CN103309002A - Capillary sensitivity enhancing packaging device capable of applying prestress to fiber grating - Google Patents

Abstract

The invention discloses a device capable of applying prestress on a fiber grating and packaging the fiber grating in a capillary sensitivity enhancing manner. The device is structurally characterized in that a dovetail guide rail is arranged on a base, a left slider, a right slider and a middle slider are arranged on the dovetail guide rail, a left fine adjustment translation stage is arranged on the left slider, a right fine adjustment translation stage is arranged on the right slider, a left clamping gasket is arranged on the left fine adjustment translation stage, a right clamping gasket is arranged on the right fine adjustment translation stage, powerful magnets, the left clamping gasket and the right clamping gasket are matched with one another to generate magnetic force, a lifting rod sleeve is arranged on the middle slider, a lifting rod which is connected with an object stage is arranged on the lifting rod sleeve, and a pair of capillary fixing clips is arranged on the object stage. The device can guarantee that the fiber grating is effectively axially centered in a capillary; a capillary packaging process for the fiber grating can be simplified; the magnitude of the prestress can be continuously controlled. The device has the advantages of simple structure, easiness in operation and the like. Besides, after the device is used packaging the fiber grating in a capillary manner, a phenomenon of chirp and a phenomenon of waveform distortion can be effectively prevented, and the repeatability and the linearity of a sensor are guaranteed.

Description

A Capillary Sensitization Encapsulation Device That Can Apply Prestress to Fiber Bragg Grating

technical field

The invention relates to a capillary type sensitivity-increasing packaging device capable of applying prestress to an optical fiber grating.

Background technique

Since 1989, when G. Meltz and others of United Technology Center in the United States succeeded in fabricating fiber gratings by holographic interferometry, a lot of research has been done on optical fiber manufacturing technology and demodulation technology at home and abroad. Especially in recent years, fiber gratings have developed rapidly in sensing technology and other fields, and have broad application prospects. The fiber grating sensor is based on the center wavelength shift of the grating reflection spectrum or transmission spectrum caused by the measured physical quantity. The measurement of the physical quantity to be measured can be realized by detecting the wavelength shift. It is a wavelength modulation sensor with strong anti-electromagnetic interference ability and small size. , light weight, simple structure, easy to reuse and many other advantages, can form an intelligent distributed sensor network. When the bare grating is buried inside the measured material, it can realize multi-point distribution, simultaneous distinction, real-time online and long-term monitoring of many physical quantities such as temperature, stress, strain, and pressure. However, the temperature and strain sensitivity of the bare grating is low, which cannot meet the sensing requirements, so it is necessary to try to improve the temperature and strain sensitivity. At the same time, since the fiber grating is written on the single-mode silica fiber with the coating removed by ultraviolet light, it is small, brittle, and easy to break; although the chemical properties of the silica fiber are relatively stable, its resistance to acid and alkali is relatively low. Difference. In order to improve the adaptability of the fiber grating in the harsh environment of practical application, it also needs to be effectively packaged and protected.

The central wavelength of the fiber grating packaged in the sensitization package is very sensitive to changes in external environmental variables (temperature, strain, stress, etc.). However, if the packaging structure of the fiber grating is unstable during the packaging process, the force field on the fiber grating may be unstable, and there will be a cross-sensitive effect of temperature and strain, resulting in inaccurate temperature sensing. Therefore, in order to eliminate the influence of the unstable force field on the central wavelength of the fiber grating, the stability of the packaging structure must be ensured when designing the packaging device structure.

