JPH08338915A - Optical transmission device - Google Patents

Abstract

(57) [Abstract] [Purpose] Light that allows the optical energy of laser light output from a laser oscillator to be incident on an optical fiber with low loss and transmitted over a specified distance, while also ensuring a sufficient depth of focus in the irradiated object. Get the transmitter. [Structure] An incident optical system including a first lens 4 guides laser light 2 emitted from a laser oscillator 1 to an optical fiber 3. The laser light emitted from the optical fiber 3 is incident on the divergence angle conversion light guide 8, is converted into a smaller divergence angle of a part of the laser light, and is then condensed by the second lens 7 to be irradiated on the irradiation target 6. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission device for transmitting laser light through an optical fiber and irradiating an object to be irradiated.

[0002]

2. Description of the Related Art FIG. 23 is a block diagram showing a conventional optical transmission apparatus disclosed in Japanese Patent Publication No. 2-55157, for example.
In the figure, 1 is a laser oscillator, 2 is an emitted laser beam emitted from the laser oscillator 1, 3 is an optical fiber, 4 is a first lens for collecting the emitted laser beam 2 and making it enter the optical fiber 3, and 6 is an irradiation target. A body 7 is a second lens for irradiating the irradiated object 6 with the emitted laser light 5 emitted from the optical fiber 3.

Next, the operation will be described. The emitted laser light 2 output from the laser oscillator 1 is focused by the first lens 4 and enters the optical fiber 3 from this one end surface. As the first lens 4, a lens having a long focal length f ₁ is used so that the focusing angle 2θ ₁ of the emitted laser light 2 incident on the optical fiber 3 is 8 degrees or less. The emitted laser light 5 emitted from the emission end face of the optical fiber 3 is at a distance a from the emission end face.
Is incident on the second lens 7 provided at the position, is focused by the second lens 7, and is separated by a distance b from the second lens 7.
(However, b / a <1/2) is incident on the irradiated body 6 provided at a distance. In this way, the optical fiber 3
It is possible to efficiently collect the emitted laser beam 5 from the second lens 7 by the second lens 7 having a small diameter and irradiate the irradiated body 6.

In recent years, since this kind of optical fiber 3 can easily and inexpensively transmit the laser light 2 emitted from a light source such as the laser oscillator 1 to a desired position far away, laser processing is started, medical treatment and measurement are performed. It is widely used in
In order for the optical energy of the emitted laser beam 2 output from the laser oscillator 1 to be efficiently incident on the optical fiber 3, the focused spot diameter of the emitted laser beam 2 is set to the optical fiber 3.
Is smaller than the core diameter and the focusing angle 2θ ₁ of the emitted laser light 2 is smaller than the numerical aperture (NA) of the optical fiber. Further, the beam diameter of the emitted laser light 5 from the optical fiber 3 becomes equal to the core diameter,
The divergence angle of the optical fiber 3 is almost equal to the focusing angle of the laser beam 2 emitted from the laser oscillator 1 which is the incident beam.
It is generally well known that the NA of is not exceeded.

[0005]

Since the conventional optical transmission device is configured as described above, the first lens 4 having a long focal length so that the focusing angle 2θ ₁ is 8 degrees or less is used. Therefore, the focused spot diameter becomes large and the optical fiber 3 having a small core diameter cannot be used. Therefore, in order to obtain a large energy density in the irradiated body 6, the second lens 7 is used.
There is a problem that it is impossible to secure a sufficient depth of focus in the irradiated body 6 without making the imaging magnification of No. 3 small.

Further, since the condensing point of the first lens 4 is arranged in the vicinity of the entrance entrance surface of the optical fiber 3, the intensity distribution on the entrance entrance surface of the optical fiber 3 is a Gaussian distribution having the largest axial strength. However, there is a problem that the optical fiber 3 is damaged when the optical energy of the tail of the intensity distribution enters the cladding. In order to prevent this clad incidence, it is necessary to make the focused spot diameter small so that it enters the core diameter of the optical fiber 3 sufficiently. For this purpose, the laser light 2 emitted from the laser oscillator 1 is made into the first lens. Since the light is evenly condensed at 4, the first lens 4 has a problem that a lens having a short focal length must be used.

Further, the second lens 7 is an optical fiber 3
The intensity distribution of the emitted laser light 5 with which the irradiation target 6 is irradiated is limited to that which reflects the intensity distribution at the exit of the optical fiber 3. There was a problem.

The present invention has been made to solve the above-mentioned problems, and the optical energy of the laser light output from the laser oscillator can be incident on the optical fiber with low loss and transmitted over a predetermined distance. An object of the present invention is to obtain an optical transmission device capable of ensuring a sufficient depth of focus in an irradiation target.

Another object of the present invention is to obtain an optical transmission device capable of efficiently irradiating an object to be irradiated with laser light having various intensity distributions without damaging an optical fiber.

[0010]

According to another aspect of the present invention, there is provided an optical transmission device, wherein a spread angle of at least a part of laser light emitted from an optical fiber is converted to a smaller value and the emitted laser light is irradiated onto an object to be irradiated. It is equipped with an irradiation optical system.

An optical transmission device according to a second aspect of the present invention is provided with a first reflecting surface parallel to the optical axis of the laser light emitted from the optical fiber and an optical axis side of the first reflecting surface. The second reflecting surface which is inclined with respect to the axis and the third surface which is the back surface thereof
And a divergence angle conversion light guide path having at least a reflection surface of the.

The optical transmission device according to the invention of claim 3 is the first
And a cylindrical second reflecting member having second and third reflecting surfaces inclined with respect to the optical axis.

An optical transmission device according to a fourth aspect of the present invention is a third optical transmission device.
The refractive index of the medium provided on the optical axis side of the reflection surface of the
Is larger than the refractive index of the medium provided between the second reflecting surface and the second reflecting surface.

An optical transmission device according to a fifth aspect of the present invention is a first optical transmission device.
And a first transparent member having a second reflecting surface, and a second transparent member having a third reflecting surface, and an air layer provided between the first and second transparent members. Is.

An optical transmission device according to a sixth aspect of the present invention comprises a cooling means for flowing a cooling fluid in the air layer.

An optical transmission device according to a seventh aspect of the present invention is provided with a magnifying imaging lens for magnifying and imaging the exit surface of the optical fiber, and the entrance of the divergence angle conversion light guide path is on the magnifying imaging surface of the magnifying imaging lens. The surface is installed.

An optical transmission device according to an eighth aspect of the present invention is an incident angle control for controlling an angle between an optical axis of a laser beam focused by an incident optical system and an optical axis of an optical fiber to be 0 degree or more. It is equipped with means.

