A method and apparatus for measuring the length of optical fibers

Abstract

This invention discloses a method for measuring the length of optical fibers. After the optical fiber is released from the fiber delivery tray and fixed on the fiber take-up tray, a first and a second dividing color ring are marked on the fiber. The fiber is moved to the right by a first predetermined distance, and the distance between the second and first dividing color rings is calculated. A first position color ring is then sprayed to the right of the first dividing color ring. The fiber is moved to the right by a second predetermined distance, and a third dividing color ring is sprayed. The fiber is moved to the right by the first predetermined distance, and the distance between the third and second dividing color rings is calculated. A second position color ring is then sprayed. This process is repeated to spray the nth dividing color ring and its corresponding position color ring until the fiber delivery tray finishes delivering the fiber. In this invention, the length information represented by the position color rings is obtained through measurement, eliminating errors in the marking process. This high-precision optical fiber length measurement has significant application value in the field of optical fiber winding for optical fiber gyroscopes.

Description

Technical Field

[0001] This invention belongs to the field of precision measurement. Specifically, it relates to a method for measuring the length of optical fibers, and also to an optical fiber length measuring device suitable for the optical fiber winding of optical fiber gyroscopes. Background Technology

[0002] High-precision fiber optic length measurement has significant application value in the field of fiber optic gyroscope fiber optic loop fabrication. The fiber optic loop is a core component of interferometric fiber optic gyroscopes. To achieve higher measurement accuracy and better environmental adaptability, precise length measurement and control of the looped fiber is typically required. Traditional fiber optic length measurement methods mainly include optical time domain reflectometers (OTDR), optical frequency domain reflectometers (OFDR), and optical low coherence reflectometers (OLCR), with the following characteristics:

[0003] (1) OTDR is based on the principles of backscattering Rayleigh scattering and Fresnel reflection. Its advantage is that the measurement length can reach hundreds of kilometers, but its disadvantage is that the accuracy is poor and can only reach the centimeter level.

[0004] (2) The principle of OFDR for measuring fiber length is to modulate the frequency of the light source. The beat frequency of the signal on the detector will increase with the distance of the scattering point, and the energy on the detector is proportional to the size of the scattering point. The measurement accuracy is higher than that of OTDR, reaching the millimeter level; the measurement range is larger than that of OLCR, with a length of several kilometers. However, OFDR has very high requirements for the laser source of the system, requiring good coherence and stability.

[0005] (3) The advantages of OLCR are its simple structure and high testing accuracy, up to 10 μm. The disadvantage is its small dynamic range, with a maximum measurable range of only a few centimeters.

[0006] Although the above three methods can measure the length of optical fibers, they are costly, inconvenient to use, and cannot determine the length of optical fibers by direct observation.

[0007] Color-ringed optical fibers are made by spraying identical color rings at fixed intervals onto the optical fiber. The length of the fiber is determined by calculating the number of color rings. However, during the spraying process, if the optical fiber vibrates, it will cause errors in the spraying interval distance. This error will cause the calculated fiber length to differ from the actual fiber length. Summary of the Invention

[0008] This invention addresses the problem that the calculated fiber length does not match the actual fiber length during the spraying process of color-ringed optical fibers due to errors in the spraying process. It proposes a fiber length measurement method and a fiber length measurement device.

[0009] The above-mentioned objectives of the present invention are achieved through the following technical means:

[0010] An optical fiber length measuring device includes a fiber feeding reel and a fiber take-up reel. The optical fiber fed from the fiber feeding reel is fixed on the fiber take-up reel. The optical fiber between the fiber feeding reel and the fiber take-up reel is arranged on a left guide roller and a right guide roller. Along the direction from the fiber feeding reel to the fiber take-up reel, above the optical fiber between the fiber feeding reel and the fiber take-up reel, a left dividing color ring inkjet printer, a left camera, a right dividing color ring inkjet printer, a right camera, and a position color ring inkjet printer are arranged in sequence facing the surface of the optical fiber. An encoder is arranged on the fiber take-up reel. The distance between the left dividing color ring inkjet printer and the right dividing color ring inkjet printer is equal to the distance between the left camera and the right camera.

