Ultraviolet light irradiation device, and ultraviolet light irradiation method

Abstract

To provide an ultraviolet light irradiation device capable of efficiently irradiating ultraviolet light to a local area, and an ultraviolet light irradiation method.SOLUTION: An ultraviolet light irradiation device includes a laser light source that emits first light with a primary emission wavelength in the range longer than 400 nm, an optical system that reduces the divergence angle of the first light emitted from the laser light source, and a nonlinear optical crystal element that receives the first light transmitted through the optical system and converts it into second light with a primary emission wavelength in the range of 200 nm to 235 nm, and a first housing part with at least the optical system and the nonlinear optical crystal element arranged inside, and forming a closed space that isolates the optical system and the nonlinear optical crystal element relative to an external space, the first housing portion has a light emission section that transmits the second light and emits it to the outside at a portion of its side.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present invention relates to an ultraviolet light irradiation device and an ultraviolet light irradiation method.

Background Art

[0002] Conventionally, a technique of inactivating bacteria or viruses in space using ultraviolet light emitted by an excimer lamp or the like has been studied (see, for example, Patent Document 1 below). In this specification, "inactivation" is used as a concept including killing at least a part of bacteria or viruses or reducing their infectivity.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The targets for which inactivation of bacteria or viruses is required are not limited to space but cover a wide range. For example, there are cases where it is desired to inactivate bacteria or viruses in local areas such as the skin surface or oral cavity of the human body. However, since the device disclosed in Patent Document 1 has a structure in which ultraviolet light is irradiated from a light irradiation window provided in the housing, ultraviolet light is irradiated over a relatively wide area. Therefore, there is room for improvement in inactivating bacteria and viruses in local areas.

[0005] Specifically, in order to irradiate ultraviolet light toward a local area, it is assumed that the light irradiation window of the ultraviolet light irradiation device is brought close to the irradiation target area. However, application of a high-frequency voltage is required to light the excimer lamp. Since a step-up transformer or the like that generates a high-frequency voltage has a certain volume, the above ultraviolet light irradiation device tends to be large-sized, and it is not easy to bring the irradiation window of the ultraviolet light irradiation device close to the irradiation target area.

[0006] On the other hand, a method of configuring the apparatus to be relatively small by using an LED that emits ultraviolet light instead of an excimer lamp can be considered. However, at present, LEDs that emit ultraviolet light have a problem in that the luminous efficiency with respect to the input power is low, and it is not practical to use an LED as an ultraviolet light source.

[0007] By the way, wavelength conversion technology using a non-linear optical crystal element that converts the energy of incident light to obtain light of a shorter wavelength by non-linear optical phenomena is known. Specifically, by making the laser light emitted from a laser light source incident on the non-linear optical crystal element, light having half the wavelength of the laser light (also referred to as "second harmonic") or light having one-third the wavelength (also referred to as "third harmonic") can be obtained.

[0008] It is easy to design the non-linear optical crystal element to be small. Therefore, according to the configuration of obtaining ultraviolet light by the laser light source and the non-linear optical crystal element, it becomes easy to bring the non-linear optical crystal element closer to the irradiation target region, and ultraviolet light can be preferably irradiated to a local region.

[0009] However, the inventors of the present invention considered generating ultraviolet light by a laser light source and a non-linear optical crystal element and irradiating the local region with the ultraviolet light, and faced the problem that the non-linear optical crystal element is easily deteriorated and ultraviolet light cannot be efficiently irradiated.

[0010] An object of the present invention is to provide an ultraviolet light irradiation device and an ultraviolet light irradiation method capable of efficiently performing ultraviolet light irradiation on a local region in view of the above circumstances.

Means for Solving the Problems

[0011] The ultraviolet light irradiation device according to the present invention includes a laser light source that emits first light whose main wavelength belongs to a range longer than 400 nm, an optical system that reduces the divergence angle of the first light emitted from the laser light source, A non-linear optical crystal element into which the first light transmitted through the optical system is incident, and which converts the first light into second light having a main wavelength belonging to the range of 200 nm to 235 nm and emits the converted light. At least the optical system and the non-linear optical crystal element are disposed inside, and a first housing portion is provided that forms a closed space that isolates the optical system and the non-linear optical crystal element from the external space. The first housing portion is characterized by having a light emitting portion that transmits the second light through a part of a side surface and emits the light to the outside.

[0012] In this specification, the "main wavelength" refers to a wavelength range that exhibits a light intensity of 40% or more with respect to the highest light intensity (peak intensity) in an emission spectrum obtained by decomposing the light intensity by wavelength. Typically, the main wavelength includes the wavelength (peak wavelength) that exhibits the peak intensity.

[0013] A laser light source is a light source capable of emitting coherent light. As the laser light source, for example, a semiconductor laser (laser diode), a solid-state laser such as a YAG laser, a gas laser such as a CO2 laser, or a gas laser such as an organic dye laser can be employed. From the viewpoint of facilitating miniaturization of the apparatus, a semiconductor laser is preferable.

[0014] Ultraviolet light (corresponding to the "second light") is obtained by wavelength-converting the laser light (corresponding to the "first light") emitted from the laser light source using a non-linear optical crystal element. Since the illuminance of ultraviolet light attenuates as the traveling distance increases, it is preferable to bring the irradiation target region and the non-linear optical crystal element as close as possible in order to efficiently irradiate the irradiation target region with ultraviolet light. According to the above configuration, as long as the laser light is incident, the position of the non-linear optical crystal element with respect to the irradiation target region can be easily designed. Therefore, even if the irradiation target region is a local region, it becomes easy to bring the non-linear optical crystal element close to the region.

[0015] The inventors of the present invention considered the reasons for the phenomenon that the non-linear optical crystal element deteriorates when ultraviolet light is generated by a laser light source and a non-linear optical crystal element and the local area is irradiated with the ultraviolet light as follows.

[0016] Since many non-linear optical crystal elements have the property of deteriorating and reducing the conversion efficiency when they come into contact with moisture in the air, when irradiating ultraviolet light on a local area, as a result of the non-linear optical crystal element coming into contact with the atmosphere of the local area, it is considered that the non-linear optical crystal element deteriorates and the efficiency of generating ultraviolet light decreases. In addition, when the irradiation target area and the non-linear optical crystal element are brought closer, it is considered that the non-linear optical crystal element is more likely to be affected by the atmosphere of the irradiation target area and is more likely to deteriorate. In particular, as the local area, a high-humidity environment such as inside the oral cavity or abdominal cavity of the human body is also assumed, and in such a high-humidity environment, it is expected that the influence of the deterioration of the non-linear optical crystal element will become more prominent.

[0017] On the other hand, according to the above configuration, the non-linear optical crystal element is arranged in the closed space formed by the first accommodating portion. Thereby, the deterioration of the non-linear optical crystal element due to contact with the atmosphere of the irradiation target area is suppressed. By suppressing the deterioration of the non-linear optical crystal element, the output of the ultraviolet light irradiation device is less likely to decrease, and the irradiation of ultraviolet light can be efficiently performed.

