JP2023023869A - Peripheral surface light-emission linear light guide body, and method for manufacturing the same - Google Patents

Abstract

To provide a peripheral surface light-emission linear light guide body which suppresses an excessive amount of a light scattering member covering an apical surface of a core, and can improve uniformity of intensity of light in a core radial direction in a range that the light scattering member is formed in a longitudinal direction of the optical fiber, and a method for manufacturing the same.SOLUTION: A peripheral surface light-emission linear light guide body 3 includes: an optical fiber 4 where a core 41 is exposed from a clad 42 on one end in a longitudinal direction; and a light scattering member 5 covering at least a part of an outer peripheral surface 41a of the core 41 in a part exposed from the clad 42 in a predetermined axial length range together with the apical surface 41b of the core 41. Light emitted from the core 41 is scattered/radiated by the light scattering member 5. An apical surface 41b of the core 41 is a convex surface.SELECTED DRAWING: Figure 3

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a peripheral surface emitting linear light guide provided with an optical fiber and a light scattering member, and a manufacturing method thereof.

Conventionally, for example, an optical fiber catheter equipped with an optical fiber is inserted into a hollow organ such as the esophagus and intestines of the human body, or into a blood vessel or heart, and the light emitted from the core of the optical fiber is used for treatment or examination. Treatment and catheterization are performed (see, for example, Patent Document 1).

The light irradiation probe for irradiation treatment described in Patent Document 1 includes a light guide part in which a core is arranged in a cylindrical clad, and light that propagates through the light guide part is scattered around in all directions with respect to the axial direction of the core. and a light scattering irradiation section. The light scattering irradiation part is formed, for example, by removing the clad at the tip of the optical fiber over a predetermined length and attaching light scattering particles such as metal particles to the exposed side surface of the core together with a transparent resin such as acrylic. be.

JP 2018-79136 A

In forming a light scattering member containing a large number of light scattering particles around the core exposed from the clad, the present inventors applied a liquid thermosetting resin in which the light scattering particles were dispersed and mixed to the tip surface of the core. And, after adhering to the outer peripheral surface, the method of heating and curing the thermosetting resin was devised. However, although this method can reduce the cost, the light scattering member covering the tip surface of the core becomes thick, as in a comparative example (see FIG. 7) described later, and the amount of light emitted from this portion increases. There was a problem.

Therefore, the present invention suppresses an excessive amount of the light scattering member covering the tip surface of the core, and increases the intensity of light in the radial direction of the core in the range where the light scattering member is formed in the longitudinal direction of the optical fiber. It is an object of the present invention to provide a peripheral surface emitting linear light guide capable of improving the uniformity of the light, and a method for manufacturing the same.

An object of the present invention is to solve the above problems by providing an optical fiber in which a core is exposed from the clad at one end in the longitudinal direction, and at least a portion of the outer peripheral surface of the core exposed from the clad is replaced by the core. and a light scattering member covering a predetermined axial length range together with the tip surface, wherein the light emitted from the core is scattered and emitted by the light scattering member, wherein the core is The peripheral surface emitting linear light guide is provided, wherein the tip end surface of is a convex curved surface.

In order to solve the above problems, the present invention also provides a manufacturing method for manufacturing the peripheral surface emitting linear light guide, wherein the clad at the end of the optical fiber is removed to remove the core. a surface forming step of convexly curving the end surface of the core; and a light scattering member forming step of forming the light scattering member around the core. A method for manufacturing a peripheral surface emitting linear light guide, wherein the tip end portion of the core is heated to melt and then cooled to harden, thereby forming the tip end surface of the core into a convex curved surface.

According to the peripheral surface emitting linear light guide and the method for manufacturing the same according to the present invention, the amount of the light scattering member covering the tip surface of the core is suppressed from becoming excessive, and the light scattering member is prevented from becoming too large in the longitudinal direction of the optical fiber. It is possible to improve the uniformity of light intensity in the radial direction of the core in the formed range.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a treatment apparatus having a catheter configured using a circumferentially emitting linear light guide according to an embodiment of the present invention together with a patient to be treated. FIG. 4 is a schematic diagram showing the distal end of a catheter inserted into a patient's body; (a) is a perspective view showing one end of a peripheral surface emitting linear light guide. (b) is a cross section along the line AA of (a) along the axial direction of the peripheral surface emitting linear light guide. (c) is a BB line cross section of (a) along the axial direction of the peripheral surface emitting linear light guide. (a) to (c) are explanatory diagrams showing an exposure step in the method of manufacturing an optical fiber. (d) is an explanatory diagram showing a curved surface forming step in the method of manufacturing an optical fiber. (a) to (d) are cross-sectional views showing each stage of a light scattering member forming step in the method of manufacturing an optical fiber. (e) is a cross-sectional view showing a state in which a protective coating layer is formed on the outer circumference of the light scattering member. (a) and (b) are schematic configuration diagrams showing a light scattering layer forming apparatus for forming first to fourth light scattering layers. FIG. 10 is a cross-sectional view showing a peripheral surface emitting linear light guide according to a comparative example; It is explanatory drawing which shows the measuring method which measures the light intensity distribution in the axial direction of the peripheral surface emitting linear light guide which concerns on embodiment, and the peripheral surface emitting linear light guide which concerns on a comparative example. 5 is a graph showing the light intensity distribution of peripheral surface emitting linear light guides according to the embodiment and the comparative example. (a) to (d) are cross-sectional views showing modifications.

