Optical fiber slit width detection device based on visible light

Abstract

The utility model relates to a visible light-based optical fiber slit width detection device, which belongs to the field of detection equipment, and comprises a semiconductor laser, the semiconductor laser emits visible light to enter a convex lens, and light beams are converged through the convex lens; the converged light beams enter a half-wave plate and a polarizing beam splitter to realize separation of P light and S light and light intensity adjustment; the adjusted light beam enters a first total reflective mirror and a second total reflective mirror and enters an optical attenuator through the first total reflective mirror and the second total reflective mirror, the light beam with attenuated light intensity enters a first optical fiber collimator, and the first optical fiber collimator is connected to an optical fiber coil to realize coupling of spatial light to optical fibers; the optical fiber coil is sequentially connected with a second optical fiber collimator, a digital camera and a computer; the whole device adopts common and cheap optical elements, so that the detection cost is reduced.

Description

Technical Field

[0001] The utility model relates to the field of detection equipment, in particular to an optical fiber slot width detection device based on visible light. Background Art

[0002] Seam width detection plays a vital role in the manufacturing industry, especially in quality control and manufacturing processes. Accurate seam width detection can ensure that product dimensions meet requirements and facilitate component assembly. It is particularly important in component processing and assembly.

[0003] Traditional manual detection methods for seam width are inaccurate due to differences in measuring calipers and human operation, affecting the precision of parts. In addition, manual online detection poses a significant safety hazard. Fiber optic sensing has the advantages of high precision, real-time operation, long-term stability, and resistance to electromagnetic interference, and can be used for real-time detection of seam width. The common fiber optic sensing method for detecting seam width uses fiber gratings as the sensing element and designs a sensor with a specific structure to detect the seam width in real time. However, the fiber grating seam width detection method uses a grating demodulator to demodulate the central wavelength of the fiber grating, making the cost of the entire detection system relatively high. Utility Model Content

[0004] Currently, in the field of optical fiber sensors, slot width detection mainly uses fiber Bragg gratings as sensing elements, and a specific sensing structure is designed to detect the slot width. However, this type of fiber Bragg grating slot width detection uses a grating demodulator to demodulate the central wavelength of the fiber Bragg grating, resulting in a high cost of the detection system. At least one aspect of the present application can solve the above problem. Specifically, a technical solution is designed for a visible light-based optical fiber slot width detection device. The technical solution adopted is as follows:

[0005] An optical fiber slot width detection device based on visible light comprises:

[0006] A semiconductor laser emits visible light, which enters a convex lens and converges the light beam through the convex lens. The converged light beam enters a half-wave plate and a polarization beam splitter to separate P light and S light and adjust the light intensity of the entire detection light path. The adjusted P light enters a first total reflection mirror and a second total reflection mirror, and then enters an optical attenuator through the first and second total reflection mirrors. The light beam with attenuated light intensity enters a first fiber collimator. The first fiber collimator is connected to a fiber coil to achieve coupling of spatial light to the fiber. The fiber coil is connected to a second fiber collimator, a digital camera, and a computer in turn. The fiber coil is wound with a step-index single-mode fiber. The second fiber collimator achieves coupling of the fiber to the spatial light. The coupled spatial light enters a CMOS camera, which detects changes in the light spot and, after connecting to a computer, displays a real-time picture of the light spot on the computer.

[0007] Preferably, the wavelength of the light emitted by the semiconductor laser is 633 nm, and the first fiber collimator and the second fiber collimator are both fixed aspheric fiber collimators.

[0008] Preferably, the digital camera is a CMOS camera.

[0009] Preferably, the first total reflection mirror and the second total reflection mirror reflect the spatial light beam and then inject the light beam into the first optical fiber collimator at the center of the lens of the first optical fiber collimator.