[0018] Examples of the local area include the skin surface of an animal (including the human body). As another example, areas inside the body of an animal such as the oral cavity, nasal cavity, and abdominal cavity can be mentioned. Furthermore, ultraviolet light may be irradiated on a narrow area that is difficult for a person's hand to reach, such as a drain such as a sink.

[0019] In the above ultraviolet light irradiation device, The non-linear optical crystal element may be arranged in a space hermetically sealed from the external space.

[0020] For example, since body fluids exist in regions within the body of an animal such as the oral cavity, such regions tend to be in a high-humidity environment. According to the above configuration, even in such a high-humidity environment, deterioration of the nonlinear optical crystal element can be more strongly suppressed, and ultraviolet light can be efficiently irradiated. Specific examples of the configuration in which the nonlinear optical crystal element is disposed in a hermetically sealed space will be described later.

[0021] The ultraviolet light irradiation device may have a protective film that covers the surface of the nonlinear optical crystal element and transmits the first light and the second light.

[0022] According to the above configuration, the nonlinear optical crystal element is disposed in the closed space formed by the protective film. That is, the nonlinear optical crystal element is covered not only by the first housing portion but also by the protective film, so that contact between the nonlinear optical crystal element and the external atmosphere is more strongly suppressed.

[0023] Further, the ultraviolet light irradiation device includes a second housing portion that is disposed in the closed space formed by the first housing portion and has a light transmission portion that transmits the second light at a partial location on a side surface, the second housing portion has the optical system, the nonlinear optical crystal element, and the laser light source disposed therein, and isolates the optical system, the nonlinear optical crystal element, and the laser light source from the space outside the second housing portion in the closed space, the light transmission portion may be disposed between the nonlinear optical crystal element and the light emitting portion with respect to the traveling direction of the second light.

[0024] According to the above configuration, the nonlinear optical crystal element is doubly covered by the first housing portion and the second housing portion. Thereby, contact between the nonlinear optical crystal element and the external atmosphere is more strongly suppressed, which is preferable.

[0025] The ultraviolet light irradiation device includes a laser unit equipped with the laser light source, An optical fiber that is connected to the laser unit and guides the first light emitted by the laser light source into the first housing portion. A connection portion provided at a partial location on the side surface of the first housing portion to which the optical fiber is connected. It may include a sealing portion that seals the connection portion.

[0026] According to the above configuration, the laser unit equipped with the laser light source and the first housing portion having the light emitting portion are configured separately. As a result, it becomes easier to configure the first housing portion in a small size. As a result, it becomes easy to bring the first housing portion closer to the local area, and ultraviolet light irradiation can be performed more efficiently.

[0027] Note that it is assumed that when the first housing portion and the optical fiber are connected, it becomes easier for the external atmosphere to enter the first housing portion from the connection portion. On the other hand, according to the above configuration, the connection between the optical fiber and the connection portion of the first housing portion is sealed by the sealing portion. As a result, it becomes difficult for external air or the like to enter the first housing portion, and deterioration of the nonlinear optical crystal element due to contact with the air is suppressed.

[0028] In the above ultraviolet light irradiation device, Regarding the path through which at least one of the first light and the second light travels, the distance from the nonlinear optical crystal element to the light emitting portion may be shorter than the distance from the laser light source to the nonlinear optical crystal element.

[0029] When comparing the second light, which is ultraviolet light, with the first light, which is laser light having a longer wavelength than the ultraviolet light, the second light is more likely to attenuate. For this reason, it is preferable that the path through which the first light travels is made longer than the path through which the second light travels between the laser light source and the light emitting portion.

[0030] Also, from the viewpoint of arranging the nonlinear optical crystal element at a position as close as possible to the light emitting portion and obtaining the second light, which is ultraviolet light, near the light emitting portion, the separation distance between the nonlinear optical crystal element and the light emitting portion may be within 10 cm with respect to the direction in which the light emitting portion emits the second light.

[0031] The light emitting unit may be made of a material that exhibits diffusibility with respect to the second light.

[0032] As described above, since the nonlinear optical crystal element converts laser light to obtain the second light which is ultraviolet light, the second light also becomes highly directional light like the first light. Although the second light is suitable for irradiation of a local region, it is also assumed that there may be a case where it is desired to irradiate the second light over a wider range within the local region. According to the above configuration, since the second light is diffused in the light emitting unit, the irradiation region of the second light can be expanded.

[0033] The ultraviolet light irradiation device may include a diffusion member made of a material that exhibits diffusibility with respect to the second light and configured to be attachable to the light emitting unit.

[0034] More preferably, the irradiation range of the ultraviolet light can be changed according to the irradiation target region. According to the above configuration, it is possible to easily switch whether or not to diffuse the second light in the light emitting unit. Specific examples will be described later.

[0035] The ultraviolet light irradiation device includes a holding member that holds the nonlinear optical crystal element in a state where the nonlinear optical crystal element is in communication with the inner wall of the first housing portion, and the holding member may be made of one or more materials selected from the group consisting of copper, silver, aluminum, and brass.

[0036] The nonlinear optical crystal element does not convert all of the incident laser light into ultraviolet light, and a part of the incident laser light is converted into heat. That is, the nonlinear optical crystal element generates heat when irradiated with laser light. From the viewpoint of suppressing deterioration of the nonlinear optical crystal element due to the influence of the heat, the holding member in contact with the nonlinear optical crystal element is preferably made of a material having a high thermal conductivity such as copper, silver, aluminum, and brass.

[0037] The ultraviolet light irradiation device When viewing the light emitting part from the direction opposite to the direction in which the light emitting part emits the second light, the maximum width of the light emitting part may be 20 mm or less.

[0038] According to the above configuration, it becomes easy to insert the light emitting part into a narrow part such as inside the oral cavity or the abdominal cavity. Thereby, irradiation with ultraviolet light on a local area can be performed more efficiently.

[0039] The light emitting part may be inserted into the body of an animal and configured to be able to irradiate the second light into the body.

[0040] The ultraviolet light irradiation method according to the present invention a step (a) of making a first light belonging to a wavelength range longer than 400 nm incident on a nonlinear optical crystal element disposed in a closed space to obtain a second light belonging to a wavelength range of 200 nm to 235 nm; and a step (b) of irradiating an irradiation target region with the second light emitted from the closed space, characterized by comprising the steps.

[0041] According to the above method, since the nonlinear optical crystal element is disposed in a closed space, deterioration of the nonlinear optical crystal element is suppressed by the atmosphere around the irradiation target region. Thereby, the ultraviolet light obtained from the nonlinear optical crystal element can be efficiently irradiated onto the irradiation target region.

[0042] The step (b) may be a step of irradiating the irradiation target region in the body of an animal with the second light.

