EP4657498A1

EP4657498A1 - Light-emitting sealed body

Info

Publication number: EP4657498A1
Application number: EP23935461.6A
Authority: EP
Inventors: Akio Suzuki; Masaru SHIMOMAKI; Yu MATSUSHIRO; Kohei Sugitani
Original assignee: Hamamatsu Photonics KK
Current assignee: Hamamatsu Photonics KK
Priority date: 2023-04-27
Filing date: 2023-12-21
Publication date: 2025-12-03
Also published as: WO2024224690A1; TW202443633A; JP2024158401A; CN121039781A; JP7462815B1

Abstract

A light-emitting sealed body includes a housing including a first window configured to cause first light to be incident on the plasma region, and a second window configured to cause second light to be emitted from the plasma region, and an enclosure defining an enclosed space including the plasma region and having a first opening corresponding to the first window and a second opening corresponding to the second window. The first window is positioned on an opposite side to the enclosed space with respect to an open end of the first opening on the enclosed space side, and the second window is positioned on an opposite side to the enclosed space with respect to an open end of the second opening on the enclosed space side. At least one of the first opening and the second opening is narrowed with respect to the enclosed space.

Description

Technical Field

The present disclosure relates to a light-emitting sealed body applied to, for example, a laser excitation light source.

Background Art

As a light-emitting sealed body applied to a laser excitation light source, there is known a light-emitting sealed body including a housing that houses a gas for generating plasma, and an enclosure that defines an enclosed space including a plasma region in the housing. The housing includes a laser beam incidence window for causing a laser beam for maintaining the plasma to be incident on the plasma region and a plasma light emission window for emitting plasma light emitted from the plasma from the plasma region (see, for example, Patent Literature 1).

Citation List

Patent Literature

Patent Literature 1: Specification of US Patent No. 10008378

Summary of Invention

Technical Problem

In the light-emitting sealed body described above, since a space where the gas convects is narrowed as compared with a case where the enclosure is not disposed in the housing, the convection in the gas is less likely to occur in the space. When the convection in the gas becomes strong, since an adverse effect such as a noise component being added to the plasma light emitted to an outside of the housing occurs, the convection in the gas is suppressed, and thus, deterioration in quality of output light is suppressed. However, in order to improve performance of a device using the light source, it is required to further improve the quality of the output light.
An object of the present disclosure is to provide a light-emitting sealed body capable of improving quality of output light.

Solution to Problem

A light-emitting sealed body according to one aspect of the present disclosure is [1] "a light-emitting sealed body including a housing that houses a gas for generating plasma, the housing including a first window configured to cause first light for maintaining the plasma in a plasma region where the plasma is generated to be incident on the plasma region, and a second window configured to emit second light emitted from the plasma from the plasma region, and an enclosure defining an enclosed space including the plasma region in the housing and having a first opening corresponding to the first window and a second opening corresponding to the second window, in which the first window is positioned on an opposite side to the enclosed space with respect to an open end of the first opening on the enclosed space side, the second window is positioned on an opposite side to the enclosed space with respect to an open end of the second opening on the enclosed space side, and at least one of the first opening and the second opening is narrowed with respect to the enclosed space".
In the light-emitting sealed body according to the above [1], the enclosed space including the plasma region is defined by the enclosure in the housing. As a result, since the space where the gas convects is narrowed as compared with a case where the enclosure is not disposed in the housing, it is possible to suppress the occurrence of the convection in the gas in the space. Further, at least one of the first opening and the second opening is narrowed with respect to the enclosed space in the enclosure. As a result, since the gas in the enclosed space is less likely to be influenced by the environment outside the housing as compared with a case where both the first opening and the second opening are not narrowed with respect to the enclosed space, it is possible to suppress the occurrence of the convection in the gas due to the environment outside the housing. Thus, according to the light-emitting sealed body according to the above [1], it is possible to improve the quality of the output light.
The light-emitting sealed body according to one aspect of the present disclosure may be [2] "the light-emitting sealed body according to the above [1], in which the enclosure is made of an insulating material". In accordance with the light-emitting sealed body described in the above [2], since the space where the gas convects is enclosed by the insulating enclosure, the plasma can be stably maintained without influencing the plasma by the enclosure.
The light-emitting sealed body according to one aspect of the present disclosure may be [3] "the light-emitting sealed body according to the above [1] or [2], in which the second opening is a tapered opening in which the open end of the second opening on the enclosed space side is smaller than an open end of the second opening on an opposite side to the enclosed space". In accordance with the light-emitting sealed body described in the above [3], it is possible to efficiently emit the second light emitted radially to the outside of the housing via the second opening and the second window while narrowing the second opening with respect to the enclosed space in the enclosure.
The light-emitting sealed body according to one aspect of the present disclosure may be [4] "the light-emitting sealed body according to any one of the above [1] to [3], in which the enclosure includes a first enclosing member and a second enclosing member that are formed separately from each other, the first enclosing member defines the first opening, and the second enclosing member defines the second opening". In accordance with the light-emitting sealed body described in the above [4], the enclosure having a preferable shape for suppressing the occurrence of the convection can be accurately formed.
The light-emitting sealed body according to one aspect of the present disclosure may be [5] "the light-emitting sealed body according to any one of the above [1] to [4], in which an inner surface of the enclosure includes a region having a smooth concave surface shape, and at least one of the first opening and the second opening is opened in the region". In accordance with the light-emitting sealed body described in the above [5], since it is possible to smoothly move the gas near the smooth concave region, the influence of the convection on the plasma can be suppressed, and the plasma can be stably maintained.
The light-emitting sealed body according to one aspect of the present disclosure may be [6] "the light-emitting sealed body according to any one of the above [1] to [5], in which a part of the second window is positioned inside the second opening". In accordance with the light-emitting sealed body described in the above [6], it is possible to suppress the occurrence of the convection in the gas in the enclosed space as compared with a case where the entire second window is positioned outside the second opening.
The light-emitting sealed body according to one aspect of the present disclosure may be [7] "the light-emitting sealed body according to any one of the above [1] to [6], in which a region of an inner surface of the enclosure facing the first window with the plasma region interposed therebetween is a region having a smooth concave surface shape". In accordance with the light-emitting sealed body described in the above [7], since it is possible to smoothly move the gas generated between the region having the smooth concave surface shape and the plasma region along with the incidence of the first light for maintaining the plasma, the influence of the convection on the plasma can be suppressed, and the plasma can be stably maintained.

Advantageous Effects of Invention

In accordance with the present disclosure, it is possible to provide the light-emitting sealed body capable of improving the quality of the output light.

