Patent Description:
A laser excitation light source is known as a light source in which plasma generated in a discharge gas is maintained by the irradiation of laser light and light from the plasma is output as output light. A laser excitation light source described in Patent Literature <NUM> includes a first container storing a discharge gas and a second container storing the first container. The second container is provided with a light transmission window through which laser light is transmitted and a light transmission window through which output light is transmitted.

In the above-described laser excitation light source, light loss is generated when the laser light and the output light are transmitted through the light transmission window and the first container. For that reason, there is room for improvement from the viewpoint of high efficiency and high output. <CIT> relates to a plasma based photon source comprising a first container for containing a gaseous medium in which a plasma is generated following excitation by a driving radiation, and a second container enclosing the first container. The radiation produced plasma-based photon source apparatus is operable to emit output radiation comprising a plurality of component wavelengths, the radiation further comprising an ultraviolet component and the second container is hermetically sealed and operable to substantially remove the ultraviolet component from the output radiation.

An object of an aspect of the present disclosure is to provide a light emitting sealed body and a light source device capable of achieving high efficiency and high output.

A light emitting sealed body according to the present invention is defined in claim <NUM>.

In the above-described light emitting sealed body, the first electrode and the second electrode are provided so as to face each other with the intersection between the first optical axis and the second optical axis interposed therebetween. Accordingly, plasma can be generated between the first electrode and the second electrode by applying a voltage between the first electrode and the second electrode. The housing is formed of the light shielding material that does not allow the first light and the second light to be transmitted therethrough. The internal space is defined by the housing, the first window portion, and the second window portion and the internal space is filled with the discharge gas. Accordingly, since the first light and the second light are not transmitted through a member other than the first window portion and the second window portion, light loss can be reduced. As a result, high efficiency and high output can be achieved.

The first window portion may include a first window member that allows the first light to be transmitted therethrough and the second window portion may include a second window member that allows the second light to be transmitted therethrough. In this case, it is possible to provide the window member in response to desirable properties for the first window portion and the second window portion.

The first window member and the second window member may be formed of the same material or different materials. In this case, an optimal material can be selected in response to a desired wavelength range.

Each of the first window member and the second window member may be formed in a flat plate shape. In this case, astigmatism can be suppressed.

Each of the first window member and the second window member may be formed of a material including at least one of diamond, sapphire, quartz, Kovar glass, and magnesium fluoride. In this case, for example, light having a long wavelength in the infrared region can be transmitted through the first window member and the second window member.

The first window portion may further include a first frame member hermetically fixed to the housing and the second window portion may further include a second frame member hermetically fixed to the housing. Then, the first window member may be hermetically joined to the first frame member by a first joining material and the second window member may be hermetically joined to the second frame member by a second joining material. In this case, the first window member can be satisfactorily joined to the first frame member and the second window member can be satisfactorily joined to the second frame member.

Each of the first joining material and the second joining material may be a metal brazing material and be more desirably a titanium-doped silver brazing material. In this case, the light emitting sealed body of which a temperature of an internal space is hot due to plasma can be reliably maintained in a hermetic state.

The housing is formed of a metal material. In this case, the enclosing pressure of the discharge gas can be further increased. Further, since the housing can be formed by machining, manufacturing tolerance can be reduced and manufacturing accuracy can be improved. The housing may be formed of an insulating material. In this case, components held by the housing can be easily electrically separated from each other.

The first electrode is fixed to the housing through an insulation member and is electrically separated from the housing. In this case, a voltage independent from the electric potential of the housing can be applied to the first electrode.

The first electrode may extend in a predetermined direction and include a first portion corresponding to a part of the first electrode in the predetermined direction and a second portion located closer to the second electrode than the first portion. Then, the insulation member may include a main body portion which holds the first portion and has a surface extending along a plane perpendicular to the predetermined direction and a cylindrical portion which extends from the surface of the main body portion and surrounds the second portion. In this case, the voltage withstanding capability of the second portion is improved by the cylindrical portion and a discharge between the first electrode and the housing can be suppressed.

The surface of the main body portion may be roughened. In this case, the voltage withstanding capability of the surface portion of the main body portion can be improved.

A depression may be formed in the surface of the main body portion so as to be separated from each of the first electrode and the cylindrical portion. In this case, the generation of the unexpected discharge can be effectively suppressed.

A depression may be formed in the surface of the main body portion so as to contact the first electrode and to be separated from the cylindrical portion. In this case, the generation of the unexpected discharge can be effectively suppressed.

The first electrode may extend in a predetermined direction and the insulation member may include a covering portion which surrounds a part of the first electrode in the predetermined direction. In this case, a discharge between the first electrode and the housing can be suppressed by the covering portion.

The covering portion may have a shape in which a thickness becomes thinner as it goes toward the second electrode. In this case, an electric field can be smoothly formed from the first electrode to the insulation member and a discharge caused by the disturbance of the electric field can be suppressed.

An outer peripheral surface of the covering portion may be roughened. In this case, the voltage withstanding capability of the covering portion is improved and a creeping discharge in the covering portion can be suppressed.

The second electrode is electrically connected to the housing. In this case, the second electrode can be set to a ground potential by the connection to the housing and a wiring for setting the ground potential can be omitted.

The first electrode may be fixed to the housing through a first insulation member and be electrically separated from the housing and the second electrode may be fixed to the housing through a second insulation member and be electrically separated from the housing. In this case, a voltage can be individually applied to the first electrode and the second electrode.

A light source device according to an aspect of the present disclosure includes the light emitting sealed body; and a light introduction unit which cause the first light to be incident to the first opening along the first optical axis. According to this light source device, high efficiency and high output can be achieved and the quality of the output light can be increased due to the above-described reasons.

According to an aspect of the present disclosure, it is possible to provide the light emitting sealed body and the light source device capable of achieving high efficiency and high output.

