OFDR distributed optical fiber measuring device and method for three-dimensional printing medicine

Abstract

The invention provides an OFDR distributed optical fiber measuring device and method for three-dimensional printing medicine. The device comprises a tunable laser, an additional interference module, a main interference module, a temperature / distance real-time calibration module, a measuring optical fiber, a signal demodulation module and an upper computer. The device has the beneficial effects that by controlling the temperature of the temperature / distance real-time calibration module, a physical parameter reference value is provided for the measuring optical fibers, the measuring optical fibers are sequentially and uniformly wound on the melting chamber of the three-dimensional printing medicine production line, and the minimum bending radius of the optical fibers is met; therefore, continuous and online measurement of multiple physical parameters of the three-dimensional printing medicine production line is realized.

Description

Technical Field

[0001] The present invention belongs to the field of optical fiber transmission characteristic measurement, and in particular relates to an OFDR distributed optical fiber measurement device and method for three-dimensional printing of drugs. Background Art

[0002] The basic principle of the OFDR distributed optical fiber measurement device is to use the optical characteristics of optical fiber backscattering that changes with physical parameters. By comparing the transmission characteristic spectrum changes of the reference signal and the measurement signal, distributed and continuous measurement of physical parameters along the entire optical fiber can be achieved.

[0003] In addition, most new drug release systems rely on the fine design of the microstructure, composition, three-dimensional spatial distribution of drugs, and drug concentration distribution of the drug to achieve specific drug release behaviors. These properties are difficult to achieve with traditional pharmaceutical technology. The three-dimensional printing drug technology based on the fused deposition rapid prototyping process is a technology that heats and melts various wires and then stacks them into shape. This technology can easily control the local material composition, material concentration distribution, internal structure and surface characteristics of the product, and integrate many traditional processing processes on one machine, thereby achieving "layer-by-layer printing and layer-by-layer stacking". Its basic molding principle is: the solid resin material wire is fed into the printing nozzle through the gear propulsion transmission device and heated at the nozzle. According to the different properties of the material, the heating temperature range is (50~200)℃. After the wire is melted into a liquid state, it is extruded through the print head. The extruded wire-like material will be accumulated on the printing platform according to the path set by the model. In the three-dimensional drug printing process, the state of physical parameters such as the control point temperature and the control point position is crucial. The control accuracy of these physical parameters not only affects the normal operation of the three-dimensional printing equipment, but also affects the effectiveness of the drug. Traditional physical parameter measurement generally uses thermocouple in-situ measurement method, which can only perform point detection on the production line and is difficult to achieve position, global, and online temperature measurement. It is also prone to corrosion and degradation, resulting in inaccurate measurement data. In addition, the numerous sensors distributed on the production line need to be regularly inspected and calibrated. Due to the large number and the need to stop production during measurement, this also brings inconvenience to production work. Therefore, the problem of online measurement and calibration of physical parameters of 3D drug printing production lines needs to be solved urgently. Summary of the invention

[0004] In view of this, the present invention aims to propose an OFDR distributed fiber optic measurement device and method for three-dimensional printing of drugs to solve at least one problem existing in the above-mentioned prior art.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows: In a first aspect, the present invention provides an OFDR distributed optical fiber measurement device for three-dimensional printing of drugs, comprising a tunable laser, an additional interference module, a main interference module, a temperature / distance real-time calibration module, a measuring optical fiber, a signal demodulation module and a host computer; the tunable laser is respectively connected to the additional interference module and the main interference module through the measuring optical fiber, the additional interference module is also communicatively connected to the signal demodulation module, the signal demodulation module is respectively communicatively connected to the main interference module, the temperature / distance real-time calibration module and the host computer, and the temperature / distance real-time calibration module and the melting chamber are both wound with measuring optical fibers; The tunable laser is used to provide a high linear frequency modulated optical signal; The additional interference module is a depolarized Michelson interferometer, which is used to generate an interference signal of equal optical frequency as an external clock signal of the acquisition device; The main interference module is used to provide interference between the distributed Rayleigh scattered light of the measuring fiber and the reference light; The signal demodulation module uses the signal generated by the additional interference module as its external clock, digitizes the electrical signal output by the main interference module, and demodulates and analyzes it; The temperature / distance real-time calibration module is used to achieve accurate control of the temperature of the measuring optical fiber, and meet the measurement of the standard length and initial temperature of the measuring optical fiber.

