Method for making optical fiber light emitter

Abstract

A core material (102) is contained in a cylindrical container (101) (first step). The container (101) is formed from a thermoplastic cladding material. The container (101) can be formed from a heat resistant glass such as a silicon borate glass, for example. The core material (102) is a halide having a lower melting point than the cladding material. Next, the container (101) containing the core material (102) is heated using a heater (151) and stretched, thereby forming an optical fiber emitter (105) comprising a core (103) formed from a halide crystal, and a cladding (104) formed from the cladding material.

Description

[Technical Field]

[0001] The present invention provides an optical fiber light emitter having a core made of a light emitter. How to make Regarding. [Background technology]

[0002] Optical fiber light emitters with a core made of a scintillator (light emitter) used in radiation measurement to measure radiation such as gamma rays, X-rays, alpha rays, and neutron rays are used as sensor elements for measuring radiation, etc. For example, an optical fiber light emitter made of plastic has been proposed (Patent Document 1).

[0003] Furthermore, eutectic scintillators consisting of multiple crystalline phases have been reported, and it is known that a scintillator with excellent resolution can be obtained when a scintillator with a high refractive index is made into a fiber shape and is surrounded and arranged with a matrix phase with a low refractive index to form an optical waveguide eutectic structure (see Patent Document 2). Therefore, by forming a multicore fiber in which multiple scintillator cores are provided in the same fiber body, it is possible to realize a sensor with positional resolution for radiation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6868643 [Patent Document 2] Patent No. 6468820 Summary of the Invention [Problem to be solved by the invention]

[0005] Halide crystals are known as materials that can produce strong scintillation light. However, because halide crystals are deliquescent, they are difficult to process in the atmosphere, making it difficult to fabricate optical fiber light emitters with a halide crystal core.

[0006] The present invention has been made to solve the above problems, and has as its object to make it easier to fabricate an optical fiber light emitter having a halide crystal core. [Means for solving the problem]

[0007] The method for producing an optical fiber light emitter according to the present invention comprises a first step of placing a core material made of a halide having a lower melting point than the cladding material in a cylindrical container made of a thermoplastic cladding material, and a second step of heating and stretching the container containing the core material to form an optical fiber light emitter consisting of a core made of halide crystals and a cladding made of the cladding material, wherein the halide crystals emit light when irradiated with radiation.

[0008] The method for producing an optical fiber light emitter according to the present invention comprises a first step of preparing a tubular cladding, a second step of melting a halide having a lower melting point than the material constituting the cladding to form a melt, a third step of placing the melt in the cladding, and a fourth step of cooling and solidifying the melt placed in the cladding to form a halide crystal, thereby forming an optical fiber light emitter having a halide crystal as a core, and the halide crystal emits light when irradiated with radiation.

[0009] In one configuration example of the method for producing the optical fiber light-emitting device, the third step sucks the melt into the inside of the clad, thereby containing the melt in the clad.

[0010] In one configuration example of the method for producing the optical fiber light-emitting device, the third step pushes the melt up into the clad, thereby containing the melt in the clad.

[0011] In one example of the method for producing the optical fiber light emitter, the first step is to prepare a clad array in which a plurality of clads are bundled together, and the third step is to fill each clad of the clad array with a melt.

[0012] The method for producing an optical fiber light emitter according to the present invention comprises a first step of placing a core material made of a halide having a melting point lower than that of the material constituting the clad into a tubular clad, a second step of melting the core material placed in the clad, and a third step of cooling and solidifying the melted core material to form a halide crystal, thereby forming an optical fiber light emitter having a halide crystal as its core, and the halide crystal emits light when irradiated with radiation.

[0013] light The fiber illuminator comprises a core made of a luminescent halide crystal and a cladding made of a thermoplastic material.

[0014] light The fiber illuminator has a core made of a scintillator and a clad, and the difference in thermal expansion coefficient between the core and the clad is 60×10 -6 / K and heat transfer Guidance The difference in the refractive index is within 30 W / m / K in at least one state.

[0015] In one example of the optical fiber light emitter, the optical fiber light emitter is a multi-core fiber having a plurality of cores in the same fiber body.

[0016] In one example of the configuration of the optical fiber light emitter, the core diameter, cladding thickness, and outer diameter decrease from one end to the other end.

[0017] In one example of the configuration of the optical fiber light emitter, the cores are rectangular in cross section and are arranged in a rectangular shape in the cross section direction.

[0018] lightThe fiber illuminator has a core and a cladding made of a eutectic having two crystalline phases, at least one of which emits light when exposed to radiation.

[0019] In one configuration example of the optical fiber light emitter, the average crystal grain size of the two crystal phases is set to 30 μm or less.

[0020] In one example of the optical fiber light emitter, the difference in refractive index between the two crystal phases is 0.1 or less at the emission wavelength.

[0021] In one configuration example of the optical fiber light emitter, the average crystal grain size of the two crystal phases is set to 30 μm or less.

[0022] In one example of the optical fiber light emitter, the core is made of an oxide crystal or a halide crystal that emits light when irradiated with radiation.

[0023] release The radiation measurement device comprises the above-mentioned fiber optic light emitter.

[0024] The light emitter array is a bundle of multiple optical fiber light emitters as described above.

[0025] release The radiation measurement device comprises the above-described light emitter array.

[0026] The radiation measuring device of the present invention comprises an optical fiber light emitter composed of a core and a cladding made of a scintillator that emits light when irradiated with radiation, a first sensor that detects light that reaches one end of the optical fiber light emitter, a second sensor that detects light that reaches the other end of the optical fiber light emitter, and an arithmetic circuit that determines the incident position of radiation in the optical fiber light emitter based on at least one of the difference in light detection time and the difference in detected light amount between the first sensor and the second sensor.

