Background
The emergence of the optical fiber side-polishing technology enables evanescent fields in optical fibers to be more and more widely applied, and a plurality of optical fiber devices are developed on the basis of the evanescent fields. In one aspect, fiber side-cast techniques are widely applied in the fabrication of fiber optic sensors. When the optical fiber cladding is removed, the constraint of an internal optical field is weakened, the evanescent field starts to generate strong interaction with the outside, and then phenomena such as scattering, absorption, reflection and the like occur, and the environmental variable to be measured can be obtained by receiving and detecting through a proper method; or a method of coating or burying can be adopted, so that the side polished plane is directly contacted with metal or liquid, micro-nano scale optical phenomena such as surface plasma elements and the like are excited, and the variables of the external environment can be detected more sensitively. On the other hand, the side-polished optical fiber can also be used for preparing an optical fiber coupler with stable performance, and when two optical fibers are tightly attached through polished surfaces, a fiber core with a distance of a few microns can generate a good coupling effect through an evanescent field. In addition, the side-polished optical fiber can be used for preparing optical devices such as lasers, light modulators and the like.
In the last 80 th century, optical mode polarization selectors (R.A. bergh, H.C. Lefevre, H.J. Shaw, "Single-mode fiber-optical polarizer," Optics Letters, vol.5, No.11, pp.479-481,1980) were successfully prepared by manually stripping the cladding of the fiber together with the surface of the quartz block. The optical fiber side-polishing process is simple to operate and low in cost, but the side-polishing depth is not stable due to the fact that a depth control method is not adopted, a large amount of manual measurement is needed, the manufacturing period is long, the efficiency is low, the optical fiber is easy to break, and the yield is low.
After that, a silicon wafer with a V-shaped groove is used as a polishing carrier of the optical fiber instead of the conventional quartz block, and the optical fiber is fixed or removed by a releasable curing agent (s. -m.tseng, c. -l.chen "," Side poleshed fibers "," Applied Optics, vol.31, No.18, pp.3438-3447,1992). The method can effectively control the grinding depth, but does not solve the problems of fracture and time consumption caused by manual operation. In addition, for optical fibers with different outer diameters and polishing depth and length which are required to be different, different V-shaped groove silicon wafers need to be manufactured again, free adjustment and control of the polishing depth and the polishing length cannot be achieved, and relatively high cost is brought.
In order to solve the disadvantages of the manual polishing, a polishing technique using a polishing wheel along the longitudinal direction of the Optical fiber has been used and succeeded (M.H. Cordaro, D.L. Rode, T.S. Barry, R.R. Krchnavek, "Precision Fabrication of D-Shaped Single-Mode Optical Fibers by In Situ Monitoring," Journal of Lightwave Technology, vol.12, No.9, pp.1524-1531,1994). The method realizes more precise polishing depth control. However, because the polishing wheel and the optical fiber are in a fixed state and the optical fiber is always kept horizontal, the polishing surface of the method is circular with the same radius as that of the polishing wheel in the longitudinal cutting direction, and two parameters of the polishing depth and the polishing length cannot be independently controlled, so that controllable long-distance polishing cannot be realized.
In order to solve the problem of controllable polishing length, Harbin engineering university proposes a method of tightly attaching an optical fiber to a polishing wheel. The method ensures that the optical fiber is always tensioned by applying an external force, so that the optical fiber is bent and attached to the polishing wheel, and the effective length of the optical fiber attached to the polishing wheel is adjusted through the height of a triangle formed by the polishing wheel and the two ends of the optical fiber, so that the effective polishing length of the optical fiber is adjusted. However, this method is difficult to measure because the optical fiber is always in contact with the polishing roller, and therefore, the polishing depth can be measured only by a microscope when the polishing roller is separated from the optical fiber, and real-time measurement cannot be performed.
