Pen-type optical fiber spectrum interference spacing measuring probe and measuring system

Abstract

The invention belongs to the field of distance measurement, and particularly discloses a pen type optical fiber spectrum interference distance measuring probe and a measuring system. The probe comprises an adjusting unit and a measuring unit, the adjusting unit comprises a bottom shell, a measuring shell, a limiting shell and an elastic piece, the bottom shell is connected with the limiting shell, the measuring shell is arranged between the bottom shell and the limiting shell in an axially movable mode, the bottom shell and the measuring shell are each provided with a distance positioning part, and the elastic piece is used for providing elastic force enabling the measuring shell to be separated from the bottom shell; the measuring unit comprises an optical fiber spectrum interference module and a reflection module, one of the optical fiber spectrum interference module and the reflection module is arranged in the measuring shell, the other of the optical fiber spectrum interference module and the reflection module is arranged in the bottom shell, and the optical fiber spectrum interference module and the reflection module form a Michelson interferometer; the probe has the advantages of being high in measurement precision and reliability, small in size, large in measurement range and easy and convenient to operate, is suitable for precise measurement of various gaps, and is particularly suitable for precise interval measurement of the gaps in a narrow space.

Description

Technical Field

[0001] The present application belongs to the field of distance measurement, and more specifically, relates to a pencil-type optical fiber spectral interferometry distance measurement probe and a measurement system. Background Art

[0002] Spacing measurement is a key link in industrial manufacturing and mechanical processing. It plays an irreplaceable role in ensuring the precise fit of mechanical parts and the safe and stable operation of equipment. For example, if the parallelism of the flange spacing does not meet the requirements, it may cause the flange seal to fail, and in severe cases, it may cause the unit to shut down.

[0003] However, current traditional spacing measurement equipment often has the problem of large probe size, which makes it difficult to insert into the gap; at the same time, traditional spacing measurement methods, such as vernier caliper method and feeler gauge measurement method, have the problem of low measurement accuracy and inability to measure in narrow spaces.

[0004] Related technologies, such as patent application CN119667698A, titled "A Gap Measurement Device Based on Laser Ranging," propose extending the laser ranging portion into the gap and performing data processing outside the gap. However, this laser ranging portion requires contact with the inner surface of the object to be measured via a magnet, which complicates operation. Furthermore, the reflectivity of the inner surface affects the gap measurement, resulting in low reliability and urgent need for improvement. Summary of the Invention

[0005] In response to the defects or improvement needs of the existing technology, the present application provides a pencil-type fiber optic spectral interferometry distance measurement probe and measurement system, which aims to achieve high-precision and high-reliability distance measurement in narrow environments.

[0006] The present application provides a pencil-type optical fiber spectral interferometry distance measurement probe, specifically comprising: The adjusting unit is pen-shaped and includes a bottom shell, a measuring shell, a limiting shell, and an elastic member. The bottom shell is connected to the limiting shell, the measuring shell is axially movably disposed between the bottom shell and the limiting shell, and the elastic member is used to provide an elastic force to separate the measuring shell from the bottom shell. A measuring unit, comprising a fiber optic spectrum interference module and a reflection module, wherein one of the fiber optic spectrum interference module and the reflection module is disposed in the measuring housing, and the other is disposed in the bottom housing, and the fiber optic spectrum interference module and the reflection module constitute a Michelson interferometer; Among them, the bottom shell and the measuring shell are both provided with spacing positioning parts. Under the action of the elastic force, the two spacing positioning parts are configured to adaptively abut against the two opposite walls of the gap to be measured when they are released after being compressed and closed, and at the same time drive the fiber optic spectral interference module and the reflection module away from each other to change the optical path difference of the Michelson interferometer.

[0007] As a further preferred embodiment, the bottom shell is provided with a threaded hole extending through the bottom shell in the axial direction, the reflection module is threadedly connected in the threaded hole, and the reflection module has a reflection surface facing the fiber optic spectrum interference module.

[0008] As a further preferred embodiment, the fiber spectral interferometer module includes an optical fiber, a collimator and a cubic beam splitter, wherein: The optical fiber is used to transmit the optical signal to the collimator for collimation, and then the collimated optical signal reaches the cubic beam splitter and is split into reflected light and transmitted light; the transmitted light can be reflected back to the cubic beam splitter through the reflection module to form interference with the reflected light.

