A method for fiber optic end face inspection

Abstract

This invention primarily relates to the field of automated inspection, and particularly to a method for inspecting the end face of an optical fiber. The method involves acquiring an axially oriented image of the optical fiber end face; a plurality of point light sources uniformly distributed around the end face; the point light sources positioned in front of the end face along its axial direction; when the projection direction is the axial direction of the end face, and the plane containing the image of the end face is used as the projection plane, the projections of the point light sources lie on concentric circles of the projection of the center of the circle; each point light source generates a reflective area at its edge corresponding to one side of the end face, and this reflective area is imaged onto the image of the end face; the area information of the reflective areas formed by each point light source is acquired; and the overall tilt angle of the optical fiber end face is determined based on the ratio or difference of the area information of the reflective areas formed by each point light source.

Description

Technical Field

[0001] This invention mainly relates to the field of automated testing, and in particular to a method for testing the end face of optical fibers. Background Technology

[0002] Existing technology, such as patent application number 201410713984.8 entitled "Optical Fiber End-Face Inspection Method and Optical Fiber End-Face Polishing and Inspection Equipment," discloses "an optical fiber end-face polishing and inspection equipment, including a power supply device, a light source, a camera device, an image processing device, an image display device, a motor drive device, a discharge device, and an optical fiber clamping device. The power supply device is connected to the light source, camera device, image processing device, image display device, motor drive device, and discharge device respectively; the image processing device is connected to the camera device, image display device, motor drive device, and discharge device; the discharge device consists of an electrode group; the optical fiber clamping device is connected to the motor drive device; the optical fiber clamping device is provided with an optical fiber fixing slot, and the light source is opposite to the optical fiber fixing slot." This patent is a melting treatment device for optical fiber end faces. It melts the optical fiber end face using a discharge device and then images the optical fiber end face using a camera device. This patent defines some data that needs to be collected for end-face inspection, but it does not disclose a specific end-face inspection method.

[0003] For example, patent application number 201910430030.9, entitled "Fiber Optic End-Face Polishing Inspection Equipment and Method," discloses "a fiber optic end-face polishing inspection equipment that performs electro-thermal melting treatment on the cut end face of the fiber optic cable to ensure the consistency of cleanliness, damage, and end-face curvature radius of the fiber optic end face. After electro-thermal melting treatment, the equipment acquires images of the fiber optic end face in real time and transmits them to a display screen for observation. Simultaneously, it transmits these images to an image processing device for black-and-white binarization processing to calculate the cleanliness, damage, and curvature radius of the fiber optic end face. Based on the principle of optical reflection, the image processing device automatically determines the electro-thermal melting status of the fiber optic end face to determine whether an additional electro-thermal melting is needed to ensure that the deposits on the fiber optic end face are cleaned, the cut damage is repaired, and a suitable curvature radius is formed… The inspection steps include: acquiring images of the fiber optic end face; the image processing device processing the images acquired by the camera device…" The process involves: obtaining an image of the fiber end face after segmentation; a binarization process where the image of the fiber end face captured by the camera is transmitted to an image processing device for black-and-white binarization; a calculation and comparison process where the radius of curvature of the fiber end face is calculated and compared with a standard range parameter of the radius of curvature of the fiber end face preset in the image processing device. If the comparison result meets the predefined value, the operation ends; otherwise, an additional polishing step is added, and the steps of acquiring the fiber end face image and binarization are repeated, followed by recalculation and comparison, until the radius of curvature of the fiber end face is lower than the preset minimum value, at which point the operation ends. A radius of curvature meeting the predefined value means that the inner diameter of the formed bright ring is within the range between a circle with a preset radius R1 and a circle with a preset radius R2. This patent discloses the general process of detection when the melting processing device uses a ring light source, but it does not disclose the specific judgment method or the detection method when using a point light source, nor does it disclose the detection and judgment method for the fiber end face tilt angle.