Hereinafter, an embodiment of the invention will be described in detail with reference to the drawings. Additionally, in the following description, the same or corresponding components will be denoted by the same reference symbols without redundant description.

As illustrated in <FIG>, a laser excitation light source (light source device) <NUM> includes a light emitting sealed body <NUM>, a laser light source <NUM>, a mirror <NUM>, an optical system <NUM>, and a casing (lamp house) <NUM>. The light emitting sealed body <NUM>, the laser light source <NUM>, the mirror <NUM>, and the optical system <NUM> are stored inside the casing <NUM>. A discharge gas G1 is enclosed in the light emitting sealed body <NUM>. The discharge gas G1 is, for example, a xenon gas. In the laser excitation light source <NUM>, plasma is generated in the discharge gas G1. First light L1 which is laser light for maintaining plasma is incident to the light emitting sealed body <NUM> and second light L2 which is light from plasma is emitted from the light emitting sealed body <NUM> as output light. The first light has a wavelength of, for example, about <NUM> to <NUM>. The second light L2 is, for example, light in the mid-infrared region and has a wavelength of about <NUM> to <NUM>. The light emitting sealed body <NUM> will be described in detail later.

The laser light source <NUM> is, for example, a laser diode and outputs the first light L1 which is laser light. The mirror <NUM> reflects the first light L1 from the laser light source <NUM> toward the optical system <NUM>. The optical system <NUM> includes one or plural lenses. The optical system <NUM> guides the first light L1 from the mirror <NUM> to the light emitting sealed body <NUM> while condensing the first light L1. The laser light source <NUM>, the mirror <NUM>, and the optical system <NUM> constitute a light introduction unit R which causes the first light L1 to be incident to a first opening <NUM> along a first optical axis A1. The first opening <NUM> and the first optical axis A1 will be described later.

The casing <NUM> includes a main body portion <NUM> and a lid member <NUM>. A storage space S1 is formed inside the main body portion <NUM> and the laser light source <NUM>, the mirror <NUM>, and the optical system <NUM> are arranged inside the storage space S1. A depression 61a is formed in the main body portion <NUM> and an opening portion of the depression 61a is closed by the lid member <NUM> so as to form a storage space S2. The light emitting sealed body <NUM> is disposed inside the storage space S2. The main body portion <NUM> includes a pair of wall portions <NUM> which define the depression 61a and each wall portion <NUM> is provided with an opening 611a through which the second light L2 emitted from the light emitting sealed body <NUM> passes. The second light L2 passes through the opening 611a and is emitted to the outside.

The main body portion <NUM> includes a wall portion <NUM> which divides the storage space S1 and the depression 61a and the storage space S1 and the storage space S2 are divided by the wall portion <NUM>. Further, an opening 612a is formed in the wall portion <NUM>. A part of the optical system <NUM> is disposed inside the opening 612a and the first light L1 passes through the opening 612a and is incident to the light emitting sealed body <NUM>.

A flow path <NUM> is formed inside the lid member <NUM>. A gas G2 flows in the flow path <NUM>. The gas G2 is, for example, an inert gas such as nitrogen. The flow path <NUM> is connected to the outside through an opening 63a and the gas G2 is supplied from an external gas supply device (not illustrated) to the flow path <NUM> through the opening 63a. The flow path <NUM> is connected to the storage space S2 of the main body portion <NUM> through an opening 63b and the gas G2 flows from the flow path <NUM> into the storage space S2 through the opening 63b.

The gas G2 passes between the wall portions <NUM> and <NUM> of the main body portion <NUM> and the light emitting sealed body <NUM> and/or between the lid member <NUM> and the light emitting sealed body <NUM> and is discharged from a ventilation hole 613a to the outside. The ventilation hole 613a is a through-hole which is formed in a wall portion <NUM> of the main body portion <NUM> so as to communicate with the storage space S2. The wall portion <NUM> includes a pair of tapered surfaces 613b which are respectively formed at the boundary portions of the pair of wall portions <NUM>. The pair of tapered surfaces 613b are inclined so as to be closer to each other as it goes toward the ventilation hole 613a. Each tapered surface 613b is connected to the ventilation hole 613a. The tapered surface 613b guides the gas G2 toward the ventilation hole 613a. A through-hole 612b is formed in the wall portion <NUM> of the main body portion <NUM> and a part of the gas G2 flowing from the flow path <NUM> to the storage space S2 passes through the through-hole 612b and flows into the storage space S1.

The light emitting sealed body <NUM> includes a housing <NUM>, a first window portion <NUM>, two second window portions <NUM>, a first electrode <NUM>, and a second electrode <NUM>.

The housing <NUM> is formed in a substantially box shape by a metal material and stores the discharge gas G1. More specifically, a sealed internal space S3 is formed inside the housing <NUM> and the internal space S3 is filled with the discharge gas G1. As an example of the metal material forming the housing <NUM>, stainless steel is exemplified. In this case, the housing <NUM> has a light shielding property with respect to the first light L1 and the second light L2. That is, the housing <NUM> is formed of a light shielding material which does not allow the first light L1 and the second light L2 to be transmitted therethrough.

The first opening <NUM> and two second openings <NUM> are formed in the housing <NUM>. The first light L1 is incident to the first opening <NUM> along the first optical axis A1. The first opening <NUM> is formed in a circular shape, for example, as viewed from a direction (hereinafter, referred to as a Z-axis direction) parallel to the first optical axis A1. In this example, the first optical axis A1 passes through the center of the first opening <NUM> as viewed from the Z-axis direction. The first opening <NUM> includes an inner portion 11a, a middle portion 11b, and an outer portion 11c. The inner portion 11a opens to the internal space S3. The outer portion 11c opens to the outside. The middle portion 11b is connected to the inner portion 11a and the outer portion 11c. Each of the inner portion 11a, the middle portion 11b, and the outer portion 11c has, for example, a cylindrical shape. The diameter (outer shape) of the middle portion 11b is larger than the diameter (outer shape) of the inner portion 11a and the diameter (outer shape) of the outer portion 11c is larger than the diameter (outer shape) of the middle portion 11b. A part of the optical system <NUM> is disposed in the outer portion 11c.