[0043] Further, the step (a) may be a step of making the first light incident on the nonlinear optical crystal element disposed in a hermetically sealed space.

[0044] By disposing the nonlinear optical crystal element in a hermetically sealed space, it is possible to more strongly suppress the deterioration of the nonlinear optical crystal element while performing ultraviolet light irradiation.

[0045] The step (a) may include a step of generating the second light in the vicinity of the irradiation target region.

[0046] In order to generate ultraviolet light, which is the second light, in the vicinity of the irradiation target region, it is preferable to bring a non-linear optical crystal element close to the irradiation target region. However, when the non-linear optical crystal element approaches the irradiation target region, it is considered that the non-linear optical crystal element is likely to deteriorate due to the atmosphere around the irradiation target region. On the other hand, in the above method, since the non-linear optical crystal element is arranged in the closed space, even if the non-linear optical crystal element approaches the irradiation target region, the deterioration of the non-linear optical crystal element is suppressed.

Advantages of the Invention

[0047] According to the present invention, there are provided an ultraviolet light irradiation device and an ultraviolet light irradiation method capable of efficiently performing irradiation of ultraviolet light on a local region.

Brief Description of the Drawings

[0048]

Figure 1A

Figure 1B

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8A

Figure 8B

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0049] Embodiments of the ultraviolet light irradiation device and the ultraviolet light irradiation method according to the present invention will be described with reference to the drawings as appropriate. Note that the following drawings are schematically illustrated, and the dimensional ratios on the drawings do not necessarily match the actual dimensional ratios. Also, the dimensional ratios do not necessarily match between the drawings.

[0050] [First Embodiment] FIGS. 1A and 1B are cross-sectional views schematically showing the structure of the ultraviolet light irradiation device, and some elements are shown in a block diagram. In the following figures, an X - Y - Z coordinate system composed of the X direction, Y direction, and Z direction orthogonal to each other is appropriately referred to.

[0051] Also, in the following description, when distinguishing between positive and negative directions when expressing a direction, it is described with positive and negative signs such as “+X direction” and “-X direction”. When expressing a direction without distinguishing between positive and negative directions, it is simply described as “X direction”. That is, in this specification, when simply described as “X direction”, both “+X direction” and “-X direction” are included. The same applies to the Y direction and Z direction.

[0052] The ultraviolet light irradiation device 1 irradiates the irradiation target region W1 with ultraviolet light U1 to inactivate bacteria and viruses that may exist in the irradiation target region W1. Hereinafter, after explaining the configuration of the ultraviolet light irradiation device 1, the ultraviolet light irradiation method executable by the ultraviolet light irradiation device 1 will be described.

[0053] As shown in FIG. 1A, the ultraviolet light irradiation device 1 includes a laser light source 2, an optical system 3, a non-linear optical crystal element 4 (hereinafter, for convenience, referred to as "NLO element 4"), a power supply unit 5, and a housing unit 6.

[0054] The housing unit 6 is composed of a cylindrical body portion 7 and a light emitting portion 8. In FIG. 1B, for the purpose of easy understanding, a state in which the cylindrical body portion 7 and the light emitting portion 8 are disassembled is shown. As shown in FIG. 1B, the cylindrical body portion 7 has an opening 10 in the end face on the +X side. The light emitting portion 8 covers the opening 10 and transmits the ultraviolet light U1 emitted by the NLO element 4 described later and emits it to the outside. The housing unit 6 forms a closed space S1 by the cylindrical body portion 7 and the light emitting portion 8. The laser light source 2, the optical system 3, the NLO element 4, and the power supply unit 5 are arranged in the closed space S1 and are isolated from the external space.

[0055] The light emitting portion 8 is made of a material that transmits the ultraviolet light U1. As a more detailed example, it is made of a fluorine-based resin such as PTFE (polytetrafluoroethylene) or a glass material such as quartz glass. When irradiating the ultraviolet light U1 to inactivate bacteria and viruses at a predetermined location in the body of an animal using the ultraviolet light irradiation device 1, the irradiation target region W1 in FIG. 1A is a region in the body of the animal. In such a case, from the viewpoint of suppressing the physical impact on the body, it is preferable to configure the light emitting portion 8 with a flexible member such as a fluorine-based resin.

[0056] In addition, as examples of other flexible members, fluorine-based resins such as PCTFE (polychlorotrifluoroethylene), ETFE (ethylene tetrafluoroethylene), PFA (perfluoroalkoxy alkane), PVDF (polyvinylidene fluoride), or FEP (perfluoroethylene propene copolymer), PP (polypropylene), PE (polyethylene), PVA (polyvinyl alcohol), PVC (polyvinyl chloride), COC (cyclic olefin copolymer), silicone resin, etc. can also be used. These materials have the property that when the thickness is reduced, permeability to ultraviolet light can be obtained. As an example, the thickness is set to 0.01 mm to 1 mm.

[0057] The cylindrical body portion 7 is preferably made of a material having resistance to ultraviolet light U1, and is made of, for example, a metal material such as aluminum, stainless steel, or brass. The metal material typically exhibits a water vapor transmission rate of 2 or less, and is a suitable material for forming a space in which the closed space S1 is hermetically sealed from the outside, as will be described later. Also, from the viewpoint of low water vapor transmission rate, the cylindrical body portion 7 may be made of a resin material such as PP or PE.

[0058] Further, the cylindrical body portion 7 may be composed of, for example, a member made of the above metal material and a member made of the above resin material. In this case, at the joint portion between the members, it is preferable to use a fluororesin such as PTFE, or a film such as a biaxially stretched PP film or a silica-deposited film.

[0059] The accommodating portion 6 corresponds to the "first accommodating portion".

[0060] In the present embodiment, the laser light source 2 is a semiconductor laser that emits laser light L1 whose main wavelength belongs to a range longer than 400 nm. The laser light L1 corresponds to the "first light". More preferably, the main wavelength of the laser light L1 is 400 nm to 460 nm.

[0061] The semiconductor laser can be operated by a relatively small voltage of, for example, about 1 V to 5 V. Therefore, if a semiconductor laser is adopted as the laser light source 2, it becomes easier to configure the cylindrical body portion 7 to be smaller, which is preferable. Also, for example, the power supply portion 5 can be configured with a battery.

[0062] The NLO element 4 converts a part of the energy of the incident laser light L1 by non-linear optical phenomena to generate ultraviolet light U1. As the NLO element 4, for example, a BBO (BaB2O4) crystal, a CLBO (CsLiB6O 10 ) crystal, or an AlN crystal having a polarization inversion structure can be used. In the present embodiment, the ultraviolet light U1 as the second harmonic of the laser light L1 is obtained by the NLO element 4. The ultraviolet light U1 corresponds to the "second light".