[0004] Before optical fibers are processed by the aforementioned melting equipment, they need to be cut, which is usually done by a cleaver. For example, patent application number 202120851945.X, entitled "An Optical Fiber Cutter," discloses a "optical fiber cleaver body, including an optical cable fixing part, an optical fiber fixing platform, an inner cavity, a blade holder, and a slide rod; the optical cable fixing part is used to fix the stripped optical cable and arrange the optical fiber of the stripped cable on the optical fiber fixing platform; the bottom of the optical fiber fixing platform is provided with the inner cavity, the inner cavity is provided with the slide rod, and a spring is sleeved on the slide rod; the blade holder is provided with a cleaver, the blade holder is slidably disposed on the slide rod, and the blade holder is provided with an extension arm, which compresses the spring when the blade holder is close to one end of the slide rod and engages with the bayonet of the optical fiber cleaver body through a locking point of the extension arm." The cover is also equipped with a breaking device, which includes a breaking spring, an extension platform, and a breaking arm. During the closing process, the extension platform abuts against the surface of the blade holder and compresses the breaking spring, causing the extension platform and the breaking arm to retract. When the blade holder is pushed out by the compressed spring to the other end of the slide rod, the blade holder disengages from the extension platform, and the breaking arm extends to strike and break the optical fiber. An optical fiber cleaver is a commonly used tool. Its working principle is to cut a kerf in the optical fiber with a blade and then break the fiber by breaking it. However, this breaking method may cause the fiber end face to tilt. This tilt angle may still exist after melting, and existing melting equipment does not have a corresponding detection method when using a point light source. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for detecting the end face of an optical fiber, which is achieved through the following technical solution:

[0006] A method for inspecting the end face of an optical fiber, comprising an optical fiber having an end face with a center; the end face is a fused-face end face, and the edge of the end face has an arc-shaped transition towards the end face body.

[0007] Acquire an axially captured image of the fiber end face;

[0008] A plurality of point light sources are evenly distributed around the end face of the optical fiber; in the axial direction of the end face of the optical fiber, the plurality of point light sources are located in front of the end face of the optical fiber; when the projection direction is the axial direction of the end face of the optical fiber, and the plane where the image of the end face of the optical fiber is located is the projection plane, the projection of the plurality of point light sources is located on the concentric circles of the projection of the center of the circle.

[0009] The point light source can generate a reflective area on the edge of one side corresponding to the end face of the optical fiber, and the reflective area is imaged onto the end face of the optical fiber.

[0010] Obtain the area information of the reflective region formed by each of the point light sources;

[0011] The overall tilt angle of the fiber end face is judged to be qualified based on the ratio or difference of the area information of the reflective areas formed by each point light source.

[0012] Preferably, the point light sources are lit up sequentially, and the area information of the reflective area corresponding to each point light source is obtained.

[0013] Preferably, the maximum or minimum value of the area information of each reflective area corresponding to the point light source is selected, and the area information of the reflective areas formed by other point light sources is calculated using the maximum or minimum value as a reference value to obtain the ratio of the area of ​​each reflective area to the reference value. If the ratio of the area of ​​a reflective area to the reference value is greater than the set threshold, the fiber end face is determined to be unqualified.

[0014] Preferably, the maximum or minimum value of the area information of each reflective area corresponding to the point light source is selected, and the difference between the area information of the reflective areas formed by the other point light sources is calculated using the maximum or minimum value as a reference value. The difference area information of each reflective area relative to the reference value is obtained, and the ratio of the difference area information to the reference value is calculated. If the ratio of the difference area information to the reference value is greater than a set threshold, the fiber end face is determined to be unqualified.

[0015] Preferably, image information representing the brightness and darkness pixel values ​​of the fiber end face is obtained;

[0016] Edge detection is performed on the image to obtain the contour information of the fiber end face and the contour information of the reflective area located within the fiber end face;

[0017] The area information of each reflective region within the fiber endface is obtained using the maximum connected component algorithm.

[0018] Preferably, the point light sources are grouped into pairs, and on the projection plane, the two point light sources in a pair are located on opposite sides of the center of the circle and on the same straight line passing through the center of the circle.

[0019] The area information of the reflective area formed by the point light source is obtained, and the overall tilt angle of the fiber end face is judged to be qualified based on the ratio or difference between the two.

[0020] This invention also provides a method for detecting the end face of an optical fiber. The optical fiber has an end face with a center point. The end face is a fused-to-metal fiber end face, and its edge has an arc-shaped transition towards the main body of the end face.

[0021] Acquire an axially captured image of the fiber end face;

[0022] A plurality of point light sources are evenly distributed around the end face of the optical fiber; in the axial direction of the end face of the optical fiber, the plurality of point light sources are located in front of the end face of the optical fiber; when the projection direction is the axial direction of the end face of the optical fiber, and the plane where the image of the end face of the optical fiber is located is the projection plane, the projection of the plurality of point light sources is located on the concentric circles of the projection of the center of the circle.

