Abstract: The method of the invention consists, on the one hand, in serially recording on a tape of photosensitive film a succession of volume holograms each relating respectively to an item of information of a corresponding document to be made secure, each of these holograms being accompanied by an identification and positioning code printed on the same film, in developing and in fixing the holograms thus recorded, and on the other hand in printing at the same time the identity documents with their individual identification codes which are the same as those of the respective corresponding holograms, in adding an adhesive to the holograms after their fixing, and in adhesively bonding together each hologram and the corresponding document after verifying that their respective identification codes match.

Abstract: The method of the invention consists, on the one hand, in serially recording on a tape of photosensitive film a succession of volume holograms each relating respectively to an item of information of a corresponding document to be made secure, each of these holograms being accompanied by an identification and positioning code printed on the same film, in developing and in fixing the holograms thus recorded, and on the other hand in printing at the same time the identity documents with their individual identification codes which are the same as those of the respective corresponding holograms, in adding an adhesive to the holograms after their fixing, and in adhesively bonding together each hologram and the corresponding document after verifying that their respective identification codes match.

Abstract: A document includes at least one drawing or data produced, for example, by printing. In addition, this document includes a hologram representing part of the document. The hologram of this document is recorded using a system including a prerecorded or electrically controllable optical modulator in which the image of at least part of the document is recorded. This modulator is designed to be combined with a layer of photosensitive material. A first reference wave illuminates the layer of photosensitive material. A second wave incident on the modulator and giving rise to a third object wave is also transmitted to the layer of photosensitive material in order to interfere with the reference wave in this layer.

Abstract: A document includes at least one drawing or data produced, for example, by printing. In addition, this document includes a hologram representing part of the document. The hologram of this document is recorded using a system including a prerecorded or electrically controllable optical modulator in which the image of at least part of the document is recorded. This modulator is designed to be combined with a layer of photosensitive material. A first reference wave illuminates the layer of photosensitive material. A second wave incident on the modulator and giving rise to a third object wave is also transmitted to the layer of photosensitive material in order to interfere with the reference wave in this layer.

Abstract: A document includes at least one drawing or data produced, for example, by printing. In addition, this document includes a hologram representing part of the document. The hologram of this document is recorded using a system including a prerecorded or electrically controllable optical modulator in which the image of at least part of the document is recorded. This modulator is designed to be combined with a layer of photosensitive material. A first reference wave illuminates the layer of photosensitive material. A second wave incident on the modulator and giving rise to a third object wave is also transmitted to the layer of photosensitive material in order to interfere with the reference wave in this layer.

Abstract: In a method for the making of a secured document, a layer of bonder is prepared on at least one face of the document; one or more information elements and/or images are printed on a first face of an information transfer sheet; the first face of the information transfer sheet is applied to the layer of bonder of said face of the document. In this way, the information elements are printed on a transfer sheet that has no layer of bonder and yet there are obtained information elements that get merged into the layer of bonder.

Abstract: Process for acquiring fingerprints, characterized in that it comprises the following steps:coating, with the aid of an ink, the surfaces of the fingers of a hand whose prints are to acquired;pressing a pad (2) of flexible material against the said coated surfaces;pressing the pad against a recording support (3). According to this process, the print is therefore taken on an intermediate pad and subsequently transferred to a paper support.

Abstract: An identity card or credit card type of card is equipped with a validity-checking device that makes it possible to do away with the use of complementary, sophisticated checking equipment. It results from the association of a structure S.sub.1 comprising at least one layer of piezoelectric material and a structure S.sub.2 comprising a material capable of switching electrically between two optical states (I) and (II) that are different in terms of ocular perception. During the bending of the card, the validity or non-validity of the card can be attested to by the appearance or non-appearance of the validity of the card.

Abstract: A method for recording pictures wherein a material to be scanned by a laser beam comprises a first layer laid on a substrate to form a picture zone and a reading zone and a second layer laid on the picture zone only which is capable of absorbing laser radiation. The laser beam is capable of double relative motion with respect to the above material with a first fast motion along a first axis and with a second motion, slow in comparison with the first motion, along a second axis which, for example, may be perpendicular to the first axis. The power of the laser beam is modulated as a function of the information to be recorded in synchronism with the above mentioned first motion.

Abstract: The optical head in the recording-reading device of a data carrier comprises a semiconductor laser source. A lens makes it possible to focus the beam from this source on to the data carrier via a reflecting or deviating mirror. According to the invention the rotation axis of this mirror is in the plane of the entrance pupil and of the focus of the focusing lens.

