Device and method for calibrating submillimeter surgical instrument head end force sensor based on FBG (Fiber Bragg Grating)

Abstract

The invention discloses a calibration device and method of a submillimeter surgical instrument head end force sensor based on an FBG (Fiber Bragg Grating). The device comprises a computer, a positioning plate, an XYZ-direction precision linear sliding table, an XY-direction BOTA supporting table, a BOTA force sensor contact, a BOTA force sensor, an FBG force sensor, an FBG force sensor clamp, an FBG force sensor supporting table, an R-direction rotary sliding table, a Z-direction large-range linear sliding table, an FBG demodulator and a Z-direction BOTA supporting table. The method is realized by adopting the calibration device of the submillimeter surgical instrument head end force sensor based on the FBG. Complete decoupling of the three-dimensional force and the temperature is achieved on the calibration mechanism, and the dimension limitation of traditional calibration is broken through. The R-direction rotary sliding table is used for driving the optical fiber sensor to rotate, the lateral force calibration process is greatly simplified, and mechanical errors and operation difficulty are remarkably reduced. According to the invention, low-cost full-dimension high-precision calibration is realized.

Description

Technical Field

[0001] This invention belongs to the fields of minimally invasive medical devices and fiber optic sensing technology, specifically a calibration device and method for a submillimeter surgical instrument tip force sensor based on FBG. Background Technology

[0002] Cardiovascular and cerebrovascular diseases have become one of the major threats to human health. Minimally invasive vascular interventional surgery, due to its advantages such as rapid recovery and minimal trauma, has become the mainstream treatment for these diseases. With the rapid development of medical robot technology, vascular interventional surgical robots are gradually being applied in clinical practice, assisting doctors in performing high-precision guidewire and catheter operations, effectively reducing the exposure time of medical staff under X-rays. However, most existing vascular interventional surgical robots adopt a "master-slave" operation mode. Although this achieves physical isolation between the doctor and the patient, it also cuts off the doctor's direct perception of the contact force at the end of the guidewire. In complex and tortuous vascular pathways, the lack of distal force tactile feedback can easily lead to doctors being unable to accurately judge the contact state between the instrument and the vessel wall, increasing the risk of intraoperative complications such as vascular perforation and dissection, and seriously restricting the safety and popularization of surgical robots.

[0003] To address these challenges, the development of force sensors with sub-millimeter dimensions that can be integrated into the tips of surgical instruments has become a research hotspot. Among numerous sensing technologies, fiber Bragg grating (FBG) sensors, with their inherent advantages such as tiny diameter (down to the micrometer level), resistance to electromagnetic interference, good biocompatibility, and high sensitivity, are considered an ideal solution for force sensing of minimally invasive intravascular instruments. By integrating an FBG sensor array into the tip of a guidewire or catheter, it is theoretically possible to achieve real-time monitoring of the three-dimensional contact force at the instrument tip, providing physicians with crucial tactile navigation information.

[0004] Despite the proliferation of FBG-based miniature force sensor designs, calibration techniques for sub-millimeter-scale FBG force sensors still face numerous challenges. First, there's the alignment difficulty caused by size effects: interventional surgical instruments (such as guidewires) are typically less than 1 millimeter in diameter. Applying standardized three-dimensional force loads on such a tiny scale places extremely high demands on the mechanical precision and clamping stability of the calibration device. Conventional large-scale mechanical testing platforms struggle to achieve micrometer-level alignment fine-tuning, easily leading to calibration errors due to alignment deviations. Second, there's the issue of cross-sensitivity: FBG sensors are sensitive to both strain and temperature. During interventional procedures, changes in blood temperature directly cause wavelength drift, interfering with force measurement results. Existing calibration methods often involve simple mechanical testing under isothermal conditions, lacking integrated temperature compensation calibration, resulting in distorted measurement data under actual varying temperature environments. Finally, there is the limitation of calibration dimensions: most existing micro-sensor calibration devices can only perform simple loading in one direction or two-dimensional planes (e.g., Shi C, Li T, Ren H. AMillinewton Resolution Fiber Bragg Grating-Based Catheter Two-Dimensional Distal Force Sensor for Cardiac Catheterization [J]. IEEE Sensors Journal, 2018, 18(4): 1539-1546.), making it difficult to simulate the complex forces acting on guidewires from various directions within blood vessels. The lack of a comprehensive multi-dimensional calibration matrix results in insufficient accuracy of the sensor's decoupling algorithm in actual three-dimensional space, failing to meet the high-precision force feedback requirements of clinical surgery.

[0005] Therefore, there is an urgent need for a calibration device and method for an FBG force sensor specifically designed for the tip of sub-millimeter surgical instruments, which integrates high-precision multi-dimensional displacement adjustment and temperature compensation functions. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a calibration device and method for a submillimeter surgical instrument tip force sensor based on FBG.

[0007] The technical solution of the present invention to solve the technical problem of the device is to provide a calibration device for a submillimeter surgical instrument tip force sensor based on FBG, characterized in that the device includes a computer, a positioning plate, an XYZ precision linear slide, an XY BOTA support, a BOTA force sensor contact, a BOTA force sensor, an FBG force sensor, an FBG force sensor fixture, an FBG force sensor support, an R-axis rotary slide, a Z-axis large-range linear slide, an FBG demodulator, and a Z-axis BOTA support; The housing of the XYZ precision linear slide is fixed to the positioning plate. The XY-axis BOTA support or the Z-axis BOTA support is detachably fixed to the output end of the XYZ precision linear slide. This is used to achieve small-range precision adjustment of the BOTA force sensor in the XY or Z directions when calibrating the FBG force sensor in the XY or Z directions. The BOTA force sensor is fixed to the XY-axis BOTA support or the Z-axis BOTA support and is used to measure the standard force value of the FBG force sensor in different directions. The BOTA force sensor contact is set on the BOTA force sensor. The housing of the Z-axis large-range linear slide is fixed to the positioning plate and is used for coarse adjustment of the FBG force sensor position in the Z-axis large range. The housing of the R-axis rotary slide is fixed to the output end of the Z-axis large-range linear slide and is used for adjusting the angle of the FBG force sensor. The FBG force sensor support is fixed to the output end of the R-axis rotary slide and can rotate along the R-axis rotary slide. The FBG force sensor fixture is fixed to the FBG force sensor support. The FBG force sensor is detachably fixed in the FBG force sensor fixture. The FBG force sensor is connected to the FBG demodulator, which demodulates the center wavelength drift of the FBG force sensor when subjected to forces in different directions and temperature changes. The computer is connected to both the FBG demodulator and the BOTA force sensor.