[0010] The utility model realizes the coupling of spatial visible light to optical fiber through the above-mentioned optical elements, and coils the optical fiber into an optical fiber coil, and then realizes the coupling of optical fiber to spatial visible light. The optical fiber coil is placed in the gap. The different squeezing conditions of the optical fiber coil under different gap widths correspond to different mode coupling conditions in the optical fiber. The size of the gap width can be obtained by sending the detected light spot image into an existing trained deep learning model (such as the YOLO11 model). The entire device uses ordinary and inexpensive optical elements, which reduces the overall detection cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural diagram of the utility model;

[0012] Figure 2-Figure 5 The following are the corresponding light spot diagrams when the slit width is 9cm, 8cm, 7cm, and 6cm.

[0013] In the figure, 1. semiconductor laser, 2. convex lens, 3. half-wave plate, 4. polarization beam splitter, 5. first total reflection mirror, 6. second total reflection mirror, 7. optical attenuator, 8. first fiber collimator, 9. fiber coil, 10. second fiber collimator, 11. digital camera, 12. computer. DETAILED DESCRIPTION

[0014] In order to clearly illustrate the technical features of this solution, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0015] In addition, in the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "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 invention 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 invention.

[0016] like Figure 1 As shown, the optical fiber slot width detection device based on visible light includes:

[0017] Semiconductor laser 1, the light emitted by semiconductor laser 1 enters convex lens 2, and the convex lens 2 converges the light beam, and the light spot becomes smaller; the converged light beam enters half-wave plate 3 and polarization beam splitter 4, realizes the separation of P light and S light and can realize the adjustment of light intensity; the adjusted P light enters the first total reflection mirror 5 and the second total reflection mirror 6, and enters the optical attenuator 7 after being reflected by the first total reflection mirror 5 and the second total reflection mirror 6. The light beam with attenuated light intensity enters the first fiber collimator 8, and the first fiber collimator 8 is connected to the optical fiber coil 9 to realize the coupling of spatial light to optical fiber. The optical fiber coil 9 has three turns and a diameter of ten centimeters. It is then connected to the second fiber collimator 10, the digital camera 11 and the computer 12 in sequence. The optical fiber coil here It is wound with a step-index single-mode optical fiber, and the second optical fiber collimator 10 realizes the coupling of the optical fiber to the spatial light. The coupled spatial light enters the CMOS camera, detects the changes in the light spot and connects it to the computer 12, and then presents a real-time picture of the light spot on the computer 12. Finally, the real-time picture is sent to the trained YOLO11 deep learning model to identify the light spot picture. In this application, the identified features are mainly the light spot intensity and position. The light spot intensity and position information are related to the degree of squeezing of the optical fiber coil 9. At the same time, the squeezing degree of the optical fiber coil 9 is related to the slit width. Therefore, the light spot picture is input into the YOLO11 deep learning model for identification, and the association between the slit width and the light spot image is established to obtain the slit width.

[0018] The above-mentioned step-index optical fiber adopts a light beam with a wavelength of 633nm. This is because when the incident light wavelength is 633nm, the normalized frequency of the corresponding light wave is greater than 2.4048. At this time, the light is transmitted in the form of multimode in the step-index single-mode optical fiber. In addition to the base membrane HE 11 It also stimulates TE 01 ,TM 01 、HE 21 The normalized frequency is an important structural parameter of optical fiber, which can characterize the number of propagation modes in the optical fiber. It is also called the fiber V value. Its calculation formula is V = (2πa) / λ * NA.

[0019] Where a is the fiber core radius, λ is the wavelength of light, and NA is the numerical aperture.

[0020] Assuming the fiber core radius is 4 μm and the numerical aperture is 0.11, compare the normalized frequencies at incident wavelengths of 1550 nm and 633 nm, denoted as V1500 and V633.

[0021]

[0022] From the above normalized frequency, we can see that V1500 < 2.4048. Therefore, light at this wavelength is transmitted in the optical fiber in the form of a base film. When the wavelength of the optical fiber reaches 633nm, the step-index single-mode fiber becomes a multimode fiber. The mode field distribution and group velocity of the high-order modes within it are different. The different modes interfere with each other, thus generating an interference pattern. This interference pattern is related to the degree of compression of the optical fiber coil 9. Therefore, a CMOS camera can be used to extract the light spot, and the slit width can be reflected by quantifying the changes in the light spot image.

