Abstract: The invention relates to a method for the production of a multicolor hologram by means of a capture beam, wherein the utilized capture beam (6) has a plurality of beam bundles of the same wavelength. Advantageously, the multicolor hologram is produced by copying the structure of multiple single-color subholograms of a master hologram (1) in a copy layer (5) which is affixed parallel to the master hologram, by illuminating this copy layer with the single-color capture beam. Each beam bundle appears at a prespecified angle of incidence, wherein the angles of incidence are calculated in such a manner that the structure of a corresponding subhologram is produced in the copy layer. In this way, a falsification is nearly impossible.

Abstract: The invention relates to a method for the production of a multicolor hologram by means of a capture beam, wherein the utilized capture beam (6) has a plurality of beam bundles of the same wavelength. Advantageously, the multicolor hologram is produced by copying the structure of multiple single-color subholograms of a master hologram (1) in a copy layer (5) which is affixed parallel to the master hologram, by illuminating this copy layer with the single-color capture beam. Each beam bundle appears at a prespecified angle of incidence, wherein the angles of incidence are calculated in such a manner that the structure of a corresponding subhologram is produced in the copy layer. this way, a falsification is nearly impossible.

Abstract: A rain sensor, particularly for a motor vehicle, includes a light-conducting member arranged in an intermediate layer of a glass, and is designed as an optically closed system.

Abstract: A rain sensor for a motor vehicle, having a transmitter emitting radiation, a receiver, and a holographically embodied diffractive element that has a linear-grating-like structure.

Abstract: A rain sensor, particularly for a motor vehicle, includes a light-conducting member arranged in an intermediate layer of a glass, and is designed as an optically closed system.

Abstract: A rain sensor for a motor vehicle is proposed, having a transmitter (16) emitting radiation, a receiver (18), and a holographically embodied diffractive element (22a, 22b) that has a linear-grating-like structure.

Abstract: An apparatus for evaluating distinguishing authenticity features comprising diffraction elements on a document which is illuminated by an illumination source. The distinguishing authenticity element which is to be examined, diffracts the beam of the illuminating source and projects it onto an evaluating unit in the device. In order to be independent of the nature and location of the diffraction pattern, the diffraction pattern derived from the document to be examined is projected onto a screen and the image of the pattern recorded and evaluated by a camera (matrix or cells).

Abstract: An apparatus for evaluating distinguishing authenticity features comprising diffraction elements on a document which is illuminated by an illumination source. The distinguishing authenticity element which is to be examined, diffracts the beam of the illuminating source and projects it onto an evaluating unit in the device. In order to be independent of the nature and location of the diffraction pattern, the diffraction pattern derived from the document to be examined is projected onto a screen and the image of the pattern recorded and evaluated by a camera (matrix or cells).

Abstract: In an optical storage medium, preferably a CD or DVD, comprising a spiral track which consists of pits following one another, a hologram is superimposed in the recording region. To achieve a great security against faking by the superimposition with the hologram, without the good recognisability of the hologram being substantially impaired on its reconstruction, the hologram is introduced at least into one information carrier, for example into the surface region of the recording region including the pit.

Abstract: The invention relates to a moisture sensor in which light is coupled into a light guiding layer by a light source, undergoes total reflection there as long as the surrounding medium has a moisture lower than a threshold moisture and does not undergo total reflection if the moisture of the medium exceeds a threshold moisture, having an uncoupling element to uncouple the light from the light guiding layer and a detector for the uncoupled light. In accordance with the invention, a reflection hologram is provided on a part of the light guiding layer which, when a light ray is incident at the angle with which the light propagates in the light guiding layer, reconstructs a light ray which extends substantially counter to the incident light ray. The invention furthermore relates to a corresponding moisture sensor in which a pane, in particular an aeroplane or vehicle windscreen, is used as the light guiding layer.

Abstract: An information medium consists of an essentially circular or polygonal disk having at least two pairs of sides parallel to one another which have the same distance to one another in each pair. To reliably read stored data from such an information medium at high speed, a hologram is disposed on at least one side of the disk at its center or at the intersection of two crossing symmetry lines which can be reconstructed with a reference beam incident to the side at a right angle to a pattern consisting of essentially concentric circles, with the reference beam forming the axis of said pattern.

Abstract: A process for the manufacture of non-replicable holograms possessing authenticity features which are copies of a master hologram. To form a master hologram, a hologram is taken of a randomly structured optical element, for example of a ground glass screen or a diffusor. The resulting hologram forms an authenticity feature, with an optical system which leads to a hologram with a pattern of lines that are parallel to one another.

Abstract: A method for determining the authenticity of a hologram with the following steps:a) The hologram (1) to be checked is illuminated with a restoration ray (2):b) The diffraction ray (3) of the first order of the wave field created at the hologram is imaged on a first photo-sensitive element, in particular a CCD target (5), and brought to interference with a first reference ray (7);c) The diffraction ray (4) of the zeroth order of the wave field created at the hologram (1) is imaged on a second photo-sensitive element, in particular a CCD target (6) and brought to interference with a second reference ray (10);d) The intensity distributions created at the different photo-sensitive elements (5, 6) are correlated with each other for at least two phase relationships between the restoration ray (2) and the different reference rays (7, 10) to obtain a correlation intensity distribution for the relevant orders of diffraction; ande) The correlation intensity distributions determined for the relevant orders of diffractio