[0023] The point light source can generate a reflective area on the edge of one side corresponding to the end face of the optical fiber, and the reflective area is imaged onto the end face of the optical fiber.

[0024] Within the projection plane, a virtual straight line formed by the projection of a point light source and the projection of the center of the circle is used as a dividing line to divide the reflective area formed on the fiber end face of the image into two parts.

[0025] Obtain the area information of the two segmented regions, and thus obtain the ratio or difference information of the areas of the two segmented regions;

[0026] The overall tilt angle of the fiber end face is determined based on the ratio or difference of the areas of the two regions corresponding to the point light source.

[0027] Preferably, if the ratio or difference between the areas of two segmented regions corresponding to the point light source is greater than a set threshold, the fiber end face is determined to be unqualified.

[0028] Preferably, the point light sources are lit up sequentially, and the area information of the reflective area corresponding to each point light source is obtained.

[0029] Preferably, the coordinates of the center of the circle on the projection plane are fixed coordinates, or the coordinates of the center of the fiber end face are obtained by obtaining the contour information of the fiber end face in the image and obtaining the aspect ratio information based on the contour information.

[0030] Preferably,

[0031] S1: Obtain image information representing the brightness and darkness pixel values ​​at the fiber end face;

[0032] S2: Perform edge detection on the image to obtain the outline information of the fiber end face and the outline information of the reflective area located in the fiber end face;

[0033] S3: Obtain the aspect ratio information based on the outline information of the fiber end face, and thus obtain the center coordinates of the fiber end face.

[0034] S4: Calculate the straight line information between the two based on the coordinate information of each point light source with a fixed relative position in the image and the coordinate information of the center of the circle;

[0035] S5: Flip the white pixels representing reflection located within the reflective area and on the straight line to black pixels, thus dividing the reflective area into two parts;

[0036] S6: Obtain the area information of the two segmented reflective regions using the maximum connected component algorithm.

[0037] This invention also provides a method for detecting the end face of an optical fiber, wherein the optical fiber has an end face with a center; the end face is a fused fiber end face, and the edge of the end face has an arc-shaped transition towards the end face body, characterized in that:

[0038] Acquire an axially captured image of the fiber end face;

[0039] A plurality of point light sources are evenly distributed around the end face of the optical fiber; in the axial direction of the end face of the optical fiber, the plurality of point light sources are located in front of the end face of the optical fiber; when the projection direction is the axial direction of the end face of the optical fiber, and the plane where the image of the end face of the optical fiber is located is the projection plane, the projection of the plurality of point light sources is located on the concentric circles of the projection of the center of the circle.

[0040] The point light source can generate a reflective area on the edge of one side corresponding to the end face of the optical fiber, and the reflective area is imaged onto the end face of the optical fiber.

[0041] Obtain the area information of the reflective region formed by each of the point light sources;

[0042] The symmetry of each reflective region is determined based on the area information of each reflective region corresponding to the point light source, thereby determining whether the overall tilt angle of the fiber end face is qualified.

[0043] This invention also provides a method for detecting the end face of an optical fiber, wherein the optical fiber has an end face with a center; the end face is a fused fiber end face, and the edge of the end face has an arc-shaped transition towards the end face body, characterized in that:

[0044] Acquire an axially captured image of the fiber end face;

[0045] A plurality of point light sources are evenly distributed around the end face of the optical fiber; in the axial direction of the end face of the optical fiber, the plurality of point light sources are located in front of the end face of the optical fiber; when the projection direction is the axial direction of the end face of the optical fiber, and the plane where the image of the end face of the optical fiber is located is the projection plane, the projection of the plurality of point light sources is located on the concentric circles of the projection of the center of the circle.

[0046] The point light source can generate a reflective area on the edge of one side corresponding to the end face of the optical fiber, and the reflective area is imaged onto the end face of the optical fiber.

[0047] Within the projection plane, a virtual straight line formed by the projection of a point light source and the projection of the center of the circle is used as a dividing line to divide the reflective area formed on the fiber end face of the image into two parts.

[0048] The symmetry of the reflective area is determined by the area information of the two divided regions, thereby determining whether the overall tilt angle of the fiber end face is qualified.

