CN104019757B - A kind of fiber array fibre core is away from precision measurement method and system - Google Patents

Abstract

The present invention provides a method and system for precise measurement of fiber-optic array core distance, wherein the method includes: using a preset calibration template to calibrate to obtain an error; using the preset measurement template to collect the end face of the measured optical fiber array Image, the measurement template and the end face of the measured optical fiber array are correspondingly fixed on a movable workbench, and there is a light source light in the optical fiber of the optical fiber array; according to the measurement template, according to the preset algorithm, the The multiple images collected are sequentially spliced and restored, and processed to obtain a processed image, and the position of the fiber core is calculated according to the processed image and the error. The invention can effectively improve the measurement accuracy of the fiber-core distance of the optical fiber array without increasing the cost.

Description

A method and system for precise measurement of the core distance of an optical fiber array

technical field

The invention relates to the field of measurement technology, in particular to a method and system for precise measurement of the core distance of an optical fiber array.

Background technique

Optical fiber array is the most widely used device for connecting optical devices and optical fibers in optical fiber communication systems. It is mainly used in planar optical waveguide devices, LD/PD array optical fiber devices, arrayed waveguide grating optical communication networks, dense wavelength division multiplexing and multi-channel In the micro-optical module, it has the characteristics of flexible image transmission, large degree of freedom in the use of space, easy realization of slender structure, and light weight. The fiber array has three types of fiber core distances: 125μm, 127μm, and 250μm, and the number of channels is 1, 2, 4, 8, 16, 32, 64, etc., and the number of channels can reach up to 128. Due to manufacturing and assembly errors, the arrangement of optical fibers in the V-groove is not strictly equidistant. For the accurate connection between the fiber array and optical components in various fields, the core position error of the fiber array is the key factor causing the coupling loss. Therefore, in order to realize the precise connection between the fiber array and optical components, minimize the coupling loss, and improve the alignment accuracy during the coupling process, it is very necessary to precisely detect the position of the fiber core of the fiber array.

At present, there are roughly the following methods and systems for measuring the position of the fiber core of an optical fiber array.

One measurement method is manual measurement, that is to say, manually observe the microscope, move the workbench holding the fiber array to align the fiber core with the center of the target, and then read the distance between the fiber cores through the feedback data of the grating scale on the workbench. actual relative value. However, this measurement method is inefficient, and the measurement results are seriously affected by humans. In order to meet the needs of mass production, reduce costs and improve production efficiency, it is necessary to develop a non-contact, high-precision automated fiber array spacing measurement equipment.

The measurement accuracy of several other measurement methods is relatively high. One is the relative measurement method. The specific process is that the standard optical fiber array fixed on the piezoelectric regulator performs high-speed rotational movement, overlaps and couples with the core of the sample array to be measured, and measures The optical fiber coupling parameters generated by the rotational motion are obtained, so as to obtain the offset distance and offset direction of the fiber array core. The other is that the center of the FA can be observed by the near-field mode (NFP) optical profiler through the white light source transmitted to the fiber array (FA), and the NFP optical profiler will find the collection center of the center coordinates of each fiber through the monitoring process . These methods have high measurement accuracy and short time consumption, but they all have a common disadvantage, that is, the measurement equipment is very expensive. For many scientific research units, institutions, colleges and some enterprises, it is necessary to purchase a set of measurement equipment for related Research is a very difficult thing.

Another method is to use an accurate fiber array template as a reference, obtain the fiber core coordinates of the fiber array and the apex coordinates of the V-groove through image recognition and processing, and obtain the fiber core position distribution map of the fiber array and Vertex distribution map of a V-groove. This method does not require a sub-micron-level high-precision linear transmission platform. Relatively speaking, the measurement system is more compact and the price is relatively low. However, since the method does not calibrate the measurement system, and the measurement method does not In the step of splicing and restoration of images, the measurement template does indeed assist in the relevant settings of splicing, so its measurement accuracy is low.

To sum up, in the existing measurement methods and systems, some measurement techniques have low precision, while high-precision measurement techniques are complex and expensive. Therefore, there is an urgent need to develop a simplified, economical, and high-precision method and system for measuring the core position of an optical fiber array.

