Abstract: This relates to an identification system for authenticating labels and cards. Each label or card would be provided with authenticating characters which are printed in color and which are at least in part in overlapping relation so as to make it difficult to identify the individual characters by eye. However, when a pair of overlapping characters is viewed through a colored filter, depending upon the color of the filter, one or other of the two superimposed characters would appear. By providing the authenticating characters in a preselected arrangement and utilizing colored filter segments in a similar preselected arrangement, only those authenticating characters which form part of the authenticating information would appear.

Abstract: The present invention is directed to a photocopy prevention film applied to a document to be protected that comprises either a volume holographic refraction grating or a surface holographic refraction grating. The refraction grating is bonded to a document and either causes normally scattered light to be focused toward the photoreceptors of a photocopy machine or causes light normally reflected toward the receptors to be scattered away from the receptors. The film is created by splitting a coherent laser beam into a reference beam and a target beam. The target beam reflects off of a special target and onto a photographic emulsion. The reference beam is also incident to the photographic emulsion. The beam reflected from the target and the reference beam create interference planes within the emulsion which can be developed to create differing refractive index planes within the emulsion or etched away to create a surface grating.

Abstract: A sheet containing an integrated-directional, half-tone image. Each sheet may contain one or more such images. Also a method for forming such images in microlens sheetings comprising directly a highly collimated light through an interposed half-tone mask.

Abstract: Color control in a Denisyuk type hologram having interference fringes lying generally parallel to the substrate is effected by subjecting the initially produced hologram to resensitizing, controlled re-exposure, second development and second bleaching steps, of which the effect is to remove silver produced by the second exposure so as to enable the playback interference fringes to move closer together.

Abstract: A credit card is made with a number of optical fibers sandwiched in the card. Some of the fibers intersect opposite edges of the card in a random fashion and provide a unique code characteristic of the card when light is directed into one edge and detected at the other. When cards are made in quantity, the fiber are added in a random fashion providing a unique code for each card.

Abstract: There is disclosed a tamper-free identification system, such as an ID card, comprising an information-bearing substrate made of a flexible but substantially rigid material, a partial light reflector superposed over said substrate which produces a substantially nondepolarizing light reflection, and a substantially transparent 90.degree. retarder superposed over said reflector. Said identification card can be manufactured at low cost using techniques known in the art, and with the aid of a simple and inexpensive analyzer such as a linear light polarizer, fraudulent alternations of the identification card can readily be detected.

Abstract: Security paper with luminescing authenticity characteristics which after excitation with invisible light emit exclusively invisible light of different wavelengths as authenticity signal. The luminophores can be included in the printing ink used or they can be added to the paper material in the manufacture of the paper material. A corresponding test apparatus makes it possible to check the authenticity of the security paper in the presence of customers but unnoticed by them; thereby the invisibility of the test signal and the authenticity signal are taken advantage of and the test device is hidden behind a plate non-transmissive for visible light which however is transmissive for the test signal and for the authenticity signal.

Abstract: An information bearing credit or identification card in which pieces of a diffraction grating, preferably an embossed hologram, are randomly distributed in a plastic or paper card so that light reflecting therefrom uniquely and visually differentiates the grating and hence the card. The pieces may be mixed in the plastic pig or with the paper prior to rolling or sprinkled in the plastic or other substrate during rolling.

Abstract: An identification card having photographically recorded individualizing data is provided. The photographically recorded data are interspersed with a security pattern in transparent ink. This pattern is printed onto the photographic layer before the photographic data are recorded. The photographic recording process is carried out in such a way that there is no darkening under the security pattern. The security pattern, recognizable through the transparent printing ink, is thus also impressed upon the photographically recorded data.