[0049] The beneficial effects of the present invention are as follows: The fiber end face detection method provided by the present invention can be applied to fusion splicing equipment. By illuminating the fiber end face with several point light sources, an image of crescent-shaped reflections is obtained. The area of ​​each crescent-shaped reflection is calculated, and the symmetry of each reflection is determined based on the area information, thereby determining whether the tilt angle of the fiber end face is qualified. Attached Figure Description

[0050] Figure 1 A schematic diagram showing the relative positions of the optical fiber, point light source, and camera is provided.

[0051] Figure 2 A schematic diagram of the structure when the fiber end face has an angle is shown;

[0052] Figure 3 This shows a schematic diagram of an image when a point light source is lit.

[0053] Figure 4 This diagram shows a line image of an optical fiber end face with an angle and four point light sources lit up.

[0054] Figure 5 This shows a schematic diagram of a line image when a point light source is lit. Detailed Implementation

[0055] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0056] The equipment used in this method is such as Figure 1As shown, optical fiber 1 has an end face with a center. The end face is a fiber end face treated with existing fusion processing technology. The edge of the end face has an arc-shaped transition towards the main body of the end face. The fusion processing eliminates impurities such as burrs and dust particles caused by fiber optic cutting. Figure 2 As shown, if the fiber end face is tilted, this tilt angle may not disappear after melting. Figure 2 The image shows a side view of the optical fiber 1 with an angle, while the camera 3 used in this patent is facing the end face of the optical fiber and is capturing the forward end face of the optical fiber. Therefore, it cannot directly capture whether the end face of the optical fiber is tilted.

[0057] During fiber optic end-face inspection, several point light sources emit light simultaneously or sequentially, allowing camera 3 to acquire an image of the fiber optic end-face when these point light sources are emitting light. The simultaneous or sequential emission of light from each point light source depends on the number of point light sources. If there are too many point light sources, the resulting reflective areas may interconnect and interfere with each other, requiring sequential emission of light from each point light source. This image can be displayed on a fusion splicing device. The pixels on the image may differ from the pixels to be calculated in this method; the pixels displayed may be compressed for display purposes. The processor and memory of the fusion splicing device process the image, copying the pixel data acquired by the camera to an designated computational area and binarizing the grayscale values ​​of the pixels. Grayscale values ​​exceeding a set threshold are considered bright spots, while those below the set threshold are considered black spots, thus forming a black-and-white image of the fiber optic end-face. Edge detection provides the image's contour information, thus obtaining the area information of the fiber optic end-face. The maximum connected component algorithm provides the area information of the reflective areas. When calculating information about reflective areas, some noise points caused by equipment noise, error interference, or external environment are removed. For example, areas with fewer than a specified number of pixels can be defined as noise points and are not included in the reflective area information.

[0058] In the axial direction of the optical fiber or its end face, several point light sources 2 are located in front of the optical fiber end face. In the projection along the axial direction, the several point light sources 2 are located on concentric circles around the center of the optical fiber, and the point light sources 2 are uniformly distributed around the optical fiber end face.

[0059] The fiber optic end face is placed in a closed, dark space. The point light source 2 illuminates the fiber optic end face. Here, the point light source's function is to generate reflection at the curved edge of the fiber optic end face, rather than illuminating the entire end face. For example... Figure 3As shown, since it is a point light source and the fiber optic end face is a circular cross-section, the camera 3 located on the front of the fiber optic end face can only receive the reflection generated by the curved part of the fiber optic end face, which is a crescent-shaped reflection area. The reflection generated on the end face of the fiber optic end face, which is roughly parallel to the CCD plane of the camera 3, will not be received by the camera 3. The illumination of the background far from the fiber optic end face by the point light source 2 will form a white background in the image. In addition to the crescent-shaped reflection, the remaining part of the end face will form a dark fiber optic end face image.

[0060] Theoretically, two or more point light sources are sufficient, but in practical applications, four point light sources are generally used. Although the term "point light source" is used in this patent, it can also refer to parallel light sources facing the fiber end face. Furthermore, the fiber end face is the end face after end-fusion treatment. Even with the same equipment and the same qualified, tilt-free end face, the size of the arc at the edge of the fiber end face may differ due to external environment, discharge power, and other factors. Therefore, the overall size of the crescent-shaped reflection formed after each fusion may also differ (the reflections of the same fiber are the same, but the reflections of different fibers after fusion are different in size from the reflections of the previous fiber). However, the symmetry of each reflection, including its area, is basically the same.