An optical transmission device according to a ninth aspect of the present invention is provided with a perforated concave mirror having a long focal length, which is installed at a slight inclination with respect to the optical axis of laser light and has an opening in the center, and a perforated concave surface. An image forming lens for forming an image of the opening of the mirror near the entrance end face of the optical fiber.

An optical transmission device according to a tenth aspect of the present invention is provided with a light energy amount measuring means for measuring the light energy of the reflected light from the peripheral portion of the opening of the perforated concave mirror.

An optical transmission device according to an eleventh aspect of the present invention comprises optical means for changing a divergence angle of a part of laser light output from a light source such as a laser oscillator.

The optical transmission device according to the twelfth aspect of the present invention is a means for converting the divergence angle of the central portion in the cross section of the laser beam to a smaller value.

An optical transmission device according to a thirteenth aspect of the present invention comprises an optical filter for changing the phase distribution of laser light output from a light source such as a laser oscillator.

An optical transmission device according to a fourteenth aspect of the present invention is an optical filter configured to cause a phase difference between a central portion of incident laser light in the cross-sectional direction and other portions.

[0024]

In the optical transmission device according to the invention of claim 1, the divergence angle of at least a part of the laser light emitted from the optical fiber is converted to a smaller value by the irradiation optical system, and the emitted laser light is irradiated onto the object to be irradiated. . This makes it possible to secure a longer depth of focus than before. Therefore, when compared with the same depth of focus, the imaging magnification can be made smaller than before, so when using optical fibers with the same core diameter,
Smaller imaging spots can be obtained. Further, in the case of an imaging spot having the same diameter as the conventional one, it becomes possible to use an optical fiber having a larger core diameter.

In the optical transmission device according to the second aspect of the present invention, when the laser light emitted from the optical fiber is incident on the divergence angle conversion light guide of the irradiation optical system, a part of the light is reflected on the first reflection surface and the second reflection surface. And a plurality of light beams are transmitted through the divergence angle conversion light guide path while the remaining light is reflected by the third reflection surface a plurality of times and transmitted through the divergence angle conversion light guide path. At this time, for example, when the second and third reflecting surfaces are inclined such that the angle of the reflected light transmitted through the first and second reflecting surfaces with respect to the optical axis gradually decreases along the optical axis direction, The divergence angle of the light guided while being reflected between the first reflecting surface and the second reflecting surface is converted to a smaller one and is irradiated onto the irradiation target. Therefore, it is possible to secure a longer depth of focus than before.

In the optical transmission device according to the third aspect of the present invention, since the first and second reflecting members of the divergence angle converting light guide path are cylindrical, the distance between the first reflecting surface and the second reflecting surface is large. The divergence angle of the light guided while being reflected is two-dimensionally converted to be smaller and is irradiated onto the irradiation target. Therefore, it is possible to two-dimensionally secure a depth of focus that is longer than the conventional one.

In the optical transmission device according to the fourth aspect of the present invention, the refractive index of the medium provided on the optical axis side of the third reflecting surface is provided between the first reflecting surface and the second reflecting surface. Since it is larger than the refractive index of the medium, for example, the second and third reflections are made so that the angle of the reflected light transmitted through the first and second reflecting surfaces with respect to the optical axis becomes gradually smaller along the optical axis direction. When the surface is tilted, the number of reflections in the third reflecting surface having a slight tilt angle with respect to the optical axis of the emitted laser light is reduced, and expansion of the outgoing angle from the spread angle conversion light guide path is suppressed. Can ensure a longer depth of focus.

Since the optical transmission device according to the invention of claim 5 is provided with an air layer between the first and second transparent members,
The laser light is totally reflected on each of the reflection surfaces of the first and second transparent members and is transmitted through the divergence angle conversion light guide path. Therefore, the light energy loss of the laser light at the time of reflection can be eliminated.

In the optical transmission device according to the sixth aspect of the present invention, since the cooling means causes the cooling fluid to flow in the air layer between the first and second transparent members, the thermal expansion of the first and second transparent members is suppressed. As a result, the divergence angle conversion light guide path can have a long life.

In the optical transmission device according to the seventh aspect of the present invention, the magnifying and imaging lens magnifies and images the exit surface of the optical fiber on the entrance surface of the divergence angle conversion light guide. Therefore, the diameter of the divergence angle conversion light guide can be made larger than that of the optical fiber, and the divergence angle conversion light guide can be designed without being limited by the size of the optical fiber.

In the optical transmission device of the present invention, the incident angle control means controls the angle formed by the optical axis of the laser beam focused by the incident optical system and the optical axis of the optical fiber to be 0 degree or more. In order to do so, for example, the incident surface of the optical fiber is moved, so that the intensity distribution of the light emitted from the divergence angle conversion light guide path can be changed, and as a result, the intensity distribution of the light emitted to the irradiation target can be changed.

In the optical transmission device according to the ninth aspect of the present invention, the image forming lens forms an image of the laser light transmitted through the opening of the perforated concave mirror near the entrance end face of the optical fiber. Thus, regardless of the oscillation state of the laser oscillator, the laser light can be stably incident on the optical fiber for a long time without damaging the optical fiber. Further, since the perforated concave mirror is used, the cooling mechanism for the opening can be omitted.

The optical transmission device according to the invention of claim 10 is
A light energy amount measuring means measures the light energy of the reflected light from the peripheral portion of the opening of the perforated concave mirror. Thereby, the state change of the laser oscillator can be known.

The optical transmission device according to the invention of claim 11 is
The optical means of the incident optical system changes the divergence angle of a part of the laser light output from the laser oscillator. As a result, damage to the optical fiber can be suppressed, and a larger amount of light energy can be guided to the optical fiber.

An optical transmission device according to a twelfth aspect of the invention is
The optical means converts the divergence angle of the central portion in the cross section of the laser beam into a smaller value.

An optical transmission device according to the invention of claim 13 is
The optical filter of the incident optical system changes the phase distribution of the laser light output from the laser oscillator. As a result, damage to the optical fiber can be suppressed, and a larger amount of light energy can be guided to the optical fiber.

The optical transmission device according to the invention of claim 14 is
The phase of the central portion of the laser light incident on the optical filter in the cross-sectional direction is delayed or advanced as compared with the phase of the light of other portions by the optical filter.

[0038]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. 1 is a block diagram showing an optical transmission apparatus according to an embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 23 designate the same or corresponding parts, and the description thereof will be omitted. Further, in the figure, 8 is a divergence angle conversion light guide path for converting the divergence angle of a part of the light emitted from the optical fiber 3 to a smaller one, and 9 is laser light emitted from the divergence angle conversion light guide path 8. The irradiation optical system is composed of the divergence angle conversion light guide 8 and the second lens 7.