[0006] Furthermore, the temperature / distance real-time calibration module includes a temperature controller, a mounting base, a temperature equalizing block, a TEC and a thermocouple sensor. The thermocouple sensor, the TEC and the temperature equalizing block are respectively mounted on the mounting base, a measuring optical fiber is wound around the temperature equalizing block, and the TEC and the thermocouple sensor are both connected to the temperature controller.

[0007] Furthermore, the temperature-averaging block is made of copper, and a fiber installation groove is engraved on the surface of the temperature-averaging block, and the measuring optical fiber is evenly wound on the fiber installation groove of the temperature-averaging block.

[0008] Furthermore, the measuring optical fiber is a polyimide coated optical fiber, and the measuring optical fiber is evenly wound or pasted on the melting chamber and contacts the inner wall of the melting chamber.

[0009] Furthermore, one measuring optical fiber is connected to a plurality of melting chambers.

[0010] Furthermore, the multi-physical parameters of 3D printed drugs measured by the OFDR distributed fiber optic measurement device include: temperature parameters of 50°C to 200°C and sensing point distance parameters of 0m to 100m.

[0011] Furthermore, the sensing process of the OFDR distributed optical fiber measurement device includes: The continuously tuned light output by the tunable laser is divided into two paths by the fiber coupler. One path enters the additional interference module, passes through the fiber delay line, and then returns to the main interference module by the Faraday rotator. The other path of light waves is injected into the measurement fiber. When this path of light waves propagates in the measurement fiber, it will continuously generate backscattered Rayleigh light. After being affected by the changes in the multiple physical parameters of the 3D printed drug, the backscattered Rayleigh light also enters the main interference module and generates beat frequency interference with the reference light. The beat frequency interference signal is processed in the signal demodulation module through the following demodulation process: A1. Using OFDR to collect the backscattering spectrum information of the measuring optical fiber before and after the physical parameters of the measured point change, and transmit it to the signal demodulation module; A2. Perform FFT on the signal received by the signal demodulation module to convert it from the optical frequency domain to the distance domain; A3, after performing Hilbert transform on the range domain signal, multiply the de-skewing filter by the de-skewing filter to obtain the denoised range domain interference signal; A4. Use IFFT to convert the distance domain interference signal back to the optical frequency domain, perform cross-correlation on the reference signal and the measurement signal in the optical frequency domain to obtain the main peak of the cross-correlation, and then calculate the physical parameter changes at the test point on the host computer through the offset and position of the main peak of the cross-correlation.

[0012] In a second aspect, based on the same concept, the present invention also provides an OFDR distributed optical fiber measurement method for three-dimensional printing of drugs, comprising the following steps: S1. During the first measurement, according to the measurement requirements of the multi-physical parameters of 3D printed drugs, the measuring optical fiber is evenly wound or pasted on the melting chamber in sequence, and the minimum bending radius of the measuring optical fiber is met; S2. After the OFDR distributed optical fiber measurement device is powered on, the temperature of the temperature / distance real-time calibration module is kept constant at 25°C to obtain the reference physical parameter values ​​along the optical fiber; S3, starting the production line, adjusting the melting chambers at different positions of the production line to the physical parameters required for printing the drug, and obtaining the standard values ​​of the physical parameters by periodically acquiring Rayleigh scattered light information; S4, comparing the standard value of the physical parameter with the display value of the physical parameter sensor provided in the melting chamber to achieve physical parameter measurement calibration of the three-dimensional drug printing production line; S5. After the current measurement is completed, only the signal demodulation module and the host computer of the OFDR distributed optical fiber measurement device are removed, and the measurement optical fiber is kept unchanged in the production line position. In the subsequent periodic measurement, the signal demodulation module and the host computer of the OFDR distributed optical fiber measurement device are reconnected, and steps S2 to S4 are repeated.