[Embodiment]
FIG. 1 is a schematic diagram showing a treatment apparatus 1 using a circumferential surface emitting linear light guide 3 as a catheter together with a patient P to be treated according to an embodiment of the present invention. The treatment apparatus 1 has a main body 2 and a peripheral surface emitting linear light guide 3 , and the distal end portion of the peripheral surface emitting linear light guide 3 is inserted into the patient P's body. The main body 2 has a light source 21 that emits laser light, and the laser light generated by the light source 21 is incident on the proximal end portion of the peripheral surface emitting linear light guide 3 .

<Structure of Peripheral Light Emitting Linear Light Guide>
FIG. 2 is a schematic diagram showing the distal end portion of the circumferential surface emitting linear light guide 3 inserted into the body of the patient P. As shown in FIG. In FIG. 2, a portion of the blood vessel _P1 of the patient P is cut away to show the distal end portion of the peripheral surface emitting linear light guide 3 inserted into the blood vessel _P1 . The laser light Lr scattered and radiated from the peripheral surface emitting linear light guide 3 irradiates the treatment area _P2 and reacts the drug contained in the treatment area _P2 in advance. Thus, intravascular laser therapy is performed.

FIG. 3(a) is a perspective view showing one end of the peripheral surface emitting linear light guide 3. FIG. FIG. 3(b) is a cross section taken along the line AA of FIG. 3(a) along the axial direction of the peripheral surface emitting linear light guide 3. FIG. FIG. 3(c) is a cross section taken along the line BB of FIG. 3(a) along the axial direction of the peripheral surface emitting linear light guide 3. FIG.

The circumferential surface emitting linear light guide 3 includes an optical fiber 4 that guides the laser light generated by the light source 21 to the treatment site _P2 , a light scattering member 5 provided at one end of the optical fiber 4, and a light scattering member 5. and a protective coat layer 6 covering the The optical fiber 4 has a core 41 , a clad 42 and a sheath 43 . At one end in the longitudinal direction of the optical fiber 4, as shown in FIG. there is

The light scattering member 5 covers the entire circumference of the outer peripheral surface 41 a of the core 41 exposed from the clad 42 over a predetermined axial length range, and also covers the tip surface 41 b of the core 41 . The axial length of the portion of the core 41 where the outer peripheral surface 41a is covered with the light scattering member 5 is, for example, 1 to 5 cm. A part of the core 41 in the longitudinal direction is an uncovered portion 415 that is not covered with the clad 42 or the light scattering member 5 . The protective coat layer 6 is light transmissive and covers the light scattering member 5 , the uncovered portion 415 of the core 41 , and the clad 42 exposed from the sheath 43 .

The tip surface 41b of the core 41 is convexly curved in a curved surface forming step in the method of manufacturing the circumferential surface emitting linear light guide 3, which will be described later. Here, the front end surface 41b of the core 41 refers to the surface of the core 41 within a range that can be seen when the core 41 made into a straight line is viewed from the axial direction along the center line C thereof. In addition, being convex means that the tip end surface 41b of the core 41 is larger in the axial direction toward the center than the cut surface (plane) when the core 41 is cut perpendicularly to the center line C. It means that it has a protruding convex curved surface. In this embodiment, as shown in FIGS. 3(b) and 3(c), the tip surface 41b of the core 41 is hemispherical.

In this embodiment, the core 41 is made of quartz glass and the clad 42 is made of polymer. The sheath 43 is a fluororesin, more specifically ETFE (ethylenetetrafluoroethylene copolymer). The diameter of core 41 is, for example, 200 μm. The refractive index of the core 41 is higher than that of the clad 42 , and the light propagating through the core 41 within the clad 42 is totally reflected at the interface with the clad 42 . 3A and 3B, the thickness of the core 41 and the thickness of the light scattering member 5 are exaggerated.

