JP2023131102A - Peripheral surface light emission linear light guide body - Google Patents

Abstract

To provide a peripheral surface light emission linear light guide body capable of enhancing uniformity of intensity of radiated light while suppressing costs.SOLUTION: A peripheral surface light emission linear light guide body 3 includes: an optical fiber 4 in which a core 41 is exposed from a clad 42 at one end in a longitudinal direction; a light scattering member 5 for covering an outer peripheral surface 41a of the core 41 over a predetermined length range including a tip part 411 of the core 41 of the part exposed from the clad 42; and a reflection member 6 fixed to the tip part 411 of the core 41. The reflection member 6 includes a reflection surface 6a for reflecting light radiated from a tip surface 41b of the core 41, the reflection surface 6a being a curved surface protruding toward the tip surface 41b. The reflection member 6 is a sphere with a diameter D1 larger than a diameter D2 of the core 41, and a solder ball, for instance.SELECTED DRAWING: Figure 4

Description

The present invention relates to a circumferential light emitting linear light guide including an optical fiber and a light scattering member.

Conventionally, catheter therapy has been performed, in which an optical fiber catheter equipped with an optical fiber is inserted into a luminal organ such as the esophagus or intestine, or into a blood vessel or the heart, and the affected area is treated using light emitted from the optical fiber catheter. (For example, see Patent Document 1).

The medical illumination system of Patent Document 1 includes a laser light source, an optical waveguide (optical fiber) that guides the laser light emitted from the laser light source, and a diffuser element attached to the distal end of the optical waveguide. The diffuser element has a diffuser base made of a transparent material such as quartz glass, and the diffuser base includes a scattering element that scatters light. The diffuser base has a cylindrical shape with a diameter larger than that of the optical waveguide, and the laser light guided by the optical waveguide enters from one end in the longitudinal direction of the diffuser base. The laser light incident on the diffuser base is scattered by the scattering element and irradiates the treatment target area. The other end of the diffuser base is provided with a reflective surface that reflects the laser light that has passed through the diffuser base in the longitudinal direction and returns it to the diffuser base.

Special Publication No. 2020-534956

In the optical fiber catheter as described above, it is desirable that the intensity of the light emitted laterally has high uniformity in the longitudinal direction in order to improve the accuracy and safety of treatment. However, in the case described in Patent Document 1, for example, when the scattering elements are arranged evenly along the longitudinal direction of the diffuser base, the intensity of the light emitted laterally varies depending on the longitudinal region. In addition, in the device described in Patent Document 1, since the diffuser base has a larger diameter than the optical waveguide, the portion to be inserted into the body of the patient to be treated becomes larger, which may restrict the area to be treated. , the burden on the patient increases. Furthermore, in order to connect the optical waveguide and the diffuser base, an intermediate medium may be required to match the coefficient of thermal expansion in these connection regions, which increases component costs and manufacturing costs.

The present invention has been made in view of the above circumstances, and its purpose is to provide a circumferential light emitting linear light guide that can increase the uniformity of the intensity of emitted light while suppressing costs. Our goal is to provide the following.

In order to solve the above problems, the present invention provides an optical fiber whose core is exposed from a cladding at one end in the longitudinal direction, and a predetermined length range including the tip of the core exposed from the cladding. A light scattering member that covers the outer peripheral surface of the core, and a reflecting member fixed to the tip of the core, the reflecting member having a reflective surface that reflects light emitted from the tip of the core, A circumferential light emitting linear light guide is provided, wherein the reflective surface is a curved surface convex toward the tip surface.

According to the circumferential light emitting linear light guide according to the present invention, it is possible to increase the uniformity of the intensity of emitted light while suppressing costs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a treatment device using a circumferential light-emitting linear light guide as a catheter according to an embodiment of the present invention together with a patient to be treated. It is a schematic diagram which shows a part of peripheral surface emitting linear light guide inserted into the patient's body. FIG. 3 is a perspective view showing one end of a circumferential light-emitting linear light guide. (a) is a cross-sectional view of the peripheral surface emitting linear light guide along the axial direction. (b) is a cross-sectional view of the tip portion in the axial direction of the circumferential light emitting linear light guide. (a) and (b) are explanatory views showing an example of a reflecting member fixing process. (a) and (b) are explanatory views showing an example of a light scattering member forming process.

