OFDR Distributed Optical Fiber Measurement Device and Method for Three-Dimensional Printing of Drugs

Abstract

The present invention provides an OFDR distributed optical fiber measurement device and method for three-dimensional printing of drugs, including a tunable laser, an additional interference module, a main interference module, a temperature / distance real-time calibration module, a measurement optical fiber, a signal demodulation module, and a host computer. Beneficial effects of the present invention: By controlling the temperature of the temperature / distance real-time calibration module, a physical parameter reference value is provided for the measurement optical fiber. The measurement optical fiber is sequentially and evenly wound around the melting chamber of the three-dimensional printing drug production line and meets the minimum bending radius of the optical fiber, thereby realizing continuous and on-line measurement of multiple physical parameters of the three-dimensional printing drug production line.

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 3D 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 3D drug printing process, physical parameters such as the control point temperature and the control point position are crucial. The control accuracy of these physical parameters not only affects the normal operation of the 3D 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, many 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:

[0006] In a first aspect, the present invention provides an OFDR distributed optical fiber measurement device for three-dimensional printing of drugs, which includes a tunable laser, an additional interference module, a main interference module, a temperature / distance real-time calibration module, a measurement optical fiber, a signal demodulation module, and a host computer; the tunable laser is connected to the additional interference module and the main interference module through the measurement optical fiber respectively, the additional interference module is also communicatively connected to the signal demodulation module, the signal demodulation module is communicatively connected to the main interference module, the temperature / distance real-time calibration module, and the host computer respectively, and the measurement optical fiber is wound around both the temperature / distance real-time calibration module and the melting chamber;

[0007] The tunable laser is used to provide a high linear frequency modulation optical signal;

[0008] The additional interference module is a depolarization-free Michelson interferometer, which is used to generate an interference signal with equal optical frequency as the external clock signal of the acquisition device;

[0009] The main interference module is used to provide the interference between the distributed Rayleigh scattered light of the measurement optical fiber and the reference light;

[0010] 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;

[0011] The temperature / distance real-time calibration module is used to achieve precise control of the temperature of the measurement optical fiber, and meet the measurement of the standard length and initial temperature of the measurement optical fiber.

[0012] Further, the temperature / distance real-time calibration module includes a temperature controller, a mounting base plate, 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 plate, the measurement optical fiber is wound around the temperature equalizing block, and both the TEC and the thermocouple sensor are connected to the temperature controller.

[0013] Further, the temperature equalizing block is made of copper, and the surface of the temperature equalizing block is engraved with an optical fiber installation groove, and the measurement optical fiber is evenly wound around the optical fiber installation groove of the temperature equalizing block.

[0014] Further, the measurement optical fiber uses a polyimide-coated optical fiber, and the measurement optical fiber is evenly wound or pasted on the melting chamber and contacts the inner wall of the melting chamber.

[0015] Further, one measurement optical fiber is connected to multiple melting chambers.

[0016] Further, the multi-physical parameters of the three-dimensional printing of drugs by the OFDR distributed optical fiber measurement device include: temperature parameters of 50°C to 200°C and sensing point distance parameters of 0 m to 100 m.

[0017] Further, the sensing process of the OFDR distributed optical fiber measurement device includes:

[0018] 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:

[0019] 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;

[0020] A2. Perform FFT on the signal received by the signal demodulation module to convert it from the optical frequency domain to the distance domain;

[0021] 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;

[0022] 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.

[0023] 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:

[0024] 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;

[0025] 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;

[0026] 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;

[0027] 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;

[0028] S5. After this metering is completed, only the signal demodulation module and the upper computer of the OFDR distributed optical fiber measurement device are removed, and the measurement optical fiber is kept in the same position on the production line. During subsequent periodic metering, reconnect the signal demodulation module and the upper computer of the OFDR distributed optical fiber measurement device, and repeat steps S2 to S4.

[0029] Further, in steps S2 and S3, the temperature detection ranges of the reference physical parameter values along the optical fiber and the standard values of the physical parameters are both 50°C to 200°C, the temperature uncertainty U = 1°C (k = 2), where k is the confidence factor of the uncertainty, the spatial resolution ≤ 2 cm, and the sensing point distance is 0 m to 100 m.

[0030] Further, in step S1, the minimum bending radius is greater than 5 mm.

[0031] Compared with the prior art, the OFDR distributed optical fiber measurement device and method for three-dimensional printing of drugs according to the present invention have the following advantages:

[0032] The OFDR distributed optical fiber measurement device and method for three-dimensional printing of drugs according to the present invention. The OFDR distributed optical fiber 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 freedom in scenarios with limited space and portability, providing a new solution for on-line 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 reference value of the physical parameter is provided for the measurement optical fiber. The measurement optical fiber is sequentially and evenly wound around the melting chamber of the three-dimensional drug printing production line and meets the minimum bending radius of the optical fiber, so as to realize continuous and on-line measurement of multiple physical parameters of the three-dimensional drug printing production line. Description of the Drawings

[0033] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic 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 drawings:

[0034] Figure 1 It is a schematic diagram of the working principle of the OFDR distributed optical fiber measurement device according to the embodiment of the present invention;

[0035] Figure 2 It is a schematic diagram of the working principle of the temperature / distance real-time calibration module according to the embodiment of the present invention;

[0036] Figure 3 It is a schematic flowchart of the OFDR distributed optical fiber on-line measurement method according to the embodiment of the present invention.