The light scattering member 5 scatters and radiates light emitted from the outer peripheral surface 41 a and the tip end surface 41 b of the core 41 . The light scattering member 5 is formed by dispersing and mixing a large number of light scattering particles 500 in a light transmissive base material 50 having a higher refractive index than the core 41 . Here, being dispersed and mixed means that the light scattering particles 500 are mixed so as to be evenly dispersed in the base material 50 so that the light scattering particles 500 do not clump together in a part of the base material 50 . It means that there is In this embodiment, the base material 50 is a thermosetting resin. The light scattering particles 500 are particles too small to be recognized by the naked eye, but the size of the light scattering particles 500 is exaggerated in FIG. 3(c).

The base material 50 has a higher refractive index than the core 41 , and the light emitted from the outer peripheral surface 41 a and the tip end surface 41 b of the core 41 enters the light scattering member 5 . In this embodiment, the base material 50 is made of silicone resin and has a refractive index of 1.52, for example. The refractive index of the core 41 is, for example, 1.46. The refractive index of the protective coat layer 6 is the same as or higher than the refractive index of the base material 50 of the light scattering member 5 .

The light scattering particles 500 are metal particles that reflect light incident on the light scattering member 5 . In this embodiment, titanium oxide (TiO ₂ ) is used as the light scattering particles 500 . However, the light scattering particles 500 may be aluminum oxide (alumina), fine metal powder of silver, copper, iron, or alloys thereof.

The light scattering member 5 has a multi-layered structure composed of a plurality of layers, and at least a portion of the plurality of layers overlap in the radial direction of the core 41 . In the present embodiment, the number of layers of the light scattering member 5 is four, and four layers overlap in the radial direction on the outer peripheral surface 41 a and the tip surface 41 b of the tip portion 410 of the core 41 . These four layers are hereinafter referred to as a first light scattering layer 51, a second light scattering layer 52, a third light scattering layer 53, and a fourth light scattering layer 54 in order from the inside.

As shown in FIG. 3C, the thicknesses _t 1 to t 4 of the first to fourth light scattering layers 51 to 54 laminated around the outer peripheral surface 41a of the tip 410 of the core ₄₁ are the same. be. Each of t ₁ to t ₄ is, for example, 5 to 10 μm. Incidentally, the thickness t ₅ of the protective coat layer 6 is the same as t ₁ to t ₄ as an example, but may be different from t ₁ to t ₄ .

As shown in FIG. 3B, the axial length range E of the core 41 covered with the light scattering member 5 is divided into first to fourth regions 411 according to the number of layers (4 in this embodiment). 414, in the first region 411 closest to the distal end of the core 41 including the distal end surface 41b, the first to fourth light scattering layers 51 to 54 are formed on the outer peripheral surface 41a and the distal end surface 41b of the core 41. In the fourth region 414 closest to the clad 42 , only the fourth light scattering layer 54 is formed on the outer peripheral surface 41 a of the core 41 . In a second region 412 adjacent to the first region 411, second to fourth light scattering layers 52 to 54 are formed on the outer peripheral surface 41a of the core 41, and a third light scattering layer adjacent to the fourth region 414 is formed. In the region 413 of , the third and fourth light scattering layers 53 and 54 are formed on the outer peripheral surface 41a of the core 41 .

Due to this multilayer structure, the radial thickness of the light scattering member 5 on the outer peripheral surface 41 a of the core 41 gradually increases toward the tip portion 410 side of the core 41 . Also, the amount of light scattering particles 500 in the outer circumference of the core 41 gradually increases toward the tip portion 410 side of the core 41 .

The outer peripheral surface 41a and the tip surface 41b of the core 41 and the innermost layer among the first to fourth light scattering layers 51 to 54 in the first to fourth regions 411 to 414 are in close contact with each other without gaps. ing. As shown in FIG. 3C, the total thickness (average value) of the light scattering member 5 formed on the outer peripheral surface 41a of the core 41 in the first region 411 _{is ta} , and the light scattering member on the tip surface 41b When the total thickness of 5 (maximum value at the central portion) is _tb , _tb is thicker than _ta and less than twice _ta . That is, t _a and t _b satisfy the relational expression t _a <t _b <2t _a . In order to improve the uniformity of the light intensity in the radial direction of the core 41, it is desirable that _tb be close to _ta .

