A beam shaping unit, an image transmission optical fiber crosstalk rate testing device and method

Abstract

This application belongs to the field of crosstalk detection technology, and specifically discloses a beam shaping unit, an image transmission optical fiber crosstalk rate test device and method. Through this application, combined with a beam adjustment device and an infinite imaging system, the laser beam is subjected to two beam shaping operations, so that the spot size coupled into the input end of the optical fiber to be tested can be reduced to 1.5 μm and smaller, and supports the arbitrary selection of suitable optical elements according to the core diameter of the optical fiber to be tested, with strong selectivity; this application specifically designs the focal length and / or diameter of each optical element, so that the spot coupled into the transmission pixel is smaller than the transmission pixel diameter, avoiding factors that affect crosstalk detection from the source, and having a good detection effect. Moreover, it can be arbitrarily switched to laser spots of different sizes, with simple operation, and is suitable for detecting different types of image transmission optical fibers.

Description

Technical Field

[0001] The present application belongs to the technical field of crosstalk detection, and more specifically, relates to a beam shaping unit, an image transmission optical fiber crosstalk rate testing device and method. Background Art

[0002] Image-transmitting fiber is a passive optical device widely used in image transmission, featuring excellent flexibility and bendability. Compared to traditional optical imaging equipment, its advantages include lightness, compact size, flexibility, and the ability to transmit images of complex spatial structures. These characteristics have led to its widespread application in fields such as medicine, scientific research, industry, military affairs, and aerospace. In an image-transmitting fiber, each fiber core can be considered an independent sampling point, responsible for carrying a corresponding image element. The size of the image element is determined by the diameter of a single fiber core, while the number of image elements at the end face of the image-transmitting fiber is proportional to the number of cores. Thanks to the unique manufacturing process of the image-transmitting fiber, the core positions at its input and output ends correspond exactly, ensuring distortion-free image transmission. Therefore, as a key component of a fiber-optic image transmission system, the characteristics of the image-transmitting fiber directly impact the performance of the entire system. The key parameters for evaluating the characteristics of an image-transmitting fiber include transmittance, resolution, and crosstalk. Transmittance is determined by both the transmittance of the single-core preform and the fill factor of the imaging fiber; resolution is related to the diameter of a single fiber core and the spacing between adjacent cores. The finer the core diameter and the smaller the core spacing, the higher the resolution. Crosstalk refers to the phenomenon where, when light of a certain intensity is coupled into a core at the input end of an imaging fiber, adjacent cores of the same core at the output end also exhibit a certain intensity, resulting in light coupling from one core to an adjacent core. This phenomenon significantly impacts the quality of images transmitted by imaging fibers, especially when the core size is small, where the crosstalk becomes more severe and the crosstalk rate increases. Therefore, how to effectively evaluate the crosstalk characteristics of imaging fibers has become a pressing research issue.

[0003] Existing crosstalk testing methods and devices are all targeted at multi-core optical fiber crosstalk testing. Patent CN115250144 A discloses a method and device for visualizing the coupling and large dynamic range crosstalk testing of multi-core optical fibers. This method simultaneously focuses the incident coupling light on the surface of the multi-core optical fiber's head end through a high-power objective lens. At the tail end of the multi-core optical fiber, illumination light with a wider divergence angle is then focused on its surface through a low-power objective lens, covering the entire cladding. At the head end, all the fiber cores illuminated by the illumination beam and the light spot reflected from the incident beam on the optical fiber surface can be observed. The optimal coupling effect is achieved by adjusting the incident light spot to the target fiber core and matching the spot size with the core size. Finally, crosstalk testing is achieved by measuring the grayscale value of the light field intensity obtained at different camera exposure times. This method requires that individual cores be distinguished at the head end when coupling illumination light to the entire end face of a multi-core optical fiber. A certain distance exists between the cores of a multi-core optical fiber. However, an imaging optical fiber contains thousands to tens of thousands of cores, which are closely spaced. When the entire end face of the optical fiber is illuminated, individual cores cannot be distinguished at the head end. Therefore, this method is not suitable for crosstalk detection of imaging optical fibers. Patent CN114707104A discloses a multi-core optical fiber crosstalk detection method, equipment, device, and computer storage medium. Patent CN113837120A discloses a multi-core optical fiber crosstalk monitoring method and system based on a neural network. Patent CN112733073A discloses a multi-core optical fiber crosstalk detection method based on coupled power theory. Patent CN110445534A discloses a method, system, and device for determining the crosstalk value of a multi-core optical fiber. The above patents all design crosstalk detection methods based on the theory of energy coupling between fiber cores. However, the core diameter of a multi-core optical fiber is generally 8 microns, and the distance between the cores is generally 43 microns. The cores of an imaging fiber are very densely distributed, with the distance between the cores not exceeding 10 microns and the core diameter not exceeding 5 microns. Therefore, traditional coupling methods cannot effectively detect crosstalk in imaging fibers. Summary of the Invention