The second light L2 is emitted from each second opening <NUM> along a second optical axis A2. Each second opening <NUM> is formed in, for example, a circular shape as viewed from a direction (hereinafter, referred to as a Y-axis direction) parallel to the second optical axis A2. In this example, the second optical axis A2 passes through the center of the second opening <NUM> as viewed from the Y-axis direction. Each second opening <NUM> includes an inner portion 12a, a middle portion 12b, and an outer portion 12c. The inner portion 12a opens to the internal space S3. The outer portion 12c opens to the outside. The middle portion 12b is connected to the inner portion 12a and the outer portion 12c. Each of the inner portion 12a, the middle portion 12b, and the outer portion 12c has, for example, a cylindrical shape. The diameter (outer shape) of the middle portion 12b is larger than the diameter (outer shape) of the inner portion 12a and the diameter (outer shape) of the outer portion 12c is larger than the diameter (outer shape) of the middle portion 12b.

The first optical axis A1 intersects the second optical axis A2 inside the internal space S3. That is, the first opening <NUM> and the second opening <NUM> are disposed so that the first optical axis A1 and the second optical axis A2 intersect each other. An intersection C between the first optical axis A1 and the second optical axis A2 is located inside the internal space S3. In this example, the first optical axis A1 perpendicularly intersects the second optical axis A2, but the first optical axis A1 may intersect the second optical axis A2 at an angle other than a right angle. The first optical axis A1 is not parallel to the second optical axis A2. The first optical axis A1 does not pass through the second opening <NUM> and the second optical axis A2 does not pass through the first opening <NUM>.

The first window portion <NUM> hermetically seals the first opening <NUM>. The first window portion <NUM> includes a first window member <NUM> and a first frame member <NUM>. The first window member <NUM> is formed in, for example, a circular flat plate shape by a translucent material that allows the first light L1 to be transmitted therethrough. In this example, the first window member <NUM> is formed of sapphire and allows light having a wavelength of <NUM> or less to be transmitted therethrough.

The first frame member <NUM> is formed in, for example, a frame shape by Kovar metal. The first frame member <NUM> is formed in a substantially cylindrical shape as a whole. The first frame member <NUM> includes a first portion 22a having a cylindrical shape and a second portion 22b having a cylindrical shape and integrally formed with the first portion 22a. The outer shape of the second portion 22b is larger than the outer shape of the first portion 22a.

The first window member <NUM> is disposed inside the first portion 22a. Specifically, a boundary portion between the inner surface of the first portion 22a and the inner surface of the second portion 22b is provided with a circular ring-shaped protrusion portion 22c which protrudes inward and the first window member <NUM> is disposed inside the first portion 22a while contacting the protrusion portion 22c. In this state, a side surface 21a of the first window member <NUM> contacts the inner surface of the first portion 22a.

The side surface 21a of the first window member <NUM> is hermetically joined to the inner surface of the first portion 22a over the entire circumference by a joining material (first joining material) <NUM>. Accordingly, a gap between the first window member <NUM> and the first frame member <NUM> is hermetically sealed. The joining material <NUM> is, for example, a metal brazing material and is, more specifically, a titanium-doped silver brazing material. The titanium-doped silver brazing material is a brazing material composed of, for example, <NUM>% of silver, <NUM>% of copper, and <NUM>% of Ti and is, for example, TB-608T manufactured by Tokyo Braze Co.

An outer surface of the second portion 22b is provided with a circular ring-shaped flange portion 22d which protrudes outward. The first frame member <NUM> is fixed to the housing <NUM> while the flange portion 22d is disposed inside the middle portion 11b of the first opening <NUM>. In this state, a part of the first portion 22a of the first frame member <NUM> protrudes from the first opening <NUM>. The first window member <NUM> is disposed so as to face the intersection C between the first optical axis A1 and the second optical axis A2. In this example, the light incident surface and the light emitting surface of the first window member <NUM> are flat surfaces which extend so as to be perpendicular to the Z-axis direction.

The first frame member <NUM> is hermetically fixed to the housing by laser welding. More specifically, a contact portion between the flange portion 22d and the inner surface of the middle portion 11b of the first opening <NUM> is irradiated with laser from the outside to be welded over the entire circumference, so that the first frame member <NUM> is hermetically joined to the housing <NUM>. In <FIG> and <FIG>, a welded part is denoted by the sign W. Accordingly, a part between the first frame member <NUM> and the housing <NUM> is hermetically sealed. In this way, the first window member <NUM> is hermetically joined to the first frame member <NUM> by the joining material <NUM> and is hermetically fixed to the housing <NUM> via the first frame member <NUM>. Since the first frame member <NUM> is interposed between the first window member <NUM> and the housing <NUM>, problems caused by a difference in thermal expansion rate between the first window member <NUM> and the housing <NUM> can be suppressed.

Each second window portion <NUM> hermetically seals the second opening <NUM>. Each second window portion <NUM> includes a second window member <NUM> and a second frame member <NUM>. The second window member <NUM> is formed in, for example, a circular flat plate shape by a translucent material that allows the second light L2 to be transmitted therethrough. In this example, the second window member <NUM> is formed of diamond and allows light having a wavelength of <NUM> or less to be transmitted therethrough.