[Embodiment]
FIG. 1 is a schematic diagram showing a treatment device using a circumferential light-emitting linear light guide as a catheter according to an embodiment of the present invention, together with a patient to be treated. The treatment device 1 has a main body 2 and a circumferential light-emitting linear light guide 3, and the distal end of the circumferential light-emitting linear light guide 3 is inserted into the patient's P 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 base end of the peripheral surface emitting linear light guide 3.

<Configuration of circumferential light emitting linear light guide 3>
FIG. 2 is a schematic diagram showing a part of the circumferential light-emitting linear light guide 3 inserted into the body of the patient P. In FIG. 2, a part of the blood vessel _P1 of a patient P is cut out, and the peripheral surface emitting linear light guide 3 is shown inserted into the blood vessel _P1 . The laser light Lr scattered and emitted from the circumferential emitting linear light guide 3 irradiates the treatment area P ₂ and causes the drug contained in the treatment area P ₂ in advance to react. Intravascular laser treatment is thereby performed.

FIG. 3 is a perspective view showing one end portion of the peripheral surface emitting linear light guide 3. As shown in FIG. FIG. 4(a) is a cross-sectional view of the circumferential light-emitting linear light guide 3 along the axial direction. FIG. 4(b) is a cross-sectional view of the tip portion of the circumferential light-emitting linear light guide 3 in the axial direction.

The circumferential light-emitting linear light guide 3 has an optical fiber 4 that guides the laser light generated by the light source 21 as propagating light to the treatment area _P2 . The optical fiber 4 includes a core 41 that is a light guide, a clad 42 that covers the outer periphery of the core 41, and a sheath 43 that is a protective member that covers the outer periphery of the clad 42. At one end in the longitudinal direction of the optical fiber 4, the cladding 42 is exposed from the sheath 43, and the core 41 is further exposed from the cladding 42.

Further, the peripheral surface emitting linear light guide 3 includes a light scattering member 5 that covers the outer peripheral surface 41a of the core 41 over a predetermined length range including the tip portion 411 of the core 41 exposed from the cladding 42; It includes a reflecting member 6 fixed to the tip 411 and a cylindrical member 7 that accommodates the tip 411 of the core 41 together with at least a portion of the reflecting member 6.

In this embodiment, as an example, core 41 is made of quartz glass, and cladding 42 is made of polymer. The sheath 43 is made of fluororesin, more specifically ETFE (ethylenetetrafluoroethylene copolymer). The diameter of the core 41 is, for example, 200 μm. The refractive index of the core 41 is higher than the refractive index of the cladding 42, and light propagating through the core 41 within the cladding 42 is totally reflected at the interface with the cladding 42. In the portion where the core 41 is exposed from the cladding 42, part of the light propagated through the core 41 is emitted from the outer circumferential surface 41a of the core 41, and another part of the light propagated through the core 41 is emitted from the distal end surface of the core 41. 41b.

The light scattering member 5 scatters and emits the light emitted from the outer peripheral surface 41a of the core 41. The light-scattering member 5 includes a light-transmitting base material 50 having a higher refractive index than the core 41 and a large number of light-scattering particles 500 dispersed and mixed therein. Here, being dispersed and mixed means that the light scattering particles 500 are mixed so as to be evenly dispersed within the base material 50 so that the light scattering particles 500 do not aggregate in a part of the base material 50. It means to be there. In this embodiment, the base material 50 is a thermosetting resin. Although the light scattering particles 500 are so fine that they cannot be recognized with the naked eye, the size of the light scattering particles 500 is exaggerated in FIGS. 4A and 4B.

The base material 50 has a higher refractive index than the core 41, and light emitted from the outer peripheral surface 41a of the core 41 enters the light scattering member 5 and hits the light scattering particles 500. In this embodiment, the base material 50 is a thermosetting silicone resin, and its refractive index is, for example, 1.52. The refractive index of the core 41 is, for example, 1.46. The light scattering particles 500 are metal particles that reflect the light incident on the light scattering member 5. In this embodiment, rutile-type titanium oxide (TiO ₂ ) is used as the light scattering particles 500. However, the light scattering particles 500 are not limited to this, and fine metal powders such as aluminum oxide (alumina), silver, copper, iron, or alloys thereof may be used as the light scattering particles 500.

As shown in an enlarged view in FIG. 4(b), the light scattering member 5 has a multilayer structure, and is constructed by laminating first to fourth light scattering layers 51 to 54. The thickness of each of the first to fourth light scattering layers 51 to 54 is, for example, 5 to 10 μm. The concentrations of light scattering particles 500 in the base material 50 of the first to fourth light scattering layers 51 to 54 may be the same or different. The concentration of the light scattering particles 500 relative to the base material 50 of the first to fourth light scattering layers 51 to 54 is, for example, 0 to 200 mg/mL.