[0004] In response to the defects of the existing technology, the purpose of this application is to provide a beam shaping unit, an image transmission fiber crosstalk rate testing device and method, aiming to solve the problem that due to the large number and density of image transmission fiber cores and the small core diameter, the traditional coupling method cannot effectively detect the image transmission fiber crosstalk, and it is impossible to use fan-in and fan-out devices like conventional multi-core optical fibers to lead out each fiber core with an independent optical fiber jumper.

[0005] A first aspect of the present application relates to a beam shaping unit, which comprises, in sequence along an optical path: a first lens, a beam adjustment device, a second lens, a third lens, and an infinite imaging system;

[0006] The first lens is used to couple the incident light into the beam adjustment device;

[0007] The beam adjusting device is used to adjust the beam diameter from a large beam diameter to a small beam diameter;

[0008] The second lens is used to restore the light beam with a reduced diameter to parallel light;

[0009] The third lens is used to introduce the parallel light with a reduced diameter into the parallel optical path stage of the infinite imaging system, while ensuring that the coaxial light of the infinite imaging system can still pass through;

[0010] The infinite imaging system is used to adjust the beam diameter again to match the core diameter of the optical fiber to be measured.

[0011] In one illustrated embodiment, the center of the incident light is coaxial with the first lens, the input end of the beam shaping device is located on the focal plane of the first lens, and the output end is located on the focal plane of the second lens.

[0012] In one embodiment, the following conditions are satisfied between the parameters: ,in, is the focal length of the second lens, is the focal length of the objective lens in the infinite imaging system, is the diameter of the small beam after adjustment, is the core diameter of the fiber to be measured.

[0013] In one illustrated embodiment, the beam adjustment component is a special optical fiber component or an aperture.

[0014] In one illustrated embodiment, the specialty optical fiber component is a mode field adapter.

[0015] In one illustrated embodiment, the relationship between the first lens and the mode field adapter is as follows: ,in, is the large mode field diameter of the mode field adapter, is the spot diameter of the incident beam, is the focal length of the first lens.

[0016] In one illustrated embodiment, the infinite imaging system is further used to visually couple the beam-shaped laser beam into a certain transmission pixel at the input end of the optical fiber to be tested.

[0017] A second aspect of the present application relates to a device for testing the crosstalk rate of an image-transmitting optical fiber, the device comprising a laser, a beam shaping unit according to any embodiment of the present application, a light intensity detection unit, and a processing unit;

[0018] a laser, for emitting a parallel beam of light;

[0019] A beam shaping unit is used to adjust the spot diameter of the incident parallel light beam so that it does not exceed the diameter of a single pixel of the image transmission fiber to be measured, and couple the shaped parallel light beam into a pixel at the input end of the image transmission fiber to be measured, where the input end of the image transmission fiber to be measured is located on the focal plane of the infinite imaging system;

[0020] The light intensity detection unit is used to detect the luminous intensity of the stimulated transmission pixel and the adjacent transmission pixel;

[0021] The processing unit is used to calculate the sum of the light intensities of the stimulated transmitting pixel and the adjacent transmitting pixel, and calculate the ratio of the total light intensity of the adjacent transmitting pixel to the sum as the crosstalk rate.

[0022] In one illustrated embodiment, the laser emission spot is a circular spot.

[0023] A third aspect of the present application relates to a method for testing the crosstalk rate of an image transmission optical fiber, which is implemented according to a crosstalk rate testing device of any embodiment of the present application. The crosstalk rate testing method includes:

[0024] S1. Turn on the laser and emit a parallel beam to the beam shaping unit;

[0025] S2. Using an infinity imaging system, ensure that the shaped parallel beam is coupled into a pixel at the input end of the image transmission fiber to be measured.