Contents of the invention

In view of this, the present invention provides a method for precise measurement of the core distance of an optical fiber array, the method comprising:

Step A, use the preset calibration template to calibrate, so as to obtain the systematic error;

Step B, collect the image of the end face of the tested optical fiber array through a preset measurement template, the measurement template is fixed on a movable workbench corresponding to the end face of the tested optical fiber array, and the optical fibers of the optical fiber array have The light from the light source is conducting, the image collected for the first time includes at least two fiber cores, the worktable is moved, and then the image of the end face of the optical fiber array under test is collected, and the image collected again includes at least two fiber cores, and at least one of the fiber cores is the upper For one of the fiber cores in the image collected at one time, continue to move the worktable in the same direction, and repeat the process of collecting images until the end face of the entire measured optical fiber array is collected;

Step C, according to the measurement template, according to the preset algorithm, sequentially splicing and restoring the collected multiple images, and processing them to obtain the processed image, according to the processed image and the system Error, calculate the core position. .

The present invention also provides a precision measurement system for the fiber-optic array core distance, the system comprising:

The calibration template is used to calibrate the error of the microscopic amplification module in the system;

The measurement template is used to be placed at a position corresponding to the end face of the optical fiber array to be tested;

The workbench is used to fix the fiber array under test and drive the fiber array under test to move;

The image acquisition module is used to collect the end face image of the measured optical fiber array superimposed with the measurement template through the light source, the image collected for the first time includes at least two fiber cores, and after moving the workbench, collect the end face of the measured optical fiber array again Image, the image collected again includes at least two fiber cores, and at least one fiber core is one of the fiber cores in the image collected last time, after continuing to move the workbench in the same direction, repeat the process of image collection , until the end face of the entire measured optical fiber array is collected;

The image processing module is used for splicing and restoring the multiple collected images according to the preset algorithm according to the measurement template, and processing them to calculate the position of the fiber core.

The technical solution provided by the invention can effectively reduce the measurement cost of the fiber-core distance of the optical fiber array, and can also ensure its high measurement accuracy.

Description of drawings

Fig. 1 is a flow chart of a precise measurement method for the core distance of an optical fiber array provided by the present invention.

Fig. 2 is a schematic structural diagram of a calibration template provided by the present invention.

Fig. 3 is a flow chart of calibrating an image acquisition device by using a calibration template provided by the present invention.

Fig. 4 is a schematic structural diagram of a measurement template provided by the present invention.

FIG. 5A is a schematic diagram of a situation where the positions of the two front and back images deviate, provided by the present invention.

FIG. 5B is a schematic diagram of a situation where there is no deviation in the positions of the front and rear images provided by the present invention.

Fig. 6 is a schematic structural diagram of another measurement template provided by the present invention.

Fig. 7 is a schematic diagram of a precision measuring device for the core distance of an optical fiber array provided by the present invention.

FIG. 8A is a schematic diagram of a position error of two images provided by the present invention.

Fig. 8B is a schematic diagram of correct positions of two images provided by the present invention.

Fig. 9 is a schematic structural diagram of a measurement template provided in the prior art.

Fig. 10 is a flow chart of an image processing algorithm for calculating the fiber-core distance provided by the present invention.

Fig. 11 is a microscopic enlarged image of a treated optical fiber array end face provided by the present invention.

Fig. 12 is a schematic diagram of a precision measurement system for the core distance of an optical fiber array provided by the present invention.

detailed description

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Method example:

Please refer to FIG. 1 , which shows the flow of an embodiment of the method for measuring the distance between the cores of an optical fiber array according to the present invention. This embodiment may include the following steps.

Step 101, use a preset calibration template to perform calibration, so as to obtain an error.

The calibration module is a special template for calibration. The reason for using the calibration template is to start with the calibration.

Calibration generally refers to testing the accuracy (precision) of the instrument used, so as to determine the input-output relationship of the instrument or measurement system, and to assign the scale value of the instrument or measurement system; to determine the static characteristic index of the instrument or measurement system; to eliminate Systematic error, improving the accuracy of an instrument or system. Therefore, in scientific measurement, calibration is an important step that cannot be ignored. Since the technical solution provided by the present invention needs to amplify the end face of the measured optical fiber array, and then collect the amplified image, before the measurement, it is necessary to calibrate the microscopic amplification device, and the calibration template is specially made for calibration. A device, as shown in Figure 2.

Please refer to Figure 3, the process of using the calibration template to calibrate may include the following steps:

Step 201, placing the calibration template in front of the image acquisition device.

Usually, the calibration template will be placed in front of the image acquisition device, so that the geometric figures on the calibration template can be clearly displayed on the captured image.

Step 202, collecting images of the calibration template.

In order to obtain the relevant error parameters of the measurement system, the image of the calibration template needs to be collected, and the error parameters are determined by the difference between the geometric figures on the collected image and the actual calibration dots. The specific process of determining the error parameters is in In the next steps, it will be further explained.

Step 203, detecting geometric figures in the image.

