Device and method for testing geometrical parameters of optical fiber

Abstract

The invention discloses an optical fiber geometric parameter testing device and method, and belongs to the technical field of optical fiber manufacturing. According to the testing device, a certain angle is formed between the irradiation direction of the illumination unit and the emergent end face of the to-be-tested optical fiber, and the illumination unit illuminates the emergent end face, so that the emergent end face is clearly imaged in the image acquisition unit; the parameter resolving unit is used for judging the boundary of the core layer and the cladding layer according to whether the difference between the gray values of the adjacent pixel points in the end face image is larger than a preset gray threshold value or not, and therefore optical fiber geometric parameters are deduced. According to the testing device, the imaging effect of the optical fiber end face image is enhanced by improving the illumination unit for illuminating the optical fiber emergent end face, and then the algorithm for testing the optical fiber geometric parameters is improved for the end face imaging effect. Therefore, the geometrical parameters of the optical fiber can be obtained without arranging an incident light source at the incident end of the to-be-measured optical fiber, and compared with the prior art, a series of components such as the incident light source and an incident collimating lens are reduced, so that the complexity of the device is reduced.

Description

Technical Field

[0001] The present application belongs to the field of optical fiber manufacturing technology, and more specifically, relates to a device and method for testing optical fiber geometric parameters. Background Art

[0002] Fiber geometry parameter testing is one of the important means to evaluate fiber performance. It mainly focuses on the geometric characteristics of optical fibers, such as cladding diameter, cladding non-circularity, core diameter, core non-circularity, core spacing, etc. These geometric characteristics have an important impact on the transmission performance of optical fibers. Through fiber geometry testing, we can understand the quality of optical fibers, determine whether optical fibers meet the use requirements, and provide important reference for the production and manufacturing of optical fibers.

[0003] At present, the structures of optical fiber geometry test equipment at home and abroad are similar, and they all have the problems of complex structure, large size, many components, high cost and difficult maintenance. At the same time, there are certain requirements for the length of the optical fiber to be tested, and it is impossible to test the optical fiber geometry parameters under specific conditions. In addition, the existing test equipment and test methods have fewer and more complex algorithms for testing multi-core optical fibers, and are prone to technical problems such as missed detection of fiber cores. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present application provides a device and method for testing optical fiber geometric parameters, which aims to solve the technical problem that the existing testing equipment and testing methods are too complicated.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides a testing device for optical fiber geometric parameters, the testing device comprising an illumination unit, an image acquisition unit and a parameter solving unit;

[0006] The lighting unit is located between the image acquisition unit and the optical fiber to be tested, and is used to illuminate the exit end face of the optical fiber to be tested. The illumination direction of the lighting unit and the exit end face form an angle of 30° to 60°, so that the exit end face is clearly imaged in the image acquisition unit;

[0007] The image acquisition unit is used to acquire an end face image of the emission end face;

[0008] The parameter solving unit is used to determine the boundary of the core layer and the cladding layer according to whether the difference between the gray values ​​of adjacent pixels in the end face image is greater than a preset gray threshold, thereby deriving the optical fiber geometric parameters.

[0009] Preferably, the angle between the irradiation direction of the lighting unit and the emission end face is 45±5°.

[0010] Preferably, the lighting unit is ring-shaped, and the center of the ring coincides with the extension line of the axis of the emission end face.

[0011] Preferably, the parameter solving unit is specifically used for:

[0012] Draw multiple core-seeking circles with gradually increasing diameters with the center of the end face image as the center;

[0013] Find the adjacent pixel points on the core-seeking circle whose grayscale value difference is greater than the grayscale threshold;

[0014] Each group of adjacent pixels found on the core-seeking circle is judged in a clockwise or counterclockwise order: if the grayscale value of one group of adjacent pixels changes from small to large, and the grayscale value of the next group of adjacent pixels changes from large to small, then the midpoints of the two groups of adjacent pixels are connected, and a fiber core is determined by the midpoint of the connecting line;

[0015] The ellipse fitting algorithm is used for all the determined fiber cores to obtain the geometric parameters of all the fiber cores.

