Device for measuring pressure fields of four limbs of human body

Abstract

The utility model discloses a human limb pressure field measuring device based on an optical frequency domain reflection technology. The device comprises a tunable laser, a coupler, a circulator, a polarization controller, a photoelectric detector and a high-speed oscilloscope which are connected in sequence. The measuring device has excellent corrosion resistance, high monitoring timeliness and high spatial resolution.

Description

Technical Field

[0001] This utility model relates to fiber optic sensing technology, and more particularly to the measurement of pressure field of human limbs based on optical frequency domain reflection technology, specifically a device for measuring pressure field of human limbs. Background Technology

[0002] With societal progress, people are paying increasing attention to health. Qualitative and quantitative analysis of abnormal distributions in the pressure field of the human limbs can monitor potential deformity risks and enable the development of personalized intervention plans, playing a crucial role in human health management. Furthermore, tailoring sports protection plans to different types of exercise can effectively improve athletic performance. Currently, the measurement of the pressure field in the human limbs mainly relies on technologies such as piezoelectric sensors, strain gauges, and capacitive sensors. However, the discrete point placement of these technologies results in limited spatial resolution, making it difficult to accurately capture the subtle distribution characteristics of the pressure field in the human limbs, especially under complex gait or high dynamic load conditions, where measurement accuracy and stability are significantly limited. In addition, the rigid structure and limited lifespan of piezoelectric sensors also restrict their long-term reliability. Limb pressure field measurement and shape reconstruction based on optical frequency domain reflection distributed fiber optic sensing technology can achieve high-density, continuously distributed pressure measurement with millimeter-level spatial resolution and high sensitivity. It can accurately reconstruct the three-dimensional distribution characteristics of the limb pressure field. This technology not only overcomes the limitations of traditional sensors but also provides more accurate data support for foot biomechanics research, gait analysis, and medical rehabilitation, possessing significant scientific significance and application value. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by providing a pressure field measuring device for the human limbs. This device features excellent electromagnetic interference resistance, high stability, repeatability, high spatial resolution, and a simple structure.

[0004] The technical solution to achieve the purpose of this utility model is:

[0005] A pressure field measurement device for human limbs includes a tunable laser, a coupler, a circulator, a polarization controller, a photodetector, and a high-speed oscilloscope connected in sequence, wherein:

[0006] The entire system is divided into two parts: an external sampling clock unit consisting of a tunable laser, a first fiber coupler, a second fiber coupler, a parallel delay fiber and a single-mode fiber, a fourth fiber coupler, and a first photodetector, connected in sequence, is connected to a high-speed oscilloscope; and a sensor interferometer consisting of a tunable laser, a first fiber coupler, a third fiber coupler, a parallel polarization controller and a fiber circulator, a fifth fiber coupler, a second photodetector, and a test platform, with the output of the second photodetector connected to the high-speed oscilloscope.

[0007] The light output from the tunable laser is split into two paths by the first fiber coupler. One path sequentially passes through the second fiber coupler and enters the parallel delay fiber and single-mode fiber respectively. They are then combined through the fourth fiber coupler and enter the first photodetector to form an external sampling clock unit. The other path sequentially passes through the third fiber coupler and enters the parallel polarization controller and fiber circulator port a respectively. The light exiting from port b of the fiber circulator enters the test platform. The Rayleigh scattering light from the test platform passes through port b of the fiber circulator and enters port c. It then mixes with the light passing through the polarization controller at the fifth fiber coupler and enters the second photodetector to form a sensing optical path unit. The electrical signals from the external sampling clock unit and the sensing optical path unit are acquired and analyzed by a high-speed oscilloscope.

[0008] The test platform is composed of single-mode optical fibers laid out in a flat manner to form a ring-shaped structure with a rectangular shape in the middle and symmetrical semi-circular arcs at both ends. The ring-shaped structure is wound in multiple layers, with n layers. The side lengths of the rectangles are L and the diameters of the semi-circular arcs are R. The single-mode optical fibers on one directional side of all the ring-shaped structures are evenly laid out on the flexible plate, and the spacing between each adjacent optical fiber is R / n.

[0009] All of the above connections are made using FC / APC flanges.

[0010] The tunable laser is model TSL-550, with a tuning range of 1520-1580nm and a tuning speed of 60nm / s.