When the fiber grating is not prestressed, it is in a relatively free state, and there will be a certain bending, and the bending direction is uncertain, which leads to an unstable relationship between the fiber grating and the capillary zinc tube. If encapsulation methods such as polymer curing paste are used, shrinkage will occur due to the polymer curing process. If a certain prestress is not applied to the fiber grating, the fiber grating after packaging is prone to chirp phenomenon; even if there is no chirp phenomenon after packaging, it will drive the fiber grating axially to Shrinkage produces a chirp phenomenon, which greatly reduces the stability and repeatability of the sensor, and also brings difficulties to demodulation. If a packaging device that can apply prestress is used, prestressing the fiber grating during the packaging process can ensure a stable relationship between the fiber grating and the capillary zinc tube, and at the same time prevent it from shrinking as the polymer solidifies and shrinks, avoiding chirp. Chirp phenomenon, which is conducive to the stability and good repeatability of the wavelength temperature characteristics.

The existing Chinese 03132410.X discloses a fiber grating capillary packaging process and a special device, which specifically includes a base, a vertical support is installed on the base, a horizontal bar is installed on the vertical support, and a capillary fixing clip is installed at the end of the horizontal bar. An adjustable metal sheet is arranged on the upper end of the vertical support, and a groove is opened on the adjustable metal sheet, and a fastening rubber matched with the Cao is provided, and it also includes a vacuum device connected to the lower end of the capillary. The device provides a simple and compact fiber grating capillary packaging solution, which has the following disadvantages: during the packaging process, prestress cannot be applied to the fiber grating, and the fiber grating cannot be adjusted to precisely coincide with the axis of the capillary; the packaging Finally, fiber gratings are prone to chirp and wavelength distortion.

The existing Chinese patent 200810150477.2 discloses a packaging device for applying prestress to a fiber grating sensor, which specifically includes a left mounting seat connected to the left mobile station, a right mounting seat connected to the mobile station, a left mounting seat and A platform elevating rod cover is arranged between the right mounting seats, a left elevating rod cover is arranged on the left moving platform, a right elevating rod cover is arranged on the right moving platform, and a translation conversion mechanism is also arranged on the left moving platform and the right moving platform. The left elevating rod whose top end is connected with the left clamping frame is arranged on the rod sleeve. The right lifting rod that the top is connected with the right clamping frame is arranged on the right lifting rod cover, and the platform lifting rod whose upper end is connected with the platform is set on the platform lifting rod cover. Wherein said right clamping frame structure is: the bottom of the bracket is arranged on the upper end of the right elevating rod, the front and rear sides of the bracket are respectively provided with adjusting screw rods connected with the clamping plates, and the inner surfaces of the two clamping plates are provided with elastic gaskets. The installation of the left clamping frame is similar to it, and has the same structure as the right clamping frame. The device provides a packaging solution with a simple structure, a small footprint, and the ability to effectively apply prestress to the fiber grating. Its disadvantages include: limited applicable packaging methods, such as tube packaging without a fixed capillary mechanism; The horizontal direction of the workbench is fixed, which cannot meet the mobile requirements of some packaging methods.

Contents of the invention

The object of the present invention is to provide a capillary type sensitization package device capable of applying prestress to the fiber grating, which has the advantages of compact structure, simple operation and precise control.

The present invention is realized in this way, it includes base, dovetail guide rail, left slider, left fine-tuning translation platform, left clamping spacer, elastic rubber layer I, elastic rubber layer II, left strong magnet, fiber grating, capillary zinc tube , right strong magnet, elastic rubber layer III, elastic rubber layer IV, right clamping spacer, right fine-tuning translation stage, right slider, stage, right capillary clamp, lifting rod cover, adjusting fixture, lifting rod, The middle slider and the left capillary clamp are characterized in that the upper part of the base is connected with a dovetail guide rail, the middle slider is connected to the middle part of the dovetail guide rail, the left slider and the right slider are symmetrical about the middle slider, and are respectively connected to the dovetail guide rail On both sides, the upper part of the left slider is connected with the left fine-tuning translation platform, the upper part of the left fine-tuning translation platform is the left clamping gasket, and the upper surface of the left clamping gasket is provided with elastic rubber layer I, which is close to the The elastic rubber layer II on the lower surface of the left powerful magnet, the upper part of the right slider is connected with the right fine-tuning translation platform, the upper part of the right fine-tuning translation platform is the right clamping gasket, and the upper surface of the right clamping gasket is provided with elastic rubber layer III , the elastic rubber layer III is closely attached to the elastic rubber layer IV located on the lower surface of the right powerful magnet, the lifting rod cover is connected to the upper part of the middle slider, the lower part of the lifting rod is connected to the lifting rod cover through the adjusting fixture, and the upper end of the lifting rod is connected to the load An object stage, a capillary zinc tube is arranged on the object stage, an optical fiber grating is arranged in the capillary zinc tube, and the capillary zinc tube is fixed on the object stage by the right capillary tube fixing clip and the left capillary tube fixing clip;