[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention utilizes an R-axis rotating slide to drive the fiber optic sensor to rotate, greatly simplifying the lateral force calibration process and significantly reducing mechanical errors and operational difficulty. For sub-millimeter-level (e.g., 360μm diameter) guidewires and their tip force sensors, this invention innovatively completes the full-cycle lateral calibration by rotating the FBG force sensor in conjunction with high-precision vertical loading of the BOTA force sensor along the Z-axis. This design completely solves the cumbersome problem of repeatedly fine-tuning the X / Y position of the BOTA force sensor to find the main direction of the FBG in traditional methods, avoiding the cumulative error introduced by multi-dimensional adjustments. Through the strategy of "rotation instead of movement", high-efficiency and high-precision calibration is achieved.

[0009] (2) This invention achieves complete decoupling of three-dimensional force and temperature in the calibration mechanism, breaking through the dimensional limitations of traditional calibration. Unlike existing technologies that only calibrate two-dimensional forces or general resultant forces, this invention fully considers three-dimensional forces (F... x ,F y ,F zThe coupling effect between force and temperature was investigated. By integrating a thermostatic control element into the mechanical calibration, a four-dimensional decoupling model (three-dimensional force + temperature) was constructed, incorporating the temperature dimension. This not only effectively acquires the independent component forces in three directions but also eliminates the interference of intraoperative temperature changes on the force sensor, ensuring the authenticity of the force feedback data and the reliability of the decoupling matrix.

[0010] (3) This invention is specifically designed for the micrometer scale and effectively solves the problem of clamping and alignment of flexible micro-devices. A special fixture integrating "clamping plate-support-protrusion" is designed, which, together with a multi-stage slide system, realizes the stable clamping and contact positioning of the sub-millimeter flexible guide wire end force sensor. This special rotary calibration structure, combined with a temperature compensation mechanism, is adapted to the clamping requirements of micro-sized sensors and effectively eliminates the calibration deviation caused by misalignment during installation.

[0011] (4) This invention achieves low-cost, high-precision calibration across all dimensions. Through simple platform switching (XY / Z-axis BOTA platform), three-dimensional force data acquisition can be completed using only one device. This invention eliminates environmental interference and installation errors through the organic combination of high-precision displacement adjustment, rotation mechanism, and temperature control, providing a low-cost, high-reliability solution for the development of force sensing modules in vascular interventional robots. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of the calibration device of the present invention during XY direction calibration; Figure 2 This is a schematic diagram of the overall structure of the calibration device of the present invention during Z-axis calibration; Figure 3 This is a schematic diagram of the FBG force sensor fixture of the present invention; Figure 4 This is a schematic diagram of the FBG force sensor of the present invention; Figure 5 This is a cross-sectional schematic diagram of the FBG force sensor of the present invention.

[0013] In the diagram, 1 is a computer, 2 is a positioning plate, 3 is a Y-axis precision linear slide, 4 is an X-axis precision linear slide, 5 is a Z-axis precision linear slide, 6 is an XY-axis BOTA support, 7 is a BOTA force sensor contact, 8 is a BOTA force sensor, 9 is an FBG force sensor, 10 is an FBG force sensor fixture, 11 is an FBG force sensor support, 12 is an R-axis rotary slide, 13 is a Z-axis large-range linear slide, 14 is an FBG demodulator, and 15 is a Z-axis BOTA support. 9.1 Sensor ball head, 9.2 Encapsulation shell, 9.3 Sensor fixing structure, 9.4 Medical guide wire, 9.5 First FBG, 9.6 Second FBG, 9.7 Third FBG, 9.8 Fourth FBG, 10.1 Boss structure, 10.2 Support structure, 10.3 Clip structure. Detailed Implementation

[0014] Specific embodiments of the present invention are given below. These specific embodiments are only used to further illustrate the present invention in detail and do not limit the scope of protection of the present invention.

[0015] This invention provides a calibration device (hereinafter referred to as the device) for a submillimeter surgical instrument tip force sensor based on FBG. The device is characterized by comprising a computer 1, a positioning plate 2, an XYZ precision linear slide, an XY BOTA support 6, a BOTA force sensor contact 7, a BOTA force sensor 8, an FBG force sensor 9, an FBG force sensor clamp 10, an FBG force sensor support 11, an R-axis rotary slide 12, a Z-axis large-range linear slide 13, an FBG demodulator 14, and a Z-axis BOTA support 15. The housing of the XYZ precision linear slide is fixed to the positioning plate 2. The XY BOTA support 6 or the Z BOTA support 15 is detachably fixed to the output end of the XYZ precision linear slide by bolts. It is used to achieve small-range precision adjustment of the BOTA force sensor 8 in the XY or Z direction when calibrating the FBG force sensor 9. The BOTA force sensor 8 is fixed to the XY BOTA support 6 or the Z BOTA support 15 by bolts. It is used to measure the standard force value of the FBG force sensor 9 in different directions. The BOTA force sensor contact 7 is set on the BOTA force sensor 8. The housing of the Z-axis large-range linear slide 13 is fixed to the positioning plate 2 for coarse Z-axis large-range adjustment of the position of the FBG force sensor 9 on its side; the housing of the R-axis rotary slide 12 is fixed to the output end of the Z-axis large-range linear slide 13 for adjusting the rotation angle of the FBG force sensor 9 on its side; the FBG force sensor support 11 is fixed to the output end of the R-axis rotary slide 12 by bolts and can rotate along the R-axis rotary slide 12; the FBG force sensor clamp 10 is detachably fixed to the FBG force sensor support 11; the FBG force sensor 9 is detachably fixed in the FBG force sensor clamp 10; the FBG force sensor 9 is communicatively connected to the FBG demodulator 14, and the FBG demodulator 14 demodulates the center wavelength drift of the FBG force sensor 9 when subjected to forces in different directions and temperature changes; Computer 1 is connected to FBG demodulator 14 and BOTA force sensor 8 for communication.

