JP2007178778A - Light guide and light irradiation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide which has an exiting end reducible in size when for example outgoing light is converged for use and which facilitates manufacturing as well as having sufficient irradiation intensity, in a light guide with an optical fiber bundle formed by bundling a plurality of optical fibers, and also to provide a light irradiation apparatus containing this light guide. <P>SOLUTION: The light guide includes an optical fiber bundle 2 which is composed of a plurality of optical fibers 10 and which is heat welded at least in the light emitting end face 32 that is an end of a light emission side. In the heat-welded light emitting end face, the center axes 14 of the respective optical fibers, situated on the outer side from the center axis 33 of the optical fiber bundle, are inclined to the center axis of the optical fiber bundle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light guide that transmits light and irradiates an irradiated object, and a light irradiation apparatus including the light guide.

  Conventionally, a light guide has been used as a means for transmitting light emitted from a light emitter such as a laser oscillator or a short arc lamp to an arbitrary position of an irradiated object.

  Such light guides are usually used in the case where an optical fiber strand is used alone or in a case where a plurality of optical fiber strands are bundled and used as an optical fiber bundle. When the beam diameter of light incident on the incident end face is large, an optical fiber bundle in which a plurality of optical fiber strands are bundled is often used (see, for example, Patent Document 1).

As a method for irradiating a predetermined range of an object to be irradiated with light transmitted by such a light guide, a method of providing an optical lens between the exit end of the light guide and the object to be irradiated is generally known. Yes. However, such a method using an optical lens requires a space for providing an optical lens in the vicinity of the light guide emission end, which causes a problem that the light guide emission end is enlarged. It was.
JP-A-4-105784

  Under such circumstances, the present invention makes it possible to reduce the size of the exit end when the emitted light is condensed and used in a light guide that is a bundle of optical fibers formed by bundling a plurality of optical fiber strands. An object of the present invention is to provide a light guide that can be manufactured easily and has sufficient irradiation intensity, and a light irradiation apparatus including the light guide.

To achieve the above object, the present invention provides:
(1) It includes an optical fiber bundle composed of a plurality of optical fiber strands and at least an end portion on the light emission side being heat-sealed,
The center axis at the exit end face of each optical fiber positioned outside the center axis of the optical fiber bundle at the end portion of the heat-sealed optical fiber bundle has an inclination with respect to the center axis of the optical fiber bundle. A light guide, characterized by
(2) The light guide according to (1), wherein an end face shape of the end portion of the heat-sealed optical fiber bundle is a plane perpendicular to the central axis of the optical fiber bundle,
(3) At least a part of the optical fiber strand has an angle θ formed by the central axis of the optical fiber strand and the central axis of the optical fiber bundle at the end on the light emission side,
0 <θ ≦ sin ⁻¹ ((n2 / n1) sin (tan ⁻¹ (R / L)))
[Where R is the distance between the central axis of the optical fiber bundle at the light exit end face and the center axis of each optical fiber strand, L is the distance between the light exit end face and the object to be irradiated, and n1 constitutes the optical fiber strand. N2 is the refractive index of the space outside the optical fiber. ]
The light guide according to the above (2), which is arranged so as to satisfy
(4) The light guide according to (1), wherein an end face shape of the end portion of the heat-sealed optical fiber bundle is a convex shape,
(5) The light guide according to (4), wherein an end surface shape of the end portion of the heat-sealed optical fiber bundle is a spherical shape,
(6) The light guide according to any one of (1) to (5), wherein the optical fiber is composed of one or more selected from quartz, multicomponent glass, and plastic.
(7) A light irradiation device including a light emitting body that emits light and a light guide that irradiates an object to be irradiated with light emitted from the light emitting body, wherein the light guide is any one of the above (1) to (6) A light irradiation device characterized by being a light guide according to claim 1,
(8) The light emitting device according to (7), wherein the light emitter is a laser oscillator, and (9) the light irradiation device according to (7), wherein the light emitter is a short arc lamp. .