[0016] Preferably, the parameter solving unit is used to find a core-finding circle that determines the largest number of fiber cores, and the fiber cores located on the core-finding circle are all the fiber cores in the optical fiber to be tested.

[0017] Preferably, the parameter solving unit is specifically used for:

[0018] Obtaining the grayscale values ​​of all pixels in the end face image, if the difference between the grayscale values ​​of adjacent pixels is greater than the grayscale threshold, the midpoint of the line connecting the adjacent pixels is the boundary point;

[0019] Connect the boundary points whose distance is less than a preset distance threshold to obtain the boundary line between the core layer and the cladding;

[0020] Based on the boundary line, an ellipse fitting algorithm is used to fit the geometric parameters of all core layers and cladding layers.

[0021] Preferably, the testing device further comprises a fixing unit, and the fixing unit is used to fix the optical fiber to be tested so that the emission end face of the optical fiber to be tested faces the center of the image acquisition unit.

[0022] In a second aspect, the present application provides a method for testing optical fiber geometric parameters, the method comprising the following steps:

[0023] Adjust the inclination angle of the lighting unit so that the angle between the irradiation direction and the output end face of the optical fiber to be tested is 30° to 60°, until the output end face is clearly imaged in the image acquisition unit;

[0024] Collecting an end face image of the output end face;

[0025] Draw multiple core-seeking circles with gradually increasing diameters with the center of the end face image as the center;

[0026] Find the adjacent pixel points on the core-seeking circle whose grayscale value difference is greater than a preset grayscale threshold;

[0027] Each group of adjacent pixels found on the core-seeking circle is judged in a clockwise or counterclockwise order: if the grayscale value of one group of adjacent pixels changes from small to large, and the grayscale value of the next group of adjacent pixels changes from large to small, then the midpoints of the two groups of adjacent pixels are connected, and a fiber core is determined by the midpoint of the connecting line;

[0028] The ellipse fitting algorithm is used for all the determined fiber cores to obtain the geometric parameters of all the fiber cores.

[0029] Preferably, in the test method, the inclination angle of the lighting unit is adjusted so that the angle between the irradiation direction and the output end face of the optical fiber to be tested is 45±5°, until the output end face is clearly imaged in the image acquisition unit.

[0030] Preferably, the method further comprises the step of finding a core-finding circle that determines the largest number of fiber cores, and the fiber cores located on the core-finding circle are all the fiber cores in the optical fiber to be tested.

[0031] In a third aspect, the present application provides an electronic device, comprising: a memory for storing programs; a processor for executing the programs stored in the memory, and when the program stored in the memory is executed, the processor is used to execute the method described in any possible implementation of the second aspect.

[0032] In a fourth aspect, the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method described in any possible implementation of the second aspect.

[0033] In a fifth aspect, the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method described in any possible implementation manner of the second aspect.

[0034] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:

[0035] (1) The test device of the present application tilts the lighting unit used to illuminate the optical fiber output end face at a certain angle, thereby achieving the effects of eliminating reflections, reducing shadows, highlighting the core layer and enhancing the imaging effect, so that the core-cladding boundary of the optical fiber output end face produces an obvious light and dark difference, thereby directly performing boundary identification and detection of the optical fiber core layer based on the imaging of the output end face. Therefore, the device of the present application no longer needs to set an incident light source at the incident end of the optical fiber to be tested. Compared with the existing optical fiber geometric parameter testing device, the device of the present application reduces a series of components such as the incident light source and the incident collimating lens, thereby reducing the complexity of the device.

[0036] (2) Based on the improvement of the test device, the present application has made corresponding improvements to the test method of optical fiber geometric parameters. The fiber core is determined by whether the difference in grayscale values ​​of adjacent pixels in the collected optical fiber end face image is greater than a preset grayscale threshold, and the core circle is further fitted to obtain the core layer size. The test method of the present application is simple and effective, especially suitable for multi-core optical fibers. It can realize the synchronous detection of geometric parameters of all fiber cores in the multi-core optical fiber without worrying about the possibility of missed fiber core detection.