[0016] Preferably, the XYZ precision linear slide is composed of a Y-axis precision linear slide 3, an X-axis precision linear slide 4, and a Z-axis precision linear slide 5; the Y-axis precision linear slide 3, the X-axis precision linear slide 4, and the Z-axis precision linear slide 5 are connected in sequence, the housing of the lowest slide is fixed on the positioning plate 2, and the output end of the uppermost slide is fixed with an XY-axis BOTA support 6 or a Z-axis BOTA support 15; In this embodiment, the housing of the Y-axis precision linear slide 3 is fixed to the positioning plate 2; the housing of the X-axis precision linear slide 4 is fixed to the output end of the Y-axis precision linear slide 3 and moves with the output end of the Y-axis precision linear slide 3; the housing of the Z-axis precision linear slide 5 is fixed to the output end of the X-axis precision linear slide 4 and moves with the output end of the X-axis precision linear slide 4; the XY-axis BOTA support 6 or the Z-axis BOTA support 15 is fixed to the output end of the Z-axis precision linear slide 5 and moves with the output end of the Z-axis precision linear slide 5.

[0017] Preferably, the X-axis precision linear slide 4 and the Y-axis precision linear slide 3 both have a movement range of ±6.5mm and an accuracy of 0.01mm; the Z-axis precision linear slide 5 has a movement range of 10mm and an accuracy of 0.01mm; the R-axis rotary slide 12 has a coarse adjustment movement range of 360° and a coarse adjustment accuracy of 1°, a fine adjustment movement range of 5° and a fine adjustment accuracy of 0.003°; and the Z-axis large-range linear slide 13 has a movement range of 160mm and an accuracy of 1mm.

[0018] Preferably, the BOTA force sensor 8 uses serial communication; F x and F y All have a measuring range of 80N and an accuracy of 150mN; F z Its range is 100N and its accuracy is 100mN.

[0019] Preferably, the FBG force sensor 9 includes a sensor ball head 9.1, an encapsulation shell 9.2, a sensor fixing structure 9.3, a medical guide wire 9.4, a first FBG 9.5, a second FBG 9.6, a third FBG 9.7, and a fourth FBG 9.8; The medical guidewire 9.4 is disposed in the central hole of the encapsulation shell 9.2; the initial center wavelengths of the first FBG 9.5 and the third FBG 9.7 are the same; the initial center wavelengths of the second FBG 9.6 and the fourth FBG 9.8 are the same; the first FBG 9.5, the second FBG 9.6, the third FBG 9.7, and the fourth FBG 9.8 are respectively disposed in the four FBG holes around the encapsulation shell 9.2; adjacent FBGs are spaced 90° apart, and each FBG is equidistant from the central medical guidewire 9.4 (i.e., all FBGs are located on the same circumference); the first FBG 9.5, the second FBG 9.6, the third FBG 9.7, and the fourth FBG 9.8 are respectively disposed in the four FBG holes around the encapsulation shell 9.2; ...7, and the fourth FBG 9.8 are respectively disposed in the four FBG holes around the encapsulation shell 9.2; the first FBG 9.5 The tips of the first FBG 9.5, the second FBG 9.6, the third FBG 9.7, the fourth FBG 9.8, the medical guidewire 9.4, and the encapsulation shell 9.2 are aligned and fixed to form the sensor ball head 9.1; the tail ends of the first FBG 9.5, the second FBG 9.6, the third FBG 9.7, the fourth FBG 9.8, the medical guidewire 9.4, and the encapsulation shell 9.2 are fixed to form the sensor fixing structure 9.3; the first FBG 9.5, the second FBG 9.6, the third FBG 9.7, and the fourth FBG 9.8 are communicatively connected to the FBG demodulator 14. Preferably, the diameter of the medical guidewire 9.4 is 360 μm; the diameters of the first FBG 9.5, the second FBG 9.6, the third FBG 9.7, and the fourth FBG 9.8 are all 150 μm; the initial center wavelengths of the first FBG 9.5 and the third FBG 9.7 are both 1535 nm; the initial center wavelengths of the second FBG 9.6 and the fourth FBG 9.8 are both 1550 nm; and the diameter of the encapsulation shell 9.2 is 800 μm, with five through holes distributed on it, the center being the medical guidewire hole and the surrounding FBG holes.

[0020] Preferably, the FBG force sensor fixture 10 includes a boss structure 10.1, a support structure 10.2, and a clamping structure 10.3; The boss structure 10.1 is detachably fixed in the slot hole of the FBG force sensor support 11 to provide positioning and complete fixation on the FBG force sensor support 11, thereby fixing the FBG force sensor 9; the support structure 10.2 is used to connect the clamping structure 10.3 and the boss structure 10.1; a 1.8mm through hole is formed at the axis of the clamping structure 10.3 to ensure the normal insertion of the FBG force sensor 9; the clamping structure 10.3 is used to tighten the FBG force sensor 9 with bolts and nuts inserted in the hole when the FBG force sensor 9 extends 3.2~4mm (preferably 3.5mm) in length.

[0021] Preferably, the FBG demodulator 14 uses UDP network communication, with a demodulation wavelength range of 1521~1568nm, an accuracy of 1pm, and 4 channels. The function of the FBG demodulator 14 is to transmit optical signals into the four FBGs of the FBG force sensor 9, receive the physical information of light reflection, and transmit it to the computer 1 through calculation.

[0022] This invention also provides a calibration method (hereinafter referred to as the method) for a submillimeter surgical instrument tip force sensor based on FBG, characterized in that the method is implemented using the aforementioned calibration device for the submillimeter surgical instrument tip force sensor based on FBG, and includes the following steps: Step 1: Insert the medical guidewire 9.4 into the center hole of the encapsulation shell 9.2; insert the first FBG 9.5, the second FBG 9.6, the third FBG 9.7, and the fourth FBG 9.8 into the encapsulation shell 9.2, with adjacent FBGs spaced 90° apart and all four FBGs located on the same circumference; align the tips of the first FBG 9.5, the second FBG 9.6, the third FBG 9.7, the fourth FBG 9.8, the medical guidewire 9.4, and the encapsulation shell 9.2. Step 2: Fix the tail ends of the first FBG 9.5, the second FBG 9.6, the third FBG 9.7, the fourth FBG 9.8, the medical guide wire 9.4, and the encapsulation shell 9.2 to form the sensor fixing structure 9.3; then place the whole thing vertically and solidify to form the sensor ball head 9.1, thus obtaining the FBG force sensor 9. Preferably, step 2 specifically involves: using pointed tweezers to apply an appropriate amount of light-curing adhesive to the tail end of the encapsulation shell 9.2, and then using ultraviolet light to irradiate and solidify it, thereby fixing the tail ends of the first FBG 9.5, the second FBG 9.6, the third FBG 9.7, the fourth FBG 9.8, the medical guide wire 9.4, and the encapsulation shell 9.2 to form the sensor fixing structure 9.3; then placing the whole structure vertically, applying an appropriate amount of light-curing adhesive to the head end of the encapsulation shell 9.2, allowing it to naturally form a ball head, and then using ultraviolet light to irradiate and solidify it to form the sensor ball head 9.1.

