A spherical end-face fluorescent fiber structure and its fabrication method

Abstract

This invention relates to fluorescent fiber structures, specifically to a spherical end-face fluorescent fiber structure and its fabrication method. It addresses the shortcomings of existing flat-end-face fluorescent fiber structures, such as complex manufacturing processes, low yield rates, unsuitability for high-electric-field environments, and the irreversible carbonization and yellowing of the high-temperature resistant optical adhesives used, which hinder fluorescence transmission through the temperature-sensing layer at excessively high temperatures. The spherical end-face fluorescent fiber structure includes a fluorescent fiber with a hemispherical end. It also includes a temperature-sensing structure disposed on the spherical surface of the hemispherical structure. The temperature-sensing structure comprises a temperature-sensing layer connected to the spherical surface of the hemispherical structure and a reinforcing layer disposed outside the temperature-sensing layer. The temperature-sensing layer is a mixture of silica and a fluorescent material, and the reinforcing layer is a high-temperature resistant epoxy resin adhesive. Furthermore, this invention also provides a method for fabricating the spherical end-face fluorescent fiber.

Description

Technical Field

[0001] This invention relates to fluorescent fiber structures, specifically to a spherical end-face fluorescent fiber structure and its fabrication method. Background Technology

[0002] Fluorescent fiber optic thermometry is based on the material properties of rare-earth fluorescent materials. When certain special rare-earth sensitive materials are excited by light, they emit a visible linear spectrum, i.e., fluorescence. After the excitation light disappears, the fluorescence typically decays exponentially. The time constant of exponential decay is called the fluorescence lifetime. The fluorescence lifetime is monotonic with temperature, and temperature can be measured using the fluorescence lifetime. Fluorescent fiber optic thermometry requires a stable excitation source and an information channel. Therefore, under quantitative excitation, the structure of the fiber end face plays a decisive role in maximizing the excitation of optical signals.

[0003] The probe part of the existing fluorescent fiber adopts a flat end face structure prepared by grinding process. Its temperature measuring structure is a mixture of phosphor powder and high temperature resistant optical adhesive placed on the flat end face structure. During preparation, the liquid mixture is first applied to the flat end face structure and then cured by high temperature. The existing flat end face fluorescent fiber structure has the following shortcomings: (1) The process is complicated, the processing time is long, and it is difficult for workers to master. Each grinding requires different grinding paper. After four grindings, the grinding pressure adjustment needs to be based on usual experience, which cannot be standardized. (2) The fiber end face has a low pass rate, long processing time, low work efficiency, and requires a lot of consumables, which wastes resources. (3) The produced fiber end face is flat and sharp. It has a high probability of discharge in a high electric field environment, so it is not suitable for high electric field environment. (4) The high temperature resistant optical adhesive will undergo irreversible carbonization and yellowing at excessively high temperatures, which will block the transmission of fluorescence by the temperature measuring layer, thus affecting the temperature measuring signal. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing flat-end fluorescent fiber structures, such as complex manufacturing processes, low yield rates, unsuitability for high electric field environments, and the irreversible carbonization and yellowing of the high-temperature resistant optical adhesives used, which hinder the transmission of fluorescence by the temperature sensing layer. The invention provides a spherical end-face fluorescent fiber structure and its preparation method.

[0005] To address the shortcomings of the existing technology, the present invention provides the following technical solution:

[0006] A spherical end-face fluorescent fiber structure includes a fluorescent fiber, one end of which is a hemispherical structure. The structure is characterized by further including a temperature-sensing structure disposed on the spherical surface of the hemispherical structure. The temperature-sensing structure includes a temperature-sensing layer connected to the spherical surface of the hemispherical structure and a reinforcing layer disposed outside the temperature-sensing layer. The temperature-sensing layer is a mixture of silica and a fluorescent substance, and the reinforcing layer is a high-temperature resistant epoxy resin adhesive.

[0007] Furthermore, the hemispherical structure is a resin hemispherical lens.

[0008] Furthermore, the hemispherical structure is a hemispherical optical fiber that is fused together.

[0009] Furthermore, the temperature measuring structure is adhered to the spherical surface of the hemispherical structure and fixed by thermosetting.

[0010] Furthermore, the silicon dioxide is silicon dioxide powder, the fluorescent material is fluorescent powder, and the mass ratio between the silicon dioxide and the fluorescent material is 1:4 to 6.