Brief Description of Drawings

FIG. 1 is a sectional view of a light-emitting sealed body of a first embodiment.
FIG. 2 is a sectional view of the light-emitting sealed body taken along line II-II illustrated in FIG. 1.
FIG. 3 is a sectional view of the light-emitting sealed body taken along line III-III illustrated in FIG. 1.
FIG. 4 is a sectional view of a light-emitting sealed body of a second embodiment.
FIG. 5 is a sectional view of the light-emitting sealed body taken along line V-V illustrated in FIG. 4.
FIG. 6 is a sectional view of the light-emitting sealed body taken along line VI-VI illustrated in FIG. 4.
FIG. 7 is a sectional view of a light-emitting sealed body of a third embodiment.
FIG. 8 is a sectional view of the light-emitting sealed body taken along line VIII-VIII illustrated in FIG. 7.
FIG. 9 is a sectional view of the light-emitting sealed body taken along line IX-IX illustrated in FIG. 7.
FIG. 10 is a sectional view of a light-emitting sealed body of a fourth embodiment.
FIG. 11 is a sectional view of the light-emitting sealed body taken along line XI-XI illustrated in FIG. 10.
FIG. 12 is a sectional view of the light-emitting sealed body taken along line XII-XII illustrated in FIG. 10.
FIG. 13 is a sectional view of a light-emitting sealed body of a fifth embodiment.
FIG. 14 is a sectional view of the light-emitting sealed body taken along line XIV-XIV illustrated in FIG. 13.
FIG. 15 is a sectional view of the light-emitting sealed body taken along line XV-XV illustrated in FIG. 13.

Description of Embodiments

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that, in the drawings, the same or corresponding parts are denoted by the same reference signs, and redundant description will be omitted.

[First Embodiment]