[0013] Furthermore, in step S2 and step S3, the temperature detection range of the benchmark physical parameter values ​​and the standard values ​​of the physical parameters along the optical fiber is 50°C~200°C, the temperature uncertainty is U=1°C (k=2), where k is the confidence factor of the uncertainty, the spatial resolution is ≤2cm, and the sensing point distance is 0m~100m.

[0014] Furthermore, in step S1, the minimum bending radius is greater than 5 mm.

[0015] Compared with the prior art, the OFDR distributed optical fiber measurement device and method for three-dimensional printing of drugs described in the present invention have the following advantages: The OFDR distributed fiber optic measurement device and method for three-dimensional printing of drugs described in the present invention, the OFDR distributed fiber optic measurement device of the present application has the advantages of high precision, high real-time performance, long distance, high temperature resistance, corrosion resistance, continuous measurement and strong anti-electromagnetic interference ability, and can provide extremely high degrees of freedom in scenarios with limited space and portability, and provides a new solution for the online measurement and calibration of physical parameters of the three-dimensional drug printing production line. By controlling the temperature of the temperature / distance real-time calibration module, a physical parameter reference value is provided for the measuring optical fiber. The measuring optical fiber is uniformly wound on the melting chamber of the three-dimensional printing drug production line in turn and meets the minimum bending radius of the optical fiber, thereby realizing continuous and online measurement of multiple physical parameters of the three-dimensional printing drug production line. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 A schematic diagram of the working principle of the OFDR distributed optical fiber measurement device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the working principle of the temperature / distance real-time calibration module according to an embodiment of the present invention; Figure 3 The figure is a flow chart of the OFDR distributed optical fiber online measurement method according to an embodiment of the present invention.

[0017] Description of reference numerals: 1. Tunable laser; 2. Additional interference module; 3. Main interference module; 4. Temperature / distance real-time calibration module; 41. Temperature controller; 42. Mounting base plate; 43. Temperature equalizing block; 44. TEC; 45. Thermocouple sensor; 5. Measuring optical fiber; 6. Signal demodulation module; 7. Host computer; 8. Melting chamber. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0019] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0021] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0022] Glossary: OFDR: Optical Frequency Domain Reflectometry.

[0023] TEC: semiconductor cooling chip.

[0024] Hilbert transform: In mathematics and signal processing, the Hilbert transform is a linear operator that produces a function with the same domain as the function. FFT: FFT is an efficient algorithm of DFT, called fast Fourier transform. Fourier transform is one of the most basic methods in time domain-frequency domain transform analysis. Discrete Fourier transform (DFT: Discrete Fourier Transform) used in the field of digital processing is the basis of many digital signal processing methods.

[0025] like Figures 1 to 3As shown, an OFDR distributed optical fiber measurement device for three-dimensional printing of drugs includes a host computer 7, a tunable laser 1, an additional interference module 2, a main interference module 3, a signal demodulation module 6, a temperature / distance real-time calibration module 4 and a measurement optical fiber 5; The tunable laser 1 provides a high linear frequency modulated optical signal for the optical frequency domain reflection system; The structure of the additional interference module 2 is a depolarized Michelson interferometer, which is used to generate an interference signal of equal optical frequency as an external clock signal of the acquisition device, and the clock signal is used as a clock source of the analog-to-digital conversion device or is synchronously acquired to compensate for the influence of nonlinear phase noise; The main interference module 3 provides interference between the distributed Rayleigh scattering of the measurement optical fiber 5 and the reference light; The signal demodulation module 6 uses the signal generated by the additional interference module 2 as its external clock, digitizes the electrical signal output by the main interference module 3, and demodulates and analyzes it according to the algorithm; The temperature / distance real-time calibration module 4 includes: a temperature controller 41, a mounting base plate 42, a temperature equalizing block 43, TEC44 and a thermocouple sensor 45, etc. TEC44 adjusts the direction and size of the current through the temperature controller 41 to achieve cooling or heating functions. The temperature equalizing block 43 is made of copper and has an optical fiber mounting groove engraved on the surface. The standard length of the measuring optical fiber 5 is evenly wound on the mounting groove of the temperature equalizing block 43, and has good thermal conductivity. It can quickly transfer the heat of the TEC44 to the measuring optical fiber 5. The temperature control accuracy is ±0.05°C, which can achieve precise control of the optical fiber temperature and meet the measurement of the standard length and initial temperature of the optical fiber.