[0023] Step 3: Insert the FBG force sensor 9 into the FBG force sensor fixture 10, and make the head of the FBG force sensor 9 protrude from the outside of the FBG force sensor fixture 10, and then fix the FBG force sensor 9; then load the FBG force sensor fixture 10 into the FBG force sensor support 11, and tighten the bolts to fix the FBG force sensor fixture 10. Preferably, in step 3, the head of the FBG force sensor 9 protrudes 3.2~4mm outside the FBG force sensor clamp 10, and then the bolts are tightened to secure the FBG force sensor 9.

[0024] Step 4: Adjust the Z-axis large-range linear slide 13 so that the head end of the FBG force sensor 9 is close to the spherical head end of the BOTA force sensor contact 7; then fine-tune the X-axis precision linear slide 4 and the Y-axis precision linear slide 3 so that the spherical head end of the BOTA force sensor contact 7 is directly above the head end of the FBG force sensor 9; then fine-tune the Z-axis precision linear slide 5 until the spherical head end of the BOTA force sensor contact 7 contacts the head end of the FBG force sensor 9, and then demodulate the Δλ.i The contact status between the spherical tip of the BOTA force sensor contact 7 and the tip of the FBG force sensor 9 is determined by the values ​​(i=1,2,3,4). The adjustment ends when Δλ1, Δλ2, Δλ3, and Δλ4 are all exactly 0. At this point, the spherical tip of the BOTA force sensor contact 7 is in contact with the tip of the FBG force sensor 9 but is not under force. Δλ1, Δλ2, Δλ3, and Δλ4 are the center wavelength drifts of the first FBG 9.5, the second FBG 9.6, the third FBG 9.7, and the fourth FBG 9.8, respectively. Step 5: While continuously rotating the R-axis rotary slide 12, fine-tune the Z-axis precision linear slide 5 to apply force to the head end of the FBG force sensor 9. When Δλ1 and Δλ3 are opposites and Δλ1 is positive, and Δλ2 and Δλ4 are the same, and Δλ1, Δλ2, Δλ3 and Δλ4 are all within the drift range of -10pm to 10pm, the spherical head end of the BOTA force sensor contact 7 is just above the first FBG9.5 of the FBG force sensor 9, thus completing the positioning of the first FBG9.5. Step 6: After the first FBG9.5 is positioned, the F of the BOTA force sensor 8 is... z The absolute value of F is used as the force sensor 9's F value at this time. x The value is then assigned a plus sign (+) before it, denoted as F. x +, to obtain a set (F) x +, Δλ1, Δλ2, Δλ3, Δλ4) data; provided that Δλ1 and Δλ3 are opposites and Δλ1 is positive, Δλ2 and Δλ4 are the same, and Δλ1, Δλ2, Δλ3 and Δλ4 are all within the drift range of -180pm to 180pm, repeatedly fine-tune the Z-axis precision linear slide 5 to obtain and record at least n-1 sets of F x + and the corresponding Δλ1, Δλ2, Δλ3 and Δλ4, to obtain at least n sets (F x +, Δλ1, Δλ2, Δλ3, Δλ4) data; Step 7: Rotate the R-axis 12-slide table 90°, 180°, and 270° in the same direction (counterclockwise or clockwise), using the method in Step 6, to obtain at least n sets (F y +, Δλ1, Δλ2, Δλ3, Δλ4) data, at least n groups (F x -, Δλ1, Δλ2, Δλ3, Δλ4) data and at least n sets (F y -, Δλ1, Δλ2, Δλ3, Δλ4) data; Preferably, step 7 specifically involves: At position 6, rotate the slide 12 counterclockwise by 90° to position the BOTA force sensor 8. zThe absolute value of F is used as the force sensor 9's F value at this time. y The value is then assigned a plus sign (+) before it, denoted as F. y +, to obtain a set (F) y +, Δλ1, Δλ2, Δλ3, Δλ4) data; provided that Δλ2 and Δλ4 are opposites and Δλ2 is positive, Δλ1 and Δλ3 are the same, and Δλ1, Δλ2, Δλ3 and Δλ4 are all within the drift range of -180pm to 180pm, repeatedly fine-tune the Z-axis precision linear slide 5 to obtain and record at least n-1 sets of F y + and the corresponding Δλ1, Δλ2, Δλ3 and Δλ4, to obtain at least n sets (F y +, Δλ1, Δλ2, Δλ3, Δλ4) data; At position 6, rotate the slide 12 counterclockwise by 180° in the R direction to move the BOTA force sensor 8's F... z The absolute value of F is used as the force sensor 9's F value at this time. x The value is given by adding a minus sign (-) before it, denoted as F. x -, to obtain a set (F) x -, Δλ1, Δλ2, Δλ3, Δλ4) data; provided that Δλ1 and Δλ3 are opposites and Δλ3 is positive, Δλ2 and Δλ4 are the same, and Δλ1, Δλ2, Δλ3 and Δλ4 are all within the drift range of -180pm to 180pm, repeatedly fine-tune the Z-axis precision linear slide 5 to obtain and record at least n-1 sets of F x - and the corresponding Δλ1, Δλ2, Δλ3 and Δλ4, to obtain at least n sets (F x -, Δλ1, Δλ2, Δλ3, Δλ4) data; At position 6, rotate the slide 270° counterclockwise in the R direction to move the BOTA force sensor 8's F... z The absolute value of F is used as the force sensor 9's F value at this time. y The value is given by adding a minus sign before it, denoted as F. y -, to obtain a set (F) y -, Δλ1, Δλ2, Δλ3, Δλ4) data; provided that Δλ2 and Δλ4 are opposites and Δλ4 is positive, Δλ1 and Δλ3 are the same, and Δλ1, Δλ2, Δλ3 and Δλ4 are all within the drift range of -180pm to 180pm, repeatedly fine-tune the Z-axis precision linear slide 5 to obtain and record at least n-1 sets of F y - and the corresponding Δλ1, Δλ2, Δλ3 and Δλ4, to obtain at least n sets (F y -, Δλ1, Δλ2, Δλ3, Δλ4) data; Step 8: Replace the XY-axis BOTA support 6 with the Z-axis BOTA support 15, then adjust the Z-axis large-range linear slide 13 so that the head end of the FBG force sensor 9 is close to the spherical head end of the BOTA force sensor contact 7; then fine-tune the X-axis precision linear slide 4 until the spherical head end of the BOTA force sensor contact 7 contacts the head end of the FBG force sensor 9, and then demodulate the Δλ. i The contact status between the spherical end of the BOTA force sensor contact 7 and the head end of the FBG force sensor 9 is determined by the values ​​(i=1,2,3,4). The adjustment ends when Δλ1, Δλ2, Δλ3 and Δλ4 are all exactly 0. At this time, the BOTA force sensor contact 7 is in contact with the head end of the FBG force sensor 9 but is not under any force. Step 9: Fine-tune the Y-axis precision linear slide 3 and the Z-axis precision linear slide 5 so that the axis of the BOTA force sensor contact 7 is collinear with the axis of the FBG force sensor 9; then fine-tune the X-axis precision linear slide 4 to apply force to the head end of the FBG force sensor 9. When Δλ1, Δλ2, Δλ3 and Δλ4 are all the same negative value and Δλ1, Δλ2, Δλ3 and Δλ4 are all within the drift range of -10pm to 10pm, the BOTA force sensor contact 7 is exactly located at the axis of the medical guide wire 9.4 of the FBG force sensor 9, thus completing the positioning of the medical guide wire 9.4. Step 10: After completing the positioning of the medical guidewire 9.4, place the BOTA force sensor 8's F... z The absolute value of F is used as the force sensor 9's F value at this time. z The value is given by adding a minus sign before it, denoted as F. z -, to obtain a set (F) z -, Δλ1, Δλ2, Δλ3, Δλ4) data; provided that Δλ1, Δλ2, Δλ3, Δλ4 are all the same negative value and Δλ1, Δλ2, Δλ3, and Δλ4 are all within the drift range of -250pm to 20pm, repeatedly fine-tune the X-direction precision linear slide 4 to obtain and record at least n-1 sets of F z - and the corresponding Δλ1, Δλ2, Δλ3 and Δλ4, to obtain at least n sets (F z -, Δλ1, Δλ2, Δλ3, Δλ4) data; Step 11: Remove the FBG force sensor 9 from the FBG force sensor fixture 10 and place it in a variable temperature environment. Record the change in ambient temperature ΔT and the corresponding Δλ1, Δλ2, Δλ3 and Δλ4 for each temperature change, and obtain a set of (ΔT, Δλ1, Δλ2, Δλ3, Δλ4) data. At least n sets of (ΔT, Δλ1, Δλ2, Δλ3, Δλ4) data are obtained in total. Preferably, in step 11, the variable temperature environment is the exhaust port of the electric heating constant temperature chamber. Each temperature change is 0 < T ≤ 5, that is, greater than 0 and less than or equal to 5.

