CN111732335A - Method for restoring concentricity of optical fiber preform - Google Patents
Method for restoring concentricity of optical fiber preform Download PDFInfo
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- CN111732335A CN111732335A CN202010446134.1A CN202010446134A CN111732335A CN 111732335 A CN111732335 A CN 111732335A CN 202010446134 A CN202010446134 A CN 202010446134A CN 111732335 A CN111732335 A CN 111732335A
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- optical fiber
- concentricity
- acid
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C15/00—Surface treatment of glass, not in the form of fibres or filaments, by etching
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- Geochemistry & Mineralogy (AREA)
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- General Chemical & Material Sciences (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
Abstract
The invention relates to a method for restoring concentricity of an optical fiber preform, which is used for restoring the optical fiber preform with over-standard finished concentricity by pickling, changing the distance between the central point of a core layer and the central point of the finished optical fiber preform by pickling, and reducing the thickness of the over-standard side after pickling, so that the error of the concentricity of the optical fiber preform is reduced, the error of the concentricity of the finished optical fiber preform with over-standard finished optical fiber preform reaches the national standard range, the production qualification rate of the optical fiber is improved, the rejection of the preform is reduced, and the production cost is reduced.
Description
Technical Field
The invention relates to the field of optical fiber perform manufacturing, in particular to a method for restoring concentricity of an optical fiber perform.
Background
Core-to-core concentricity error definition of optical fiber: the core layer of the optical fiber is fitted into a circle and the center of the circle is determined, the cladding layer is fitted into a circle and the center of the circle is determined, and the difference of the positions of the centers of the two fitted circles is the concentricity. The national standard GB 9771.3-2008 stipulates that the concentricity error of a core package should be less than or equal to 0.6 um.
The optical fiber preform is a base material for drawing an optical fiber, and the quality of the optical fiber preform largely affects the quality of the optical fiber. Concentricity refers to the distance between a dot of the fiber core and a dot of bare fiber. National standards typically require that the optical fiber concentricity error be within 0.6 um. In the manufacturing process of the optical rod, certain concentricity error can be generated according to different manufacturing processes, and when the concentricity error is too large, the fusion loss of the optical fiber is large, so that the transmission efficiency of optical signals is influenced. The core-clad concentricity error of the optical fiber needs to be strictly controlled in the production process of the optical fiber, but the larger core-clad concentricity error is also one of the important reasons for the optical fiber rejection. Generally, when the concentricity error of an optical fiber drawn from a certain optical fiber preform is large (i.e. greater than 0.6 um), the drawing is stopped and the preform is discarded, which also increases the production cost of an enterprise.
In the existing patents for acid cleaning of optical fiber preforms, such as acid cleaning equipment or acid cleaning methods described in patents CN109320063A, CN207877593U, CN107902886A, CN206486438U, CN206666389U, and the like, the optical fiber preform is completely immersed in acid solution in a horizontal or vertical manner, and the surface of the optical fiber preform is cleaned by the corrosion action of acid, so as to remove impurities and pollution on the surface, thereby reducing the fiber breakage of the optical fiber preform during the drawing process. The apparatus and methods described in these patents only provide a clean surface contamination or contamination of the preform and do not restore concentricity of the preform.
In the prior art, control of the concentricity of the optical fiber preform is focused on the rod making process. The methods generally used are the following: 1. the centering of the handle and the mandrel is controlled in the process of welding the handle by the mandrel. 2. And (4) straightening the core rod, and controlling the integral circular jump of the core rod within a certain range. 3. A core rod having a relatively large core wrap is used in the core rod manufacturing process. Above all are control optical fiber perform concentricity error in process of production, but if the finished product optical fiber perform of optical fiber concentricity error problem or how to reduce the problem of finished product optical fiber perform concentricity appear, be the technical problem that this patent will solve.
Disclosure of Invention
In order to solve the technical problem, the invention provides a method for restoring concentricity of an optical fiber preform, which adopts the technical scheme that the method comprises the following steps:
step 1, horizontally placing an optical fiber preform with over-standard concentricity on a lifting platform in an acid tank, wherein one surface with over-standard concentricity faces downwards;
step 3, controlling the liquid level of the acid liquid to immerse half of the preform;
step 4, controlling the pickling time and the relative height of the prefabricated rod and the liquid level;
and 5, after pickling for a certain time, lifting the lifting platform or discharging acid in the acid tank, spraying the preform with distilled water, washing off residual acid liquor on the surface, and drying the surface of the preform with nitrogen or compressed air.
Furthermore, the concentricity overproof means that the error of the concentricity of the optical fiber is more than 0.6 um.