After the image of the calibration template is collected, the collected image needs to be further analyzed and tested to obtain the size and position information of each geometric image in the image. The process of obtaining the relevant information of the calibration dots will be described in detail in the subsequent steps.

Step 204, calculating the relevant parameters of the microscopic magnifying device.

According to the information obtained in step 203, the relevant parameters are calculated. For example, the geometric image on the calibration template is a calibration dot, and the actual diameter and spacing of the calibration dots are known, then a certain The diameter Φ1 of the calibration point is compared with the actual diameter Φ2 of the calibration point, that is, Φ1/Φ2, so as to calculate the magnification. Similarly, parameters such as system error and aberration can be calculated based on other information.

In the prior art, there is usually no dedicated calibration template for optical fiber array measurement, so its measurement accuracy is often not ideal. However, the present invention provides a calibration template specially for the technical solution of measuring the fiber core position of the optical fiber array, which can effectively improve the measurement accuracy.

Step 102, collect the end face image of the tested optical fiber array through the preset measurement template, the image collected for the first time includes at least two fiber cores, move the worktable, and then collect the end face image of the tested optical fiber array, and the image collected again Including at least two fiber cores, and at least one fiber core is one of the fiber cores in the image collected last time, continue to move the worktable in the same direction, and repeat the process of collecting images until the entire end face of the fiber array under test has been collected.

The measurement template in this step and the calibration template in step 101 are two different templates: the measurement template is used during actual measurement of the optical fiber array under test; the calibration template is used during calibration. Although the purposes of the two are different, their production materials and processes are basically the same. The template is usually made of a material that is relatively transparent, small in thickness, good in strength, and low in thermal expansion coefficient, such as optical glass, and then the material is passed through micro-nano The photolithography process is processed to make the required template, and its structure is shown in Figure 4. It can be seen from Fig. 4 that the measurement template usually includes image coding information, and the image coding information can be set as the measurement template shown in Fig. There are short lines, the so-called main line and short lines are the image coding information, of course, the image coding information is not limited to the main line and short lines, and can also be set as other geometric figures that can be used for image coding. Before explaining the reasons for setting the main line and the short line on the measurement template, the technical difficulties of measuring the fiber core of the fiber array should be explained first.

Since the measurement of the core of the fiber array is a high-precision measurement, the measurement is basically at the nanometer level. The core diameter of an optical fiber is usually only tens of microns at most. If you want to measure the core of the fiber array more accurately, High-precision measuring equipment must be used. When performing this type of measurement, it is one of the essential steps to amplify the end-face image of the optical fiber array measurement. Due to the limited field of view of the equipment for microscopic amplification, when performing high-precision measurement, the measured optical fiber array The fiber core will be magnified many times. In this way, only 1 or 2 fiber cores can be included in the field of view, and a measured end face usually includes multiple fiber cores. If you want to know the position of each fiber core, Then it is necessary to obtain the position information of all the fiber cores on the entire tested end face. This is also one of the technical difficulties that must be solved in the measurement of the fiber core position of the fiber array. Therefore, in the prior art, the position information of only one fiber core is usually obtained at a time, and then the information obtained multiple times is comprehensively processed to finally obtain the desired result. Therefore, in the actual application process, in order to obtain the position information of all fiber cores, the fiber array needs to be moved, which is why the fiber array should be placed on a movable workbench, because the fiber array can be easily Can now move with the movement of the workbench. Moreover, the general movable workbench is a three-dimensional movable workbench, which can accurately control its moving distance. However, during the moving process, the position of the fiber array may be slightly shifted. In order to be able to detect and correct this small deviation, some existing technical solutions cannot overcome it due to technical limitations when performing measurements. These deviations lead to insufficient measurement accuracy.

In the present invention, a long main line is generally set on the measurement template, and the main line provides auxiliary calibration information. For example, please refer to FIG. 5A and FIG. 5B , the straight line in the figure is the main line, and the circle is the fiber core. When the positional relationship between the collected previous image a and the next image b deviates, the main line is not on a straight line and needs to be corrected. After correction, the main lines on image a and image b are on a straight line . What needs to be explained here is that because the width of the main line is too wide, it will affect the accuracy of the measurement, but the width is too narrow, which is not conducive to the later image processing, so the setting of the width of the main line should be selected according to the actual measurement needs. After trial and error, it can be clearly known that the line width of the main line is preferably between 1 μm and 5 μm.