[0027] In one configuration example of the radiation measuring device, the optical fiber light emitter is formed in a coil shape. [Effects of the Invention]

[0028] As described above, according to the present invention, a halide having a lower melting point than the material is placed in a cylindrical container made of a thermoplastic material, and then the container is heated and stretched, thereby making it easier to produce an optical fiber light emitter having a halide crystal as its core. [Brief explanation of the drawings]

[0029] [Figure 1A] FIG. 1A is a configuration diagram showing an intermediate step in a method for producing an optical fiber light emitter according to a first embodiment of the present invention. [Figure 1B] FIG. 1B is a configuration diagram showing an intermediate step in the method for producing an optical fiber light emitter according to the first embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view showing the configuration of the optical fiber light emitter according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a perspective view showing the configuration of another optical fiber light emitter according to the first embodiment of the present invention. [Figure 4A] FIG. 4A is a configuration diagram showing an intermediate step in a method for producing another optical fiber light emitter according to the first embodiment of the present invention. [Figure 4B] FIG. 4B is a configuration diagram showing an intermediate step in the method for producing another optical fiber light emitter according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a configuration diagram showing an intermediate step in a method for producing another optical fiber light emitter according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart illustrating a method for producing an optical fiber light emitter according to the second embodiment of the present invention. [Figure 7A] FIG. 7A is a perspective view showing the configuration of a cladding array 200 in the middle of a process, illustrating a method for producing another optical fiber light emitter according to the second embodiment of the present invention. [Figure 7B] FIG. 7B is a perspective view showing the configuration of the cladding array 200 in the middle of a process, illustrating the method for producing another optical fiber light emitter according to the second embodiment of the present invention. [Figure 8] FIG. 8 is a flowchart illustrating a method for producing an optical fiber light emitter according to the third embodiment of the present invention. [Figure 9] FIG. 9 is a perspective view showing the configuration of an optical fiber light emitter 300 according to the fourth embodiment of the present invention. [Figure 10] FIG. 10 is a perspective view showing the configuration of an optical fiber light emitter 300a according to the fourth embodiment of the present invention. [Figure 11] FIG. 11 is a perspective view showing the configuration of an optical fiber light emitter 300b according to the fourth embodiment of the present invention. [Figure 12] FIG. 12 is a cross-sectional view showing the configuration of an optical fiber light emitter 300c according to the fourth embodiment of the present invention. [Figure 13] Figure 13 is a photograph showing the waveguiding state of scintillator light generated in an optical fiber light emitter that was actually fabricated. [Figure 14] FIG. 14 is a photograph showing the results of observing the core at the end face of an actually fabricated optical fiber light emitter using an electron microscope. [Figure 15] FIG. 15 is a diagram showing the configuration of a radiation measuring device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] A method for producing an optical fiber light emitter according to the first embodiment of the present invention will be described below.

[0031] [Embodiment 1] A method for producing an optical fiber light emitter according to the first embodiment of the present invention will be described below with reference to FIGS. 1A and 1B.

[0032] First, as shown in FIG. 1A, a core material 102 is placed in a cylindrical container 101 (step 1). The container 101 is made of a thermoplastic cladding material. For example, the container 101 can be made of heat-resistant glass such as borosilicate glass. The core material 102 is a halide with a lower melting point than the cladding material. For example, the core material 102 can be a material for obtaining halide crystals such as Tl:CsI, Eu:SrI2, CeBr3, Ce:LaBr3, Ce:LaCl3, or CaI2. Because these materials are deliquescent, it is important that the core material 102 be placed in (filled into) the container 101 in a humidity-free (humidity-controlled) environment. For example, the core material 102 can be placed in the container 101 in an argon atmosphere with zero humidity.

[0033] Next, as shown in FIG. 1B, the container 101 containing the core material 102 is heated and stretched by a heater 151. This melts and crystallizes the core material 102 contained in the container 101, forming an optical fiber light emitter 105 consisting of a core 103 made of a halide crystal and a clad 104 made of a clad material (second step). The halide crystal emits light when irradiated with radiation. The halide crystal has a higher refractive index than the clad material. Examples of halide crystals include Tl:CsI, Eu:SrI2, CeBr3, Ce:LaBr3, Ce:LaCl3, and CaI2 crystals.

[0034] It is also important that the above-mentioned process of stretching the container 101 containing the core material 102 by heating be carried out in a humidity-free environment. For example, the above-mentioned stretching can be carried out in an argon atmosphere with zero humidity. Furthermore, in the case of placing the core material 102 in the container 101 described above, if the container 101 is sealed after placing the core material 102 in the container 101 and the placed core material 102 is kept in a state where it is not exposed to the outside air, the above-mentioned stretching can be carried out in the atmosphere.

[0035] The cladding material that constitutes container 101 has a higher melting point than core material 102, and therefore, by heating, container 101 can be softened and stretched, and core material 102 can be melted and crystallized. Furthermore, when core material 102 is melted and crystallized to form core 103, core 103 is covered with cladding 104, so it is not exposed to the surrounding air and problems such as deliquescence do not occur. Furthermore, it goes without saying that core material 102 can be easily accommodated in container 101 in an atmosphere with zero humidity. Thus, according to the first embodiment, optical fiber light emitter 105 having a halide crystal as a core can be produced extremely easily.

[0036] The fabrication method of the first embodiment described above provides an optical fiber light emitter 105, as shown in FIG. 2, which includes a core 103 made of a light-emitting halide crystal and a clad 104 made of a thermoplastic material. The clad 104 is made of glass, for example. The core made of this type of halide crystal has a refractive index n of about 1.8, and a critical angle greater than that of a typical optical fiber can be achieved between the core and the clad 104 made of glass with a refractive index n of 1.46 to 1.5. Furthermore, as shown in FIG. 3, the optical fiber light emitter 105a can also be a multicore fiber having multiple cores 103 in the same fiber body. Furthermore, a plurality of optical fiber light emitters 105 can be bundled together to form an emitter array.

[0037] For example, the optical fiber light emitter 105 (optical fiber light emitter 105a) according to the first embodiment can be used as a sensor element, and can be combined with a light receiving element that can receive scintillation light emitted by the core 103 and guided through the optical fiber light emitter 105, thereby enabling use as a radiation measuring device. Also, the above-mentioned light emitter array can be used as a sensor element to configure the above-mentioned radiation measuring device.

[0038] Furthermore, when a multi-core fiber is used, it can be produced as follows. For example, first, as shown in Fig. 4A, a container 111 having a plurality of cylindrical container portions 112 is prepared, and a core material 102 is placed in each container portion 112 (first step). The container 111 is made of a cladding material having thermoplastic properties. The container 111 can be made of heat-resistant glass such as borosilicate glass.

[0039] Next, as shown in Fig. 4B, the container 111 containing the core materials 102 in each of the housing sections 112 is heated and stretched by the heater 151. This melts and crystallizes the core materials 102 contained in each of the housing sections 112, and an optical fiber light emitter 105a can be formed (second step) that includes multiple cores 103 made of halide crystals and a clad 104a made of a clad material. The optical fiber light emitter 105a becomes a multi-core fiber.

[0040] Furthermore, as shown in FIG. 5, by bundling a plurality of containers 101 and heating and stretching them with a heater 151, it is possible to form a bundle of optical fiber light emitters 105 each consisting of a core 103 and a clad 104 into an array.

