Peripheral surface light emission linear light guide body and manufacturing method thereof

Abstract

To achieve a peripheral surface light emission linear light guide body with a low manufacturing cost and having high uniformity of light intensity.SOLUTION: A peripheral surface light emission optical fiber 3 according to an embodiment includes: an optical fiber 4 including a core 41 in which an end portion 44 is exposed from a clad 42; and a light scattering resin film 5 including a light-transmissive base material 50 and light scattering particles 51 scattered in the base material 50. The light scattering resin film 5 has a first region 61, a second region 62, and a third region 63 covering an outer peripheral surface of the end portion 44 of the core 41. The minimum film thickness of the second region 62 is equal to or greater than the maximum film thickness of the first region 61, and the minimum film thickness of the third region 63 is equal to or greater than the maximum film thickness of the second region 62. The film thickness of the first region 61 and the second region 62 gradually increases toward a distal end side of the end portion 44 and reaches the maximum film thickness of each region. The film thickness of the third region 63 gradually increases toward the distal end side of the end portion 44, reaches the maximum film thickness of the third region 63, and then gradually decreases to a predetermined film thickness.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a peripheral light-emitting linear light guide and a method for manufacturing the same. [Background technology]

[0002] Catheterization therapy is known in which an optical fiber catheter equipped with an optical fiber is inserted into a hollow organ (e.g., the esophagus or intestine) of the human body, or into a blood vessel or the heart, and the affected area is treated with light emitted from the core of the optical fiber. The present applicant has proposed a peripheral light-emitting linear light guide for use in such catheterization therapy, as described in Patent Document 1.

[0003] The peripheral light-emitting linear light guide described in Patent Document 1 includes an optical fiber whose cladding has been removed to expose the core, and a light-scattering member covering the outer surface of the exposed core. The light-scattering member is composed of a light-transmitting substrate with a higher refractive index than the core, and light-scattering particles dispersed and mixed in the substrate.

[0004] The light scattering member has a plurality of layers with different mixing ratios of light scattering particles to the substrate in order to improve the uniformity of light intensity in the axial direction, and at least a portion of each layer overlaps in the radial direction of the core.

[0005] When forming the light scattering member as described above, a plurality of types of solutions with different mixing ratios of light scattering particles are prepared, and each solution is sequentially applied to the outer periphery of the core and cured. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-158714 Summary of the Invention [Problem to be solved by the invention]

[0007] Optical fiber catheters used in catheter treatment are disposable, and therefore cost reduction is required. However, the peripheral light-emitting linear light guide including the light scattering member formed as described above requires many steps and a long time to form the light scattering member, making it difficult to reduce the cost. [Means for solving the problem]

[0008] A peripheral light-emitting linear light guide according to one embodiment includes an optical fiber including a cladding and a core whose one end is exposed from the cladding, a light-transmitting substrate having a refractive index higher than that of the core, and a light-scattering resin film including light-scattering particles dispersed in the substrate. The light-scattering resin film has a first region, a second region, and a third region covering the outer surface of the end of the core, the first region, the second region, and the third region being arranged in this order from the base end to the tip end of the end. The minimum film thickness of the second region is equal to or greater than the maximum film thickness of the first region, and the minimum film thickness of the third region is equal to or greater than the maximum film thickness of the second region. The film thicknesses of the first and second regions gradually increase toward the tip end of the end, reaching their respective maximum film thicknesses. The film thickness of the third region gradually increases toward the tip end of the end, reaching the maximum film thickness of the third region, and then gradually decreases to a predetermined film thickness.

[0009] A manufacturing method for a peripheral surface-emitting linear light guide according to one embodiment includes an optical fiber including a core having one end exposed from the cladding, and a light-scattering resin film having first, second, and third regions covering the outer surface of the end of the core. The manufacturing method includes an optical fiber processing step of exposing the end of the core from the cladding, a film-forming material preparation step of preparing a solution in which light-scattering particles are dispersed in an optically transparent solvent having a refractive index higher than that of the core, an immersion step of immersing the end of the core in the solution, and a lifting step of lifting the end of the core from the solution. The lifting step includes at least a first step of forming the first region, a second step of forming the second region, and a third step of forming the third region, and the first, second, and third steps are performed in this order. The lifting start speed in the second step is equal to or greater than the maximum lifting speed in the first step, and the lifting start speed in the third step is equal to or greater than the maximum lifting speed in the second step. In the first step, the pulling speed is gradually increased from the pulling start speed to the maximum pulling speed in the first step, in the second step, the pulling speed is gradually increased from the pulling start speed to the maximum pulling speed in the second step, and in the third step, the pulling speed is gradually increased from the pulling start speed to the maximum pulling speed in the third step, and then gradually decreased to a predetermined speed. [Effects of the Invention]