  According to the present invention, in a light guide in which a plurality of optical fiber strands are bundled to form an optical fiber bundle, the outgoing end can be reduced in size when the outgoing light is condensed and used, and manufacturing is easy. Thus, it is possible to provide a light guide having sufficient irradiation intensity and a light irradiation apparatus including the light guide.

  Hereinafter, embodiments of a light guide and a light irradiation apparatus according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios in the drawings do not necessarily match those described with numerical values in this specification.

The light guide of the present invention is
An optical fiber bundle comprising a plurality of optical fiber strands and at least an end portion on the light emitting side is thermally fused,
The center axis at the output end face of each optical fiber strand located outside the center axis of the optical fiber bundle at the end portion of the heat-sealed optical fiber bundle has an inclination with respect to the center axis of the optical fiber bundle. It is characterized by that.
Fig.1 (a) is sectional drawing which shows the terminal part structure of the light guide in the 1st embodiment of the light guide of this invention.

  The light guide 1 is composed of an optical fiber bundle 2 composed of a large number of optical fiber strands 10 and a sleeve 20, and after heat-sealing the end portion on the light emitting side, the fused portion is cut at a predetermined position. The light guide terminal portion 30 has a cut surface that is mirror-finished.

  As shown in FIG. 1B, the optical fiber 10 is composed of a core 11 made of high-purity quartz having an outer diameter of 190 μm, a cladding layer 12 having an outer diameter of 200 μm, in which quartz is doped with fluorine, and an ultraviolet curable resin. On the other hand, the sleeve 20 has an outer diameter of 12 mm, an inner diameter of 10 mm, and an overall length that are approximately the same as those of the quartz used in the optical fiber 10, and the thermal expansion coefficient and softening temperature are substantially equal. A 50 mm quartz tube is used.

Next, a method for forming a light emitting end portion in the light guide of FIG. 1A will be described with reference to FIG.
As shown in FIG. 2, about 2000 optical fiber strands 10 in which the coating layer 13 near the end portion is dissolved and removed by a solvent are inserted into the sleeve 20, and then a vacuum device 310 is connected to the distal end portion of the sleeve 20. The intermediate portion of the sleeve 20 in the longitudinal direction is heated with the oxyhydrogen burner 300.

  The oxyhydrogen burner 300 reciprocates in the range of 10 mm along the longitudinal direction X1 axis of the sleeve 20 and rotates along the outer peripheral surface of the sleeve 20 around the central axis 33 of the optical fiber bundle 2 to thereby transmit light. The fiber bundle 2 and the sleeve 20 are heated uniformly.

  At the same time, the vacuum device 310 connected to the tip of the sleeve 20 is operated, and the inside of the sleeve 20 is reduced to a pressure 20 KPa lower than the atmospheric pressure. As a result, the optical fiber strands 10 are softened and fused to each other, and are fused and integrated together with the sleeve 20 contracted in the central axis direction to form the light guide terminal portion 30 having the tapered portion 21 on the outer peripheral surface. .

  Through the above steps, the vertical cross-sectional area with respect to the longitudinal direction of the optical fiber bundle 2 decreases from the non-fused portion toward the fused portion 31, and the optical fiber bundle 2 in the sleeve 20 is connected to each optical fiber strand 10. The central axis 14 of the optical fiber bundle 2 is fixed in a state of being inclined in the direction of the central axis 33 of the optical fiber bundle 2 from the non-fused part to the fused part 31 according to the shape of the taper part 21 and becomes tapered. ing. In addition, since each optical fiber 10 of the fusion part 31 is thermally fused with almost no change in the cross-sectional area, the light that travels in the core leaks to the outside and reduces the light output. Can be suppressed.

  The light emitting end portion of the light guide 1 in the present embodiment cuts the fused portion 31 of the light guide 1 after fusion shown in FIG. 2 at the position of the broken line A, and performs polishing on the cut surface. As shown in FIG. 1A, a light emitting end face 32 perpendicular to the central axis 33 of the optical fiber bundle 2 is formed. Here, the position of the broken line A is the sleeve 20 of the fused portion 31. The outer diameter is set to a position where the outer diameter is about 11 mm.