[0011] The photodetector is model PDB430C, with an operating wavelength of 800~1700nm and a response bandwidth of 350MHz.

[0012] The high-speed oscilloscope is model MSO-S 254A, with a bandwidth of 2.5GHz and a sampling rate of 20GSa / s.

[0013] The splitting ratio of the first fiber coupler to the third fiber coupler is 99%:1%. 1% of the light split from the first fiber coupler enters the external clock through the second fiber coupler, and 99% of the light enters the sensing interferometer through the third fiber coupler. 1% of the light split from the third fiber coupler enters the polarization controller, and 99% of the light split from the third fiber coupler enters the a port of the fiber circulator.

[0014] The splitting ratio of the second, fourth, and fifth fiber couplers is 50%:50%.

[0015] The delay fiber is 200m long and is model SM-28e.

[0016] The linearly swept laser propagation path in this technical solution is as follows: The linearly swept laser emitted by the tunable laser is split into two paths by a first fiber coupler. 1% of the light split from the first fiber coupler is then split into two paths by a second fiber coupler. One path (50%) passes through a delay fiber, and the other (50%) passes through a single-mode fiber. The two paths meet at a fourth fiber coupler and undergo beat frequency interference. The interference signal enters a first photodetector, which converts the interfering optical signal into an electrical signal. The resulting photoelectric signal is acquired by a high-speed oscilloscope as external clock data. The remaining 99% of the light split from the first fiber coupler is then split into two paths by a third fiber coupler. One 1% of the light output passes through the polarization controller to the fifth fiber coupler. The third fiber coupler splits another 99% of the light, which passes through port a of the circulator and enters port b of the circulator for output. The light then enters the test plane. The backscattered Rayleigh light generated by the sensing fiber of the test plane passes through port b of the circulator and enters port c of the circulator for output. The light then enters the fifth fiber coupler. The light output from the polarization controller and the light output from port c of the circulator meet at the fifth fiber coupler and generate a beat frequency interference signal. The second photodetector converts the beat frequency interference optical signal into an electrical signal, which is collected by a high-speed oscilloscope as a sensing signal. The signal from the sensing interferometer is collected by the high-speed oscilloscope and used to reconstruct the distribution of the pressure field of the human limbs.

[0017] The working process of the above-mentioned human limb pressure field measuring device is as follows:

[0018] 1) The laser emitted by the tunable laser enters the first fiber coupler and is split into two beams. One beam enters the sensing optical path unit and the other enters the external clock unit. The beam entering the sensing optical path unit is split into two beams by the third fiber coupler. One beam enters the fiber circulator as the intrinsic beam and the other enters the polarization controller as the reference beam.

[0019] 2) In the sensing interferometer unit, the two beams split from the third fiber coupler enter the polarization controller and then the fifth fiber coupler. The other beam enters the test platform from port a of the fiber circulator. The backscattered Rayleigh light in the test platform passes through port b of the fiber circulator and is transmitted to port c. It converges with the light output from the polarization controller at the fifth fiber coupler and interferes. The second photodetector converts the beat frequency interference light signal into an electrical signal, which is then input to the high-speed oscilloscope. According to the principle of optical heterodyne detection, the 1% signal light and 99% reference light split from the third fiber coupler can be represented as:

[0020] ,

[0021] ,

[0022] in The initial frequency for TLS, This represents the random phase of the reference light. Indicates the delay position Reflectivity This indicates that the Rayleigh backscattered signal is in The random phase at time is coupled to the output signal of the second photodetector through the fifth fiber coupler. for:

[0023] ,

[0024] For two beams of light at time The phase difference;

[0025] 3) In the external clock unit, 1% of the light is split off from the first fiber coupler and enters the second fiber coupler. The second fiber coupler splits the light into two 50%: 50% paths: one path enters the delay fiber and the other path enters the ordinary single-mode fiber. The two paths meet and interfere in the fourth coupler. The interference signal is converted into an electrical signal by the first photodetector and input into the high-speed oscilloscope.

[0026] 4) In the external clock unit, a fixed beat frequency interference signal is generated and acquired by a high-speed oscilloscope. By performing a Fourier transform on the external clock interference signal, its frequency information is extracted and used as a reference to interpolate and resample the data of the sensing optical path unit. This is to solve the nonlinear tuning effect of the laser emitted by the tunable light source, so that the acquired signal of the sensing interferometer unit is more accurate.