[0009] As a further preferred embodiment, the adjustment unit further includes a guide connector, which is used to connect the bottom shell and the limiting shell, and is used to guide the measuring shell and adjust the axial movable range of the measuring shell.

[0010] As a further preference, the guide connecting member includes a support rod, both ends of which are threadedly connected to the bottom shell and the limiting shell respectively, and the measuring shell is axially slidably sleeved on the middle part of the support rod.

[0011] As a further preference, the elastic member includes a tension spring, two ends of the tension spring are respectively connected to the measuring housing and the limiting housing, and the tension spring is in a pre-tensioned state.

[0012] As a further preference, the spacing positioning portion includes a detachable positioning ring, and the outer peripheral surface of the positioning ring is provided with a limiting piece for inserting into the gap to be measured.

[0013] As a further preferred embodiment, the probe further includes a thrust module, which is used to apply pressure to the measuring shell so that the measuring shell and the bottom shell are pressed together.

[0014] As a further preference, the measuring shell and the limiting shell are both cylindrical in shape, and the thrust module includes a push rod, which can pass through the limiting shell and push the measuring shell to move toward the bottom shell.

[0015] The second aspect of the present application provides a measurement system that adopts the following technical solution: A measurement system includes any one of the pencil-type fiber spectral interferometry distance measurement probes described in the first aspect, and further includes a detection light source, an optical module, a photoelectric detection module, and a signal acquisition module, wherein: The detection light source is used to output a light signal; The optical module is used to transmit the optical signal to the measuring unit of the pencil-type optical fiber spectral interferometry distance measurement probe, so that the measuring unit generates an interference optical signal based on the optical signal, and the optical module is also used to transmit the interference optical signal to the photoelectric detection module; The photoelectric detection module is used to convert the interference light signal into an electrical signal; The signal acquisition module is used to collect data on the electrical signal.

[0016] In general, the above technical solutions conceived by this application have the following technical advantages compared with the existing technologies: 1. This application designs a pen-type fiber optic spectral interferometry distance measurement probe. The probe uses a fiber optic Michelson interferometer as a sensitive structure to measure the gap using a spectral interferometry measurement method. Compared with traditional mechanical measurement schemes, the probe designed in this paper has the advantages of high measurement accuracy and high reliability.

[0017] 2. The probe designed in this application is in the shape of a pen. The distance measurement can be achieved by inserting the upper and lower limit plates into the gap and pressing and releasing them to adjust. Under this design, the probe has the advantages of small size, easy operation and high reliability, and can perform distance detection in narrow environments.

[0018] 3. In this design, by adjusting the length of the support rod, tension spring and T-type telescopic switch, the measuring arm length of the Michelson interferometer can be flexibly controlled, so that the probe has a larger measurement range. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the overall structure of a pencil-type optical fiber spectral interferometry distance measurement probe provided in an embodiment of the present application; Figure 2 This is a cross-sectional view of a pencil-type optical fiber spectral interferometry distance measurement probe provided in an embodiment of the present application; Figure 3 This is an exploded view of a pencil-type optical fiber spectral interferometry distance measurement probe provided in an embodiment of the present application; Figure 4 Schematic diagram of a Michelson interferometer composed of a pencil-type optical fiber spectral interferometry distance measurement probe provided in an embodiment of the present application; Figure 5 This is a comparison diagram of the initial state and working state of the pencil-type optical fiber spectral interferometry distance measurement probe provided in an embodiment of the present application measuring the pipeline flange gap; Figure 6 is a schematic diagram of a measurement system provided in an embodiment of the present application; Figure 7 This is a measurement diagram of a measurement system provided by an embodiment of the present application when the vertical distance is 2.000 mm; Figure 8 This is a measurement diagram of the measurement system provided in an embodiment of the present application when the vertical distance is 2.001 mm.