[0041] Next, a detailed description will be given using examples. First, a cylindrical heat-resistant glass container with a length of 200 mm, an outer diameter of 25 mm, and an inner diameter of 20 mm was prepared. The heat-resistant glass had a softening point of 820°C. Next, in an argon atmosphere with zero humidity, predetermined amounts of thallium iodide [TlI] powder and cesium iodide [CsI] powder were mixed to form a mixed powder, which was then placed (filled) inside the container. The mixed powder of TlI powder and CsI powder was heated to melt it into a molten liquid, and the molten liquid was appropriately cooled to obtain crystals of thallium-activated cesium iodide [Tl:CsI] (melting point 621°C).

[0042] Next, the top of the container filled with the raw materials (mixed powder) was fixed, and the bottom of the container was heated to 820°C. While heating, the bottom of the container was pulled down. This process was also carried out in an argon atmosphere with zero humidity. The pulling down speed was 1 km per hour. The optical fiber light emitter produced by the pulling down was wound up on a winding device. The optical fiber light emitter was produced with an outer diameter of 100 μm and a length of 10 m. The produced optical fiber light emitter had an inner diameter of 80 μm in the cladding, in which a core made of Tl:CsI crystal was formed. The outer diameter of the formed core was 80 μm.

[0043] The core of the fabricated optical fiber light emitter emitted light at 550 nm when excited by radiation and light, and it was confirmed that light was guided to the end of the optical fiber light emitter. 250,000 of the fabricated optical fiber light emitters were bundled together using adhesive to create a 5 cm square light emitter array, which was then cut to a thickness of 2 mm. The resulting light emitter array exhibited a position resolution of 120 μm for X-rays.

[0044] As described above, according to the first embodiment, a halide having a lower melting point than the material is placed in a cylindrical container made of a thermoplastic material, and then the container is heated and stretched, which makes it easier to fabricate an optical fiber light emitter having a halide crystal as its core. Furthermore, the use of an optical fiber light emitter makes it possible to realize an ultra-high resolution radiation measurement device.

[0045] [Embodiment 2] Next, a method for producing an optical fiber light emitter according to the second embodiment of the present invention will be described with reference to FIG.

[0046] First, in the first step S101, a cylindrical clad is prepared. The clad can be made of heat-resistant glass such as borosilicate glass. Next, in the second step S102, a halide with a lower melting point than the material constituting the clad is melted to form a melt. For example, a melt of the halide is prepared and placed in a predetermined container (such as a crucible). The halide can be Tl:CsI, Eu:SrI2, CeBr3, Ce:LaBr3, Ce:LaCl3, CaI2, BaCl2, etc. Because these types of materials are deliquescent, it is important to prepare the melt in a humidity-free (humidity-controlled) environment.

[0047] Next, in a third step S103, the clad is filled with a melt. For example, the melt can be filled into the clad by sucking it up into the interior of the clad through an opening on one end side of the clad. For example, the melt can be sucked up into the interior of the clad by immersing one end side of the clad in the melt contained in the container described above and evacuating the air inside the clad from the other end side of the clad. Alternatively, the melt can be filled into the clad by pushing it up into the interior of the clad through the opening on one end side of the clad. For example, the melt can be pushed up into the interior of the clad by applying a higher pressure to the melt surface than to the other end side of the clad while one end side of the clad is immersed in the melt contained in the container described above.

[0048] Next, in a fourth step S104, the melt contained in the cladding is cooled and solidified to form a halide crystal, thereby forming an optical fiber light emitter having a halide crystal as its core. The halide crystal emits light when irradiated with radiation. The halide crystal has a higher refractive index than the material constituting the cladding. Examples of halide crystals include Tl:CsI, Eu:SrI2, CeBr3, Ce:LaBr3, Ce:LaCl3, CaI2, and BaCl2. After the halide melt is contained in the cladding, the cladding is sealed to prevent the contained melt from coming into contact with the outside air, and the solidification can be carried out in the atmosphere.

[0049] 7A, a clad array 200 in which a plurality of clads 201 are bundled can be prepared (first step). In this case, a melt is poured into each clad 201 of the clad array 200 (third step). For example, as shown in FIG. 7B, one end of the prepared clad array 200 can be immersed in a container 202 containing a melt of the above-mentioned halide, and the melt is drawn up into each clad 201, thereby allowing the melt to be poured into each clad 201 of the clad array 200. Also, one end of the prepared clad array 200 can be immersed in a container 202 containing a melt of the above-mentioned halide, and the melt is pushed up into each clad 201, thereby allowing the melt to be poured into each clad 201 of the clad array 200.

[0050] After being accommodated in the cladding, the molten halide is covered by the cladding, so it does not come into contact with the surrounding atmosphere and problems such as deliquescence do not occur. Furthermore, it goes without saying that melting a halide in an atmosphere with zero humidity can be easily carried out. Thus, according to the second embodiment, an optical fiber light emitter having a halide crystal as a core can be produced extremely easily.

[0051] [Embodiment 3] Next, a method for producing an optical fiber light emitter according to the third embodiment of the present invention will be described with reference to FIG.

[0052] First, in the first step S121, a core material made of a halide with a melting point lower than that of the cladding material is placed in a cylindrical cladding. The cladding can be made of heat-resistant glass such as borosilicate glass. The core material is a halide with a melting point lower than that of the cladding material. The core material can be, for example, a material for obtaining halide crystals, such as Tl:CsI, Eu:SrI2, CeBr3, Ce:LaBr3, Ce:LaCl3, CaI2, or BaCl2. Because these materials are deliquescent, it is important that the core material be placed in the cladding in a humidity-free (humidity-controlled) environment. For example, the core material can be placed in the cladding in an argon atmosphere with zero humidity.

[0053] Next, in the second step S122, the core material contained in the clad is melted. For example, the core material can be melted by heating the clad containing the core material with a heater to a temperature at which the core material melts. Since the clad has a higher melting point than the core material, the clad does not melt.

[0054] Next, in a third step S123, the molten core material is cooled and solidified to form a halide crystal, thereby forming an optical fiber light emitter having a halide crystal as the core. The halide crystal emits light when irradiated with radiation. The halide crystal has a higher refractive index than the cladding material. Examples of halide crystals include Tl:CsI, Eu:SrI2, CeBr3, Ce:LaBr3, Ce:LaCl3, CaI2, and BaCl2 crystals.

[0055] After the core material is placed in the clad, the clad is sealed to prevent the placed core material from coming into contact with the outside air, and the melting and solidification of the core material described above can be carried out in the atmosphere.