[0010] According to the present invention, it is possible to manufacture a peripheral light-emitting linear light guide having a highly uniform light intensity at low cost. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing a treatment device using a peripheral light-emitting optical fiber as a catheter and a patient to be treated. [Figure 2] 1 is a schematic diagram showing one end (tip) of a peripheral light-emitting optical fiber inserted into a patient's body. [Figure 3]1 is a perspective view showing the appearance of the tip of a peripheral surface emitting optical fiber. FIG. [Figure 4] 3 is a cross-sectional view showing the cross-sectional structure of the tip of a peripheral surface emitting optical fiber. FIG. [Figure 5] FIG. 2 is an explanatory diagram showing the film thickness and length of each region of the light-scattering resin film. [Figure 6] FIG. 1 is an explanatory diagram showing an optical fiber processing step. [Figure 7] FIG. 10 is an explanatory diagram showing a film-forming material preparation step. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] 1 is a graph showing the pulling speed in the first step, the second step, and the third step. [Figure 11] 10 is a graph showing the measurement results of the luminous intensity of a peripheral light-emitting optical fiber. DETAILED DESCRIPTION OF THE INVENTION

[0012] An example of an embodiment of the present invention will be described in detail below with reference to the drawings. In all drawings used to explain the embodiment, the same reference numerals are used for the same or substantially the same configurations and elements. Furthermore, as a general rule, once a configuration or element has been explained, it will not be explained again.

[0013] <Overview of treatment device> FIG. 1 is a schematic diagram showing a treatment device 1 that uses a peripheral surface-emitting linear light guiding element according to this embodiment as a catheter, and a patient P to be treated. The treatment device 1 has a main body 2 and a peripheral surface-emitting linear light guiding element 3, and the distal end of the peripheral surface-emitting linear light guiding element 3 is inserted into the body of the patient P. The main body 2 is equipped with a light source 21 that outputs laser light. The laser light output from the light source 21 equipped in the main body 2 is input to the peripheral surface-emitting linear light guiding element 3 from the proximal end of the peripheral surface-emitting linear light guiding element 3. In the following description, the peripheral surface-emitting linear light guiding element 3 may be referred to as a "periphery surface-emitting optical fiber 3."

[0014] <Configuration of peripheral light-emitting linear light guide> Fig. 2 is a schematic diagram showing one end (tip) of the circumferential light-emitting optical fiber 3 inserted into the body of a patient P. In Fig. 2, a part of a blood vessel P1 of the patient P is cut away to show the tip of the circumferential light-emitting optical fiber 3 inserted into the blood vessel P1.

[0015] The laser light Lr scattered and emitted from the tip of the peripheral light emitting optical fiber 3 is irradiated onto the treatment area P2, activating the drug contained in advance in the treatment area P2, thereby performing intravascular laser treatment.

[0016] Fig. 3 is a perspective view showing the appearance of the tip of the circumferential surface emitting optical fiber 3. Fig. 4 is a cross-sectional view showing the cross-sectional structure of the tip of the circumferential surface emitting optical fiber 3. The circumferential surface emitting optical fiber 3 includes an optical fiber 4 that guides the input laser light to the treatment area P2, and a light-scattering resin film 5 provided on one end (tip) of the optical fiber 4.

[0017] 3 and 4, for the sake of convenience of explanation, the film thickness of the light-scattering resin film 5 is exaggerated.

[0018] Optical fiber The optical fiber 4 has a core 41, a cladding 42, and a sheath 43. At the tip of the optical fiber 4, the cladding 42 is exposed from the sheath 43, and the core 41 is also exposed from the cladding 42.

[0019] That is, the optical fiber 4 includes a core 41, one end of which is exposed from the cladding 42. In the following description, the one end of the core 41 exposed from the cladding 42 may be referred to as the "exposed end 44" to distinguish it from other parts of the core 41. In addition, the outer peripheral surface of the exposed end 44 may be referred to as the "outer peripheral surface 44a," and the end face of the exposed end 44 may be referred to as the "tip face 44b."

[0020] The core 41 of the optical fiber 4 is made of silica glass, and the cladding 42 is made of polymer. In other words, the optical fiber 4 is a silica glass optical fiber. The sheath 43 of the optical fiber 4 is made of fluorine-based resin. More specifically, the sheath 43 is made of ETFE (ethylene tetrafluoroethylene polymer).

[0021] The diameter D1 of the core 41 is 200 mm±5 μm, the diameter D2 of the cladding 42 is 225 mm±5 μm, and the diameter D3 of the sheath 43 is 500 mm±30 μm. The refractive index of the core 41 is higher than the refractive index of the cladding 42. Therefore, light incident on the core 41 is totally reflected at the interface between the core 41 and the cladding 42 and propagates within the core 41.