In this embodiment, the lengths of the first to fourth light scattering layers 51 to 54 in the longitudinal direction of the core 41 are different, and the thickness of the light scattering member 5 is changed depending on the position in the longitudinal direction of the core 41. At the tip 411 of the core 41, the four layers of the first to fourth light scattering layers 51 to 54 are laminated, and the thickness of the light scattering member 5 is the thickest. The number of light scattering members gradually decreases, and in a portion near the cladding 42, the light scattering member 5 is not formed on the outer circumferential surface 41a of the core 41. In this way, the thickness T of the light scattering member 5 (see FIG. 4(a)) is thickest at the outer periphery of the tip 411 of the core 41, and gradually increases as it moves away from the tip 411 along the central axis C of the core 41. Become thin. Note that a protective coat layer or a cover member made of a light-transmitting resin may be provided around the outer periphery of the light-scattering member 5.

This hierarchical structure of the light scattering member 5 is designed in consideration of the fact that the intensity of light generated by the light source 21 and propagated through the core 41 becomes weaker toward the tip 411 in the portion of the core 41 exposed from the cladding 42. This is to increase the amount of light scattering particles 500 toward the tip 411 side, thereby increasing the uniformity of the intensity of light emitted from the circumferential light emitting linear light guide 3. In other words, part of the light incident on the light scattering member 5 that reaches the outer surface of the light scattering member 5 without hitting the light scattering particles 500 is internally reflected and enters the core 41 again. By increasing the amount of light scattering particles 500 toward the 411 side, the uniformity of the light intensity in the longitudinal direction of the circumferential light emitting linear light guide 3 can be improved.

The reflective member 6 has a reflective surface 6a that reflects light emitted from the distal end surface 41b of the core 41, and is adhesively fixed to the distal end surface 41b of the core 41 with an adhesive 81 having optical transparency. The reflective surface 6a is a curved surface that is convex toward the distal end surface 41b of the core 41. In this embodiment, the reflecting member 6 is a sphere, and a hemispherical portion of the surface of the reflecting member 6 on the side of the distal end surface 41b of the core 41 serves as a reflecting surface 6a. A back surface 6b of the reflective member 6 opposite to the reflective surface 6a is covered with a light scattering member 5.

In this embodiment, a spherical solder ball made of a low melting point solder alloy containing tin (Sn) is used as the reflective member 6 in consideration of ease of manufacture. More specifically, solder balls for BGA (ball grid array), which is a type of package for integrated circuits such as microprocessors, are used as the reflective member 6. Such solder balls can be manufactured at low cost, for example, by cooling a molten solder alloy by dropping it from a nozzle onto the liquid surface of a coolant.

As the adhesive 81 for fixing the reflective member 6, for example, a thermosetting silicone resin not mixed with light scattering particles can be suitably used. In this embodiment, the same material as the base material 50 of the light scattering member 5 is used as the adhesive 81, and the core 41 and the reflective member 6 are aligned by the surface tension of the liquid adhesive 81 before hardening. After that, the adhesive 81 is cured by heating. As a result, the center point CP of the reflecting member 6 is positioned on the central axis C of the core 41 as shown in FIG. 4(a).

In the hardened state, the adhesive 81 does not protrude beyond the reflective member 6 in the radial direction of the core 41 . That is, when the reflective member 6 is viewed along the central axis C of the core 41, the adhesive 81 does not protrude outward beyond the outer edge of the reflective member 6. This prevents the outer diameter of the circumferential light-emitting linear light guide 3 from increasing due to the adhesive 81. FIGS. 4A and 4B show, as an example, a state in which the adhesive 81 is provided so as not to protrude beyond the outer peripheral surface 41a of the core 41.

In order to ensure a sufficient area of the reflective surface 6a relative to the distal end surface 41b of the core 41, the diameter _D1 of the reflective member 6 is desirably larger than the diameter _D2 of the core 41. Furthermore, if the reflecting member 6 is too large, the diameter of the circumferential emitting linear light guide 3 will increase, so it is desirable that the diameter D ₁ of the reflecting member 6 is less than or equal to twice the diameter D ₂ of the core 41. . When the ratio of the diameter D ₁ of the reflecting member 6 to the diameter D ₂ of the core 41 is R (R=D ₁ /D ₂ ), the ratio R is preferably 1.1 or more and 1.5 or less.