[0056] At the time when the core material is melted and crystallized to form the core, the core is covered with the cladding, so it is not exposed to the surrounding atmosphere and problems such as deliquescence do not occur. Furthermore, it goes without saying that it is easy to accommodate the core material in the cladding in an atmosphere with zero humidity. Thus, according to the third embodiment, an optical fiber light emitter having a halide crystal core can be produced extremely easily.

[0057] The core may have an irregular cylindrical shape such as a cylinder or polygonal pillar, and a plurality of such cores may be arranged in parallel in the cladding to form an array.

[0058] Because the core material has a lower melting point than the cladding material, the core material is melted and crystallized to form the core, and then melted and solidified again within the cladding to recrystallize it. This improves the crystalline quality of the core material and the performance of the light emitter, including the light emission amount, fluorescence lifetime, and energy resolution.

[0059] As described above, according to the second and third embodiments, the halide melt contained in the cladding is cooled and solidified to form a halide crystal, thereby forming an optical fiber light emitter having a halide crystal as its core, thereby making it easier to manufacture an optical fiber light emitter having a halide crystal as its core.

[0060] [Embodiment 4] Next, an optical fiber light emitter 300 according to a fourth embodiment of the present invention will be described with reference to FIG. 9. In the above-described optical fiber light emitter, if the difference in thermal expansion coefficient between the core and the cladding is large, cracks and voids may occur in the internal crystal due to temperature changes, etc., causing degradation of scintillator performance, such as a decrease in transmittance and a decrease in light emission, and ultimately degrading performance as a radiation detector. Furthermore, expansion and cracking of the cladding may occur, damaging the optical fiber light emitter. Cracks may also occur in the cladding if the core has a higher thermal conductivity than the cladding. For example, during the manufacturing process of the optical fiber light emitter, cooling proceeds preferentially from the fibrous core, which is thought to increase thermal strain between the cladding and core, resulting in cracks.

[0061] The optical fiber light emitter 300 according to the fourth embodiment solves the above-mentioned problems and includes a core 301 and a clad 302 made of a scintillator. The difference in thermal expansion coefficient between the core 301 and the clad 302 is 60×10 -6 / K and heat transfer Guidance At least one of the two states is set so that the refractive index difference is within 30 W / m / K. The core 301 can be made of a halide crystal that emits light when irradiated with radiation.

[0062] For example, the above-mentioned optical fiber light emitter can be produced by placing a core material in a cylindrical container made of a cladding material, and then heating and stretching the container containing the core material with a heater. By heating and stretching in this manner, the core material contained in the container melts and crystallizes, resulting in an optical fiber light emitter.

[0063] The results of actual fabrication are described below. A borosilicate glass tube (cylindrical container) with an outer diameter of 20 mm and an inner diameter of 16 mm was filled with the raw materials for each core material listed in Table 1 below, and the silicate glass tube filled with the core material was then filled with argon gas. The silicate glass tube became the cladding material. After this, the temperature inside the furnace was locally raised to the softening point of borosilicate glass (780°C) using a heater, and the borosilicate glass tube filled with the core material was elongated.

[0064] [Table 1]

[0065] As a result, optical fiber luminescent elements were successfully fabricated for TlCsI, Tl:NaI, Ce:LaBr3, CeBr3, and Eu:SrI2, with a core and cladding formed to an inner diameter of 80 μm. Optical fiber luminescent elements with an outer diameter of 100 μm, an inner diameter of 80 μm, and a total length of 3,000 m were fabricated without any cracks or other defects. Furthermore, scintillator light was generated by UV excitation or radiation excitation, and the phenomenon of light being guided within the core was confirmed, demonstrating their functionality as optical fiber luminescent elements. Cr:Al2O3 did not melt under the above conditions when a silicate glass tube was used as a cladding material, and an optical fiber light emitter could not be molded. In addition, as comparative examples, the borosilicate glass tube cracked when Pb and Na were used, and an optical fiber light emitter could not be molded.

[0066] As a comparative example, a cladding material was made of quartz glass with an outer diameter of 20 mm and an inner diameter of 16 mm. This quartz glass was filled with Cr:Al2O3 raw material, and the quartz glass tube was filled with argon gas. The material was then locally heated to the softening point of the quartz glass (1700°C) using a heater and stretched. As a result, the quartz glass and the Cr:Al2O3 raw material reacted during the heating process, producing a compound formed by the reaction between the quartz glass tube and Cr:Al2O3, which damaged the quartz glass tube and prevented the formation of an optical fiber light emitter. Materials such as oxides that react below the softening point of the glass material were not suitable as core materials.

[0067] In addition, a quartz glass cladding material with an outer diameter of 20 mm and an inner diameter of 16 mm was used, and the quartz glass was filled with the raw material for the Tb:GdAlO3 / Al2O3 eutectic. The quartz glass tube was then filled with argon gas, and the material was locally heated using a heater to approximately 1700°C, the melting point of the Tb:GdAlO3 / Al2O3 eutectic and the softening point of the quartz glass, before being stretched. As a result, the quartz glass and the raw material for the Tb:GdAlO3 / Al2O3 reacted during the heating process, damaging the quartz glass tube and preventing the formation of an optical fiber light emitter. Oxide eutectics, which react below the softening point of the glass material, were also not suitable as core materials.

[0068] It is desirable that the core be a crystal that is transparent to the scintillator light. For this reason, the scintillator that makes up the core should have 100 grains or less per square mm, and more preferably 2 grains or less per square mm. This is because when the scintillator light generated by UV excitation or radiation excitation is guided through the core, the light is attenuated by scattering and absorption at the grain boundaries, degrading its performance as a radiation detector.

[0069] The results of actual fabrication are described below. A borosilicate glass tube (cylindrical container) with an outer diameter of 20 mm and an inner diameter of 16 mm was filled with LaBr3:Ce (melting point: 783°C, refractive index: 1.9) as the core material, and argon gas was filled inside the glass tube. The temperature was locally raised above the softening point of the borosilicate glass (830°C) using a heater, and the tube was stretched. As a result, an optical fiber light emitter was fabricated with a core made of Cs2LiYCl6:Ce scintillator and an inner diameter of 160 μm. The optical fiber light emitter was fabricated without cracks or other defects, with an outer diameter of 200 μm, an inner diameter of 160 μm, and a total length of 1000 m. Measurement of the emission spectrum using X-ray excitation confirmed emission with a peak at 370 nm. This optical fiber light emitter generated scintillator light upon UV excitation or radiation excitation, and the phenomenon of light waveguiding within the core was confirmed, demonstrating its functionality as an optical fiber light emitter.