[0022] ≪Light scattering resin film≫ The light-scattering resin film 5 covers a predetermined area of ​​the exposed end portion 44. At the base of the exposed end portion 44, there is an uncovered portion 44c that is not covered by either the cladding 42 or the light-scattering resin film 5.

[0023] The light-scattering resin film 5 scatters and radiates light emitted from the surfaces (outer peripheral surface 44a and tip surface 44b) of the exposed end portion 44. The light-scattering resin film 5 includes a light-transmitting base material 50 having a refractive index higher than that of the core 41, and a large number of light-scattering particles 51 that scatter light incident on the base material 50.

[0024] The substrate 50 is made of a thermosetting resin, and in this embodiment, a silicone resin is used. The refractive index of the silicone resin is, for example, 1.52. On the other hand, the refractive index of the core 41 is, for example, 1.46.

[0025] The light scattering particles 51 are metal particles that reflect light incident on the substrate 50, and in this embodiment, rutile titanium oxide is used. However, the light scattering particles 51 are not limited to titanium oxide. For example, fine metal powder of aluminum oxide (alumina), silver, copper, iron, or an alloy thereof may also be used as the light scattering particles 51.

[0026] The light scattering particles 51 are dispersed and mixed at a constant rate throughout the substrate 50. Dispersed and mixed at a constant rate here means that the light scattering particles 51 are not concentrated in a part of the substrate 50, but are mixed so as to be evenly scattered throughout the substrate 50. Note that the light scattering particles 51 are so fine that they cannot be seen with the naked eye, but the size of the light scattering particles 51 is exaggerated in the drawings accompanying this specification.

[0027] <Each area of ​​the light-scattering resin film> The light-scattering resin film 5 has a first region 61, a second region 62, a third region 63, a fourth region 64, and a fifth region 65. The first region 61, the second region 62, the third region 63, the fourth region 64, and the fifth region 65 are arranged in this order from the base end side (root side) to the tip end side of the exposed end portion 44. The first region 61, the second region 62, the third region 63, and the fourth region 64 cover the entire periphery of the outer surface 44a of the exposed end portion 44, and the fifth region 65 covers the entire tip end surface 44b of the exposed end portion 44.

[0028] The film thickness of the light-scattering resin film 5 gradually increases in the order of the first region 61, the second region 62, and the third region 63. On the other hand, the film thickness of the fourth region 64 of the light-scattering resin film 5 is substantially constant and is thinner than the minimum film thickness of any of the first region 61, the second region 62, and the third region 63. The fifth region 65 of the light-scattering resin film 5 has a roughly hemispherical shape.

[0029] The film thickness of the light-scattering resin film 5 is the thickness of the light-scattering resin film 5 in a direction perpendicular to the central axis CA of the core 41.

[0030] From another perspective, the first region 61, second region 62, and third region 63 of the light-scattering resin film 5 are "gradually increasing portions" whose thickness gradually increases toward the tip side of the exposed end portion 44. The fourth region 64 of the light-scattering resin film 5 is an "annular thin-walled portion" or a "cylindrical thin-walled portion" provided on the tip side of the gradually increasing portion. The fifth region 65 of the light-scattering resin film 5 is a "tip covering portion" provided on the tip side of the annular thin-walled portion or the cylindrical thin-walled portion.

[0031] <Length of each area> 5 is an explanatory diagram showing the film thickness and length of each region of the light-scattering resin film 5. In the following description, "length" means the length along the central axis CA of the core 41 (axial length) unless otherwise specified.

[0032] The length CL of the exposed end 44 of the core 41 is 58.0 mm, and the length L from the beginning of the first region 61 to the end of the third region 63 of the light-scattering resin film 5 is 54.0 mm. More specifically, the length L1 of the first region 61 of the light-scattering resin film 5 is 20.0 mm, the length L2 of the second region 62 is 20.0 mm, and the length L3 of the third region 63 is 14.0 mm. Furthermore, the length L4 of the fourth region 64 of the light-scattering resin film 5 is 2.0 mm, and the length L0 of the uncoated portion 44c of the core 41 is 2.0 mm.

[0033] As described above, the length L2 of the second region 62 is equal to or greater than the length L1 of the first region 61 (L2≧L1). More specifically, the length L2 of the second region 62 is equal to the length L1 of the first region 61 (L2=L1).

[0034] Furthermore, the length L3 of the third region 63 is shorter than the length L1 of the first region 61 and shorter than the length L2 of the second region 62 (L1, L2>L3).

[0035] As described above, in the light-scattering resin film 5 of the present embodiment, the relationship L1≧L2>L3 is satisfied, and the relationship L1, L2, L3>L4 is also satisfied.

[0036] <Film thickness of the first region> The film thickness of the first region 61 gradually increases toward the tip side of the exposed end 44 and reaches a maximum film thickness T1max. As a result, the surface of the first region 61 is inclined with respect to the central axis CA of the core 41. In other words, the surface of the first region 61 is a tapered surface.