The cylindrical member 7 is a cylindrical metal pipe made of stainless steel, for example, and covers the entire reflective surface 6a of the reflective member 6 as well as the outer periphery of the core 41 over a predetermined length. The inner surface 7a of the cylindrical member 7 is a reflective surface that is glossy and reflects light. A part of the reflected light emitted from the distal end surface 41b of the core 41 and reflected by the reflecting surface 6a of the reflecting member 6 is further reflected by the inner surface 7a of the cylindrical member 7, enters the core 41 again, and is reflected by the cylindrical member 7. It is radiated from the outer circumferential surface 41a of the core 41, which is not covered by the rays. In FIG. 4(b), an example of the course of light propagated through the core 41 is indicated by an arrow.

It is desirable that the length L of the portion of the cylindrical member 7 covering the core 41 be equal to or greater than the diameter _D2 of the core 41. If this length L is less than the diameter _D2 of the core 41, the portion indicated by the symbol P in FIG. This is because the intensity of the light emitted to the outside from the surrounding area (near the area) increases, and the uniformity of the light intensity in the longitudinal direction of the circumferential light emitting linear light guide 3 decreases. Further, in order to ensure the length of the light emitting portion of the circumferential light emitting linear light guide 3 and to prevent the length of the portion of the core 41 exposed from the cladding 42 from becoming longer than necessary, the cylindrical member 7 is attached to the core 41. It is desirable that the length L of the portion covering the core 41 is three times or less the diameter _D2 of the core 41.

The cylindrical member 7 is fixed to the outer periphery of the light scattering member 5 with an adhesive 82. As the adhesive 82, like the adhesive 81 for fixing the reflective member 6, a thermosetting silicone resin can be suitably used. Further, in this embodiment, the outer diameter of the cylindrical member 7 is smaller than the outer diameter of the sheath 43. Thereby, the maximum outer diameter of the circumferential light emitting linear light guide 3 of the portion inserted into the body of the patient P is configured not to be increased by the cylindrical member 7. Note that in this embodiment, the outer diameter of the cylindrical member 7 is larger than the outer diameter of the cladding 42. Thereby, the wall thickness of the cylindrical member 7 does not become too thin, making it easy to manufacture the cylindrical member 7.

<Method for manufacturing circumferential light emitting linear light guide 3>
Next, a method for manufacturing the circumferential light-emitting linear light guide 3 will be described. The manufacturing method of the circumferential light-emitting linear light guide 3 includes an optical fiber processing step of removing the cladding 42 at one longitudinal end of the optical fiber 4 to expose the core 41, and removing the core 41 of the portion exposed from the cladding 42. a reflecting member fixing step of adhering and fixing the reflecting member 6 to the tip surface 41b of the reflector 6 with an adhesive 81; a light scattering member forming step of forming a multilayered light scattering member 5; and a step of fixing the cylindrical member 7 with an adhesive 82. and a cylindrical member fixing step.

FIGS. 5A and 5B are explanatory diagrams showing an example of the reflecting member fixing process. In the reflecting member fixing step, as shown in FIG. 5A, the tip end surface 41b of the core 41 is directed vertically downward, and a liquid adhesive 81 is applied to the tip end surface 41b. Thereafter, as shown in FIG. 5(b), the reflective member 6 is brought into contact with the adhesive 81, and the reflective member 6 is centered with respect to the core 41 by the surface tension of the adhesive 81. Thereafter, the reflective member 6 is fixed to the tip 411 of the core 41 by heating and solidifying the adhesive 81. Note that the reflective member 6 may be in contact with the distal end surface 41b of the core 41, but the adhesive 81 is interposed between the distal end surface 41b of the core 41 and the reflective member 6, so that the reflective member 6 is in contact with the distal end surface 41b of the core 41. It does not need to be in direct contact with the surface 41b. However, the minimum distance between the reflective member 6 and the contact surface 41a of the core 41 is desirably smaller than the diameter _D2 of the core 41, and more desirably one-half or less of the diameter _D2 of the core 41.

FIGS. 6A and 6B are explanatory diagrams showing an example of a light scattering member forming process. In the light scattering member forming step, as shown in FIG. 6(a), a liquid material 50L in which a large number of light scattering particles 500 are dispersed and mixed in a liquid base material 50 before hardening is prepared, and the reflective member 6 side is vertically disposed. A portion of the core 41 is immersed in the liquid 50L so as to be directed downward. Thereafter, as shown in FIG. 6(b), the core 41 with the liquid material 50L attached to the outer peripheral surface 41a is pulled up. Furthermore, after that, the base material 50 is cured by heating.