[0026] S3. Obtain the luminous intensity of the stimulated transmission pixel and the adjacent transmission pixel;

[0027] S4. Calculate the sum of the light intensities of the stimulated transmitting pixel and the adjacent transmitting pixel, and calculate the ratio of the total light intensity of the adjacent transmitting pixel to the sum as the crosstalk rate.

[0028] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies:

[0029] (1) This application proposes a beam shaping unit that performs two-stage beam shaping on the laser beam by combining a beam adjustment device with an infinite imaging system, so that the spot size coupled into the input end of the optical fiber to be tested can be reduced to 1.5 μm or smaller. It supports the arbitrary selection of suitable special optical fiber devices, lenses, and microscope objectives according to the core diameter of the optical fiber to be tested, with simple operation and strong selectivity.

[0030] (2) This application proposes a device and method for testing the crosstalk rate of an image transmission optical fiber. The output end of a special optical fiber device, the focal length of a rear lens, the focal length of a microscope objective lens, and the diameter of a transmission pixel are specifically designed so that the light spot coupled into the transmission pixel is smaller than the diameter of the transmission pixel. This avoids factors that affect crosstalk detection from the source, resulting in a good detection effect. Moreover, the device can be switched to laser spots of different sizes at will, is easy to operate, and is suitable for detecting different types of image transmission optical fibers. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the structure of the beam shaping unit provided in an embodiment of the present application.

[0032] Figure 2 Schematic diagram of the two end faces of the special optical fiber device provided for the implementation of this application.

[0033] Figure 3 Schematic diagram of the structure of the image transmission optical fiber crosstalk rate testing device provided in an embodiment of the present application.

[0034] Figure 4 Schematic diagram of the image transmission optical fiber structure provided in an embodiment of the present application.

[0035] Figure 5 Schematic diagram of the end face crosstalk of the image-transmitting optical fiber to be measured provided in an embodiment of the present application.

[0036] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0037] 1 is the first lens, 2 is the beam adjustment device, 3 is the second lens, 4 is the third lens, 5 is the infinity imaging system, 6 is the laser, 7 is the light intensity detection unit, 8 is the processing unit, 9 is the image transmission fiber to be measured, 21 and 23 are the fiber cores, 22 and 24 are the claddings, 51 is the CCD, 52 is the tube lens, 53 is the microscope imaging software, 54 is the microscope objective lens, 91 is the image transmission element, 92 is the outer cladding, and 93 is the common cladding. DETAILED DESCRIPTION

[0038] 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.

[0039] The term "and / or" as used herein describes an association between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. The symbol " / " as used herein indicates that the related objects are in an "or" relationship, for example, A / B means either A or B.

[0040] The terms "first" and "second" in this specification and claims are used to distinguish different objects rather than to describe a specific order of objects. For example, "first response message" and "second response message" are used to distinguish different response messages rather than to describe a specific order of response messages.

[0041] In the embodiments of this 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 this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0042] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more, for example, multiple processing units means two or more processing units, etc.; multiple elements means two or more elements, etc.

[0043] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0044] like Figure 1 As shown, the present application provides a beam shaping unit, which includes, along the optical path, a first lens 1, a beam adjustment device 2, a second lens 3, a third lens 4 and an infinite imaging system 5;

[0045] The first lens 1 is used to couple the incident light into the beam adjustment device 2;

[0046] The beam adjusting device 2 is used to adjust the beam diameter from a large beam diameter to a small beam diameter;

[0047] The second lens 3 is used to restore the light beam with a reduced diameter to parallel light;

[0048] The third lens 4 is used to guide the parallel light with a reduced diameter into the parallel optical path stage of the infinite imaging system 5, while ensuring that the coaxial light of the infinite imaging system can still pass through;

[0049] The infinite imaging system 5 is used to adjust the beam diameter again to match the diameter of the fiber core to be measured.

[0050] The laser used as a light source generally has a spot size ranging from a few millimeters to tens of millimeters. If it is to be coupled into a single core of a test optical fiber with a diameter in the micron range, beam shaping must be performed first. The reduction factor and degree need to be determined based on the specific core diameter of the test optical fiber and the parameters of the entire test system.

