Abstract: An imaging installation, especially for digital type radiology, comprises a pick-up tube television camera with no remanence or low remanence with a non-linear element producing a remanence of the image signal given by the camera. The remanence varies with the level of the signal. When a recursive filter is used to obtain this remanence which is variable with the signal level, the modulation f.sub.2, introduced by the modulator connected to the output of this filter by a frames memory, is defined by the function: f.sub.2 (x)=x[.lambda.(1-g(x))+.mu.g(x)],a formula in which x is the ratio between the signal applied at the input of this modulator and the maximum value of the input signal, .lambda. and .mu. are constants, and g (x) is a linear function of x meeting the conditions: g (0) and g (1)=1.

Abstract: A radiological scanning apparatus for forming an image of an object on a film by scanning said object with a flat fan shaped beam. The film is conformed so as to form a surface of revolution. The surface of revolution is, on the one hand, moved in the same movement as the scanning movement of said beam, and on the other hand it is rotated about its axis of revolution so as to renew a surface exposed to said beam in order to reduce the dimension of said film considered in the direction of said scanning movement.

Abstract: In a radiology installation equipped with a picture-tube video camera for producing images in rapid succession, the electron beam of the camera tube has a first intensity at the time of readout of one image on the sensitive tube surface and a second non-zero intensity of substantially lower value than the first between readout of one image and write-in of the next. A control circuit for modifying the grid voltage of the camera tube is accordingly provided for varying the intensity of the electron beam.

Abstract: A picture taking tube with pyroelectric target and a process for determining the axes of least expansion of the target are provided. A connection is formed between the two electrodes of the target and the point of contact of this connection with the electrode deposited on the target is situated in the vicinity of one of the axes of least expansion of the target.

Abstract: A bipolar element having a non-linear conductivity characteristic is constituted by a semiconductor body placed between two dielectric layers, a source electrode, a drain electrode and a grid electrode. The grid electrode is constituted by a first grid electrode part electrically connected to the drain electrode and a second grid electrode part electrically connected to the source electrode. This bipolar element is adapted to be used as a commutating component, especially in visualization or display devices.

Abstract: A matrix having photosensitive elements formed by thin-film technology on the same dielectric substrate and disposed at each crossing point of perpendicular lines and columns. An addressing MOS transistor, formed by thin-film technology and associated with each photosensitive element, receives periodically on its grid an enabling signal applied simultaneously to all the addressing transistors in the same line of photosensitive elements and is connected for transferring to a video amplifier the electric signals provided by each addressed line of photosensitive elements. An amplifier for these signals is associated with each photosensitive element and is formed by thin-film technology.