FIGS. 6A and 6B show the state when forming the innermost first light scattering layer 51 among the first to fourth light scattering layers 51 to 54. The light scattering member 5 is formed by forming a first light scattering layer 51 on the outer peripheral surface 41a of the core 41, and then sequentially stacking second to fourth light scattering layers 52 to 54. The lengths of the first to fourth light scattering layers 51 to 54 in the longitudinal direction of the core 41 can be adjusted by changing the length of the core 41 immersed in the liquid 50L. Furthermore, when changing the concentration of the light scattering particles 500 in the first to fourth light scattering layers 51 to 54, the core 41 is immersed in liquid material 50L having different concentrations of the light scattering particles 500.

In the cylindrical member fixing process, for example, the adhesive 82 before solidification is applied to the outer periphery of the light scattering member 5, the cylindrical member 7 is covered, and then the adhesive 82 is heated and hardened. Note that in this embodiment, as shown in FIG. 4(b), a part of the reflecting member 6 protrudes from one end in the longitudinal direction of the cylindrical member 7, but the entire reflecting member 6 extends beyond the cylindrical member 7. may be housed in

(Actions and effects of embodiments)
According to the embodiment described above, the laser light generated by the light source 21 and reaching the distal end surface 41b of the core 41 is diffusely reflected by the reflecting surface 6a of the reflecting member 6, which is a convex curved surface. Thereby, it is possible to prevent the high-intensity laser light emitted from the distal end surface 41b of the core 41 from hitting the inner surface of the blood vessel _P1 of the patient P, and to improve the utilization efficiency of the laser light. The uniformity of the intensity of light emitted from the member 5 can be improved.

Further, in this embodiment, since the reflecting member 6 is a sphere, the reflecting member 6 can be fixed to the tip end 411 of the core 41 without considering the orientation of the reflecting member 6 with respect to the core 41. In particular, in this embodiment, since the reflecting member 6 is a spherical solder ball, it is easy to manufacture and can contribute to cost reduction of the circumferential light emitting linear light guide 3.

Furthermore, in this embodiment, since the reflective member 6 is adhesively fixed to the distal end surface 41b of the core 41 by the adhesive 81 having optical transparency, the core 41 and the reflective member 6 are bonded together by the surface tension of the adhesive 81. It can be aligned and fixed. Furthermore, since the adhesive 81 does not protrude beyond the reflective member 6 in the radial direction of the core 41, it is possible to prevent the adhesive 81 from increasing the outer diameter of the peripheral light emitting linear light guide 3. be done.

Further, in this embodiment, since the back surface 6b of the reflective member 6 is covered with the light scattering member 5, the bonding strength of the reflective member 6 to the core 41 is increased by the light scattering member 5 in addition to the adhesive 81. ing.

Furthermore, in this embodiment, since the cylindrical member 7 accommodates the distal end portion 411 of the core 41 together with at least a portion of the reflective member 6, it is possible to prevent the reflective member 6 from coming off due to hitting the inner surface of the blood vessel _P1 , for example. The cylindrical member 7 also contributes to the heat dissipation of the reflective member 6 whose temperature increases due to the radiant heat of the laser beam. In addition, since the inner surface 7a of the cylindrical member 7 is a reflective surface that reflects light, the utilization efficiency of laser light can be increased, and since the cylindrical member 7 functions as a light shielding member that does not transmit light, the reflective member The light reflected by the reflective surface 6a of 6 is not directly radiated in the radial direction of the core 41, and the uniformity of the light intensity in the longitudinal direction of the circumferential light emitting linear light guide 3 is further improved.

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

[1] An optical fiber (4) in which the core (41) is exposed from the cladding (42) at one end in the longitudinal direction, and the tip (411) of the core (41) in the portion exposed from the cladding (42). a light scattering member (5) that covers the outer circumferential surface (41a) of the core (41) over a predetermined length range, and a reflective member (6) fixed to the tip (411) of the core (41). The reflecting member (6) has a reflecting surface (6a) that reflects light emitted from the tip surface (41b) of the core (41), and the reflecting surface (6a) is connected to the tip surface (41b). ) A circumferential light-emitting linear light guide (3) that is a curved surface convex toward ).

[2] The circumferential light emitting linear light guide according to [1] above, wherein the reflective member (6) is a sphere with a diameter (D ₁ ) larger than the diameter (D ₂ ) of the core (41). (3).