As illustrated in FIGS. 1, 2, and 3, a light-emitting sealed body 1A of a first embodiment includes a housing 2, a first electrode 3, a second electrode 4, a first holder 5, an enclosure 7, and an encapsulation tube 8. The housing 2 houses a gas G for generating plasma. The gas G is, for example, xenon gas. In the light-emitting sealed body 1A, a laser beam (first light) L1 for maintaining plasma is incident on a plasma region R (region where plasma is generated in the gas G), and plasma light (second light) L2 emitted from the plasma is emitted from the plasma region R. Note that, although the plasma light L2 emitted from the plasma is actually radiationally generated in all directions around the plasma region R, only the plasma light L2 as output light is illustrated for the sake of convenience. A wavelength of the laser beam L1 is, for example, about 800 nm to 1100 nm, and a wavelength of the plasma light L2 is, for example, about 120 nm to 20 µm. The light-emitting sealed body 1A is a device applied to a laser excitation light source.
The housing 2 includes a main body 20, a laser beam incidence window (first window) 10A, and two plasma light emission windows (second windows) 10B and 10C. The main body 20 is a substantially rectangular parallelepiped member. In the main body 20, a housing space 21, three window openings 22, 23, and 24, and two electrode openings 26 and 27 are formed. The housing space 21 includes the plasma region R. The window opening 22 is opened to one side in the Z-axis direction from the housing space 21. The window opening 23 is opened to one side in an X-axis direction (a direction perpendicular to the Z-axis direction) from the housing space 21. The window opening 24 is opened to the other side in the X-axis direction from the housing space 21. The electrode opening 26 is opened to one side in a Y-axis direction (a direction perpendicular to both the Z-axis direction and the X-axis direction) from the housing space 21. The electrode opening 27 is opened to the other side in the Y-axis direction from the housing space 21. A material of the main body 20 is, for example, metal such as stainless steel.
The laser beam incidence window 10A airtightly seals the window opening 22. The laser beam incidence window 10A causes the laser beam L1 to be incident on the plasma region R. In the light-emitting sealed body 1A, the laser beam incidence window 10A causes the laser beam L1 to be incident on the plasma region R along an optical axis A1 parallel to the Z-axis direction. In other words, an optical axis of the laser beam L1 is A1.
The laser beam incidence window 10A includes the window member 11 and the holding member 12. The window member 11 is formed in a plate shape with the optical axis A1 as a center line and the Z-axis direction as a thickness direction. The window member 11 transmits the laser beam L1. A material of the window member 11 is a light transmissive material having a light transmission property at least for a wavelength of the laser beam L1, and is, for example, sapphire. The holding member 12 is formed in a tubular shape with the optical axis A1 as the center line. The window member 11 is held by the holding member 12 in a state of being disposed inside the holding member 12. A material of the holding member 12 is, for example, a metal material such as Kovar. The side surface of the window member 11 is airtightly joined to an inner surface of the holding member 12 by a joining material such as a metal brazing material. An outer surface of the holding member 12 is airtightly joined to an inner surface of the window opening 22 by, for example, laser welding.
The plasma light emission window 10B airtightly seals the window opening 23. The plasma light emission window 10B emits the plasma light L2 on one side in the X-axis direction from the plasma region R. The plasma light emission window 10C airtightly seals the window opening 24. The plasma light emission window 10C emits the plasma light L2 to the other side in the X-axis direction from the plasma region R. In the light-emitting sealed body 1A, each of the plasma light emission windows 10B and 10C emits the plasma light L2 from the plasma region R along an optical axis A2 parallel to the X-axis direction. In other words, an optical axis of the plasma light L2 is A2. Note that, the optical axis A1 and the optical axis A2 intersect at a center of the plasma region R, and intersect vertically in the present embodiment.
The plasma light emission window 10B has a window member 13 and a holding member 14. The window member 13 is formed in a plate shape with the optical axis A2 as a center line and the X-axis direction as a thickness direction. The window member 13 transmits the plasma light L2. A material of the window member 13 is a light transmissive material having a light transmission property at least for the wavelength of the plasma light L2, and is, for example, diamond, sapphire, or magnesium fluoride. The holding member 14 is formed in a tubular shape with the optical axis A2 as the center line. The window member 13 is held by the holding member 14 in a state of being disposed inside the holding member 14. A material of the holding member 14 is, for example, a metal material such as Kovar. The side surface of the window member 13 is airtightly joined to an inner surface of the holding member 14 by a joining material such as a metal brazing material. An outer surface of the holding member 14 is airtightly joined to an inner surface of the window opening 23 by, for example, laser welding.
The plasma light emission window 10C has the window member 15 and a holding member 16. The window member 15 is formed in a plate shape with the optical axis A2 as a center line and the X-axis direction as a thickness direction. The window member 15 transmits the plasma light L2. A material of the window member 15 is a light transmissive material having a light transmission property at least for the wavelength of the plasma light L2, and is, for example, diamond, sapphire, or magnesium fluoride. The holding member 16 is formed in a tubular shape with the optical axis A2 as the center line. The window member 15 is held by the holding member 16 in a state of being disposed inside the holding member 16. A material of the holding member 16 is, for example, a metal material such as Kovar. The side surface of the window member 15 is airtightly joined to an inner surface of the holding member 16 by a joining material such as a metal brazing material. An outer surface of the holding member 16 is airtightly joined to an inner surface of the window opening 24 by, for example, laser welding.
The first electrode 3 extends from the outside of the housing 2 into an enclosed space 73 defined by the enclosure 7 via the electrode opening 26 of the housing 2 and an electrode opening 78 of the enclosure 7 to be described later. In the light-emitting sealed body 1A, the first electrode 3 is a rod-shaped member extending in the Y-axis direction. A material of the first electrode 3 is, for example, a metal material having a high melting point such as tungsten. A distal end (first distal end) 31 of the first electrode 3 faces the plasma region R in the housing 2. In the light-emitting sealed body 1A, the distal end 31 of the first electrode 3 faces the plasma region R in the enclosed space 73 and is enclosed by the enclosure 7.
The first holder 5 is an insulating member extending along the Y-axis direction, and holds the first electrode 3. A material of the first holder 5 is an insulating material having high temperature resistance, and is, for example, ceramic. The first holder 5 includes a main body 51 and tubular portions 52 and 55. The tubular portion 52 is positioned on an opposite side to the plasma region R with respect to the main body 51, and the tubular portion 55 is positioned on the plasma region R side with respect to the main body 51. The main body 51 and the tubular portion 52 are disposed outside the electrode opening 26 of the housing 2, and the tubular portion 55 is disposed inside the electrode opening 26 of the housing 2. A through-hole 51a penetrating the main body 51 along the Y-axis direction is formed in the main body 51. The through-hole 51a is opened to an inside of each of the tubular portions 52 and 55. The intermediate portion 32 of the first electrode 3 is disposed in the through-hole 51a. The side surface of the intermediate portion 32 is airtightly joined to the inner surface of the through-hole 51a by a joining material such as a metal brazing material. The proximal end 33 of the first electrode 3 is disposed inside the tubular portion 52.
The first holder 5 is fixed to the housing 2. In the light-emitting sealed body 1A, the first holder 5 is fixed to the housing 2 via a tubular connection member 9A. The connection member 9A includes a tubular portion 91A and an inward flange 92A. The inward flange 92A is provided at an end of the tubular portion 91A on an opposite side to the housing 2. A material of the connection member 9A is, for example, a metal material such as Kovar. The inward flange 92A is airtightly joined to an outward flange 53 provided in the main body 51 of the first holder 5 by a joining material such as a metal brazing material. An end of the tubular portion 91A on the housing 2 side is airtightly joined to the housing 2 by, for example, laser welding.
The second electrode 4 extends from an inside of the electrode opening 27 of the housing 2 into the enclosed space 73 defined by the enclosure 7 via an electrode opening 79 of the enclosure 7 to be described later. In the light-emitting sealed body 1A, the second electrode 4 is a rod-shaped member extending in the Y-axis direction. A material of the second electrode 4 is, for example, a metal material having a high melting point such as tungsten. The distal end 41 of the second electrode 4 faces the plasma region R in the housing 2, and faces the distal end 31 of the first electrode 3 with the plasma region R interposed therebetween. In the light-emitting sealed body 1A, the distal end 41 of the second electrode 4 faces the plasma region R in the enclosed space 73 and is enclosed by the enclosure 7. A side surface of the proximal end 43 of the second electrode 4 is airtightly joined to the inner surface of the electrode opening 27 by a joining material such as a metal brazing material.
The enclosure 7 is an insulating member disposed in the housing space 21 of the housing 2. In the enclosure 7, the enclosed space 73, three light passage openings 74, 75, and 76, and two electrode openings 78 and 79 are formed.
The enclosed space 73 includes the plasma region R. The light passage opening 74 is opened to one side in the Z-axis direction from the enclosed space 73. The light passage opening 75 is opened to one side in the X-axis direction from the enclosed space 73. The light passage opening 76 is opened to the other side in the X-axis direction from the enclosed space 73. The electrode opening 78 is opened to one side in the Y-axis direction from the enclosed space 73. The electrode opening 79 is opened to the other side in the Y-axis direction from the enclosed space 73.
The light passage opening (first opening) 74 corresponds to the laser beam incidence window 10A. That is, as viewed from a direction (the Z-axis direction in the light-emitting sealed body 1A) in which the plasma region R and the laser beam incidence window 10A are arranged, the light passage opening 74 overlaps the laser beam incidence window 10A. In the light-emitting sealed body 1A, a center line of the light passage opening 74 coincides with the center line of the window member 11 of the laser beam incidence window 10A (that is, coincides with the optical axis A1), and the light passage opening 74 is included in the window member 11 of the laser beam incidence window 10A as viewed from the Z-axis direction. The light passage opening 74 is narrowed with respect to the enclosed space 73. That is, as viewed from a direction (the Z-axis direction in the light-emitting sealed body 1A) in which the plasma region R and the light passage opening 74 are arranged, an open end 74a of the light passage opening 74 on the enclosed space 73 side is included in the enclosed space 73. In the light-emitting sealed body 1A, the light passage opening 74 is a step-shaped opening in which an open end 74a on the enclosed space 73 side is smaller than an open end 74b on an opposite side to the enclosed space 73. The window member 11 of the laser beam incidence window 10A is positioned outside the light passage opening 74.
The light passage opening (second opening) 75 corresponds to the plasma light emission window 10B. That is, as viewed from a direction (the X-axis direction in the light-emitting sealed body 1A) in which the plasma region R and the plasma light emission window 10B are arranged, the light passage opening 75 overlaps the plasma light emission window 10B. In the light-emitting sealed body 1A, a center line of the light passage opening 75 coincides with the center line of the window member 13 of the plasma light emission window 10B (that is, coincides with the optical axis A2), and the light passage opening 75 is included in the window member 13 of the plasma light emission window 10B as viewed from the X-axis direction. The light passage opening 75 is narrowed with respect to the enclosed space 73. That is, as viewed from a direction (the X-axis direction in the light-emitting sealed body 1A) in which the plasma region R and the light passage opening 75 are arranged, an open end 75a of the light passage opening 75 on the enclosed space 73 side is included in the enclosed space 73. In the light-emitting sealed body 1A, the light passage opening 75 is a tapered opening in which the open end 75a on the enclosed space 73 side is smaller than an open end 75b on an opposite side to the enclosed space 73. The window member 13 of the plasma light emission window 10B is positioned outside the light passage opening 75.