Abstract: A mobile pre-etched data carrier is provided in which the pre-etching is formed by a succession of discrete non continuous elements materializing the mean axis of the tracks. The spatial distribution of these discrete elements may be uniform or not. In a first embodiment, each discrete element is formed by a smooth track section. In a second embodiment, each discrete element comprises several sections defining a particular code. In other preferred variations of the invention, each element comprises, besides a portion centered on the mean axis of the tracks, one or more portions offset with respect to the axis. Finally, each of the pre-etchings may itself be preceded by an additional pre-etching element used for the purpose of synchronization. The tracking device comprises photodetector means, measuring circuits comprising sampler-inhibitors or storage integrator circuits and sampling circuits. A radial tracking error is formed from the evolution of the signals detected during successive passages.

Abstract: A process and device for focussing a light energy beam on a data carrier comprising sites fromed of virgin areas free from any data recording provided along tracks and serving as reference plane for said focussing. In a preferred variation, these areas are preceded by flags associated with a specific code. Control is achieved by measuring the deviation between the plane of focussing of a beam into a spot scanning the tracks and the reference plane formed by the surface of the virgin areas. Between two passages of these areas of the measurements are stored. The focussing error signal is obtained by filtering these measurements.

Abstract: The device according to the invention realize the following steps:(a) recording of binary test words on an optical disc associated to distinct engraving optical powers and comprising monotonous series of "1" and "0" logic bits of equal duration;(b) reading of these words;(c) measurement of the durations of these bits in the "1" state and bits in the "0" state,(d) determination of the optical power for which this ratio is closest to one;(d) elaboration and putting in memory of a control signal allowing to obtain this power.In a preferred variant, several test words are recorded and an interpolation is carried out between the measurements.

Abstract: The optical head in the recording - reading device of a data carrier comprises a semiconductor laser source. A lens makes it possible to focus the beam from this source on to the data carrier via a reflecting or deviating mirror. According to the invention the rotation axis of this mirror is in the plane of the entrance pupil and of the focus of the focusing lens.

Abstract: A device makes it possible to eliminate the imbalance of a deviating mirror of an optical system which illuminates a data medium or support when that mirror is subject to rapid displacement. The imbalance is cancelled by the use of a photodetector device which receives the light reflected by a reflecting element positioned around the objective of the optical system which illuminates the medium. A control device then makes it possible to control the position of the mirror based upon the light given off by the reflecting element.

Abstract: The process makes it possible to generate on the basis of discrete preetching elements or flags, the radial tracking error and/or focusing error signals. The flags comprise portions displaced with respect to the mean axis of the tracks to be followed. According to a first variant, each track comprises portions displaced on either side of the axis. According to a second variant the flags comprise portions alternately displaced to one and then the other side thereof. In response to the passages of these portions, windows are generated and the pulses supplied by the photodetectors of the interaction of these portions on the focused scan beam are compared between successive windows.

Abstract: A process and device for focussing a light energy beam on a data carrier comprising sites formed of virgin areas free from any data recording provided along tracks and serving as reference plane for said focussing. In a preferred variation, these areas are preceded by flags associated with a specific code. Control is achieved by measuring the deviation between the plane of focussing of a beam into a spot scanning the tracks and the reference plane formed by the surface of the virgin areas. Between two passages of these areas the measurements are stored. The focussing error signal is obtained by filtering these measurements.

Abstract: The angular velocity of an information element contained in the precut track of an information carrier disk is controlled by means of a concentric circular ring located internally with respect to the precut track and constituted by mark zones uniformly spaced in angular sectors. A light beam is projected onto the circular ring and the emergent beam is modulated as a function of the mark zones and blank zones which form the circular ring. Errors arising from eccentric displacement of the track can thus be corrected and the rate of travel of information can be controlled in relation to the reading or recording light beam.

Abstract: A mobile pre-etched data carrier is provided in which the pre-etching is formed by a succession of discrete non continuous elements materializing the mean axis of the tracks. The spatial distribution of these discrete elements may be uniform or not. In a first embodiment, each discrete element is formed by a smooth track section. In a second embodiment, each discrete element comprises several sections defining a particular code. In other preferred variations of the invention, each element comprises, besides a portion centered on the mean axis of the tracks, one or more portions offset with respect to the axis. Finally, each of the pre-etchings may itself be preceded by an additional pre-etching element used for the purpose of synchronization. The tracking device comprises photodetector means, measuring circuits comprising sampler-inhibitors or storage integrator circuits and sampling circuits. A radial tracking error is formed from the evolution of the signals detected during successive passages.

Abstract: The invention relates to devices for optically transcribing in a track carried by a support medium data to be written in or read out. The invention provides a pre-engraved track follower device for a transcription device in which a loop for radial control of the reading spot scanning the track is provided with sampling means taking samples during scanning of nonpost-engraved parts of a pre-engraved track, said scanning corresponding to a data write or read phase. The invention applies more particularly for digital data transcription devices using a single spot for locating a pre-engraved track and since optically writing data therein.