In addition to the main line, several short lines can also be set on the measurement template. The short lines are used to encode the fiber cores in the end face image of the optical fiber array. The coding rule of the short lines is generally to encode once for each fiber core. The distance between them is the standard core distance of the fiber array. Taking the 32-channel optical fiber array as an example, the standard core distance is 127 μm, so the distance between the short lines on the template is 127 μm, then this template can be used for the measurement of the core distance of the fiber array with the number of channels less than 32 and the standard core distance of 127 μm . Moreover, the short line can form a certain angle with the main line as shown in Figure 2, and can also be perpendicular to the main line (as shown in Figure 6). Since the short line can be used to mark the image when multiple images are collected to prevent splicing errors when multiple images are stitched together, the setting of the short line is not limited to the way shown in Figure 4 and Figure 6. As long as it can play the role of mark identification.

It should be noted here that the number of channels of the optical fiber array mentioned above is the number of optical fibers contained in the optical fiber array, and the core on the end face of the optical fiber array is the end face of the optical fiber. That is to say, a fiber array with 1 channel contains 1 fiber, and there is 1 fiber core on the end face of the fiber array; a fiber array with 32 channels contains 32 fibers, and there are 32 fibers on the end face of the fiber array. core.

In addition, the above-mentioned calibration template and the measurement template are generally made of basically the same material and processing technology, and their sizes are also basically the same. Therefore, the two can be made into one template, that is to say, on one template, one part is a calibration template and the other part is a measurement template, which is more convenient to use and makes the process of replacing the template easier.

In order to be able to measure accurately, the optical fiber array to be tested is usually fixed on a workbench for measurement, and the workbench is a movable platform, and a fixture is set on the workbench to cover the fiber array and its measurement The template on the end face is fixed to prevent its displacement from affecting the measurement. There is generally a high-precision control device inside the workbench, which is used to control the table top of the workbench in the horizontal or vertical direction, and move it precisely as required. Since the fiber array and template are fixed on the workbench, when the table top of the workbench moves, the fiber array and template will also move accordingly.

What needs to be explained here is that since the end face of a general optical fiber array has an 8° inclined surface, as shown in Figure 7, if the optical fiber array is placed on a common horizontal fixture, then the measured end face will have a distance from the vertical plane. The included angle of 8°, during image acquisition, the acquired image will be distorted due to the included angle. In order to solve this problem, the present invention will make a special fixture 1, and the fixture 1 will be set with an inclination angle of 8° accordingly. When the optical fiber array is placed on the fixture 1, the measured end face is perpendicular to the workbench plane, which is very good. It overcomes the problem of distortion during image acquisition. At the same time, in order to better fix the optical fiber array under test, the clamp 1 is usually provided with a baffle plate 2, which is used to prevent the optical fiber array from being inserted too far into the clamp; and a clamping part 3 is provided to fix the optical fiber array on the clamp. 1 to prevent the fiber array from falling off from the clamp 1. Since other components of the clamp 1 are similar to common clamps, no detailed description will be given here. It should be noted here that the jig 1 shown in FIG. 7 is only an exemplary design method. In actual application, as long as the jig can make the end surface to be tested perpendicular to the plane of the workbench and be fixed on the workbench.

Normally, a camera can be used to photograph the end face of the fiber array under test covered by the template. In order to facilitate post-processing, an image acquisition card is generally used to obtain digital video image information, store it and play it out as a hardware device. The specific process of collecting the measurement end face image is that the camera will capture the measurement end face of the measured optical fiber array through the template, and the image acquisition card will obtain the image information through the captured image, and then save the image information for future output and call.

In addition, according to the foregoing description, it can be clearly known that image information of all fiber cores cannot be obtained usually during one image acquisition process, which is also one of the technical difficulties in fiber array core measurement. In the prior art, the image information of only one fiber core is generally acquired at a time, and the image information obtained multiple times is collected, and then the information obtained multiple times is comprehensively processed, and finally the desired result is obtained, but the obtained result is not very accurate. And the image that the present invention gathers usually comprises two fiber cores at every turn, and its collection process is generally, collect the image of the 1st fiber core and the 2nd fiber core for the first time, then move the optical fiber array under test by moving the workbench , until it is moved to a position suitable for camera shooting, and then the second collection is performed to obtain the images of the second and third fiber cores. After receiving this collection, continue to move the workbench, and then collect. This is repeated until all the fiber cores of the entire measurement end face are collected, and the entire image collection is completed.

For example, in the existing 4-channel optical fiber array, that is, there are 4 fiber cores on the measuring end face, after covering the end face of the optical fiber array with the template, move the optical fiber array to a position suitable for camera shooting, so that the camera can just capture the first and After the shooting of the second fiber core, continue to move the fiber array so that the camera can shoot the second and third fiber cores. After the shooting, continue to move the fiber array so that the camera can shoot the third and third fiber cores. For the fourth fiber core, the image acquisition of the entire measurement end face is completed. In addition to the above shooting methods, other shooting methods can also be used, such as shooting the first and second fiber cores for the first time, and shooting the third and fourth fiber cores for the second time. Of course, in the actual operation process, different shooting methods can also be adopted according to the needs.