The light passage opening (second opening) 76 corresponds to the plasma light emission window 10C. That is, as viewed from a direction (the X-axis direction in the light-emitting sealed body 1A) in which the plasma region R and the plasma light emission window 10C are arranged, the light passage opening 76 overlaps the plasma light emission window 10C. In the light-emitting sealed body 1A, a center line of the light passage opening 76 coincides with the center line of the window member 15 of the plasma light emission window 10C (that is, coincides with the optical axis A2), and the light passage opening 76 is included in the window member 15 of the plasma light emission window 10C as viewed from the X-axis direction. The light passage opening 76 is narrowed with respect to the enclosed space 73. That is, as viewed from a direction (the X-axis direction in the light-emitting sealed body 1A) in which the plasma region R and the light passage opening 76 are arranged, an open end 76a of the light passage opening 76 on the enclosed space 73 side is included in the enclosed space 73. In the light-emitting sealed body 1A, the light passage opening 76 is a tapered opening in which the open end 76a on the enclosed space 73 side is smaller than an open end 76b on an opposite side to the enclosed space 73. The window member 15 of the plasma light emission window 10C is positioned outside the light passage opening 76.
The enclosure 7 includes a first enclosing member 7A and two second enclosing members 7B and 7C. The first enclosing member 7A and the two second enclosing members 7B and 7C are formed separately from each other. A material of each of the first enclosing member 7A and the two second enclosing members 7B and 7C is an insulating material having high temperature resistance, and is, for example, ceramic. In particular, in a case where a white ceramic is used, the amount of light extracted from the plasma light emission window 10B and the plasma light emission window 10C can be further increased by reflecting the plasma light L2. The first enclosing member 7A defines most of the enclosed space 73, the light passage opening 74, and the two electrode openings 78 and 79. The second enclosing member 7B defines the light passage opening 75 and a part of the enclosed space 73 on the light passage opening 75 side. The second enclosing member 7C defines the light passage opening 76 and a part of the enclosed space 73 on the light passage opening 76 side. Note that, at least a part of an outer surface shape of the enclosure 7 has a shape along an inner surface shape of the electrode opening 26 such that the enclosure 7 is easily introduced into a desired position of the housing space 21 at the time of manufacturing the light-emitting sealed body 1A. A part of an outer surface of the enclosure 7 abuts on an inner wall of the housing 2 that defines the housing space 21, so that the enclosure 7 is positioned in the housing space 21. The first enclosing member 7A and the two second enclosing members 7B and 7C are held by the housing 2 in a state of being combined with each other.
An inner surface 7a of the first enclosing member 7A includes a region S1 having a smooth concave surface shape. In the light-emitting sealed body 1A, a space surrounded by the region S1 has a columnar shape having a center line extending along the X-axis direction. As viewed from the X-axis direction, the region S1 has a circular shape with the plasma region R as a center. That is, a region of the inner surface 7a of the first enclosing member 7A facing the laser beam incidence window 10A with the plasma region R interposed therebetween is a part of the region S1 having the smooth concave surface shape. The light passage opening 74 and the two electrode openings 78 and 79 are opened in the region S1 of the inner surface 7a of the first enclosing member 7A. Note that, diameters of the electrode openings 78 and 79 are slightly larger than diameters of the first electrode 3 and the second electrode 4, respectively. The first enclosing member 7A is separated from the first electrode 3 and the second electrode 4 with a slight gap. A length of the gap is 1/5 or less of the diameters of the first electrode 3 and the second electrode 4. Thus, due to the gap, it is possible to suppress the influence of thermal expansion of each member, variations in accuracy and positioning of members, and the like without significantly influencing the trend of gas (occurrence of convection) in the enclosed space 73. The two second enclosing members 7B and 7C are disposed inside the first enclosing member 7A so as to sandwich the plasma region R along the X-axis direction. At this time, the second enclosing members 7B and 7C abut on a step portion provided inside the first enclosing member 7A, and thus, the second enclosing members 7B and 7C are positioned. Each of the second enclosing members 7B and 7C is a plate-shaped member with the X-axis direction as a thickness direction. In the housing space 21, the enclosed space 73 is enclosed by the inner surface 7a of the first enclosing member 7A, a side surface of the second enclosing member 7B on the plasma region R side, a side surface of the second enclosing member 7C on the plasma region R side, the three light passage openings 74, 75, and 76, and the two electrode openings 78 and 79. That is, the enclosure 7 defines the enclosed space 73 in the housing 2 and encloses the plasma region R in the housing 2.
An encapsulation hole 29 for encapsulating the gas G in the housing space 21 is formed in the main body 20 of the housing 2. The encapsulation tube 8 is connected to the encapsulation hole 29. A material of the encapsulation tube 8 is, for example, a metal material such as copper. An end of the encapsulation tube 8 on an opposite side to the encapsulation hole 29 is sealed. An outer surface of the encapsulation tube 8 is airtightly joined to an inner surface of the encapsulation hole 29 by a joining material such as a metal brazing material.
In the light-emitting sealed body 1A having the above-described configuration, in a case where the second electrode 4 is set to a ground potential, a negative voltage pulse or a positive voltage pulse is applied to the first electrode 3. As a result, arc discharge occurs in the gas G in the enclosed space 73, and plasma is generated between the first electrode 3 and the second electrode 4. At this time, the laser beam L1 is incident on the plasma region R from the laser beam incidence window 10A, and thus, the plasma is maintained in the plasma region R. Then, the plasma light L2 emitted from the plasma is emitted as the output light to the outside from the two plasma light emission windows 10B and 10C.
As described above, in the light-emitting sealed body 1A, the enclosed space 73 including the plasma region R is defined by the enclosure 7 in the housing 2. Accordingly, since a space where the gas G convects is narrowed as compared with a case where the enclosure 7 is not disposed in the housing 2, it is possible to suppress the occurrence of the convection in the gas G in the space. Further, in the enclosure 7, the three light passage openings 74, 75, and 76 are narrowed with respect to the enclosed space 73. As a result, as compared with a case where all the three light passage openings 74, 75, and 76 are not narrowed with respect to the enclosed space, since the gas G in the enclosed space 73 is less likely to be influenced by an environment outside the housing 2, it is possible to suppress the occurrence of the convection in the gas G due to the environment outside the housing 2. Thus, in accordance with the light-emitting sealed body 1A, it is possible to improve the quality of the output light. Further, the three light passage openings 74, 75, and 76 are narrowed with respect to the enclosed space 73 in the enclosure 7, and thus, it is possible to suppress passing of foreign matters through the three light passage openings 74, 75, and 76 to reach the laser beam incidence window 10A, the plasma light emission window 10B, and the plasma light emission window 10C, for example, even in a case where the first electrode 3 and the second electrode 4 are sputtered by the plasma and the foreign matters are generated, as compared with a case where all the three light passage openings 74, 75, and 76 are not narrowed with respect to the enclosed space. As a result, it is possible to suppress a problem such as a decrease in the amount of light due to contamination of each window and to maintain the quality of the output light.
In the light-emitting sealed body 1A, the enclosure 7 is made of an insulating material. As a result, since the space where the gas G convects is enclosed by the insulating enclosure 7, the plasma can be stably maintained without influencing the plasma by the enclosure 7. Further, since cooling of the gas G in the enclosed space 73 by the metal housing 2 can be suppressed, the convection can be stabilized, the influence of the convection on the plasma can be suppressed, and the plasma can be stably maintained. Further, since electric connection between the first electrode 3 and the second electrode 4 via the enclosure 7 can be suppressed, the plasma can be reliably generated.
In the light-emitting sealed body 1A, the light passage opening 75 is a tapered opening in which the open end 75a of the light passage opening 75 on the enclosed space 73 side is smaller than the open end 75b of the light passage opening 75 on an opposite side to the enclosed space 73. As a result, it is possible to efficiently emit the radially emitted plasma light L2 to the outside of the housing 2 via the light passage opening 75 and the plasma light emission window 10B while narrowing the light passage opening 75 with respect to the enclosed space 73 in the enclosure 7. In the light-emitting sealed body 1A, the light passage opening 76 is a tapered opening in which the open end 76a of the light passage opening 76 on the enclosed space 73 side is smaller than the open end 76b of the light passage opening 76 on an opposite side to the enclosed space 73. As a result, it is possible to efficiently emit the radially emitted plasma light L2 to the outside of the housing 2 via the light passage opening 76 and the plasma light emission window 10C while narrowing the light passage opening 76 with respect to the enclosed space 73 in the enclosure 7.
In the light-emitting sealed body 1A, the enclosure 7 has the first enclosing member 7A and the two second enclosing members 7B and 7C, and the first enclosing member 7A and the two second enclosing members 7B and 7C are formed separately from each other. The first enclosing member 7A defines the light passage opening 74, the second enclosing member 7B defines the light passage opening 75, and the second enclosing member 7C defines the light passage opening 76. As a result, the enclosure 7 having a preferable shape for suppressing the occurrence of the convection can be accurately formed. For example, since a shape of the enclosure 7 is complicated, it is difficult to integrally form the enclosure 7 with a single member, but the enclosure 7 can be accurately formed by dividing the enclosure 7 into the first enclosing member 7A and the two second enclosing members 7B and 7C. Since the three light passage openings 74, 75, and 76 can be accurately formed in the first enclosing member 7A and the two second enclosing members 7B and 7C, the light-emitting sealed body 1A having a desired optical axis with high accuracy can be obtained.
In the light-emitting sealed body 1A, the inner surface 7a of the first enclosing member 7A of the enclosure 7 includes the region S1 having the smooth concave surface shape, and the light passage opening 74 is opened in the region S1. As a result, since it is possible to smoothly move the gas near the region S1 having the smooth concave surface shape, the influence of the convection on the plasma can be suppressed, and the plasma can be stably maintained.
In the light-emitting sealed body 1A, the region of the inner surface 7a of the first enclosing member 7A of the enclosure 7 facing the laser beam incidence window 10A with the plasma region R interposed therebetween is the region S1 having the smooth concave surface shape. As a result, since it is possible to smoothly move the gas generated between the region S1 having the smooth concave surface shape and the plasma region R along with the incidence of the laser beam L1 for maintaining the plasma, the influence of the convection on the plasma can be suppressed, and the plasma can be stably maintained. In addition, even though the laser beam L1 transmitted through the plasma is incident on the inner surface 7a, since it is possible to suppress heading of the reflected light to the laser beam incidence window 10A, it is possible to suppress an adverse effect such as breakage of the laser by the reflected light.
In the light-emitting sealed body 1A, the laser beam incidence window 10A is positioned on an opposite side to the enclosed space 73 with respect to the open end 74a of the light passage opening 74 on the enclosed space 73 side. As a result, since the laser beam incidence window 10A is less likely to be influenced by charged particles generated in the plasma region R as compared with a case where the laser beam incidence window 10A is positioned in the enclosed space 73, damage to the laser beam incidence window 10A can be suppressed. In the light-emitting sealed body 1A, the plasma light emission window 10B is positioned on an opposite side to the enclosed space 73 with respect to the open end 75a of the light passage opening 75 on the enclosed space 73 side. As a result, since the plasma light emission window 10B is less likely to be influenced by charged particles generated in the plasma region R as compared with a case where the plasma light emission window 10B is positioned in the enclosed space 73, it is possible to suppress damage to the plasma light emission window 10B due to the charged particles. In the light-emitting sealed body 1A, the plasma light emission window 10C is positioned on an opposite side to the enclosed space 73 with respect to the open end 76a of the light passage opening 76 on the enclosed space 73 side. As a result, since the plasma light emission window 10C is less likely to be influenced by charged particles generated in the plasma region R as compared with a case where the plasma light emission window 10C is positioned in the enclosed space 73, it is possible to suppress damage to the plasma light emission window 10C due to the charged particles.