Further, the acid solution in the step 2 is hydrofluoric acid solution.
Further, in the step 2 and the step 3, the lifting platform is downwards moved to the bottom in the tank, acid liquor is injected again, and the liquid level is controlled to immerse half of the preform; or injecting acid liquor into the acid tank in advance, and controlling the lifting platform to enable the preform to be half immersed.
Further, the pickling time in the step 4 is determined according to the acid concentration and the immersion time.
Further, the relative height of the preform and the liquid level in step 4 means that when the liquid level is half of that of the preform, the lifting platform is controlled to slowly rise or the bath solution in the acid bath is controlled to slowly fall.
Furthermore, through the acid-washed optical fiber preform with the concentricity exceeding the standard, the surface exceeding the standard needs to be washed away by 0-1 mm.
Furthermore, a groove cover is arranged in the acid groove, and a water spraying hole is arranged on one side in the acid groove.
Further, the optical fiber preform is a single-mode or multi-mode optical fiber preform.
The invention has the beneficial effects that: the invention relates to a method for restoring concentricity of an optical fiber preform, which is used for restoring the optical fiber preform with over-standard finished concentricity by pickling, changing the distance between the central point of a core layer and the central point of the finished optical fiber preform by pickling, and reducing the thickness of the over-standard side after pickling, so that the error of the concentricity of the optical fiber preform is reduced, the error of the concentricity of the finished optical fiber preform with over-standard finished optical fiber preform reaches the national standard range, the production qualification rate of the optical fiber is improved, the rejection of the preform is reduced, and the production cost is reduced.
Drawings
FIG. 1 is a cross-sectional view of an optical fiber preform according to the present invention;
FIG. 2 is a schematic diagram of an acid tank used in an embodiment of the present invention;
as shown in the figure, 1 finished optical fiber perform external profile, 2 core layer profile, 3 optical fiber perform, 4 lifting platform, 5 acid tank, 6 acid inlet pipe, 7 water spray hole, 8 tank cover, 9 acid discharge pipe.
Detailed Description
The invention discloses a method for restoring concentricity of an optical fiber preform, which comprises the following steps:
step 1, horizontally placing an optical fiber preform with over-standard concentricity in a hydrofluoric acid tank, and placing one surface with over-standard concentricity downwards; the optical fiber prefabricated rod is a single-mode or multi-mode optical fiber prefabricated rod; the acid tank can be designed according to the size of the prefabricated rod and is suitable for repairing the prefabricated rods with various sizes.
And 3, controlling the liquid level of the acid liquid to enable the acid liquid to submerge half of the prefabricated rod.
And 4, controlling the acid washing time and the relative height of the prefabricated rod and the liquid level, and adopting a liquid level with a fixed height or controlling the liquid level to slowly descend at a speed of 1-10mm per hour until the liquid level is lower than the prefabricated rod. The liquid level can be a fixed liquid level, and the height of the liquid level or the height of the prefabricated rod can also be controlled in the acid washing process. The relative height of the prefabricated rod and the liquid level can be controlled by two methods, 1, the prefabricated rod rack rod mechanism (lifting platform) is controlled to be lifted slowly; 2, the acid discharge port is a hose and can be controlled to discharge acid slowly;
and 5, spraying distilled water on the preform to wash off residual acid liquid on the surface.
As shown in fig. 1, which is a cross-sectional view of an optical fiber preform, a large circle is an outer contour 1 of a finished optical fiber preform, a small circle is a core layer contour 2, a point a is a center point of the core layer contour, a point b is a center point of the finished optical fiber preform, a distance between the points a and b is a core package (optical fiber) concentricity error, and the distance between the points a and b after the optical fiber is drawn by national standard is not more than 0.6um from the optical fiber concentricity error.
Outer diameter of optical fiber: 125 um;
the national standard GB 9771.3-2008 states that the diameter of the cladding of the optical fiber is in the range of 125 +/-1 um.
The process of drawing the optical fiber preform into the optical fiber is a physical change process, the process of equal proportion change is performed between the cladding and the core layer in drawing, and the geometric proportion relation does not change at all, so the concentricity error of the finished rod = the concentricity error of the optical fiber X the outer diameter of the finished rod divided by the outer diameter of the optical fiber.