[0037] (3) Since the test device of the present application simplifies and optimizes the light source located at the incident end of the optical fiber to be tested in the conventional test device, there is no need to consider the impact of the excessive length of the optical fiber to be tested on the light source, and there is no requirement for the length of the optical fiber to be tested, thereby expanding the adaptability of the test device and method of the present application to the use conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the structure of an optical fiber geometric parameter testing device provided in an embodiment of the present application.

[0039] Figure 2 It is a schematic diagram of an optical fiber core positioning method provided in an embodiment of the present application.

[0040] Figure 3 It is a schematic diagram of the ellipse fitting algorithm provided in the embodiment of the present application.

[0041] In all the drawings, the same reference numerals are used to represent the same elements or structures, including: 1, three-axis translation stage; 2, LED light strip; 3, tube mirror; 4, camera; 5, parameter solving unit. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0043] The terms "first" and "second" in the specification and claims herein are used to distinguish different objects rather than to describe a specific order of the objects. For example, the first fiber core and the second fiber core are used to distinguish different fiber cores rather than to describe a specific order of the fiber cores.

[0044] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0045] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more than two. For example, multiple core-seeking circles refer to two or more core-seeking circles, etc.; multiple fiber cores refer to two or more fiber cores, etc.

[0046] Next, the technical solutions provided in the embodiments of the present application are introduced.

[0047] Embodiment 1:

[0048] An optical fiber geometric parameter testing device proposed in the present application is used to test the geometric parameters of a multi-core optical fiber.

[0049] like Figure 1 As shown, it is a schematic diagram of the structure of a device for testing optical fiber geometric parameters provided in Example 1 of the present application, which includes a three-axis translation stage 1 as a fixing unit, an LED light strip 2 as a lighting unit, a tube lens 3 as an amplifying unit, a camera 4 as an image acquisition unit, and a parameter solving unit 5.

[0050] Among them, the three-axis translation stage 1 is used to fix the optical fiber to be tested. At the same time, by adjusting the front-to-back direction, left-to-right direction and height direction of the three-axis translation stage 1, the exit end face of the optical fiber to be tested fixed therein (it should be noted that in the present invention, the "exit" end face is not a functional limitation on the end face of the optical fiber, but is only used to distinguish the two ends of the optical fiber, and is different from the prior art that the test of optical fiber geometric parameters requires the introduction of test devices at both ends of the optical fiber) is directly opposite to the center of the image acquisition unit, that is, the extended axis of the exit end face coincides with the center of the image acquisition unit. In this embodiment, the center of the image acquisition unit is also the center of the camera 4 viewfinder.

[0051] The LED light strip 2 is located between the three-axis translation stage 1 and the tube lens 3, and is used to illuminate the exit end face. The LED light strip 2 is annular and forms an annular aperture when illuminated. The illumination direction of the LED light strip 2 forms a 45° angle with the exit end face of the optical fiber to be tested. The inclination angle of the plane where the LED light strip 2 is located can be fine-tuned by ±5°. The center of the LED light strip 2 coincides with the extension line of the axis of the exit end face of the optical fiber to be tested.

[0052] In the embodiment of the present application, tilting the lighting unit, that is, the LED light strip 2, by 45±5° can bring the following advantages:

[0053] 1. Eliminate reflection: Direct illumination may cause high light reflection on the end surface, blocking the features of the core layer. By tilting the LED light, the angle of the reflected light can avoid direct vision of the camera, thus reducing the impact of reflection;

[0054] 2. Reduce shadows: It can reduce the shadow effects caused by the end face or surrounding environment;

[0055] 3. Highlight core layer: The function is to make the light hitting the end face of the optical fiber enter the cladding and core layer at different angles. Due to the different refractive indices of the core and cladding glass, part of the light entering the cladding will be refracted into the core layer. The light entering the core layer will not return to the cladding due to total reflection, so that the core and cladding are illuminated at the same time and the core layer is brighter. The end face image obtained by the camera will clearly show the cladding and core layer images;

[0056] 4. Enhancement effect: Oblique lighting can highlight the texture and contour of the sample surface, enhance the depth and three-dimensional sense in the image, make the core layer features more obvious, and facilitate subsequent analysis and processing.