[0070] The resulting fiber optic emitter was cut to a length of 10 mm, the end surfaces mirror-polished, and optically bonded to a photomultiplier tube. In this state, the fiber optic emitter was irradiated with 662 keV gamma rays from a 137Cs source. The signal from the photomultiplier tube was input to a preamplifier, a pulse-shaping amplifier, and then to a multichannel analyzer to measure the light emission using pulse counting. As a result, a pulse-height spectrum was successfully obtained, confirming a photoelectric absorption peak corresponding to the 662 keV gamma rays and an emission intensity of 40,000 photons / MeV. EBSD observation of the core at the end of the fiber optic emitter, which has an inner diameter of 160 μm, revealed that LaBr3:Ce crystals were densely packed within the cladding, with six grains identified within.

[0071] The resulting 1000-m-long optical fiber illuminator was then cut into 10-mm lengths. It was then heated above the melting point of LaBr3:Ce to melt the core, followed by unidirectional solidification along the fiber length at a rate of 0.1 mm / min, resulting in recrystallization. EBSD observation of the core at the end of the 160-μm-diameter optical fiber illuminator revealed that the LaBr3:Ce crystals were densely packed within the cladding, with a single grain identified within, confirming its single crystal nature. The end was then mirror-polished and optically bonded to a photomultiplier tube. It was then irradiated with 662-keV gamma rays from a 137Cs source, and the light emission was measured using pulse counting. A pulse-height spectrum was successfully obtained, confirming a photoelectric absorption peak corresponding to the 662-keV gamma rays, and a light emission of 6000 photons / MeV was obtained.

[0072] As a comparative example, a 10mm hollow borosilicate glass tube with an outer diameter of 200μm, an inner diameter of 160μm, and a crushed powder of LaBr3:Ce scintillator was filled as the core material. The end face was then optically bonded to a photomultiplier tube, and 662keV gamma rays from a 137Cs source were irradiated. The amount of light emitted was measured using pulse counting. No clear photoelectric absorption peak was observed, and the amount of light emitted could not be detected. When the core at the end face of the optical fiber light emitter, which had an inner diameter of 160μm, was observed using an SEM, 80 crystal grains and voids around the crystal grains were confirmed inside.

[0073] The above results show that by melting and recrystallizing only the internal core of the fabricated optical fiber light emitter, the number of crystal grains can be reduced, ideally resulting in a single crystal. Optical fiber light emitters with single-crystal cores emitted greater light. This demonstrates that recrystallizing the core of an optical fiber light emitter can improve its scintillator properties. On the other hand, when the core is powder rather than crystalline, the presence of crystal grains and voids attenuates the light due to scattering and absorption when the scintillator light generated by UV or radiation excitation is guided through the core, which is thought to be why no clear photoelectric absorption peak was observed and the amount of light emitted could not be detected.

[0074] The ratio of the initial outer diameter to the inner diameter of the glass tube used for fabrication determines the ratio of the core to the clad thickness of the optical fiber light emitter. Therefore, by changing the specifications of the glass tube and stretching it, the core to clad thickness ratio can be optimized to suit the purpose of the radiation detector, the radiation energy to be detected, and the characteristics of the particles. Furthermore, the core diameter can be optimized from 0.1 μm to 5 mm. The ratio of the diameter of the core 301 to the thickness of the clad 302 can be in the range of 10,000:1 to 1:10,000. Since the clad is an area that is insensitive to radiation, the wider the core, the better the sensitivity of the radiation detector.

[0075] 10, the optical fiber light emitter 300a can also be a multi-core fiber having multiple cores 301 in the same fiber body (clad 302a). Also, a light emitter array can be formed by bundling multiple optical fiber light emitters 105.

[0076] Furthermore, when a multi-core fiber is used, an optical fiber light emitter 300b can be configured such that the diameter of the core 301, the thickness of the cladding 302, and the outer diameter decrease from one end to the other end, as shown in Fig. 11. For example, a two-dimensional image sensor is placed at one end of the optical fiber light emitter 300b, with each pixel of the two-dimensional image sensor corresponding to each core 301. In this state, the other end is placed near the object to be observed.

[0077] The pitch of each pixel in a two-dimensional image sensor is generally about 10 μm. If the optical fiber light emitter 300b is fabricated with the pitch of each core 301 at one end side of the optical fiber light emitter 300b being 10 μm, each pixel of the two-dimensional image sensor can be made to correspond to each core 301 at the one end side.

[0078] On the other hand, at the other end of the fiber optic light emitter 300b, the pitch of the cores 301 can be, for example, 1 μm. When the other end of the fiber optic light emitter 300b fabricated in this manner is placed near an object to be observed, radiation generated at the object to be observed enters the other end of the fiber optic light emitter 300b. At the other end of the fiber optic light emitter 300b where the radiation is incident, light is emitted for each of the multiple cores 301 according to the intensity of the incident radiation. The emitted light is guided through the fiber optic light emitter 300b and reaches one end of the fiber optic light emitter 300b. The emitted light that has reached one end of the fiber optic light emitter 300b is received by each pixel of the two-dimensional image sensor.

[0079] For example, the number of pixels of the two-dimensional image sensor is assumed to be 1000 x 1000, and the optical fiber light emitter 300b is a multi-core fiber consisting of 1000 x 1000 cores 301. At the other end of the optical fiber light emitter 300b, a radiographic image showing the intensity distribution of the generated radiation is received in 1000 x 1000 pixels with a 1 μm pitch, and when this radiographic image reaches one end of the optical fiber light emitter 300b, it becomes 1000 x 1000 pixels with a 10 μm pitch and is captured by the two-dimensional image sensor.

[0080] In this way, by using the optical fiber light emitter 300b, a radiation image with a resolution of 1 μm pitch received at the other end can be enlarged to the light receiving area of ​​a two-dimensional image sensor with a pixel pitch of 10 μm.The reverse is also possible.

[0081] 12, an optical fiber light emitter 300c can be formed by a plurality of cores 301a having a rectangular cross section and a cladding 302b. The optical fiber light emitter 300c is a multi-core fiber. The plurality of cores 301a are arranged in a rectangular shape in the cross section direction.

[0082] Generally, in a two-dimensional image sensor, each pixel is rectangular in plan view, and the pixels are arranged in a rectangular shape. By using the fiber optic light emitter 300c for a two-dimensional image sensor having such a light receiving surface, it is possible to match the geometric correspondence between each pixel of the two-dimensional image sensor and the end face of each core 301a of the fiber optic light emitter 300c. As a result, the light (optical image) emitted from one end side of the fiber optic light emitter 300c can be received by the two-dimensional image sensor with high light detection efficiency. Furthermore, since the cladding 302b is an area insensitive to radiation, the sensitivity is improved by making the core 301a as wide as possible.