The bottoms of the left slider, the right slider and the middle slider are all provided with dovetail grooves, and the sides of the left slider, the right slider and the middle slider are all provided with limit screws; The structural dimensions of the fine-tuning translation stages are exactly the same and distributed vertically. The dovetail grooves at the bottom of the left slider, right slider and middle slider can move on the dovetail guide rail to realize precise control of the slider position; the axial rotation of the slider is limited by the dovetail groove engaging with the dovetail boss;

There are limit screws on the side of the slider, through which the axial movement of the slider is limited, so that the slider is fixed on the guide rail. The structural dimensions of the left fine-tuning translation stage and the right fine-tuning translation stage are exactly the same, and they are installed in a vertical distribution. The left fine-tuning translation stage realizes axial adjustment, and the right fine-tuning translation stage realizes lateral adjustment;

The left fine-tuning translation table has threaded holes, and the left clamping gasket is fixed on the left fine-tuning translation table through countersunk head screws. The length and width of the two are the same, and the heights are different; The screws are fixed on the right fine-tuning translation platform, both of which have the same length and width, but different heights; the length, width and height of the left clamping spacer and the right clamping spacer are the same;

The left clamping spacer and the right clamping spacer are made of ferromagnetic material, which can generate magnetic force with the magnet to realize the clamping of the fiber grating. Various mounting holes are opened on the stage, and the left capillary clamp and the right capillary clamp are composed of Bolts are fixed on the stage, and the capillary clamp can be disassembled or installed with other clamping devices for other packaging methods as required.

The technical effects of the present invention are: the present invention adopts the magnetic force generated between the magnet and the ferritic stainless steel, and uses elastic rubber to clamp the optical fiber grating, which is easy to operate and highly repeatable; the elastic rubber used is perfluoroether rubber, which High temperature resistance (327°C), chemical solvent resistance and high cleanliness, suitable for a wide range of operating temperatures, can be used in the temperature range of 0°C~327°C; can ensure that the fiber grating is well aligned with the axis in the capillary; can Simplify the fiber grating capillary packaging process; can realize high-temperature curing packaging under the condition of prestressing the fiber grating, can realize continuous control of external force, continuous adjustment of prestress; has the advantages of simple structure, small size, easy operation, and low cost. Using the invention to encapsulate the fiber grating in capillary type can effectively prevent chirp phenomenon and waveform distortion phenomenon, and ensure the repeatability and linearity of the sensor.

Description of drawings

Fig. 1 is a structural schematic diagram of an embodiment of the present invention.

Fig. 2 is a partial top view of the structure of the present invention.

Fig. 3 is a schematic diagram of the displacement adjustment of the present invention.

In the figure, 1. Base 2. Dovetail guide rail 3. Left slider 4. Left fine-tuning translation platform 5. Left clamping spacer 6. Elastic rubber layer Ⅰ 7. Elastic rubber layer Ⅱ 8. Left strong magnet 9. Optical fiber grating 10. Capillary zinc tube 11. Right strong magnet 12. Elastic rubber layer III 13. Elastic rubber layer IV 14. Right clamping spacer 15. Right fine-tuning translation platform 16. Right slider 17. Stage 18. Right capillary fixation Clamp 19, Lifting Rod Cover 20, Adjusting Fixing Part 21, Lifting Rod 22, Middle Slider 23, Left Capillary Fixing Clip.