[0051] In this application, a beam adjustment device is used to perform the first diameter adjustment. Due to the limitations of the beam adjustment device itself, the adjusted spot diameter cannot match the diameter of the fiber core to be measured (about 5 microns in the embodiment). Therefore, an infinite imaging system is required to perform a secondary diameter adjustment to match the spot diameter with the diameter of the fiber core to be measured (1.5 microns in the corresponding embodiment).

[0052] In an infinity imaging system, the objective projects the specimen image at infinity, meaning that all light rays originating from a single point on the specimen emerge from the objective in a parallel fashion. Light rays at the center of the specimen (and the objective) are parallel to the optical axis. Light rays outside the specimen center are parallel to one another but not to the optical axis. In this system, light rays at the rear focal plane of the objective are parallel and can traverse a region known as "infinity space" without changing direction. "Coaxial light" refers to light rays emanating from the objective, which, after passing through the objective, propagate in a parallel fashion, as if they originated from a point source at infinity. This design allows light rays to remain parallel between the objective and the imaging lens, enabling the insertion of various optical elements such as filters, wave plates, and beamsplitters between the objective and the imaging lens without affecting image quality or requiring refocusing.

[0053] Preferably, the center of the incident light is coaxial with the first lens, the input end of the beam adjustment device is located on the focal plane of the first lens, and the output end is located on the focal plane of the second lens. In this case, the coupling efficiency can reach the highest.

[0054] The types of the first lens include but are not limited to: a single lens and a compound lens.

[0055] Types of the second lens include, but are not limited to, plano-convex lenses, aspheric lenses, and Fresnel lenses.

[0056] Preferably, the parameters satisfy the following conditions: ,in, is the focal length of the second lens, is the focal length of the objective lens in the infinite imaging system, is the diameter of the small beam after adjustment, is the core diameter of the fiber to be measured.

[0057] Preferably, the beam adjustment device is a special optical fiber device or an aperture.

[0058] Preferably, the special optical fiber device is a mode field adapter.

[0059] A mode field adapter (MFA) is a device used to connect optical fibers with different mode field diameters (MFDs) and numerical apertures (NAs). It maximizes the transmittance of the fundamental mode signal at the splice point. In practice, the MFA ratio varies depending on the specific fiber type and application requirements.

[0060] In beam shaping, a lens or focuser is used to focus the light beam onto an aperture. The position and aperture size of the aperture are adjusted to achieve the desired beam shape and performance. Specifically, by changing the aperture size of the aperture, the diameter of the beam passing through the aperture can be controlled, thereby affecting the size of the light spot.

[0061] Preferably, the first lens and the mode field adapter satisfy the following conditions: ,in, is the large mode field diameter of the mode field adapter, is the spot diameter of the incident beam, is the focal length of the first lens.

[0062] Preferably, the third lens is an optical lens. The optical lens is placed at the end of a special optical fiber device and can control the propagation path of the light beam to achieve a specific optical effect.

[0063] Preferably, the infinite imaging system is further used to visually couple the beam-shaped laser beam into a certain transmission pixel at the input end of the optical fiber to be measured.

[0064] On the basis of the above, the present application provides a device for testing the crosstalk rate of an image-transmitting optical fiber, the device comprising a laser, a beam shaping unit according to any embodiment of the present application, a light intensity detection unit, and a processing unit;

[0065] a laser, for emitting a parallel beam of light;

[0066] A beam shaping unit is used to adjust the spot diameter of the incident parallel light beam so that it does not exceed the diameter of a single pixel of the image transmission fiber to be measured, and couple the shaped parallel light beam into a pixel at the input end of the image transmission fiber to be measured, where the input end of the image transmission fiber to be measured is located on the focal plane of the infinite imaging system;

[0067] The light intensity detection unit is used to detect the luminous intensity of the stimulated transmission pixel and the adjacent transmission pixel;

[0068] The processing unit is used to calculate the sum of the light intensities of the stimulated transmitting pixel and the adjacent transmitting pixel, and calculate the ratio of the total light intensity of the adjacent transmitting pixel to the sum as the crosstalk rate.