[0083] [Embodiment 5] Next, an optical fiber light emitter according to a fifth embodiment of the present invention will be described. This optical fiber light emitter has a core made of a scintillator and a cladding, and the core is made of a eutectic having two crystalline phases. At least one crystalline phase of the eutectic constituting the core emits light when exposed to radiation.

[0084] By using a eutectic, the melting point is lower than that of a single crystal such as a monocrystal, cracks and voids are less likely to occur, and bending as a fiber is tolerated, improving mass production and ease of handling in practical use. The difference in thermal expansion coefficient between the core and cladding is 60 x 10 -6 / K and heat transfer Guidance It is also possible to set at least one of the states in which the refractive index difference is within 30 W / m / K.

[0085] Furthermore, the refractive index difference between the two crystalline phases of the eutectic constituting the core can be 0.1 or less at the emission wavelength. By making the refractive index difference between the crystalline phases of the eutectic constituting the core small, preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.02 or less, light emitted by radiation excitation is guided through the core without attenuation. As a result, according to the fifth embodiment, transparency at the emission wavelength is high, and even if the optical fiber light emitter is long, attenuation of the guided light is small.

[0086] Furthermore, the average particle size of the two crystalline phases of the eutectic that constitute the core can be set to a size sufficiently close to the emission wavelength. Furthermore, the average particle size of each of the two crystalline phases of the eutectic that constitute the core can be preferably set to 30 μm or less. The average particle size of each of the two crystalline phases of the eutectic that constitute the core can be set to more preferably 5 μm or less, and even more preferably 0.5 μm or less. By doing so, light emitted by radiation excitation is guided through the core without attenuation. Light scattering at the grain boundaries can be reduced, and the attenuation of light passing through the core can be reduced, thereby improving linearity. As a result, according to the fifth embodiment, transparency at the emission wavelength is high, and even if the optical fiber light emitter is long, attenuation of the guided light can be reduced.

[0087] In the eutectic, the grain size of the crystalline phase λ and the solidification rate v are related by the following equation: 2 ∝σ α / β D (A-B) L It is known that there is a relation between σ and v. α / β :Interfacial energy, D (A-B) L : The interfacial energy and interdiffusion coefficient are specific values ​​depending on the chemical composition of the eutectic, and the square of the grain size of the crystalline phase is inversely proportional to the solidification rate. In other words, the faster the solidification rate, the smaller the grain size of the crystalline phase.

[0088] The crystalline phase preferably contains at least one rare earth element selected from Pr, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Dy, Er, Tm, Yb, Tl, Pb, Bi, Ag, Ti, and Cr as a luminescence center, at least 0.001 mol % relative to the total substance amount of the crystalline phase of the core. x B y C z X x+2y+3zIt contains a halide represented by (0≦x<1, 0<y≦1, 0<z≦1), A is an element containing at least one of Li, Na, K, Rb, Cs, Cd, B is Zn, Be, Mg, Ca, Sr, Ba, C is an element containing at least one of Y, Ce, La, Gd, Lu, Bi, Ga, Al, Hf, Zr, and X is an element containing at least one of F, Cl, Br, I, Tl, Se, O, P, S.

[0089] [Table 2]

[0090] [Table 3]

[0091] [Table 4]

[0092] Hereinafter, the actually produced results will be described. A raw material of a eutectic crystal (melting point: 428°C) composed of NaI and CsI with Tl as the luminescence center was filled into a borosilicate glass tube (cylindrical container) with an outer diameter of 10 mm and an inner diameter of 8 mm, and the glass tube was filled with argon gas. The temperature was locally raised to the softening point (780°C) of the borosilicate glass by a heater, and stretching was performed at a speed of 0.1 m / min. As a result, an optical fiber phosphor composed of a NaI / CsI:Tl eutectic crystal scintillator core with an inner diameter of 160 μm was fabricated. An optical fiber phosphor with an outer diameter of 200 μm, an inner diameter of 160 μm, and a total length of 1000 m without defects such as cracks was fabricated. It was confirmed that this optical fiber phosphor functions as an optical fiber phosphor by the phenomenon that each crystal phase of NaI:Tl and CsI:Tl generates scintillation light and light is guided in the core by UV excitation or radiation excitation.

[0093] The resulting fiber optic light emitter was cut to a length of 10 mm, the end surface was mirror-polished, and the end surface was optically bonded to a photomultiplier tube. In this state, the fiber optic light emitter was irradiated with 662 keV gamma rays from a 137Cs source, and the emitted light amount was measured using pulse counting. As a result, a pulse-height spectrum was successfully obtained, and a photoelectric absorption peak corresponding to the 662 keV gamma rays was confirmed, resulting in an emitted light amount of 25,000 photons / MeV. Observation of the core at the end surface of the fiber optic light emitter, which has an inner diameter of 160 μm, using an electron microscope revealed that the average grain size of the NaI:Tl and CsI:Tl crystal phases was 15 μm.

[0094] A borosilicate glass tube (cylindrical container) with an outer diameter of 20 mm and an inner diameter of 16 mm was filled with a eutectic core material consisting of NaI and CsI (melting point 428°C) with Tl as the luminescence center, and argon gas was filled inside the glass tube. The temperature was locally raised to the softening point of the borosilicate glass (780°C) using a heater, and the tube was stretched at a speed of 1 m / min. As a result, an optical fiber luminescent device was fabricated with a core consisting of a NaI / CsI:Tl eutectic scintillator and an inner diameter of 160 μm. An optical fiber luminescent device with an outer diameter of 200 μm, an inner diameter of 160 μm, and a total length of 1000 m was fabricated without cracks or other defects. When excited by UV or radiation, the NaI:Tl and CsI:Tl crystalline phases generated scintillator light, and the light was guided within the core, demonstrating its functionality as an optical fiber luminescent device (Figure 13).

[0095] The resulting fiber optic light emitter was cut to a length of 10 mm, the end surface mirror-polished, and optically bonded to a photomultiplier tube. In this state, the fiber optic light emitter was irradiated with 662 keV gamma rays from a 137Cs radiation source, and the emitted light was measured using pulse counting. A pulse-height spectrum was successfully obtained, confirming a photoelectric absorption peak corresponding to the 662 keV gamma rays, and an emitted light intensity of 33,000 photons / MeV was obtained. Observation of the core at the end surface of the fiber optic light emitter, which had an inner diameter of 160 μm, using an electron microscope revealed that the average grain size of the NaI:Tl and CsI:Tl crystalline phases was 0.3 μm. Figure 14 shows a backscattered electron image of the core. In Figure 14, the black areas represent eutectic crystals of NaI and the white areas represent CsI.