[3] The circumferential light-emitting linear light guide (3) according to [2] above, wherein the reflective member (6) is a solder ball.

[4] Any of the above [1] to [3], wherein the reflective member (6) is adhesively fixed to the tip surface (41b) of the core (41) with a light-transmitting adhesive (81). A circumferential light-emitting linear light guide (3) according to claim 1.

[5] The adhesive (81) does not protrude beyond the reflective member (6) in the radial direction of the core (41), and is subordinate to [2] or [3] [4] The circumferential light-emitting linear light guide (3) described in (3).

[6] The light scattering member (5) is made by dispersing and mixing light scattering particles (500) in a thermosetting silicone resin having a higher refractive index than the core (41). 5) is thickest at the outer periphery of the tip (411) of the core (41) and gradually becomes thinner as it moves away from the tip (411), according to any one of [1] to [5] above. peripheral surface emitting linear light guide (3).

[7] Any one of [1] to [6] above, wherein the back surface (6b) of the reflective member (6) opposite to the reflective surface (6a) is covered with the light scattering member (5). The circumferential light-emitting linear light guide (3) described in (3).

[8] Further comprising a cylindrical member (7) that accommodates the tip end (411) of the core (41) together with at least a portion of the reflective member (6), the inner surface (7a) of the cylindrical member (7) ) is a reflective surface that reflects light, the circumferential light-emitting linear light guide (3) according to any one of [1] to [6] above.

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

Moreover, the present invention can be implemented with appropriate modifications within a range that does not depart from the spirit thereof. For example, in the above embodiment, a case has been described in which the reflecting member 6 is a spherical body, but the reflecting member 6 is not limited to this, and may be, for example, in the shape of a bullet with one end having a convex curved surface. In this case, one end portion of the convex curved surface is opposed to the distal end surface 41b of the core 41. Furthermore, the cylindrical member 7 may be omitted if the intensity of the light reflected by the reflective surface 6a of the reflective member 6 and radiated in the radial direction of the core 41 is within a permissible range. Further, the cylindrical member 7 may be made of any material that does not transmit light, and the inner surface 7a does not need to be a reflective surface that reflects light. Furthermore, in the above embodiment, a case has been described in which the lengths of the first to fourth light scattering layers 51 to 54 of the light scattering member 5 are different, but the lengths of the plurality of light scattering layers are the same. There may be.

3... Circumferential light emitting linear light guide 4... Optical fiber 41... Core 411... Tip portion 41a... Outer peripheral surface 41b... Tip surface 42... Clad 5... Light scattering member 500... Light scattering particles 6... Reflecting member 6a... Reflecting surface 6b...Back surface 7...Cylindrical member 7a...Inner surface 81...Adhesive

Claims (8)

an optical fiber whose core is exposed from the cladding at one end in the longitudinal direction; a light scattering member that covers the outer peripheral surface of the core over a predetermined length range including the tip of the core exposed from the cladding; and a reflective member fixed to the tip,
The reflective member has a reflective surface that reflects light emitted from the tip end surface of the core,
the reflective surface is a curved surface convex toward the tip surface;
Circumferential emitting linear light guide. The reflective member is a sphere with a diameter larger than the diameter of the core.
The peripheral surface emitting linear light guide according to claim 1. the reflective member is a solder ball;
The peripheral surface emitting linear light guide according to claim 2. the reflective member is adhesively fixed to the tip surface of the core with a light-transmitting adhesive;
The circumferential light-emitting linear light guide according to any one of claims 1 to 3. The adhesive does not protrude beyond the reflective member in the radial direction of the core,
The circumferential light-emitting linear light guide according to claim 4 depending on claim 2 or 3. The light scattering member is a thermosetting silicone resin having a higher refractive index than the core and light scattering particles are dispersed and mixed therein,
The thickness of the light scattering member is the thickest at the outer periphery of the tip of the core, and gradually becomes thinner as it moves away from the tip.
The circumferential light-emitting linear light guide according to any one of claims 1 to 5. a back surface of the reflective member opposite to the reflective surface is covered with the light scattering member;
The circumferential light-emitting linear light guide according to any one of claims 1 to 6. further comprising a cylindrical member that accommodates the tip end of the core together with at least a portion of the reflective member,
The inner surface of the cylindrical member is a reflective surface that reflects light.
The circumferential light-emitting linear light guide according to any one of claims 1 to 7.

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