Next, the operation will be described. The emitted laser light (laser light) 2 output from the laser oscillator 1 is focused by the first lens (incident optical system, imaging lens) 4 and is incident on the optical fiber 3 from this one end surface. Optical fiber 3
The laser light guided by is emitted from the other end of the optical fiber 3. The laser light emitted from the optical fiber 3 enters the divergence angle conversion light guide 8 where the divergence angle of a part of the laser light is converted to a smaller one. A part of the laser light 9 emitted from the divergence angle conversion light guide path 8 has a smaller divergence angle than the laser light emitted from the optical fiber 3, and is irradiated onto the irradiation target 6 by the second lens 7.

The laser light 2 emitted from the laser oscillator 1 is
Although it is coherent light with high coherence, the coherence is remarkably lowered by being reflected multiple times in the multimode optical fiber 3 for high energy transmission.
The laser light emitted from is incoherent light.

FIG. 2 is an explanatory view showing the laser light emitted from the optical fiber 3 as a model. In the figure, the same reference numerals as those in FIG. 1 denote the same parts, and 5 denotes the light from the optical fiber 3. Emitted laser light (laser light), 10
Is a modeled point light source, 11 is an emission end face of the optical fiber 3, and 12 is an optical axis of the emitted laser light 5 from the optical fiber 3. The exit end face 11 of the optical fiber 3 has an optical axis 12
With respect to 0 ° to the maximum divergence angle ± θ ₀ (where θ ₀ is substantially equal to the focusing angle of the incident laser light and does not exceed the NA of the optical fiber 3), the point light source that emits the emitted laser light 5 It can be regarded as 10 gathered faces.
The exit end face 11 of the optical fiber 3 and the divergence angle conversion light guide 8
By matching the entrance end face of the laser light 5, the laser light 5 emitted from each point light source 10 enters the divergence angle conversion light guide path 8.

Next, the behavior of light in the divergence angle conversion light guide 8 will be described in detail with reference to FIG. FIG. 3 is a configuration diagram showing the divergence angle conversion light guide 8 used in the optical transmission apparatus according to this embodiment. In the figure, the same reference numerals as those in FIG. 2 denote the same parts, and 8a denotes the light. first reflecting member cylindrical or plate-shaped having a first reflecting surface 80a parallel to axis 12, 8b is a second reflecting surface 80b and the rear side thereof inclined at an inclination angle theta _t with respect to the optical axis 12 A second reflection member having a cylindrical shape (strictly, a truncated cone shape) or a plate shape having a third reflection surface 80c which is a surface, and 9a denotes a first reflection member 8a.
Is an example of laser light incident between the second reflection member 8b and the second reflection member 8b, 9b is an example of laser light incident into the second reflection member 8b, and 13 is an emission end face of the divergence angle conversion light guide path 8.
In this embodiment, the first and second reflecting members 8a, 8a
b is made of metal, and the first and second reflecting members 8a and 8b
The medium in the space and in the second reflecting member 8b is air. When the first and second reflecting members 8a and 8b are plate-shaped, each of the first and second reflecting members 8a and 8b is composed of two reflecting plates.

As shown in FIG. 3, the divergence angle conversion light guide 8 having a length L has a reflecting member 8 having a first reflecting surface 80a parallel to the optical axis 12 of the laser light 5 emitted from the optical fiber 3.
and a, second and third reflecting surfaces 80b inclined at an inclination angle theta _t with respect to the optical axis 12, 80c is configured by a reflection member 8b having the light incident on the divergence angle converting light guides 8 Reflecting surfaces 80a, 8 of the first and second reflecting members 8a, 8b
The light is guided while being reflected by 0b and 80c and emitted from the emission end face 13.

The laser beam 9a incident at an angle θ ₁ between the first and second reflecting members 8a and 8b (however, the maximum incident angle θ _1max depends on the refractive index of the medium, and in the case of air, the optical fiber 3 is used). Spread angle θ of the emitted laser beam 5 of
(Equal to 0), the angle of the laser beam 9a with respect to the optical axis 12 is further increased according to the tilt angle θ _t each time it is reflected by the second reflecting surface 80 b tilted at the tilt angle θ _t of the second reflecting member 8 b. Converted to be smaller. On the other hand, the laser beam 9b incident on the second reflecting member 8b at the angle θ ₂ (similarly, the maximum incident angle θ _2max = θ ₀ ) is the third reflecting light of the second reflecting member 8b inclined at the inclination angle θ _t . The angle of the laser beam 9b with respect to the optical axis 12 is converted so as to be larger each time it is reflected by the reflection surface 80c. At this time, the emission angles θ _1out and θ _2out of the laser beams 9a and 9b from the divergence angle conversion light guide path 8 are
The number of reflections by the reflecting member 8b is m ₁ and m ₂ , respectively, and is represented by the following formula from the law of reflection.

Θ _1out = θ ₁ -2 × m ₁ × θ _t (1) θ _2out = θ ₂ + 2 × m ₂ × θ _t (2) Therefore, when the number of reflections m ₁ and m ₂ is 1 or more , Θ _1out <
θ ₁ and θ _2out > θ ₂ . For the purposes of this invention, the larger m _{1 and the} smaller m _{2, the} greater the effect.

By the way, the number of reflections is expressed as a function of the following variables. m ₁ (θ ₁ , d ₁ , L, θ _t ) m ₂ (θ ₂ , d ₂ , L, θ _t ) (3) However, the first reflecting member on the emission end face 13 of the divergence angle conversion light guide path 8 The distance between 8a and the second reflecting member 8b is d ₁ , and the inner diameter of the second reflecting member 8b is d ₂ .
For example, θ ₁ = θ ₂ = 0.2 degrees, d ₁ = 0.08 mm, d
₂ = 0.24 mm, L = 2 mm, θ _t = 0.5 degree,
θ _1out = 0.14 degrees <θ ₁ , θ _2out = 0.25 degrees> θ ₂
Becomes

In this way, the emitted laser light 9 whose divergence angle is converted by the divergence angle conversion light guide path 8 is irradiated by the second lens 7 so as to form an image on the emission end face 13 of the divergence angle conversion light guide path 8. The body 6 is irradiated.

FIG. 4 is an explanatory view showing a state of laser light in the vicinity of the image plane by the optical transmission apparatus according to this embodiment. In the figure, 6a is an image plane and 14 is a beam emitted from a conventional optical transmission apparatus. An example of the laser light, 15 is an example of the laser light emitted from between the first reflection member 8a and the second reflection member 8b, and 16 is an example of the light emitted from the inside of the second reflection member 8b. As shown in FIG. 4, the laser light 15 whose divergence angle is converted to a smaller one by the divergence angle conversion light guide 8 spreads at an angle smaller than that of the conventional laser light 14. Further, since the light 16 whose divergence angle has been converted to a greater extent spreads from the center of the image, a distance that is A times the outer diameter (radius r in FIG. 4) of the imaged spot is defined as the depth of focus.
It is possible to secure a longer depth of focus than before.