[0020] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1. Bottom shell; 2. Measuring shell; 3. Limiting shell; 4. Elastic part; 5. Fiber spectral interference module; 5-1. Optical fiber; 5-2. Collimator; 5-3. Cube beam splitter; 6. Reflection module; 7. Spacing positioning part 7; 7-1. Positioning ring; 7-2. Limiting piece; 7-3. Prism structure; 8. Support rod; 9. Push rod; 10. Detection light source; 11. Optical module; 12. Photoelectric detection module; 13. Signal acquisition module; 100. Pipe flange; 200. Measuring unit. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0022] The following is combined with Figures 1-8 This application is described in further detail.

[0023] The present application embodiment discloses a pencil-type optical fiber spectral interferometry distance measurement probe. Figure 1-Figure 4 The pen-type fiber spectral interferometry distance measurement probe includes an adjustment unit and a measurement unit 200. The adjustment unit is pen-shaped and comprises a bottom shell 1, a measurement shell 2, a limiting shell 3, and an elastic member 4. The bottom shell 1 is connected to the limiting shell 3, and the measurement shell 2 is axially movable between the bottom shell 1 and the limiting shell 3. The elastic member 4 is used to provide an elastic force to separate the measurement shell 2 from the bottom shell 1. The measurement unit 200 includes a fiber spectral interferometry module 5 and a reflection module 6. One of the fiber spectral interferometry module 5 and the reflection module 6 is disposed in the measurement shell 2, and the other is disposed in the bottom shell 1. The fiber spectral interferometry module 5 and the reflection module 6 constitute a Michelson interferometer. Both the bottom shell 1 and the measurement shell 2 are provided with spacing locating portions 7. Under the action of elastic force, the two spacing locating portions 7 are configured to adaptively abut against two opposing walls of the gap to be measured when released after being compressed and closed. This simultaneously drives the fiber spectral interferometry module 5 and the reflection module 6 away from each other, thereby changing the optical path difference of the Michelson interferometer. Based on the optical path difference, the distance between the two opposing walls of the gap can be determined.

[0024] Specifically, in some embodiments, the bottom shell 1, the measuring shell 2 and the limiting shell 3 are all cylindrical bodies with the same outer diameter, and the bottom shell 1, the measuring shell 2 and the limiting shell 3 are arranged in sequence along the axial direction, and the central axes of the three coincide. Figure 1 As shown, the probe is roughly in the shape of a pen. When the probe is placed vertically, the bottom shell 1 can serve as the lower shell of the probe, the measuring shell 2 can serve as the middle shell of the probe, and the limiting shell 3 can serve as the upper shell of the probe.

[0025] Furthermore, in some embodiments, the adjustment unit further includes a guide connector, which is used to connect the bottom shell 1 and the limiting shell 3 , and is used to guide the measuring shell 2 and adjust the axial movable range of the measuring shell 2 .

[0026] Furthermore, in some specific embodiments, both the bottom shell 1 and the limiting shell 3 are provided with axially extending threaded holes, and the shell of the measuring shell 2 is provided with a through hole coaxial with the threaded holes. The guide connection member includes, but is not limited to, a support rod 8. When the support rod 8 is used, its ends are threadedly connected to the bottom shell 1 and the limiting shell 3, respectively, and the measuring shell 2 is axially slidably sleeved on the middle portion of the support rod 8.

[0027] Specifically, one axial end of the support rod 8 is threadedly connected to the threaded hole in the bottom shell 1, and the other axial end of the support rod 8 is threadedly connected to the threaded hole in the limit shell 3. The support rod 8 is inserted into the through hole of the measuring shell 2, and the outer circumferential wall of the support rod 8 is in contact with the inner circumferential wall of the through hole. The support rod 8 is preferably a bidirectional threaded rod with a smooth outer circumferential surface in the middle and opposite threads at both ends. The two ends of the bidirectional threaded rod are respectively threadedly connected to the bottom shell 1 and the limit shell 3. In this case, the threads in the bottom shell 1 and the limit shell 3 have opposite threads.

[0028] Furthermore, a plurality of support rods 8 are arranged in parallel to improve the stability of the probe and reduce lateral interference. Figure 2 、 Figure 3 As shown, three support rods 8 are provided, evenly spaced along the circumference of the bottom shell 1. Correspondingly, three threaded holes are provided on the bottom shell 1 and the limiting shell 3, each at a 120-degree angle to the other. Three corresponding through holes are provided on the measuring shell 2. Preferably, the length of the support rods 8 is 100 mm to 120 mm.