[0011] A method for measuring the length of optical fiber includes the following steps:

[0012] Step 1: Release the optical fiber from the fiber delivery tray and then fix it on the fiber take-up tray;

[0013] Step 2: Start the left and right dividing color ring inkjet printers to spray the second dividing color ring and the first dividing color ring onto the optical fiber.

[0014] Step 3: Start the fiber take-up reel. Based on the encoder reading on the take-up reel, move the optical fiber to the right by the first set distance. Start the left and right cameras to take the first shot, obtain the first shot image from the left camera and the first shot image from the right camera, and calculate the distance between the second dividing color ring and the first dividing color ring based on the first shot image from the left camera and the right camera.

[0015] Step 4: Start the position color ring inkjet printer and spray the corresponding first position color ring to the right of the first dividing color ring;

[0016] Step 5: Start the fiber take-up reel. Based on the encoder reading on the take-up reel, move the fiber to the right by the second set distance. Start the left dividing color ring inkjet printer to spray a new dividing color ring onto the optical fiber, at a distance of... The value is equal to the distance between the left and right cameras;

[0017] Step 6: Start the fiber take-up reel. Based on the encoder reading on the take-up reel, move the optical fiber to the right by the first set distance. Start the left and right cameras to take the nth shot, obtain the left camera image and the right camera image of the nth shot, and calculate the distance between the new sprayed color separation ring and the previous sprayed color separation ring based on the left and right camera images obtained in the nth shot.

[0018] Step 7: Start the position color ring inkjet printer and spray the corresponding position color ring to the right of the previously sprayed dividing color ring;

[0019] Step 8: Repeat steps 5 to 7 until the fiber feeding tray finishes feeding.

[0020] As described above in step 1, the optical fiber between the fiber feeding tray and the fiber taking tray is set on the left fiber guide wheel and the right fiber guide wheel.

[0021] As described above, the first set distance The numerical value is equal to the numerical value of the distance between the left dividing color ring inkjet printer and the left camera.

[0022] As mentioned above, the distance between the second and first dividing color rings, and the distance between the newly painted dividing color ring and the previously painted dividing color ring. Based on the following formula:

[0023] ,

[0024] in, The distance between the left and right dividing color ring inkjet printers. This represents the number of pixels by which the center point of the (n+1)th dividing color wheel deviates horizontally from the center point of the left camera image during the nth shot. ξ is the number of pixels by which the center point of the nth dividing color ring deviates from the center point of the right camera image in the horizontal direction during the nth shot, ξ is the horizontal width of the shooting field of view in pixels, and n is the number of shots.

[0025] As mentioned above, when the center point of the color wheel is located to the left of the exact center of the camera image, and When the value is negative, and the center point of the dividing color ring is located to the right of the exact center of the camera image, and The value is positive.

[0026] As mentioned above, the first dividing color ring is the starting dividing color ring, and the position information represented by the corresponding position color ring reading is 0mm.

[0027] As described above, the second set distance The value is the distance between the left and right dividing color ring inkjet printers minus the distance between the left dividing color ring inkjet printer and the left camera.

[0028] As mentioned above, in step 7, the position information of the color ring corresponding to the previous sprayed dividing color ring is... Where n is the number of shots. The distance between the new spray-painted dividing color ring corresponding to the (n-1)th shot and the previous spray-painted dividing color ring.

[0029] The present invention has the following advantages over the prior art:

[0030] 1. Mark the fiber with a separator color ring and a corresponding position color ring. The separator color ring represents the length and position of the fiber, and the position color ring reading indicates the position information of the separator color ring. The fiber length can be accurately and quickly identified by using the separator color ring and the corresponding position color ring.

