Abstract: A device for optically reading a recording medium is provided, in which a polarization beam separator includes a transparent plate having a phase network associated with a birefringent material, the refraction index of this material having a first refraction index for the polarization of an incident beam and a second refraction index for the polarization of a reflected beam. Thus, in accordance with the embodiment, the detection devices are placed substantially along the emission axis of the optical source.

Abstract: The invention concerns a method for the detection of the end of grinding of at least one thin layer magnetic head, the head comprising, at the stage of implementation of said method, an active face, formed by two magnetic poles (1, 2) separated by a gap (4). The method comprises the following steps:deposition of a conductive layer (7) on the entire active face (3)etching of the active face coated with said conductive layer;deposition of a layer of dielectric material (8) on the etched active face;grinding of the active face starting from the face that is free of the layer of dielectric material (8) until total removal of that part of the conductive layer (7) located above the gap (4), this removal being detected by the sudden variation in resistivity between the two magnetic poles (1, 2).

Abstract: A method for achieving the planar surface of an active face for magnetic recording/reading heads. The planar surface of the active face is obtained by grinding, the active face being of the type where, before the grinding operation, the level of the material forming the gap is recessed with respect to the magnetic poles, the method comprising depositing over the recess a thin layer of non-magnetic material with a thickness at least equal to the recess of the gap. The non-magnetive thin layer may then be ground to obtain the planar surface of the active face.

Abstract: The invention relates to thermo-optic writing on an information support comprising a substrate on which there is deposited an organic sub-layer covered by a metal layer.The invention provides a writing process which consists in creating in the metal layer a plastic deformation due to the thrust exerted by the localized swelling of the sub-layer. The writing produces a relief impression without piercing of said metal layer.

Abstract: Thermo-optic writing on an information support in which an organic sublayer covered by a metal layer is deposited on a substrate. A plastic deformation due to the thrust exerted by the localized swelling of the sub-layer is created in the metal layer to produce a relief impression without piercing of the metal layer.

Abstract: The present invention relates to data-carrier intended for the high-density recording of information by the use of an etching radiation beam. The data-carrier comprises a substrate upon which there are deposited a very thin film which is absorbent at the wavelength of the etching beam, and a film which is thermodegradable at a temperature lower than the degradation temperature of the absorbent film, the heat developed in the absorbent film being selectively diffused towards the adjacent thermodegradable film.

Abstract: This disc has a layer of an inscribable and optically legible recording material deposited on a transparent plate traversed by the recording or reading beam and protected from the outside by a cover formed for example by a metal sheet, whose two surfaces are fixed to the layer so as to form a space in front of the latter.

Abstract: This disc has a layer of an inscribable and optically legible recording material deposited on a transparent plate traversed by the recording or reading beam and protected from the outside by a cover formed for example by a metal sheet, whose two surfaces are fixed to the layer so as to form a space in front of the latter.

Abstract: The present invention relates to data-carrier intended for the high-density recording of information by the use of an etching radiation beam. The data-carrier comprises a substrate upon which there are deposited a very thin film which is absorbent at the wavelength of the etching beam, and a film which is thermodegradable at a temperature lower than the degradation temperature of the absorbent film, the heat developed in the absorbent film being selectively diffused towards the adjacent thermodegradable film.