Abstract: A fluid sterilization device includes a straight pipe that constitutes a flow passage extending in a longitudinal direction, and a light source that emits ultraviolet light in the longitudinal direction toward a fluid flowing in a laminar state within the flow passage. The light source includes a light emitting element for emitting ultraviolet light and emits ultraviolet light so as to provide an intensity distribution on a cross section of the flow passage perpendicular to a longitudinal direction, in which the ultraviolet intensity in an area near the center is higher than the ultraviolet intensity around the area.

Abstract: A light-emitting module includes: a package substrate that is provided with a recessed portion having an opening at an upper surface thereof; a light-emitting device that is housed in the recessed portion; a window member that is provided on the upper surface such that the window member covers the opening; and a sealing portion that bonds the package substrate and the window member. The window member includes a lens portion facing the light-emitting device and a flange portion that projects from the lens portion and bonds to the sealing portion. The lens portion and the flange portion are formed of the same glass material.

Abstract: In a water purification apparatus, a light source irradiates the water, passing through the flow passage, with ultraviolet light. The light source has a light emitting diode that emits the ultraviolet light whose wavelength is contained in a bandwidth of 220 nm or above to less than 300 nm, and the optical output in this wavelength bandwidth is in a range of 1 W to 50 W. The flow passage passes the water at a flow rate of 5 mL/second to 250 mL/second. The flow passage is formed by a wall surface having a tubular shape. A window through which the ultraviolet light is passed is provided in at least part of the wall surface.