[Second Embodiment]

As illustrated in FIGS. 4, 5, and 6, a light-emitting sealed body 1B of a second embodiment is mainly different from the light-emitting sealed body 1A of the first embodiment in that both the two light passage openings 74 and 76 are opened in the region S1 having the smooth concave surface shape, of the inner surface 7a of the first enclosing member 7A, and the light passage opening 75 is opened in a region S2 having a smooth concave surface shape, of an inner surface 7b of the second enclosing member 7B. Hereinafter, the light-emitting sealed body 1B of the second embodiment will be described focusing on differences from the light-emitting sealed body 1A of the first embodiment.
The enclosure 7 includes the first enclosing member 7A and the second enclosing member 7B. The first enclosing member 7A and the second enclosing member 7B are formed separately from each other. A material of each of the first enclosing member 7A and the second enclosing member 7B is an insulating material having high temperature resistance, and is, for example, ceramic. In particular, in a case where a white ceramic is used, the amount of light extracted from the plasma light emission window 10B and the plasma light emission window 10C can be further increased by reflecting the plasma light L2. The first enclosing member 7A defines most of the enclosed space 73, the two light passage openings 74 and 76, and the two electrode openings 78 and 79. The second enclosing member 7B defines the light passage opening 75 and a part of the enclosed space 73 on the light passage opening 75 side. Note that, at least a part of the outer surface shape of the enclosure 7 has a shape along the inner surface shape of the electrode opening 26 such that the enclosure 7 is easily introduced into a desired position of the housing space 21 at the time of manufacturing the light-emitting sealed body 1B. A part of an outer surface of the enclosure 7 abuts on an inner wall of the housing 2 that defines the housing space 21, so that the enclosure 7 is positioned in the housing space 21. The first enclosing member 7A and the second enclosing member 7B are held by the housing 2 in a state of being combined with each other.
An inner surface 7a of the first enclosing member 7A includes a region S1 having a smooth concave surface shape. In the light-emitting sealed body 1B, the region S1 is a surface including a spherical surface. A space surrounded by a portion of the region S1 other than the spherical surface has a cylindrical shape. The light passage opening 76 is opened in a portion of the spherical surface of the region S1. The light passage opening 74 and the two electrode openings 78 and 79 are opened over the portion of the spherical surface of the region S1 and the portion of the region S1 other than the spherical surface. That is, the two light passage openings 74 and 76 are opened in the region S1. Note that, diameters of the electrode openings 78 and 79 are slightly larger than diameters of the first electrode 3 and the second electrode 4, respectively. The first enclosing member 7A is separated from the first electrode 3 and the second electrode 4 with a slight gap. A length of the gap is 1/5 or less of the diameters of the first electrode 3 and the second electrode 4. Thus, it is possible to suppress the influence of thermal expansion of each member, variations in accuracy and positioning of members, and the like without significantly influencing the trend of gas (occurrence of convection) in the enclosed space 73. The second enclosing member 7B is disposed inside the first enclosing member 7A so as to sandwich the plasma region R between the second enclosing member 7B and the first enclosing member 7A along the X-axis direction. At this time, the second enclosing member 7B abuts on the step portion provided inside the first enclosing member 7A, and thus, the second enclosing member 7B is positioned. The inner surface 7b of the second enclosing member 7B includes the region S2 having the smooth concave surface shape. In the light-emitting sealed body 1B, the region S2 is a spherical surface. The light passage opening 75 is opened in the region S1. The enclosed space 73 is enclosed by the inner surface 7a of the first enclosing member 7A, the inner surface 7b of the second enclosing member 7B, the three light passage openings 74, 75, and 76, and the two electrode openings 78 and 79 in the housing space 21. That is, the enclosure 7 defines the enclosed space 73 in the housing 2 and encloses the plasma region R in the housing 2.
As described above, in the light-emitting sealed body 1B, the inner surface 7a of the first enclosing member 7A of the enclosure 7 includes the region S1 having the smooth concave surface shape, and two light passage openings 74 and 76 are opened in the region S1. As a result, since it is possible to smoothly move the gas near the region S1 having the smooth concave surface shape, the influence of the convection on the plasma can be suppressed, and the plasma can be stably maintained.