The second frame member <NUM> is formed in, for example, a frame shape by Kovar metal. The second frame member <NUM> is formed in a substantially cylindrical shape as a whole. The second frame member <NUM> includes a first portion 32a having a cylindrical shape and a second portion 32b having a cylindrical shape and integrally formed with the first portion 32a. The outer shape of the second portion 32b is larger than the outer shape of the first portion 32a.

The second window member <NUM> is disposed inside the first portion 32a. Specifically, the first portion 32a includes an arrangement portion 32c therein and the second window member <NUM> is disposed inside the arrangement portion 32c. In this state, a part on the side opposite to the intersection C in the side surface 31a of the second window member <NUM> contacts the inner surface of the first portion 32a. A space inside the second frame member <NUM> further includes a middle portion 32d connected to the arrangement portion 32c and an outer portion 32e connected to the middle portion 32d. The middle portion 32d has a truncated cone shape in which a diameter (outer shape) increases when going outward. The outer portion 32e is formed in a cylindrical shape having a diameter (outer shape) larger than the middle portion 32d.

The side surface 31a of the second window member <NUM> is hermetically joined to the inner surface of the first portion 32a over the entire circumference by a joining material (second joining material) <NUM>. Accordingly, a part between the second window member <NUM> and the second frame member <NUM> is hermetically sealed. The joining material <NUM> is, for example, a metal brazing material and is, more specifically, a titanium-doped silver brazing material.

An outer surface of the second portion 32b is provided with a circular ring-shaped flange portion 32f which protrudes outward. The second frame member <NUM> is fixed to the housing <NUM> while the flange portion 32f is disposed inside the middle portion 12b of the second opening <NUM>. In this state, a part of the first portion 32a of the second frame member <NUM> protrudes from the second opening <NUM>. The second window member <NUM> is disposed so as to face the intersection C between the first optical axis A1 and the second optical axis A2. In this example, the light incident surface and the light emitting surface of the second window member <NUM> are flat surfaces which extend so as to be perpendicular to the Y-axis direction.

The second frame member <NUM> is hermetically fixed to the housing by laser welding. More specifically, a contact portion between the flange portion 32f and the inner surface of the middle portion 12b of the second opening <NUM> is irradiated with laser from the outside to be welded over the entire circumference, so that the second frame member <NUM> is hermetically joined to the housing <NUM>. Accordingly, a part between the second frame member <NUM> and the housing <NUM> is hermetically sealed. In this way, the second window member <NUM> is hermetically joined to the second frame member <NUM> by the joining material <NUM> and is hermetically fixed to the housing <NUM> through the second frame member <NUM>. Since the second frame member <NUM> is interposed between the second window member <NUM> and the housing <NUM>, problems caused by a difference in thermal expansion rate between the second window member <NUM> and the housing <NUM> can be suppressed.

The first electrode <NUM> extends along an X-axis direction (predetermined direction) which is perpendicular to both the Y-axis direction and the Z-axis direction. The first electrode <NUM> faces the second electrode <NUM> with the intersection C between the first optical axis A1 and the second optical axis A2 interposed therebetween. A distance between the intersection C and a front end of the first electrode <NUM> in the X-axis direction is the same as a distance between the intersection C and a front end of the second electrode <NUM>. The first electrode <NUM> is formed of, for example, a metal material such as tungsten. The first electrode <NUM> is fixed to the housing <NUM> via a first insulation member <NUM> at the base end side thereof and is electrically separated from the housing <NUM>. The first electrode <NUM> is formed in a substantially rod shape as a whole. The first electrode <NUM> includes a first support portion (first portion) <NUM> formed at a base end side and a first discharge portion (second portion) <NUM> located closer to the front end of the second electrode <NUM> than the first support portion <NUM>. The first discharge portion <NUM> has a diameter smaller than that of the first support portion <NUM> and has a pointed shape. A boundary portion between the first support portion <NUM> and the first discharge portion <NUM> is provided with a tapered portion <NUM>. The tapered portion <NUM> has a surface which is inclined so that a diameter increases as it goes toward the first support portion <NUM>. The tapered portion <NUM> is disposed at a positional relationship that forms a recess with respect to a surface 71a of a main body portion <NUM> to be described later. With such an arrangement of the tapered portion <NUM>, electrons E generated in a triple junction P to be described later can be caught in the recess. The first support portion <NUM> is a middle portion (a part) of the first electrode <NUM> in the X-axis direction. An end portion 41a at a base end side opposite to the first discharge portion <NUM> in the first support portion <NUM> is formed so as to be thicker than a portion other than the end portion 41a. The first discharge portion <NUM> is formed in a rod shape and is disposed inside the housing <NUM> (that is, inside the internal space S3).

The first insulation member <NUM> includes the main body portion <NUM> and a cylindrical portion <NUM>. The first insulation member <NUM> is formed of, for example, an insulating material such as alumina (aluminum oxide) or ceramic. The main body portion <NUM> is formed in, for example, a columnar shape and holds the first support portion <NUM> of the first electrode <NUM>. The main body portion <NUM> includes the surface 71a perpendicular to the X-axis direction. The surface 71a is a surface exposed to the internal space S3. The surface 71a is provided with an insertion hole 71b which penetrates the main body portion <NUM> in the X-axis direction and the first support portion <NUM> is disposed inside the insertion hole 71b and is fixed. The cylindrical portion <NUM> is formed in a cylindrical shape so as to extend along the X-axis direction from the surface 71a of the main body portion <NUM> and surrounds a part at the side (the base end side) of the first support portion <NUM> in the first discharge portion <NUM>.

The end portion 41a of the first support portion <NUM> is hermetically joined to the inner surface of the insertion hole 71b over the entire circumference by a joining material <NUM>. Accordingly, a gap between the first electrode <NUM> and the first insulation member <NUM> is hermetically sealed. The joining material <NUM> is, for example, a metal brazing material and is, more specifically, a titanium-doped silver brazing material.