[0025] Preferably, in steps 6 to 11, n=15.

[0026] Step 12: Derivation of the theoretical calibration model for the FBG three-dimensional force sensor: Based on the Euler-Bernoulli beam theory, when the head end of the FBG force sensor 9 is subjected to a lateral force F (i.e., F... x or F y (Sometimes) (1) In equation (1), ε bend y is the radial strain; L is the effective length of the sensing segment; y is the perpendicular distance between the fiber core of the FBG and the neutral axis; E is the Young's modulus of the flexible structure; R is the outer radius of the flexible structure. Based on the composite stiffness model, when the head end of the FBG force sensor 9 is subjected to an axial force F z Sometimes: (2) In equation (2), ε z For axial strain; k fh The axial stiffness of the first FBG9.5, the second FBG9.6, the third FBG9.7, and the fourth FBG9.8; k fl and k gu The axial stiffness of the encapsulation shell 9.2 and the medical guidewire 9.4 are respectively. The formula for the center wavelength shift of FBG is as follows: (3) In equation (3), Δλ i λ represents the center wavelength shift of the first FBG9.5, the second FBG9.6, the third FBG9.7, and the fourth FBG9.8, i=1,2,3,4; i K represents the initial center wavelengths of the first FBG 9.5, the second FBG 9.6, the third FBG 9.7, and the fourth FBG 9.8, where i = 1, 2, 3, 4; ε K is the strain sensitivity coefficient of the optical fiber. ε =1-P e P e K is the effective elastic coefficient. Ti The temperature sensitivity coefficients for the first FBG9.5, second FBG9.6, third FBG9.7, and fourth FBG9.8 are i=1,2,3,4; ΔT is the change in ambient temperature. Based on the formula for the center wavelength shift of FBG, the first FBG 9.5, the second FBG 9.6, the third FBG 9.7, and the fourth FBG 9.8 are at F x F y F z And under the action of ΔT, we have: (4) In equation (4), r is the perpendicular distance between the fiber core of the FBG and the neutral axis in the primary sensing direction; d is the perpendicular distance between the fiber core of the FBG and the neutral axis in the secondary sensing direction; F x F y F z These represent the external forces applied along the x, y, and z axes, respectively. Since the initial center wavelengths of the first FBG9.5 and the third FBG9.7 are the same, and the initial center wavelengths of the second FBG9.6 and the fourth FBG9.8 are the same, the theoretical calibration model of the FBG three-dimensional force sensor is obtained by performing difference and summation on the first FBG9.5 and the third FBG9.7, and the second FBG9.6 and the fourth FBG9.8, respectively, as shown in equation (5). (5) Step 13: Based on the theoretical calibration model of the FBG three-dimensional force sensor obtained in Step 12 and the actual experimental data, solve for the real-time three-dimensional force.