Example 1:
if an optical fiber preform with an outer diameter of 130mm is found to have a concentricity of 0.7um during drawing, the drawing is stopped, the error of the optical fiber concentricity is 0.7um, the error of the concentricity of a core rod and a finished rod in the corresponding 130mm preform is 0.728mm (the error of the concentricity of the finished rod = the error of the optical fiber concentricity X the outer diameter of the finished rod X divided by the outer diameter of the optical fiber), when the error of the concentricity is less than 0.6um, the error of the concentricity of the finished rod is less than 0.624mm according to the calculation formula of the error of the concentricity of the finished rod, the finished rod should be eroded from one side (0.728-0.624) × 2=0.208mm or more to make the error of the concentricity of the optical fiber within 0.6um, and because the refractive indexes of a core layer and a cladding layer of the prefabricated rod are different, the preform is irradiated by a flashlight with a power of 3W or more, the projection on the ground is observed, the core layer and the cladding layer and the strong light can be distinguished from the projection method is used to determine, the other side is the side needing to be corroded by acid cleaning.
The optical fiber perform 3 is horizontally placed in the acid tank 5, one surface needing to be corroded is downward, the perform on the lifting platform 4 vertically downward reaches the bottom of the acid tank, the tank cover 8 is covered, hydrofluoric acid with the concentration of 40% is added, the hydrofluoric acid enters from the acid inlet pipeline 6, the horizontal liquid level of the acid just does not exceed half height of the perform, the acid injection is stopped, the lifting platform is controlled, the platform is enabled to rise at a constant speed of 16.25mm/h, and the acid washing is finished after the acid washing for 4 h. (or the liquid level is controlled to slowly descend at the speed of 1-10mm per hour through the acid discharge pipeline 9), after the acid washing is finished, the lifting platform rises, the water spraying holes 7 on one side spray distilled water to wash out residual acid liquor on the surface of the prefabricated rod, and the surface of the prefabricated rod is dried by using nitrogen or compressed air. And opening the groove cover, taking out the optical fiber preform, drawing the preform, and measuring the core cladding (optical fiber) concentricity error of the optical fiber after drawing within the range of 0.1-0.2um which is far lower than the national standard requirement and is less than 0.6 um. The optical fibers drawn from the prefabricated rod after being processed by the method are all qualified, the production qualification rate of the optical fibers is greatly improved, the rejection rate of the optical fiber prefabricated rod is reduced, and the production cost is reduced.
Example 2:
if an optical fiber preform having an outer diameter of 180mm is drawn, it is found that the average value of concentricity is 0.6um, and the concentricity of partial optical fiber exceeds standard and reaches 0.7um at most, the drawing is stopped, the maximum error of the concentricity of the optical fiber is 0.7um, according to the calculation formula of the concentricity error of the finished rod, the concentricity error between the core rod and the finished rod in the corresponding 180mm preform is 1.008mm (finished rod concentricity error = optical fiber concentricity error X finished rod outer diameter ÷ optical fiber outer diameter), when the concentricity error is less than 0.6um, according to the concentricity error calculation formula of the finished bar, and the concentricity error of the corresponding finished rod is smaller than 0.864mm, the finished rod should be corroded from one side (1.008-0.864) × 2=0.288mm or more to ensure that the concentricity error of the optical fiber is within 0.6um, and the projection method is used for determining the side of the core rod deviated from the optical fiber preform, wherein the other side is the side needing acid pickling corrosion.
The optical fiber preform is horizontally placed in a pickling tank, one surface needing to be corroded faces downwards, hydrofluoric acid with the concentration of 30% is added, the liquid level of the acid just exceeds half of the height of the preform, a lifting platform is controlled to enable the platform to rise at a constant speed of 12.86mm/h, and pickling is finished after 7h of pickling. And (4) washing the residual acid liquor on the surface of the preform rod by using distilled water after the acid washing is finished, and drying the surface of the preform rod by using nitrogen or compressed air. And drawing the prefabricated rod, wherein the concentricity of the core and the cladding of the measured optical fiber after drawing is within the range of 0.1-0.2um and is far lower than the national standard requirement and less than 0.6 um.
In the invention, because the optical fiber preform rod changes in equal proportion in the drawing process, the distance between the points a and b can be changed by acid cleaning treatment before drawing to repair the preform rod with over-standard concentricity. The dotted line in fig. 1 is the boundary after acid cleaning, the thickness of the preform becomes smaller after acid cleaning, and the center point of the preform becomes b' from b after the thickness changes, so that the concentricity error of the optical fiber preform becomes smaller and reaches the national standard qualified range.
The invention relates to a method for restoring concentricity of an optical fiber preform, which is used for restoring the optical fiber preform with over-standard finished concentricity by pickling, changing the distance between the central point of a core layer and the central point of the finished optical fiber preform by pickling, and reducing the thickness of the over-standard side after pickling, so that the error of the concentricity of the optical fiber preform is reduced, the error of the concentricity of the finished optical fiber preform with over-standard finished optical fiber preform reaches the national standard range, the production qualification rate of the optical fiber is improved, the rejection of the preform is reduced, and the production cost is reduced.