The surface 71a of the main body portion <NUM> is roughened. In this embodiment, the surface 71a is roughened by forming a depression <NUM> in the surface 71a. The depression <NUM> extends in a circular ring shape so as to surround the first discharge portion <NUM> as viewed from the X-axis direction. The depression <NUM> is disposed so as to be separated from each of the first electrode <NUM> and the cylindrical portion <NUM>. The shape of the depression <NUM> in a cross-section parallel to the X-axis direction is, for example, a rectangular shape.

The first insulation member <NUM> is hermetically fixed to the housing <NUM> via a connection member <NUM>. An outer surface of the main body portion <NUM> of the first insulation member <NUM> is provided with a circular ring-shaped flange portion <NUM> which protrudes outward. The connection member <NUM> is formed of a metal material such as stainless steel. The connection member <NUM> includes a first portion <NUM> having a cylindrical shape and a second portion <NUM> having a ring-shaped flat plate shape and extending from a first end portion 81a of the first portion <NUM> inward in the radial direction. A front end of the second portion <NUM> contacts the outer surface of the main body portion <NUM>. The flange portion <NUM> contacts the first portion <NUM> and the second portion <NUM>.

The second portion <NUM> of the connection member <NUM> is hermetically joined to the outer surface of the main body portion <NUM> of the first insulation member <NUM> over the entire circumference by a joining material <NUM>. Accordingly, a part between the connection member <NUM> and the first insulation member <NUM> is hermetically sealed. The joining material <NUM> is, for example, a metal brazing material and is, more specifically, a titanium-doped silver brazing material.

The connection member <NUM> is hermetically fixed to the housing <NUM> by laser welding. More specifically, a third opening <NUM> is formed in the housing <NUM>. The cylindrical portion <NUM> of the first insulation member <NUM> is disposed inside the third opening <NUM> while being apart from the third opening <NUM>. The connection member <NUM> is disposed so that a second end portion 81b of the first portion <NUM> contacts an opening edge of the third opening <NUM>. A contact portion between the first portion <NUM> and the opening edge of the third opening <NUM> is irradiated with laser from the outside to be welded over the entire circumference, so that the connection member <NUM> is hermetically joined to the housing <NUM>. Accordingly, a part between the connection member <NUM> and the housing <NUM> is hermetically sealed. In this way, the first insulation member <NUM> is hermetically joined to the connection member <NUM> and is hermetically fixed to the housing <NUM> via the connection member <NUM>. In this state, the first electrode <NUM> extends so as to penetrate the third opening <NUM>. The third opening <NUM> is hermetically sealed by the first electrode <NUM>, the first insulation member <NUM>, and the connection member <NUM>. The connection member <NUM> can also be regarded as forming a part of the housing <NUM>.

The second electrode <NUM> extends along the X-axis direction. The front end of the second electrode <NUM> faces the first electrode <NUM> with the intersection C between the first optical axis A1 and the second optical axis A2 interposed therebetween. The second electrode <NUM> is formed of, for example, a metal material such as tungsten. The second electrode <NUM> is electrically connected to the housing <NUM>. The second electrode <NUM> is formed in a substantially rod shape having diameter larger than that of the first electrode <NUM> as a whole. The second electrode <NUM> includes a second support portion <NUM> formed at a base end side and a second discharge portion <NUM> located closer to the front end of the first electrode <NUM> than the second support portion <NUM> and having a pointed shape. The second support portion <NUM> is a middle portion (a part) of the second electrode <NUM> in the X-axis direction. The second discharge portion <NUM> is formed in a rod shape and is disposed inside the housing <NUM> (that is, inside the internal space S3).

A fourth opening <NUM> is formed in the housing <NUM>. The second support portion <NUM> of the second electrode <NUM> is disposed inside the fourth opening <NUM> so that an outer surface of the second support portion <NUM> contacts the inner surface of the fourth opening <NUM>. The second support portion <NUM> is hermetically joined to the inner surface of the fourth opening <NUM> over the entire circumference by a joining material <NUM>. Accordingly, a part between the second electrode <NUM> and the housing <NUM> is hermetically sealed. The joining material <NUM> is, for example, a metal brazing material and is, more specifically, a titanium-doped silver brazing material.

The housing <NUM> is provided with an enclosing hole <NUM> for enclosing the discharge gas G1 in the internal space S3. An enclosing tube <NUM> is connected to the enclosing hole <NUM>. The enclosing tube <NUM> is formed of, for example, a metal material such as copper. An end portion 16a opposite to the enclosing hole <NUM> in the enclosing tube <NUM> is sealed. A protection member <NUM> is attached to the enclosing tube <NUM> so as to cover the sealed end portion 16a. The protection member <NUM> is formed of, for example, a resin material such as rubber.

An outer surface of the enclosing tube <NUM> is joined to the inner surface of the enclosing hole <NUM> over the entire circumference by a joining material <NUM>. Accordingly, a part between the enclosing tube <NUM> and the housing <NUM> is hermetically sealed. The joining material <NUM> is, for example, a metal brazing material and is, more specifically, a titanium-doped silver brazing material. When enclosing the discharge gas G1, for example, the discharge gas G1 is introduced into the internal space S3 through the enclosing tube <NUM> and the end portion 16a of the enclosing tube <NUM> is sealed by pressing and cutting (cutting out) the enclosing tube <NUM> while crushing the enclosing tube <NUM>. Then, the protection member <NUM> is attached to the enclosing tube <NUM>. Such a direct enclosing method is advantageous in the following points compared to a trap method using liquid nitrogen. That is, in the trap method, there is concern that the window member may be distorted when liquid nitrogen is placed in the light emitting sealed body. In the direct enclosing method, such a situation can be suppressed. Further, a variation in enclosing pressure may be generated in the trap method, but such a variation can be suppressed in the direct enclosing method. The trap method may be used when enclosing the discharge gas in a glass bulb.