FIG. 5 is a graph showing the result of calculation of the relationship between the depth of focus and the imaging magnification in the optical transmission apparatus according to this embodiment and the conventional optical transmission apparatus. When compared at the same depth of focus, the imaging magnification can be made smaller than in the prior art. Therefore, when the optical fiber 3 having the same core diameter is used, a smaller imaging spot can be obtained, and the imaging having the same diameter as the conventional one. In the case of a spot, it becomes possible to use an optical fiber 3 having a larger core diameter.

In this embodiment, as described above,
The first and second reflecting members 8a and 8b have a cylindrical shape or a plate shape. In the case of a plate shape, the above-mentioned action is limited to one-dimensional, and in the case of a cylindrical shape, the above-mentioned action is It goes without saying that it is two-dimensionally affected.

In this embodiment, the first and second reflecting members 8a and 8b are made of metal, but the material is not limited to this as long as it is a substance that reflects light.

Further, the number of reflecting members forming the divergence angle converting light guide 8 and the kind of medium between the reflecting members are not limited to those described above.

Embodiment 2 FIG. FIG. 6 is a cross-sectional view showing the configuration of the divergence angle conversion light guide 8 in the optical transmission device according to another embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 3 denote the same parts. A duplicate description will be omitted.
Further, in the figure, 17 is the first and second reflecting members 8
It is a medium having a refractive index higher than that of the medium between a and 8b.

As shown in FIG. 6, the divergence angle conversion light guide 8 having the length L has a first reflecting member having a first reflecting surface 80a parallel to the optical axis 12 of the laser light 5 emitted from the optical fiber 3. 8a and the second tilted at the tilt angle θ _t2 with respect to the optical axis 12.
And a second reflecting member 8b having third reflecting surfaces 80b and 80c, the laser light incident on the divergence angle converting light guide path 8 is guided while being reflected by the respective reflecting surfaces 80a, 80b and 80c. To be done. In this embodiment, as in the first embodiment, the first and second reflecting members 8a and 8b are made of metal, the medium between the first and second reflecting members 8a and 8b is air, and the second The medium in the reflecting member 8b has a refractive index larger than that of air.

Next, the operation will be described. In the following, only the characteristic operation of the divergence angle conversion light guide 8 according to this embodiment will be described, and the other portions will be described in the first embodiment.
Since it is similar to the above, duplicate description will be omitted. Assuming that the refractive index of the medium between the first and second reflecting members 8a and 8b is n ₁ and the refractive index of the medium inside the second reflecting member 8b is n ₂ , the first and second reflecting members 8a and 8b. Laser light 9a incident between
The maximum incident angle θ ₁ (indicated by the broken line) and the second reflecting member 8b
The maximum incident angle θ _{2 of} the laser beam 9b (indicated by a solid line) that has entered the inside is the maximum spread angle θ ₀ of the laser beam 5 emitted from the optical fiber 3 and the refractive index n _{0 of} air according to Snell's law. Is expressed by the following equation.

Θ ₁ = Sin ⁻¹ (n ₀ / n ₁ × Sin θ ₀ ) (4) θ ₂ = Sin ⁻¹ (n ₀ / n ₂ × Sin θ ₀ ) (5) Equations (4) and (5) ), The refractive index n ₁ of the medium between the first and second reflecting members 8a and 8b and the refractive index n ₂ of the medium in the second reflecting member 8b are larger than the refractive index n _{0 of} air. In this case, the maximum incident angles θ ₁ and θ ₂ are smaller than θ ₀ . The number of reflections m on each surface is represented by a function of the incident angle, and the number of reflections m becomes small when the light is incident at a small angle. In this embodiment, since the relationship of the refractive index n ₂ of the medium in the second reflecting member 8b> the refractive index n ₀ of the air is established, the number of reflections m ₂ becomes a value smaller than that when the medium is air. , Θ _2out expressed by the equation (2) also becomes small.

FIG. 7 is a graph showing the result of calculation of the relationship between the depth of focus and the imaging magnification in the optical transmission device according to this embodiment. In the case of the same imaging magnification, the optical transmission device according to this embodiment can secure a longer depth of focus than that of the first embodiment. That is, comparing at the same depth of focus,
Since the imaging magnification can be made smaller than in the conventional case and the first embodiment,
When the optical fiber 3 having the same core diameter is used, a smaller image forming spot can be obtained, and in the case of the image forming spot having the same diameter as the conventional and the first embodiment, the optical fiber 3 having the larger core diameter is used. It becomes possible.

In this embodiment also, the first and second
The reflecting members 8a and 8b are cylindrical or plate-shaped, and in the case of a plate, the above-mentioned action is limited to one-dimensional, and in the case of a cylindrical shape, the above-mentioned action is two-dimensional. It goes without saying that it will be done.

In this embodiment, the first and second reflecting members 8a and 8b are made of metal, but the material is not limited to this as long as it is a substance that reflects light.

Further, the medium between the first and second reflecting members 8a and 8b forming the divergence angle converting light guide 8 is air, but the medium is smaller than the refractive index of the medium in the second reflecting member 8b. However, it is not limited to this.

Example 3. FIG. 8 is a sectional view showing the structure of the divergence angle conversion light guide 8 of the optical transmission device according to another embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 3 denote the same parts. A duplicate description will be omitted. Also,
In the figure, 19 is the first and second reflecting surfaces 80a, 80.
a cylindrical or plate-shaped first transparent member having b, 20
Is a cylindrical or plate-shaped second transparent member having the third reflection surface 80c, 21a is an example of laser light incident on the first transparent member 19, and 21b is incident on the second transparent member 20. It is an example of a laser beam. The first transparent member 19
Is a plate shape, the first transparent member 19 is composed of two plate members. In addition, as shown in FIG.
The second transparent members 19 and 20 are not in close contact with each other, and a medium having a refractive index smaller than the refractive index of the first and second transparent members 19 and 20 is provided in the gap between the transparent members 19 and 20. An air layer, for example of air, is provided.