[0023] The specific light spot image is identified by optimizing the existing YOLO11 deep learning model. This embodiment mainly identifies the intensity and position of the light spot. The trained YOLO11 deep learning model pre-establishes a connection between the light spot intensity and position information of the image and the slit width information. After obtaining the light spot image, the light spot image is sent to the YOLO11 deep learning model. Different light intensities and positions correspond to different slit widths, and the slit width size can be obtained.

[0024] In actual operation, the optical fiber coil 9 is squeezed horizontally into the gap. The degree of squeezing of the optical fiber coil 9 is different for different gap widths, and the corresponding bending radius on both sides of the optical fiber coil 9 is different. The narrower the gap, the smaller the bending radius on both sides. The driving current of the semiconductor laser 1 of the present application is 80mA, emitting a 633nm beam, and the length of the step-index single-mode fiber is 1m. The diameter of the optical fiber coil 9 is ten centimeters, and the optical fiber coil 9 has three turns. When the optical fiber coil 9 is squeezed horizontally into the narrow gaps with widths of 9cm, 8cm, 7cm, and 6cm, the CMOS camera measures the corresponding light spot pattern as follows Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, by observing the light spot image in the above figure, it can be seen that as the slit width decreases, the light spot intensity gradually decreases, and the light spot position shows a counterclockwise change trend. After processing the image through the YOLO11 deep learning model, the light spot image is intelligently recognized to obtain the corresponding slit width.

[0025] Furthermore, for the above-mentioned light source with a wavelength of 633nm, the above-mentioned first fiber collimator 8 and the second fiber collimator 10 are both fixed aspheric fiber collimators. The fixed aspheric fiber collimator has better performance at this specific wavelength and has a good spherical aberration elimination effect at this wavelength. At the same time, the lens is fixed, has no moving parts, has a compact structure and is not affected by device misalignment.

[0026] Furthermore, the digital camera 11 is a CMOS camera. CMOS can record visible light as an image of an electronic signal. In other embodiments, the CMOS camera can also be replaced by a CCD camera.

[0027] Furthermore, the first total reflection mirror 5 and the second total reflection mirror 6 reflect the spatial light beam and inject it into the first optical fiber collimator 8 at the center of the lens of the first optical fiber collimator 8, which can ensure the collimation and stability of the light beam.

[0028] The above specific implementation methods cannot be used as a limitation on the protection scope of the present utility model. For those skilled in the art, any replacement, improvement or transformation made to the implementation methods of the present utility model falls within the protection scope of the present utility model.

[0029] Anything not described in detail in the present invention is well known to those skilled in the art.

Claims

1. An optical fiber slot width detection device based on visible light, characterized in that: include: A semiconductor laser emits visible light that enters a convex lens, which converges the light beam. The converged light beam enters a half-wave plate and a polarization beam splitter to separate P light and S light and adjust the light intensity of the entire detection light path. The adjusted P light enters a first total-reflecting mirror and a second total-reflecting mirror, and enters an optical attenuator through the first and second total-reflecting mirrors. The light beam with attenuated light intensity enters a first fiber collimator, which is connected to a fiber coil to achieve coupling of spatial light to optical fiber. The fiber coil is also connected to a second fiber collimator, a digital camera, and a computer in sequence. The fiber coil is wound with a step-index single-mode optical fiber.

2. The optical fiber slot width detection device based on visible light according to claim 1, characterized in that: The wavelength of the light emitted by the semiconductor laser is 633 nm, and both the first fiber collimator and the second fiber collimator are fixed aspheric fiber collimators.

3. The optical fiber slot width detection device based on visible light according to claim 1 or 2, characterized in that: The digital camera is a CMOS camera.

4. The optical fiber slot width detection device based on visible light according to claim 1, characterized in that: The first total reflective mirror and the second total reflective mirror reflect the spatial light beam and then inject the light beam into the first optical fiber collimator at the center of the lens of the first optical fiber collimator.

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