Step 105, according to the measurement template, according to the preset algorithm, sequentially splicing and restoring the multiple images collected, and processing them to obtain the processed image, according to the processed image and the error , to calculate the core position.

It can be known from step 102 that, in order to obtain images of the measurement end face of the entire optical fiber array, multiple image acquisitions are usually performed to obtain multiple images. In order to facilitate processing, the multiple images collected are usually spliced in order to restore them to an image of the entire optical fiber array measurement end face. It should be noted here that since image coding information is set on the measurement template covered on the measurement end face, when performing image splicing, it can be judged whether there is an error in the collected image according to the image coding information. For example, if the shooting method adopted is to shoot the first and second fiber cores for the first time, and the second and third fiber cores for the second time, then as shown in Figure 8A, the order of the images collected Correct, but if it is as shown in Figure 8B, it means that the collected images are arranged in the wrong order, or the fiber core was missed during shooting. Therefore, it can be judged whether there is an error in the collected image. The reason for the error may be that the image acquisition time is very fast. Usually, after the first image is taken, the workbench moves immediately and the next image is taken. During this process, the movement speed of the workbench may not keep up with the acquisition. An error occurs due to the speed of the image; or when the image is arranged, the order of the two images before and after is reversed, and so on. At the same time, the measurement template is also provided with image coding information, such as the main line in the middle of the measurement template. After the collected images are arranged in order, the offset of the fiber core in the image can be corrected according to the main line. Since it has been explained above, it will not be repeated here. The image coding information such as the main line and the short line set on the measurement template further improves the accuracy and reliability of the technical solution provided by the present invention. However, in some existing technical solutions, the measurement templates provided are usually continuous square frames. As shown in Figure 9, the square frames do not have the functions of correction and auxiliary splicing of the measurement templates provided by the present invention, thus affecting Measurement accuracy, so the technical solution provided by the present invention has higher measurement accuracy than the solution using measurement templates in the prior art.

In practical applications, in order to make the collected images clearer and easier to identify, a light source is usually set up, and the light emitted by the light source passes through the collimator lens and then enters the optical fiber for transmission, so that the core of the optical fiber on the collected image is a high Bright spots, which are more conducive to splicing and restoring the images according to the preset algorithm in the later stage, so that the results calculated according to the image processing are more accurate, and the measurement accuracy of the technical solution of the present invention is improved.

Please refer to FIG. 10, the process of processing the collected images may include the following steps:

Step 301, read the collected end-face image of the optical fiber array, and perform smoothing filtering preprocessing.

It is worth noting here that in the actual application process, the collected images may not be ideal due to the influence of image acquisition equipment or external conditions. In order to better obtain the required information from the images, usually Preprocess the image with smoothing filter. Of course, this is not a necessary step, and this step can be omitted if the collected images are very clear and fully meet the predetermined requirements.

Step 302, extracting the imaging region of the positioning fiber, ie the region of interest.

It can be seen from the foregoing that, since the visible light emitted by the set light source enters the optical fiber for transmission, the fiber core on the measurement end face of the fiber array appears bright, so that the imaging area of the fiber core can be extracted.

Step 303, performing sub-pixel edge extraction on the region of interest and locating the center of the circle.

Here, the binomial interpolation algorithm and other algorithms can be used to extract the edge of the region of interest, and then the least square fitting method or symmetric fitting method is used to determine the center of the circle.

Step 304, calculate the actual distance between the centers of the two fiber cores.

After the image is collected, the actual distance of the center of the fiber core is calculated according to the setting parameters of the image acquisition module and the magnification of the selected micro-magnification module.

For example, after the image processing module performs the above-mentioned processing on the image collected by the image acquisition module, the image shown in Figure 11 is obtained, then the black solid line circle in the figure is the fiber core, and the black dotted line frame is the two extracted regions of interest. The black straight line is the core distance to be calculated.

Since the smoothing filter preprocessing mentioned above, the extraction of the imaging region of the positioning optical fiber, the binomial interpolation algorithm and the least squares fitting method belong to the prior art, they will not be repeated here.

Since there is no final splicing restoration step in the prior art, what is obtained is only the positional relationship of a single fiber core relative to the standard quantity. However, the technical solution provided by the present invention can obtain the combined image of the entire measurement end face through splicing and restoration of the collected images, and then more accurately know the positional relationship of each fiber core on the measurement end face, further improving the technical solution. measurement accuracy.