[0029] Furthermore, in some other embodiments, the guide connector includes a connecting rod and a screw, wherein one axial end of the connecting rod is threadedly connected to the limiting shell 3, and the other axial end of the support rod is connected to the bottom shell 1 through a screw.

[0030] In this design, by setting up the support rod 8, the axial series connection between the bottom shell 1, the measuring shell 2, and the limit shell 3 can be achieved; and by adjusting the spiral connection depth or the body length of the support rod 8, the spacing between the bottom shell 1 and the limit shell 3 can be adjusted, thereby achieving the adjustment of the axial activity range of the measuring shell 2, and then achieving the adjustment of the probe measurement range; and the set support rod 8 can also guide the measuring shell 2, which is conducive to improving the measurement accuracy and stability.

[0031] Further, such as Figure 2As shown, in some embodiments, the elastic member 4 includes a tension spring, which is in a pre-tensioned state, one end of which is connected to the measuring housing 2, and the other end of which is connected to the limiting housing 3. Of course, in some other embodiments, the elastic member 4 can also be an elastic member such as a metal spring or an elastic rope.

[0032] In addition, in some embodiments, the elastic member 4 may also be provided between the measuring housing 2 and the bottom housing 1 . The elastic member 4 is preferably a compression spring, which is used to provide an elastic force to drive the measuring housing 2 and the bottom housing 1 away from each other.

[0033] Figure 2 As shown, in some specific implementations, the top of the limit shell 3 has a flange protruding inward, and a support platform is integrally formed on the inner side of the middle part of the measuring shell 2. The vertical cross-section of the measuring shell 2 is H-shaped, and the upper end of the tension spring is in conflict with the bottom wall of the flange, and the lower end of the tension spring is in conflict with the top surface of the support platform.

[0034] Furthermore, in some specific embodiments, the spacing positioning portion 7 includes a detachable positioning ring 7-1. The positioning ring 7-1 is preferably in a finger-ring structure, and the positioning ring 7-1 can be mounted on the outer circumference of the measuring housing 2 and the bottom housing 1. The positioning ring 7-1 can be connected to the measuring housing 2 and the bottom housing 1 by screws. The outer circumference of the positioning ring 7-1 is provided with a limit piece 7-2 for inserting into the gap to be measured.

[0035] Preferably, the outer periphery of the positioning ring 7-1 is also fixedly connected or integrally formed with a prism structure 7-3, which has a platform or surface for positioning the object to be measured to ensure that the limiting piece 7-2 extends into the gap between the objects parallel to the surface of the object to be measured.

[0036] The limiting pieces 7-2 are preferably thin sheets of uniform thickness, with the facing surfaces of the two limiting pieces 7-2 parallel to each other and capable of affixing to each other, and the facing surfaces of the two limiting pieces 7-2 parallel to each other. Preferably, the lower surface of the limiting piece 7-2 on the measuring housing 2 is flush with the lower surface of the measuring housing 2. The upper surface of the limiting piece 7-2 on the bottom housing 1 is flush with the upper surface of the bottom housing 1.

[0037] Furthermore, the bottom housing 1 is provided with an axially extending threaded hole, into which the reflector module 6 is threadedly connected. The reflector module 6 has a reflective surface facing the fiber spectral interferometer module 5. Preferably, the reflector module 6 includes a base knob, which is coaxial with the bottom housing 1 and threadedly connected to the base. The upper end surface of the base knob has a reflective film serving as the reflective surface. Preferably, the reflective film is a thin film material coated on the surface of the base knob, and the reflectivity of the thin film material is 0.04-1.

[0038] Furthermore, the optical fiber spectrum interference module 5 is arranged in the measurement shell 2, and the central axis of the optical fiber spectrum interference module 5 coincides with the central axis of the measurement shell 2. The optical fiber spectrum interference module 5 and the reflection module 6 are composed as follows: Figure 4 The Michelson interferometer shown in the figure uses spectral interferometry to measure gaps. Compared to traditional mechanical measurement, the resulting Michelson interferometer has the advantage of higher measurement accuracy. Preferably, the arm length of the Michelson interferometer is 3 mm to 13 mm. In some other embodiments, the fiber spectral interferometer module 5 can be disposed in the measurement housing 2, and the reflection module 6 can be correspondingly disposed in the bottom housing 1.