In this embodiment, the mixing ratio of the light scattering particles 500 to the base material 50 is different for each of the first to fourth light scattering layers 51 to 54 . When the concentrations of the light scattering particles 500 in the first to fourth light scattering layers 51 to 54 are C ₁ to C ₄ respectively, the concentration C ₁ of the first light scattering layer 51 is, for example, 20 mg/ml, and that of the second light scattering layer 51 is 20 mg/ml. The concentration _C2 of the light scattering layer 52 is, for example, 10 mg/ml, the concentration _C3 of the third light scattering layer 53 is, for example, 0 mg/ml, and the concentration _C4 of the fourth light scattering layer 54 is, for example, 7 mg/ml. That is, in the present embodiment, the concentrations C 1 to C 4 of the light scattering particles 500 in the first to fourth light scattering layers 51 to ₅₄ have a relationship of _{C 1 >} C ₂ >C ₄ >C ₃ .

In the above example, the concentration _C3 of the third light scattering layer 53 is 0 mg/ml, and the third light scattering layer 53 does not contain the light scattering particles 500. 53 may include light scattering particles 500 . Moreover, although the case where the number of layers of the light scattering member 5 is four has been described here, the number of layers of the light scattering member 5 is not limited to four, and may be two, three, or five or more. Furthermore, the light scattering member 5 is not limited to a multilayer structure, and may have a single layer structure in which the mixing ratio of the light scattering particles 500 to the base material 50 is uniform.

<Manufacturing Method of Peripheral Light Emitting Linear Light Guide 3>
Next, a method for manufacturing the peripheral surface emitting linear light guide 3 will be described. The manufacturing method of the circumferential surface emitting linear light guide 3 includes an exposing step of removing the clad 42 at the end of the optical fiber 4 to expose the core 41, and a curving step of convexly curving the tip surface 41b of the core 41. and a light scattering member forming step of forming the light scattering member 5 around the core 41 .

4A to 4C are cross-sectional views showing the exposure process. In this exposure step, as shown in FIG. 4A, an optical fiber 4 having a core 41, a clad 42, and a sheath 43 is prepared, and as shown in FIG. remove over Thereafter, as shown in FIG. 4C, the clad 42 exposed from the sheath 43 is removed over a predetermined length range to expose the core 41 from the clad 42, and the exposed portion of the core 41 is cut. As a method for cutting the core 41, for example, a cutting tool 91 is used to scratch a portion of the core 41, and the core 41 is broken at the scratched portion. A cut surface 41 c of the cut core 41 is planar and perpendicular to the longitudinal direction of the optical fiber 4 .

FIG. 4(d) is a cross-sectional view showing a state in which the cut surface 41c of the core 41 is convexly curved to form a convex curved distal end surface 41b. In the curved surface forming step, the periphery of the cut surface 41c of the core 41 is heated to be melted into a liquid state, and then cooled to harden. A portion of the core 41 that has been liquefied by heating naturally assumes a hemispherical shape due to surface tension, and then becomes a solid with that shape by cooling. A specific method for heating the core 41 is not particularly limited, but heating can be performed by arc discharge, for example. Moreover, cooling can be performed by natural cooling, for example.

5A to 5D are cross-sectional views showing each stage of the light scattering member forming process. In the light scattering member forming step, as shown in FIGS. 5A and 5B, after forming the first light scattering layer 51 on the outer peripheral surface 41a and the tip end surface 41b of the first region 411 of the core 41, A second light scattering layer 52 is formed outside the outer peripheral surface 41 a and the first light scattering layer 51 in the second region 412 of the core 41 . After that, as shown in FIGS. 5(c) and (d), the second light scattering layer 52 is formed outside the outer peripheral surface 41a and the second light scattering layer 52 in the third region 413 of the core 41. , the fourth light scattering layer 54 is formed outside the outer peripheral surface 41 a and the third light scattering layer 53 in the fourth region 414 of the core 41 .

Further, after sequentially forming the first to fourth light scattering layers 51 to 54 around the core 41, as shown in FIG. A protective coat layer 6 is formed so as to cover the portion of the clad 42 exposed from the sheath 43 .

6A and 6B are schematic configuration diagrams showing a light scattering layer forming apparatus 7 for forming the first to fourth light scattering layers 51 to 54. FIG. In FIGS. 6A and 6B, the vertical direction corresponds to the vertical direction. The light scattering layer forming device 7 includes a base plate 71 , a support 72 erected perpendicularly to the base plate 71 , a lift table 73 vertically movable with respect to the support 72 , and a holder for holding the optical fiber 4 . 74 and a heater 75 fixed to the post 72 .