[0026] The measuring optical fiber 5 is made of polyimide coated optical fiber, which has high temperature resistance. It is evenly wound or pasted on the melting chamber 8 (melting chamber of the three-dimensional drug printing equipment production line), fully in contact with the wall of the melting chamber 8, and multiple melting chambers 8 are connected through one measuring optical fiber 5 to achieve comprehensive, real-time continuous, and online physical parameter measurement of the entire three-dimensional drug printing production line.

[0027] In a preferred embodiment of the present invention, the tunable laser 1 is configured to generate a stable, high-quality optical signal and transmit it through an optical fiber; the measuring optical fiber 5, as a physical parameter sensitive medium, is configured to generate a backscattered optical signal for the incident light, and when the physical parameter changes, the optical signal of the measuring optical fiber 5 changes; the measuring optical fiber 5 adopts a polyimide coated optical fiber, which can meet the measurement environment of 50°C to 200°C and has a certain corrosion resistance. The length of the measuring optical fiber 5 determines the temperature measurement range, and the length of the measuring optical fiber 5 is generally 50 m. ~100m, customized according to actual needs, can also be expanded into multi-channel measurement optical fiber 5 through optical switches to expand the measurement space range of physical parameters; additional interference module 2 is used to generate reference light and compensate for the influence of nonlinear phase noise; main interference module 3 is used to detect beat frequency signal and generate interference signal; signal demodulation module 6 is configured to convert optical signal into current or voltage signal. Since the scattered signal is very weak, the photodetector must have the characteristics of high sensitivity, fast response and low noise to ensure that these optical signals can be accurately detected; and it can complete the processing of beat frequency interference signal, use the cross-correlation algorithm to demodulate the change of the corresponding wavelength, and finally output the measurement result of physical parameters. Temperature / distance real-time calibration module 4: It is configured to place the starting section of the standard length measurement optical fiber 5 in the temperature / distance real-time calibration module 4, and the temperature / distance real-time calibration module 4 sets the stable temperature to 25℃ to provide the initial physical parameter value for the OFDR online calibration device; the temperature / distance real-time calibration module 4 can receive the control signal of the signal demodulation module 6 to change the temperature.

[0028] The OFDR distributed fiber measurement method for 3D printed drugs includes the following steps: During the first measurement, the measuring optical fiber 5 is uniformly wound or pasted on the melting chamber 8 in sequence according to the physical parameter measurement requirements of the production line, and the minimum bending radius of the optical fiber is met. In this embodiment, bending will cause a strong light reflection peak, affecting data collection and processing. According to experimental tests, the minimum bending radius should be greater than 5 mm, which can effectively reduce the influence of the reflected light signal. Connect the measuring optical fiber 5 to the OFDR distributed optical fiber measuring device, and after powering on, keep the temperature of the temperature / distance real-time calibration module 4 constant at 25°C to obtain the benchmark physical parameter values ​​along the optical fiber; The production line is started, and the melting chambers 8 distributed at different positions of the production line are adjusted to the physical parameters required for printing drugs. By periodically acquiring Rayleigh scattered light information, the standard values ​​of the physical parameters are obtained, and compared with the display values ​​of the physical parameter sensors provided by the production line, so as to realize the physical parameter measurement and calibration of the three-dimensional drug printing production line; After the measurement is completed, only the OFDR distributed optical fiber measurement device host (signal demodulation module 6 and host computer 7) is removed, and the measurement optical fiber 5 remains unchanged in the production line. When performing subsequent periodic measurement, reconnect the OFDR measurement host and repeat the previous steps.

[0029] The temperature detection range of the benchmark physical parameter values ​​and standard values ​​of the physical parameters along the optical fiber is 50℃~200℃, the temperature uncertainty is U=1℃(k=2), where k is the confidence factor of the uncertainty, the spatial resolution is ≤2cm, and the sensing point distance is (0~100)m.