[0027] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A calibration device for a submillimeter surgical instrument tip force sensor based on FBG, characterized in that, The device includes a computer (1), a positioning plate (2), an XYZ precision linear slide, an XY BOTA support (6), a BOTA force sensor contact (7), a BOTA force sensor (8), an FBG force sensor (9), an FBG force sensor fixture (10), an FBG force sensor support (11), an R-axis rotary slide (12), a Z-axis large-range linear slide (13), an FBG demodulator (14), and a Z-axis BOTA support (15). The housing of the XYZ precision linear slide is fixed on the positioning plate (2). The XY BOTA support (6) or Z BOTA support (15) is detachably fixed on the output end of the XYZ precision linear slide. It is used to achieve small-range precision adjustment of the BOTA force sensor (8) in the XY or Z direction when calibrating the FBG force sensor (9). The BOTA force sensor (8) is fixed on the XY BOTA support (6) or Z BOTA support (15) to measure the standard force value of the FBG force sensor (9) in different directions. The BOTA force sensor contact (7) is set on the BOTA force sensor (8). The housing of the Z-axis large-range linear slide (13) is fixed on the positioning plate (2) and is used to make a rough adjustment of the position of the FBG force sensor (9) in the Z-axis large range; the housing of the R-axis rotary slide (12) is fixed on the output end of the Z-axis large-range linear slide (13) and is used to adjust the angle of the FBG force sensor (9); the FBG force sensor support (11) is fixed on the output end of the R-axis rotary slide (12) and can rotate along the R-axis rotary slide (12); the FBG force sensor fixture (10) is fixed on the FBG force sensor support (11); the FBG force sensor (9) is detachably fixed in the FBG force sensor fixture (10); the FBG force sensor (9) is connected to the FBG demodulator (14) for communication, and the FBG demodulator (14) demodulates the center wavelength drift of the FBG force sensor (9) when subjected to different directional forces and temperature changes; The computer (1) is connected to the FBG demodulator (14) and the BOTA force sensor (8) respectively.

2. The calibration device for the FBG-based submillimeter surgical instrument tip force sensor according to claim 1, characterized in that, The XYZ precision linear slide is composed of a Y-axis precision linear slide (3), an X-axis precision linear slide (4), and a Z-axis precision linear slide (5). The Y-axis precision linear slide (3), X-axis precision linear slide (4), and Z-axis precision linear slide (5) are connected in sequence. The housing of the lowest slide is fixed on the positioning plate (2), and the output end of the highest slide is fixed with an XY-axis BOTA support (6) or a Z-axis BOTA support (15).

3. The calibration device for the FBG-based submillimeter surgical instrument tip force sensor according to claim 1, characterized in that, The X-axis precision linear slide (4) and Y-axis precision linear slide (3) have a range of ±6.5 mm and an accuracy of 0.01 mm; the Z-axis precision linear slide (5) has a range of 10 mm and an accuracy of 0.01 mm; the R-axis rotary slide (12) has a coarse adjustment range of 360° and a coarse adjustment accuracy of 1°, a fine adjustment range of 5° and a fine adjustment accuracy of 0.003°; the Z-axis large-range linear slide (13) has a range of 160 mm and an accuracy of 1 mm. BOTA force sensor (8) uses serial communication; F x and F y All have a measuring range of 80N and an accuracy of 150mN; F z The measuring range is 100N, and the accuracy is 100mN. The FBG demodulator (14) uses UDP network communication, and its demodulation wavelength range is 1521~1568nm, with an accuracy of 1pm and 4 channels.

4. The calibration device for the FBG-based submillimeter surgical instrument tip force sensor according to claim 1, characterized in that, The FBG force sensor (9) includes a sensor ball head (9.1), a package shell (9.2), a sensor fixing structure (9.3), a medical guide wire (9.4), a first FBG (9.5), a second FBG (9.6), a third FBG (9.7), and a fourth FBG (9.8). The medical guidewire (9.4) is disposed in the central hole of the encapsulation shell (9.2); the initial center wavelengths of the first FBG (9.5) and the third FBG (9.7) are the same; the initial center wavelengths of the second FBG (9.6) and the fourth FBG (9.8) are the same; the first FBG (9.5), the second FBG (9.6), the third FBG (9.7), and the fourth FBG (9.8) are respectively disposed in the four FBG holes around the encapsulation shell (9.2); the interval between two adjacent FBGs is 90° and the distance between each FBG and the central medical guidewire (9.4) is the same; the first FBG (9.5), the second FBG... (9.6), the head ends of the third FBG (9.7), the fourth FBG (9.8), the medical guide wire (9.4), and the encapsulation shell (9.2) are aligned and fixed to form a sensor ball head (9.1); the tail ends of the first FBG (9.5), the second FBG (9.6), the third FBG (9.7), the fourth FBG (9.8), the medical guide wire (9.4), and the encapsulation shell (9.2) are fixed to form a sensor fixing structure (9.3); the first FBG (9.5), the second FBG (9.6), the third FBG (9.7), and the fourth FBG (9.8) are connected to the FBG demodulator (14) for communication. Preferably, the diameter of the medical guidewire (9.4) is 360 μm; the diameters of the first FBG (9.5), second FBG (9.6), third FBG (9.7) and fourth FBG (9.8) are all 150 μm; the initial center wavelengths of the first FBG (9.5) and third FBG (9.7) are all 1535 nm; the initial center wavelengths of the second FBG (9.6) and fourth FBG (9.8) are all 1550 nm; the diameter of the encapsulation shell (9.2) is 800 μm, and five through holes are distributed on it, with the medical guidewire hole in the center and the FBG holes around it.

5. The calibration device for the FBG-based submillimeter surgical instrument tip force sensor according to claim 1, characterized in that, The FBG force sensor fixture (10) includes a boss structure (10.1), a support structure (10.2), and a clamping structure (10.3). The boss structure (10.1) is detachably fixed in the slot hole of the FBG force sensor support (11) to provide positioning and complete fixation on the FBG force sensor support (11), thereby fixing the FBG force sensor (9); the support structure (10.2) is used to connect the clamping structure (10.3) and the boss structure (10.1); a through hole is formed at the axis of the clamping structure (10.3) to ensure the normal insertion of the FBG force sensor (9); the clamping structure (10.3) is used to fasten the FBG force sensor (9) through the insertion hole when the FBG force sensor (9) extends 3.2~4mm.