To enable real-time measurement of the fiber depth, Shenzhen university proposed a method of monitoring the polished depth of the fiber in real time using a broad spectrum light source and spectrometer (J.ZHao, G.yin, C.Liao, S.Liu, J.He, B.Sun, G.Wang, X.xu, Y.Wang, "Rough silicon-polarized fiber with surface diagnostics for sensing applications," IEEE Photonics Journal, 7.7, No.3, pp.0116807, 2015). The process can match the transmission spectrum information of the specific optical fiber under the specific polishing length and depth by using a characteristic identification method, thereby identifying whether the optical fiber reaches the specified polishing depth. However, such operations are not universal, since the spectral characteristics need to be measured for the structure, eigenmode, material, specified polishing depth and specified polishing length of the optical fiber, and thus, the method cannot be applied to a wider variety of optical fibers and more arbitrary polishing parameter settings, and further cannot obtain information about the quality of the polished plane of the optical fiber.
However, the existing method capable of freely regulating and controlling the side polishing parameters of the optical fiber is very limited by the type of the optical fiber and cannot freely regulate and control the side polishing parameters of the optical fiber, and the existing technology cannot observe the surface quality of the optical fiber under the condition of not dismantling equipment or taking out the optical fiber. In view of this, it is a problem that those skilled in the art need to solve to provide a device and a method that can freely regulate and control optical fiber side-polishing parameters, detect side-polishing optical fiber depth information in real time, and monitor the loss, polishing depth, polishing length, and polishing surface quality of the side-polishing optical fiber with full parameters.
Disclosure of Invention
The invention provides an optical fiber side polishing process device and method based on full-parameter monitoring, which solve the problem of real-time measurement of the polishing and grinding depth of an optical fiber, provide a solution for monitoring the full parameters of the side-polished optical fiber, and realize real-time/visual monitoring and regulation of the polishing and grinding depth, polishing and grinding length, polishing and grinding surface quality and the polishing and grinding rotation direction of the optical fiber.
The invention provides a full-parameter monitoring optical fiber side-polishing process device on one hand, which comprises the following steps: the device comprises an optical fiber polishing wheel, a displacement measurement module, a vertical fixed base plate, a fixed pulley, two optical fiber clamps symmetrically arranged on two sides of the optical fiber polishing wheel, two axial elastic connecting seats, two horizontal displacement platforms, a side micro-camera, a vertical micro-camera, a light source, an optical power meter and a vertical displacement platform.
The optical fiber polishing wheel and the main body part of the displacement measurement module are fixed on the vertical fixed substrate and are always kept relatively static. The optical fiber penetrates through the optical fiber polishing wheel and is partially bent and attached to the optical fiber polishing wheel, the back side of the optical fiber is always attached to the measuring end of the closely attached precision displacement measuring module through micro elasticity, and the lateral polishing depth of the optical fiber is measured in real time under the condition that the polishing quality of the optical fiber is not influenced. The vertical fixing substrate is fixed on the vertical displacement platform and used for regulating and controlling the length of the optical fiber attached to the optical fiber polishing and grinding wheel so as to regulate the side polishing length. The optical fiber is bent to be in a horizontal state through the fixed pulley, two ends of the optical fiber are fixed through the rotatable optical fiber holder, and the optical fiber holder has the function of rotating around the shaft for 360 degrees and is used for controlling a side polishing area around the shaft. The optical fiber holders at the two ends are fixed on the horizontal displacement platform through the axial elastic connecting seats, and because the axial elastic connecting seats can provide adjustable tension to the two sides, the tension state of the optical fiber in the polishing, grinding and moving processes is kept. A side micro-camera and a vertical micro-camera are arranged between the fixed pulley and the optical fiber holder on one side, and when the side polishing area of the optical fiber is translated to the position of the micro-camera, the side micro-camera and the vertical micro-camera are used for visually detecting the polishing depth, polishing length and surface quality of the side polished optical fiber. And the two ends of the optical fiber are connected with the light source and the optical power meter and used for measuring the loss of the side-polished optical fiber. Therefore, the device can control the side polishing area around the shaft direction and adjust the side polishing length, and can carry out full-parameter monitoring on the optical fiber side polishing process, and the method comprises the following steps: polishing depth, polishing length, polishing surface quality and loss.