[0027] 5) In the sensing interferometer unit, keep the test platform stationary and unloaded, and collect the backscattered Rayleigh spectral signal as a reference signal;

[0028] 6) In the sensing interferometer unit, when the human limbs are in flat contact with the test platform, the pressure will cause the backscattering Rayleigh signal of the optical fiber on the test platform to change. The backscattering Rayleigh spectral signal is collected as the sensing signal.

[0029] 7) The cross-correlation algorithm is used to analyze the Rayleigh scattering spectrum drift of the reference signal and the sensor signal to obtain the pressure distribution information on the optical fiber of the test platform. The beat frequency signal representing the two beams of light, which varies linearly with time, is the correlation function of the position of the scattering point on the test plane optical fiber, and is written as:

[0030] ,

[0031] Where x represents the position of the scattering point on the test plane fiber, n is the refractive index of the test plane fiber, and c is the speed of light in a vacuum. When the TLS performs a linear scan, scattering points at different positions on the test plane fiber correspond to different frequencies. The original OFDR signal is transformed to the frequency domain using a Fourier transform, and the position of the scattering point on the test plane fiber is derived based on the frequency of the spectrum, thus achieving fiber positioning. If the scan period is set to T, according to the properties of the Fourier transform, the frequency resolution of the system is... The theoretical spatial resolution can be expressed as:

[0032] ,

[0033] in This refers to the wavelength tuning range of the tunable laser. N data points at the same length are used as a sliding window W. When taking values ​​in the next sliding window, 80% of the data is repeated from the previous sliding window. In this case, the spatial resolution is 0.2 times the length of the sliding window. The length represented by the sliding window is:

[0034] ;

[0035] By matching the data windows of the reference signal and the test signal at each fixed position one by one and performing cross-correlation calculations, the pressure field measurement and shape reconstruction of the human limbs can be realized.

[0036] 8) Group the pressure information distributed along the physical length of the optical fiber according to the optical fiber layout of test platform 14. The pressure information of the first half of the optical fiber (1 / 2n rows) does not need to be processed, while the pressure information of the second half (1 / 2n rows) needs to be transposed. Combine the first 1 / 2n rows of data with the transposed 1 / 2n rows of data into an n-row data matrix.

[0037] 9) Perform color mapping on the n-row data matrix processed in step 8) to obtain the final pressure distribution map of the human limbs;

[0038] 10) Different limbs have different pressure fields. Repeat step 5) to obtain the collected signal as a reference signal and repeat steps 6)-9) to obtain the pressure field distribution of different limbs.

[0039] This device has excellent electromagnetic interference resistance, high stability, repeatability, high spatial resolution, and simple structure. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of an embodiment;

[0041] Figure 2 The fiber optic cable layout of the test platform is shown in this embodiment.

[0042] Figure 3 This is a schematic diagram of the overall optical fiber of the test platform in the embodiment;

[0043] Figure 4 This is a diagram showing the measurement results of the foot pressure field in the embodiment;

[0044] Figure 5 The diagram shows the measurement results of the hand pressure field in the embodiment.

[0045] In the figure, 1. Tunable laser 2. First fiber coupler 3. Second fiber coupler 4. Third fiber coupler 5. Delay fiber 6. Single-mode fiber 7. Polarization controller 8. Fiber circulator 9. Fourth fiber coupler 10. Fifth fiber coupler 11. First photodetector 12. Second photodetector 13. High-speed oscilloscope 14. Test platform. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this is not intended to limit the present invention.

[0047] Example:

[0048] Reference Figure 1 A pressure field measuring device for human limbs includes a tunable laser 1, a coupler, a circulator, a polarization controller 8, a photodetector, and a high-speed oscilloscope 14 connected in sequence, wherein:

[0049] The entire system is divided into two parts: a tunable laser 1, a first fiber coupler 2, a second fiber coupler 3, a parallel delay fiber 5 and a single-mode fiber 6, a fourth fiber coupler 9, and a first photodetector 11 are connected in sequence to form an external sampling clock unit connected to a high-speed oscilloscope 13; a tunable laser 1, a first fiber coupler 2, a third fiber coupler 4, a parallel polarization controller 7 and a fiber optic circulator 8, a fifth fiber coupler 10, a second photodetector 12, and a test platform 14 are connected in sequence to form a sensing interferometer, and the output of the second photodetector 12 is connected to the high-speed oscilloscope 13.