In the light emitting sealed body <NUM>, the internal space S3 is defined by the housing <NUM>, the first window portion <NUM>, and the second window portion <NUM>. In the light emitting sealed body <NUM>, the internal space S3 is also defined by the first electrode <NUM>, the second electrode <NUM>, the first insulation member <NUM>, the connection member <NUM>, and the enclosing tube <NUM>. The entire internal space S3 is filled with the discharge gas G1. That is, the internal space S3 is filled with the discharge gas G1. The discharge gas G1 contacts the first window member <NUM>, the first frame member <NUM>, the second window member <NUM>, and the second frame member <NUM>. The enclosing pressure (the maximal enclosing pressure) of the discharge gas G1 is, for example, about <NUM> MPa (<NUM> atm). The light emitting sealed body <NUM> can withstand an internal pressure of <NUM> MPa or more.

In the laser excitation light source <NUM>, a negative voltage pulse is applied to the first electrode <NUM> by a voltage application circuit (a voltage application unit) (not illustrated) disposed inside the casing 6using the second electrode <NUM> as a ground potential. Accordingly, electrons are discharged from the first electrode <NUM> toward the second electrode <NUM>. As a result, an arc discharge is generated and plasma is generated in a gap (intersection C) between the first electrode <NUM> and the second electrode <NUM>. This plasma is irradiated with the first light L1 from the light introduction unit R through the first window member <NUM>. Accordingly, the generated plasma is maintained. The second light L2 which is the light from the plasma is emitted as the output light to the outside through the second window member <NUM>. In the laser excitation light source <NUM>, the second light L2 is emitted from two second window members <NUM> toward both sides of the Y-axis direction. A positive voltage pulse which is a trigger voltage for generating plasma may be applied to the first electrode <NUM>. In this case, electrons are discharged from the second electrode <NUM> toward the first electrode <NUM>.

In the light emitting sealed body <NUM>, the first electrode <NUM> and the second electrode <NUM> are provided so as to face each other with the intersection C between the first optical axis A1 and the second optical axis A2 interposed therebetween. Accordingly, plasma can be generated between the first electrode <NUM> and the second electrode <NUM> by applying a voltage between the first electrode <NUM> and the second electrode50. The housing <NUM> is formed of a light shielding material which does not allow the first light L1 and the second light L2 to be transmitted therethrough. The internal space S3 is defined by the housing <NUM>, the first window portion <NUM>, and the second window portion <NUM> and the internal space S3 is filled with the discharge gas G1. Accordingly, since a material having a relatively high strength such as a metal material can be selected as the light shielding material, the enclosing pressure of the discharge gas G1 can be increased. As a result, high efficiency and high output can be achieved. Further, since the first light L1 and the second light L2 are not transmitted through a member other than the first window portion <NUM> and the second window portion <NUM>, the loss of light can be reduced. Also by this, high efficiency and high output can be achieved. Further, the first opening <NUM> and the second opening <NUM> are disposed so that the first optical axis A1 and the second optical axis A2 intersect each other. Accordingly, since it is possible to suppress the first light L1 from being emitted from the second opening <NUM> to be mixed with the second light L2, the quality of the output light can be increased. Thus, according to the light emitting sealed body <NUM>, high efficiency and high output can be achieved and the quality of the output light can be increased.

The first window member <NUM> is formed of sapphire and the second window member <NUM> is formed of diamond. Accordingly, for example, light having a long wavelength in the infrared region can be transmitted through the first window member <NUM> and the second window member <NUM>.

Each of the first window member <NUM> and the second window member <NUM> is formed in a flat plate shape. Accordingly, astigmatism can be suppressed. For example, in a light emitting sealed body in which a pair of electrodes are disposed inside a glass housing having a curved surface, astigmatism is generated when laser light and output light are transmitted through the curved surface, but in the light emitting sealed body <NUM>, generation of such astigmatism can be suppressed.

The first window member <NUM> is hermetically joined to the first frame member <NUM> by a titanium-doped silver brazing material and the second window member <NUM> is hermetically joined to the second frame member <NUM> by a titanium-doped silver brazing material. Accordingly, the first window member <NUM> can be satisfactorily joined to the first frame member <NUM> and the second window member <NUM> can be satisfactorily joined to the second frame member <NUM>. More specifically, the present inventors have found that a silver brazing material is repelled and unfamiliar in a configuration in which a window member formed of diamond is joined to a frame member formed of Kovar metal by a silver brazing material not doped with titanium. The present inventors have found that a silver brazing material becomes familiar when the window member is joined to the frame member using a titanium-doped silver brazing material and the window member can be satisfactorily joined to the frame member.

The housing <NUM> is formed of a metal material. Accordingly, the enclosing pressure of the discharge gas G1 can be further increased. Further, since the housing <NUM> can be formed by machining, manufacturing tolerance can be reduced and manufacturing accuracy can be improved.

The second electrode <NUM> is electrically connected to the housing <NUM>. Accordingly, the second electrode <NUM> can be set to a ground potential by the connection to the housing <NUM> and the wiring for setting the ground potential can be omitted.

The first electrode <NUM> is fixed to the housing <NUM> through the first insulation member <NUM> and is electrically separated from the housing <NUM>. Accordingly, a voltage independent from the electric potential (ground potential) of the housing can be applied to the first electrode <NUM>.