[0037] <Film thickness of the second region> The film thickness of the second region 62 gradually increases from a minimum film thickness T2min to a maximum film thickness T2max toward the tip side of the exposed end portion 44. As a result, the surface of the second region 62, like the surface of the first region 61, is inclined with respect to the central axis CA of the core 41. In other words, the surface of the second region 62 is a tapered surface like the surface of the first region 61.

[0038] The minimum thickness T2min of the second region 62 is equal to or greater than the maximum thickness T1max of the first region 61 (T2min≧T1max). More specifically, the minimum thickness T2min of the second region 62 is equal to the maximum thickness T1max of the first region 61 (T2min=T1max).

[0039] Furthermore, the maximum film thickness T2max of the second region 62 is greater than the maximum film thickness T1max of the first region 61 (T2max>T1max).

[0040] <Film thickness of the third region> The thickness of the third region 63 gradually increases from a minimum thickness T3min to a maximum thickness T3max toward the tip of the exposed end 44. After reaching the maximum thickness T3max, the thickness of the third region 63 gradually decreases to a predetermined thickness T3mid toward the tip of the exposed end 44. As a result, the surface of the third region 63 is inclined with respect to the central axis CA of the core 41. Moreover, the surface of the third region 63 is generally tapered overall.

[0041] The minimum thickness T3min of the third region 63 is equal to or greater than the maximum thickness T2max of the second region 62 (T3min≧T2max). More specifically, the minimum thickness T3min of the third region 63 is equal to the maximum thickness T2max of the second region 62 (T3min=T2max).

[0042] The maximum film thickness T3max of the third region 63 is greater than the maximum film thickness T2max of the second region 62 (T3max>T2max). Furthermore, the maximum film thickness T3max is the maximum film thickness of the light-scattering resin film 5. That is, the thickest part of the light-scattering resin film 5 is present in the third region 63.

[0043] Furthermore, the predetermined film thickness T3mid is thinner than the maximum film thickness T3max of the third region 63 and thicker than the minimum film thickness T3min (T3min < T3mid < T3max).

[0044] ≪Film Thickness of the Fourth Region≫ The film thickness of the fourth region 64 is thinner than the film thickness of the first region 61 throughout the entire fourth region 64. Furthermore, as described above, the film thickness of the fourth region 64 is substantially constant throughout the entire fourth region 64. As a result, the surface of the fourth region 64 is parallel to the central axis CA of the core 41.

[0045] As described above, in the light-scattering resin film 5 in the present embodiment, the relationship of T1max ≦ T2min < T2max ≦ T3min < T3mid < T3max is satisfied.

[0046] Note that as a result of the film thickness of the light-scattering resin film 5 changing as described above along the axial direction of the exposed end portion 44, an annular stepped surface 66 parallel to the tip surface 44b of the exposed end portion 44 is provided between the third region 63 and the fourth region 64.

[0047] <Manufacturing Method> Next, an example of a manufacturing method of the circumferentially emitting optical fiber 3 will be described. The manufacturing method according to the present embodiment includes at least an optical fiber processing step, a film-forming material preparation step, an immersion step, and a pulling-up step.

[0048] Furthermore, the pulling-up step includes at least a first step, a second step, a third step, a fourth step, and a fifth step. The first step, the second step, the third step, the fourth step, and the fifth step are executed in this order.

[0049] ≪Optical Fiber Processing Step≫ FIG. 6 is an explanatory diagram showing the optical fiber processing step. In the optical fiber processing step, as shown in FIG. 6(a), an optical fiber 4 having a core 41, a cladding 42, and a sheath 43 is prepared.

[0050] 6(b), the sheath 43 is removed over an arbitrary length range to expose the cladding 42. In this embodiment, the sheath 43 is removed over 75.0 (mm).

[0051] Thereafter, as shown in FIG. 6(c), the cladding 42 is removed to expose the end of the core 41 from the cladding 42, and the exposed end of the core 41 is cut to a desired length.

[0052] More specifically, the end of the exposed core 41 is cut to any length longer than the intended length of the light-scattering resin film 5. In this embodiment, the unnecessary portion (excess length portion) was cut so that the end of the core 41 was 58.0 (mm).

[0053] The optical fiber processing process described above results in an optical fiber 4 having a core 41 with an exposed end 44 .

[0054] The cladding 42 can be removed using an organic solvent such as acetone. The unnecessary portion of the core 41 can be broken by scratching the core 41 with a sharp jig T and then applying stress to the scratched portion.

[0055] ≪Film-forming material preparation process≫ 7 is an explanatory diagram showing the film-forming material preparation step. In the film-forming material preparation step, light-scattering particles 51 are dispersed and mixed in a light-transmitting solvent 71 having a higher refractive index than the core 41. More specifically, a predetermined amount (e.g., 1 mg / mL) of light-scattering particles 51 is added to and dispersed in the liquid solvent 71 contained in a container 72.