[0057] Thus, the camera 4 can capture a clear end face image with distinct layers of the core layer and the cladding layer, and directly perform optical fiber geometric dimension detection based on the end face image, thereby simplifying the light source that illuminates the incident end of the optical fiber to be tested and related components such as collimating lenses.

[0058] Since the LED light strip 2 as a lighting unit is supported and tilted by a mechanical structure, there may be certain mechanical errors. Therefore, it is necessary to adjust the LED light strip 2 by ±5° according to the clarity of the image of the output end face in the camera, so that the output end face can be clearly imaged in the camera 4.

[0059] The tube lens 3 is located between the LED light strip 2 and the camera 4. It is used to magnify the end face imaging of the emission end face. In this embodiment, the magnification of the tube lens 3 is adjustable.

[0060] The camera 4 is located at the rear end of the tube lens 3 and is used to collect the end face image of the output end face after magnification;

[0061] The parameter calculation unit 5 reads the end face image from the camera 4, performs noise reduction preprocessing on the end face image, and then completes the optical fiber geometric parameter test based on the end face image. Figure 2 As shown:

[0062] Draw multiple core-seeking circles with gradually increasing diameters with the center of the end face image as the center.

[0063] Find the adjacent pixels on the core-seeking circle whose grayscale value difference is greater than the preset grayscale threshold; Figure 2 There are multiple groups of adjacent pixel points A1, B1, A2, B2, A3, B3, A4 and B4, wherein the difference in grayscale values ​​between two adjacent pixel points in each group of pixel points is greater than a preset grayscale threshold.

[0064] Judge each group of adjacent pixels found on the core-seeking circle in clockwise or counterclockwise order: if the grayscale value of one group of adjacent pixels changes from small to large, and the grayscale value of the next group of adjacent pixels changes from large to small, then connect the midpoints of the two groups of adjacent pixels and determine a fiber core by the midpoint of the connecting line. Figure 2As shown, each group of adjacent pixels found on the core-finding circle is judged in a clockwise order: the grayscale values ​​of the adjacent pixels in group A1 are from small to large, and the grayscale values ​​of the adjacent pixels in group B1 are from large to small. Then the midpoints a1 and b1 of the two groups of adjacent pixels A1 and B1 are connected, and the midpoint C1 of the line a1 and b1 must be located in a core, so point C1 determines the first core.

[0065] Similarly, the second fiber core is determined by two groups of adjacent pixel points A2 and B2. The third fiber core is determined by two groups of adjacent pixel points A3 and B3. The fourth fiber core is determined by two groups of adjacent pixel points A4 and B4.

[0066] Repeat the above core locating operation in multiple core-finding circles, find the core-finding circle with the most cores to determine all the cores in the multi-core optical fiber, and then use the ellipse fitting algorithm to fit all the core circles to obtain the center coordinates, core layer diameter and other geometric parameters.

[0067] The following describes how to fit the core circle where point C1 is located:

[0068] In this embodiment, the pixel of the image acquisition unit, that is, the camera, is 500W. Figure 3 The area of ​​the pixel point in the image captured by the camera is much smaller than the area of ​​the fiber core, that is, the higher the pixel, the higher the accuracy of the present application scheme, and the image acquisition unit with high pixel can be selected as much as possible according to the test accuracy. After the image acquisition unit is imaged, the area of ​​the fiber core in the image is at least 100 times the pixel area.

[0069] like Figure 3 As shown: First, take the green point C1 as the center and the preset radius value as the radius to draw a green perfect circle including the core circle;

[0070] Draw 16 blue radii in a perfect circle, with the angles between adjacent radii being the same;

[0071] On each radius, adjacent pixels are judged from the center of the circle outward in turn. If the difference in the grayscale values ​​of adjacent pixels is greater than the preset grayscale threshold for the first time, and the grayscale values ​​of adjacent pixels are decreasing from large to small, the pixel X1 with the larger grayscale value is recorded;

[0072] Similarly, find 16 yellow pixels from 16 radii: X1 to X16;

[0073] Ellipse fitting is performed on the 16 yellow pixel points X1 to X16, and the ellipse obtained by fitting is the fiber core circle.