The first insulation member <NUM> includes the main body portion <NUM> which holds the first support portion <NUM> of the first electrode <NUM> and the depression <NUM> is formed in the surface 71a of the main body portion <NUM>. As the enclosing pressure of the discharge gas G1 becomes higher, a discharge starting voltage becomes higher according to Paschen's law. For that reason, the voltage applied between the first electrode <NUM> and the second electrode <NUM> needs to be large. On the other hand, there is concern that an unexpected discharge may be generated inside the housing <NUM> due to electrons generated in the vicinity of the triple junction in which the discharge gas G1, the first insulation member <NUM>, and the first electrode <NUM> are in contact with each other when the applied voltage is large. Regarding this point, in the light emitting sealed body <NUM>, the depression <NUM> is formed in the surface 71a of the main body portion <NUM> of the first insulation member <NUM>. Accordingly, it is possible to suppress that electrons generated in the triple junction move along the surface 71a and reach the cylindrical portion <NUM> and to suppress the generation of the unexpected discharge.

This point will be described further with reference to <FIG>. In <FIG>, an electric field distribution generated in the configurations of <FIG> is illustrated by equipotential lines. Among the equipotential lines, the equipotential lines which are closer to the first electrode <NUM> have lower potentials. In <FIG>, only the lower side of the drawing is illustrated, but the same electric field distribution is also generated at the upper side. These are also the same for <FIG> and <FIG> to be described later.

In a first modified example illustrated in <FIG>, the depression <NUM> is not formed and the surface 71a of the main body portion <NUM> is flat. Electrons E are apt to be generated in the vicinity of the triple junction P in which the discharge gas G1, the first insulation member <NUM>, and the first electrode <NUM> are in contact with each other. The electrons E hop and move on the surface of the first insulation member <NUM> due to the electric field generated as illustrated in <FIG> and positively charge the surface of the first insulation member <NUM>. The electrons are attracted to this positive charge and secondary electron multiplication may be generated. As a result, the secondary electrons that have acceleratedly increased in amount collide with molecules of the discharge gas G1 on the surface of the first insulation member <NUM> and release the molecules, so that a creeping discharge may be generated.

In contrast, as illustrated in <FIG>, in the light emitting sealed body <NUM>, the depression <NUM> is formed in the surface 71a of the main body portion <NUM> of the first insulation member <NUM>. Accordingly, the electrons E generated in the triple junction P can be captured by the depression <NUM>. As a result, it is possible to suppress that the electrons E move along the surface 71a and reach the cylindrical portion <NUM> and to suppress the generation of the above-described unexpected discharge. In the light emitting sealed body <NUM>, an electric field is generated as illustrated in <FIG>.

Further, in the light emitting sealed body <NUM>, the depression <NUM> is disposed so as to be separated from each of the first electrode <NUM> and the cylindrical portion <NUM>. Accordingly, it is possible to effectively suppress the generation of the unexpected discharge.

In a second modified example illustrated in <FIG>, the depression <NUM> is disposed so as to contact the first electrode <NUM> and to be separated from the cylindrical portion <NUM>. Also in the second modified example, similarly to the above-described embodiment, high efficiency and high output can be achieved and the quality of the output light can be increased. Further, the electrons E generated in the triple junction P can be captured by the depression <NUM> and the generation of the unexpected discharge can be effectively suppressed. In the second modified example, an electric field is generated as illustrated in <FIG>.

In a third modified example illustrated in <FIG>, the first insulation member <NUM> includes a covering portion <NUM> which surrounds a part of the base end side of the first electrode <NUM> in the X-axis direction. An inner peripheral surface 75b of the covering portion <NUM> surrounds a part of the front end side of the first support portion <NUM> and a part of the base end side of the first discharge portion <NUM>. A gap <NUM> which extends to the tapered portion <NUM> of the base end side of the first discharge portion <NUM> is formed between the inner peripheral surface 75b and the outer peripheral surface of the first electrode <NUM>. The covering portion <NUM> has a shape in which a thickness becomes thinner as it goes toward the second electrode <NUM> and an outer peripheral surface 75a of the covering portion <NUM> becomes a tapered surface. The outer peripheral surface 75a of the covering portion <NUM> is roughened. In the third modified example, the outer peripheral surface 75a is roughened by forming a plurality of grooves <NUM> extending around the first electrode <NUM> in the outer peripheral surface 75a. The plurality of grooves <NUM> are arranged side by side in the X-axis direction. Each groove <NUM> extends in a circular ring shape so as to surround the first electrode <NUM>. The shape of the groove <NUM> in a cross-section parallel to the X-axis direction is, for example, a semi-circular shape.

Also in the third modified example, similarly to the above-described embodiment, high efficiency and high output can be achieved and the quality of the output light can be increased. Further, electrons generated in the triple junction P are difficult to reach the outer peripheral surface 75a of the covering portion <NUM> due to the gap <NUM> and the movement of electrons along the outer peripheral surface 75a can be suppressed by the plurality of grooves <NUM>, so that the generation of the unexpected discharge can be suppressed. That is, in the third modified example, an electric field is generated as illustrated in <FIG>. Electrons easily move in the direction in which the equipotential lines are arranged (perpendicular to the electric field) and are difficult to move along the equipotential lines. Therefore, in the third modified example, electrons generated in the triple junction P are not easy to move along the outer peripheral surface 75a of the covering portion <NUM>.

In a fourth modified example illustrated in <FIG>, the second electrode <NUM> is fixed to the housing <NUM> via a second insulation member 7A and is electrically separated from the housing <NUM>. The second insulation member 7A is hermetically fixed to the housing <NUM> through a connection member 8A. The second insulation member 7A is configured and connected similarly to the first insulation member <NUM> and the connection member 8A is configured and connected similarly to the connection member <NUM>.