The lift table 73 is vertically moved with respect to the column 72 by an actuator (not shown). As this actuator, for example, an actuator configured to convert rotation of an electric motor into linear motion by a ball screw or the like can be used. The lift table 73 has a support portion 731 that supports the holder 74 , and the holder 74 is supported by the support portion 731 .

The holder 74 vertically holds the portion of the optical fiber 4 covered with the sheath 43 over a predetermined length range. Thereby, in the arrangement step, the core 41 protruding from the end of the clad 42 is arranged so as to droop downward in the vertical direction. The holder 74 moves vertically together with the lift table 73 while holding the optical fiber 4 .

The heater 75 has an insertion hole 750 through which the optical fiber 4 is vertically inserted. A cylindrical radiation member 751 that emits infrared rays is arranged around the insertion hole 750 . When the radiation member 751 is heated by the heating wire 752 , the infrared rays are emitted into the insertion hole 750 . Thereby, it is possible to uniformly heat the periphery of the core 41 of the optical fiber 4 from all directions. The radiation member 751 and the heating wire 752 are housed in a case member 753 , and the case member 753 is connected to the post 72 by a connecting arm 754 .

The first to fourth light scattering layers 51 to 54 are formed by attaching a plurality of types of liquid materials (first to fourth liquid materials 811 to 814) having different mixing ratios of the light scattering particles 500 around the core 41, It is formed by curing. The first liquid 811 becomes the first light scattering layer 51 by curing, and the second liquid 812 becomes the second light scattering layer 52 by curing. Further, the third liquid 813 becomes the third light scattering layer 53 by curing, and the fourth liquid 814 becomes the fourth light scattering layer 54 by curing.

In the first to fourth liquid bodies 811 to 814, a large number of light scattering particles 500 are dispersed and mixed in the liquid base material 50L before curing. The liquid base material 50</b>L is liquid at room temperature before the heating step, and is cured by being heated by the heater 75 to become the solid base material 50 . The concentrations of the light scattering particles 500 in the first to fourth liquid bodies 811 to 814 are concentrations according to the above relationship of C ₁ >C ₂ >C ₄ >C ₃ .

The first to fourth liquid substances 811 to 814 are contained in first to fourth containers 821 to 824, respectively. The first to fourth containers 821 to 824 are cup-shaped with an open top. In FIG. 6A, the first to fourth containers 821 to 824 are shown in cross section, and the first to fourth liquid bodies 811 to 814 inside them are shown. 6A and 6B show a state in which the second container 822 is mounted on the mounting surface 71a of the base plate 71 below the heater 75. FIG. On the mounting surface 71a of the base plate 71, first to fourth liquid materials 811 to 814 are sequentially mounted according to the stage of the light scattering member forming process.

In the light scattering member forming process, the core 41 is partially moved below the liquid surfaces of the first to fourth liquid materials 811 to 814 by moving the lift table 73 downward. are pulled up from the first to fourth liquid materials 811 to 814 and heated by the heater 75 . The liquid base material 50L is viscous, and when the lift table 73 moves upward, the core 41 is pulled up while the base material 50L adheres to the surroundings due to the viscosity. FIG. 6A shows a state in which the core 41 is being lifted upward from the liquid surface 812a of the second liquid 812. FIG.

When curing the base material 50L, as shown in FIG. 6B, the lift table 73 is raised until the core 41 exposed from the clad 42 is positioned within the insertion hole 750 of the heater 75, and the first to first 4 liquid materials 811 to 814 are heated by infrared rays emitted from the radiation material 751 to be cured. The first to fourth liquid materials 811 to 814 flow slightly vertically downward due to their own weight during the period from when they are pulled up from the first to fourth containers 821 to 824 until they harden. _tb becomes thicker than _ta .

After that, a protective coating layer 6 is further formed to obtain the peripheral surface emitting linear light guide 3 . The protective coat layer 6 may be formed, for example, in the same manner as the first to fourth light scattering layers 51 to 54, but the protective coat layer 6 is formed by a method different from that for the first to fourth light scattering layers 51 to 54. may be formed.

<Structure of Peripheral Light Emitting Linear Light Guide 3A According to Comparative Example>
FIG. 7 is a cross-sectional view showing a peripheral surface emitting linear light guide 3A according to a comparative example. This circumferential surface emitting linear light guide 3A includes an optical fiber 4 having a core 41 partially exposed from a clad 42, like the circumferential surface emitting linear light guide 3 according to the above embodiment. , the light scattering member 5A in which a large number of light scattering particles 500 are dispersed and mixed is formed around the core 41, but the tip surface of the core 41 is not convexly curved, and the cutting perpendicular to the longitudinal direction is performed. The surface 41c remains as it is. Further, unlike the light scattering member 5 according to the above embodiment, the light scattering member 5A has a single layer structure in which the mixing ratio of the light scattering particles 500 is uniform throughout. The light scattering member 5A is covered with a protective coat layer 6A.