[0039] Further, such as Figure 2 、 Figure 3 As shown, the fiber spectral interferometer module 5 includes an optical fiber 5-1, a collimator 5-2, and a cubic beam splitter 5-3. The collimator 5-2 and the cubic beam splitter 5-3 are arranged axially, and the cubic beam splitter 5-3 is located at the end of the collimator 5-2 near the reflector module 6. The optical fiber 5-1 is connected to the collimator 5-2, and one end of the optical fiber 5-1 is threadedly embedded in a threaded hole on the side of the measurement housing 2 to connect the probe to the outside world.

[0040] Among them, optical fiber 5-1 is used to transmit the optical signal to collimator 5-2 for collimation. The collimated optical signal then reaches cubic beam splitter 5-3 and is split into reflected light and transmitted light. The transmitted light can be reflected back to cubic beam splitter 5-3 by reflection module 6 to form interference with the reflected light. That is, after the optical signal is transmitted to optical fiber 5-1, it can be transmitted to collimator 5-2 by optical fiber 5-1 for collimation. The collimated optical signal then reaches cubic beam splitter 5-3 and is split into reflected light and transmitted light. The transmitted light can be reflected back to cubic beam splitter 5-3 by reflection module 6 to form interference with the reflected light. By measuring the optical path difference in the interference, the spacing size can be determined.

[0041] Furthermore, the probe further comprises a thrust module, which is used to apply pressure to the measuring shell 2 so that the measuring shell 2 and the bottom shell 1 are pressed together. Figure 1 and Figure 2 As shown, the thrust module includes a push rod 9 , which can pass through the limiting shell 3 and push the support platform in the measuring shell 2 to move the measuring shell 2 toward the bottom shell 1 .

[0042] Among them, such as Figure 2-Figure 3As shown, the push rod 9 can be T-shaped to serve as a T-type telescopic switch. When the probe is placed upright, the upper and lower surfaces of the bottom housing 1, the measuring housing 2, the limit housing 3, the base knob, the T-type telescopic switch, and the limit plate 7-2 are all parallel to ensure that the distance between the upper limit plate 7-2 and the lower limit plate 7-2 is equal at all locations. Of course, in other embodiments, the thrust module can adopt other existing manual, electric, or pneumatic thrust components.

[0043] For ease of understanding, Figure 5 The initial and working diagrams of a pencil-type fiber optic spectral interferometry distance measurement probe for precise gap measurement measuring the gap of a pipe flange 100 are shown. For ease of understanding, arrows and markings are added to the diagram, where a downward arrow represents downward movement or stretching, and a horizontal line represents stationary.

[0044] When the pencil-type fiber optic spectral interferometry distance measurement probe is in operation, push rod 9 is pressed until the facing surfaces of the two limit plates 7-2 are in contact. Push rod 9 moves downward, pushing the measurement housing 2 and other structures downward, and the tension spring is stretched downward to its maximum tension. The prism structure 7-3 at the lower limit plate 7-2 and the limit plate 7-2 engage one side of the pipe flange 100. At this point, push rod 9 is released, and the elastic restoring force of the stretched tension spring causes the measurement housing 2 and its related fasteners to move upward until the upper limit plate 7-2 and the prism structure 7-3 engage the other side of the pipe flange 100. At this point, the gap in the pipe flange 100 can be measured by measuring the measuring arm length of the Michelson interferometer inside the pencil-type fiber optic spectral interferometry distance measurement probe.

[0045] In practice, in this embodiment, the size of the base housing 1, measuring housing 2, and limiting housing 3 essentially determines the size of the entire measurement system. The elastic deformation of the tension spring, as well as the lengths of the push rod 9 and support rod 8, determine the length of the Michelson interferometer's measuring arm (i.e., the measurable range of the gap between the pipe flanges 100). Pressing or releasing the push rod 9 changes the length of the Michelson interferometer's measuring arm (i.e., the distance between the two limiting plates 7-2). Theoretically, as long as the deformation of the tension spring (elastic element 4) remains within the elastic range, the measurement accuracy of the gap (i.e., the object gap) is solely dependent on the accuracy of the laser interferometer measurement.