[0056] As a result, a solution 70 (FIG. 8) is obtained in which the light scattering particles 51 are dispersed and mixed at a certain ratio in the solvent 71. In other words, a film forming material is obtained.

[0057] In this embodiment, a silicone resin (refractive index: 1.52) was used as the solvent 71. Rutile-type titanium oxide was used as the light scattering particles 51. In the film forming material preparation step, the viscosity of the solution 70 may be adjusted by adding an organic solvent such as toluene or acetone.

[0058] ≪Soaking process≫ 8 is an explanatory diagram showing the immersion step. In the immersion step, the exposed end 44 of the core 41 is immersed in the solution 70 prepared in the film-forming material preparation step. More specifically, a predetermined length range of the exposed end 44 of the core 41 is immersed vertically in the solution 70.

[0059] In this embodiment, exposed end 44 of core 41 was immersed in solution 70 up to a position 2.0 mm from the end face of cladding 42. In other words, exposed end 44 of core 41 was immersed in solution 70 up to a position 56.0 mm from tip face 44b.

[0060] <Pulling process> 9(a) to 9(d) are explanatory diagrams showing the pulling process. More specifically, FIG. 9(a) is an explanatory diagram showing the first step of the pulling process. Similarly, FIG. 9(b) is an explanatory diagram showing the second step, and FIG. 9(c) is an explanatory diagram showing the third step. FIG. 9(d) is an explanatory diagram showing the state of the optical fiber 4 immediately after the pulling process is completed.

[0061] In the pulling-up process, the exposed end 44 of the core 41 is pulled up vertically from the solution 70 at a predetermined speed to form the light-scattering resin film 5. That is, a light-scattering resin film 5 having a predetermined film thickness and cross-sectional shape is formed by a dip coating film formation method. More specifically, a light-scattering resin film 5 having first to fifth regions 61 to 65 shown in FIGS. 4 and 5 is formed.

[0062] In the pulling-up step using the dip coating film-forming method, the thickness of the solution 70 adhering to the surface of the exposed end 44 (thickness of the coating film) can be controlled by controlling the pulling-up speed of the exposed end 44.

[0063] That is, by controlling the lifting speed of the exposed end portion 44, it is possible to control the film thickness of each region of the light-scattering resin film 5. The thickness of the solution 70 adhering to the surface of the exposed end portion 44 in this step can be calculated by the following formula (1).

[0064]

number

[0065] From the above equation 1, it can be seen that the faster the lifting speed of the exposed end 44, the thicker the thickness of the solution 70 adhering to the surface of the exposed end 44, and the slower the lifting speed of the exposed end 44, the thinner the thickness of the solution 70 adhering to the surface of the exposed end 44.

[0066] Therefore, by increasing or decreasing the pulling speed, the first region 61 to the fourth region 64 having the above-mentioned film thicknesses can be formed.

[0067] FIG. 10 is a graph showing the pulling speeds in the first step (FIG. 9(a)), the second step (FIG. 9(b)), and the third step (FIG. 9(c)).

[0068] ≪1st process≫ The first step shown in Fig. 9(a) is a step of forming the first region 61 shown in Fig. 4 and Fig. 5. As shown in Fig. 5, the film thickness of the first region 61 gradually increases toward the tip side of the exposed end portion 44 and reaches a maximum film thickness T1max.

[0069] Therefore, in the first step, the pulling speed is gradually increased from the pulling start speed V1 in the first step to the maximum pulling speed V2 in the first step.

[0070] More specifically, in the first step, the exposed end 44 of the core 41 is pulled vertically out of the solution 70 at a pulling speed that satisfies a cubic function equation (speed = ax^3 + bx^2 + cx + d (a, b, c, d are rational numbers)).

[0071] ≪Second process≫ The second step of the lifting step shown in Fig. 9(b) is a step of forming the second region 62 shown in Fig. 4 and Fig. 5. As shown in Fig. 5, the film thickness of the second region 62 gradually increases from a minimum film thickness T2min to a maximum film thickness T2max toward the tip side of the exposed end 44.

[0072] The minimum thickness T2min of the second region 62 is the same as the maximum thickness T1max of the first region 61 (T2min=T1max). Furthermore, the maximum thickness T2max of the second region 62 is thicker than the maximum thickness T1max of the first region 61 (T2max>T1max).

[0073] Therefore, in the second step, the pulling speed, which has been gradually increased to the maximum pulling speed V2 in the first step, is continued to be gradually increased to the maximum pulling speed V3 in the second step.

[0074] More specifically, in the second step, the exposed end 44 of the core 41 is pulled vertically out of the solution 70 at a pulling speed that satisfies a cubic function equation (speed = ex^3 + fx^2 + gx + h (e, f, g, h are rational numbers)).