Device example:

Please refer to FIG. 12 , which shows a structural diagram of a system for measuring the core distance of an optical fiber array provided by the present invention. The system includes a calibration light source, a calibration template (not shown in FIG. 12 ), a measurement template, a workbench, an image acquisition module and an image processing module.

Wherein, the calibration template is a special template used for calibrating system errors. The structure of the calibration template is generally shown in FIG. 2. A plurality of geometric figures are usually set in the calibration template. The size and relative position of the above-mentioned geometric figures are all known. In a preferred embodiment, the geometric figures are usually circular, that is, the calibration dots. The diameters of each calibration dot are the same, and the distance between the calibration dots is the same. The same, but in practical applications, calibration points with different diameters or spacings can be designed according to needs, and the calibration points are not limited to circles, but can also be other shapes such as squares.

In addition, the geometric figures on the calibration template are usually small in size. This is because the measurement of the fiber array core is usually at the nanoscale, so the magnification of the equipment used to collect images is generally relatively large. If the geometric figures are too large Large, when the image is collected, it is likely that the entire image has only one geometric figure or only a part of the geometric figure, so the information of the geometric figure cannot be obtained, and the relevant parameters cannot be calculated, and the diameter affects the measurement accuracy. Therefore, in the process of making the calibration template, it is necessary to design the size and spacing of the geometric figures according to the actual situation.

After making the calibration template, the calibration can be performed according to the following steps, and the specific process is shown in Figure 3.

Step 201, placing the calibration template in front of the image acquisition device;

Step 202, collecting images of calibration templates;

Step 203, detecting the calibration dot in the image;

Step 204, calculating relevant parameters of the image acquisition device.

In the prior art, there is usually no dedicated calibration template for optical fiber array measurement, so its measurement accuracy is often not ideal. However, the present invention provides a calibration template specially for the technical solution of measuring the fiber core position of the optical fiber array, which can effectively improve the measurement accuracy.

After the calibration is completed, the actual measurement process of the optical fiber array can be entered. During actual measurement, the calibration template needs to be replaced with a measurement template before subsequent steps can be performed.

The measurement template mentioned here is used to be placed at a position corresponding to the end face of the tested optical fiber array. The preferred embodiment is to cover the measured end face of the tested optical fiber array. The measurement template is the same as the previously described calibration template. Two different templates: the measurement template is used when actually measuring the fiber array under test; the calibration template is used when calibrating. Although the purposes of the two are different, their production materials and processes are basically the same. The templates are usually made of materials that are relatively transparent, small in thickness, good in strength, and low in thermal expansion coefficient, such as optical glass, quartz glass, engineering plastics, etc. Then the material is processed by micro-nano lithography, or semiconductor processing, etc., to make the required template, and its structure is shown in FIG. 4 . The measurement template includes image coding information. It can be seen from FIG. 4 that a thick main line is usually set in the middle of the measurement template, and short lines are also set on the main line. The main line and short lines here are image coding information. The coded information such as the main line and the short line set on the measurement template is usually processed by high-precision processing equipment, such as a high-precision interferometer, so as to ensure the accuracy of the measurement template, thereby ensuring the measurement accuracy of the entire measurement system .

In addition, the above-mentioned calibration template and the measurement template are generally made of basically the same material and processing technology, and their lengths are also basically the same. Therefore, the two can be made into one template, that is to say, on one template, one part is a calibration template and the other part is a measurement template, which is more convenient to use and makes the process of replacing the template easier.

The prepared measurement template is fixed on a movable workbench when in use. In addition to fixing the measurement template, the workbench is also used to fix the fiber array under test and drive the fiber array under test to move.

The workbench usually includes a three-dimensional mobile platform capable of moving in three dimensions. There is generally a control device inside the workbench. Because the table top of the control workbench moves precisely in the horizontal or vertical direction, different types of workbenches have different movement accuracy, which will also affect the measurement accuracy of the entire measurement system. Therefore, when choosing a workbench, the choice should be made according to the required measurement accuracy. Since the movement of the worktable is controlled by the control device and basically does not require manual intervention, its movement accuracy is very high and its movement speed is also very fast, so that the accuracy and speed of the entire measurement system are relatively high.

