundle of straight optical fibers without grating markings, part of which is a transmitting fiber and part is a receiving fiber. The transmitting fiber emits illumination light to illuminate the target tissue, while the receiving fiber receives the returned diffracted light and transmits it to the CCD of the imaging module for imaging. The diffraction image is then processed using computational imaging techniques. Through iterative calculations, quantitative phase information at corresponding locations can be obtained. Furthermore, based on its wavefront inversion capability, the phase information at different locations can be quantitatively imaged, thereby enabling three-dimensional imaging of the target tissue. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the overall structure provided by the present invention.

[0058] Figure 2 This is a schematic diagram of the overall device provided by the present invention.

[0059] Figure 3 This is a flowchart of the spatial shape perception and computational imaging process provided by the present invention.

[0060] Figure 4 This is a schematic diagram of the combined multi-core optical fiber designed in this invention.

[0061] Figure 5 This is a cross-sectional view of the outer spiral optical fiber designed in this invention.

[0062] Figure 6 This is a side view of the unit pitch of the combined multi-core optical fiber designed in this invention. Detailed Implementation

[0063] The embodiments of the present invention are described in detail below with reference to the accompanying drawings:

[0064] This invention provides a spatial shape sensing and three-dimensional imaging device and method based on multi-core optical fiber.

[0065] like Figure 1 As shown, this device mainly includes a light source module, an optical fiber fan-in / fan-out module, a combined multi-core optical fiber probe module, a shape sensing module, an imaging module, and a data processing module.

[0066] Combination Figure 2 and Figure 3A detailed process description is provided: after the optical signal enters the optical fiber, it passes through the fiber fan-in / fan-out module to reach the designed combined optical fiber probe module. If the optical fiber bends or twists at this point, the grating pitch of the outer spiral grating fiber of the combined multi-core optical fiber probe module will change, resulting in a change in the wavelength of the returned optical signal after passing through the grating. The grating demodulator of the shape sensing module receives the returned optical signal and obtains the strain of the outer spiral fiber by measuring the wavelength shift. The data processing module calculates the curvature and torsion of the corresponding fiber deformation based on the strain, and then reconstructs the path of the fiber within the body and determines whether entanglement has occurred using the Frenet-Serret equation geometric shape reconstruction algorithm, thereby achieving real-time spatial shape sensing.

[0067] During the fiber feeding process, the transmitting fiber in the straight fiber bundle of the combined multi-core fiber optic probe module is always in the state of emitting optical signals. If it encounters target tissue, the receiving fiber will receive the optical signal reflected back from the target tissue, and the image is received by the CCD of the imaging module. After the optical signal is modulated by the receiving fiber bundle, the image received by the CCD is a modulation diffraction intensity map. The diffraction intensity map is iteratively recovered by the data processing module according to the quantitative phase imaging algorithm. After the iteration error meets the requirements, the phase information of the detection plane can be obtained. Then, wavefront back diffraction is performed by the angular spectrum transmission equation, which can diffract backward to the target tissue plane and the spatial positions before and after it, thereby calculating the phase information of different planes of the target tissue and realizing the function of three-dimensional imaging. The combined multi-core fiber optic probe structure designed in this invention is as follows: Figure 4 As shown.

[0068] The specific steps of this method are as follows:

[0069] Step 1: The light source module serves as a stable signal source and illumination light source for the optical fiber. The fiber optic fan-in / fan-out module integrates the designed multifunctional composite optical fiber, such as... Figure 2 As shown, the optical signal passes through the entire combined multi-core fiber optic probe module, simultaneously illuminating the target tissue.

[0070] Step 2: When the optical fiber is bent or twisted, the optical fiber will deform, and the grating pitch of the outer spiral grating optical fiber will change accordingly, causing the center wavelength of the signal reflected by the grating to drift. The amount of wavelength change can be detected by the grating demodulator of the shape sensing module.

[0071] Step 3: Calculate fiber strain using the center wavelength shift. The center wavelength shift Δλ and the strain ε have the following relationship:

[0072]

[0073] Where P eλ is the photoelastic coefficient related to the optical fiber material, and λ is the center wavelength of the grating fiber. Since the independent grating fiber at the center of the combined multi-core optical fiber module does not deform during bending and is less affected by temperature because it is wrapped in the fiber bundle, it can be used as a compensation for strain and temperature, thereby eliminating environmental influences and systematic errors.