[0037] Description of the reference numerals:

[0038] 1. Tunable laser; 2. Additional interference module; 3. Main interference module; 4. Temperature / distance real-time calibration module; 41. Thermostat; 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. Specific implementation manners

[0039] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0040] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is 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 thus cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0041] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "mount", "connect", "connection" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0042] The present invention will be described in detail below with reference to the drawings and in combination with embodiments.

[0043] Glossary:

[0044] OFDR: Optical Frequency Domain Reflectometry.

[0045] TEC: Thermoelectric Cooler.

[0046] Hilbert transform: In mathematics and signal processing, the Hilbert transform is a linear operator that generates a function with the same domain as the original function.

[0047] FFT: FFT is an efficient algorithm for DFT, known as the fast Fourier transform. The Fourier transform is one of the most fundamental methods in time-domain to frequency-domain transformation analysis. The discrete Fourier transform (DFT: Discrete Fourier Transform) applied in the field of digital processing is the basis for many digital signal processing methods.

[0048] As Figures 1 to 3 shown, the 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;

[0049] The tunable laser 1 provides a highly linear frequency-modulated optical signal for the optical frequency domain reflectometry system;

[0050] The additional interference module 2 is structured as a depolarization-free Michelson interferometer, which is used to generate interference signals with equal optical frequencies as the external clock signal of the acquisition device. This clock signal is used as the clock source of the analog-to-digital conversion device or is synchronously acquired to compensate for the influence of non-linear phase noise;

[0051] The main interference module 3 provides the interference between the distributed Rayleigh scattering of the measurement optical fiber 5 and the reference light;

[0052] 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;

[0053] The temperature / distance real-time calibration module 4 includes: a temperature controller 41, a mounting base plate 42, a temperature equalizing block 43, a TEC 44, and a thermocouple sensor 45, etc. The TEC 44 adjusts the direction and magnitude of the current through the temperature controller 41 to achieve the refrigeration or heating function. The temperature equalizing block 43 is made of copper, with an optical fiber mounting groove engraved on its surface. The measurement optical fiber 5 with a standard length is evenly wound around the mounting groove of the temperature equalizing block 43. It has good thermal conductivity and can quickly transfer the heat of the TEC 44 to the measurement 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.

[0054] The measurement optical fiber 5 mentioned above uses a polyimide-coated optical fiber, which has high temperature resistance. It is evenly wound or pasted on the melting chamber 8 (the melting chamber of the three-dimensional drug printing equipment production line), makes full contact with the wall of the melting chamber 8, and connects multiple melting chambers 8 through one measurement optical fiber 5 to achieve comprehensive, real-time continuous, and on-line physical parameter measurement of the entire three-dimensional drug printing production line.

[0055] 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.

[0056] The OFDR distributed fiber measurement method for 3D printed drugs includes the following steps:

[0057] 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.

[0058] 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;

[0059] 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;

[0060] After this metrology is completed, only the host of the OFDR distributed optical fiber measurement device (signal demodulation module 6 and upper computer 7) is removed, and the measurement optical fiber 5 is kept unchanged at the production line position. During subsequent periodic metrology, reconnect the OFDR measurement host and repeat the previous steps.

[0061] The temperature detection range of the reference physical parameter values along the optical fiber and the standard values of the physical parameters is 50°C to 200°C, the temperature uncertainty U = 1°C (k = 2), where k is the confidence factor of the uncertainty, the spatial resolution ≤ 2 cm, and the sensing point distance is (0 to 100) m.

[0062] The OFDR distributed optical fiber 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, and can provide extremely high degrees of freedom in scenarios with limited space and portability, providing a new solution for the online measurement and calibration of physical parameters in the three-dimensional drug printing production line.

[0063] Example 1

[0064] The OFDR distributed optical fiber measurement device for three-dimensional printed drugs, as Figure 1 shown, includes an upper 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 measurement optical fiber 5, etc. The continuous light output by the tunable laser 1 is divided into two paths by an optical fiber coupler. One path enters the additional interference module 2, and after passing through the optical fiber delay line of the Michelson interferometer, it returns to the main interference module 3 by the Faraday rotator mirror of the Michelson interferometer as a reference signal; the other path of light wave is injected into the measurement optical fiber 5. When this path of light wave propagates in the measurement optical fiber 5, it 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 measurement signals. The measurement signal and the reference light undergo beat frequency interference to obtain a beat frequency interference signal. The beat frequency interference signal undergoes data processing through the following demodulation process in the signal demodulation module 6:

[0065] 1) Use the OFDR system to collect the backward Rayleigh scattering spectrum information of the measurement optical fiber 5 before (reference signal) and after (measurement signal) the change of the physical parameter at the measurement point respectively, and transmit it to the signal demodulation module 6.