The light scattering member 5A of the peripheral surface emitting linear light guide 3A is, like the light scattering member 5 of the peripheral surface emitting linear light guide 3 according to the embodiment, a liquid material in which a large number of light scattering particles are dispersed and mixed. is adhered to the core 41, and then the base material is cured by heating. Formed in a hemispherical shape. Therefore, the light scattering member 5A covering the cut surface 41c of the core 41 is thick.

<Light Intensity Distribution of Peripheral Light Emitting Linear Light Guides 3, 3A According to Embodiment and Comparative Example>
FIG. 8 is an explanation showing a measuring method for measuring the light intensity distribution in the axial direction of the peripheral surface emitting linear light guide 3 according to the above embodiment and the peripheral surface emitting linear light guide 3A according to the comparative example. It is a diagram. FIG. 8 shows the state during measurement of the peripheral surface emitting linear light guide 3 as an example, but the light intensity distribution is similarly measured for the peripheral surface emitting linear light guide 3A according to the comparative example. .

In this measurement method, the laser light Lr generated by the light source 21 is made incident on the core 41 from the base end portion 4a of the optical fiber 4, The intensity of the radially emitted light is measured by an optical power meter 92 . During measurement, the optical power meter 92 is moved in the X direction parallel to the core 41, and the intensity of light is measured at a plurality of positions in the X direction.

7 and 8, _X0 indicates the position in the X direction of the portion where the core 41 is exposed from the clad 42 (the end of the clad 42). _X1 indicates the position of the end of the light scattering member 5, 5A on the clad 42 side in the X direction. X ₂ is the position of the tip end of the core 41 in the X direction (the position of the vertex _41b0 of the tip surface 41b of the core 41 in the peripheral surface emitting linear light guide 3 and the position of the peripheral surface emitting linear light guide 3A position of the cut surface 41c of the core 41). Also, _X3 indicates the position of the end of the light scattering member 5, 5A on the side opposite to the clad 42 side in the X direction.

FIG. 9 is a graph showing the light intensity distribution of the peripheral surface emitting linear light guides 3 and 3A, where the horizontal axis indicates the position in the X direction and the vertical axis indicates the light intensity measured by the optical power meter 92. ing.

As shown in FIG. 9, in the range in the X direction between _X1 and _X2 , the difference between the maximum value and the minimum value of the light intensity of the peripheral surface emitting linear light guide 3 according to the embodiment is The difference between the maximum value and the minimum value of the light intensity of the peripheral surface emitting linear light guide 3A according to the comparative example is smaller, and the uniformity of the light intensity is higher. It is considered that this is due to the following reasons.

Light emitted from the outer peripheral surface 41a of the core 41 and incident on the light scattering members 5, 5A passes through the base material 50 without hitting the light scattering particles 500, and reaches the interface between the protective coating layers 6, 6A and the atmosphere. Then, there is a large proportion of the light reflected at this interface and incident on the core 41 again. This is because the light propagating through the core 41 from the light source 21 has a shallow angle with respect to the axial direction of the core 41 . However, when the light incident on the light scattering members 5 and 5A strikes the light scattering particles 500, the light scattering particles 500 scatter this light, and the scattered light scatters at a relatively large angle at the interface between the protective coating layers 6 and 6A and the atmosphere. hit. Accordingly, the scattered light scattered by the light scattering particles 500 is easily radiated to the outside from the light scattering members 5, 5A and the protective coating layers 6, 6A.

In the peripheral surface emitting linear light guide 3A according to the comparative example, the thickness of the light scattering member 5A covering the outer peripheral surface 41a of the core 41 and the mixing ratio of the light scattering particles 500 are uniform throughout the axial direction. The light intensity distribution measured by the meter 92 roughly matches the intensity distribution of the light incident on the light scattering member 5A from the core 41. FIG. The light emitted from the outer peripheral surface 41a of the core 41 reaches a maximum when it slightly exceeds the position of _X1 toward the _X2 side in the X direction, and then gradually weakens as it propagates through the core 41. Therefore, light scattering Similarly, the intensity of the light emitted from the member 5A gradually decreases.