[0069] The imaging fiber, as the device under test, consists of a pixel, outer cladding, and co-cladding. Thousands to tens of thousands of fiber cores are densely packed at the end face, each representing an independent pixel. These fibers are constructed by stacking thousands to tens of thousands of single-core capillary rods within a tube, or by closely packing thousands to tens of thousands of single-core optical fibers. The distance between cores does not exceed 10 microns, and the core diameter does not exceed 5 microns. The output end is directly connected to an imaging fiber crosstalk ratio tester, where a processing unit generates the intensity of the stimulated pixel, the intensity of adjacent pixel elements, and the crosstalk ratio.

[0070] In this application, the laser output light beam is coupled into only one fiber core (or pixel), illuminating that core and emitting light at the other end. However, due to crosstalk, some of the light propagates through this core into adjacent cores. As a result, at the crosstalk detection end, the excited core and its adjacent, affected cores all emit light, while the surrounding, unaffected cores remain dark.

[0071] Preferably, the laser emission spot is a circular spot.

[0072] Correspondingly, the present application provides a method for testing the crosstalk rate of an image transmission optical fiber, which is implemented by a crosstalk rate testing device according to any embodiment of the present application. The crosstalk rate testing method includes:

[0073] S1. Turn on the laser and emit a parallel beam to the beam shaping unit;

[0074] S2. Using an infinity imaging system, ensure that the shaped parallel beam is coupled into a pixel at the input end of the image transmission fiber to be measured.

[0075] S3. Obtain the luminous intensity of the stimulated transmission pixel and the adjacent transmission pixel;

[0076] S4. Calculate the sum of the light intensities of the stimulated transmitting pixel and the adjacent transmitting pixel, and calculate the ratio of the total light intensity of the adjacent transmitting pixel to the sum as the crosstalk rate.

[0077] Example

[0078] In this embodiment, the beam adjustment device is a special optical fiber device. Figure 2 As shown, the input end of the special optical fiber device includes an optical fiber core 21 and a cladding 22, and the output end includes an optical fiber core 23 and a cladding 24, and the ratio of the diameter of the optical fiber core 21 (large mode field diameter) to the diameter of the optical fiber core 23 (small mode field diameter) is preferably not more than 10, and is 5 in this embodiment.

[0079] like Figure 1 As shown, the infinity imaging system 5 is an infinity imaging microscope system, which includes: a CCD 51, a tube lens 52, a microscope imaging software 53 and a microscope objective lens 54. In the parallel light stage of the microscope, a parallel laser beam is introduced through an optical lens, and the laser is visually coupled into a core at the input end of the image transmission optical fiber.

[0080] like Figure 3 As shown, the image transmission optical fiber crosstalk rate testing device includes: a laser 6, a beam shaping unit (2, 3, 4, 5), a light intensity detection unit 7 and a processing unit 8;

[0081] a laser 6 for emitting a parallel light beam;

[0082] A beam shaping unit is used to adjust the spot diameter of the incident parallel light beam so that it does not exceed the diameter of a single pixel of the image transmission fiber 9 to be measured, and couple the shaped parallel light beam into a pixel at the input end of the image transmission fiber 9 to be measured, and the input end of the image transmission fiber 9 to be measured is located on the focal plane of the infinite imaging system 5;

[0083] The light intensity detection unit 7 is used to detect the luminous intensity of the stimulated transmission pixel and the adjacent transmission pixel;

[0084] The processing unit 8 is used to calculate the sum of the light intensities of the stimulated transmitting pixel and the adjacent transmitting pixel, and calculate the ratio of the total light intensity of the adjacent transmitting pixel to the sum as the crosstalk rate.

[0085] like Figure 4 As shown, the image transmission optical fiber 9 to be tested comprises image transmission elements 91, an outer cladding 92 and a common cladding 93. Thousands to tens of thousands of image transmission elements 91 are closely arranged on its end face.

[0086] The crosstalk rate test method provided in this application includes:

[0087] S1. Turn on the laser 6 so that it emits a parallel beam to the beam shaping unit;

[0088] S2 uses the infinity imaging system 5 to ensure that the shaped parallel beam is coupled into a pixel at the input end of the image transmission fiber 9 to be measured;

[0089] S3. Obtain the luminous intensity of the stimulated transmission pixel and the adjacent transmission pixel;

[0090] S4. Calculate the sum of the light intensities of the stimulated transmitting pixel and the adjacent transmitting pixel, and calculate the ratio of the total light intensity of the adjacent transmitting pixel to the sum as the crosstalk rate.