It should be noted that since the end face of a general fiber array has an 8° inclined surface, as shown in Figure 7, if the fiber array is placed on an ordinary horizontal fixture, the measured end face will be 8° from the vertical plane. During image acquisition, the acquired image will be distorted due to the included angle. In order to solve this problem, the present invention will make a special fixture 1, and the fixture 1 will be set with an inclination angle of 8° accordingly. When the optical fiber array is placed on the fixture 1, the measured end face is perpendicular to the workbench plane, which is very good. It overcomes the problem of distortion during image acquisition. At the same time, in order to better fix the optical fiber array under test, the clamp 1 is usually provided with a baffle 2, which is used to prevent the optical fiber array from being inserted into the clamp 1 from excessive insertion; Fixture 1 to prevent the fiber array from falling off from the fixture 1. Since other components of the fixture are similar to general fixtures, no detailed description will be given here.

After the fiber array is fixed, the image acquisition module can be used to collect images of the measurement end face of the fiber array. The image acquisition module usually includes a camera for photographing the end face of the tested optical fiber array covered by the template. In order to facilitate post-processing, the image acquisition module generally also includes an image acquisition card, which is a hardware device that can acquire digital video image information, store and play it out. Usually, the specific process of the image acquisition module to collect and measure the end-face image is that the camera will capture the measured end-face of the measured optical fiber array through the template, and the image acquisition card will obtain the image information through the captured image, and then save the image information. for future output calls.

In addition, under normal circumstances, the image acquisition equipment is usually marked with parameters such as image magnification, but in practical applications, due to the processing errors or wear and tear during its manufacturing process and use, the image acquisition equipment may be damaged. The actual magnification and other parameters are not the indicated values. Therefore, in the actual measurement process, the calibration template is usually used to calibrate the error of the image acquisition device and the entire measurement system. In addition, a CCD camera, a CMOS camera, or other camera devices that can be used for image acquisition can be used here.

It should be noted that the measurement end face image collected by the image collection module is an enlarged image. Since the core diameter of a general multimode fiber array is 62.5 μm, and the core diameter of a single-mode fiber array is 8 to 10 μm, it cannot be recognized by human eyes at all, so the system for measuring the core distance in a fiber array provided by the present invention also includes The microscopic magnification module is used for enlarging the measuring end face, so as to obtain the enlarged measuring end face image. Wherein, the microscopic magnification module may be an optical microscope, or it may be a device capable of magnifying the measurement end face. Therefore, in a preferred embodiment, the camera in the image acquisition module photographs the measurement end face of the optical fiber array through an optical microscope. Moreover, when selecting the micromagnification device as the micromagnification module, it should ensure that the image resolution requirements are met so that the microscopic field of view includes at least two adjacent wire cores.

In practical applications, in order to make the collected images clearer and easier to identify, a light source is usually set up, and the light emitted by the light source passes through the collimator lens and then enters the optical fiber for transmission, so that the core of the optical fiber on the collected image is a high The bright light point is more conducive to the processing of the later image, and then makes the result calculated according to the image processing more accurate, and improves the measurement accuracy of the technical solution of the present invention. It should be noted here that the light source can be a white light source, an LED light source, or a laser light source, as long as it can increase the light intensity enough, and the light intensity of the light source is based on the system magnification, the image Set the resolution requirements and other conditions. Generally speaking, the higher the image resolution requirement, the larger the system magnification, and the stronger the intensity of the light source required.

After the image acquisition module has collected the images, the image processing module needs to be used to process the collected images. It can be known from the foregoing that in order to acquire the images of the entire optical fiber array measurement end face, multiple image acquisitions are usually performed to obtain multiple images. Therefore, the image processing module will splicing and restoring the multiple acquired images in sequence, and Processing is performed to calculate the core position according to the template.

Please refer to FIG. 10, the process of processing the collected images may include the following steps:

Step 301, read the collected end face image of the optical fiber array, and perform smoothing filtering preprocessing;

Step 302, extracting the imaging region of the positioning optical fiber, that is, the region of interest;

Step 303, using the binomial interpolation algorithm to perform sub-pixel level edge extraction on the area and using the least squares fitting method to locate the center of the circle;

Step 304, calculate the actual distance between the centers of the two fiber cores according to the setting parameters of the image acquisition module and the magnification ratio of the selected micro-magnification module.

Since the smoothing filter preprocessing mentioned above, the extraction of the imaging region of the positioning optical fiber, the binomial interpolation algorithm and the least squares fitting method belong to the prior art, they will not be repeated here.

Since there is no final splicing restoration step in the prior art, what is obtained is only the positional relationship of a single fiber core relative to the standard quantity. However, the technical solution provided by the present invention can obtain the combined image of the entire measurement end face through splicing and restoration of the collected images, and then more accurately know the positional relationship of each fiber core on the measurement end face, further improving the technical solution. measurement accuracy.