[0074] Step 4: Calculate fiber curvature using fiber strain. A quantitative relationship also exists between fiber strain and its curvature κ(s), combined with... Figure 5 The following expressions are available:

[0075]

[0076]

[0077] In the above formula, ε i Let r be the axial strain of the i-th fiber. i It is the distance from the i-th fiber to the center of the fiber. In this invention, the fibers are uniformly arranged around the center of the fiber, so r i All are equal, θ b θ is the angle from the bending direction of the optical fiber to the y-axis. i θ is the angle from the i-th fiber to the y-axis. avg ρ is the angle between uniformly distributed optical fibers, and ρ is the radius of curvature. The discrete fiber curvature can be obtained through formulas (2) and (3). By fitting the difference in the fiber bending direction, the continuous curvature function κ(s) can be obtained.

[0078] Step 5: Calculate the fiber deflection using fiber strain. A quantitative relationship also exists between fiber strain and its deflection τ(s), combined with... Figure 6 The following expressions are available:

[0079]

[0080] In the above formula, L p L is the fiber pitch, and L is the original length corresponding to the helical fiber pitch. ε θ is the length after twisting, θ is the twist angle, and r is the distance from the spiral fiber to the center of the fiber.

[0081] The discrete fiber twist angle can be obtained by formula (4). By fitting the difference in the fiber bending direction, the continuous torsion function θ(s) with respect to the arc length s can be obtained.

[0082] τ(s)=θ'(s) (5)

[0083] By differentiating θ(s) from formula (5), the torsion function τ(s) of the optical fiber can be obtained.

[0084] Step 6: Solve the Frenet-Serret equations using curvature and torsion. Substitute the curvature κ(s) and torsion τ(s) into the Frenet-Serret equations:

[0085]

[0086] Where T(s) represents the tangent vector, N(s) represents the normal vector, and B(s) represents the binormal vector. The tangent vector function T(s) is then obtained numerically by calculating the curvature and torsion at each point.

[0087] Step 7: Solve for the fiber shape using the tangent vector function. The curve's function with respect to arc length s can be obtained by calculating the tangent vector function T(s), as shown below:

[0088] r(s)=∫T(s)ds+r0 (7)

[0089] The shape distribution of the optical fiber can be obtained through formula (7), thereby realizing the function of spatial shape perception. Here, r0 represents the initial position of the optical fiber starting point in this coordinate system.

[0090] Step 8: During the fiber feeding process, the transmitting fiber in the straight fiber bundle of the combined multi-core fiber probe module is always in the state of emitting optical signals. When it reaches the vicinity of the target tissue, the receiving fiber in the straight fiber bundle of the combined multi-core fiber probe module will receive the optical signal reflected back by the target tissue. After being modulated by different fibers, the diffraction intensity map is finally acquired by the CCD of the imaging module.

[0091] Step 9: Perform iterative calculations using computational imaging methods to achieve quantitative phase recovery. The diffraction intensity captured by the CCD acquisition surface is light intensity I, and the initial guess of the phase of the acquisition surface is... The iterative process is as follows: (n represents the nth iteration, Indicates forward transmission. (Indicates reverse transmission)

[0092] 1) Perform an initial estimation of the sampling surface, assuming its distribution is as follows: i is the imaginary unit;

[0093] 2) Backpropagation to the target tissue plane yields the target tissue plane distribution. And perform planar constraints;

[0094] 3) Propagate forward from the target tissue plane to the collection surface to obtain the collection surface distribution.

[0095] 4) Perform acquisition plane constraints to maintain phase. The calculated amplitude remains unchanged, and is replaced with the square root of the recorded intensity.

[0096] 5) Backpropagation from the recording plane to the sample plane

[0097] 6) Determine if convergence has occurred. If the error is less than the set value, output the result; if it is greater, perform sample plane constraints, update using the HIO algorithm, and proceed to the next iteration.

[0098]

[0099] In the formula, q is the object plane coordinate system, and Q represents e. n 'The set of points in the region that does not satisfy the spatial constraints, where ε∈[0.5,1] is a constant.