Detailed ways

As shown in Fig. 1 and Fig. 2, the present invention is realized in this way, it comprises base 1, dovetail guide rail 2, left slider 3, left fine-tuning translation table 4, left clamping spacer 5, elastic rubber layer I6, elastic Rubber layer Ⅱ7, left powerful magnet 8, fiber grating 9, capillary zinc tube 10, right powerful magnet 11, elastic rubber layer Ⅲ12, elastic rubber layer Ⅳ13, right clamping spacer 14, right fine-tuning translation platform 15, right slider 16 , stage 17, right capillary clamp 18, lifting rod cover 19, adjustment fixture 20, lifting rod 21, middle slider 22 and left capillary fixing clamp 23, its structural feature is that the top of base 1 is connected with dovetail guide rail 2 , the middle slider 22 is connected to the middle of the dovetail guide rail 2, the left slider 3 and the right slider 16 are symmetrical about the middle slider 22, and are respectively connected to both sides of the dovetail guide rail 2, and the upper part of the left slider 3 and the left fine-tuning translation The platform 4 is connected, the upper part of the left fine-tuning translation platform 4 is the left clamping spacer 5, the upper surface of the left clamping spacer 5 is provided with an elastic rubber layer I6, and the elastic rubber layer I6 is close to the elastic body located on the lower surface of the left powerful magnet 8. Rubber layer II7, the upper part of the right slider 16 is connected with the right fine-tuning translation platform 15, the upper part of the right fine-tuning translation platform 15 is the right clamping pad 14, and the upper surface of the right clamping pad 14 is provided with an elastic rubber layer III12, elastic The rubber layer III12 is close to the elastic rubber layer IV13 located on the lower surface of the right powerful magnet 11. The lifting rod cover 19 is connected to the upper part of the middle slider 22, and the lower part of the lifting rod 21 is connected to the lifting rod cover 19 through the adjustment fixing part 20. The lifting rod The upper end of 21 connects stage 17, and stage 17 is provided with capillary zinc tube 10, and capillary zinc tube 10 is provided with fiber grating 9, and capillary zinc tube 10 is fixed on by right capillary tube fixing clip 18 and left capillary tube fixing clip 23. On the stage 17;

When installing and using, the installation position of the dovetail guide rail 2 is a dovetail boss with a scale, and the left slider 3, the right slider 16 and the middle slider 22 with a dovetail groove are installed through the dovetail boss. The middle slider 22 is threaded to fix the lifting rod cover 19, and the lifting rod 21 is arranged in the lifting rod cover 19 to adjust the height of the stage 17, which is beneficial to the axis alignment of the optical fiber grating 9 and the capillary zinc tube 10, and the lifting rod 21 Fix the stage 17 on the top, and a pair of right capillary fixing clips 18 and left capillary fixing clips 23 are installed on the stage 17 for fixing the capillary zinc tube 10 . The structure of the left slider 3 and the right slider 16 is exactly the same, but the installation directions are different, and the two are vertically distributed. The installation of this positional relationship can realize two-dimensional plane adjustment and reduce the cost of the device. On the left and right sliders, the left fine-tuning translation platform 4 and the right fine-tuning translation platform 15 are installed through threaded connections, and the left micro-adjustment translation platform 4 is fixed with a left clamping spacer 5 through threaded connections, and the left fine-tuning translation platform 4 is fixed through threaded connections There is a right clamping spacer 14, on the spacer, there is an elastic rubber layer with 502 glue, and it is the left strong magnet 8 and the left strong magnet 11 that cooperate with ferritic stainless steel to generate magnetic force, and the magnet lower surface is also cushioned with an elastic rubber layer. When packaging, the first step is to clamp both ends of the fiber grating 10 on the left and right sliders through magnets, and put the grating part into the capillary zinc tube 10, and the capillary zinc tube 10 is fixed on the left and right capillary tubes of the stage 17. On the fixing clip; the second step is to roughly adjust the sliders at both ends to check whether the fiber grating is parallel to the axis of the guide rail. If it is not parallel, adjust the right fine-tuning translation table to make it parallel; Align the tube axis, if not, adjust the lifting rod to align with the capillary zinc tube axis; the fourth step, calculate the displacement according to the required prestress, and adjust the left fine-tuning translation platform to make the FBG in the predetermined tensile stress state; The fifth step is to use the modified acrylate to glue the two ends of the capillary zinc tube, and the grating in the tube is not filled with the modified acrylate in a suspended state; the sixth step is to allow the modified acrylate to condense and solidify naturally, until the modified acrylate is completely Curing completes the entire encapsulation process.