Also in the fourth modified example, similarly to the above-described embodiment, high efficiency and high output can be achieved and the quality of the output light can be increased. Further, since the second electrode <NUM> is electrically separated from the housing <NUM>, a voltage can be individually applied to the first electrode <NUM> and the second electrode <NUM>. For example, a positive voltage pulse may be applied to the second electrode <NUM> in accordance with a timing at which a negative voltage pulse is applied to the first electrode <NUM>. In this case, it is possible to reduce an absolute value of a peak voltage of each of the negative voltage pulse applied to the first electrode <NUM> and the positive voltage pulse applied to the second electrode <NUM> compared to a case in which the negative voltage pulse is applied only to the first electrode <NUM>. As a result, for example, noise caused when generating the negative voltage pulse and the positive voltage pulse can be reduced.

In a fifth modified example illustrated in <FIG>, a mirror <NUM> is disposed inside the housing <NUM>. The mirror <NUM> faces the first window member <NUM> with the intersection C between the first optical axis A1 and the second optical axis A2 interposed therebetween. In the fifth modified example, the first light L1 passing through plasma in the first light L1 irradiated on the plasma from the first window member <NUM> is returned to the plasma while being condensed by the mirror <NUM>. Also in the fifth modified example, similarly to the above-described embodiment, high efficiency and high output can be achieved and the quality of the output light can be increased. Further, since the first light L1 passing through the plasma can be returned to the plasma by the mirror <NUM>, higher efficiency and higher output can be achieved.

In a sixth modified example illustrated in <FIG>, each of the first window member <NUM> and the second window member <NUM> has a lens shape. Also in the sixth modified example, similarly to the above-described embodiment, high efficiency and high output can be achieved and the quality of the output light can be increased. Further, the first window member <NUM> and the second window member <NUM> can have a lens effect and a beam diameter can be decreased.

In a seventh modified example illustrated in <FIG>, an insulation member (a space limiting member) <NUM> is disposed inside the housing <NUM>. The insulation member <NUM> is formed in, for example, a block shape by an insulating material such as ceramic. The insulation member <NUM> is disposed so as to fill a region other than the optical paths of the first light L1 and the second light L2 in the internal space S3. As illustrated in <FIG>, the first light L1 is directed toward the intersection C while being condensed and the second light L2 is directed from the intersection C toward the outside while being widened. The insulation member <NUM> includes a first opening 93a to which the first light L1 is incident and two second openings 93b from which the second light L2 is emitted. Also in the seventh modified example, similarly to the above-described embodiment, high efficiency and high output can be achieved and the quality of the output light can be increased. Further, the generation of the leakage current inside the housing <NUM> can be suppressed. Further, since the internal space S3 is filled by the insulation member <NUM>, it is possible to suppress convection due to the discharge gas G1 in the internal space S3. As a result, it is possible to suppress a situation in which the light emitting point shakes due to convection.

The present disclosure is not limited to the above-described embodiment and the modified example. For example, the material and shape of each component are not limited to the materials and shapes described above and various materials and shapes can be adopted. The shapes of the first opening <NUM> and the second opening <NUM> are not limited to the circular shape and may be various shapes. The shapes of the first window member <NUM> and the second window member <NUM> are not limited to the circular plate shape and may be various shapes. The roughness of the surface 71a of the main body portion <NUM> and/or the outer peripheral surface 75a of the covering portion <NUM> is not limited to the case of forming the depression or the groove and may be performed by forming a protrusion or forming an unevenness portion. In the present disclosure, "A and/or B" means "at least one of A and B".

The joining material <NUM> may be a silver brazing material not doped with titanium or may be a titanium brazing material or a nickel brazing material. This is also the same in the joining materials <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. In the above-described embodiment, two second openings <NUM> are formed, but only one second opening <NUM> may be formed and three or more second openings <NUM> may be formed. A material forming the housing <NUM> may be a light shielding material which does not transmit (interrupts) the first light L1 and the second light L2 and may not be necessarily a metal material. An insulating material, for example, ceramic or the like may be used. The first electrode <NUM> and the second electrode <NUM> may be omitted. Also in this case, plasma can be generated at a focal point by irradiating the discharge gas G1 with the condensed first light L1.

The first window member <NUM> may be formed of diamond and the second window member <NUM> may be formed of sapphire. Alternatively, both the first window member <NUM> and the second window member <NUM> may be formed of sapphire or diamond. When using UV light, the first window member <NUM> and/or the second window member <NUM> may be formed of magnesium fluoride or quartz. The first window member <NUM> and/or the second window member <NUM> may be formed of Kovar glass.

Claim 1:
A light emitting sealed body comprising:
a housing (<NUM>) which stores a discharge gas (G1) and is provided with a first opening (<NUM>) to which first light (L1) is configured to be incident along a first optical axis (A1) and a second opening (<NUM>) from which second light (L2) is configured to be emitted along a second optical axis (A2), wherein the first light (L1) is laser light configured to maintain plasma generated in the discharge gas (G1) and the second light (L2) is light from the plasma;
a first window portion (<NUM>) that hermetically seals the first opening (<NUM>) and transmits the first light (L1);
a second window portion (<NUM>) which hermetically seals the second opening (<NUM>) and transmits the second light (L2), and
a first electrode (<NUM>) and a second electrode (<NUM>) which face each other with an intersection between the first optical axis (A1) and the second optical axis (A2) interposed therebetween,
wherein the housing (<NUM>) is formed of a light shielding material which does not transmit the first light (L1) and the second light (L2),
wherein an internal space (S3) is defined by the housing (<NUM>), the first window portion (<NUM>), and the second window portion (<NUM>) and the internal space (S3) is filled with the discharge gas (G1),
wherein the first opening (<NUM>) and the second opening (<NUM>) are disposed so that the first optical axis (A1) and the second optical axis (A2) intersectable with each other,
characterized in that the housing (<NUM>) is formed of a metal material, and
wherein the first electrode (<NUM>) is fixed to the housing (<NUM>) via an insulation member (<NUM>) and is electrically separated from the housing (<NUM>) and the second electrode (<NUM>) is electrically connected to the housing (<NUM>).