  As a result, the central axis 14 of the optical fiber 10 has an inclination angle θ1 in the direction of the central axis 33 of the optical fiber bundle 2 at the light emitting end face 32 of the light guide terminal portion 30, as shown in FIG. The inclination angle θ1 is larger as the optical fiber 10 disposed near the outer periphery of the optical fiber bundle 2 and is smaller as it approaches the central axis 33 of the optical fiber bundle 2. The central axis 14 of the nearby optical fiber is substantially parallel to the central axis 33 of the optical fiber bundle 2 in the light guide terminal portion 30.

Note that the fusion part 31 is more robust because the fusion between the optical fiber strands 10 is closer to the area closer to the center of the area heated by the oxyhydrogen burner 300. In such a region, the boundary between the core 11 and the cladding layer 12 of the optical fiber 10 may become unclear due to softening, and when the light is incident, the incident light is the interface between the core 11 and the cladding layer 12. The light transmission efficiency as a light guide may be reduced.
For this reason, it is preferable that the cutting position of the fused portion 31 is performed at a position closest to the light incident end portion in a range where the optical fiber wires 10 inside the sleeve 20 are fused to each other.
Moreover, when this position is set as the cutting position, a larger inclination angle θ1 of the central axis 14 of the optical fiber can be obtained.

  As described above, the light guide 1 according to the present embodiment performs the heat sealing process on the optical fiber bundle 2 while reducing the pressure inside the sleeve 20, thereby the optical fiber bundle on the light emitting end face 32 of the light guide terminal portion 30. The center axis 14 of the optical fiber 10 positioned outside the center axis 33 of 2 is processed so as to be arranged concentrically with an inclination angle θ1 in the direction of the center axis 33 of the optical fiber bundle 2. Therefore, it is easy to manufacture, and without increasing the size of the converging portion, it is possible to make a light guide in which each optical fiber at the exit end is accurately tilted in the direction of the central axis of the light guide.

  The inclination angle θ1 of the central axis 14 of each optical fiber 10 can be controlled by operating the pressure reducing force of the vacuum pump 310 when it is heated by the oxyhydrogen burner 300 as follows. it can.

  When the angle of the inclination angle θ1 is increased, it is possible to increase the pressure reduction in the sleeve 20, and conversely, when the angle of the inclination angle θ1 is decreased, the pressure reduction in the sleeve 20 is decreased. Thus, since the tapered portion 21 described above becomes gentle, the inclination angle θ1 of the central axis 14 of each optical fiber strand 10 can also be reduced.

  In addition, as a method for fusing the light guide terminal portion 30, in addition to the method using the oxyhydrogen burner described in this embodiment, a method using high-frequency power can be used.

  Further, as a method of forming the tapered portion 21 during the heat-sealing process, the optical fiber bundle 2 of the non-fused portion is placed in the central axis direction together with the sleeve 20 in place of the method of sucking the inside of the sleeve 20 with a vacuum pump. There is also a method of stretching, but in this case, the cross-sectional area at the fused portion of each optical fiber is smaller than that of the non-fused portion, and the light traveling in the core leaks to the outside and the light output is increased. Since there is a risk of reducing the amount, it is necessary to adjust the amount of stretching according to the characteristics of the incident light.

  As shown in FIG. 1A, in the light guide 1 in this embodiment, since the central axis 14 of the optical fiber 10 intersects the light emitting end face 32 with an inclination, the light emitted from the light emitting end face 32 is Depending on the inclination angle θ1 of the central axis 14 of each optical fiber 10, the light is further refracted in the direction of the central axis 33 of the optical fiber bundle 2 and emitted.

