Abstract: The device comprises a first path provided with an amplifier (1) amplifying in a first frequency band, and a second path provided with an amplifier (2) amplifying in a direction opposite to that of the first amplifier and in a second frequency band other than the first frequency band, a first filter element (L1) having a low pass characteristic for transmitting the signals of the first path, and a second filter element (C1) having a high pass characteristic for transmitting the signals of the second path. The two paths are combined by a third filter element (CA) having a high pass characteristic, arranged in series with a fourth filter element (LA) having a low pass characteristic, whose junction point is connected to ground by a matched impedance (ZCA), and a signal polarity inverting element (TA) is inserted in series between two of the filter elements.

Abstract: An aluminum substrate which supports a scintillator transforms X-rays into visible or nearly visible light radiation which is converted into a flux of electrons by means of a photocathode. The flux produces a visible image on an exit screen through electro-optical means. A layer which absorbs the light radiation emitted by the scintillator in the direction of the aluminium substrate is inserted between the aluminium substrate and the scintillator, the absorbing layer consisting of a material chosen from the following materials: titanium nitride, cadmium sulphide, (Cu, OhI.sub.2). A layer having a low optical index can be inserted between the scintillator and the photocathode. A chemical barrier may also be inserted between the scintillator and the photocathode. An electrically conductive and optically transparent layer can be inserted between the photocathode and the chemical barrier.