[0031] 2. Each time the position color ring corresponding to the dividing color ring is marked, the length information represented by the reading of the position color ring is obtained by measurement, thus eliminating the error in the marking process.

[0032] 3. By reading the position readings of the color rings corresponding to any two separator color rings, the difference between the two readings can be calculated to accurately obtain the fiber length between the two separator color rings. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the optical fiber length measuring device.

[0034] Figure 2 A flowchart of the fiber optic length measurement method;

[0035] Figure 3 This is a schematic diagram showing an image without deviation.

[0036] Figure 4 This is a schematic diagram illustrating negative image deviation.

[0037] Figure 5 This is a schematic diagram illustrating positive image deviation.

[0038] Among them, 1-fiber feeding reel; 201-left fiber guide roller; 202-right fiber guide roller; 301-left dividing color ring inkjet printer; 302-right dividing color ring inkjet printer; 401-left camera; 402-right camera; 5-position color ring inkjet printer; 6-fiber take-up reel. Detailed Implementation

[0039] To facilitate understanding and implementation of the present invention by those skilled in the art, the present invention will be further described in detail below with reference to embodiments. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0040] Example 1:

[0041] like Figure 1As shown, an optical fiber length measuring device includes a fiber feeding reel 1 and a fiber take-up reel 6. The optical fiber fed from the fiber feeding reel 1 is fixed on the fiber take-up reel 6. The optical fiber between the fiber feeding reel 1 and the fiber take-up reel 6 is arranged on a left guide roller 201 and a right guide roller 202, which support and guide the optical fiber. Along the direction from the fiber feeding reel 1 to the fiber take-up reel 6, above the optical fiber between the fiber feeding reel 1 and the fiber take-up reel 6, a left dividing color ring inkjet printer 301, a left camera 401, a right dividing color ring inkjet printer 302, a right camera 402, and a position color ring inkjet printer 5 are arranged sequentially facing the surface of the optical fiber.

[0042] Left and right separator color ring inkjet printers 301 and 302 are used to spray separator color rings, which mark the fiber length position. The fiber length is determined by calculating the position difference between different separator color rings. Position color ring inkjet printer 5 sprays a position color ring on the right side of the separator color rings (the side closer to the fiber take-up tray 6 is considered right). The reading of the position color ring represents the position information of the separator color rings. Left and right cameras 401 and 402 observe the images of the separator color rings and calculate the distance between adjacent separator color rings by reading their images.

[0043] Furthermore, the distance between the left dividing color ring inkjet printer 301 and the right dividing color ring inkjet printer 302 is equal to the distance between the left camera 401 and the right camera 402, and is set by a mechanical ruler.

[0044] Furthermore, the fiber take-up reel 6 is equipped with an encoder. During the fiber take-up process, the distance the optical fiber moves is controlled by the metering reading of the encoder. If the encoder reading increases by 1m, then the fiber take-up reel 6 will theoretically take up 1m of fiber, that is, the optical fiber will theoretically move 1m.

[0045] Example 2:

[0046] For ease of description, the distance between the left dividing color ring inkjet printer 301 and the right dividing color ring inkjet printer 302 is denoted as the distance. Then the distance between the left camera 401 and the right camera 402 is also a distance. The distance between the left dividing color ring inkjet printer 301 and the left camera 401 is recorded as the distance. The distance is recorded as the first preset distance the optical fiber moves to the right, controlled by the encoder reading on the fiber take-up reel 6. The second predetermined distance by which the optical fiber moves to the right, controlled by the encoder reading on the fiber take-up reel 6, is denoted as... Among them, distance The magnitude of the value and the distance The values ​​are equal, and the distance is equal. The magnitude of the value and the distance The values ​​are equal.

[0047] like Figure 2 As shown, a fiber optic length measurement method, utilizing the fiber optic length measurement device described in Example 1, includes the following steps:

[0048] Step 1: Fix the optical fiber.