[0046] The present application also discloses a measurement system, referring to Figure 6The measurement system includes an adjustment host and a pen-type fiber optic spectral interference distance measurement probe. The adjustment host further includes a detection light source 10, an optical module 11, a photoelectric detection module 12, and a signal acquisition module 13. The detection light source 10 is used to output an optical signal; the optical module 11 is used to transmit the optical signal to the measurement unit 200 in the pen-type fiber optic spectral interference distance measurement probe, so that the measurement unit 200 in the pen-type fiber optic spectral interference distance measurement probe generates an interference light signal based on the optical signal. The optical module 11 is also used to transmit the interference light signal to the photoelectric detection module 12; the photoelectric detection module 12 is used to convert the interference light signal into an electrical signal; and the signal acquisition module 13 is used to collect data from the electrical signal.

[0047] Specifically, in some embodiments, the light emitted by the detection light source 10 is input into the first port of the optical module 11, the input light of the first port is output through the second port, and the output light of the second port is transmitted to the measuring unit 200 of the pen-type optical fiber spectral interference distance measurement probe. A portion of the light signal transmitted to the measuring unit 200 is reflected by the splitting surface of the cubic beam splitter 5-3 of the optical fiber spectral interference module 5 and the reflection-enhancing film of the cubic beam splitter 5-3, and finally reflected by the splitting surface of the cubic beam splitter 5-3, and a portion is transmitted to the reflective film on the surface of the base knob. The light signal reflected by the reflective film is transmitted through the cubic beam splitter 5-3 and interferes with the light signal reflected by the cubic beam splitter 5-3 to form an interference light signal, and then the interference light signal is transmitted to the second port of the optical module 11, the input light of the second port is output through the third port of the optical module 11, and the output light of the third port is transmitted to the photoelectric detection module 12, and the light signal is converted into an electrical signal by the photoelectric detection module 12, and finally the electrical signal is collected by the signal acquisition module 13.

[0048] In the pencil-type fiber optic spectral interferometer probe, the fiber end face, the cubic beam splitter 5-3, and the reflective film on the surface of the base knob form a Michelson interferometer structure to read the gap size signal. The Michelson interferometer has weak lateral interference and a simple structure, so the gap measurement system has the advantages of high precision and low cost.

[0049] The light field emitted by the fiber optic spectrum interference module 5 can be expressed as:

[0050] The light field after two reflections by the cubic beam splitter 5-3 of the fiber optic spectral interference module 5 can be expressed as:

[0051] The light field reflected by the reflective film on the surface of the base knob and transmitted twice by the cubic beam splitter 5-3 of the optical fiber spectral interference module 5 can be expressed as:

[0052] The optical electric field output by the third port of the optical module 11 is:

[0053] Then the output light intensity of the photoelectric detection module is obtained as:

[0054] The spacing between the limiters obtained by wavelength demodulation is:

[0055] Finally, the gap size of the object to be measured is:

[0056] in, is the reflectivity of the beam splitting surface of the cubic beam splitter 5-3 in the fiber spectral interference module 5, 、 are the reflectivities of the coating surface of the cubic beam splitter 5-3 in the fiber spectral interference module 5 and the surface reflective film of the base knob, respectively. is the amplitude of the incident light, ω 0 represents the angular frequency of light, t Indicates time, n 0 represents the medium refractive index of the cubic beam splitter 5-3, λ represents the wavelength of light, is the initial phase of the incident light, is the phase of the interference light, h is the nearest neighbor distance from the surface of the cubic beam splitter 5-3 in the fiber optic spectral interference module 5 to the lower surface of the measurement shell 2, d To measure the vertical distance between the lower surface of the shell 2 and the surface reflective film of the base knob (such as Figure 4 (as indicated by the markings), d 0 is the thickness of the limiting piece 7-2.

[0057] The above output light intensity is regarded as the incident wave number Function, perform fast Fourier transform of space domain-wave number domain, and get the peak value at Fourier transform spatial spectrum curve at .