,代入参数得 As shown in Figure 3, prestress is applied; the method of calculating the prestress is that E ₁ and E ₂ are the elastic modulus of the grating and clad fiber respectively, and r ₁ and r ₂ are the radii of the grating and clad fiber respectively . The displacement adjustment process is shown in Figure 1. The adjustment displacement DL of the translation stage is fine-tuned. At this time, the elongation of the grating is DL ₁ . The length L of the fiber grating between the left and right fine-tuning translation stages is L ₁ . Since the axial tension of the grating and the clad fiber is equal, that is,

, substituting the parameter to get

,                                                             (2-1)

, (2-1)

also because , (2-2)

Combine (2-1) and (2-2) to get

                                (2-3)

(2-3)

Then the prestress calculation formula is

               (2-4) 

(2-4)

为常数，则预应力

与DL呈线性关系。 in

is a constant, the prestress

There is a linear relationship with DL .

Claims (3)

1. one kind can apply prestressed capillary type enhanced sensitivity packaging system to fiber grating, it comprises base, dovetail guide, left slider, left fine setting translation stage, left holding shim, the elastic rubber layer I, the elastic rubber layer II, powerful Left magnet, fiber grating, the capillary zinc pipe, right strong magnets, the elastic rubber layer III, the elastic rubber layer IV, right holding shim, right fine setting translation stage, right slide block, objective table, right kapillary geometrical clamp, the elevating lever cover, regulate fixture, elevating lever, intermediate slider and left kapillary geometrical clamp, the top that it is characterized in that base is connected with dovetail guide, intermediate slider is connected to the middle part of dovetail guide, left slider and right slide block are symmetrical about intermediate slider, and be connected to the both sides of dovetail guide, the top of left slider links to each other with left fine setting translation stage, the top of left fine setting translation stage is left holding shim, the upper surface of left holding shim is provided with the elastic rubber layer I, the elastic rubber layer I is close to the elastic rubber layer II that is positioned at powerful Left magnet lower surface, the top of right slide block links to each other with right fine setting translation stage, the top of right fine setting translation stage is right holding shim, the upper surface of right holding shim is provided with the elastic rubber layer III, the elastic rubber layer III is close to the elastic rubber layer IV that is positioned at right strong magnets lower surface, the elevating lever cover is connected to intermediate slider top, the bottom of elevating lever is connected in the elevating lever cover by regulating fixture, the upper end of elevating lever connects objective table, objective table is provided with the capillary zinc pipe, be provided with fiber grating in the capillary zinc pipe, the capillary zinc pipe is fixed on the objective table by right kapillary geometrical clamp and left kapillary geometrical clamp.

2. as claimed in claim 1ly a kind ofly can apply prestressed capillary type enhanced sensitivity packaging system to fiber grating, it is characterized in that described left slider, right slide block and intermediate slider bottom all have dovetail groove, the sidepiece of left slider, right slide block and intermediate slider is equipped with stop screw.

3. as claimed in claim 1ly a kind ofly can apply prestressed capillary type enhanced sensitivity packaging system to fiber grating, it is characterized in that the physical dimension of described left fine setting translation stage and right fine setting translation stage is identical, and be in vertical distribution.

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