[Third Embodiment]

As illustrated in FIGS. 7, 8, and 9, a light-emitting sealed body 1C of a third embodiment is mainly different from the light-emitting sealed body 1A of the first embodiment in that the housing 2 has a laser beam emission window 10D and the enclosure 7 has a laser beam passage window 10E. Hereinafter, the light-emitting sealed body 1C of the third embodiment will be described focusing on differences from the light-emitting sealed body 1A of the first embodiment.
The housing 2 includes the main body 20, the laser beam incidence window 10A, the plasma light emission window 10C, and the laser beam emission window 10D. In the main body 20, the housing space 21, three window openings 22, 24, and 25, and two electrode openings 26 and 27 are formed. The housing space 21 includes the plasma region R. The window opening 22 is opened to one side in the Z-axis direction from the housing space 21. The window opening 25 is opened to the other side in the Z-axis direction from the housing space 21. The window opening 24 is opened to one side in the X-axis direction from the housing space 21. The electrode opening 26 is opened to one side in the Y-axis direction from the housing space 21. The electrode opening 27 is opened to the other side in the Y-axis direction from the housing space 21.
The laser beam emission window 10D airtightly seals the window opening 25. The laser beam emission window 10D emits the laser beam L1 transmitted through the plasma from the plasma region R. In the present embodiment, in addition to the laser beam L1 transmitted through the plasma, the plasma light L2 emitted from the plasma region R to the laser beam emission window 10D side is also emitted, but is not illustrated for simplification of the drawing. Note that, an optical axis of the plasma light L2 emitted from the laser beam emission window 10D is coaxial with the laser beam L1. In the light-emitting sealed body 1C, the laser beam emission window 10D emits the laser beam L1 from the plasma region R along the optical axis A1. In other words, the emitted light emitted from the laser beam emission window 10D has an optical axis coaxial with the optical axis A1 of the laser beam L1.
The laser beam emission window 10D includes a window member 17 and a holding member 18. The window member 17 is formed in a plate shape with the optical axis A1 as a center line and the Z-axis direction as a thickness direction. The window member 17 transmits the laser beam L1. A material of the window member 17 is a light transmissive material having a light transmission property at least for the wavelength of the laser beam L1, and more preferably a light transmissive material having a light transmission property for the wavelength of the plasma light L2 in addition to the wavelength of the laser beam L1. In the present embodiment, the material of the window member 17 is a material having a light transmission property for the wavelengths of both the laser beam L1 and the plasma light L2, and is, for example, sapphire. The holding member 18 is formed in a tubular shape with the optical axis A1 as a center line. The window member 17 is held by the holding member 18 in a state of being disposed inside the holding member 18. A material of the holding member 18 is, for example, a metal material such as Kovar. The side surface of the window member 17 is airtightly joined to an inner surface of the holding member 18 by a joining material such as a metal brazing material. An outer surface of the holding member 18 is airtightly joined to an inner surface of the window opening 25 by, for example, laser welding.
The enclosure 7 has the laser beam passage window 10E. In the enclosure 7, the enclosed space 73, three light passage openings 74, 76, and 77, and two electrode openings 78 and 79 are formed. The enclosed space 73 includes the plasma region R. The light passage opening 74 is opened to one side in the Z-axis direction from the enclosed space 73. The light passage opening 77 is opened to the other side in the Z-axis direction from the enclosed space 73. The light passage opening 76 is opened to one side in the X-axis direction from the enclosed space 73. The electrode opening 78 is opened to one side in the Y-axis direction from the enclosed space 73. The electrode opening 79 is opened to the other side in the Y-axis direction from the enclosed space 73.
The light passage opening 77 corresponds to the laser beam emission window 10D. That is, as viewed from a direction (the Z-axis direction in the light-emitting sealed body 1C) in which the plasma region R and the laser beam emission window 10D are arranged, the light passage opening 77 overlaps the laser beam emission window 10D. In the light-emitting sealed body 1C, a center line of the light passage opening 77 coincides with the center line of the window member 17 of the laser beam emission window 10D (that is, coincides with the optical axis A1), and the light passage opening 77 is included in the window member 17 of the laser beam emission window 10D as viewed from the Z-axis direction. The light passage opening 77 is narrowed with respect to the enclosed space 73. That is, as viewed from a direction (the Z-axis direction in the light-emitting sealed body 1A) in which the plasma region R and the light passage opening 77 are arranged, an open end 77a of the light passage opening 77 on the enclosed space 73 side is included in the enclosed space 73. In the light-emitting sealed body 1C, the light passage opening 77 is a step-shaped opening in which the open end 77a on the enclosed space 73 side is smaller than an open end 77b on an opposite side to the enclosed space 73. The window member 17 of the laser beam emission window 10D is positioned outside the light passage opening 77.
The laser beam passage window 10E is disposed in the light passage opening 77. The laser beam passage window 10E faces the laser beam emission window 10D and faces the laser beam incidence window 10A with the plasma region R interposed therebetween. The laser beam passage window 10E emits the laser beam L1 transmitted through the plasma from the plasma region R. In the present embodiment, in addition to the laser beam L1 transmitted through the plasma, the plasma light L2 emitted from the plasma region R to the laser beam passage window 10E side is also emitted, but is not illustrated for simplification of the drawing. Note that, an optical axis of the plasma light L2 emitted from the laser beam passage window 10E is coaxial with the laser beam L1. In the light-emitting sealed body 1C, the laser beam passage window 10E emits the laser beam L1 from the plasma region R along the optical axis A1. In other words, the emitted light emitted from the laser beam passage window 10E has an optical axis coaxial with the optical axis A1 of the laser beam L1. The laser beam passage window 10E has an insulating window member 19. The window member 19 is formed in a plate shape with the optical axis A1 as a center line and the Z-axis direction as a thickness direction. The window member 19 transmits the laser beam L1. A material of the window member 19 is a light transmissive material having a light transmission property at least for the wavelength of the laser beam L1, and more preferably a light transmissive material having a light transmission property for the wavelength of the plasma light L2 in addition to the wavelength of the laser beam L1. In the present embodiment, the material of the window member 19 is a material having a light transmission property for the wavelengths of both the laser beam L1 and the plasma light L2, and is, for example, sapphire. A light passage region of the laser beam passage window 10E (a region through which the laser beam L1 passes) is defined by a wall 71b of the second enclosing member 7C having a light shielding property. In the light-emitting sealed body 1C, a light passage region of the window member 19 is defined by the wall 71b. In other words, as viewed from the direction (the Z-axis direction in the light-emitting sealed body 1C) in which the plasma region R and the light passage opening 77 are arranged, the light passage region of the window member 19 is enclosed by the wall 71b.
In the light-emitting sealed body 1C, the enclosure 7 includes the first enclosing member 7A, the second enclosing member 7C, and a third enclosing member 7D. The first enclosing member 7A, the second enclosing member 7C, and the third enclosing member 7D are formed separately from each other. The first enclosing member 7A defines the light passage opening 74 and a part of the enclosed space 73 on the light passage opening 74 side. The second enclosing member 7C defines most of the enclosed space 73, the light passage opening 76, and a part of the light passage opening 77 on the enclosed space 73 side. The third enclosing member 7D defines most of the light passage opening 77. A material of each of the first enclosing member 7A, the second enclosing member 7C, and the third enclosing member 7D is an insulating material having high temperature resistance, and is, for example, ceramic. In particular, in a case where a white ceramic is used, the amount of light extracted from the plasma light emission window 10C can be further increased by reflecting the plasma light L2. The window member 19 is sandwiched between the second enclosing member 7C and the third enclosing member 7D. The first enclosing member 7A, the second enclosing member 7C, and the third enclosing member 7D are held by the housing 2 in a state of being combined with each other together with the window member 19.
As described above, in the light-emitting sealed body 1C, the enclosure 7 includes the laser beam passage window 10E that emits the laser beam L1 transmitted through the plasma from the plasma region R. Accordingly, even though the space where the gas G convects is narrowed such that the convection in the gas G is less likely to occur, of the laser beam L1 incident on the space, the laser beam L1 transmitted through the plasma is transmitted through the laser beam passage window 10E. Thus, the enclosure 7 is less likely to be damaged by irradiation with the laser beam L1 transmitted through the plasma. Thus, in accordance with the light-emitting sealed body 1C, it is possible to achieve both the improvement in the quality of the output light and the improvement in the life of the device.