Hereinafter, the influence of the refraction of the light emitted from the light emitting end face 32 on the emission angle will be described with reference to FIG.
FIG. 3 is a cross-sectional view showing a direction in which light 51 incident in parallel to the central axis 14 of the optical fiber 10 from the light incident end face 36 of the optical fiber 10 is refracted when emitted from the light outgoing end face 32. is there.

  The light incident end face 36 of the optical fiber 10 in FIG. 3 converges a light incident side end (not shown) of the light guide 1 shown in FIG. Is a plane that is cut perpendicularly to the central axis of the optical fiber and polished, and is orthogonal to the central axis 14 of the optical fiber 10.

As shown in FIG. 3, the light 51 incident perpendicularly to the light incident end face 36 propagates along the central axis 14 of the optical fiber strand 10, and the light emitting end face 32 has the light emitting end face 32 as the emitted light 52. The light is emitted at an angle of refraction angle θ2 with respect to the orthogonal straight line 16.
From the Snell's law, the relationship between the light 51 before emission and the emission light 52 at the light emission end face 32 is as follows:

n1sin θ1 = n2sin θ2

(Where n1 is the refractive index of the core and n2 is the refractive index of the space outside the optical fiber 10)
And the refraction angle θ2 is

θ2 = sin ⁻¹ ((n1 / n2) × sin θ1) Equation 1

Can be represented by
The above formula 1 means that the refraction angle θ2 is approximately multiplied by the refractive index ratio (n1 / n2) of the inclination angle θ1.

  As described above, in the light guide 1 according to the present embodiment, the light emission end face 32 intersects the central axis 14 of the optical fiber strand 10 with an inclination, so that the emitted light 52 from the light emission end face 32 is at this inclination angle θ1. Accordingly, it is inclined in the direction of the central axis 33 of the optical fiber bundle 2 and further refracted in the direction of the central axis 33 of the optical fiber bundle 2 at the light emitting end face 32 and is inclined by θ2 in total. In addition, it is possible to obtain the same effect as when the inclination of the central axis 14 of the optical fiber 10 is further increased.

  Here, the direction of the outgoing light 52 emitted from the light outgoing end face 32 when parallel light enters the light guide 1 in the present embodiment will be described.

FIG. 4A illustrates the emission direction of light emitted from a position 1 mm, 2 mm, 3 mm, and 4 mm away from the center of the optical fiber bundle in the light emission end face 32 in the radial direction.
4B shows the inclination angle θ1 of the optical fiber at each position of the light emitting end face 32, the refraction angle θ2 of the outgoing light 52, and the outgoing light 52 with the central axis 33 of the optical fiber bundle 2. The distance L to the intersecting point is expressed numerically.
From FIG. 4A, it can be seen that the light emitted from each position of the light emitting end face 32 forms a beam waist at a position approximately 20 mm away from the light emitting end face 32.
Here, the distance L is assumed that the emitted light 52 is emitted from the position of the radius R at the light emitting end face 32.

L = R / tan θ2

Therefore, it can be obtained by the following formula 2 in which formula 1 is substituted.

L = R / tan (sin ⁻¹ ((n1 / n2) × sin θ1)) Equation 2

Accordingly, when θ1 of each optical fiber that constitutes the optical fiber bundle 2 is known, the distance L is obtained from the expression 2 to change the object from the optical fiber bundle 2 to the irradiated object (including the condensing lens). The optimum distance for irradiating light can be adjusted.

The above equation 2 is an equation for obtaining the distance L to the point where the outgoing light 52 intersects the central axis 33 of the optical fiber bundle 2 when the inclination angle θ1 of the optical fiber strand is known. In the case where the distance L (including the condensing lens) is known, the optimum inclination angle θ1 of the optical fiber can be obtained from Equation 3.