[0049] The optical fiber is released from the fiber release tray 1 and fixed on the fiber take-up tray 6, and the optical fiber between the fiber release tray 1 and the fiber take-up tray 6 is set on the left fiber guide wheel 201 and the right fiber guide wheel 202.

[0050] Step 2: Start the left dividing color ring inkjet printer 301 and the right dividing color ring inkjet printer 302 to spray the second dividing color ring and the first dividing color ring onto the optical fiber.

[0051] Step 3: Start the fiber take-up reel 6. Based on the encoder reading on the fiber take-up reel 6, move the optical fiber to the right by the first set distance. This process ensures that the first dividing color ring stops within the field of view of the right camera 402, and the second dividing color ring stops within the field of view of the left camera 401. The left camera 401 and the right camera 402 are then activated to take the first shot, obtaining the right camera image (the right camera image corresponding to the first dividing color ring) and the left camera image (the left camera image corresponding to the second dividing color ring) from the first shot. The distance between the second dividing color ring and the first dividing color ring is then calculated based on the right camera image and the left camera image.

[0052] Since the optical fiber may slide on the take-up reel 6, the distance represented by the difference in the encoder readings on the take-up reel 6 is different from the actual distance the optical fiber moves to the right. Therefore, when confirming the spacing between adjacent dividing color rings, the spacing between the left camera image captured by the left camera 401 and the right camera image captured by the right camera 402 shall be used as the standard.

[0053] like Figure 3 As shown, the shooting fields of both the left camera 401 and the right camera 402 are divided into regions of size M×M (horizontal × vertical). The shooting field of view of the left camera 401 is the same size and has the same resolution as that of the right camera 402. Each region represents one pixel of the camera image, and the shaded area is the center point of the dividing color wheel. If the center point of the dividing color wheel is located at the exact center of the camera image, the image is considered to be without deviation.

[0054] like Figure 4 As shown, if the center point of the dividing color wheel is located to the left of the center of the camera image, the image is considered to be negatively offset.

[0055] like Figure 5 As shown, if the center point of the dividing color wheel is located to the right of the exact center of the camera image, the image is considered to be deviating.

[0056] During the first capture, the number of pixels in the left camera image where the center point of the second dividing color ring deviates from the center point of the left camera image along the horizontal direction (the direction of the fiber optic extension) is recorded. In the right camera image, the number of pixels by which the center point of the first dividing color ring deviates laterally from the center point of the right camera image is [number missing]. Then, the actual distance between the second dividing color wheel and the first dividing color wheel is calculated as follows: Therefore, by analogy, in the nth shot, the right camera image is the camera image corresponding to the nth dividing color wheel, and the left camera image is the camera image corresponding to the (n+1)th dividing color wheel. The actual distance between the (n+1)th and nth dividing color wheels... , where n is the number of shots.

[0057] in, The spacing between the left dividing color ring inkjet printer 301 and the right dividing color ring inkjet printer 302. This refers to the number of pixels by which the center point of the (n+1)th dividing color ring deviates from the center point of the left camera image along the horizontal direction (the direction of fiber optic extension) during the nth shot. This represents the number of pixels by which the center point of the nth dividing color ring deviates from the center point of the right camera image along the horizontal direction (the direction of fiber extension); when it is a negative image deviation... and The value is negative; when the image deviates positively, and The value is positive. ξ is the horizontal width of the pixels in the field of view. In this embodiment, ξ is 1mm.

[0058] Step 4: Activate the position color ring inkjet printer 5. Spray the corresponding first position color ring to the right of the first dividing color ring. The reading of the first position color ring represents the position information of the first dividing color ring. The position information of the first dividing color ring is the starting position, set to... .

[0059] The position color bands are defined as follows: the unit indicated by the position color bands is mm. Following the resistance value definition method of color-coded resistors, the position color bands consist of 10 color bands, using a decimal system, with the left side representing the high-order digit and the right side the low-order digit. The numerical values ​​represented by each color are shown in Table 1 below.