[0096] In the manufacture of eutectic cores, increasing the drawing speed accelerates the solidification rate of the molten core. This tends to reduce the average particle size of each crystalline phase. Although the peak emission wavelength of CsI:Tl was 0.55 nm, an optical fiber illuminator with a NaI / CsI:Tl eutectic core with an average particle size of 0.3 μm emitted more light than an optical fiber illuminator with a NaI / CsI:Tl eutectic core with an average particle size of 15 μm. By making the average particle size sufficiently small relative to the emission wavelength of the scintillator core, light scattering at the grain boundaries was reduced, reducing the attenuation of light passing through the core and improving its directivity, resulting in a higher light output from the optical fiber illuminator.

[0097] The transmittance of the core interior to the scintillator light generated inside the optical fiber illuminator is expressed as "T = e -γt It can be evaluated by the linear transmittance T shown in (1). Here, γ is the light attenuation coefficient and t is the core thickness. γ is the sum of the absorption coefficient and scattering term specific to the sample, but for a core that does not absorb the wavelength of the scintillator light, the latter can be considered. The main light scattering in the core inside the optical fiber illuminator is grain boundary scattering (γ g ) and scattering by vacancies at grain boundaries (γ p ) (γ=γ g +γ p ).

[0098] Each type of scattering is formulated based on optical theory. According to the formulation based on the Rayleigh-Gan's-Debye model, γ g is "γ g =3π 2 d g Δn g 2 / λ 2 ...(2)" Also, γ p is "γ p =6pπ 2 d p Δn p 2 / λ 2 ...expressed as equation (3) where λ is the wavelength of light, p is the porosity, d g is the average grain size of the crystalline phase, d p is the diameter of the void, Δn g is the difference between the maximum refractive index n1 of the birefringent crystalline phase and the average refractive index n2 (Δn g =n1-n2). Also, Δn p is the average refractive index of the crystal, n1, and the refractive index of the material filling the voids, n p The latter is usually assumed to be air (refractive index 1), so "Δn p =n1-1".

[0099] From equation (2), if the difference in refractive index between each crystal phase of the eutectic is sufficiently small, Δn g approaches 0, and γ g approaches 0, eliminating the effect of grain boundaries on scattering. In other words, the linear transmittance T in equation (1) approaches 1, achieving high linear transmittance. In the case of a core made of a eutectic with no voids, γ p approaches 0, and the average grain size d g The smaller γ p This is the eutectic core, which contains multiple crystalline phases but has translucency equal to or greater than that of a single crystal or glass.

[0100] These results show that when the difference in refractive index between different crystalline phases is sufficiently small, light propagates through the eutectic with sufficient linearity, increasing the probability of total reflection at the cladding interface above the critical angle, and achieving optical waveguiding similar to that of a typical optical fiber. On the other hand, when the difference in refractive index between different crystalline phases is greater than 0.1, the linearity of light deteriorates due to light scattering within the crystalline phase with the higher refractive index and at the crystal boundary, increasing the probability of light penetrating into the glass cladding below the critical angle, resulting in a deterioration of optical waveguiding performance.

[0101] Next, a radiation measuring device according to an embodiment of the present invention will be described with reference to Fig. 15. This radiation measuring device includes an optical fiber light emitter 300, a first sensor 311, a second sensor 312, and an arithmetic circuit 313.

[0102] The optical fiber light emitter 300 is the optical fiber light emitter described in each of the above-mentioned embodiments, and is composed of a core and a cladding made of a scintillator that emits light when irradiated with radiation. The first sensor 311 detects light that reaches one end of the optical fiber light emitter 300. The second sensor 312 detects light that reaches the other end of the optical fiber light emitter 300.

[0103] The arithmetic circuit 313 determines the incident position 331 of the radiation in the optical fiber light emitter 300 based on at least one of the difference in the light detection time and the difference in the detected light amount between the first sensor 311 and the second sensor 312. The arithmetic circuit 313 is a computer device equipped with a CPU (Central Processing Unit), a main memory device, an external memory device, etc., and the CPU operates (executes) a program loaded in the main memory device, thereby realizing each of the above-mentioned functions.

[0104] For example, the optical fiber light emitter 300 can be formed into a coil shape. The optical fiber light emitter 300 formed into a coil shape can be used by being wound around a measurement target 351 that generates radiation, such as a nuclear reactor or accelerator.

[0105] For example, consider a case where the radiation incident position is 150 m from one end of the fiber optic light emitter 300 and 30 m from the other end. In this case, the first sensor 311 detects the light approximately 500 ns after the radiation is incident. On the other hand, the second sensor 312 detects the light approximately 100 ns after the radiation is incident. Note that the speed of light is assumed to be 30 cm / ns in this calculation. Furthermore, the amount of photons measured by the first sensor 311 is 9,000 photons, and the amount of photons measured by the second sensor 312 is 10,000 photons.

[0106] The arithmetic circuit 313 determines the position where the radiation is incident on the fiber optic light emitter 300 based on the difference of 400 ns in the light detection times or the difference of 1000 photons in the light intensity. Furthermore, by using the fiber optic light emitter 300 formed in a coil shape, the position where the radiation is incident can be identified three-dimensionally.

[0107] As described above, according to the fourth embodiment, the core and the clad are made of a material having a thermal expansion coefficient difference of 60×10 -6 / K and heat transfer Guidance Since the difference in the refractive index is within 30 W / m / K in at least one state, damage to the optical fiber light emitter due to temperature changes can be suppressed.

[0108] Furthermore, according to the fifth embodiment, the core is made of a eutectic having two crystalline phases, which improves mass productivity and ease of handling in practical use. Compared to a single crystal or other single crystalline body, a eutectic has a lower melting point, making it less susceptible to cracks and voids, and allowing the fiber to bend more easily.

[0109] As described above, according to the present invention, a halide having a lower melting point than the material is placed in a cylindrical container made of a thermoplastic material, and then the container is heated and stretched, thereby making it easier to produce an optical fiber light emitter having a halide crystal as its core.

[0110] Some or all of the above-described embodiments may also be described as, but are not limited to, the following supplementary notes.

[0111] [Appendix 1] A method for producing an optical fiber light emitter, comprising: a first step of placing a core material made of a halide having a lower melting point than that of the cladding material in a cylindrical container made of a thermoplastic cladding material; and a second step of heating and stretching the container containing the core material to form an optical fiber light emitter consisting of a core made of the halide crystal and a cladding made of the cladding material, wherein the halide crystal emits light when irradiated with radiation.