[0050] The light output from the tunable laser 1 is split into two paths by the first fiber coupler 2. One path sequentially passes through the second fiber coupler 3 and enters the parallel delay fiber 5 and single-mode fiber 6 respectively. They are then combined through the fourth fiber coupler 9 and enter the first photodetector 11 to form an external sampling clock unit. The other path sequentially passes through the third fiber coupler 4 and enters the parallel polarization controller 7 and the a port of the fiber circulator 8 respectively. The light from the b port of the fiber circulator 8 enters the test platform 14. The Rayleigh scattered light from the test platform 14 enters the c port of the fiber circulator 8 through the b port and mixes with the light from the polarization controller 7 at the fifth fiber coupler 10 to enter the second photodetector 12 to form a sensing optical path unit. The electrical signals of the external sampling clock unit and the sensing optical path unit are acquired and analyzed by the high-speed oscilloscope 13.

[0051] The test platform 14 is composed of single-mode optical fibers laid out in a flat manner to form a ring-shaped body with a rectangular shape in the middle and symmetrical semi-circular arcs at both ends. The ring-shaped body is wound in multiple layers, with n layers. The side lengths of the rectangles are L and the diameters of the semi-circular arcs are R. The single-mode optical fibers on one side of all ring-shaped bodies are evenly laid out on the flexible plate, and the spacing between each adjacent optical fiber is R / n.

[0052] like Figure 3 As shown, the test plane fiber optic cable layout is as follows: Figure 2 As shown, starting from the initial segment, the optical fibers are laid out along the direction of the red arrow to form a paperclip shape. After N layers of stacking, a complete rounded rectangle is formed. In this example, the number of ring layers is 18. The optical fibers are laid out in n=36 rows, the spacing between adjacent optical fibers is 5mm, L is 260mm, and R is 90mm.

[0053] All of the above connections are made using FC / APC flanges.

[0054] The tunable laser 1 is model TSL-550, with a tuning range of 1520-1580nm and a tuning speed of 60nm / s.

[0055] The photodetector is model PDB430C, with an operating wavelength of 800~1700nm and a response bandwidth of 350MHz.

[0056] The high-speed oscilloscope 14 is model MSO-S 254A, with a bandwidth of 2.5GHz and a sampling rate of 20GSa / s.

[0057] The splitting ratio of the first fiber coupler 2 to the third fiber coupler 4 is 99%:1%. 1% of the light split from the first fiber coupler 2 enters the external clock through the second fiber coupler 3, and 99% of the light enters the sensing interferometer through the third fiber coupler 4. 1% of the light split from the third fiber coupler 4 enters the polarization controller 7, and 99% of the light split from the third fiber coupler 4 enters port a of the fiber optic circulator 8.

[0058] The splitting ratio of the second fiber coupler 3, the fourth fiber coupler 9, and the fifth fiber coupler 10 is 50%:50%.

[0059] The delay fiber 5 is 200m long and is model SM-28e.

[0060] In this example, the propagation path of the linearly swept laser is as follows: The linearly swept laser emitted by the tunable laser is split into two paths by the first fiber coupler. 1% of the light split from the first fiber coupler is split into two paths by the second fiber coupler. One path (50%) passes through a time-delay fiber, and the other path (50%) passes through a single-mode fiber. The two paths meet at the fourth fiber coupler and undergo beat frequency interference. The interference signal enters the first photodetector, which converts the interfering optical signal into an electrical signal. The photoelectric signal after interference is collected by a high-speed oscilloscope as external clock data. The remaining 99% of the light split from the first fiber coupler is split into two paths by the third fiber coupler. One 1% of the light split from the third fiber coupler passes through the polarization controller and reaches the fifth fiber coupler. Another 99% of the light split from the third fiber coupler passes through port a of the circulator and enters port b of the circulator, then enters the test plane. The backscattered Rayleigh light generated by the sensing fiber of the test plane passes through port b of the circulator and enters port c of the circulator, then enters the fifth fiber coupler. The light output from the polarization controller and the light output from port c of the circulator meet at the fifth fiber coupler and generate a beat frequency interference signal. The second photodetector converts the beat frequency interference optical signal into an electrical signal, which is collected by a high-speed oscilloscope as a sensing signal. The signal from the sensing interferometer is collected by the high-speed oscilloscope and used to reconstruct the distribution of the pressure field of the human limbs.