The above examples only show some embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (9)
1. A method for restoring concentricity of an optical fiber preform is characterized by comprising the following steps:
step 1, horizontally placing an optical fiber preform with over-standard concentricity on a lifting platform in an acid tank, wherein one surface with over-standard concentricity faces downwards;
step 2, vertically moving the lifting platform downwards, and injecting acid liquor into the acid tank;
step 3, controlling the liquid level of the acid liquid to immerse half of the preform;
step 4, controlling the pickling time and the relative height of the prefabricated rod and the liquid level;
and 5, after pickling for a certain time, lifting the lifting platform or discharging acid in the acid tank, spraying the preform with distilled water, washing off residual acid liquor on the surface, and drying the surface of the preform with nitrogen or compressed air.
2. The method for restoring concentricity of an optical fiber preform according to claim 1, wherein the excessive concentricity is an error in concentricity of the optical fiber of more than 0.6 um.
3. The method for restoring concentricity of an optical fiber preform according to claim 1, wherein the acid solution in the step 2 is an acid solution of hydrofluoric acid.
4. The method for restoring concentricity of an optical fiber preform according to claim 1, wherein in steps 2 and 3, the lift platform is lowered to the bottom of the tank, and acid solution is injected to control the liquid level to immerse half of the preform; or injecting acid liquor into the acid tank in advance, and controlling the lifting platform to enable the preform to be half immersed.
5. The method for restoring concentricity of an optical fiber preform according to claim 1, wherein the acid washing time in the step 4 is determined based on the acid concentration and the immersion time.
6. The method for restoring concentricity of an optical fiber preform according to claim 1, wherein the relative height of the preform to the liquid level in step 4 is controlled such that the lift platform is slowly raised or the bath solution in the acid bath is slowly lowered when the liquid level is half of that of the preform.
7. The method for restoring concentricity of an optical fiber preform according to claim 1, wherein the excessively concentric optical fiber preform is washed by an acid to remove a thickness of 0 to 1mm from the excessively concentric optical fiber preform.
8. The method for restoring concentricity of an optical fiber preform according to claim 1, wherein a groove cover is provided in the acid groove, and a water spray hole is provided at one side in the acid groove.
9. The method for restoring concentricity of an optical fiber preform according to claim 1, wherein the optical fiber preform is a single mode or multimode optical fiber preform.
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| CN202010446134.1A CN111732335A (en) | 2020-05-25 | 2020-05-25 | Method for restoring concentricity of optical fiber preform |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101538113A (en) * | 2009-04-27 | 2009-09-23 | 中天科技精密材料有限公司 | Method for preparing a microgap sleeve optical fiber prefabrication bar and method for drawing and preparing an optical fiber by microgap sleeve optical fiber prefabrication bar |
| US20130327097A1 (en) * | 2012-06-08 | 2013-12-12 | Sumitomo Electric Industries, Ltd. | Method of manufacturing an optical fiber |
| CN106396360A (en) * | 2016-08-30 | 2017-02-15 | 武汉睿芯特种光纤有限责任公司 | Method for preparing gain fiber through online fusion shrinking and drawing |
| CN110954031A (en) * | 2019-12-24 | 2020-04-03 | 江苏法尔胜光子有限公司 | Method for detecting concentricity of core package of optical fiber preform |
| CN110981182A (en) * | 2019-12-11 | 2020-04-10 | 江苏通鼎光棒有限公司 | Optical fiber preform pickling equipment and pickling method thereof |
-
2020
- 2020-05-25 CN CN202010446134.1A patent/CN111732335A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101538113A (en) * | 2009-04-27 | 2009-09-23 | 中天科技精密材料有限公司 | Method for preparing a microgap sleeve optical fiber prefabrication bar and method for drawing and preparing an optical fiber by microgap sleeve optical fiber prefabrication bar |
| US20130327097A1 (en) * | 2012-06-08 | 2013-12-12 | Sumitomo Electric Industries, Ltd. | Method of manufacturing an optical fiber |
| CN106396360A (en) * | 2016-08-30 | 2017-02-15 | 武汉睿芯特种光纤有限责任公司 | Method for preparing gain fiber through online fusion shrinking and drawing |
| CN110981182A (en) * | 2019-12-11 | 2020-04-10 | 江苏通鼎光棒有限公司 | Optical fiber preform pickling equipment and pickling method thereof |
| CN110954031A (en) * | 2019-12-24 | 2020-04-03 | 江苏法尔胜光子有限公司 | Method for detecting concentricity of core package of optical fiber preform |
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