6. A calibration method for a submillimeter surgical instrument tip force sensor based on FBG, characterized in that, This method employs the calibration device for the FBG-based submillimeter surgical instrument tip force sensor as described in any one of claims 1-5, and includes the following steps: Step 1: Insert the medical guidewire (9.4) into the center hole of the encapsulation shell (9.2); insert the first FBG (9.5), second FBG (9.6), third FBG (9.7), and fourth FBG (9.8) into the encapsulation shell (9.2), with adjacent FBGs spaced 90° apart and all four FBGs located on the same circumference; align the tips of the first FBG (9.5), second FBG (9.6), third FBG (9.7), fourth FBG (9.8), medical guidewire (9.4), and encapsulation shell (9.2); Step 2: Fix the tail ends of the first FBG (9.5), the second FBG (9.6), the third FBG (9.7), the fourth FBG (9.8), the medical guide wire (9.4), and the encapsulation shell (9.2) to form a sensor fixing structure (9.3); then place the whole vertically and solidify to form a sensor ball head (9.1) to obtain the FBG force sensor (9). Step 3: Insert the FBG force sensor (9) into the FBG force sensor fixture (10) and make the head of the FBG force sensor (9) protrude from the outside of the FBG force sensor fixture (10), and then fix the FBG force sensor (9); then load the FBG force sensor fixture (10) into the FBG force sensor support (11) and fix the FBG force sensor fixture (10). Step 4: Adjust the Z-axis large-range linear slide (13) so that the head end of the FBG force sensor (9) is close to the spherical head end of the BOTA force sensor contact (7); then fine-tune the X-axis precision linear slide (4) and the Y-axis precision linear slide (3) so that the spherical head end of the BOTA force sensor contact (7) is directly above the head end of the FBG force sensor (9); then fine-tune the Z-axis precision linear slide (5) until the spherical head end of the BOTA force sensor contact (7) contacts the head end of the FBG force sensor (9), and then demodulate the Δλ i The contact status between the spherical end of the BOTA force sensor contact (7) and the head end of the FBG force sensor (9) is determined by the values ​​(i=1,2,3,4). The adjustment ends when Δλ1, Δλ2, Δλ3 and Δλ4 are all 0. At this time, the spherical end of the BOTA force sensor contact (7) is in contact with the head end of the FBG force sensor (9) and is not under force. Δλ1, Δλ2, Δλ3 and Δλ4 are the center wavelength drift of the first FBG (9.5), the second FBG (9.6), the third FBG (9.7) and the fourth FBG (9.8), respectively. Step 5: While continuously rotating the R-axis rotary slide (12), finely adjust the Z-axis precision linear slide (5) to apply force to the head end of the FBG force sensor (9). When Δλ1 and Δλ3 are opposites and Δλ1 is positive, and Δλ2 and Δλ4 are the same, and Δλ1, Δλ2, Δλ3 and Δλ4 are all within the drift range of -10pm to 10pm, the spherical head end of the BOTA force sensor contact (7) is just above the first FBG (9.5) of the FBG force sensor (9), thus completing the positioning of the first FBG (9.5). Step 6: After the first FBG (9.5) is positioned, the F of the BOTA force sensor (8) is... z The absolute value of F is taken as the force of the FBG force sensor (9) at this time. x Value, denoted as F x +, to obtain a set (F) x +, Δλ1, Δλ2, Δλ3, Δλ4) data; under the premise that Δλ1 and Δλ3 are opposites and Δλ1 is positive, Δλ2 and Δλ4 are the same, and Δλ1, Δλ2, Δλ3 and Δλ4 are all within the drift range of -180pm to 180pm, the Z-axis precision linear slide (5) is repeatedly fine-tuned to obtain and record at least n-1 sets of F x + and the corresponding Δλ1, Δλ2, Δλ3 and Δλ4, to obtain at least n sets (F x +, Δλ1, Δλ2, Δλ3, Δλ4) data; Step 7: Rotate the slide 12 in the R direction by 90°, 180°, and 270° in the same direction, using the method in Step 6, to obtain at least n sets (F y +, Δλ1, Δλ2, Δλ3, Δλ4) data, at least n groups (F x -, Δλ1, Δλ2, Δλ3, Δλ4) data and at least n sets (F y -, Δλ1, Δλ2, Δλ3, Δλ4) data; Step 8: Replace the XY-direction BOTA stage (6) with the Z-direction BOTA stage (15), and then adjust the Z-direction large-range linear slide (13) so that the head end of the FBG force sensor (9) is close to the spherical head end of the BOTA force sensor contact (7); then fine-tune the X-direction precision linear slide (4) until the spherical head end of the BOTA force sensor contact (7) contacts the head end of the FBG force sensor (9), and then demodulate the Δλ i The contact status between the spherical end of the BOTA force sensor contact (7) and the head end of the FBG force sensor (9) is determined by the values ​​(i=1,2,3,4). The adjustment ends when Δλ1, Δλ2, Δλ3 and Δλ4 are all 0. At this time, the BOTA force sensor contact (7) is in contact with the head end of the FBG force sensor (9) and is not under force. Step 9: Fine-tune the Y-axis precision linear slide (3) and the Z-axis precision linear slide (5) so that the axis of the BOTA force sensor contact (7) is collinear with the axis of the FBG force sensor (9); then fine-tune the X-axis precision linear slide (4) to make the head end of the FBG force sensor (9) bear force. When Δλ1, Δλ2, Δλ3 and Δλ4 are all the same negative value and Δλ1, Δλ2, Δλ3 and Δλ4 are all in the drift range of -10pm to 10pm, the BOTA force sensor contact (7) is just located at the axis of the medical guide wire (9.4) of the FBG force sensor (9), thus completing the positioning of the FBG force sensor (9). Step 10: After completing the positioning of the FBG force sensor (9), place the F of the BOTA force sensor (8)... z The absolute value of F is taken as the force of the FBG force sensor (9) at this time. z Value, denoted as F z -, to obtain a set (F) z -, Δλ1, Δλ2, Δλ3, Δλ4) data; provided that Δλ1, Δλ2, Δλ3, Δλ4 are all the same negative value and Δλ1, Δλ2, Δλ3, and Δλ4 are all within the drift range of -250pm to 20pm, repeatedly fine-tune the X-direction precision linear slide (4) to obtain and record at least n-1 sets of F z - and the corresponding Δλ1, Δλ2, Δλ3 and Δλ4, to obtain at least n sets (F z -, Δλ1, Δλ2, Δλ3, Δλ4) data; Step 11: Remove the FBG force sensor (9) from the FBG force sensor fixture (10) and place it in a variable temperature environment. Record the change in ambient temperature ΔT and the corresponding Δλ1, Δλ2, Δλ3 and Δλ4 for each temperature change T, and obtain a set of (ΔT, Δλ1, Δλ2, Δλ3, Δλ4) data. A total of at least n sets of (ΔT, Δλ1, Δλ2, Δλ3, Δλ4) data are obtained. Step 12: Derivation of the theoretical calibration model for the FBG three-dimensional force sensor: Based on the Euler-Bernoulli beam theory, when the head end of the FBG force sensor (9) is subjected to a transverse force F, we have: （1） In equation (1), ε bend y is the radial strain; L is the effective length of the sensing segment; y is the perpendicular distance between the fiber core of the FBG and the neutral axis; E is the Young's modulus of the flexible structure; R is the outer radius of the flexible structure. Based on the composite stiffness model, when the head end of the FBG force sensor (9) is subjected to an axial force F z Sometimes: （2） In equation (2), ε z For axial strain; k fh denoted as k, representing the axial stiffness of the first FBG (9.5), second FBG (9.6), third FBG (9.7), and fourth FBG (9.8); fl and k gu The axial stiffness of the encapsulation shell (9.2) and the medical guidewire (9.4) are respectively. The formula for the center wavelength shift of FBG is as follows: （3） In equation (3), Δλ i Let λ be the center wavelength shift of the first FBG (9.5), second FBG (9.6), third FBG (9.7), and fourth FBG (9.8), i=1,2,3,4; λ i Let K be the initial center wavelength of the first FBG (9.5), the second FBG (9.6), the third FBG (9.7), and the fourth FBG (9.8), i=1,2,3,4; ε K is the strain sensitivity coefficient of the optical fiber. ε =1-P e P e K is the effective elastic coefficient. Ti The temperature sensitivity coefficients for the first FBG (9.5), second FBG (9.6), third FBG (9.7), and fourth FBG (9.8) are i=1,2,3,4; ΔT is the change in ambient temperature. Based on the formula for the center wavelength drift of the FBG, the first FBG (9.5), the second FBG (9.6), the third FBG (9.7), and the fourth FBG (9.8) are in F x F y F z And under the action of ΔT, we have: （4） In equation (4), r is the perpendicular distance between the fiber core of the FBG and the neutral axis in the primary sensing direction; d is the perpendicular distance between the fiber core of the FBG and the neutral axis in the secondary sensing direction; F x F y F z These represent the external forces applied along the x, y, and z axes, respectively. Since the initial center wavelengths of the first FBG (9.5) and the third FBG (9.7) are the same, and the initial center wavelengths of the second FBG (9.6) and the fourth FBG (9.8) are the same, the first FBG (9.5) and the third FBG (9.7), and the second FBG (9.6) and the fourth FBG (9.8) are respectively differentiated and summed to obtain the theoretical calibration model of the FBG three-dimensional force sensor as shown in equation (5): （5） Step 13: Based on the theoretical calibration model of the FBG three-dimensional force sensor obtained in Step 12 and the actual experimental data, solve for the real-time three-dimensional force.