[0063] From the perspective of suppressing the influence of irradiation on the human body, the ultraviolet light U1 preferably belongs to the range of 200 nm to 235 nm in terms of the main wavelength. Further, the main wavelength of the ultraviolet light U1 more preferably belongs to the range of 200 nm to 230 nm. Note that it is optional that the ultraviolet light U1 is the second harmonic of the laser light L1. For example, by performing wavelength conversion with a plurality of NLO elements 4, higher-order harmonics higher than the second harmonic may be generated to obtain the ultraviolet light U1. The configuration of the NLO element 4 can be appropriately adjusted according to the wavelength of the laser light L1.

[0064] The power supply unit 5 is a means for supplying power to the laser light source 2, and may be a battery or a circuit unit for generating a current necessary for the emission of the laser light source 2 from a commercial power supply.

[0065] The optical system 3 guides the laser light L1 emitted from the laser light source 2 to the NLO element 4. As an example, the optical system 3 includes a collimator lens 3a that makes the laser light L1 emitted from the laser light source 2 into parallel light, and a condenser lens 3b that condenses the laser light L1 transmitted through the collimator lens 3a onto the NLO element 4.

[0066] Although the laser light L1 emitted from the laser light source 2 is light with higher directivity than, for example, the light emitted by an LED, in order to efficiently convert the laser light L1 into the ultraviolet light U1 with the NLO element 4, it is necessary to make the range in which the laser light L1 enters the NLO element 4 as small as possible. In view of this, the optical system 3 is configured to guide the laser light L1 to the NLO element 4 while reducing the divergence angle of the laser light L1.

[0067] Since all of the NLO elements 4 made of the materials listed above have the property of being hygroscopic, they are liable to deteriorate when they come into contact with the external atmosphere. In particular, when the irradiation target area W1 is an area where a high-humidity environment such as inside the oral cavity is assumed, the contact between this atmosphere and the NLO element 4 may cause the deterioration of the NLO element 4 to be accelerated. On the other hand, in the ultraviolet irradiation device 1 of the present embodiment, since the NLO element 4 is disposed in the closed space S1, the atmosphere outside the ultraviolet irradiation device 1 is less likely to come into contact with the NLO element 4, and the progress of the deterioration of the NLO element 4 is suppressed.

[0068] In particular, when irradiating the irradiation target area W1 in a high-humidity environment such as inside the oral cavity or the abdominal cavity with the ultraviolet light U1, from the viewpoint of suppressing the deterioration of the NLO element 4, it is preferable that the closed space S1 be a space hermetically sealed from the outside. As an example, while the cylindrical body portion 7 is made of the material having a low water vapor permeability described above, by covering the opening 10 of the cylindrical body portion 7 with the light emitting portion 8, the housing portion 6 forms the closed space S1 and the closed space S1 can be a space hermetically sealed from the external space.

[0069] Also, in this case, from the same viewpoint as that of the cylindrical body portion 7, the light emitting portion 8 is preferably made of a material having a low water vapor permeability, such as a fluororesin or a glass material such as quartz glass. In particular, PTFE is a suitable material in terms of having a low water vapor permeability and being easy to process.

[0070] Note that a method for verifying whether or not the closed space S1 is hermetically sealed from the external space will be described later.

[0071] FIG. 2 is a drawing of the ultraviolet light irradiation device 1 according to FIG. 1A as viewed from the light emitting unit 8 side. In FIG. 2, for convenience of illustration, the light emitting unit 8 is shown as being transparent. As shown in FIGS. 1A and 2, the NLO element 4 is supported by a holding member 9 that connects the inner wall 7a of the cylindrical body 7 and the NLO element 4. For example, the NLO element 4 is fixed to the holding member 9 by an adhesive (9a, 9b). More specifically, the adhesive 9a adheres the -Z side surface of the NLO element 4 and the -Y side surface of the holding member 9, and the adhesive 9b adheres the -Y side surface of the NLO element 4 and the -Z side surface of the holding member 9. As the adhesive (9a, 9b), for example, Site Top (registered trademark) or the like can be used.

[0072] The NLO element 4 generates heat when the laser beam L1 is incident thereon. In order to suppress deterioration of the NLO element 4 due to the heat, the holding member 9 is preferably made of a material having a high thermal conductivity. Examples of such materials include metal materials such as copper, silver, aluminum, or brass.

[0073] Also, as shown in FIGS. 1A and 2, the NLO element 4 has a rectangular parallelepiped shape, and typically emits ultraviolet light U1 in its longitudinal direction. As shown in FIG. 2, the NLO element 4 contacts the holding member 9 on the +Z side surface and the +Y side surface.

[0074] It is assumed that the NLO element 4 and the holding member 9 thermally expand due to the heat generated by the NLO element 4. Here, when the thermal expansion coefficient of the holding member 9 is larger than that of the NLO element 4, stress due to the thermal expansion of the holding member 9 is applied to the NLO element 4. If the NLO element 4 contacts the holding member 9 on both side surfaces related to the Z direction and both side surfaces related to the Y direction, the stress on the NLO element 4 increases. In view of this, as shown in FIG. 2, it is preferable that two mutually intersecting side surfaces composed of the +Z side surface and the +Y side surface are in contact with the holding member 9, and the -Z side surface and the -Y side surface, which are different from the side surfaces, are open surfaces that do not contact the holding member 9.

[0075] In FIG. 2, the adhesive 9a is shown as contacting a partial region of the -Z side surface of the NLO element 4, but the adhesive 9a may be arranged to cover the -Z side surface of the NLO element 4. The same applies to the adhesive 9b and the -Y side surface of the NLO element 4. Also, the adhesive 9a and the adhesive 9b may be in contact and integrated with each other.

[0076] The holding member 9 may support the NLO element 4 and may also support the collimator lens 3a and the condenser lens 3b. Also, a plurality of holding members 9 may be arranged, and each holding member 9 may support each of the NLO element 4, the collimator lens 3a, and the condenser lens 3b.

[0077] In FIG. 1A, the traveling modes of the laser beam L1 and the ultraviolet light U1 are schematically illustrated. As shown in FIG. 1A, the laser light source 2 is driven by the supply of electric power from the power supply unit 5, and the laser beam L1 is incident on the NLO element 4 through the optical system 3. The NLO element 4 emits ultraviolet light U1 due to the incidence of the laser beam L1. Thus, the step of making the laser beam L1 incident on the NLO element 4 disposed in the closed space S1 to obtain the ultraviolet light U1 corresponds to step (a).

[0078] The ultraviolet light U1 emitted from the NLO element 4 is irradiated onto the irradiation target region W1 after passing through the light emission unit 8. Thus, the step of irradiating the ultraviolet light U1 onto the irradiation target region W1 corresponds to step (b).