[Fourth Embodiment]

As illustrated in FIGS. 10, 11, and 12, a light-emitting sealed body 1D of a fourth embodiment is mainly different from the light-emitting sealed body 1A of the first embodiment in that a part of the plasma light emission window 10B is positioned inside the light passage opening 75 and a part of the plasma light emission window 10C is positioned inside the light passage opening 76. Hereinafter, the light-emitting sealed body 1D of the fourth embodiment will be described focusing on differences from the light-emitting sealed body 1A of the first embodiment.
In the enclosure 7, the enclosed space 73, three light passage openings 74, 75, and 76, and two electrode openings 78 and 79 are formed. The enclosed space 73 includes the plasma region R. The light passage opening 74 is opened to one side in the Z-axis direction from the enclosed space 73. The light passage opening 75 is opened to one side in the X-axis direction from the enclosed space 73. The light passage opening 76 is opened to the other side in the X-axis direction from the enclosed space 73. The electrode opening 78 is opened to one side in the Y-axis direction from the enclosed space 73. The electrode opening 79 is opened to the other side in the Y-axis direction from the enclosed space 73.
The light passage opening 75 is a step-shaped opening in which the open end 75a on the enclosed space 73 side is smaller than the open end 75b on an opposite side to the enclosed space 73. The light passage opening 76 is a step-shaped opening in which the open end 76a on the enclosed space 73 side is smaller than the open end 76b on an opposite side to the enclosed space 73. A part of the plasma light emission window 10B is positioned inside the light passage opening 75. In the light-emitting sealed body 1D, an end surface of the window member 13 of the plasma light emission window 10B on the enclosed space 73 side is positioned between the open end 75a of the light passage opening 75 and the open end 75b of the light passage opening 75. A part of the plasma light emission window 10C is positioned inside the light passage opening 76. In the light-emitting sealed body 1D, an end surface of the window member 15 of the plasma light emission window 10C on the enclosed space 73 side is positioned between the open end 76a of the light passage opening 76 and the open end 76b of the light passage opening 76.
As described above, in the light-emitting sealed body 1D, a part of the plasma light emission window 10B is positioned inside the light passage opening 75. As a result, the occurrence of the convection in the gas G in the enclosed space 73 can be further suppressed as compared with a case where the entire plasma light emission window 10B is positioned outside the light passage opening 75. In the light-emitting sealed body 1D, a part of the plasma light emission window 10C is positioned inside the light passage opening 76. As a result, it is possible to further suppress the occurrence of the convection in the gas G in the enclosed space 73 as compared with a case where the entire plasma light emission window 10C is positioned outside the light passage opening 76.

[Fifth Embodiment]

As illustrated in FIGS. 13, 14, and 15, a light-emitting sealed body 1E of a fifth embodiment is mainly different from the light-emitting sealed body 1C of the third embodiment in that a first enclosing portion 71 of the enclosure 7 is provided in the first holder 5 and a second enclosing portion 72 of the enclosure 7 is provided in the second holder 6. Hereinafter, the light-emitting sealed body 1E of the fifth embodiment will be described focusing on differences from the light-emitting sealed body 1C of the third embodiment.
The first holder 5 is an insulating member extending along the Y-axis direction, and holds the first electrode 3. The first holder 5 is made of an insulating material having high temperature resistance, such as ceramic. The first holder 5 includes a main body 51 and a tubular portion 52. A part of the main body 51 is positioned inside the housing 2, and the rest of the main body 51 is positioned outside the housing 2. The tubular portion 52 is provided in a portion of the main body 51 positioned outside the housing 2. The tubular portion 52 is positioned on an opposite side to the plasma region R with respect to the main body 51. A through-hole 51a penetrating the main body 51 along the Y-axis direction is formed in the main body 51. The through-hole 51a is opened to an inside of the tubular portion 52. The intermediate portion 32 of the first electrode 3 is disposed in the through-hole 51a. The side surface of the intermediate portion 32 is airtightly joined to the inner surface of the through-hole 51a by a joining material such as a metal brazing material. The proximal end 33 of the first electrode 3 is disposed inside the tubular portion 52.
The second electrode 4 extends from the outside of the housing 2 into the enclosed space 73 defined by the enclosure 7 via the electrode opening 27 of the housing 2 and the electrode opening 79 of the enclosure 7. In the light-emitting sealed body 1E, the second electrode 4 is a rod-shaped member extending in the Y-axis direction. A material of the second electrode 4 is, for example, a metal material having a high melting point such as tungsten. The distal end 41 of the second electrode 4 faces the plasma region R in the housing 2. In the light-emitting sealed body 1E, the distal end 41 of the second electrode 4 faces the plasma region R in the enclosed space 73 and is enclosed by the enclosure 7.
The light-emitting sealed body 1E includes the second holder 6. The second holder 6 is an insulating member extending along the Y-axis direction, and holds the second electrode 4. A material of the second holder 6 is an insulating material having high temperature resistance, and is, for example, ceramic. The second holder 6 includes a main body 61 and a tubular portion 62. A part of the main body 61 is positioned inside the housing 2, and the rest of the main body 61 is positioned outside the housing 2. The tubular portion 62 is provided in a portion of the main body 61 positioned outside the housing 2. The tubular portion 62 is positioned on an opposite side to the plasma region R with respect to the main body 61. A through-hole 61a penetrating the main body 61 along the Y-axis direction is formed in the main body 61. The through-hole 61a is opened to an inside of the tubular portion 62. An intermediate portion 42 of the second electrode 4 is disposed in the through-hole 61a. A side surface of the intermediate portion 42 is airtightly joined to an inner surface of the through-hole 61a by a joining material such as a metal brazing material. The proximal end 43 of the second electrode 4 is disposed inside the tubular portion 62.
The second holder 6 is fixed to the housing 2. In the light-emitting sealed body 1E, the second holder 6 is fixed to the housing 2 via the tubular connection member 9B. The connection member 9B includes a tubular portion 91B and an inward flange 92B. The inward flange 92B is provided at an end of the tubular portion 91B on an opposite side to the housing 2. A material of the connection member 9B is, for example, a metal material such as Kovar. The inward flange 92B is airtightly joined to an outward flange 63 provided in the main body 61 of the second holder 6 by a joining material such as a metal brazing material. An end of the tubular portion 91B on the housing 2 side is airtightly joined to the housing 2 by, for example, laser welding.
In the enclosure 7, the enclosed space 73, three light passage openings 74, 76, and 77, and two electrode openings 78 and 79 are formed. The enclosed space 73 includes the plasma region R. The light passage opening 74 is opened to one side in the Z-axis direction from the enclosed space 73. The light passage opening 77 is opened to the other side in the Z-axis direction from the enclosed space 73. The light passage opening 76 is opened to one side in the X-axis direction from the enclosed space 73. The electrode opening 78 is opened to one side in the Y-axis direction from the enclosed space 73. The electrode opening 79 is opened to the other side in the Y-axis direction from the enclosed space 73. A material of the enclosure 7 is an insulating material having high temperature resistance, and is, for example, ceramic. In particular, in a case where a white ceramic is used, the amount of light extracted from the plasma light emission window 10C can be further increased by reflecting the plasma light L2.
The enclosure 7 has a first enclosing portion 71 and a second enclosing portion 72. The first enclosing portion 71 defines most of the enclosed space 73, the three light passage openings 74, 76, and 77, and the electrode opening 78. The second enclosing portion 72 defines the electrode opening 79 and a part of the enclosed space 73 on the electrode opening 79 side. The first enclosing portion 71 is formed integrally with the first holder 5 in a state where the electrode opening 78 communicates with the through-hole 51a of the first holder 5. That is, the first enclosing portion 71 is provided in the first holder 5. The first enclosing portion 71 is formed integrally with the second holder 6 in a state where the electrode opening 79 communicates with the through-hole 61a of the second holder 6. That is, the second enclosing portion 72 is provided in the second holder 6.
As described above, in the light-emitting sealed body 1E, the first enclosing portion 71 of the enclosure 7 is provided in the insulating first holder 5 that holds the first electrode 3, and the second enclosing portion 72 of the enclosure 7 is provided in the insulating second holder 6 that holds the second electrode 4. As a result, the enclosure 7 can be formed by using the first holder 5 that holds the first electrode 3 and the second holder 6 that holds the second electrode 4.