[0074] Embodiment 2:

[0075] A fiber geometric parameter testing device similar to that in Example 1 is used to test the geometric parameters of a multi-core optical fiber. The difference from the device in Example 1 is that in the device of this embodiment, the irradiation direction of the LED light strip 2 forms an angle of 30° with the emitting end face of the optical fiber to be tested.

[0076] Embodiment 3:

[0077] A fiber geometric parameter testing device similar to that in Example 1 is used to test the geometric parameters of a multi-core optical fiber. The difference from the device in Example 1 is that in the device of this embodiment, the irradiation direction of the LED light strip 2 forms an angle of 60° with the emitting end face of the optical fiber to be tested.

[0078] Embodiment 4:

[0079] The optical fiber geometric parameter testing method proposed in this application is used to test the geometric parameters of a multi-core optical fiber. The method of this embodiment includes the following steps:

[0080] S1. Adjust the inclination angle of the lighting unit so that the angle between the irradiation direction and the output end face of the optical fiber to be tested is 45±5°, until the output end face is clearly imaged in the image acquisition unit;

[0081] S2, collecting an end face image of the emission end face;

[0082] S3, drawing multiple core-seeking circles with gradually increasing diameters with the center of the end face image as the center;

[0083] S4, finding the adjacent pixel points on the core-seeking circle whose grayscale value difference is greater than a preset threshold;

[0084] S5, judging each group of adjacent pixel points found on the core-seeking circle in a clockwise or counterclockwise order: if the grayscale value of one group of adjacent pixel points changes from small to large, and the grayscale value of the next group of adjacent pixel points changes from large to small, then connecting the midpoints of the two groups of adjacent pixel points, and determining a fiber core by the midpoint of the connecting line;

[0085] S6, finding a core-finding circle that determines the most fiber cores, and the fiber cores located on the core-finding circle are all the fiber cores of the optical fiber to be tested;

[0086] S7. Use an ellipse fitting algorithm for all located fiber cores to obtain geometric parameters of all fiber cores.

[0087] Embodiment 5:

[0088] The geometric parameters of the multi-core optical fiber are tested using a fiber geometric parameter testing method similar to that in Example 4. The difference from the method in Example 4 is that in the method of this embodiment, the inclination angle of the lighting unit is adjusted so that the angle between the irradiation direction and the output end face of the optical fiber to be tested is 60°, and the output end face is imaged in the image acquisition unit.

[0089] Embodiment 6:

[0090] The geometric parameters of the multi-core optical fiber are tested using a similar optical fiber geometric parameter testing method as in Example 4. The difference from the method in Example 4 is that in the method of this embodiment, the inclination angle of the lighting unit is adjusted so that the angle between the irradiation direction and the output end face of the optical fiber to be tested is 30°, and the output end face is imaged in the image acquisition unit.

[0091] It should be understood that the method in the above embodiment can be applied to the device introduced in embodiment 1. It can also be used in other optical fiber geometric parameter testing devices.

[0092] Based on the method in the above embodiment, an embodiment of the present application provides an electronic device, which may include: a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus. The processor may call the logic instructions in the memory to execute the method in the above embodiment.

[0093] In addition, the logic instructions in the above-mentioned memory can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application.

[0094] Based on the method in the above embodiment, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method in the above embodiment.

[0095] Based on the method in the above embodiment, an embodiment of the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method in the above embodiment.

[0096] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0097] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC.

[0098] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a storage medium or transmitted through the storage medium. The computer instructions may be transmitted from a website site, a computer, a server or a data center to another website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The storage medium may be any available medium that a computer can access or a data storage device such as a server or a data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid state disk (SSD)), etc.

[0099] It should be understood that the various numerical numbers involved in the embodiments of the present application are only used for the convenience of description and are not used to limit the scope of the embodiments of the present application.

[0100] The above content is easily understood by those skilled in the art. The above description 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 protection scope of the present application.