[0061] When the projection direction is along the axis of the fiber optic end face, and the plane containing the image of the fiber optic end face is taken as the projection plane, the projections of several point light sources lie on concentric circles of the projection center. If the image formed by camera 3 is considered as a projection plane, although this projection plane is a virtual image, if the imaging area of ​​camera 3 is large enough, it can still observe the relative positions of the point light sources, and these relative positions are fixed. When a point light source emits light, it can generate a reflective area at the edge of the fiber optic end face. This reflective area is imaged onto the image of the fiber optic end face. Theoretically, if the imaging area is large enough, the position of the point light source can also appear on the image. Therefore, the image of the fiber optic end face can also be understood as the aforementioned projected image. The description method of "projection plane" is used in this patent mainly because the image captured by the camera is mainly an image of the fiber optic end face. Generally speaking, point light sources do not appear in the real image. Placing the image and point light sources on the same plane facilitates description and subsequent calculations. Therefore, the description method of "projection plane" is adopted.

[0062] Example 1:

[0063] If the reflective areas formed by the simultaneous illumination of each point light source 2 are not connected to each other, the image information can be directly obtained and the area of ​​each reflective area in the fiber end face can be calculated. If the simultaneous illumination of each point light source 2 will affect the reflective image between the point light sources 2, the point light sources 2 can be illuminated sequentially to obtain the area of ​​the reflective area in the fiber end face after each point light source 2 is illuminated individually.

[0064] The method of judgment is to select the maximum or minimum value of the area information of each reflective area corresponding to the point light source, and use the maximum or minimum value as the benchmark to calculate the ratio of the area information of the reflective areas formed by other point light sources to obtain the ratio of the area of ​​each reflective area to the benchmark value. If the ratio of the area of ​​several reflective areas to the benchmark value is greater than the set threshold, the fiber end face is judged to be unqualified.

[0065] This patent mainly uses four point light sources as an example for illustration.

[0066] When determining whether the tilt angle of the fiber optic end face is acceptable:

[0067] For example, such as Figure 4 As shown, the areas of the four reflective regions obtained after testing are 8.90, 6.12, 7.83, and 9.26, respectively. The minimum value of 6.12 is selected as the baseline value and used to calculate the ratios of each area (with the minimum value as the denominator). The calculated results are 1.45, 1, 1.28, and 1.51, respectively. Theoretically, if the fiber end face is a plane, all four ratios would be approximately 1. However, the maximum allowable tilt angle threshold for the fiber end face is 1.20. If any one of the data exceeds this threshold, the fiber end face is considered to have an excessive tilt angle, and therefore, the fiber end face is deemed unqualified.

[0068] The area data mentioned above is a virtual value, not the actual value of the reflective area. It is mainly calculated and compressed based on the number of pixels on the fiber end face, and is a virtual numerical representation of the area. The threshold for the maximum allowable tilt angle can be obtained based on actual experimental data. Although the area data mentioned above is a virtual value, when the maximum or minimum value is used as a benchmark and compared with other areas, it can still reflect the degree of difference between the areas of various reflective regions in the image, thereby determining whether the reflective regions are symmetrical, and thus judging whether the tilt angle of the fiber end face is qualified. Other data in this patent are consistent with this embodiment, and the corresponding data will not be described in detail.

[0069] Since the slope of the fiber optic end face must be higher at one end and lower at the other, several point light sources can be grouped into pairs. On the projection plane, a pair of point light sources is located on both sides of the center of a circle and on the same straight line passing through the center. The difference or ratio of the two direct data points in a pair is calculated. If the ratio or difference of one pair does not meet the set threshold, the fiber optic end face can be directly determined to be unqualified.

[0070] For example, if the data above is based on actual values, the minimum value of 6.12 and the maximum value of 9.26 must be the highest and lowest points, respectively. The ratio between the two is 1.51, which is much greater than the threshold of 1.20. Therefore, the fiber end face is judged to be unqualified.

[0071] Alternatively, when determining whether the tilt angle of the fiber end face is acceptable:

[0072] The maximum or minimum area information of each reflective area corresponding to a point light source is selected, and the difference between the area information of the reflective areas formed by the other point light sources is calculated using the maximum or minimum value as a reference value. The difference area information of each reflective area relative to the reference value is obtained. The ratio of the difference area information to the reference value is calculated. If the ratio of several of the difference area information to the reference value is greater than a set threshold, the fiber end face is determined to be unqualified.