[0060] Table 1

[0061]

[0062] For example, if the colors of a position on the color wheel are arranged from left to right as shown in Table 2, Table 2 is an example table of color wheels.

[0063] Table 2

[0064]

[0065] Therefore, the corresponding position information is 28961304mm, which means that the distance from the color ring at this position to the starting position is 28961.304m.

[0066] In this implementation, the colors of the first dividing color wheel are shown in Table 3 below. Table 3 is the color table of the first dividing color wheel.

[0067] Table 3

[0068]

[0069] This indicates that the first dividing color ring is the starting position, and the position information is that the fiber length is 0mm.

[0070] Step 5: Start the fiber take-up reel 6. Based on the encoder reading on the fiber take-up reel 6, move the optical fiber to the right by the second set distance. Start the left dividing color ring inkjet printer 301 to spray a new dividing color ring onto the optical fiber.

[0071] Step 6: Start the fiber take-up reel 6. Based on the encoder reading on the fiber take-up reel 6, move the optical fiber to the right by the first set distance. This process ensures that the newly painted dividing color ring is within the field of view of the left camera 401, and that the previously painted dividing color ring is within the field of view of the right camera 402. The left and right cameras 401 and 402 are then activated to take the nth shot, obtaining the left camera image (corresponding to the newly painted dividing color ring) and the right camera image (corresponding to the previously painted dividing color ring). The distance between the newly painted dividing color ring and the previously painted dividing color ring is calculated based on these images. .

[0072] in, The spacing between the left dividing color ring inkjet printer 301 and the right dividing color ring inkjet printer 302. This refers to the number of pixels by which the center point of the newly sprayed color-separating ring deviates from the center point of the left camera image along the horizontal direction (the direction of fiber optic extension) during the nth shot. For the nth shot, the number of pixels by which the center point of the previously sprayed dividing color ring deviates from the center point of the right camera image along the horizontal direction (the direction of the fiber optic extension).

[0073] Step 7: Start the position color ring inkjet printer 5 and spray the corresponding position color ring to the right of the previously sprayed dividing color ring.

[0074] The position information of the color ring corresponding to the right side of the last sprayed color ring is: n is the number of shots. The distance between the new spray-painted dividing color ring corresponding to the (n-1)th shot and the previous spray-painted dividing color ring.

[0075] Step 8: Repeat steps 5-7 until fiber feeding tray 1 finishes feeding.

[0076] Since each separator color ring is marked with a corresponding position color ring, the position information of the separator color rings can be obtained by reading the readings contained in the position color rings corresponding to any two separator color rings, and the fiber length between the two separator color rings can be obtained by subtracting them.

[0077] When using marked optical fibers for fiber optic gyroscope fiber optic winding, after determining the reading of the fiber winding center point, the winding length can be accurately determined by reading the reading of the position color ring corresponding to the separator color ring on the fiber optic during the winding process.