[0075] As described above, the maximum pulling speed V2 in the first step is also the pulling start speed in the second step. In other words, the pulling start speed in the second step is equal to or greater than the maximum pulling speed V2 in the first step.

[0076] ≪3rd process≫ 9(c) is a step of forming the third region 63 shown in Figures 4 and 5. As shown in Figure 5, the film thickness of the third region 63 gradually increases from a minimum film thickness T3min to a maximum film thickness T3max toward the tip side of the exposed end portion 44. After reaching the maximum film thickness T3max, the film thickness of the third region 63 gradually decreases toward the tip side of the exposed end portion 44 to a predetermined film thickness T3mid.

[0077] In addition, the minimum thickness T3min of the third region 63 is the same as the maximum thickness T2max of the second region 62 (T3min=T2max). The maximum thickness T3max of the third region 63 is thicker than the maximum thickness T2max of the second region 62 (T3max>T2max). Furthermore, the predetermined thickness T3mid is thinner than the maximum thickness T3max and thicker than the minimum thickness T3min (T3min <T3mid<T3max)。

[0078] Therefore, in the third step, the pulling speed gradually increased to the maximum pulling speed V3 in the second step is continued to be gradually increased to the maximum pulling speed V4 in the third step. Next, the pulling speed gradually increased to the maximum pulling speed V4 is gradually decreased to a predetermined speed V5.

[0079] More specifically, in the third step, the exposed end 44 of the core 41 is pulled vertically out of the solution 70 at a pulling speed that satisfies a quadratic function (speed = ix^2 + jx + k (i, j, k are rational numbers)).

[0080] As described above, the maximum pulling speed V3 in the second step is also the pulling start speed in the third step. In other words, the pulling start speed in the third step is equal to or greater than the maximum pulling speed V3 in the second step.

[0081] The predetermined speed V5 is slower than the maximum pulling speed V4 in the third step and faster than the pulling start speed V3 in the third step (the maximum pulling speed in the second step) (V3 <V5<V4)。

[0082] <Steps 4 and 5> Although not shown in the drawings, the fourth step is a step of forming a fourth region 64 shown in FIG. 4, and the fifth step is a step of forming a fifth region 65 shown in FIG.

[0083] As described above, the film thickness of the fourth region 64 is smaller than the film thickness of the first region 61 throughout the fourth region 64, and is constant.

[0084] Therefore, in the fourth step, the pulling speed is maintained at a constant speed that is slower than the pulling start speed V1 in the first step.

[0085] As described above, the fifth region 65 covers the entire tip surface 44b of the exposed end 44 and has a generally hemispherical shape. Therefore, in the fifth step, the pulling speed is adjusted so that the fifth region 65 having the shape shown in FIG. 5 is formed.

[0086] 9(d), when the lifting process including the above-mentioned first to fifth steps is completed, the solution 70 is adhered to the periphery of the exposed end portion 44 in a desired thickness. Thereafter, the solution 70 hardens to form the light-scattering resin film 5. At this time, the hardened solvent 71 becomes the base material 50 of the light-scattering resin film 5.

[0087] The viscosity of the silicone resin, which is the solvent 71 of the solution 70, varies greatly depending on the temperature. Therefore, in the pulling-up step, the temperature of the solution 70 may be adjusted by a heating means (e.g., a heater) arranged around the container 72 so that the viscosity of the solution 70 becomes the desired viscosity. In this embodiment, the temperature of the solution 70 is maintained at about 40°C during the pulling-up step.

[0088] In this embodiment, after the pulling-up step, a heat treatment was performed to cross-link the solvent 71 (base material 50).

[0089] <Emission intensity> <Measurement method and results> FIG. 11 is a graph showing the measurement results of the luminous intensity of the peripheral surface emitting optical fiber 3 manufactured by the above manufacturing method.

[0090] In this measurement, laser light output from the light source 21 shown in Figure 1 was incident on the core 41 of the optical fiber 4 from the base end side of the peripheral surface-emitting optical fiber 3, and the intensity of the light emitted radially from the light-scattering resin film 5 was measured.

[0091] The light intensity was measured using an optical power meter equipped with a semiconductor sensor that generates a voltage according to the intensity of the received light. The robot moved the peripheral surface-emitting optical fiber 3 in the axial direction, and the intensity of the light emitted from the light-scattering resin film 5 was measured at 0.4 mm intervals.

[0092] The vertical axis of the graph shown in Figure 11 indicates the light intensity (the output voltage of the semiconductor sensor provided in the optical power meter), and the horizontal axis indicates the measurement position of the light intensity (the distance from the starting end of the first region 61 of the light-scattering resin film 5 to the measurement position).