[0079] Since the ultraviolet light U1 is light with a shorter wavelength than the laser beam L1, the ultraviolet light U1 is more likely to attenuate compared to the laser beam L1. For this reason, as shown in FIG. 1A, the distance D2 from the NLO element 4 to the light emission unit 8 is preferably made shorter than the distance D1 from the laser light source 2 to the NLO element 4 in the optical axis direction of the laser beam L1 and the ultraviolet light U1. In other words, with respect to the path along which at least one of the laser beam L1 and the ultraviolet light U1 travels, the NLO element 4 is preferably disposed closer to the light emission unit 8 side than the intermediate position of the path.

[0080] Also, from the viewpoint of making it difficult for the ultraviolet light U1 to attenuate before entering the light emitting portion 8, the NLO element 4 is preferably disposed near the light emitting portion 8. Specifically, the distance D2 is preferably within 10 cm, more preferably within 5 cm, and particularly preferably within 1 cm in the direction in which the NLO element 4 emits the ultraviolet light U1.

[0081] Furthermore, from the viewpoint of making it difficult for the ultraviolet light U1 emitted from the light emitting portion 8 to attenuate before reaching the irradiation target region W1, it is preferable to bring the light emitting portion 8 as close as possible to the irradiation target region W1. For example, when the irradiation target region W1 is inside an animal such as in the oral cavity, the ultraviolet light U1 is irradiated in a state where the light emitting portion 8 is inserted into the oral cavity or in a state where the light emitting portion 8 is brought close to the vicinity of the entrance of the oral cavity. Thus, it is preferable to generate the ultraviolet light U1 in the vicinity of the irradiation target region W1. Note that the "vicinity of the irradiation target region W1" may mean a range within 5 cm from the irradiation target region W1. Preferably, the distance is within 3 cm, and more preferably, the distance is within 1 cm.

[0082] When the light emitting portion 8 is brought close to the irradiation target region W1 with the NLO element 4 disposed near the light emitting portion 8, it is considered that the NLO element 4 is likely to be affected by the atmosphere of the irradiation target region W1. However, as described above, since the NLO element 4 is disposed in the closed space S1, deterioration of the NLO element 4 due to the influence of the atmosphere is suppressed.

[0083] Also, in order to irradiate a wider range in the irradiation target region W1 while bringing the light emitting portion 8 closer to the irradiation target region W1, the light emitting portion 8 may be configured to exhibit diffusibility with respect to the ultraviolet light U1. In this case, it is preferable to configure the light emitting portion 8 with a fluororesin such as PTFE. In FIG. 1A, the state in which the ultraviolet light U1 is transmitted while being diffused by the light emitting portion 8 is schematically illustrated.

[0084] Furthermore, from the viewpoint of facilitating the insertion of the light emitting unit 8 into a narrow area such as the oral cavity, when viewing the light emitting unit 8 from the direction opposite to the direction in which the light emitting unit 8 emits the ultraviolet light U1, the maximum width R1 of the light emitting unit 8 is preferably 20 mm or less, and more preferably 10 mm or less (see FIG. 2).

[0085] Next, a method for verifying whether the space in which the NLO element 4 is disposed in the ultraviolet light irradiation device 1 is hermetically sealed from the external space will be described. Hereinafter, the method will be described by dividing it into Steps 1 to 5.

[0086] (Step 1) First, prepare the ultraviolet light irradiation device 1 to be verified and an ultraviolet light irradiation device 1 of the same product. Hereinafter, for the sake of distinction between the two, the former will be referred to as the "target sample" and the latter as the "standard sample".

[0087] (Step 2) Measure the illuminance of the ultraviolet light U1 emitted by each of the target sample and the standard sample. The illuminance of the ultraviolet light U1 is measured with an illuminometer disposed at a predetermined distance from the light emitting unit 8.

[0088] Hereinafter, for the sake of convenience, the illuminance of the target sample measured in Step 2 will be referred to as "initial illuminance A1", and the illuminance of the standard sample will be referred to as "initial illuminance B1".

[0089] (Step 3) Next, place the target sample in a dew condensation environment, that is, an environment adjusted to a relative humidity of about 100%. Also, place the standard sample in an environment adjusted to a relative humidity of 20% or less. Then, leave it in the above state for 30 days. For adjusting the relative humidity, for example, a thermo-hygrostat can be used.

[0090] (Step 4) Then, after taking out the target sample and the standard sample, the illuminance of the ultraviolet light U1 emitted by each of the target sample and the standard sample is measured under the same conditions as the illuminance measurement in Step 2. For convenience, the illuminance of the target sample measured in Step 4 is referred to as "Illuminance A2", and the illuminance of the standard sample is referred to as "Illuminance B2".

[0091] (Step 5) Finally, the reduction ratio A3 of Illuminance A2 with respect to the initial illuminance A1 and the reduction ratio B3 of Illuminance B2 with respect to the initial illuminance B1 are respectively derived.

[0092] In Step 3, the target sample is arranged in an environment with a higher humidity than the standard sample, and it is considered that the deterioration of the NLO element 4 becomes more prominent. However, if the NLO element 4 is arranged in a hermetically sealed space, it is considered that the reduction ratio A3 and the reduction ratio B3 will be equal. That is, when the reduction ratio A3 is less than or equal to the reduction ratio B3, it can be said that the NLO element 4 is hermetically sealed in the ultraviolet light irradiation device 1.

[0093] [Second Embodiment] Next, regarding the second embodiment of the ultraviolet light irradiation device 1, the parts different from the first embodiment will be mainly described. FIG. 3 is a cross-sectional view schematically showing a configuration example of the ultraviolet light irradiation device 1 according to the second embodiment following FIG. 1A.

[0094] As shown in FIG. 3, the ultraviolet light irradiation device 1 has a housing portion 16 arranged in a closed space S1 (not shown in FIG. 3, refer to FIG. 1A) formed by the housing portion 6. The housing portion 16 is composed of a cylindrical portion 17 having an opening (not shown) on the end face on the +X side, and a light transmissive portion 18 that covers the opening and transmits ultraviolet light U1. The housing portion 16 corresponds to the "second housing portion".

[0095] The housing portion 16 forms a closed space S2 by the cylindrical portion 17 and the light transmissive portion 18. The laser light source 2, the optical system 3, the NLO element 4, and the power supply portion 5 are arranged in the closed space S2 and are isolated from the space S11 outside the housing portion 16 in the closed space S1 formed by the housing portion 6.

[0096] The closed space S2 is a space that is more strongly isolated from the external space than the space S11 by being covered by the housing portion 16 in addition to the housing portion 6. That is, the closed space S2 is a space with higher airtightness than the space S11 with respect to the external space. By arranging the NLO element 4 in the closed space S2, it is more strongly suppressed that the NLO element 4 is deteriorated by the atmosphere outside the housing portion 6.

[0097] As shown in FIG. 3, the light transmission portion 18 is arranged between the NLO element 4 and the light emission portion 8 with respect to the traveling direction of the ultraviolet light U1. The ultraviolet light U1 is emitted to the outside from the light emission portion 8 through the light transmission portion 18. In the present embodiment, from the viewpoint of suppressing the diffusion when the ultraviolet light U1 passes through the light transmission portion 18, the light transmission portion 18 is preferably made of a glass material such as quartz glass.