θ1 = sin ⁻¹ ((n2 / n1) sin (tan ⁻¹ (R / L))) Equation 3

That is, by obtaining the inclination angle θ1 of each optical fiber strand by Equation 3, the inclination of the corresponding optical fiber strand can be adjusted to an optimum angle at the light exit side end of the optical fiber bundle 2. .
In the light guide according to the present invention, the inclination angle θ1 of each optical fiber at the light emitting end face does not necessarily have to be equal to the value obtained by the above equation 3, and the light constituting the optical fiber bundle At least a part of the fiber strand is equal to or less than the value obtained by Equation 3, that is,

0 <θ1 ≦ sin ⁻¹ ((n2 / n1) sin (tan ⁻¹ (R / L))) Equation 4

Even in this range, it is possible to have a function of tilting outgoing light in the direction of the central axis of the optical fiber bundle. It is preferable that 47 to 100% of all the optical fiber strands located outside the central axis 33 of the optical fiber bundle among the optical fiber strands constituting the optical fiber bundle satisfy the above-mentioned formula 4. It is more preferable that% satisfies the above formula 4.

  The relationship between the processed shape applied to the light guide terminal portion 30 of the light guide 1 of the present embodiment and the emission direction of the emitted light 52 from the light emission end face 32 has been described above. The intensity distribution of light emitted from the exit end face when light is incident on the entire light entrance end face of the light guide will be described by comparison with a conventional light guide in which the light exit end is fixed by adhesion processing.

FIG. 5 shows an apparatus configuration for measuring the intensity distribution of light emitted from the light guide.
In this apparatus, the light emitted from the He-Cd laser oscillator 110 is uniformly incident on the light incident end surface 101a of the light guide 101 by the beam expander 150, and the light intensity distribution at a position L apart from the light emitting end surface 101b is obtained. This is a device for measuring, and has a light intensity meter 130 at a light intensity measurement position, and the light intensity meter 130 is moved along the X2 axis perpendicular to the central axis of the light guide 1 to thereby distribute the light intensity. In the following measurements, the light intensity distribution at L = 25 mm was measured.

  FIG. 6 shows the intensity distribution of the emitted light from the light guide measured by the above apparatus. The solid line shows the light guide with the light emitting end face heat-sealed (the optical fiber strand constituting the optical fiber bundle). Among them, about 70% of all the optical fiber strands located outside the central axis of the optical fiber bundle satisfy the above formula 4) showing the intensity distribution of the emitted light when the laser light is incident, The intensity distribution of the emitted light when a laser beam is incident on a conventional light guide having the light emitting end face fixed with an adhesive is shown.

Note that the light incident end face of the light guide having the light emitting end face heat-sealed is fixed by an organic adhesive instead of the heat fusion, and is subjected to planar polishing in the same manner as the light emitting end face.
Further, the conventional light guide has the same structure as the light guide in which the light emitting end face is heat-sealed except that the light emitting end is fixed with an adhesive.

Comparing the light intensity distribution of the light guide 1 in which the light emitting end face is thermally fused to the light emitting end surface represented by the solid line and the light intensity distribution of the conventional light guide in which the light emitting end part is fixed by an adhesive, indicated by the broken line. It can be seen that the light guide having the light emitting end face heat-sealed irradiates a relatively narrow range with little diffusion of the emitted light.
Also, it can be seen that the light intensity of the irradiated central portion is about twice as high as that of the conventional light guide in which the light emitting end face is fixed with an adhesive.

  As described above, according to the light guide of the present embodiment, it is possible to suppress the diffusion of the emitted light without using an optical component such as an optical lens and without increasing the size of the light guide terminal portion, It can be collected on the central axis of the light guide terminal.

  In the present embodiment, the incident light on the light incident surface of the optical fiber is described using light incident parallel to the central axis of the optical fiber bundle. However, the incident light in the light guide of the present invention is However, it is not necessarily limited to the light incident parallel to the central axis of the optical fiber bundle, but is condensed on the light incident surface of the optical fiber bundle or light inclined with respect to the central axis of the optical fiber bundle. Similar effects can be obtained even in the case of light including many angle components.

  FIG. 7 is a cross-sectional view showing the terminal structure of the light guide according to the second embodiment of the light guide of the present invention.