[0100] Its transmission process generally uses angular spectrum transmission, as shown in formula (9):

[0101] A(ξ,η)=A0(ξ,η)H(ξ,η) (9)

[0102] In the formula, ξ and η are spatial frequency components, A(ξ,η) and A0(ξ,η) are the input and output spectra of the system, and H(ξ,η) is the angular spectral transfer factor.

[0103]

[0104] In the formula, z is the transmission distance, λ is the wavelength, k is the wave number, and j is the imaginary unit.

[0105] Step 10: Calculate the phase information of the target tissue plane and its spatial positions before and after it. After step 9, the phase information of the acquisition plane can be calculated. Then, through angular spectrum transmission, it is back-diffracted to the target tissue plane and its spatial positions before and after it to recover the phase information of multiple planes, thereby achieving the purpose of three-dimensional imaging. At the same time, the position information obtained by spatial shape perception can be fused with the three-dimensional imaging information to achieve the purpose of visualization.

[0106] The above embodiments are based on a spatial shape sensing and three-dimensional imaging device and method using multi-core optical fibers. Two functions can be simultaneously achieved using a single bundle of multi-core optical fibers: spatial shape sensing and three-dimensional imaging. The outer spiral grating fiber bundle of this invention can detect the curvature and torsion of the fiber through fiber deformation, and then reconstruct the spatial shape based on a spatial curve reconstruction algorithm. Traditional endoscopic imaging typically only performs two-dimensional imaging, while this invention, using computational imaging technology, directly recovers the phase information of the target tissue through iterative calculation based on the received diffraction image. Furthermore, through wavefront inversion technology, three-dimensional imaging of the target tissue can be achieved. Simultaneously, spatial information and imaging information at different times are fused to achieve visual representation. This invention only requires a single, specially designed fiber bundle to achieve both functions; the diameter of the designed fiber bundle is on the order of micrometers.

[0107] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made according to the purpose of the invention. Any changes, modifications, substitutions, combinations or simplifications made based on the spirit and principle of the technical solution of the present invention shall be equivalent substitutions. As long as they meet the purpose of the invention and do not deviate from the technical principle and inventive concept of the method for spatial shape perception and three-dimensional imaging based on combined multi-core optical fibers, they shall fall within the protection scope of the present invention.

Claims

1. A multi-core fiber-based spatial shape sensing and three-dimensional imaging apparatus, comprising: The device includes: a light source module, a fiber optic fan-in / fan-out module, a combined multi-core fiber optic probe module, a shape sensing module, an imaging module, and a data processing module; wherein... The light source module transmits optical signals to the optical fiber and provides illumination light for imaging. The fiber optic fan-in / fan-out module is used to integrate the optical fibers of different modules into a single bundle, and connects the shape sensing module and the imaging module. The combined multi-core fiber optic module is mainly divided into two parts. One part is connected to the shape sensing module through the fiber fan-in and fan-out modules for shape perception; the other part is connected to the imaging module through the fiber fan-in and fan-out modules for three-dimensional imaging. The shape sensing module, which includes a grating demodulator, is connected to the outer spiral fiber of the multi-core fiber module through the fiber fan-in and fan-out modules to convert the received center wavelength drift into strain. The imaging module, which includes a CCD camera, is connected to the receiving fiber of the straight fiber bundle of the fiber fan-in and fan-out module and the multi-core fiber module to receive the diffraction image modulated by the multi-core fiber. The data processing module, including a computer, converts the strain detected by the shape sensing module into a three-dimensional shape to achieve spatial shape perception; it performs quantitative phase recovery on the diffraction image received by the imaging module to achieve target tissue imaging; and it fuses the fiber position at different times with the three-dimensional image to achieve real-time visualization. The multi-core fiber consists of two parts. The first part consists of multiple outer spiral fibers and a central independent fiber. This part of the fiber is engraved with a grating. The outer spiral fibers are used for strain and spatial sensing, and the central independent fiber is used for temperature and strain compensation. The second part consists of two straight fiber bundles wrapped around the central independent fiber, without grating. One layer is a transmitting fiber for emitting illumination light, and the other layer is a receiving fiber for receiving the object light reflected back from the target tissue.