[0098] Regarding the point that the NLO element 4 is held on the inner wall 17a of the cylindrical body portion 17 via the holding member 9, by reading "cylindrical body portion 7" as "cylindrical body portion 17" and "inner wall 7a" as "inner wall 17a", the same discussion as that described with reference to FIG. 2 is possible.

[0099] Regarding the material that can constitute the cylindrical body portion 17, the same discussion as that of the cylindrical body portion 7 is possible.

[0100] According to the second embodiment, since the NLO element 4 is arranged in a space that is more airtightly sealed with respect to the external space, the deterioration of the NLO element 4 due to moisture absorption or the like is more strongly suppressed. This embodiment is suitable for irradiating the irradiation target region W1 in a high humidity environment such as in the oral cavity or abdominal cavity with the ultraviolet light U1.

[0101] [Third Embodiment] In this embodiment, similar to the second embodiment, the NLO element 4 is arranged in a space that is airtightly sealed with respect to the external space. FIG. 4 is a cross-sectional view schematically showing a configuration example of the ultraviolet light irradiation device 1 according to the third embodiment following FIG. 1A. Further, FIG. 5 is a drawing of the ultraviolet light irradiation device according to FIG. 4 as viewed from the light emission portion 8 side.

[0102] As shown in FIGS. 4 and 5, by disposing the protective film 12 on the surface of the NLO element 4, the NLO element 4 can be disposed within the space formed by the protective film 12. The space is a space that is more strongly isolated from the external space than the closed space S1 by being covered with the protective film 12 and the housing portion 6. That is, the space formed by the protective film 12 is a space with higher airtightness than the closed space S1 with respect to the external space. Thereby, the deterioration of the NLO element 4 due to the atmosphere outside the housing portion 6 is more strongly suppressed.

[0103] The protective film 12 is assumed to be transparent to both the laser light L1 and the ultraviolet light U1. Examples of the material constituting the protective film 12 include MgF2, HfO2, or Ta2O5.

[0104] [Fourth Embodiment] Next, a fourth embodiment of the ultraviolet light irradiation device according to the present invention will be described focusing on the parts different from the first embodiment. FIG. 6 is a cross-sectional view schematically showing a configuration example of the ultraviolet light irradiation device 1 according to the fourth embodiment following FIG. 1A. In FIG. 6, the illustration of the optical fiber 30 and the sealing portion 32, which will be described later, is simplified, and the details of the configuration will be described in detail with reference to FIG. 7.

[0105] As shown in FIG. 6, this embodiment is different from the first embodiment in that it includes a laser unit 20 equipped with a laser light source 2 and a power supply unit 5, and an optical fiber 30 that guides the laser light L1 from the laser unit 20 to the housing portion 6.

[0106] The laser unit 20 includes a collimator lens 21 and a condenser lens 22 inside. The collimator lens 21 and the condenser lens 22 guide the laser light L1 emitted from the laser light source 2 to the optical fiber 30.

[0107] Also, as shown in FIG. 6, the ultraviolet light irradiation device 1 has a connection portion 31 into which the optical fiber 30 is inserted and connected to the side surface on the -X side of the cylindrical body portion 7, and a sealing portion 32 that seals the connection portion 31. The optical fiber 30 guides the incident laser light L1 into the housing portion 6.

[0108] From the viewpoint of increasing the illuminance of the ultraviolet light U1 emitted from the light emitting unit 8, it is preferable to increase the intensity of the laser light L1 incident on the NLO element 4. Here, to increase the intensity of the laser light L1, it is conceivable to increase the output of the laser light source 2. However, in this case, the laser light source 2 and the power supply unit 5 are likely to be enlarged. On the other hand, according to the present embodiment, the laser unit 20 equipped with the laser light source 2 and the housing unit 6 having the light emitting unit 8 are configured separately. Thereby, it becomes easy to increase the output of the laser light source 2 while configuring the housing unit 6 to be small.

[0109] Further, since the laser unit 20 and the housing unit 6 are configured separately, the design of the laser unit 20 is easy. The laser light source 2 may be a semiconductor laser, or may be a solid laser, a liquid laser, or a gas laser. The configuration of the laser light source 2 can be appropriately selected according to, for example, the required output of the laser light L1.

[0110] Further, the laser light L1 is light belonging to a wavelength range longer than 400 nm in terms of the main wavelength. Therefore, the laser light L1 is less likely to be attenuated when propagating through the optical fiber 30 as compared with the ultraviolet light U1. Therefore, as shown in FIG. 6, it is preferable to guide the laser light L1 through the optical fiber 30 and then make the laser light L1 incident on the NLO element 4 to obtain the ultraviolet light U1.

[0111] FIG. 7 is an enlarged view showing in more detail the configuration of the connection portion 31 of the ultraviolet light irradiation device 1 according to FIG. 6. With reference to FIG. 7, the configuration of the sealing portion 32 and the optical fiber 30 will be described.

[0112] As shown in Fig. 7, the sealing portion 32 is composed of a ring-shaped sealing member 33 disposed between the cylindrical body portion 7 and the optical fiber 30, and a fixing member 34 for fixing the optical fiber 30 at a predetermined position. As an example, the sealing member 33 is an O-ring made of a rubber material such as nitrile rubber, silicone rubber, or fluororubber. Further, the fixing member 34 is, for example, in a cylindrical shape and has a spiral groove 34a on its inner peripheral surface. The fixing member 34 is integrated with the cylindrical body portion 7 by, for example, welding or the like. Note that the joining method between the fixing member 34 and the cylindrical body portion 7 is arbitrary.

[0113] As shown in Fig. 7, the optical fiber 30 has a propagation portion 35, a coating portion 36, and a connecting portion 37. The propagation portion 35 includes a core layer and a cladding layer, and propagates the incident laser beam L1. The coating portion 36 is, for example, made of a silicone resin and coats the propagation portion 35.

[0114] The connecting portion 37 is disposed around the coating portion 36 and has a spiral groove 37a on its outer peripheral surface. The groove 37a is engaged with the groove 34a of the fixing member 34.

[0115] By inserting the connecting portion 37 into the fixing member 34 through the spiral grooves (34a, 37a), the sealing member 33 is brought into contact with the optical fiber 30 and the cylindrical body portion 7. Thereby, the sealing portion 32 seals the connection portion 31.

[0116] When the optical fiber 30 is inserted into the connection portion 31 and the sealing member 33 such as an O-ring is not disposed, it is assumed that the external atmosphere enters the housing portion 6 through a slight gap existing between the connection portion 31 and the optical fiber 30. On the other hand, as described with reference to Fig. 7, by the sealing portion 32 sealing the connection portion 31, a closed space S1 can be formed in the housing portion 6. Thereby, while the laser unit 20 and the housing portion 6 are configured separately, the NLO element 4 can be disposed in the closed space S1 to suppress the deterioration of the NLO element 4.