On the other hand, in the peripheral surface emitting linear light guide 3 according to the embodiment, the amount of the light scattering particles 500 on the outer periphery of the core 41 is small at the outer periphery of the fourth region 414, and the third region 413 and the second region 412 , the number gradually increases at the outer periphery of the first region 411 . Therefore, the light emitted from the outer peripheral surface 41 a of the fourth region 414 of the core 41 toward the light scattering member 5 is likely to be reflected at the interface between the protective coat layer 6 and the atmosphere and return to the core 41 . On the other hand, the light emitted from the outer peripheral surface 41 a of the first region 411 of the core 41 toward the light scattering member 5 hits the light scattering particles 500 , is reflected, and is likely to be emitted to the outside of the protective coat layer 6 . That is, in the peripheral surface emitting linear light guide 3, the balance between the intensity of the light in the core 41 and the ease of radiation to the outside of the light scattering member 5 and the protective coating layer 6 results in a difference between _X1 and _X2 . A flat light intensity distribution is obtained in the range in the X direction between.

Further, as shown in FIG. 9, in the vicinity of _X2 , the light intensity of the peripheral surface emitting linear light guide 3A according to the comparative example is extremely high. This is because, in the peripheral surface emitting linear light guide 3A according to the comparative example, internal reflection is less likely to occur at the cut surface 41c of the core 41, and the thickness of the light scattering member 5A covering the cut surface 41c is large. This is because most of the light emitted from the cut surface 41 c is emitted to the outside of the light scattering member 5</b>A and the protective coat layer 6 .

On the other hand, in the peripheral surface emitting linear light guide 3 according to the embodiment, an extreme increase in light intensity in the vicinity of _X2 is suppressed. This is because, in the peripheral surface emitting linear light guide 3 according to the embodiment, the outer surface of the light scattering member 5 at the tip portion in the longitudinal direction is hemispherical, but the tip surface 41b of the core 41 is also hemispherical. Therefore, the portion of the light scattering member 5 that covers the tip surface 41b of the core 41 is relatively thin.

(Actions and effects of the embodiment)
According to the embodiment described above, it is possible to prevent the amount of the light scattering member 5 covering the tip surface 41b of the core 41 from becoming excessive, and the light scattering member 5 is formed in the longitudinal direction of the optical fiber 4. It is possible to improve the uniformity of the light intensity in the radial direction of the core 41 in the range. As a result, for example, when the peripheral surface emitting linear light guide 3 is used for treatment of an affected area as shown in FIG. 2, the accuracy and safety of treatment can be improved.

(Modification)
10A to 10C are sectional views showing modifications of the shape of the tip portion 410 of the core 41. FIG. FIG. 10(d) is a cross-sectional view showing a modification in which a light scattering member 5B having a single-layer structure is formed on the outer peripheral surface 41a and the tip end surface 41b of the core 41 of the optical fiber 4 according to the above embodiment.

The present invention is not limited to having a regular hemispherical shape, and the present invention can achieve the above effects as long as the tip surface 41b of the core 41 has a convex curved shape. Here, the term “regular hemispherical shape” means that the entire tip surface 41b is a convex curved surface having a radius of curvature half the diameter of the core 41 . In FIGS. 10(a) to 10(c), the shape of the core 41 having a regular hemispherical tip surface is indicated by an imaginary line L. As shown in FIG. 10(a) shows a case where the tip surface 41b of the core 41 protrudes in the axial direction from the imaginary line L, and FIG. It shows the case where it does not protrude. Also, FIG. 10(c) shows a case where the diameter _D1 of the tip portion 410 of the core 41 including the tip surface 41b is larger than the diameter _D2 of the core 41 before performing the curving process. .

Even if the core 41 has a shape as shown in FIGS. It becomes possible to improve the uniformity of the light intensity in the direction. In addition, as shown in FIG. 10(c), when the diameter _D1 of the tip portion 410 of the core 41 is larger than the diameter _D2 of the core 41 before performing the curving process, the diameter _D1 It is desirable that the outer diameter of the whole when the light scattering member and the protective coating layer are formed on the outer periphery of the portion does not exceed the outer diameter of the sheath 43 .

Further, as shown in FIG. 10(d), even if the light scattering member 5B having a single-layer structure is formed on the outer peripheral surface 41a and the tip end surface 41b of the core 41, the light scattering member covering the tip end surface 41b of the core 41 is not provided. An excessive amount can be suppressed, and the uniformity of the light intensity in the radial direction of the core 41 can be improved as compared with the above comparative example. In the illustrated example of FIG. 10(d), the thickness of the light scattering member 5B covering the outer peripheral surface 41a of the core 41 is uniform. The core 41 may be thicker toward the tip 410 side.