Next, the operation will be described. In the following, only the characteristic operation of the divergence angle conversion light guide 8 according to this embodiment will be described, and the other portions will be described in the first embodiment.
Since it is similar to the above, duplicate description will be omitted. Optical fiber 3
The emitted laser light 5 emitted from the laser light enters the first and second transparent members 19 and 20 of the divergence angle conversion light guide 8 having the length L. The laser light incident on the first transparent member 19 having the first reflection surface 80a parallel to the optical axis 12 and the second reflection surface 80b inclined at the inclination angle θt3 with respect to the optical axis 12 is the laser light 21a. Like the first reflective surface 80a and the second reflective surface 8
The light is guided through the first transparent member 19 while being totally reflected alternately with 0b. On the other hand, the laser light incident on the second transparent member 20 having the third reflecting surface 80c is totally reflected a plurality of times within the third reflecting surface 80c like the laser light 21b, and then the second
The light is guided through the transparent member 20.

As described above, according to this embodiment, the laser light 5 emitted from the optical fiber 3 is converted into the divergence angle conversion light guide path 8.
Since the light is guided while being totally reflected by the first and second transparent members 19 and 20, it is possible to eliminate the light energy loss of the laser light at the time of reflection.

Incidentally, also in this embodiment, the first and second
The transparent members 19 and 20 are cylindrical or plate-shaped, and in the case of a plate, the above-mentioned action is limited to one-dimensional, and in the case of a cylindrical shape, the above-mentioned action is two-dimensional. It goes without saying that it will be done.

Further, the first and second transparent members 19 and 20
May be made of different materials or the same material.

Example 4. FIG. 9 is a sectional view showing a structure of a cooling device for a spread angle converting light guide 8 of an optical transmission device according to another embodiment of the present invention. In the figure, the same reference numerals as those in FIG. Only the parts are shown and duplicate explanations are omitted. Further, in the figure, 22a and 22b are transparent members for windows, 23 is a gas or liquid cooling fluid for cooling the first and second transparent members 19 and 20, and 24 is a transparent member for windows 22a and 22b. A holding member having an opening through which the cooling fluid 23 flows in and out.

Next, the operation will be described. In the following, only the characteristic operation of the cooling device for the divergence angle conversion light guide path 8 according to this embodiment will be described, and the other parts are the same as those in the above-described first and third embodiments, and thus the duplicate description will be omitted. Spreading angle conversion light guide 8 and window transparent member 22
The members a and 22b are held by a holding member 24. The cooling fluid 23 flows in through the opening provided in the holding member 24 from the incident surface side of the divergence angle conversion light guide path 8 and flows through the gap between the first and second transparent members 19 and 20. The first and second transparent members 19 and 20 are cooled, and flow out to the outside from the opening of the divergence angle conversion light guide 8 on the emission surface side. As a result, the cooling fluid 23 is supplied to the first and second transparent members 19,
It is possible to suppress thermal expansion due to optical energy loss of the laser light in 20.

The refraction index of the cooling fluid 23 is the first and the second.
Needless to say, it is smaller than the refractive index of the transparent members 19 and 20. As a result, the laser light incident on the divergence angle conversion light guide path 8 is guided while being totally reflected by the first, second and third reflection surfaces 80a, 80b, 80c of the first and second transparent members 19, 20. To be done.

Example 5. FIG. 10 is a configuration diagram showing a divergence angle conversion light guide 8 of an optical transmission device according to another embodiment of the present invention. In the figure, the same reference numerals as those in FIGS. 1 and 3 denote the same parts. Therefore, duplicate description will be omitted. Further, in the figure, 25 is a magnifying image forming lens, and 26 is a magnifying image forming surface of the exit end face 11 of the optical fiber 3.

Next, the operation will be described. In the following, only the characteristic operation of the divergence angle conversion light guide 8 according to this embodiment will be described, and the other portions will be described in the first embodiment.
Since it is similar to the above, duplicate description will be omitted. Optical fiber 3
The outgoing laser light 5 output from the outgoing end face 11 of is expanded and imaged by the magnifying and imaging lens 25 and is incident on the divergence angle conversion light guide 8. The divergence angle conversion light guide path 8 is installed so that the entrance surface thereof coincides with the enlarged image forming surface 26 of the exit end surface 11 of the optical fiber 3.

As described above, according to this embodiment, the laser beam 5 emitted from the optical fiber 3 is magnified and imaged by the magnifying and imaging lens 25 so that the divergence angle conversion light guide 8 has a larger diameter than the optical fiber 3. Can be

Example 6. FIG. 11 is a block diagram showing an optical transmission apparatus according to another embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same parts, and a duplicate description will be omitted. Further, in the figure, reference numeral 27 is an incident angle control mechanism (incident angle control means) for controlling the incident angle of the laser light on the optical fiber 3.

Next, the operation will be described. In the following, only the characteristic operation of the divergence angle conversion light guide 8 according to this embodiment will be described, and the other portions will be described in the first embodiment.
Since it is similar to the above, duplicate description will be omitted. As shown in FIG. 11, the emitted laser light 2 output from the laser oscillator 1 is focused by the first lens 4 and enters the optical fiber 3 from this one end surface. At this time, the angle between the optical axis of the optical fiber 3 and the optical axis of the incident laser beam becomes θ by the incident angle control mechanism 27 provided at the entrance of the optical fiber 3, and the center position of the entrance of the optical fiber 3 is set. It is controlled to be incident.

12 (a) and 12 (b) respectively show the laser light emitted from the optical fiber 3 and the laser light emitted from the divergence angle conversion light guide 8 when the incident angle with respect to the optical fiber 3 is changed from 0 degree. It is a graph which shows intensity distribution. As shown in FIG. 12A, when the incident angle is gradually changed from 0 degree to the optical fiber 3 and the light is incident, the intensity distribution of the laser light emitted from the optical fiber 3 changes from a substantially Gaussian shape to a substantially rectangular shape. Can be changed to a substantially annular shape. According to this, the intensity distribution of the laser light incident on the divergence angle conversion light guide path 8 can be changed,
As shown in FIG. 12B, the intensity distribution of the laser light emitted from the divergence angle conversion light guide path 8 changes, and the intensity distribution of the laser light applied to the irradiation target 6 can be changed. .

Example 7. FIG. 13 is a perspective view showing the structure of an incident optical system of an optical transmission device according to another embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same parts, and a duplicate description will be omitted. Omit it. In the figure, 28 is a long-focal-length concave concave mirror, 29 is an opening of the concave concave mirror 28, and 30 is a light energy measuring device (light energy measuring means).

Next, the operation will be described. It is generally observed that the oscillation state of the laser oscillator 1 is not constant over a long period of time, and the emission direction and the spread angle of the emitted laser light 2 change. A change in the emission angle changes the focused spot position of the first lens 4, and a change in the spread angle changes the focused spot diameter. In either case, in the positional relationship between the fixed first lens 4 for focusing light and the optical fiber 3, the optical fiber 3 is changed by the change in the coupling ratio of the optical energy, and the optical energy applied to the portion other than the core of the optical fiber 3. Will be damaged.