[0073] The general process of data acquisition in the above technical solution within the program is as follows:

[0074] Image information of the fiber end face is obtained through binarization processing;

[0075] Edge detection is performed on the image to obtain the contour information of the fiber end face and the contour information of the reflective area located within the fiber end face;

[0076] The area information of each reflective region within the fiber endface is obtained using the maximum connected component algorithm.

[0077] The present invention also provides another embodiment, specifically:

[0078] Example 2:

[0079] Optical fiber has an end facet, which has a center. The end facet is a fused-to-metal structure, and its edges have an arc-shaped transition towards the main body of the end facet.

[0080] Acquire an axially oriented image of the fiber end face.

[0081] Several point light sources are uniformly distributed around the end face of an optical fiber. Along the axial direction of the end face, these point light sources are located in front of it. When the projection direction is the axial direction of the end face, and the plane containing the image of the end face is the projection plane, the projections of the point light sources lie on concentric circles of the projection of the center of the optical fiber.

[0082] The point light source can generate a reflective area on the edge of the side corresponding to the end face of the optical fiber, and this reflective area is imaged onto the end face of the optical fiber.

[0083] Within the projection plane, a virtual straight line formed by the projection of a point light source and the projection of the center of the circle is used as a dividing line to divide the reflective area formed on the fiber end face of the image into two parts.

[0084] By obtaining the area information of the two segmented regions, the ratio or difference between the areas of the two segmented regions can be obtained.

[0085] The overall tilt angle of the fiber optic end face is determined based on the ratio or difference of the areas of two regions corresponding to several point light sources. In this embodiment, the symmetry of each reflective region is determined based on the area information of each reflective region corresponding to a point light source, thereby determining whether the overall tilt angle of the fiber optic end face is acceptable.

[0086] The difference between Example 2 and Example 1 is that Example 1 requires detecting the area information of each crescent-shaped reflective region before making a judgment, while Example 2 judges based on the two parts divided by the straight line passing through the corresponding point light source and the center of the circle for each crescent-shaped reflective region. When the fiber end face has a slope, the crescent-shaped reflective regions formed by the point light source illumination may have different areas, and their positions will also shift relative to the fiber end face without tilt angle. If the straight line between the point light source and the center of the circle is used as a reference line, the center line of the symmetrical crescent-shaped reflective regions generated by the corresponding point light source will be offset above or below this straight line, thus the crescent-shaped reflective regions are offset above or below the straight line between the point light source and the center of the circle. When a point light source forms a corresponding reflective region, such as Figure 5 As shown, the ratio of the areas of the two parts a and b after the reflective area is divided by the point light source and the center of the circle can be used to determine whether the fiber end face is qualified.

[0087] If the ratio or difference of the areas of two segmented regions corresponding to a point light source is greater than a set threshold, then the fiber end face is determined to be the fiber end face.

[0088] Once a reflective area is segmented, the number of pixels in each segment is counted and directly compared. For example, the corresponding ratios for four reflective areas are 1.15, 1.37, 1.08, and 1.42. If the maximum allowable tilt angle threshold for the fiber endface is 1.20, then if a tilt angle of 1.37 is detected, the fiber endface is considered unqualified, and no further testing is required.

[0089] In Example 2, the center coordinates of the circle in the image or projection plane can be considered as fixed coordinates, or the position of the center coordinates can be obtained through real-time detection.

[0090] Since the position of camera 3 on the device is fixed, the coordinates of the position of each point light source in the image captured by camera 3 are also known and fixed. In general, since the optical fiber is fixed inside the device, the coordinates of the center of the optical fiber end face in the image can also be fixed and known.

[0091] If the center of the circle is taken as a fixed point, since the positions of the center of the circle and each point light source are known and fixed (the position of the point light source on the projection plane), the line connecting the center of the circle and each point light source can be taken as the black area point in advance for each imaging, and the ratio of the area of ​​the segmented reflective area can be directly calculated.

[0092] Of course, to reduce the deviation, the coordinates of the center point can also be the coordinates of the center of the circle located on the fiber end face within the image, calculated by the system. After obtaining the center coordinates, since the position of the point light source is known and fixed, the line connecting the two can be turned black, and then the ratio of the areas of the segmented reflective regions can be calculated.

