The present invention has as an object the provision of a light irradiation device capable of performing optical cleaning with high stability regardless of the transport speed of a workpiece. The light irradiation device of the present invention emits ultraviolet light to one surface of a band-shaped workpiece transported along a transport path, and includes a lamp house having an opening along a passing plane on a side of the one surface of the workpiece in the transport path, an ultraviolet lamp provided in the lamp house so as to extend in a width direction of the workpiece, gas supplier configured to supply a treatment-space gas into the lamp house, and an exhaust space forming member having an opening along a passing plane on a side of the other surface of the workpiece in the transport path. The treatment-space gas is produced by mixing a gas containing oxygen and/or water with an inert gas serving as a principal component, and a shielding body for forming a gas circulation resistance bottleneck between the shielding body and each edge part of the workpiece is provided in the opening of the lamp house.

A ultraviolet irradiation apparatus includes: a first electrode block and a second electrode block located apart from each other in a first direction or located in an electrically-insulated state in the first direction; a recessed groove formed on a side surface of each of both the blocks; a first discharge lamp partially fitted into the recessed grooves formed in both the blocks and located across the both blocks; a power supply part for supplying electrical power to the first discharge lamp; a first current-carrying member electrically connecting the first electrode block and the power supply part; a second current-carrying member capable of electrically connecting the second electrode block and the power supply part at an electrical potential different from that of the first current-carrying member; and a light irradiation window for extracting ultraviolet light emitted from the first discharge lamp to outside.

A light emitting sealed body includes: a housing containing light-emitting gas in an internal space, on which laser light for maintaining a plasma generated in the light-emitting gas is incident; and a charging pipe including a first end portion and a second end portion and connected to the internal space at the first end portion. The second end portion of the charging pipe is sealed by being crushed. The second end portion of the charging pipe is covered with a covering member consists of an inorganic material. The covering member is covered with a cap member consists of a metal material.

A light emitting sealed body includes: a housing containing light-emitting gas in an internal space, on which laser light for maintaining a plasma generated in the light-emitting gas is incident; and a charging pipe including a first end portion and a second end portion and connected to the internal space at the first end portion. The second end portion of the charging pipe is sealed by being crushed. The second end portion of the charging pipe is covered with a covering member consists of an inorganic material. The covering member is covered with a cap member consists of a metal material.

A light emitting sealed body includes: a housing containing light-emitting gas in an internal space; a first window portion which is provided to the housing and on which first light that is laser light for maintaining a plasma generated in the light-emitting gas is incident; a second window portion provided to the housing and from which second light that is light from the plasma is emitted; and a getter portion including a getter material and disposed in an irradiation region of the first light inside the housing.

A light emitting sealed body includes: a housing containing light-emitting gas in an internal space; a first window portion which is provided to the housing and on which first light that is laser light for maintaining a plasma generated in the light-emitting gas is incident; a second window portion provided to the housing and from which second light that is light from the plasma is emitted; and a getter portion including a getter material and disposed in an irradiation region of the first light inside the housing.

A light emitting sealed body includes: a housing containing light-emitting gas in an internal space and formed with an opening on which first light is incident and/or from which second light is emitted, wherein the first light is laser light for maintaining a plasma generated in the light-emitting gas and the second light is light from the plasma; and a window member that transmits the first light and/or the second light at the opening. The window member is joined to the housing by a joining material consisting of a material containing gold.

A light emitting sealed body includes: a housing containing light-emitting gas in an internal space and formed with an opening on which first light is incident and/or from which second light is emitted, wherein the first light is laser light for maintaining a plasma generated in the light-emitting gas and the second light is light from the plasma; and a window member that transmits the first light and/or the second light at the opening. The window member is joined to the housing by a joining material consisting of a material containing gold.

A light emitting sealed body includes: a housing containing light-emitting gas in an internal space; a first window portion provided to the housing and on which first light that is laser light for maintaining a plasma generated in the light-emitting gas is incident; and a second window portion provided to the housing and from which second light that is light from the plasma is emitted. The second window portion includes a second window member made of a material containing diamond. A protective layer made of an inorganic material is formed at least on a surface of the second window member on a side of the internal space.

A light emitting sealed body includes: a housing containing light-emitting gas in an internal space; a first window portion provided to the housing and on which first light that is laser light for maintaining a plasma generated in the light-emitting gas is incident; and a second window portion provided to the housing and from which second light that is light from the plasma is emitted. The second window portion includes a second window member made of a material containing diamond. A protective layer made of an inorganic material is formed at least on a surface of the second window member on a side of the internal space.