[0061] The working process of the pressure field measuring device for the human limbs in this example is as follows:

[0062] 1) The laser emitted by the tunable laser 1 enters the first fiber coupler 3 and is split into two beams. One beam enters the sensing optical path unit and the other enters the external clock unit. The beam entering the sensing optical path unit is split into two beams by the third fiber coupler 4. One beam entering the fiber optic circulator 8 is the intrinsic beam and the other beam entering the polarization controller 7 is the reference beam.

[0063] 2) In the sensing interferometer unit, the two beams split from the third fiber coupler 4 enter the polarization controller 7 and then the fifth fiber coupler 10. The other beam enters the test platform 14 from port a of the fiber circulator 8. The backscattered Rayleigh light in the test platform 14 enters the test platform 14 through port b of the fiber circulator 8 and is transmitted to port c. It converges with the light output from the polarization controller 7 at the fifth fiber coupler 10 and interferes. The second photodetector 12 converts the beat frequency interference light signal into an electrical signal and inputs it into the high-speed oscilloscope 13. According to the principle of optical heterodyne detection, the 1% signal light and 99% reference light split from the third fiber coupler can be expressed as:

[0064] ,

[0065] ,

[0066] in The initial frequency for TLS, This represents the random phase of the reference light. Indicates the delay position Reflectivity This indicates that the Rayleigh backscattered signal is in The random phase at time is coupled to the output signal of the second photodetector through the fifth fiber coupler. for:

[0067] ,

[0068] For two beams of light at time The phase difference;

[0069] 3) In the external clock unit, 1% of the light from the first fiber coupler 2 enters the second fiber coupler 3, and the second fiber coupler 3 splits the light into two 50%: 50% light paths: one path enters the delay fiber 5, and the other path enters the ordinary single-mode fiber 6. The two paths of light meet and interfere in the fourth coupler 9. The interference signal is converted into an electrical signal by the first photodetector 11 and input to the high-speed oscilloscope 13.

[0070] 4) In the external clock unit, a fixed beat frequency interference signal is generated and acquired by the high-speed oscilloscope 13. By performing a Fourier transform on the external clock interference signal, its frequency information is extracted and used as a reference to interpolate and resample the data of the sensing optical path unit to solve the nonlinear tuning effect of the laser emitted by the tunable light source. In this way, the acquired signal of the sensing interferometer unit is more accurate.

[0071] 5) In the sensing interferometer unit, keep the test platform 14 stationary and unloaded, and collect the backscattered Rayleigh spectral signal as a reference signal;

[0072] 6) In the sensing interferometer unit, when the human limbs are in flat contact with the test platform 14, the pressure will cause the backscattering Rayleigh signal on the optical fiber on the test platform 14 to change. The backscattering Rayleigh spectral signal is collected as a sensing signal.

[0073] 7) The cross-correlation algorithm was used to analyze the Rayleigh scattering spectrum drift of the reference signal and the sensor signal to obtain the pressure distribution information on the 14 optical fibers of the test platform. The beat frequency signal representing the two beams of light, which varies linearly with time, is the correlation function of the position of the scattering point on the test plane optical fiber, and is written as:

[0074] ,

[0075] Where x represents the position of the scattering point on the test plane fiber, n is the refractive index of the test plane fiber, and c is the speed of light in a vacuum. When the TLS performs a linear scan, scattering points at different positions on the test plane fiber correspond to different frequencies. The original OFDR signal is transformed to the frequency domain using a Fourier transform, and the position of the scattering point on the test plane fiber is derived based on the frequency of the spectrum, thus achieving fiber positioning. If the scan period is set to T, according to the properties of the Fourier transform, the frequency resolution of the system is... The theoretical spatial resolution can be expressed as:

[0076] ,

[0077] in This refers to the wavelength tuning range of the tunable laser. N data points at the same length are used as a sliding window W. When taking values ​​in the next sliding window, 80% of the data is repeated from the previous sliding window. In this case, the spatial resolution is 0.2 times the length of the sliding window. The length represented by the sliding window is:

[0078] ;

[0079] By matching the data windows of the reference signal and the test signal at each fixed position one by one and performing cross-correlation calculations, the pressure field measurement and shape reconstruction of the human limbs can be realized.