As shown in FIG. 13, the first lens 4 guides only the laser light passing through the opening 29 to the optical fiber 3. The size of the opening 29 is set so that the light energy loss of the laser light 2 emitted from the laser oscillator 1 is as small as possible. The first lens 4 has an opening 29.
The focal length and the positional relationship are selected so as to form an image on the end face of the core of the optical fiber 3. For example, when the intensity distribution of the emitted laser beam 2 is a Gaussian distribution and the 1 / e ² diameter is φ5 mm, if the diameter of the opening 29 is φ10 mm, about 99% of the optical energy of the emitted laser beam 2 can be transmitted. . When the distance a from the perforated concave mirror 28 to the first lens 4 and the distance b from the first lens 4 to the core end surface of the optical fiber 3 are 500 mm and 50 mm, respectively, the laser light emitted to the optical fiber 3 with a core diameter of φ1 mm is emitted. About 99% of the light energy of 2 can be guided. From this, by forming the image of the opening 29 on the end surface of the core of the optical fiber 3, the emitted laser light 2 can be stably reflected on the optical fiber 3 for a long time without damaging the optical fiber 3 regardless of the oscillation state of the laser oscillator 1. You can see that you can guide light.

Further, a concave mirror 28 with a long focal length and having a hole is provided.
Is installed so as to be slightly inclined with respect to the optical axis, and the light energy of the emitted laser light 2 collected by the concave mirror with a hole 28 is incident on the light energy measuring device 30 for measuring the light energy. It Since changes in the emission direction and spread angle of the emitted laser beam 2 from the laser oscillator 1 can be observed as changes in the amount of light energy measured by the optical energy amount measuring device 30, it is necessary to know the state change of the laser oscillator 1. You can

Further, since the surface of the perforated concave mirror 28 other than the opening 29 is a mirror surface, the opening 29
It is also possible to omit the cooling mechanism.

Example 8. FIG. 14 is a cross-sectional view showing the structure of an incident optical system of an optical transmission device according to another embodiment of the present invention. In the figure, the same reference numerals as those in FIG. Omit it. Further, in the figure, 31 is a parallel transparent substrate that reduces the spread angle of a part of the laser beam 2 emitted from the laser oscillator 1, 32 is a refractive index distribution forming portion (optical means) of the parallel transparent substrate 31, and 33 is parallel transparent. Laser light emitted from the refractive index distribution forming portion 32 of the substrate 31, 34 is the refractive index distribution forming portion 32 of the parallel transparent substrate 31.
It is the laser light emitted from other parts. Further, FIG. 15 is a plan view of the parallel transparent substrate 31.

Next, the operation will be described. The laser light 2 emitted from the laser oscillator 1 has a slight divergence angle. The parallel transparent substrate 31 is for reducing only the divergence angle near the optical axis of the emitted laser light 2, and FIG.
As shown in FIG. 7, a part of the flat transparent substrate 31 is provided with a refractive index distribution forming portion 32 by an ion exchange method or the like.
Emitted laser light 33 emitted from the refractive index distribution forming unit 32
Has a divergence angle smaller than that of the emitted laser light 34 that did not pass through the refractive index distribution forming portion 32 due to the refractive power of the refractive index distribution forming portion 32. The emitted laser beams 33 and 34 are focused by the first lens 4, but have different spread angles and thus are focused at different focusing positions. The condensing position A of the emitted laser light 33 having a smaller divergence angle is closer to the first lens 4 than the condensing position B of the emitted laser light 34.

FIG. 16 is a graph showing a comparison of the light energy concentration distribution at the condensing position by the conventional incident optical system and the light energy concentration distribution at the position B by the incident optical system of this embodiment. In, the horizontal axis represents the distance in the radial direction from the center of the focused spot, and the vertical axis represents the ratio of the light energy contained in the diameter with 100% as the upper limit. As can be seen from FIG. 16, according to this embodiment, the local concentration of light energy is improved, and the local power density can be reduced. Therefore, by disposing the incident end face of the optical fiber 3 near the position B, damage to the optical fiber 3 can be suppressed, and a larger amount of light energy can be guided to the optical fiber 3.

Example 9. FIG. 17 is a cross-sectional view showing the structure of an incident optical system of an optical transmission device according to another embodiment of the present invention. In the figure, the same reference numerals as those in FIG. Omit it. Further, in the figure, reference numeral 35 is a cylindrical lens (optical means) for reducing the spread angle of a part of the laser light 2 emitted from the laser oscillator 1, and 36 is the laser light emitted from the cylindrical lens 35.

Next, the operation will be described. The laser light 2 emitted from the laser oscillator 1 has a slight divergence angle. The emitted laser light 36 emitted from the cylindrical lens 35 having a refractive power in the x direction in FIG. 17 is more in the x direction than the other emitted laser light 2 that has not passed through the cylindrical lens 35 due to the refractive power of the cylindrical lens 35. , Will have a small spread angle. The emitted laser light 36 and the other emitted laser light 2 are emitted from the first lens 4
However, since the divergence angle is different, the light is condensed at a different condensing position. The condensing position A of the emitted laser light 36 having a smaller divergence angle is closer to the first lens 4 than the condensing position B of the other emitted laser light 2.

Therefore, according to this embodiment, the local concentration of the light energy is improved as in the case of the above-mentioned embodiment 8, and by disposing the incident end face of the optical fiber 3 near the position B, the optical fiber 3 Since it is possible to suppress damage to the optical fiber 3, a larger amount of light energy can be guided to the optical fiber 3.

Example 10. FIG. 18 is a cross-sectional view showing the structure of an incident optical system of an optical transmission device according to another embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 14 denote the same parts, and a duplicate description will be omitted. Omit it. In the figure, 37 is an optical filter, 38 is an optical filter 3.
A light-transmissive substrate constituting 7, a first light-transmissive layer 39, and a second light-transmissive layer 40.

FIG. 19 (a) is a plan view schematically showing the structure of the optical filter 37, and FIG. 19 (b) is shown in FIG.
It is sectional drawing of the optical filter 37 along the AA 'line of (a). The optical filter 37 is formed by laminating two kinds of first and second light transmitting layers 39 and 40 having different refractive indexes at a central portion and a peripheral portion on one surface of a light transmitting substrate 38 in a uniform thickness. ing. The light transmissive layers 39 and 40 may each have a low refractive index or a high refractive index. The diameter d2 of the optical filter 37 is large enough to transmit the light energy of the emitted laser light 2.

Next, the operation will be described. The laser light 2 emitted from the laser oscillator 1 passes through the first light transmitting layer 39 and the second light transmitting layer 40 of the optical filter 37 installed immediately before the first lens 4 and has a spatial phase distribution. The light is condensed by the first lens 4 in the changed state.

