Abstract: An electrochemical battery with mobile electrodes of the so-called "reserve" type. According to one characteristic of the invention, the battery includes a holder for holding the electrodes outside the cells during a storage period of the battery, and for placing these electrodes inside the cells in order to activate the battery.

Abstract: The luminescent screen comprises blocks having an optical transparency of less than 1. The blocks are placed between the grains of the first layer of luminescent material and the transparent substrate and have a cross-sectional area which is equal at a maximum to that of the grains. Said blocks are formed by means of a selective plasma etching operation in which the grains of the first layer of luminescent material are employed as a mask.

Abstract: A variable gain R.I.I. target is obtained by using an optical fibre board, whose face on the R.I.I. side has blind holes containing two types of granular luminescent materials having different luminous efficiencies and which are separated by a barrier layer. The electron beam from the R.I.I. photocathode is subject to two different accelerating voltages, the lower accelerating voltage exciting the luminescent material with the lower luminous efficiency and the higher accelerating voltage exciting the luminescent material with the higher luminous efficiency. Application to image intensifier tubes, used more specifically in radiology and fluoroscopy.

Abstract: In an X-ray image intensifier consisting of a scintillator screen associated with a photocathode, an electron-optical system and an output screen on which a strong visible image appears, resolution is improved by providing the scintillator screen, formed by a layer of cesium iodide doped with sodium deposited onto the substrate, a structure of needles approximately micrometers in diameter which are kept in the form of separate needles during the subsequent heat treatment by virtue of the presence of silicon oxide in the cesium iodide lattice.

Abstract: In an X-ray image intensifier consisting of a scintillator screen associated with a photocathode, an electron-optical system and an output screen on which a strong visible image appears, resolution is improved by providing the scintillator screen, formed by a layer of cesium iodide doped with sodium deposited onto the substrate, a structure of needles approximately micrometers in diameter which are kept in the form of separate needles during the subsequent heat treatment by virtue of the presence of silicon oxide in the cesium iodide lattice.

Abstract: The screen comprises superimposed layers of phosphor crystals having fluorescences of different colors separated by an inert layer having a substantially uniform thickness. In one example, the layers are of green phosphor P1 (J.E.D.E.C.) (.lambda.=550 nm) and red phosphor yttrium vanadate activated with europium (.lambda.=610 nm), in a proportion of 3 to 4 mg/cm.sup.2 and 0.15 mg/cm.sup.2 respectively. The inert layer is silicon sesquioxide (Si.sub.2 O.sub.3), and has a thickness of 1.2 .mu.m. High luminances are obtained throughout the range of colors, for operating voltages ranging between 10 kV and 17 kV.

Abstract: In order to avoid losses in definition and contrast which are observed in image-converter tubes as a consequence of the light scatter taking place within the body of the scintillators of the input screens of these tubes, when said scintillators occur in the form of a continuous layer of material, the present invention provides for the formation within a layer of microscopic channels which are transversely disposed, the channels being formed by covering the substrate, prior to the deposition of the scintillator thereon, with a layer of a granular material, preferably glass balls. Application to radiology and scintillography.