[0093] If the center coordinates are used as real-time dynamic coordinates, the general process of data acquisition in the above technical solution within the program is as follows:

[0094] S1: Image information of black and white pixel values ​​of the fiber end face is obtained through binarization processing;

[0095] S2: Perform edge detection on the image to obtain the outline information of the fiber end face and the outline information of the reflective area located in the fiber end face;

[0096] S3: Obtain the aspect ratio information based on the outline information of the fiber end face, and thus obtain the center coordinates of the fiber end face.

[0097] S4: Calculate the straight line information between the two based on the coordinate information of each point light source with a fixed relative position in the image and the coordinate information of the center of the circle;

[0098] S5: Flip the white value pixels representing reflection located on the straight line within the reflective area to black value pixels, thus dividing the reflective area into two parts;

[0099] S6: Obtain the area information of the two segmented reflective regions using the maximum connected component algorithm.

[0100] In this embodiment, the symmetry of the reflective area is determined based on the area information of the two regions after the crescent-shaped reflective segmentation, thereby determining whether the overall tilt angle of the fiber end face is qualified.

Claims

1. A method for detecting the end face of an optical fiber, comprising an optical fiber having an end face with a center; the end face being a fused end face, and the edge of the end face having an arc-shaped transition towards the end face body, characterized in that: Acquire an axially captured image of the fiber end face; A plurality of point light sources are evenly distributed around the end face of the optical fiber; in the axial direction of the end face of the optical fiber, the plurality of point light sources are located in front of the end face of the optical fiber; when the projection direction is the axial direction of the end face of the optical fiber, and the plane where the image of the end face of the optical fiber is located is the projection plane, the projection of the plurality of point light sources is located on the concentric circles of the projection of the center of the circle. The point light source can generate a reflective area on the edge of one side corresponding to the end face of the optical fiber, and the reflective area is imaged onto the end face of the optical fiber. Obtain the area information of the reflective region formed by each of the point light sources; The overall tilt angle of the fiber end face is judged to be qualified based on the ratio or difference of the area information of the reflective areas formed by each point light source.

2. The fiber optic end-face detection method according to claim 1, characterized in that: The point light sources are lit up sequentially, and the area information of the reflective area corresponding to each point light source is obtained.

3. The fiber optic end-face detection method according to claim 1, characterized in that: The maximum or minimum value of the area information of each reflective area corresponding to the point light source is selected, and the area information of the reflective areas formed by the other point light sources is calculated using the maximum or minimum value as a reference value. The ratio of the area of ​​each reflective area to the reference value is obtained. If the ratio of the area of ​​a reflective area to the reference value is greater than the set threshold, the fiber end face is determined to be unqualified.

4. The fiber optic end-face detection method according to claim 1, characterized in that: The maximum or minimum value of the area information of each reflective area corresponding to the point light source is selected, and the difference between the area information of the reflective areas formed by the other point light sources is calculated using the maximum or minimum value as the reference value. The difference area information of each reflective area relative to the reference value is obtained. The ratio of the difference area information to the reference value is calculated. If the ratio of the difference area information to the reference value is greater than the set threshold, the fiber end face is determined to be unqualified.

5. The fiber optic end-face inspection method according to any one of claims 1 to 4, characterized in that: Obtain image information representing the brightness and darkness pixel values ​​at the fiber end face; Edge detection is performed on the image to obtain the contour information of the fiber end face and the contour information of the reflective area located within the fiber end face; The area information of each reflective region within the fiber endface is obtained using the maximum connected component algorithm.

6. The fiber optic end-face inspection method according to any one of claims 1 to 4, characterized in that: The point light sources are grouped into two groups. On the projection plane, the two point light sources in a group are located on opposite sides of the center of the circle and on the same straight line passing through the center of the circle. The area information of the reflective area formed by the point light source is obtained, and the overall tilt angle of the fiber end face is judged to be qualified based on the ratio or difference between the two.