FIG. 20A shows the optical filter 37
Phase distribution diagram of emitted laser beam 2 before irradiation, FIG.
Is the refractive index (n_c Is the second)
Refractive index of transparent layer 40 (n_d Optical fiber
Phase distribution of the emitted laser beam 2 after passing through the filter 37
In the figure, the horizontal axis represents the radial distance from the center of the laser beam,
The vertical axis represents the phase. 20 (a) and 20
As apparent from (b), the light enters the optical filter 37.
The phase is approximately straight in the radial direction of the beam.
It is a spherical surface with a curvature close to a line, but the optical filter 3
After passing through 7, the thickness of the first and second translucent layers 39 and 40 is changed.
Δ and the wavelength of the laser light is λ, (n_c -N _d ) × Δ ×
Only λ of the emitted laser light 2 transmitted through the first transparent layer 39
The phase of the emitted laser light 2 having the phase transmitted through the second transparent layer 40.
It will be later than the phase.

FIG. 21 is a graph showing an example of the intensity distribution on the light-collecting surface by the first lens 4, where the horizontal axis represents the radial distance of the focused spot and the vertical axis represents the intensity. Further, FIG. 22 shows the concentration distribution of the optical energy of the emitted laser light 2 at the converging position by the incident optical system of this example and the conventional incident optical system, and the horizontal axis represents the radial direction from the center of the converging spot. Distance, vertical axis is the ratio of the light energy contained in the diameter is 1
The upper limit is 00%. As is clear from these figures, the intensity distribution of the focused spot by the first lens 4 is greatly changed by this embodiment, the local concentration of light energy is improved, and the local power density is improved. Can be lowered.

Therefore, according to this embodiment, similarly to Embodiments 8 and 9, the local concentration of light energy is improved, and the incident end face of the optical fiber 3 is installed in the vicinity of the light collecting surface. By doing so, damage to the optical fiber 3 can be suppressed, and a larger amount of light energy can be guided to the optical fiber 3.

Needless to say, since the optical filter 37 does not block light, the optical filter 37
The light energy of the laser light before and after passing through is the same.

[0093]

As described above, according to the first aspect of the invention, the irradiation of irradiating the irradiated object with the emitted laser light by converting the spread angle of at least a part of the laser light emitted from the optical fiber to a smaller value. Since it is configured to include the optical system, there is an effect that it is possible to secure a longer depth of focus than before. Therefore, a smaller spot can be obtained on the object to be irradiated, and high energy can be made incident by the fiber having a larger core diameter, so that the object to be irradiated can be irradiated with a larger energy density.

According to the second aspect of the present invention, the first reflecting surface parallel to the optical axis of the laser light emitted from the optical fiber and the optical axis side of the first reflecting surface are provided, and the first reflecting surface is provided with respect to the optical axis. Since it is configured to include the divergence angle conversion light guide having at least the second reflecting surface inclined and the third reflecting surface which is the back surface thereof, it is possible to secure a longer depth of focus than the conventional one. is there.

According to the invention of claim 3, the cylindrical first reflecting member having the first reflecting surface and the cylindrical first reflecting member having the second and third reflecting surfaces inclined with respect to the optical axis. Since it is configured to include two reflecting members, there is an effect that a longer depth of focus can be secured two-dimensionally than in the conventional case.

According to the invention of claim 4, the medium provided on the optical axis side of the third reflecting surface has a refractive index of between the first reflecting surface and the second reflecting surface. Since it is configured to be larger than the refractive index of, the expansion of the emission angle from the divergence angle conversion light guide path can be suppressed, and a longer focal depth can be secured.

According to the fifth aspect of the invention, the first transparent member having the first and second reflecting surfaces and the second transparent member having the third reflecting surface are provided. Further, since the air layer is provided between the second transparent member and the second transparent member, there is an effect that the light energy loss of the laser light at the time of reflection can be eliminated.

According to the sixth aspect of the present invention, the cooling means for flowing the cooling fluid to the air layer is provided.
Also, there is an effect that the thermal expansion of the second transparent member is suppressed and the life of the divergence angle conversion light guide path can be extended.

According to the seventh aspect of the present invention, there is provided a magnifying imaging lens for magnifying and imaging the exit surface of the optical fiber, and the entrance surface of the divergence angle conversion light guide path is installed on the magnifying imaging surface of the magnifying imaging lens. With this configuration, the diameter of the divergence angle conversion light guide path can be made larger than that of the optical fiber, and the divergence angle conversion light guide path can be designed without being limited by the size of the optical fiber.

According to the invention of claim 8, there is provided an incident angle control means for controlling the angle formed by the optical axis of the laser beam condensed by the incident optical system and the optical axis of the optical fiber to be 0 degree or more. With this configuration, there is an effect that the intensity distribution of the laser light with which the irradiation target is irradiated can be changed.

According to the invention of claim 9, a long-focal-length concave mirror having an opening at the center, which is installed slightly inclined with respect to the optical axis of the laser beam, and an opening of the concave-hole perforated mirror. Since it is configured to have an imaging lens that forms an image near the entrance end face of the optical fiber, the laser light is stably incident on the optical fiber for a long time without damaging the optical fiber regardless of the oscillation state of the laser oscillator. There is an effect that can be done. Further, since the perforated concave mirror is used, there is an effect that the cooling mechanism for the opening can be omitted.

According to the tenth aspect of the present invention, since the optical energy amount measuring means for measuring the optical energy of the reflected light from the peripheral portion of the opening of the perforated concave mirror is provided, it is possible to change the state of the laser oscillator. There is an effect that you can know.

According to the eleventh aspect of the present invention, since the optical means for changing the divergence angle of a part of the laser light output from the light source such as the laser oscillator is provided, damage to the optical fiber can be suppressed. Therefore, there is an effect that a larger amount of light energy can be guided to the optical fiber.

According to the twelfth aspect of the invention, since the means for converting the divergence angle of the central portion in the cross section of the laser light to a smaller one is constituted, damage to the optical fiber can be suppressed, so that larger light is emitted. This has the effect of guiding the amount of energy to the optical fiber.

According to the thirteenth aspect of the present invention, since the optical filter for changing the phase distribution of the laser light output from the light source such as the laser oscillator is provided, damage to the optical fiber can be suppressed. There is an effect that a larger amount of light energy can be guided to the optical fiber.

According to the fourteenth aspect of the present invention, the optical filter is configured so as to generate a phase difference between the central portion of the incident laser light in the cross-sectional direction and the other portion. Since the damage to the optical fiber can be suppressed, there is an effect that a larger amount of light energy can be guided to the optical fiber.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an optical transmission device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a model of laser light emitted from an optical fiber.