[0058] In the embodiment of the present application, the horizontal coordinate corresponding to the peak value of the Fourier transform spatial spectrum curve is the vertical distance between the lower surface of the measuring shell 2 and the surface reflective film of the base knob; plus 2 times the thickness of the thin film of the limit plate 7-2 d 0 to get the measured gap size value.

[0059] Further, Figure 7 、 Figure 8The interference spectrum and Fourier transform spectrum of a measurement system for precision gap measurement provided by an embodiment of the present invention are as follows. Specifically, Figure 7 (a) is the vertical distance between the lower surface of the measuring shell 2 and the surface reflective film of the base knob d The interference spectrum diagram when the diameter is 2.000mm, Figure 7 (b) is the vertical distance between the lower surface of the measuring shell 2 and the surface reflective film of the base knob d Fourier transform spectrum at 2.000 mm. "Wavelength" represents wavelength, and "Intensity" represents intensity.

[0060] Figure 8 (a) is the vertical distance between the lower surface of the measuring shell 2 and the surface reflective film of the base knob d The interference spectrum at 2.001mm, Figure 8 (b) is the vertical distance between the lower surface of the measuring shell 2 and the surface reflective film of the base knob d The Fourier transform spectrum diagram at 2.001mm, where FFT represents "amplitude"; Figure 7 and Figure 8 As shown, when the vertical distance d When the change is 0.001 mm, the interference spectrum and Fourier transform spectrum change significantly, indicating that the gap size change of 0.0001 mm can be detected.

[0061] The reflective coating on the base knob surface is preferably aluminum, which offers the advantages of thinness and low cost. Alternatively, it can be replaced with other coating materials or by bonding a reflector to the surface as needed. Because the fiber optic spectral interferometer module 5 is located at the central axis of the measurement housing 2, the reflective coating on the base knob surface can be appropriately reduced to suppress interference from external light fields.

[0062] Preferably, the limiting plate 7-2 can be made of a thin sheet of titanium steel composite material to ensure that the thin sheet is corrosion-resistant and not easily damaged. The thickness of the thin sheet is preferably 0.25 mm. For different gap measurements, different sheet shapes and sizes can be selected to meet the spacing measurement in different situations.

[0063] Preferably, the material of the support rod 8 can be beryllium bronze, which has the advantages of high strength, self-lubrication and corrosion resistance. These advantages ensure that the mid-end shell and its fasteners can slide along the support rod 8 with little friction, further improving the sensitivity of precision gap measurement; at the same time, the stability of the entire probe is better, reducing lateral interference.

[0064] Preferably, the detection light source 10 is a broad spectrum light source with a wavelength range of 1500 nm to 1600 nm. In addition, other detection light sources 10 can also be selected according to needs.

[0065] Preferably, the optical module 11 is a fiber circulator, which has the advantages of high return loss and low transmission loss, which helps reduce the measurement noise of the gap measurement system. The function of the optical module 11 is to input the laser light emitted by the laser into the measurement unit 200 of the pencil-type fiber spectral interferometry distance measurement probe, and then input the light signal reflected from the measurement unit 200 into the photodetector. Among common fiber optic devices, both fiber circulators and fiber couplers can achieve the above functions, but fiber circulators have high return loss and low transmission loss, which can reduce the measurement noise of the gap measurement system. In addition, other waveguide structures or other optical structures with the function of a fiber circulator can be replaced as needed. In addition, the photoelectric detection module 12 is preferably a spectrum analyzer.

[0066] It should be understood that expressions such as "include" and "may include" used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "include" and / or "have" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0067] It should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply 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 a limitation on the present application.