[0078] It should be noted that the specific embodiments described in this invention are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for measuring the length of an optical fiber, using an optical fiber length measuring device, the optical fiber length measuring device comprising a fiber feeding reel (1) and a fiber take-up reel (6), the optical fiber fed out by the fiber feeding reel (1) is fixed on the fiber take-up reel (6), the optical fiber between the fiber feeding reel (1) and the fiber take-up reel (6) is arranged on a left guide roller (201) and a right guide roller (202), along the direction from the fiber feeding reel (1) to the fiber take-up reel (6), above the optical fiber between the fiber feeding reel (1) and the fiber take-up reel (6) are arranged in sequence a left dividing color ring inkjet printer (301), a left camera (401), a right dividing color ring inkjet printer (302), a right camera (402) and a position color ring inkjet printer (5) facing the surface of the optical fiber, an encoder is arranged on the fiber take-up reel (6), the distance between the left dividing color ring inkjet printer (301) and the right dividing color ring inkjet printer (302) is equal to the distance between the left camera (401) and the right camera (402); characterized in that, The above-mentioned fiber length measurement method includes the following steps: Step 1: Release the optical fiber from the fiber release tray (1) and then fix it on the fiber take-up tray (6); Step 2: Start the left dividing color ring inkjet printer (301) and the right dividing color ring inkjet printer (302) to spray the second dividing color ring and the first dividing color ring on the optical fiber; Step 3: Start the fiber take-up reel (6). Based on the encoder reading on the fiber take-up reel (6), move the optical fiber to the right by the first set distance. Start the left camera (401) and the right camera (402) to take the first shot, obtain the left camera image and the right camera image of the first shot, and calculate the distance between the second dividing color ring and the first dividing color ring based on the left camera image and the right camera image obtained in the first shot. Step 4: Start the position color ring inkjet printer (5) and spray the corresponding first position color ring on the right side of the first dividing color ring; Step 5: Start the fiber take-up reel (6). Based on the encoder reading on the fiber take-up reel (6), move the optical fiber to the right by the second set distance. Start the left dividing color ring inkjet printer (301) to spray a new dividing color ring onto the optical fiber, at a distance of... The value is equal to the distance between the left camera (401) and the right camera (402); Step 6: Start the fiber take-up reel (6). Based on the encoder reading on the fiber take-up reel (6), move the optical fiber to the right by the first set distance. Start the left camera (401) and the right camera (402) to take the nth shot, obtain the left camera image and the right camera image of the nth shot, and calculate the distance between the new sprayed dividing color ring and the previous sprayed dividing color ring based on the left camera image and the right camera image obtained in the nth shot. Step 7: Start the position color ring inkjet printer (5) and spray the corresponding position color ring on the right side of the previously sprayed dividing color ring; Step 8: Repeat steps 5 to 7 until the fiber feeding tray (1) finishes feeding.

2. The optical fiber length measurement method according to claim 1, characterized in that, In step 1, the optical fiber between the fiber feeding tray (1) and the fiber taking tray (6) is set on the left fiber guide wheel (201) and the right fiber guide wheel (202).

3. The optical fiber length measurement method according to claim 1, characterized in that, First set distance The numerical value is equal to the numerical value of the distance between the left dividing color ring inkjet printer (301) and the left camera (401).

4. The optical fiber length measurement method according to claim 3, characterized in that, The distance between the second dividing color ring and the first dividing color ring, and the distance between the newly sprayed dividing color ring and the previously sprayed dividing color ring. Based on the following formula: ， in, The spacing between the left dividing color ring inkjet printer (301) and the right dividing color ring inkjet printer (302) is... This represents the number of pixels by which the center point of the (n+1)th dividing color wheel deviates horizontally from the center point of the left camera image during the nth shot. ξ is the number of pixels by which the center point of the nth dividing color ring deviates from the center point of the right camera image in the horizontal direction during the nth shot, ξ is the horizontal width of the shooting field of view in pixels, and n is the number of shots.

5. The optical fiber length measurement method according to claim 4, characterized in that, When the center point of the dividing color ring is located to the left of the exact center of the camera image, and When the value is negative, and the center point of the dividing color ring is located to the right of the exact center of the camera image, and The value is positive.

6. The optical fiber length measurement method according to claim 1, characterized in that, The first dividing color ring is the starting dividing color ring, and the position information represented by the corresponding position color ring reading is 0mm.

7. The optical fiber length measurement method according to claim 1, characterized in that, The second set distance The value is the distance between the left dividing color ring inkjet printer (301) and the right dividing color ring inkjet printer (302) minus the distance between the left dividing color ring inkjet printer (301) and the left camera (401).

8. The optical fiber length measurement method according to claim 6, characterized in that, In step 7, the position information of the color ring corresponding to the previously sprayed dividing color ring is... Where n is the number of shots. The distance between the new spray-painted dividing color ring corresponding to the (n-1)th shot and the previous spray-painted dividing color ring.

Images