Claims

1. A test device for optical fiber geometric parameters, characterized in that: The testing device comprises an illumination unit, an image acquisition unit and a parameter solving unit; The lighting unit is located between the image acquisition unit and the optical fiber to be tested, and is used to illuminate the exit end face of the optical fiber to be tested. The illumination direction of the lighting unit and the exit end face form an angle of 30° to 60°, so that the exit end face is clearly imaged in the image acquisition unit; The image acquisition unit is used to acquire an end face image of the emission end face; The parameter solving unit is used to determine the boundary of the core layer and the cladding layer according to whether the difference between the gray values ​​of adjacent pixels in the end face image is greater than a preset gray threshold, thereby deriving the optical fiber geometric parameters.

2. The testing device according to claim 1, characterized in that: The irradiation direction of the illuminating unit and the emission end face form an angle of 45±5°.

3. The testing device according to claim 1, characterized in that: The lighting unit is in the shape of a ring, and the center of the ring coincides with the extended line of the axis of the emission end face.

4. The testing device according to claim 1, characterized in that: The parameter solving unit is specifically used for: Draw multiple core-seeking circles with gradually increasing diameters with the center of the end face image as the center; Find the adjacent pixel points on the core-seeking circle whose grayscale value difference is greater than the grayscale threshold; Each group of adjacent pixels found on the core-seeking circle is judged in a clockwise or counterclockwise order: if the grayscale value of one group of adjacent pixels changes from small to large, and the grayscale value of the next group of adjacent pixels changes from large to small, then the midpoints of the two groups of adjacent pixels are connected, and a fiber core is determined by the midpoint of the connecting line; The ellipse fitting algorithm is used for all the determined fiber cores to obtain the geometric parameters of all the fiber cores.

5. The testing device according to claim 4, characterized in that: The parameter solving unit is used to find a core-finding circle with the most fiber cores, and the fiber cores located on the core-finding circle are all the fiber cores in the optical fiber to be tested.

6. The testing device according to claim 1, characterized in that: The parameter solving unit is specifically used for: Obtaining the grayscale values ​​of all pixels in the end face image, if the difference between the grayscale values ​​of adjacent pixels is greater than the grayscale threshold, the midpoint of the line connecting the adjacent pixels is the boundary point; Connect the boundary points whose distance is less than a preset distance threshold to obtain the boundary line between the core layer and the cladding; Based on the boundary line, an ellipse fitting algorithm is used to fit the geometric parameters of all core layers and cladding layers.

7. The testing device according to claim 1, characterized in that: The testing device further comprises a fixing unit, which is used to fix the optical fiber to be tested so that the emission end face of the optical fiber to be tested faces the center of the image acquisition unit.

8. A method for testing optical fiber geometric parameters, characterized in that: The testing method specifically comprises the following steps: Adjust the inclination angle of the lighting unit so that the angle between the irradiation direction and the output end face of the optical fiber to be tested is 30° to 60°, until the output end face is clearly imaged in the image acquisition unit; Collecting an end face image of the output end face; Draw multiple core-seeking circles with gradually increasing diameters with the center of the end face image as the center; Find the adjacent pixel points on the core-seeking circle whose grayscale value difference is greater than a preset grayscale threshold; Each group of adjacent pixels found on the core-seeking circle is judged in a clockwise or counterclockwise order: if the grayscale value of one group of adjacent pixels changes from small to large, and the grayscale value of the next group of adjacent pixels changes from large to small, then the midpoints of the two groups of adjacent pixels are connected, and a fiber core is determined by the midpoint of the connecting line; The ellipse fitting algorithm is used for all the determined fiber cores to obtain the geometric parameters of all the fiber cores.

9. The testing method according to claim 8, characterized in that: In the test method, the tilt angle of the lighting unit is adjusted so that the angle between the irradiation direction and the output end face of the optical fiber to be tested is 45±5°, until the output end face is clearly imaged in the image acquisition unit.

10. The testing method according to claim 8, characterized in that: The method further comprises the step of finding a core-finding circle that determines the most fiber cores, and the fiber cores located on the core-finding circle are all the fiber cores in the optical fiber to be tested.

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