[0011] Meanwhile, the present invention also provides a method for fabricating a spherical end-face fluorescent fiber, which is characterized by comprising the following steps based on the above-mentioned spherical end-face fluorescent fiber structure:

[0012] Step (1): Mix silicon dioxide and fluorescent material in a mass ratio of 1:4 to 6 to form a temperature measuring layer mixture. Place the temperature measuring layer mixture in a ceramic container in a heating device and heat it to above 500°C until the temperature measuring layer mixture changes from solid to liquid.

[0013] Step (2): Insert the hemispherical structure of the fluorescent optical fiber into the liquid temperature measuring layer mixture obtained in step (1), so that the liquid temperature measuring layer mixture wraps around the spherical surface of the hemispherical structure. Then, remove the hemispherical structure from the liquid temperature measuring layer mixture and suspend it in the heating device until the liquid temperature measuring layer mixture becomes crystalline and adheres to the spherical surface of the hemispherical structure to form a temperature measuring layer.

[0014] Step (3): The temperature measuring layer obtained in step (2) is coated with liquid reinforcing material to form a reinforcing layer, and the reinforcing layer is cured by baking at a temperature of 145-155℃ for a time of not less than 1 hour.

[0015] Further, in step (1), the silicon dioxide is silicon dioxide powder, the fluorescent substance is fluorescent powder, and the mass ratio between silicon dioxide and fluorescent substance is 1:5.

[0016] Furthermore, in step (3), the liquid reinforcing material is a high-temperature resistant epoxy resin adhesive; the baking temperature is 150°C.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] (1) This invention discloses a spherical end face fluorescent fiber structure, which has a high coupling efficiency hemispherical structure at one end of the fluorescent fiber and a temperature measuring structure on the spherical surface of the hemispherical structure. Compared with the flat end face fluorescent fiber structure, this invention has a simple process, a high pass rate, and the spherical end face has no sharp edges or burrs, and the probability of tip discharge is small, making it more suitable for use in harsh environments such as high electric fields.

[0019] (2) In the spherical end face fluorescent fiber structure of the present invention, the temperature measuring structure is divided into a temperature measuring layer and a reinforcement layer. The temperature measuring layer is a mixture of silicon dioxide and fluorescent material, while the high temperature resistant epoxy resin is used as a reinforcement layer to protect the fluorescence from leakage and to reinforce it, thus avoiding the problem of carbonization and yellowing of the temperature measuring layer that would block fluorescence transmission.

[0020] (3) Based on the above-mentioned spherical end face fluorescent fiber structure, the present invention discloses a method for preparing spherical end face fluorescent fiber. Compared with flat end face, spherical end face has higher coupling efficiency and simpler process, which can form a standardized operation. In addition, the present invention improves the existing temperature measurement structure by using a mixture of silica and fluorescent material as the temperature measurement layer for transmitting fluorescent signals, and using high-temperature resistant epoxy resin as a reinforcing layer to prevent fluorescence leakage and reinforce the temperature measurement layer. This solves the problem that high-temperature resistant optical adhesive will cause irreversible carbonization and yellowing at excessively high temperatures, thus blocking fluorescence transmission. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a spherical end-face fluorescent optical fiber structure according to the present invention (temperature measurement structure not shown);

[0022] Figure 2 This is a schematic diagram of the hemispherical structure and temperature measurement structure in a spherical end-face fluorescent fiber structure of the present invention.

[0023] The reference numerals in the attached figures are explained as follows: 1-fluorescent optical fiber; 2-hemispherical structure; 3-temperature measuring structure; 31-temperature measuring layer; 32-reinforcing layer. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and exemplary embodiments.

[0025] Reference Figure 1 and Figure 2A spherical end-face fluorescent fiber structure includes a fluorescent fiber 1, one end of which is an LED light source, and the other end is a hemispherical structure 2. A temperature measuring structure 3 is disposed on the spherical surface of the hemispherical structure 2. The hemispherical structure 2 is a hemispherical fiber fused together. The temperature measuring structure 3 includes a temperature measuring layer 31 connected to the spherical surface of the hemispherical structure 2 and a reinforcing layer 32 disposed outside the temperature measuring layer. The temperature measuring layer 31 and the reinforcing layer 32 are fixed to the hemispherical structure by thermosetting. The temperature measuring layer 31 is a mixture of silica and fluorescent material, wherein the silica is silica powder and the fluorescent material is phosphor, and the mass ratio between silica and fluorescent material is 1:5. The reinforcing layer 32 is a high-temperature resistant epoxy resin adhesive.