(Summary of embodiment)
Next, technical ideas understood from the embodiments described above will be described with reference to the reference numerals and the like in the embodiments. However, each reference numeral in the following description does not limit the constituent elements in the claims to the members and the like specifically shown in the embodiment.

[1] An optical fiber (4) in which the core (41) is exposed from the clad (42) at one end in the longitudinal direction, and an outer peripheral surface (41a) of the core (41) exposed from the clad (42) a light scattering member (5, 5B) covering at least a part of the core (41) together with the tip surface (41b) of the core (41) over a predetermined axial length range, and the light emitted from the core (41) A circumferential surface emitting linear light guide (3) for scattered radiation by a scattering member (5), wherein the tip surface (41b) of the core (41) is convexly curved. Light body (3).

[2] The radial thickness of the light scattering member (5) on the outer peripheral surface (41a) of the core (3) gradually increases toward the tip (410) side of the core (41). The peripheral surface emitting linear light guide (3) according to the above [1].

[3] The light scattering member (5) is composed of n layers (n is a natural number of 2 or more), and the light scattering member (5) is formed on the tip surface (41b) of the core (42). The number of layers is n, and the number of layers of the light scattering member (5) formed on the outer peripheral surface (41a) of the core (41) increases from the tip (410) side toward the clad (42) side. The peripheral surface emitting linear light guide (3) according to the above [2], which gradually decreases as the number increases.

[4] A manufacturing method for manufacturing the peripheral surface emitting linear light guide (3) according to any one of [1] to [3] above, wherein the clad (4) at the end of the optical fiber (4) 42) is removed to expose the core (41); a surface forming step is to form the tip surface (41b) of the core (41) into a convex surface; a light scattering member forming step of forming a scattering member (5), and in the curving step, the tip (410) of the core (41) is heated to melt and then cooled to harden. A method for manufacturing a peripheral surface emitting linear light guide (3), wherein the tip surface (41b) of the core (41) is convexly curved.

[5] The light scattering member (5) is formed by dispersing and mixing light scattering particles (500) in a thermosetting resin having a refractive index higher than that of the core (41). supports the core (41) so that the tip portion (410) faces vertically downward, and adheres the liquid light scattering member (5) around the core (41) to adhere the light scattering member (5). The method for producing a peripheral surface emitting linear light guide (3) according to the above [4], which is a step of heating and curing the light scattering member (5).

Although the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the scope of claims. Also, it should be noted that not all combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

3... Peripheral light-emitting linear light guide 4... Optical fiber 41... Core 410... Tip parts 411 to 414... First to fourth regions 41a... Outer peripheral surface 41b... Tip surface 42... Clads 5, 5A, 5B... Light Scattering member 50 Base material 50L Liquid base material 500 Light scattering particles 51 to 54 First to fourth light scattering layers 6 Protective coating layer

Claims (5)

An optical fiber in which the core is exposed from the clad at one end in the longitudinal direction, and light scattering that covers at least a part of the outer peripheral surface of the core exposed from the clad together with the tip surface of the core over a predetermined axial length range. A peripheral surface emitting linear light guide in which light emitted from the core is scattered and emitted by the light scattering member,
wherein the tip surface of the core is convexly curved;
Peripheral emitting linear light guide. The radial thickness of the light scattering member on the outer peripheral surface of the core gradually increases toward the tip end of the core.
The peripherally emitting linear light guide according to claim 1. The light scattering member is composed of n layers (n is a natural number of 2 or more), the number of layers of the light scattering member formed on the tip end surface of the core is n, and the light scattering member is formed on the outer peripheral surface of the core. the number of layers of the light-scattering member thus formed gradually decreases from the tip portion side toward the clad side;
The peripherally emitting linear light guide according to claim 2. A manufacturing method for manufacturing the peripheral surface emitting linear light guide according to any one of claims 1 to 3,
an exposing step of removing the cladding at the end of the optical fiber to expose the core;
a curved surface forming step of convexly curving the distal end surface of the core;
a light scattering member forming step of forming the light scattering member around the core;
In the curved surface forming step, the tip end surface of the core is formed into a convex surface by heating and melting the tip portion of the core and then cooling and hardening it.
A method for manufacturing a peripheral surface emitting linear light guide. The light-scattering member is a thermosetting resin having a higher refractive index than the core and light-scattering particles dispersed and mixed,
The light-scattering member forming step includes attaching the liquid light-scattering member around the core while supporting the core so that the distal end faces downward in the vertical direction, and heating the attached light-scattering member. is a step of curing by
5. The method for manufacturing the peripheral surface emitting linear light guide according to claim 4.

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