[0030] OFDR distributed fiber optic sensing technology has the advantages of high precision, high real-time performance, long distance, high temperature resistance, corrosion resistance, continuous measurement and strong anti-electromagnetic interference ability. It can provide extremely high degrees of freedom in scenarios with limited space and portability, and provides a new solution for the online measurement and calibration of physical parameters of 3D drug printing production lines.

[0031] Example 1 OFDR distributed fiber optic measurement device for 3D printing of drugs, such as Figure 1 As shown, it includes a host computer 7, a tunable laser 1, an additional interference module 2, a main interference module 3, a signal demodulation module 6, a temperature / distance real-time calibration module 4, a measuring optical fiber 5, etc. The continuous light output by the tunable laser 1 is divided into two paths by the optical fiber coupler. One path enters the additional interference module 2, passes through the optical fiber delay line of the Michelson interferometer, and is returned to the main interference module 3 by the Faraday rotation mirror of the Michelson interferometer as a reference signal; the other path of light waves is injected into the measuring optical fiber 5. When the light waves propagate in the measuring optical fiber 5, they will continuously generate backward Rayleigh scattered light. After these scattered lights are affected by the changes in the physical parameters of the production line, they also enter the main interference module 3 as the measuring signal. The measuring signal and the reference light undergo beat frequency interference to obtain a beat frequency interference signal. The beat frequency interference signal is processed in the signal demodulation module 6 through the following demodulation process: 1) The OFDR system is used to collect the backscattering spectrum information of the measuring optical fiber 5 before the physical parameters of the measured point change (reference signal) and after the physical parameters change (measurement signal), and transmit it to the signal demodulation module 6.

[0032] 2) Perform FFT on the signal received by the signal demodulation module 6 to convert it from the optical frequency domain to the distance domain.

[0033] 3) After Hilbert filtering the range domain signal, multiply it by the de-skewing filter to obtain the denoised range domain interference signal.

[0034] 4) Use IFFT to convert the distance domain interference signal back to the optical frequency domain, perform cross-correlation on the reference signal and the measurement signal in the optical frequency domain to obtain the main peak of the cross-correlation, and then calculate the physical parameter changes at the test point on the host computer 7 through the offset of the main peak of the cross-correlation, the position of the main peak of the cross-correlation, etc.

[0035] The above system can only measure the change in the physical parameters of the optical fiber 5, but cannot measure the absolute value of the physical parameters. Therefore, when measuring the physical parameters of the production line, it is necessary to measure the Rayleigh scattered light in the optical fiber 5 twice: 1) Before measurement, control the temperature / distance real-time calibration module 4 to stabilize the temperature at 25°C. At this time, measure the Rayleigh scattered light in the measurement optical fiber 5 as the initial value of the physical parameter.

[0036] 2) After the measurement begins, the production line is started. When the physical parameters of the production line change, the Rayleigh scattered light in the measuring optical fiber 5 is measured again. By comparing the frequency shifts of the two Rayleigh scattered lights, the standard value of the physical parameter change is obtained.

[0037] 3) Compare the standard value of the physical parameter change with the physical parameter change value of the production line. The difference is the result of the physical parameter measurement and calibration of the production line.

[0038] The measuring optical fiber 5 proposed in the embodiment of the present disclosure adopts a polyimide coated optical fiber with high temperature resistance. It is evenly wound or pasted on the melting chamber 8 (melting chamber of the three-dimensional drug printing equipment production line), fully in contact with the wall of the melting chamber 8, and multiple melting chambers 8 are connected through one measuring optical fiber 5 to achieve comprehensive, real-time continuous, and online physical parameter measurement of the entire three-dimensional drug printing production line. The specific measurement process is: 1) Before the first measurement and calibration, the polyimide coated measuring optical fiber 5 is arranged according to the melting chamber 8, wound or pasted on the wall of all melting chambers 8 of the production line, and connected to the OFDR distributed optical fiber measuring device through the APC / FC interface.