[0093] In this measurement, approximately the same level of light intensity was measured in the section from a position 2.0 mm away from the end face of the cladding 42 to a position 52.0 mm away (hereinafter referred to as the "uniform light intensity section").

[0094] More specifically, the uniformity of the emission intensity within the uniform emission intensity section was 80%. The uniformity of the emission intensity (%) is an index showing the uniformity of the emission intensity, and is a value obtained by dividing the minimum value of the emission intensity measured within the uniform emission intensity section by the maximum value, and multiplying this value by 100.

[0095] The luminous efficiency of the peripheral surface emitting optical fiber 3 was 88%. The luminous efficiency (%) is an index showing the efficiency of light utilization, and is a value obtained by dividing the intensity of light emitted from the light-scattering resin film 5 by the intensity of light incident on the core 41 of the optical fiber 4 and multiplying this value by 100.

[0096] This measurement confirmed that the peripheral light-emitting optical fiber 3 manufactured by the above manufacturing method had a substantially uniform light intensity distribution as a whole.

[0097] <Actions and Effects of the Present Embodiment> In the peripheral surface-emitting optical fiber 3 of this embodiment, a balance is achieved between the decrease in light intensity within the exposed end 44 of the core 41 and the increase in light-scattering particles 51 contained in the light-scattering resin film 5 covering the exposed end 44 of the core 41, resulting in an approximately uniform light intensity distribution overall.

[0098] The light intensity in the exposed end 44 of the core 41 gradually decreases from the base end side toward the tip end side of the exposed end 44. On the other hand, the film thickness of the light-scattering resin film 5 gradually increases from the base end side toward the tip end side of the exposed end 44.

[0099] Here, the light-scattering particles 51 are mixed so as to be evenly dispersed in the solution 70 which is the material of the light-scattering resin film 5. Therefore, if the film thicknesses of the first region 61, the second region 62, and the third region 63 of the light-scattering resin film 5 are the same, the amount (number) of the light-scattering particles 51 contained in each region will be substantially the same.

[0100] In this case, the intensity of light emitted from the light-scattering resin film 5 also gradually decreases as the intensity of light in the exposed end portion 44 gradually decreases. In other words, a uniform light intensity distribution cannot be obtained.

[0101] However, in the present embodiment of the peripheral surface-emitting optical fiber 3, in which the film thickness of the light-scattering resin film 5 gradually increases from the base end side to the tip end side of the exposed end 44, the second region 62 contains more light-scattering particles 51 than the first region 61, and the third region 63 contains more light-scattering particles 51 than the second region 62.

[0102] As a result, the decrease in light intensity within the exposed end portion 44 is compensated for by the increase in diffused reflection of light by the light scattering particles 51, and an approximately uniform light intensity distribution is obtained overall.

[0103] In this embodiment, the annular thin portion is provided closer to the tip than the third region 63, which is the thickest portion of the light-scattering resin film 5. From another perspective, the fourth region 64, which is located closer to the tip than the third region 63, has a constant film thickness that is thinner than the first region 61.

[0104] The fourth region 64 (annular thin-walled portion) as described above is formed by a fourth step of a pulling-up process in which the pulling-up speed is maintained at a constant speed slower than the pulling-up start speed V1 in the first step.

[0105] According to the fourth step with a slower pulling-up speed compared to the first to third steps, it is possible to prevent the formation of large resin balls around the tip surface 44b of the exposed end portion 44. If large resin balls are formed around the tip surface 44b of the exposed end portion 44, the resin balls will contain many light-scattering particles 51. Then, the light intensity will locally increase in the portion of the resin balls, and there is a risk of a decrease in the uniformity of the light intensity distribution.

[0106] That is, the fourth region 64 (annular thin-walled portion) formed by the fourth step has a function of suppressing a decrease in the uniformity of the light intensity distribution.

[0107] Furthermore, in the present embodiment, after the film thickness of the third region 63 reaches the maximum film thickness, it gradually decreases. In other words, a gradually decreasing portion where the film thickness gradually becomes thinner is provided at the tip of the thickest portion of the light-scattering resin film 5. As a result, a rapid decrease in the light intensity is suppressed, and the uniformity of the light intensity distribution is further improved. In other words, the gradually decreasing portion is an extra length portion that suppresses a rapid decrease in the light intensity due to the influence of the annular thin-walled portion.

[0108] The present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist thereof. For example, the film thickness of each region of the light-scattering resin film 5 can be appropriately changed on the condition that a predetermined relationship is satisfied. However, when the circumferential surface light-emitting linear light guide 3 is used as a catheter, it is desirable that the tip portion of the circumferential surface light-emitting linear light guide 3 inserted into the body of the patient P be as thin as possible. From this viewpoint, it is desirable that the sum of the maximum film thickness T1max of the first region 61, the maximum film thickness T2max of the second region 62, and the maximum film thickness T3max of the third region 63 be smaller than the diameter D1 of the core 41 (T1max + T2max + T3max < D1).