7. The calibration method according to claim 6, characterized in that, Step 2 is as follows: Use pointed tweezers to apply an appropriate amount of light-curing adhesive to the end of the encapsulation shell (9.2), and use ultraviolet light to irradiate and solidify it, thereby fixing the end of the first FBG (9.5), the second FBG (9.6), the third FBG (9.7), the fourth FBG (9.8), the medical guide wire (9.4), and the encapsulation shell (9.2) to form the sensor fixing structure (9.3); then place the whole thing vertically, apply an appropriate amount of light-curing adhesive to the head of the encapsulation shell (9.2), and after it naturally forms a ball head, use ultraviolet light to irradiate and solidify it to form the sensor ball head (9.1).

8. The calibration method according to claim 6, characterized in that, In step 3, the head of the FBG force sensor (9) protrudes 3.2~4mm outside the FBG force sensor fixture (10).

9. The calibration method according to claim 6, characterized in that, Step 7 specifically involves: At position 6, rotate the slide counterclockwise by 90° (R-direction 12) to move the BOTA force sensor (8) F z The absolute value of F is taken as the force of the FBG force sensor (9) at this time. y The value is then assigned a plus sign (+) before it, denoted as F. y +, to obtain a set (F) y +, Δλ1, Δλ2, Δλ3, Δλ4) data; under the premise that Δλ2 and Δλ4 are opposites and Δλ2 is positive, Δλ1 and Δλ3 are the same, and Δλ1, Δλ2, Δλ3 and Δλ4 are all within the drift range of -180pm to 180pm, the Z-axis precision linear slide (5) is repeatedly fine-tuned to obtain and record at least n-1 sets of F y + and the corresponding Δλ1, Δλ2, Δλ3 and Δλ4, to obtain at least n sets (F y +, Δλ1, Δλ2, Δλ3, Δλ4) data; At position 6, rotate the slide 12 counterclockwise by 180° in the R direction to move the BOTA force sensor (8) F z The absolute value of F is taken as the force of the FBG force sensor (9) at this time. x The value is given by adding a minus sign (-) before it, denoted as F. x -, to obtain a set (F) x -, Δλ1, Δλ2, Δλ3, Δλ4) data; provided that Δλ1 and Δλ3 are opposites and Δλ3 is positive, Δλ2 and Δλ4 are the same, and Δλ1, Δλ2, Δλ3 and Δλ4 are all within the drift range of -180pm to 180pm, the Z-axis precision linear slide (5) is repeatedly fine-tuned to obtain and record at least n-1 sets of F x - and the corresponding Δλ1, Δλ2, Δλ3 and Δλ4, to obtain at least n sets (F x -, Δλ1, Δλ2, Δλ3, Δλ4) data; At position 6, rotate the slide counterclockwise by 270° (R-direction rotation 12) to move the BOTA force sensor (8) F z The absolute value of F is taken as the force of the FBG force sensor (9) at this time. y The value is given by adding a minus sign (-) before it, denoted as F. y -, to obtain a set (F) y -, Δλ1, Δλ2, Δλ3, Δλ4) data; provided that Δλ2 and Δλ4 are opposites and Δλ4 is positive, Δλ1 and Δλ3 are the same, and Δλ1, Δλ2, Δλ3 and Δλ4 are all within the drift range of -180pm to 180pm, the Z-axis precision linear slide (5) is repeatedly fine-tuned to obtain and record at least n-1 sets of F y - and the corresponding Δλ1, Δλ2, Δλ3 and Δλ4, to obtain at least n sets (F y -, Δλ1, Δλ2, Δλ3, Δλ4) data.

10. The calibration method according to claim 6, characterized in that, In step 11, the change in ambient temperature each time is 0 < ΔT ≤ 5; In steps 6 to 11, n=15.

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