At the same time, the measurement system provided by the present invention does not require a complex high-precision macro-micro double-drive sub-micron positioning platform or a precision grating, and only needs to extract the measurement results through image stitching and pattern recognition to realize high-precision and automatic fiber array measurement. Precision measurement, compared with the existing large-scale measurement equipment, has the advantages of compact equipment and low cost.

As for the device embodiment of the present invention, since it is basically similar to the method embodiment, the description is relatively simple, and for relevant parts, please refer to part of the description of the method embodiment.

The method and system for measuring the position of the fiber core of an optical fiber array provided by the present invention have been described in detail above. The technical solution provided by the present invention uses a specially designed calibration template to calibrate the measurement system, and then covers the measurement end face of the entire optical fiber array with the measurement template, and then uses a precision micro-motion workbench to move the measured optical fiber array, and at the same time continuously shoots through microscopic amplification Using a specially designed measurement template to correct the offset and twist angles of two adjacent optical fibers during the movement process, it is used as an auxiliary parameter for the stitching of continuously captured microscopic images. After splicing and restoring the multiple microscopic images taken, sub-pixel precision target recognition and information extraction are performed on the restored microscopic images, and then the fiber core position is calculated according to the design parameters of the microscopic module.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the present invention. within the scope of protection.

Claims (8)

1. a kind of fiber array fibre core is away from precision measurement method, it is characterised in that methods described includes：

Step A, is demarcated using default calibrating template, so as to obtain error；

Step B, by default measurement module, gathers tested optical fiber array end view drawing picture, the measurement module is tested with described Fiber array end face correspondence is fixed on moveable workbench, has source light in the optical fiber of the fiber array in conduction, The image gathered first is included after at least two fibre cores, mobile work platform, then gathers the tested optical fiber array end view drawing picture, then The image of secondary collection includes at least two fibre cores, and at least one fibre core be fibre core in last acquired image it One, continue to press equidirectional mobile work platform, the process of repeated acquisition image, until the whole tested optical fiber array end face is adopted Collection is finished；Wherein, supplemental characteristic for providing image mosaic is provided with the measurement module and as measurement standard amount Image coding information, described image coding information is to be arranged at a main line in the measurement module centre position and in institute State according to some short-terms of the standard fibre core away from equidistantly distributed on main line, the measurement module is added by micro-nano photoetching process Work is formed；

Step C, according to the measurement module, according to default algorithm, splicing recovery is carried out by the multiple image of collection in order, And it is handled, the image after being handled, according to the image after the processing and the error, calculate fibre core position.

2. according to the method described in claim 1, it is characterised in that described image is the measurement end view drawing Jing Guo micro- amplification Picture.

3. according to the method described in claim 1, it is characterised in that the step C also includes：Fiber array is placed in removable On the special fixture of workbench.

4. according to the method described in claim 1, it is characterised in that the step B also includes：End face image is measured in collection Before, by light source by fiber optic conduction, fibre core is presented highlighted.

5. a kind of fiber array fibre core is away from precision measurement system, it is characterised in that the system includes：

Calibrating template, the error for micro- amplification module in calibration system；

Measurement module, for being placed in the position corresponding with tested optical fiber array end face；Use is provided with the measurement module In the supplemental characteristic and the image coding information as measurement standard amount that provide image mosaic, described image coding information is to set Be placed in a main line in the measurement module centre position and on the main line according to standard fibre core away from equidistantly distributed Some short-terms, the measurement module is processed by micro-nano photoetching process；

Workbench, for fixed placement tested optical fiber array, and can drive tested optical fiber array to move；

Image capture module, for by light source, collection to be superimposed the tested optical fiber array end view drawing picture of measurement module, first The image of secondary collection includes at least two fibre cores, and after mobile work platform, the tested optical fiber array end view drawing picture is gathered again, The image gathered again includes at least two fibre cores, and at least one fibre core be fibre core in last acquired image it One, after mobile work platform at same direction is continued, the process of described image collection is repeated, until the whole tested optical fiber battle array Row end face is collected to be finished；

Image processing module, for according to the measurement module, according to default algorithm, the multiple image of collection to be entered in order Row splicing is restored, and it is handled, and calculates fibre core position.

6. system according to claim 5, it is characterised in that the micro- amplification module, for measurement by magnification end face, from And the measurement end face image being amplified；The enlargement ratio of the micro- amplification module at least makes the image of collection include two Fibre core.

7. system according to claim 5, it is characterised in that the system also includes fixture, for fiber array to be put In on movable working platform.

8. system according to claim 5, it is characterised in that the system also includes light source, for by fiber optic conduction, Fibre core is presented highlighted.