[0039] 2) After the OFDR distributed optical fiber measurement device is powered on, the temperature controller 41 of the temperature / distance real-time calibration module 4 controls the TEC44 to start heating and keep the temperature constant at 25°C. The temperature of TEC44 transfers the heat to the measuring optical fiber 5 through the temperature equalizing block 43, thereby obtaining the benchmark physical parameter values ​​along the optical fiber.

[0040] 3) The production line is started, and the melting chambers 8 distributed at different positions of the production line are adjusted to the physical parameters required for printing the drug. By periodically acquiring Rayleigh scattered light information, the standard value of the physical parameter change is obtained.

[0041] 4) Compare the standard value of the physical parameter with the displayed value of the physical parameter sensor provided in the melting chamber 8 to achieve physical parameter measurement calibration of the three-dimensional drug printing production line.

[0042] 5) After the measurement is completed, remove the OFDR device host and keep the measuring fiber 5 in the production line. For subsequent periodic measurement, directly connect to the host and repeat steps 2) 3) 4).

[0043] Example 2 The present invention is used to measure experimental data of multiple physical parameters of a three-dimensional printing drug production line.

[0044] 1) Temperature parameter measurement The present invention is used to measure the thermocouple temperature sensor (i.e., thermocouple sensor 45) used on the production line. In the temperature range of 80°C to 120°C, the measurement results are as follows. In this measurement, more than 50 thermocouple temperature sensors 45 are calibrated at the same time. Table 1 below only takes one of the thermocouple temperature sensors as an example.

[0045] Table 1 ; As shown in the table above, the value of a thermocouple temperature sensor in the production line was measured, the standard temperature value was obtained through OFDR, and compared with the thermocouple temperature value, and the indication error of the thermocouple temperature sensor was calculated. The maximum indication error was -0.84℃.

[0046] 2) Distance parameter measurement The present invention is used to measure the distance of heating points on the production line. Within the range (0~100), the measurement results are as follows. The number of heating point distances calibrated simultaneously in this measurement is greater than 50. Table 2 below only takes 7 of the heating points as an example.

[0047] Table 2 ; As shown in the table above, the distances of the seven heating points on the production line were measured, and the standard distance values ​​were obtained through OFDR. They were compared with the sensing point positions, and the distance indication error of each position was calculated. The maximum indication error was 0.1m.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. OFDR distributed fiber optic measurement device for 3D printing of drugs, characterized by: It includes a tunable laser, an additional interference module, a main interference module, a temperature / distance real-time calibration module, a measuring optical fiber, a signal demodulation module and a host computer; the tunable laser is respectively connected to the additional interference module and the main interference module through the measuring optical fiber, the additional interference module is also connected to the signal demodulation module for communication, the signal demodulation module is respectively connected to the main interference module, the temperature / distance real-time calibration module and the host computer for communication, and the temperature / distance real-time calibration module and the melting chamber are both wound with measuring optical fibers; The tunable laser is used to provide a high linear frequency modulated optical signal; The additional interference module is a depolarized Michelson interferometer, which is used to generate an interference signal of equal optical frequency as an external clock signal of the acquisition device; The main interference module is used to provide interference between the distributed Rayleigh scattered light of the measuring fiber and the reference light; The signal demodulation module uses the signal generated by the additional interference module as its external clock, digitizes the electrical signal output by the main interference module, and demodulates and analyzes it; The temperature / distance real-time calibration module is used to achieve accurate control of the temperature of the measuring optical fiber, so as to meet the measurement of the standard length and initial temperature of the measuring optical fiber; The measuring optical fiber is a polyimide coated optical fiber, which is evenly wound or pasted on the melting chamber and contacts the inner wall of the melting chamber; One measuring optical fiber is connected to a plurality of melting chambers; The sensing process of the OFDR distributed optical fiber measurement device includes: The continuously tuned light output by the tunable laser is divided into two paths by the fiber coupler. One path enters the additional interference module, passes through the fiber delay line of the Michelson interferometer, and then returns to the main interference module by the Faraday rotator of the Michelson interferometer as a reference signal. The other path of light waves is injected into the measuring fiber. This path of light waves can continuously generate backscattered Rayleigh light when propagating in the measuring fiber. The backscattered Rayleigh light is affected by the changes in the multiple physical parameters of the 3D printed drug and also enters the main interference module as a measurement signal. The measurement signal and the reference signal undergo beat frequency interference to obtain a beat frequency interference signal. The beat frequency interference signal is processed in the signal demodulation module through the following demodulation process: A1. Using OFDR to collect the backscattering spectrum information of the measuring optical fiber before and after the physical parameters of the measured point change, and transmit it to the signal demodulation module; A2. Perform FFT on the signal received by the signal demodulation module to convert it from the optical frequency domain to the distance domain; A3, after performing Hilbert transform on the range domain signal, multiply the de-skewing filter by the de-skewing filter to obtain the denoised range domain interference signal; A4. Use IFFT to convert the distance domain interference signal back to the optical frequency domain, perform cross-correlation on the reference signal and the measurement signal in the optical frequency domain to obtain the main peak of the cross-correlation, and then calculate the physical parameter changes at the test point on the host computer through the offset and position of the main peak of the cross-correlation.