Explanation of reference numerals

[0109] 1...treatment device, 2...main body, 3...circumferential surface-emitting linear light guide (circumferential surface-emitting optical fiber), 4...optical fiber, 5...light-scattering resin film, 21...light source, 41...core, 42...clad, 43...sheath, 44...end (exposed end), 44a...outer surface, 44b...tip surface, 44c...uncoated portion, 50...base material, 51...light-scattering particles, 61...first region, 62...second region, 63...third region, 64...fourth region, 65...fifth region, 66...step surface, 70...solution, 71...solvent, 72...container, CA...central axis, D1, D2, D3...diameter, Lr...laser light, P...patient, P1...blood vessel, P2...treatment area, T...jig

Claims

1. an optical fiber including a cladding and a core having one end exposed from the cladding; a light-transmitting substrate having a refractive index higher than that of the core, and a light-scattering resin film containing light-scattering particles dispersed in the substrate; the light-scattering resin film has a first region, a second region, and a third region that cover an outer peripheral surface of the end portion of the core, the first region, the second region, and the third region are arranged in this order from a base end side to a tip end side of the end portion, the minimum thickness of the second region is equal to or greater than the maximum thickness of the first region; the minimum film thickness of the third region is equal to or greater than the maximum film thickness of the second region; the film thickness of the first region and the second region gradually increases toward the tip end of the end portion and reaches a maximum film thickness of each region; The thickness of the third region gradually increases toward the tip end of the end portion, reaches a maximum thickness of the third region, and then gradually decreases to a predetermined thickness.

2. The peripheral light-emitting linear light-guiding element according to claim 1 , wherein the predetermined thickness is smaller than the maximum thickness of the third region and larger than the minimum thickness of the third region.

3. the light-scattering resin film further includes a fourth region located closer to the tip of the end portion than the third region and covering the outer peripheral surface of the end portion, and a fifth region located closer to the tip of the end portion than the fourth region and covering the end surface of the end portion, the film thickness of the fourth region is thinner than the film thickness of the first region throughout the fourth region; The peripheral surface emitting linear light guide according to claim 1 , further comprising a stepped surface parallel to an end face of the end portion of the core, the stepped surface being provided between the third region and the fourth region.

4. the length of the second region is equal to or greater than the length of the first region; The peripheral surface light-emitting linear light guide according to claim 1 , wherein a length of the third region is shorter than a length of the first region and shorter than a length of the second region.

5. A method for manufacturing a peripheral light-emitting linear light guide, comprising: an optical fiber including a core having one end exposed from a clad; and a light-scattering resin film having a first region, a second region, and a third region covering an outer peripheral surface of the end of the core, an optical fiber processing step of exposing the end of the core from the cladding; a film-forming material preparation step of preparing a solution in which light-scattering particles are dispersed in a light-transmitting solvent having a refractive index higher than that of the core; a dipping step of dipping the end of the core into the solution; and a pulling step of pulling the end of the core out of the solution, the lifting step includes at least a first step of forming the first region, a second step of forming the second region, and a third step of forming the third region; the first step, the second step, and the third step are performed in this order; the lifting start speed in the second step is equal to or greater than the maximum lifting speed in the first step; the lifting start speed in the third step is equal to or greater than the maximum lifting speed in the second step; In the first step, the pulling speed is gradually increased from the pulling start speed to the maximum pulling speed in the first step, In the second step, the pulling speed is gradually increased from the pulling start speed to the maximum pulling speed in the second step, In the third step, the lifting speed is gradually increased from the lifting start speed to the maximum lifting speed, and then gradually decreased to a predetermined speed.

6. The method for manufacturing a peripheral surface-emitting linear light guide according to claim 5 , wherein the predetermined speed is slower than a maximum lifting speed in the third step and faster than a lifting start speed in the third step.

7. the light-scattering resin film further includes a fourth region covering the outer peripheral surface of the end portion and a fifth region covering the end surface of the end portion, the lifting step further includes a fourth step, which is performed after the third step, and which forms the fourth region; and a fifth step, which is performed after the fourth step, and which forms the fifth region; The method for manufacturing a peripheral surface light-emitting linear light guide according to claim 5 , wherein the lifting speed in the fourth step is a constant speed that is slower than the lifting start speed in the first step.

8. the pulling rate in the first step satisfies a cubic function equation (rate = ax^3 + bx^2 + cx + d (a, b, c, d are rational numbers)); the pulling rate in the second step satisfies a cubic function equation (rate = ex^3 + fx^2 + gx + h (e, f, g, h are rational numbers)), 6. The method for manufacturing a peripheral light-emitting linear light guide according to claim 5, wherein the pulling speed in the third step satisfies a quadratic function (speed = ix^2 + jx + k (i, j, k are rational numbers)).

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