Preferably, the displacement measurement module has submicron-level measurement accuracy and comprises a module main body and a measurement end, wherein the module main body is fixed with the vertical fixing substrate and keeps relatively static with the polishing roller, the measurement end is kept attached to the back side of the optical fiber through a micro-elastic effect, the micro-elastic attachment does not affect the polishing quality of the optical fiber, and meanwhile polishing depth information in the optical fiber side polishing process can be acquired in real time. The displacement measuring module can be an optical sensing device such as a precision displacement interferometer or a mechanical precision displacement measuring instrument such as a micrometer.
Preferably, the axial elastic connecting seats, the optical fiber holder and the horizontal displacement platform on two sides are positioned on the same fixed plane. In the horizontal movement, the horizontal displacement platforms on the left side and the right side can keep synchronous movement, so that the polishing performance can be monitored by translating the optical fiber side polishing area to the position of the microscope camera in the optical fiber polishing process, and the optical fiber side polishing area can be reset to the position of the optical fiber polishing wheel to continue polishing after monitoring.
Preferably, the relative position of the optical fiber polishing wheel and the optical fiber can be reversed by 180 degrees in the vertical direction, the optical fiber is changed from the upper part of the original optical fiber polishing wheel to the upper part of the optical fiber, at the moment, the corresponding displacement measurement module is also adjusted to be above the optical fiber and is kept jointed with the back side of the optical fiber side polishing area through micro elasticity, and the corresponding vertical phase camera is also positioned below the optical fiber.
Preferably, the material of the optical fiber polishing wheel is not exclusive, and the optical fiber polishing wheel can be an integrated polishing wheel of metal with a frosted surface or other hard materials, and can also be a combined polishing wheel formed by combining a common roller and grinding paper. The optical fiber polishing and grinding wheel has various surface roughness degrees which can be selected, the rough surface is used for regulating and controlling the grinding depth, and the fine surface is used for polishing the optical fiber side polishing surface, namely the polishing type polishing and grinding wheel. And the size of the optical fiber polishing wheel can be switched, or a plurality of optical fiber polishing wheels with different sizes or different surface roughness degrees can be assembled on the vertical fixed substrate, so that flexible selection and replacement are facilitated, and the side polishing length can be adjusted by controlling the joint degree of the optical fiber polishing wheel and the optical fiber.
Preferably, the side-polished fiber can be various fibers such as a single-mode fiber, a few-mode fiber, a multi-mode fiber, a special fiber and the like.
The invention also provides a full-parameter monitoring side-polishing process method based on the device, which comprises the following steps:
step 1, a presetting stage. Before polishing, the height of the optical fiber polishing wheel needs to be preset, so that the contact length of the optical fiber and the optical fiber polishing wheel is adjusted, and the polishing length of the optical fiber is adjusted. Secondly, the optical fiber rotates around the shaft through the rotatable optical fiber holder and is fixed on the axial elastic connecting seat so as to obtain the tension for tensioning the optical fiber without breaking. The part of the optical fiber to be polished is positioned between the optical fiber polishing wheel and the precision displacement measurement module closely attached to the optical fiber, and two ends of the optical fiber are respectively connected with the light source and the optical power meter.