2. The OFDR distributed optical fiber measurement device for three-dimensional printing of drugs according to claim 1, characterized in that: The temperature / distance real-time calibration module includes a temperature controller, a mounting base, a temperature equalizing block, a TEC and a thermocouple sensor. The thermocouple sensor, the TEC and the temperature equalizing block are respectively mounted on the mounting base, a measuring optical fiber is wound on the temperature equalizing block, and the TEC and the thermocouple sensor are both connected to the temperature controller.

3. The OFDR distributed optical fiber measurement device for three-dimensional printing of drugs according to claim 2, characterized in that: The temperature-averaging block is made of copper, and an optical fiber installation groove is engraved on the surface of the temperature-averaging block. The measuring optical fiber is evenly wound on the optical fiber installation groove of the temperature-averaging block.

4. The OFDR distributed optical fiber measurement device for three-dimensional printing of drugs according to claim 1, characterized in that: The multi-physical parameters of 3D printed drugs measured by the OFDR distributed fiber optic measurement device include: temperature parameters of 50℃~200℃ and sensing point distance parameters of 0m~100m.

5. An OFDR distributed optical fiber measurement method for three-dimensional printing of drugs, applied to an OFDR distributed optical fiber measurement device for three-dimensional printing of drugs as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: S1. During the first measurement, according to the measurement requirements of the multi-physical parameters of 3D printed drugs, the measuring optical fiber is evenly wound or pasted on the melting chamber in sequence, and the minimum bending radius of the measuring optical fiber is met; S2. After the OFDR distributed optical fiber measurement device is powered on, the temperature of the temperature / distance real-time calibration module is kept constant at 25°C to obtain the reference physical parameter values ​​along the optical fiber; S3, starting the production line, adjusting the melting chambers at different positions of the production line to the physical parameters required for printing the drug, and obtaining the standard values ​​of the physical parameters by periodically acquiring Rayleigh scattered light information; S4, comparing the standard value of the physical parameter with the display value of the physical parameter sensor provided in the melting chamber to achieve physical parameter measurement calibration of the three-dimensional drug printing production line; S5. After the current measurement is completed, only the signal demodulation module and the host computer of the OFDR distributed optical fiber measurement device are removed, and the measurement optical fiber is kept unchanged in the production line position. In the subsequent periodic measurement, the signal demodulation module and the host computer of the OFDR distributed optical fiber measurement device are reconnected, and steps S2 to S4 are repeated.

6. The OFDR distributed optical fiber measurement method for three-dimensional printing of drugs according to claim 5, characterized in that: In step S2 and step S3, the temperature detection range of the reference physical parameter values ​​and the standard values ​​of the physical parameters along the optical fiber is 50°C~200°C, the temperature uncertainty is U=1°C (k=2), where k is the confidence factor of the uncertainty, the spatial resolution is ≤2cm, and the sensing point distance is 0m~100m.

7. The OFDR distributed optical fiber measurement method for three-dimensional printing of drugs according to claim 5, characterized in that: In step S1, the minimum bending radius is greater than 5 mm.

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