[0117] In addition, by the sealing portion 32 sealing the connection portion 31, a decrease in the airtightness of the housing portion 6 due to connecting the optical fiber 30 to the housing portion 6 is suppressed. That is, the present embodiment is also suitable when the closed space S1 is a space hermetically sealed from the outside.

[0118] Note that the configuration of the sealing portion 32 shown in FIG. 7 is an example, and the configuration of the sealing portion 32 is arbitrary as long as it can seal the connection portion 31.

[0119] Also, in FIG. 6, as described with reference to FIG. 4, the protective film 12 may be disposed on the surface of the NLO element 4. Thereby, with the laser unit 20 and the housing portion 6 configured separately, the NLO element 4 can be disposed in a space hermetically sealed from the external space.

[0120] As an added precaution, regarding the configurations according to FIGS. 6 and 7, when verifying the airtightness of the space in which the NLO element 4 is disposed by the above-described method and placing the housing portion 6 in a predetermined humidity environment, the optical fiber 30 may be appropriately removed from the laser unit 20. Further, during the verification, it is preferable that the influence of deterioration of the optical fiber 30 due to disposing the optical fiber 30 in a predetermined humidity environment is suppressed. For this reason, the optical fiber 30 may be appropriately replaced with one of the same specifications during the verification.

[0121] [Modification Example] Hereinafter, a modification example of the ultraviolet light irradiation device 1 will be described.

[0122] 〈1〉 FIG. 8A is a cross-sectional view showing a modification example of the light emitting portion 8. From the viewpoint of facilitating insertion of the light emitting portion 8 into a narrow region, the light emitting portion 8 may have a shape in which the outer diameter decreases as it advances in the +X direction.

[0123] <2> Further, FIG. 8B is a cross-sectional view showing another modification of the light emitting portion 8. As shown in FIG. 8B, the light emitting portion 8 may be configured to cover the opening 10 (not shown in FIG. 8B, see FIG. 1B) while being in contact with the outer wall 7b in the Z direction of the cylindrical body portion 7. By the light emitting portion 8 coming into contact with the outer wall 7b, it becomes difficult to form a gap between the light emitting portion 8 and the outer wall 7b, and it becomes easy to form the closed space S1.

[0124] <3> FIG. 9 is a cross-sectional view showing a modification of the housing portion 6. In order to facilitate irradiation of the irradiation target region W1 in a narrow region such as inside the oral cavity with the ultraviolet light U1, as shown in FIG. 9, the housing portion 6 may include a light guide portion 25.

[0125] As shown in FIG. 9, the light guide portion 25 has a bent shape and guides the ultraviolet light U1 by connecting the cylindrical body portion 7 and the light emitting portion 8. By the inner surface of the light guide portion 25 being configured to reflect the ultraviolet light U1, the ultraviolet light U1 is guided to the light emitting portion 8. The light guide portion 25 can be made of a metal material such as aluminum or stainless steel. Further, a reflective film made of the above metal material may be formed on the inner surface of the light guide portion 25, or a reflecting member 26 that reflects the ultraviolet light U1 may be disposed inside the light guide portion 25.

[0126] Further, FIG. 10 is a cross-sectional view showing another modification of the housing portion 6. FIG. 10 shows an example in which the laser light L1 is guided to the light guide portion 25 via the optical fiber 30 described with reference to FIG. 6. Note that the illustration of the laser unit 20 and the optical system 3 is omitted in FIG. 10. As shown in FIG. 10, the reflecting member 26 and the NLO element 4 may be disposed inside the light guide portion 25.

[0127] The reflecting member 26 has a reflecting surface that reflects the laser light L1. The reflecting member 26 may be made of a metal material such as aluminum or stainless steel, or may be made of a member having a reflective film made of the above metal material. Further, the reflecting member 26 may be made of a glass material such as quartz glass and guide the laser light L1 by total reflection.

[0128] As shown in Fig. 10, by changing the traveling direction of the laser beam L1 with the reflecting member 26 and making the laser beam L1 incident on the NLO element 4 disposed on the tip side of the light guiding part 25, ultraviolet light U1 can be obtained as close as possible to the light emitting part 8.

[0129] From the viewpoint of suppressing the attenuation or divergence of the ultraviolet light U1 due to reflection by the reflecting member 26, as shown in Fig. 10, it is preferable to adopt a configuration in which the laser beam L1 is made incident on the reflecting member 26 and the reflected light thereof is made incident on the NLO element 4.

[0130] According to the apparatuses of Figs. 9 and 10, by inserting the light emitting part 8 into the oral cavity, the ultraviolet light U1 can be efficiently irradiated onto the irradiation target region W1 in the oral cavity. Further, for example, during dental treatment, a cleaning liquid is appropriately supplied into the oral cavity, and since the NLO element 4 is disposed on the tip side of the light guiding part 25, an effect of cooling the NLO element 4 by the cleaning liquid can be expected, which is preferable.

[0131] 〈4〉 It is preferable that the irradiation range of the ultraviolet light U1 can be changed according to the range of the irradiation target region W1. Fig. 11 is a cross-sectional view showing a modified example of the ultraviolet light irradiation device 1. As shown in Fig. 11, the ultraviolet light irradiation device 1 has a diffusion member 40 on the +X side of the light emitting part 8. The diffusion member 40 is made of a material that exhibits diffusibility with respect to the ultraviolet light U1. Examples of such a material include fluorine-based resins such as PTFE.

[0132] As shown in Fig. 11, by attaching the diffusion member 40 to the light emitting part 8, the ultraviolet light U1 is diffused, and as a result, the irradiation range of the ultraviolet light U1 is changed. The diffusion member 40 is preferably configured to be detachable from the light emitting part 8. By switching between the state where the diffusion member 40 is attached to the light emitting part 8 and the state where the diffusion member 40 is removed, the irradiation range of the ultraviolet light U1 can be easily changed.

[0133] As an example, the diffusion member 40 is configured to be slidable by an arbitrary slide mechanism, and the mounting state with respect to the light emitting unit 8 is configured to be switchable. More specifically, the ultraviolet light irradiation device 1 may include an electric motor (not shown) disposed at the operator's hand, and a shaft (not shown) that connects the electric motor and the diffusion member 40. By moving the shaft by driving the electric motor, the diffusion member 40 may be slid, and the mounting state of the diffusion member 40 with respect to the light emitting unit 8 may be switched.

[0134] The electric motor may be controlled by an electric signal or a switch disposed at the operator's hand. Thereby, the irradiation range of the ultraviolet light U1 can be easily changed, which is preferable.

[0135] The diffusion member 40 may be configured to be attachable to the light emitting unit 8 by a method such as screwing. That is, the means for switching the mounting state of the diffusion member 40 with respect to the light emitting unit 8 is not limited to the above and is arbitrary.