[0026] Based on the above-mentioned spherical end-face fluorescent fiber structure, this invention discloses a method for fabricating a spherical end-face fluorescent fiber, comprising the following steps:

[0027] Step (1): Mix silica powder and phosphor at a mass ratio of 1:5 to form a temperature measuring layer 31 mixture. Place the temperature measuring layer 31 mixture in a ceramic container in a heating furnace and heat it to above 500°C until the temperature measuring layer 31 mixture changes from solid to liquid.

[0028] Step (2): Insert the hemispherical structure 2 of the fluorescent optical fiber 1 into the liquid temperature measuring layer 31 mixture obtained in step (1), so that the liquid temperature measuring layer 31 mixture wraps around the spherical surface of the hemispherical structure 2. Then, remove the hemispherical structure 2 from the liquid temperature measuring layer 31 mixture. In order to prevent the liquid temperature measuring layer 31 mixture from cracking due to cooling, the removed hemispherical structure 2 is suspended in the heating device for heat preservation until the liquid temperature measuring layer 31 mixture becomes crystalline and adheres to the spherical surface of the hemispherical structure 2, forming the temperature measuring layer 31.

[0029] Step (3): The temperature measuring layer 31 obtained in step (2) is coated with liquid reinforcing material to form a reinforcing layer 32, and the reinforcing layer 32 is cured by baking at a baking temperature of 145-155℃ for 1 hour.

[0030] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. For those skilled in the art, modifications can be made to the specific technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions protected by the present invention.

Claims

1. A spherical end face fluorescent optical fiber structure, comprising a fluorescent optical fiber (1), one end of the fluorescent optical fiber (1) being a hemispherical structure (2), characterized in that: a temperature measurement structure (3) is further arranged on the spherical surface of the hemispherical structure (2), the temperature measurement structure (3) comprising a temperature measurement layer (31) connected with the spherical surface of the hemispherical structure (2) and a reinforcing layer (32) arranged outside the temperature measurement layer; the temperature measurement layer (31) is a mixed crystal-like substance of silica and fluorescent substance, and the reinforcing layer (32) is high-temperature resistant epoxy resin glue. The silica is silica powder, and the fluorescent substance is fluorescent powder, and the mass ratio between the silica and the fluorescent substance is 1:4-6. The temperature measurement structure (3) is adhered to the spherical surface of the hemispherical structure (2) and is fixed by heat curing; the temperature measurement layer (31) is adhered to the spherical surface of the hemispherical structure (2) by temperature control curing, and the reinforcing layer (32) is wrapped on the temperature measurement layer (31) by baking curing. The hemispherical structure (2) is a hemispherical optical fiber fired by fusion. The hemispherical structure (2) is a resin hemispherical lens.

2. A spherical end face fluorescent optical fiber structure according to claim 1, characterized in that: The spherical end face fluorescent optical fiber structure according to claim 1 comprises the following steps:

3. A method for fabricating a spherical end-face fluorescent optical fiber, characterized in that, Step (1), mixing silica and fluorescent substance according to a mass ratio of 1:4-6 to form a temperature measurement layer (31) mixture, and placing the temperature measurement layer (31) mixture in a ceramic container arranged in a heating device and heating to a temperature above 500℃ until the temperature measurement layer (31) mixture changes from solid to liquid; The silica is silica powder, and the fluorescent substance is fluorescent powder. Step (2), inserting the hemispherical structure (2) of the fluorescent optical fiber (1) into the liquid temperature measurement layer (31) mixture obtained in step (1) to wrap the liquid temperature measurement layer (31) mixture on the spherical surface of the hemispherical structure (2), and then taking the hemispherical structure (2) out of the liquid temperature measurement layer (31) mixture and suspending it in the heating device until the liquid temperature measurement layer (31) mixture changes into a crystal-like substance and adheres to the spherical surface of the hemispherical structure (2) to form a temperature measurement layer (31); Step (3), coating a liquid reinforcing material on the temperature measurement layer (31) obtained in step (2) to form a reinforcing layer (32), and curing the reinforcing layer (32) by baking at a baking temperature of 145-155℃ for not less than 1 hour. In step (1), the mass ratio between the silica and the fluorescent substance is 1:

5.

4. A method of making a ball ended face fluorescent optical fiber as defined in claim 3, wherein: In step (3), the liquid reinforcing material is high-temperature resistant epoxy resin glue, and the baking temperature is 150℃.

5. A method of making a ball-ended face fluorescent optical fiber according to claim 3 or 4, wherein: ​

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