7. A method for detecting the end face of an optical fiber, the optical fiber having an end face with a center; the end face being a fused end face, the edge of the end face having an arc-shaped transition towards the end face body, characterized in that: Acquire an axially captured image of the fiber end face; A plurality of point light sources are evenly distributed around the end face of the optical fiber; in the axial direction of the end face of the optical fiber, the plurality of point light sources are located in front of the end face of the optical fiber; when the projection direction is the axial direction of the end face of the optical fiber, and the plane where the image of the end face of the optical fiber is located is the projection plane, the projection of the plurality of point light sources is located on the concentric circles of the projection of the center of the circle. The point light source can generate a reflective area on the edge of one side corresponding to the end face of the optical fiber, and the reflective area is imaged onto the end face of the optical fiber. Within the projection plane, a virtual straight line formed by the projection of a point light source and the projection of the center of the circle is used as a dividing line to divide the reflective area formed on the fiber end face of the image into two parts. Obtain the area information of the two segmented regions, and thus obtain the ratio or difference information of the areas of the two segmented regions; The overall tilt angle of the fiber end face is determined based on the ratio or difference of the areas of the two regions corresponding to the point light source.

8. The fiber optic end-face inspection method according to claim 7, characterized in that: If the ratio or difference between the areas of two segmented regions corresponding to the point light source is greater than a set threshold, the fiber end face is determined to be unqualified.

9. The fiber optic end-face inspection method according to claim 7, characterized in that: The point light sources are lit up sequentially, and the area information of the reflective area corresponding to each point light source is obtained.

10. The fiber optic end-face detection method according to claim 7, characterized in that: The coordinates of the center of the circle on the projection plane are fixed coordinates, or the coordinates of the center of the fiber end face can be obtained by obtaining the contour information of the fiber end face in the image and obtaining the aspect ratio information based on the contour information.

11. The fiber optic end-face inspection method according to any one of claims 7 to 10, characterized in that: S1: Obtain image information representing the brightness and darkness pixel values ​​at the fiber end face; S2: Perform edge detection on the image to obtain the outline information of the fiber end face and the outline information of the reflective area located in the fiber end face; S3: Obtain the aspect ratio information based on the outline information of the fiber end face, and thus obtain the center coordinates of the fiber end face. S4: Calculate the straight line information between the two based on the coordinate information of each point light source with a fixed relative position in the image and the coordinate information of the center of the circle; S5: Invert the white value pixels representing reflections located on the straight line within the reflective area to black value pixels, thus dividing the reflective area into two parts; S6: Obtain the area information of the two segmented reflective regions using the maximum connected component algorithm.

12. A method for detecting the end face of an optical fiber, the optical fiber having an end face with a center; the end face being a fused end face, the edge of the end face having an arc-shaped transition towards the end face body, characterized in that: Acquire an axially captured image of the fiber end face; A plurality of point light sources are evenly distributed around the end face of the optical fiber; in the axial direction of the end face of the optical fiber, the plurality of point light sources are located in front of the end face of the optical fiber; when the projection direction is the axial direction of the end face of the optical fiber, and the plane where the image of the end face of the optical fiber is located is the projection plane, the projection of the plurality of point light sources is located on the concentric circles of the projection of the center of the circle. The point light source can generate a reflective area on the edge of one side corresponding to the end face of the optical fiber, and the reflective area is imaged onto the end face of the optical fiber. Obtain the area information of the reflective region formed by each of the point light sources; The symmetry of each reflective region is determined based on the area information of each reflective region corresponding to the point light source, thereby determining whether the overall tilt angle of the fiber end face is qualified.

13. A method for detecting the end face of an optical fiber, the optical fiber having an end face with a center; the end face being a fused-to-metal fiber end face, the edge of the end face having an arc-shaped transition towards the end face body, characterized in that: Acquire an axially captured image of the fiber end face; A plurality of point light sources are evenly distributed around the end face of the optical fiber; in the axial direction of the end face of the optical fiber, the plurality of point light sources are located in front of the end face of the optical fiber; when the projection direction is the axial direction of the end face of the optical fiber, and the plane where the image of the end face of the optical fiber is located is the projection plane, the projection of the plurality of point light sources is located on the concentric circles of the projection of the center of the circle. The point light source can generate a reflective area on the edge of one side corresponding to the end face of the optical fiber, and the reflective area is imaged onto the end face of the optical fiber. Within the projection plane, a virtual straight line formed by the projection of a point light source and the projection of the center of the circle is used as a dividing line to divide the reflective area formed on the fiber end face of the image into two parts. The symmetry of the reflective area is determined by the area information of the two divided regions, thereby determining whether the overall tilt angle of the fiber end face is qualified.

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