[Modifications]

The present disclosure is not limited to the above embodiments. In the light-emitting sealed body 1A of the first embodiment, the second enclosing member 7B is a plate-shaped member, but the second enclosing member 7B may define the light passage opening 75. As an example, the second enclosing member 7B may be a substantially cubic member. In the light-emitting sealed body 1A of the first embodiment, the second enclosing member 7C is a plate-shaped member, but the second enclosing member 7C may define the light passage opening 76. As an example, the second enclosing member 7C may be a substantially cubic member.
In the light-emitting sealed body 1A of the first embodiment, the light-emitting sealed body 1B of the second embodiment, and the light-emitting sealed body 1D of the fourth embodiment, in the enclosure 7, at least one opening of the three light passage openings 74, 75, and 76 may be narrowed with respect to the enclosed space 73. In the light-emitting sealed body 1C of the third embodiment and the light-emitting sealed body 1E of the fifth embodiment, at least one of the two light passage openings 74 and 76 may be narrowed with respect to the enclosed space 73 in the enclosure 7. In this case, the occurrence of the convection in the gas G can also be reliably suppressed.
In the light-emitting sealed body 1E of the fifth embodiment, the first enclosing portion 71 of the enclosure 7 is provided in the insulating first holder 5 that holds the first electrode 3, but the entire enclosure 7 may be provided in the insulating first holder 5 that holds the first electrode 3.
The light-emitting sealed body 1A of the first embodiment, the light-emitting sealed body 1B of the second embodiment, the light-emitting sealed body 1C of the third embodiment, the light-emitting sealed body 1D of the fourth embodiment, and the light-emitting sealed body 1E of the fifth embodiment may not include the first electrode 3 and the second electrode 4. In this case, the plasma can also be generated by irradiating the gas G with the laser beam L1.
In the light-emitting sealed body 1B of the second embodiment, the two light passage openings 74 and 76 are opened in the region S1, but at least one of the two light passage openings 74 and 76 may be opened in the region S1.
In the light-emitting sealed body 1D of the fourth embodiment, a part of the plasma light emission window 10B is positioned inside the light passage opening 75, and a part of the plasma light emission window 10C is positioned inside the light passage opening 76. However, a part of the laser beam incidence window 10A may be positioned inside the light passage opening 74.

Reference Signs List

1A, 1B, 1C, 1D, 1E light-emitting sealed body
2 housing
7 enclosure
7A first enclosing member
7a, 7b inner surface
7B, 7C second enclosing member
10A laser beam incidence window (first window)
10B, 10C plasma light emission window (second window)
73 enclosed space
74a, 74b, 75a, 75b, 76a, 76b, 77a, 77b open end
74 light passage opening (first opening)
75, 76 light passage opening (second opening)
G gas
L1 laser beam (first light)
L2 plasma light (second light)
R plasma region
S1, S2 region.

Claims

A light-emitting sealed body comprising:
a housing that houses a gas for generating plasma, the housing including a first window configured to cause first light for maintaining the plasma in a plasma region where the plasma is generated to be incident on the plasma region, and a second window configured to emit second light emitted from the plasma from the plasma region; and

an enclosure defining an enclosed space including the plasma region in the housing and having a first opening corresponding to the first window and a second opening corresponding to the second window,

wherein the first window is positioned on an opposite side to the enclosed space with respect to an open end of the first opening on the enclosed space side,

the second window is positioned on an opposite side to the enclosed space with respect to an open end of the second opening on the enclosed space side, and

at least one of the first opening and the second opening is narrowed with respect to the enclosed space.
The light-emitting sealed body according to claim 1, wherein the enclosure is made of an insulating material.
The light-emitting sealed body according to claim 1 or 2, wherein the second opening is a tapered opening in which the open end of the second opening on the enclosed space side is smaller than an open end of the second opening on an opposite side to the enclosed space.
The light-emitting sealed body according to any one of claims 1 to 3,
wherein the enclosure includes a first enclosing member and a second enclosing member that are formed separately from each other,

the first enclosing member defines the first opening, and

the second enclosing member defines the second opening.
The light-emitting sealed body according to any one of claims 1 to 4,
wherein an inner surface of the enclosure includes a region having a smooth concave surface shape, and

at least one of the first opening and the second opening is opened in the region.
The light-emitting sealed body according to any one of claims 1 to 5, wherein a part of the second window is positioned inside the second opening.
The light-emitting sealed body according to any one of claims 1 to 6, wherein a region of an inner surface of the enclosure facing the first window with the plasma region interposed therebetween is a region having a smooth concave surface shape.