And 2, polishing and grinding. In the polishing and grinding process, the wheel shaft of the optical fiber polishing and grinding wheel and the main body part of the precision displacement measurement module closely jointed with the optical fiber are always kept relatively still, and the measurement end of the precision displacement measurement module closely jointed with the optical fiber is always kept jointed with the back side of the polishing and grinding area of the optical fiber through micro-elasticity, so that the polishing and grinding depth of the optical fiber is monitored in real time. Meanwhile, the loss of the side-polished optical fiber is monitored in real time through a light source and an optical power meter. And then, the optical fiber polishing area is smoothly moved to an observation area where the side micro-camera and the vertical micro-camera are located through the horizontal displacement platform, and the optical fiber is in a horizontal tensioning state, so that the visual, intuitive and fine measurement of the polishing depth, polishing length and polishing surface quality of the optical fiber can be completed. And when the polishing depth and the polishing length preliminarily meet the standards, the next step can be carried out. Otherwise, polishing and grinding are continued.
And 3, polishing. The optical fiber polishing wheel is replaced by a polishing type polishing wheel with lower roughness, the optical fiber polishing area is smoothly moved back to the polishing area through the horizontal displacement platform, polishing and grinding are repeated, the surface quality of the optical fiber is observed for multiple times, and the side polishing quality meets the requirement. And simultaneously measuring the loss of the side-polished optical fiber. And finally, taking out the side-polished optical fiber.
Through the technical scheme, compared with the prior art, the invention has the following beneficial effects:
(1) the invention realizes the free adjustment and control of polishing length, polishing rotation direction and the like in the optical fiber side polishing process, and improves the flexibility and controllability of the optical fiber side polishing process.
(2) The invention realizes the online real-time accurate measurement of polishing and grinding depth parameters which are very important in the optical fiber side polishing process, which is a technology which is difficult to realize in the conventional optical fiber side polishing process.
(3) The invention realizes the simultaneous monitoring of the whole parameters of the optical fiber side-polishing process, not only can accurately measure the polishing depth in real time on line, but also can visually monitor the polishing depth, the polishing length and the polishing surface quality, and can also detect the loss of the side-polishing optical fiber, thereby monitoring the quality of the optical fiber side-polishing process in all directions, comprehensively mastering the preparation success rate and various performance parameters of the side-polishing optical fiber, and fully ensuring the preparation of the high-quality side-polishing optical fiber meeting various application requirements, which is not possessed by the conventional optical fiber side-polishing process.
(4) The invention realizes the rough polishing of polishing depth control and the fine polishing of polishing quality control of the optical fiber side polishing process.
(5) The invention realizes the optical fiber side-polishing process which can be compatible with various optical fibers, including various optical fibers such as single-mode optical fibers, few-mode optical fibers, multi-mode optical fibers, special optical fibers and the like, is not limited by the size, the internal structure and the material of the optical fibers, and can be widely applied to the fields of optical fiber communication, sensing measurement and the like.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The following description is made with reference to the embodiments and the accompanying drawings.
As shown in fig. 1, the optical fiber side polishing process apparatus for full parameter monitoring provided by the present invention includes an optical fiber polishing wheel 1, a displacement measurement module 2, a vertical fixing substrate 3, a fixed pulley 4, an optical fiber holder 5, an axial elastic block 6, a side micro-camera 7, a vertical micro-camera 8, a light source 9, an optical power meter 10, a horizontal displacement platform 11, and a vertical displacement platform 12.
Specifically, as shown in fig. 2, in the pre-adjusting stage, firstly, the height of the optical fiber polishing wheel needs to be pre-adjusted, so as to adjust the contact length between the optical fiber and the optical fiber polishing wheel, and thus adjust the polishing length of the side-polished optical fiber. Secondly, the optical fiber rotates around the shaft through the rotatable optical fiber holder and is fixed on the axial elastic connecting seat so as to obtain the tension for tensioning the optical fiber without breaking. The part of the optical fiber to be polished is positioned between the optical fiber polishing wheel and the precision displacement measurement module closely attached to the optical fiber, and two ends of the optical fiber are respectively connected with the light source and the optical power meter.