[0066] 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.

[0067] 3) After performing Hilbert on the distance domain signal, multiply it by a de-slanting filter using the de-slanting filtering method to obtain the denoised distance domain interference signal.

[0068] 4) Use the 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 cross-correlation peak. Then, based on the offset of the main cross-correlation peak, the position of the main cross-correlation peak, etc., calculate the change in the physical parameters at the point to be measured on the host computer 7.

[0069] Using the above system, only the change in the physical parameters of the measurement optical fiber 5 can be measured, and the absolute value of the physical parameters cannot be measured. 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:

[0070] 1) Before measurement, control the temperature / distance real-time calibration module 4 to stabilize the temperature control at 25°C. At this time, measure the Rayleigh scattered light in the measurement optical fiber 5 as the initial value of the physical parameters.

[0071] 2) After the measurement starts, start the production line. When the physical parameters of the production line change, measure the Rayleigh scattered light in the measurement optical fiber 5 again. By comparing the frequency shifts of the two Rayleigh scattered lights, obtain the standard value of the physical parameter change.

[0072] 3) Compare the standard value of the physical parameter change with the change value of the physical parameters of the production line. The difference is the result of the measurement calibration of the physical parameters of the production line.

[0073] The measurement optical fiber 5 proposed in the embodiment of the present disclosure uses a polyimide-coated optical fiber, which has high-temperature resistance. It is evenly wound or pasted on the melting chamber 8 (the melting chamber of the three-dimensional drug printing equipment production line), makes full contact with the wall of the melting chamber 8, and connects multiple melting chambers 8 through a single measurement optical fiber 5 to achieve comprehensive, real-time continuous, and on-line physical parameter measurement of the entire three-dimensional drug printing production line. The specific measurement process is as follows:

[0074] 1) Before the first measurement calibration, arrange the polyimide-coated measurement optical fiber 5 according to the layout of the melting chambers 8, wind or paste it on the walls of all the melting chambers 8 of the production line, and connect it to the OFDR distributed optical fiber measurement device through the APC / FC interface.

[0075] 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 TEC 44 to start heating and keep the temperature constant at 25°C. The heat of the TEC 44 is conducted to the measurement optical fiber 5 through the temperature equalizing block 43, thereby obtaining the reference physical parameter values along the optical fiber.

[0076] 3) Start the production line. The melting chambers 8 distributed at different positions on the production line are adjusted to the physical parameters required for printing drugs. By periodically obtaining the Rayleigh scattered light information, obtain the standard value of the physical parameter change.

[0077] 4) Compare the standard values of physical parameters with the display values of the physical parameter sensors built in the melting chamber 8 to achieve the measurement and calibration of the physical parameters of the three-dimensional drug printing production line.

[0078] 5) After this metrology is completed, remove the host of the OFDR device, keep the measurement optical fiber 5 in the production line position unchanged. During subsequent periodic metrology, directly connect to the host and repeat steps 2), 3), and 4).

[0079] Embodiment 2

[0080] Experimental data on the measurement of multiple physical parameters of a certain three-dimensional printed drug production line using the present invention.

[0081] 1) Temperature parameter measurement

[0082] Use the present invention 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 are calibrated simultaneously. Table 1 below only takes one of the thermocouple temperature sensors as an example for illustration.

[0083] Table 1

[0084] ;

[0085] As shown in the above table, measure the value of one thermocouple temperature sensor in the production line, obtain the standard temperature value through OFDR, and compare it with the thermocouple temperature value to calculate the indication error of this thermocouple temperature sensor. The maximum indication error is -0.84°C.

[0086] 2) Distance parameter measurement

[0087] Use the present invention to measure the distance of the heating points on the production line. In the range of (0 - 100), the measurement results are as follows. In this measurement, more than 50 heating point distances are calibrated simultaneously. Table 2 below only takes 7 of the heating points as an example for illustration.

[0088] Table 2

[0089] ;

[0090] As shown in the above table, measure the distances of 7 heating points on the production line, obtain the standard distance value through OFDR, and compare it with the position of the sensing point to calculate the distance indication error at each position. The maximum indication error is 0.1 m.

[0091] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within 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 change of the physical parameter at the test point on the host computer through the offset and position of the main peak of the cross-correlation on the host computer; The OFDR distributed fiber measurement method for 3D printed drugs includes 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. During 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; 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 to 200°C, the temperature uncertainty U=1°C (k=2), where k is the confidence factor of the uncertainty, the spatial resolution ≤2cm, and the sensing point distance is 0m to 100m.

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 of the OFDR distributed fiber optic measurement device include: temperature parameters of 50℃ to 200℃ and sensing point distance parameters of 0m to 100m.

5. The OFDR distributed optical fiber measurement device for three-dimensional printing of drugs according to claim 1, characterized in that: In step S1, the minimum bending radius is greater than 5 mm.

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