[0136] 〈5〉 In FIGS. 4 and 5, an example in which the protective film 12 covers the NLO element 4 is shown from the viewpoint of disposing the NLO element 4 in a hermetically sealed space. However, the present invention does not exclude a configuration in which the protective film 12 is disposed on one side surface of the NLO element 4. For example, the protective film 12 may be disposed on the side surface related to the -Y side and the side surface related to the -Z side of the NLO element 4.

[0137] 〈6〉 The ultraviolet light irradiation device 1 can be incorporated into a medical device such as an endoscope. For example, a light emitting unit 8 may be provided at the tip of the scope of an endoscope inserted into the abdominal cavity, and the NLO element 4 may be disposed in the scope. By guiding the laser light L1 to the NLO element 4 through an optical fiber built in the scope, the ultraviolet light U1 can be suitably irradiated to the irradiation target region W1 while observing the inside of the abdominal cavity. Further, during the treatment, a perfusion fluid such as physiological saline is appropriately fed from the tip of the scope. By disposing the NLO element 4 at the tip of the scope, an effect of cooling the NLO element 4 by the perfusion fluid can also be expected.

[0138] 〈7〉 In the above description, the cylindrical body portion 7 has been described as being made of a material with low water vapor permeability. However, the constituent material of the cylindrical body portion 7 is not limited to the above. Similarly, the constituent material of the light emitting portion 8 is also not limited to the above. That is, the constituent material of the housing portion 6 is arbitrary as long as the housing portion 6 can form a closed space.

[0139] Also, the method for verifying the airtightness of the space in which the NLO element 4 such as the housing portion 6 is disposed is as described above.

[0140] 〈8〉 The above-described embodiments and modifications can be realized by being appropriately combined.

Explanation of Reference Numerals

[0141] 1: Ultraviolet light irradiation device 2: Laser light source 3: Optical system 3a: Collimator lens 3b: Condensing lens 4: Nonlinear optical crystal element 5: Power supply unit 6: Housing portion 7: Cylindrical body portion 8: Light emitting portion 9: Holding member 12: Protective film 16: Housing portion 17: Cylindrical body portion 18: Light transmitting portion 20: Laser unit 21: Collimator lens 22: Condensing lens 25: Light guiding portion 26: Reflecting member 30: Optical fiber 31: Connection portion 32: Sealing portion 33: Sealing member 34: Fixing member 34a, 37a: Groove 35: Propagation portion 36: Coating portion 37: Connecting portion 40: Diffusion member

Claims

1. A laser light source that emits first light whose main wavelength belongs to a range longer than 400 nm, an optical system that reduces the divergence angle of the first light emitted from the laser light source, a non-linear optical crystal element into which the first light transmitted through the optical system is incident and that converts the first light into second light whose main wavelength belongs to a range of 200 nm to 235 nm and emits the converted light, and a first housing portion in which at least the optical system and the non-linear optical crystal element are disposed and that forms a closed space that isolates the optical system and the non-linear optical crystal element from the external space. The ultraviolet light irradiation device, wherein the first housing portion has a light emission portion that transmits the second light through a part of a side surface and emits the light to the outside.

2. The ultraviolet light irradiation device according to claim 1, wherein the non-linear optical crystal element is disposed in a space hermetically sealed from the external space.

3. The ultraviolet light irradiation device according to claim 2, further comprising a protective film that covers a surface of the non-linear optical crystal element and transmits the first light and the second light.

4. The ultraviolet light irradiation device according to claim 2, further comprising a second housing portion that is disposed in the closed space formed by the first housing portion and that has a light transmission portion that transmits the second light through a part of a side surface, wherein the second housing portion houses the optical system, the non-linear optical crystal element, and the laser light source therein and isolates the optical system, the non-linear optical crystal element, and the laser light source from a space outside the second housing portion in the closed space, and the light transmission portion is disposed between the non-linear optical crystal element and the light emission portion with respect to a traveling direction of the second light.

5. A laser unit on which the laser light source is mounted, and an optical fiber that is connected to the laser unit and guides the first light emitted from the laser light source into the first housing portion. A connection part provided at a partial location on the side surface of the first accommodating part, to which the optical fiber is connected, and a sealing part for sealing the connection part, and the ultraviolet light irradiation device according to claim 1 or 2, characterized in that it comprises the same.

6. Regarding the path through which at least one of the first light and the second light travels, the distance from the non-linear optical crystal element to the light emitting part is shorter than the distance from the laser light source to the non-linear optical crystal element, and the ultraviolet light irradiation device according to claim 1 or 2, characterized in that it is the same.

7. Regarding the direction in which the light emitting part emits the second light, the separation distance between the non-linear optical crystal element and the light emitting part is within 10 cm, and the ultraviolet light irradiation device according to claim 1 or 2, characterized in that it is the same.

8. The light emitting part is made of a material that exhibits diffusibility with respect to the second light, and the ultraviolet light irradiation device according to claim 1 or 2, characterized in that it is the same.

9. It comprises a diffusion member made of a material that exhibits diffusibility with respect to the second light and is configured to be attachable to the light emitting part, and the ultraviolet light irradiation device according to claim 1 or 2, characterized in that it is the same.

10. It comprises a holding member for holding the non-linear optical crystal element in a state where the non-linear optical crystal element is in communication with the inner wall of the first accommodating part, The holding member is made of one or more materials selected from the group consisting of copper, silver, aluminum, and brass, and the ultraviolet light irradiation device according to claim 1 or 2, characterized in that it is the same.

11. When the light emitting part is viewed from a direction opposite to the direction in which the light emitting part emits the second light, the maximum width of the light emitting part is 20 mm or less, and the ultraviolet light irradiation device according to claim 1 or 2, characterized in that it is the same.

12. The light emitting part is inserted into the body of an animal and is configured to be able to irradiate the second light into the body, and the ultraviolet light irradiation device according to claim 1 or 2, characterized in that it is the same.

13. Step (a) of irradiating a first light whose main wavelength belongs to a range longer than 400 nm onto a nonlinear optical crystal element disposed in a closed space to obtain a second light whose main wavelength belongs to a range of 200 nm to 235 nm; Step (b) of irradiating an irradiation target region with the second light emitted from the closed space, wherein the ultraviolet light irradiation method is characterized by comprising the steps.

14. The ultraviolet light irradiation method according to claim 13, wherein the step (b) is a step of irradiating the irradiation target region in the body of an animal with the second light.

15. The ultraviolet light irradiation method according to claim 13 or 14, wherein the step (a) is a step of irradiating the first light onto the nonlinear optical crystal element disposed in a hermetically sealed space.

16. The ultraviolet light irradiation method according to claim 13 or 14, wherein the step (a) includes a step of generating the second light in the vicinity of the irradiation target region.

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