[0068] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0069] In this application, unless otherwise specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0070] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A pencil-type optical fiber spectral interferometry distance measurement probe, characterized in that: include: An adjustment unit, the adjustment unit being in the shape of a pen, comprising a bottom shell (1), a measuring shell (2), a limiting shell (3) and an elastic member (4), the bottom shell (1) being connected to the limiting shell (3), the measuring shell (2) being axially movable between the bottom shell (1) and the limiting shell (3), and the elastic member (4) being used to provide an elastic force for separating the measuring shell (2) from the bottom shell (1); The measuring unit (200) comprises a fiber optic spectrum interference module (5) and a reflection module (6), wherein one of the fiber optic spectrum interference module (5) and the reflection module (6) is arranged in the measuring housing (2), and the other is arranged in the bottom housing (1), and the fiber optic spectrum interference module (5) and the reflection module (6) constitute a Michelson interferometer; Wherein, the bottom shell (1) and the measuring shell (2) are both provided with spacing positioning parts (7). Under the action of the elastic force, the two spacing positioning parts (7) are configured to adaptively abut against two opposite wall surfaces of the gap to be measured when they are released after being compressed and closed, and at the same time drive the optical fiber spectrum interference module (5) and the reflection module (6) to move away from each other to change the optical path difference of the Michelson interferometer.

2. The pencil-type optical fiber spectral interferometry distance measurement probe according to claim 1, characterized in that: The bottom shell (1) is provided with a threaded hole extending through the bottom shell in the axial direction, the reflection module (6) is threadedly connected in the threaded hole, and the reflection module (6) has a reflection surface facing the optical fiber spectrum interference module (5).

3. The pencil-type optical fiber spectral interferometry distance measurement probe according to claim 1, characterized in that: The fiber optic spectrum interference module (5) comprises an optical fiber (5-1), a collimator (5-2) and a cubic beam splitter (5-3), wherein: The optical fiber (5-1) is used to transmit the optical signal to the collimator (5-2) for collimation, and then the collimated optical signal reaches the cubic beam splitter (5-3) and is split into reflected light and transmitted light; the transmitted light can be reflected back to the cubic beam splitter (5-3) through the reflection module (6) to form interference with the reflected light.

4. The pencil-type optical fiber spectral interferometry distance measurement probe according to claim 1, characterized in that: The adjustment unit further comprises a guide connecting member, which is used to connect the bottom shell (1) and the limiting shell (3), and is used to guide the measuring shell (2) and adjust the axial movable range of the measuring shell (2).

5. The pencil-type optical fiber spectral interferometry distance measurement probe according to claim 4, characterized in that: The guide connecting member comprises a support rod (8), the two ends of which are respectively threadedly connected to the bottom shell (1) and the limit shell (3), and the measuring shell (2) is axially slidably sleeved on the middle part of the support rod (8).

6. The pencil-type optical fiber spectral interferometry distance measurement probe according to claim 1, characterized in that: The elastic member (4) comprises a tension spring, the two ends of which are respectively connected to the measuring shell (2) and the limiting shell (3), and the tension spring is in a pre-tensioned state.

7. The pencil-type optical fiber spectral interferometry distance measurement probe according to claim 1, characterized in that: The spacing positioning portion (7) comprises a detachable positioning ring (7-1), and the outer peripheral surface of the positioning ring (7-1) is provided with a limiting piece (7-2) for inserting into the gap to be measured.

8. The pencil-type fiber optic spectral interferometry distance measurement probe according to any one of claims 1 to 7, characterized in that: The probe further comprises a thrust module, which is used to apply pressure to the measuring shell (2) so that the measuring shell (2) and the bottom shell (1) are pressed together.

9. The pencil-type optical fiber spectral interferometry distance measurement probe according to claim 8, characterized in that: The measuring shell (2) and the limiting shell (3) are both cylindrical in shape, and the thrust module comprises a push rod (9). The push rod (9) can pass through the limiting shell (3) and push the measuring shell (2) to move toward the bottom shell (1).

10. A measurement system, characterized in that: The invention comprises a pen-type optical fiber spectral interferometry distance measurement probe according to any one of claims 1 to 9, further comprising a detection light source (10), an optical module (11), a photoelectric detection module (12), and a signal acquisition module (13), wherein: The detection light source (10) is used to output a light signal; The optical module (11) is used to transmit the optical signal to a measuring unit (200) of a pencil-type optical fiber spectral interference distance measurement probe, so that the measuring unit (200) generates an interference optical signal based on the optical signal. The optical module (11) is also used to transmit the interference optical signal to a photoelectric detection module (12); The photoelectric detection module (12) is used to convert the interference light signal into an electrical signal; The signal acquisition module (13) is used to collect data on the electrical signal.

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