FIG. 3 is a cross-sectional view showing a configuration of a divergence angle conversion light guide path of the optical transmission device according to the embodiment.

FIG. 4 is an explanatory diagram showing a state of laser light in the vicinity of an image plane in the optical transmission device according to the above-mentioned embodiment.

FIG. 5 is a graph showing the relationship between the imaging magnification and the depth of focus in the optical transmission device according to the above embodiment.

FIG. 6 is a cross-sectional view showing a configuration of a divergence angle conversion light guide path of an optical transmission device according to another embodiment of the present invention.

FIG. 7 is a graph showing a relationship between an imaging magnification and a depth of focus in the optical transmission device according to the above embodiment.

FIG. 8 is a sectional view showing a configuration of a divergence angle conversion light guide path of an optical transmission device according to another embodiment of the present invention.

FIG. 9 is a sectional view showing a structure of a cooling device for a divergence angle conversion light guide of an optical transmission device according to another embodiment of the present invention.

FIG. 10 is a sectional view showing a configuration of a spread angle conversion light guide of an optical transmission device according to another embodiment of the present invention.

FIG. 11 is a configuration diagram showing an optical transmission device according to another embodiment of the present invention.

FIG. 12 is a graph showing the intensity distributions of the laser light emitted from the optical fiber and the laser light emitted from the divergence angle conversion light guide when the incident angle with respect to the optical fiber of the optical transmission device of the above embodiment is changed from 0 degrees. Is.

FIG. 13 is a sectional view showing a configuration of an incident optical system of an optical transmission device according to another embodiment of the present invention.

FIG. 14 is a sectional view showing a configuration of an incident optical system of an optical transmission device according to another embodiment of the present invention.

FIG. 15 is a plan view of a parallel transparent substrate of the incident optical system of the above example.

FIG. 16 is a graph showing a concentration distribution of light energy of laser light by the parallel transparent substrate of the above example.

FIG. 17 is a sectional view showing a configuration of an incident optical system of an optical transmission device according to another embodiment of the present invention.

FIG. 18 is a sectional view showing a configuration of an incident optical system of an optical transmission device according to another embodiment of the present invention.

19A and 19B are a plan view and a cross-sectional view of an optical filter of the incident optical system of the above example.

FIG. 20 is a graph showing a phase distribution of laser light transmitted through the optical filter of the above-mentioned embodiment.

FIG. 21 is a graph showing the intensity distribution of a focused spot of laser light that has passed through the optical filter of the above example.

FIG. 22 is a graph showing a concentration distribution of light energy of laser light by the optical filter of the above-mentioned embodiment.

FIG. 23 is a configuration diagram showing a conventional optical transmission device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 laser oscillator, 2 and 5 emitted laser light (laser light), 3 optical fiber, 4 1st lens (incident optical system, imaging lens), 6 irradiation object, 7 2nd lens (irradiation optical system), 8 Spread angle conversion light guide (irradiation optical system), 8a first reflecting member, 8b second reflecting member,
19 first transparent member, 20 second transparent member, 23
Cooling fluid, 25 Magnification imaging lens, 27 Incident angle control mechanism (incident angle control means), 28 Perforated concave mirror, 29 Opening part, 30 Light energy amount measuring device (light energy amount measuring means), 32 Refractive index distribution Forming part (optical means), 35 cylindrical lens (optical means),
37 optical filter, 80a first reflecting surface, 80b
Second reflective surface, 80c Third reflective surface.

Claims (14)

[Claims] 1. An incident optical system for making a laser beam outputted from a laser oscillator incident on an optical fiber, and a spread angle of at least a part of a laser beam emitted from the optical fiber are converted to be smaller, and the emitted laser beam is irradiated. An optical transmission device comprising an irradiation optical system for irradiating the body. 2. The irradiation optical system is provided on a first reflecting surface parallel to the optical axis of the laser light emitted from the optical fiber, and on the optical axis side of the first reflecting surface,
The optical transmission device according to claim 1, further comprising: a divergence angle conversion light guide path having a second reflection surface that is inclined with respect to the optical axis and a third reflection surface that is a back surface thereof. 3. The divergence angle conversion light guide path has a cylindrical first reflecting member having the first reflecting surface, and second and third reflecting surfaces inclined with respect to the optical axis. The optical transmission device according to claim 2, further comprising a cylindrical second reflecting member. 4. The refractive index of the medium provided on the optical axis side of the third reflecting surface is the refractive index of the medium provided between the first reflecting surface and the second reflecting surface. The optical transmission device according to claim 2 or 3, wherein the optical transmission device is larger than the above. 5. The divergence angle conversion light guide path includes a first transparent member having the first and second reflecting surfaces, and a second transparent member having the third reflecting surface. Cage,
The optical transmission device according to claim 2, further comprising an air layer between the first and second transparent members. 6. The optical transmission device according to claim 5, further comprising a cooling unit that causes a cooling fluid to flow in the air layer. 7. A magnifying imaging lens for magnifying and imaging the exit surface of the optical fiber is provided, and an entrance surface of the divergence angle conversion light guide path is provided on the magnifying imaging surface of the magnifying imaging lens. The optical transmission device according to any one of claims 2 to 6. 8. An incident angle control means for controlling the angle formed by the optical axis of the laser beam focused by the incident optical system and the optical axis of the optical fiber to be 0 degrees or more. The optical transmission device according to any one of claims 2 to 6. 9. An optical transmission device comprising an incident optical system for making laser light output from a light source such as a laser oscillator incident on an optical fiber, wherein the incident optical system is slightly inclined with respect to the optical axis of the laser light. A long-focal-length concave concave mirror having an opening in the center, and an imaging lens for forming an image of the opening of the concave concave mirror near the entrance end surface of the optical fiber. A characteristic optical transmission device. 10. The optical transmission device according to claim 9, further comprising optical energy amount measuring means for measuring optical energy of reflected light from a peripheral portion of the opening of the perforated concave mirror. 11. An optical transmission device comprising an incident optical system for making laser light outputted from a light source such as a laser oscillator incident on an optical fiber, wherein the incident optical system is a part of the laser light outputted from the light source. An optical transmission device comprising optical means for changing a divergence angle. 12. The optical transmission device according to claim 11, wherein the optical means is a means for converting the divergence angle of the central portion of the cross section of the laser light to a smaller value. 13. An optical transmission device comprising an incident optical system for making laser light outputted from a laser oscillator incident on an optical fiber, wherein the incident optical system changes a phase distribution of the laser light outputted from the laser oscillator. An optical transmission device comprising an optical filter. 14. The optical filter is an optical filter configured to generate a phase difference between a central portion in a cross-sectional direction of the incident laser light and other portions. 13. The optical transmission device according to 13.