In the polishing and grinding stage, the wheel shaft of the optical fiber polishing and grinding wheel and the main body part of the displacement measurement module are always kept relatively still, and the measurement end of the precision displacement measurement module with closely jointed optical fibers is always jointed with the back side of the optical fiber polishing and grinding area through micro-elasticity, so that the polishing and grinding depth of the optical fibers is monitored in real time. Meanwhile, the loss of the side-polished optical fiber is monitored in real time through a light source and an optical power meter. And then, the optical fiber polishing area is smoothly moved to an observation area where the side micro-camera and the vertical micro-camera are located through the horizontal displacement platform, and the optical fiber is in a horizontal tensioning state, so that the visual, intuitive and fine measurement of the polishing depth, polishing length and polishing surface quality of the optical fiber can be completed. And when the polishing depth and the polishing length preliminarily meet the standards, the next step can be carried out. Otherwise, polishing and grinding are continued.
In the polishing stage, the optical fiber polishing wheel is replaced by a polishing type polishing wheel with lower roughness, the optical fiber polishing area is smoothly moved back to the polishing area through the horizontal displacement platform, the polishing and the grinding are repeated, the surface quality of the optical fiber is observed for multiple times, and the side polishing quality meets the requirement. And simultaneously measuring the loss of the side-polished optical fiber. And finally, taking out the side-polished optical fiber.
As shown in fig. 3, the precision displacement measurement module with closely attached optical fibers provided by the invention is used for measuring the polishing depth of the side-polished optical fibers in real time. The method comprises the following steps: the device comprises a polishing wheel fixing shaft 15, a polishing wheel 1, a vertical base plate 3, a precision displacement measuring instrument moving end 21, a precision displacement measuring instrument fixing end 22, a rigid horizontal plate 23, a first spring 20, a movable plate 16, a second spring 17, a fixed plate 18 and a horizontal adjusting screw 19 which are symmetrically arranged at two sides of the precision displacement measuring instrument.
Specifically, the two fixing plates 18 are fixing parts on the vertical base plate 3. The two movable plates 16 are fixed with the fixed plate 18 through the second spring 17 and the horizontal adjusting screw 19 connected with the two movable plates, and the height of the movable plates 16 can be adjusted through adjusting the horizontal adjusting screws 19 at the two sides. The rigid horizontal plate 23 is fixed to the movable plates 16 on both sides by two symmetrically placed first springs 20. The first springs 20 on both sides are micro-elastic springs, and the function of the springs is to make the rigid horizontal plate 23 always keep fit with the optical fiber 14 and not to break the optical fiber 14 due to excessive force. Wherein, the two side movable plates 16 can ensure that the rigid horizontal plate 23 is kept horizontal in the fitting process by adjusting the height.
Specifically, the fixed end 21 of the precision displacement measuring instrument is fixed on the vertical substrate 3 by a screw or a pressing plate, and does not displace along with polishing movement. The moving end 22 of the precision displacement measuring instrument is fixedly attached to the other side of the rigid horizontal plate 23, so that the precision displacement measuring instrument can accurately record the polishing and grinding depth of the optical fiber.
As shown in fig. 4, the present invention is an alternative of the optical fiber side polishing process apparatus for full parameter monitoring, which includes an optical fiber polishing wheel 1, a precision displacement measurement module 2 with closely attached optical fibers, a vertical fixed substrate 3, a fixed pulley and its fixed mount 4, a rotatable optical fiber holder 5, an axial elastic block 6, a side micro-camera 7, a vertical micro-camera 8, a light source 9, an optical power meter 10, a horizontal displacement platform 11, and a vertical displacement platform 12. Under the device, an optical fiber polishing wheel 1 is positioned at the lower side of an optical fiber, a precision displacement measurement module 2 which is closely attached to the optical fiber is positioned at the upper side of the optical fiber, a vertical microscopic camera 8 is positioned at the lower side of the optical fiber, and the rest parts are kept the same as those in the figure 1.
It should be understood that the above description is only one specific embodiment of the present invention, and is not intended to limit the present invention, and any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.