  The light guide end face shape of the light guide in the present embodiment is obtained by subjecting the cut surface after fusion of the optical fiber bundles to a convex shape so as to become a spherical shape 35 having a radius of 50 mm. The wire 10 and the sleeve 20 are the same as those shown in the first embodiment.

By processing the light emitting end face of the light guide into such a shape, the emitted light is refracted in accordance with the curvature of the light emitting end face. Therefore, the light guide having the flat light emitting end face described in the first embodiment is used. Compared with the above, the emitted light can be further condensed at a position closer to the light emitting end face.
The end face shape of the end portion of the optical fiber bundle can be a concave shape as long as the emitted light can be collected in addition to the convex shape.
The processing of the end face shape of the optical fiber bundle end can be performed, for example, by ELID grinding.

In the light guides shown in the first embodiment and the second embodiment, optical fiber strands made of quartz are used, but the light guide of the present invention is light made of multicomponent glass or plastic. Fiber strands can also be used.
In the first embodiment, the laser oscillator is used as the light emitter that emits light. However, the present invention is not limited to this, and the light guide of the present invention is a short arc lamp or halogen lamp as the light emitter. Etc. can also be used.

Next, the light irradiation apparatus of the present invention will be described.
The light irradiation device of the present invention includes a light emitting body that emits light, and a light guide for irradiating an object to be irradiated with light emitted from the light emitting body, and the light guide is the light of the present invention. It is a guide.

FIG. 8 is a diagram showing a first embodiment of the light irradiation apparatus of the present invention.
In this embodiment, the light irradiation device includes a laser oscillator 210 that oscillates laser light, a lens 220 that condenses the laser light, a light guide 230 that transmits the condensed light, and light emitted from the light guide 230. A condensing lens 241 for condensing the irradiation object W and a processing head unit 240 including the condensing lens 241 are configured.

  As the laser oscillator 210, a Q-switched YAG laser that emits ultraviolet light using a flash lamp as an excitation light source is used.

  In this light irradiating device, the light guide 230 is a light guide in which the light emitting end of an optical fiber bundle made of quartz optical fiber is fused, as in the light guide in the first embodiment of the present invention. The light exit end face 230a of the light guide 230 is processed into a planar shape as shown in FIG. 1, and the optical fiber strand at the light exit end has an inclination in the central axis direction of the optical fiber bundle. Yes.

  In the case of using a light guide whose light emission end is processed in this way, the light 250 emitted from the light guide is smaller in output than the light guide whose emission end surface is fixed by an adhesive as usual. Therefore, the condenser lens 241 can also have a small diameter corresponding to the emission angle φ, and the size of the processing head portion 240 can be further reduced.

FIG. 9 is a diagram showing a second embodiment of the light irradiation apparatus of the present invention.
In this embodiment, the light irradiation device includes a light source device 260 having a built-in short arc lamp 261 and a light guide 230 for transmitting light emitted from the light source device 260 to the irradiation object W. It is used for the purpose of irradiating the irradiated object W coated with an ultraviolet curable adhesive installed at a position 25 mm away from the exit end face of the guide 230 with ultraviolet light.

  In this light irradiation device, the light guide 230 is a light guide in which the light emitting end of an optical fiber bundle made of quartz optical fiber strands is fused, as in the light guide in the above-described embodiment of the light irradiation device. As shown in FIG. 1, the optical fiber strand is inclined in the central axis direction of the optical fiber bundle.

In this embodiment, since the light guide that has processed the light emitting end portion is used in this way, the light 250 emitted from the light guide is emitted from the light guide having the light emitting end portion fixed by a conventional adhesive. Compared with the light, the irradiation intensity was about 1.5 times.
For this reason, even if it was a case where emitted light was directly irradiated to a to-be-irradiated object from a light guide, without using an optical lens, the ultraviolet curing adhesive agent was fully hardened.

