A flame detector that includes a spacer, a UV transparent window, and a UV sensing elements. The spacer has a spacer wall that extends along a first axis between a first spacer end and a second spacer end. The UV transparent window is disposed at the first spacer end. The spacer wall and the UV transparent window define a gas space. The UV sensing elements is disposed within the gas space.

A flame detector that includes a spacer, a UV transparent window, and a UV sensing elements. The spacer has a spacer wall that extends along a first axis between a first spacer end and a second spacer end. The UV transparent window is disposed at the first spacer end. The spacer wall and the UV transparent window define a gas space. The UV sensing elements is disposed within the gas space.

The present invention improves sensitivity of the ultraviolet band of a photoelectric surface. A photoelectric surface includes a window material that transmits ultraviolet rays, a conductive film that is formed on the window material and has conductivity, an intermediate film 4 that is formed on the conductive film and is formed of MgF.sub.2, and a photoelectric conversion film that is formed on the intermediate film 4 and is formed of CsTe. Since the photoelectric surface includes the intermediate film 4 formed of MgF.sub.2, the sensitivity of the ultraviolet band is improved.

An electron tube includes a housing having an internal space airtightly sealed, and an electrode configured to generation or detection of energy by electron emission in the internal space. The housing has a main body part made of an insulating material and formed with a recess constituting the internal space, and a lid part fixed to the main body part so as to close an opening of the recess. The recess expands toward the opening side. The main body part is fixed with a penetrating member that is electrically connected to the electrode and passes through the main body part. The penetrating member has an internal space projecting part that projects from a bottom surface of the recess into the internal space.

The present invention improves sensitivity of the ultraviolet band of a photoelectric surface. A photoelectric surface includes a window material that transmits ultraviolet rays, a conductive film that is formed on the window material and has conductivity, an intermediate film 4 that is formed on the conductive film and is formed of MgF.sub.2, and a photoelectric conversion film that is formed on the intermediate film 4 and is formed of CsTe. Since the photoelectric surface includes the intermediate film 4 formed of MgF.sub.2, the sensitivity of the ultraviolet band is improved.

A device (1), such as a detector or imaging device, for detecting ultraviolet light, is described. The device comprises a housing (4) for a chamber. Disposed within the housing is a charge carrier multiplier structure (9) comprising a dielectric sheet (10) having first and second opposite faces (11, 12) and having an array of holes (16) traversing the dielectric sheet between the first and second faces. The device includes a photocathode (13) supported on the first face of the dielectric sheet, having a work function of less than 6 eV. The device includes an anode (14) supported on the second face of the dielectric sheet.