[0091] Figure 5 (a) is a schematic diagram of the microscope imaging end face before the test. Figure 5 (b) is a schematic diagram of the crosstalk phenomenon after the test. A comparison reveals that after coupling the laser into the transmitting pixel, the middle core becomes the stimulated transmitting pixel. Due to the crosstalk phenomenon, some optical signals also exist in the surrounding cores.

[0092] 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 specific characteristics, numbers, operations, constituent elements, components, or combinations 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.

[0093] In addition, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0094] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A beam shaping unit, characterized in that: The optical path includes: a first lens, a beam adjustment device, a second lens, a third lens and an infinite imaging system; The first lens is used to couple the incident light into the beam adjustment device; The beam adjusting device is used to adjust the beam diameter from a large beam diameter to a small beam diameter; The second lens is used to restore the light beam with a reduced diameter to parallel light; The third lens is used to introduce the parallel light with a reduced diameter into the parallel optical path stage of the infinite imaging system, while ensuring that the coaxial light of the infinite imaging system can still pass through; The infinite imaging system is used to adjust the beam diameter again to match the core diameter of the optical fiber to be measured.

2. The beam shaping unit according to claim 1, wherein: The center of the incident light is coaxial with the first lens. The input end of the beam adjustment device is located on the focal plane of the first lens, and the output end is located on the focal plane of the second lens.

3. The beam shaping unit according to claim 1, wherein: The parameters satisfy: ,in, is the focal length of the second lens, is the focal length of the objective lens in the infinite imaging system, is the diameter of the small beam after adjustment, is the core diameter of the fiber to be measured.

4. The beam shaping unit according to claim 1, wherein: The beam adjustment component is a special optical fiber component or an aperture.

5. The beam shaping unit according to claim 4, wherein: The special optical fiber device is a mode field adapter.

6. The beam shaping unit according to claim 5, wherein: The first lens and the mode field adapter meet the following requirements: ,in, is the large mode field diameter of the mode field adapter, is the spot diameter of the incident beam, is the focal length of the first lens.

7. The beam shaping unit according to claim 1, wherein: The infinite imaging system is also used to visually couple the beam-shaped laser beam into a certain transmission pixel at the input end of the optical fiber to be tested.

8. A device for testing the crosstalk rate of an image transmission optical fiber, characterized in that: include: A laser, a beam shaping unit, a light intensity detection unit, and a processing unit according to any one of claims 1 to 7; a laser, for emitting a parallel beam of light; A beam shaping unit is used to adjust the spot diameter of the incident parallel light beam so that it does not exceed the diameter of a single pixel of the image transmission fiber to be measured, and couple the shaped parallel light beam into a pixel at the input end of the image transmission fiber to be measured, where the input end of the image transmission fiber to be measured is located on the focal plane of the infinite imaging system; The light intensity detection unit is used to detect the luminous intensity of the stimulated transmission pixel and the adjacent transmission pixel; The processing unit is used to calculate the sum of the light intensities of the stimulated transmitting pixel and the adjacent transmitting pixel, and calculate the ratio of the total light intensity of the adjacent transmitting pixel to the sum as the crosstalk rate.

9. The crosstalk rate testing device according to claim 8, wherein: The laser emits a circular light spot.

10. A method for testing the crosstalk rate of an image transmission optical fiber, characterized in that: The crosstalk rate testing device according to claim 8 or 9 is used to implement the crosstalk rate testing method, comprising: S1. Turn on the laser and emit a parallel beam to the beam shaping unit; S2. Using an infinity imaging system, ensure that the shaped parallel beam is coupled into a pixel at the input end of the image transmission fiber to be measured. S3. Obtain the luminous intensity of the stimulated transmission pixel and the adjacent transmission pixel; S4. Calculate the sum of the light intensities of the stimulated transmitting pixel and the adjacent transmitting pixel, and calculate the ratio of the total light intensity of the adjacent transmitting pixel to the sum as the crosstalk rate.

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