2. The multicore fiber-based spatial shape perception and three-dimensional imaging apparatus according to claim 1, characterized by, The following steps outline the implementation of a spatial shape sensing and 3D imaging method based on multi-core optical fibers: Step 1: The light source module serves as the stable signal source and illumination light for the optical fiber, while the fiber fan-in and fan-out modules integrate the designed multifunctional combined optical fibers; the optical signal passes through the entire combined multi-core fiber probe module, simultaneously illuminating the target tissue; Step 2: When the optical fiber is bent or twisted, the optical fiber will deform, and the grating pitch of the outer spiral grating optical fiber will change accordingly, causing the center wavelength of the signal reflected by the grating to drift. The amount of wavelength change can be detected by the grating demodulator of the shape sensing module. Step 3: Calculate the fiber strain by the amount of central wavelength shift, Δλ and strain have the following relationship: (1)； in It is the photoelastic coefficient related to optical fiber materials. λ It is the center wavelength of the grating fiber; since the independent grating fiber in the center of the combined multi-core fiber module does not deform during bending, and is also less affected by temperature when wrapped in the fiber bundle, it serves as a compensation for strain and temperature, thereby eliminating environmental influences and system errors. Step 4: Calculate fiber curvature using fiber strain; fiber strain and its curvature There is also a quantitative relationship between them, expressed as follows: (2)； (3)； In the above formula For the first i Axial strain of the optical fiber, It is the first i The distance from the root fiber to the center of the fiber; the fibers are evenly distributed around the center of the fiber, therefore... All are equal. It is the angle from the bending direction of the optical fiber to the y-axis. It is the first i The angle of the fiber to the y-axis It is the angle between uniformly distributed optical fibers. ρ The radius of curvature; By formula (2) (3) that is to get discrete fiber curvature, by fitting the difference in the fiber bending direction, get continuous curvature function ; Step 5: Calculate fiber deflection using fiber strain; fiber strain and its deflection There is also a quantitative relationship between them, expressed as follows: (4)； In the above formula is the fiber pitch, L is the original length corresponding to the helical fiber pitch, is the length after twisting, θ is the twist angle, r is the distance from the helical fiber to the fiber center; The discrete fiber twist angle can be obtained by equation (4), and the continuous curvature function about the arc length s can be obtained by fitting the difference of the fiber bending direction s ;​ (5)； According to equation (5) on the differential, i.e. the deflection function of the optical fiber ; Step 6: Solve the Frenet-Serret equation using curvature and torsion; convert curvature... and torsion Substituting into the Frenet-Serret equation: (6)； wherein, denotes the tangent vector, denotes the normal vector, denotes the binormal vector; the tangent vector function is then obtained numerically from the curvature and torsion of the curve through the points Step 7: Solve the fiber shape by the tangent vector function; solve the fiber shape by the tangent vector function The curve is calculated as r The function of the arc length s is as follows: (7)； By formula (7), the shape distribution of the optical fiber can be obtained, thereby realizing the function of spatial shape sensing. Wherein, represents the initial position of the starting point of the optical fiber in the local coordinate system; Step 8: During the fiber feeding process, the transmitting fiber in the straight fiber bundle of the combined multi-core fiber probe module is always in the state of emitting light signals. When it reaches the vicinity of the target tissue, the receiving fiber in the straight fiber bundle of the combined multi-core fiber probe module will receive the light signal reflected back by the target tissue. After being modulated by different fibers, the diffraction intensity map is finally acquired by the CCD of the imaging module. Step 9: Quantitative phase retrieval is performed using an iterative computation method; the diffraction intensity captured by the CCD collection plane is the light intensity I , the initial guess phase of the collection plane is ; the iterative process is as follows: 1) An initial estimate is made of the acquisition surface, assuming it to be distributed as , i is the imaginary unit; 2) back propagation to the target tissue plane to get the target tissue plane distribution and plane constraint; 3) Forward propagation from the target tissue plane to the acquisition plane to get the acquisition plane distribution ; 4) Collecting plane constraint is applied, keeping phase unchanged, replacing the calculated amplitudes with the recorded square roots of intensity ; 5) Propagating from the recording plane back to the sample plane ; 6) Determine if convergence has occurred. If the error is less than the set value, output the result; if it is greater, perform sample plane constraints, update using the HIO algorithm, and proceed to the next iteration. (8)； In the formula q is the object plane coordinate system, represents The point set in the middle does not satisfy the spatial constraint, is a constant; n represents the nth iteration, represents forward transmission, represents reverse transmission; its transmission process uses angular spectrum transmission method.

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