  As an embodiment of the light irradiation apparatus of the present invention, a laser oscillator and a short arc lamp are used as a light emitter that emits light, but the invention is not limited to this, and a halogen lamp or the like is used as the light emitter. You can also.

  The light guide of the present invention can reduce the size of the emission end when the emitted light is condensed and used, is easy to manufacture, and has sufficient irradiation intensity. It can use suitably for the light irradiation apparatus containing.

It is sectional drawing (a) which shows the terminal part structure of the light guide in a 1st embodiment of the light guide of this invention, and sectional drawing (b) of an optical fiber strand. It is a figure which shows the position A which cut | disconnects and grind | polishes in order to form the fusion | melting method of an optical fiber bundle terminal, and a light-projection end surface. It is a figure which shows the incident light and the emitted light in the optical fiber strand after a light-projection surface process. The figure (a) which shows the direction of each emitted light in the position away from the central axis of the optical fiber bundle, and the numerical value of the distance L from the light emitting end surface to the condensing point at the inclination angle θ1, the refraction angle θ2 at each position. It is a figure (b) which shows data. It is a figure which shows the apparatus for measuring the intensity distribution of the emitted light when a laser beam injects into a light guide. It is a figure which shows intensity distribution of the emitted light when a laser beam injects into a light guide. It is a figure for demonstrating the terminal part structure in the 2nd embodiment of the light guide of this invention. It is a figure which shows the 1st embodiment of the light irradiation apparatus of this invention. It is a figure which shows the 2nd embodiment of the light irradiation apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light guide 2 Optical fiber bundle 10 Optical fiber strand 11 Core 12 Clad layer 13 Covering layer 14 Center axis of optical fiber strand 16 Straight line orthogonal to light emission surface 20 Sleeve 21 Tapered portion 30 Light guide terminal portion 31 Fusion portion 32 Light emitting end face 33 Central axis of optical fiber bundle 35 Spherical surface 36 Light incident end face 101 Light guide 101a Light incident end face 101b Light emitting end face 110, 210 Laser oscillator 130 Light intensity meter 150 Beam expander 260 Light source device

Claims (9)

An optical fiber bundle comprising a plurality of optical fiber strands and at least an end portion on the light emitting side is thermally fused,
The center axis at the exit end face of each optical fiber positioned outside the center axis of the optical fiber bundle at the end portion of the heat-sealed optical fiber bundle has an inclination with respect to the center axis of the optical fiber bundle. Light guide characterized by that.   2. The light guide according to claim 1, wherein an end face shape of the end portion of the heat-sealed optical fiber bundle is a plane perpendicular to the central axis of the optical fiber bundle. At least a part of the optical fiber strand has an angle θ formed by the central axis of the optical fiber strand and the central axis of the optical fiber bundle at the end on the light exit side,
0 <θ ≦ sin ⁻¹ ((n2 / n1) sin (tan ⁻¹ (R / L)))
[Where R is the distance between the central axis of the optical fiber bundle at the light exit end face and the center axis of each optical fiber strand, L is the distance between the light exit end face and the object to be irradiated, and n1 constitutes the optical fiber strand. N2 is the refractive index of the space outside the optical fiber. ]
The light guide according to claim 2, wherein the light guide is disposed so as to satisfy the above.   The light guide according to claim 1, wherein an end face shape of the end portion of the heat-sealed optical fiber bundle is a convex shape.   The light guide according to claim 4, wherein an end face shape of the end portion of the heat-sealed optical fiber bundle is a spherical shape.   The light guide according to any one of claims 1 to 5, wherein the optical fiber is made of at least one selected from quartz, multicomponent glass, and plastic.   A light irradiation apparatus comprising: a light emitter that emits light; and a light guide that irradiates an object to be irradiated with light emitted from the light emitter, wherein the light guide is the light guide according to claim 1. The light irradiation apparatus characterized by being.   The light irradiation apparatus according to claim 7, wherein the light emitter is a laser oscillator.   The light irradiation apparatus according to claim 7, wherein the light emitter is a short arc lamp.

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