[0112] [Appendix 2] 1. A method for producing an optical fiber light emitter, comprising: a first step of preparing a cylindrical cladding; a second step of melting a halide having a melting point lower than that of a material constituting the cladding to form a melt; a third step of placing the melt in the cladding; and a fourth step of cooling and solidifying the melt placed in the cladding to form a halide crystal, thereby forming an optical fiber light emitter having the halide crystal as a core, wherein the halide crystal emits light when irradiated with radiation.

[0113] [Appendix 3] 3. The method for producing an optical fiber light emitter according to claim 2, wherein the third step comprises sucking the melt into the inside of the clad, thereby containing the melt in the clad.

[0114] [Appendix 4] 3. The method for producing an optical fiber light emitter according to claim 2, wherein the third step is to push the melt into the clad, thereby containing the melt in the clad.

[0115] [Appendix 5] The method for producing an optical fiber light-emitting element according to any one of appendices 2 to 4, wherein the first step comprises preparing a clad array in which a plurality of the clads are bundled together, and the third step comprises placing the melt in each of the clads of the clad array.

[0116] [Appendix 6] A method for producing an optical fiber light emitter, comprising: a first step of accommodating a core material made of a halide having a melting point lower than that of a material constituting the cladding into a cylindrical cladding; a second step of melting the core material accommodated in the cladding; and a third step of cooling and solidifying the molten core material to form a halide crystal, thereby forming an optical fiber light emitter having the halide crystal as its core, wherein the halide crystal emits light when irradiated with radiation.

[0117] [Appendix 7] An optical fiber illuminator comprising a core made of a luminescent halide crystal and a cladding made of a material having thermoplastic properties.

[0118] [Appendix 8] The core and the clad are made of a scintillator, and the difference in thermal expansion coefficient between the core and the clad is 60×10 -6 / K and heat transfer Guidance An optical fiber light emitter characterized in that the difference in refractive index is within 30 W / m / K in at least one state.

[0119] [Appendix 9] 9. The optical fiber light source according to claim 7 or 8, wherein the optical fiber light source is a multi-core fiber having a plurality of the cores in the same fiber body.

[0120] [Appendix 10] 10. The optical fiber light source according to claim 9, wherein the diameter of the core, the thickness of the cladding, and the outer diameter decrease from one end to the other end.

[0121] [Appendix 11] 10. The optical fiber light emitter according to claim 9, wherein the cores are rectangular in cross section and are arranged in a rectangular shape in the cross section direction.

[0122] [Appendix 12] An optical fiber light emitter comprising a core and a cladding made of a eutectic having two crystalline phases, wherein at least one of the crystalline phases emits light when exposed to radiation.

[0123] [Appendix 13] 13. The optical fiber light emitter according to claim 12, wherein the average crystal grain size of the two crystal phases is 30 μm or less.

[0124] [Appendix 14] 13. The optical fiber light emitter according to claim 12, wherein the difference in refractive index between the two crystalline phases is 0.1 or less at the emission wavelength.

[0125] [Appendix 15] 15. The optical fiber light emitter according to claim 14, wherein the average crystal grain size of the two crystal phases is 30 μm or less.

[0126] [Appendix 16] 16. The optical fiber light emitter according to any one of appendices 7 to 15, wherein the core is made of an oxide crystal or a halide crystal that emits light when irradiated with radiation.

[0127] [Appendix 17] A radiation measuring device comprising any one of the optical fiber light emitters of appendix 7 to 16.

[0128] [Appendix 18] An illuminator array comprising a bundle of multiple optical fiber illuminators according to any one of appendices 7 to 16.

[0129] [Appendix 19] 19. A radiation measurement apparatus comprising the emitter array of claim 18.

[0130] [Appendix 20] A radiation measuring device comprising: an optical fiber light emitter composed of a core and a cladding made of a scintillator that emits light when irradiated with radiation; a first sensor that detects light that reaches one end of the optical fiber light emitter; a second sensor that detects light that reaches the other end of the optical fiber light emitter; and an arithmetic circuit that determines the incident position of radiation in the optical fiber light emitter based on at least one of the difference in light detection time and the difference in detected light amount between the first sensor and the second sensor.

[0131] [Appendix 21] 21. The radiation measuring device according to claim 20, wherein the optical fiber light emitter is formed in a coil shape.

[0132] It should be noted that the present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention. [Explanation of symbols]

[0133] 101...container, 102...core material, 103...core, 104...clad, 105...optical fiber illuminator, 151...heater.

Claims

1. A first step of placing a core material made of a halide having a melting point lower than that of the clad material in a cylindrical container made of a thermoplastic clad material, sealing the container, and preventing the placed core material from being exposed to the outside air; a second step of forming an optical fiber light emitter having a core made of the halide crystals and a clad made of the clad material by heating and stretching the container containing the core material; Equipped with The method for producing an optical fiber light-emitting body is characterized in that the halide crystal emits light when irradiated with radiation.

2. A first step of preparing a cylindrical clad; A second step of melting a halide having a melting point lower than that of the material constituting the cladding to form a melt; a third step of containing the melt in the clad and sealing the clad to prevent the contained melt from being exposed to the outside air; a fourth step of cooling and solidifying the melt contained in the clad to form a crystal of the halide, thereby forming an optical fiber light emitter having the halide crystal as a core; Equipped with The method for producing an optical fiber light-emitting body is characterized in that the halide crystal emits light when irradiated with radiation.

3. The method for producing an optical fiber light emitter according to claim 2, The third step is to suck the melt into the inside of the clad, thereby containing the melt in the clad. A method for producing an optical fiber light emitter comprising the steps of:

4. The method for producing an optical fiber light emitter according to claim 2, The third step includes pushing the melt upward into the clad to accommodate the melt in the clad. A method for producing an optical fiber light emitter comprising the steps of:

5. The method for producing an optical fiber light emitter according to any one of claims 2 to 4, The first step includes preparing a clad array in which a plurality of the clads are bundled together; The third step is to contain the melt in the clad of each of the clad arrays. A method for producing an optical fiber light emitter comprising the steps of:

6. a first step of sealing a cylindrical clad with a core material made of a halide having a melting point lower than that of a material constituting the clad, and preventing the core material from being exposed to the outside air; a second step of melting the core material contained in the cladding; A third step of cooling and solidifying the molten core material into a crystal of the halide to form an optical fiber light emitter having the crystal of the halide as a core. Equipped with The method for producing an optical fiber light-emitting body is characterized in that the halide crystal emits light when irradiated with radiation.

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