[0080] 8) Group the pressure information distributed along the physical length of the optical fiber according to the optical fiber layout of test platform 14. The pressure information of the first half of the optical fiber (rows 18) does not need to be processed, while the pressure information of the second half (rows 19-36) needs to be transposed. Combine the first 18 rows of data with the transposed rows 19-36 into a 36-row data matrix.

[0081] 9) Perform color mapping on the 36-row data matrix processed in step 8) to obtain the final pressure distribution map of the human limbs;

[0082] 10) Different limbs have different pressure fields. Repeat step 5) to obtain the collected signal as a reference signal and repeat steps 6)-9) to obtain the pressure field distribution of different limbs.

[0083] In this example, the measurement results of the pressure field of the hands and feet are shown in the figure below. Figure 5 , Figure 4 As shown.

Claims

1. A device for measuring the pressure field of human limbs, characterized in that, It includes a tunable laser, coupler, circulator, polarization controller, photodetector, and high-speed oscilloscope connected in sequence, wherein: The entire system is divided into two parts: an external sampling clock unit consisting of a tunable laser, a first fiber coupler, a second fiber coupler, a parallel delay fiber and a single-mode fiber, a fourth fiber coupler, and a first photodetector, connected in sequence, is connected to a high-speed oscilloscope; and a sensor interferometer consisting of a tunable laser, a first fiber coupler, a third fiber coupler, a parallel polarization controller and a fiber circulator, a fifth fiber coupler, a second photodetector, and a test platform, with the output of the second photodetector connected to the high-speed oscilloscope. The light output from the tunable laser is split into two paths by the first fiber coupler. One path sequentially passes through the second fiber coupler and enters the parallel delay fiber and single-mode fiber respectively. They are then combined through the fourth fiber coupler and enter the first photodetector to form an external sampling clock unit. The other path sequentially passes through the third fiber coupler and enters the parallel polarization controller and fiber circulator port a respectively. The light exiting from port b of the fiber circulator enters the test platform. The Rayleigh scattering light from the test platform passes through port b of the fiber circulator and enters port c. It then mixes with the light passing through the polarization controller at the fifth fiber coupler and enters the second photodetector to form a sensing optical path unit. The electrical signals from the external sampling clock unit and the sensing optical path unit are acquired and analyzed by a high-speed oscilloscope. The test platform is composed of single-mode optical fibers laid out in a flat manner to form a ring-shaped structure with a rectangular shape in the middle and symmetrical semi-circular arcs at both ends. The ring-shaped structure is wound in multiple layers, with n layers. The side lengths of the rectangles are L and the diameters of the semi-circular arcs are R. The single-mode optical fibers on one directional side of all the ring-shaped structures are evenly laid out on the flexible plate, and the spacing between each adjacent optical fiber is R / n. All of the above connections are made using FC / APC flanges.

2. The pressure field measuring device for human limbs according to claim 1, characterized in that, The tunable laser is model TSL-550, with a tuning range of 1520-1580nm and a tuning speed of 60nm / s.

3. The pressure field measuring device for human limbs according to claim 1, characterized in that, The photodetector is model PDB430C, with an operating wavelength of 800~1700nm and a response bandwidth of 350MHz.

4. The pressure field measuring device for human limbs according to claim 1, characterized in that, The high-speed oscilloscope is model MSO-S 254A, with a bandwidth of 2.5GHz and a sampling rate of 20GSa / s.

5. The pressure field measuring device for human limbs according to claim 1, characterized in that, The splitting ratio of the first fiber coupler to the third fiber coupler is 99%:1%. 1% of the light split from the first fiber coupler enters the external clock through the second fiber coupler, and 99% of the light enters the sensing interferometer through the third fiber coupler. 1% of the light split from the third fiber coupler enters the polarization controller, and 99% of the light split from the third fiber coupler enters the a port of the fiber circulator.

6. The pressure field measuring device for human limbs according to claim 1, characterized in that, The splitting ratio of the second, fourth, and fifth fiber couplers is 50%:50%.

7. The pressure field measuring device for human limbs according to claim 1, characterized in that, The delay fiber is 200m long and is model SM-28e.

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