Abstract: A surface pattern (1) is composed of elements (2 to 5) which are arranged in a mosaic-like fashion and of which at least one pattern is formed from a background element (4) and a pixel (2) with microscopically fine relief structures diffracting visible light. The surface elements (3) and the element portions (5) either contain the microscopically fine relief structures diffracting visible light or they comprise reflecting or scattering surfaces. Arranged in the pixel (2) is a first diffraction grating B1 and arranged in the background element (4) is a second diffraction grating B2, wherein the first diffraction grating B1 and the second diffraction grating B2 are a superimposition of at least two different, microscopically fine relief structures F1 and F2 diffracting visible light. The first diffraction grating B1 and the second diffraction grating B2 differ only by virtue of a relative phase shift &Dgr;&phgr; between the relief structure F1 and the relief structure F2.

Abstract: An electrostatic chuck is formed by: providing a conductive base member; machining a pattern of ridges in the top surface of the base member; providing through holes in the base member; inserting insulated contact posts into through holes and joining same to the base member in such manner that the contact posts extend above the top surface of the base member; depositing a first insulating layer over the base member top surface, ridges and the contact posts, the thickness of the insulating layer being less than the height of the contact posts above the base member surface; removing the first insulative layer from the top of the contact posts and removing a portion of the contact posts in such manner that the contact posts are flush with the surrounding first insulating layer; depositing a conductive layer over the first insulating layer and the tops of the contact posts, the thickness of the conductive layer being approximately the height of the ridges; grinding the top surface of the base member flat to the p

Abstract: An optically variable surface pattern includes at least one graphic representation producing an achromatic impression when viewed in visible light over a certain angular range without noticeable color fringes occurring in the adjoining angular ranges. A plane surface portion includes a grating structure which disperses incident light with comparable intensity into a cone within a predetermined angle range regardless of differing wavelength. An overlap of several successive high orders of diffraction results in a recombination of the dispersed light to white light at any diffraction angle within the cone. The surface portion viewed from a direction within the cone reflects white light, in contrast to a simple flat mirror which has a very narrow range of specular reflection. At viewing angles outside the cone, the surface portion is dim or dark grey. The shape of the surface portion is then recognized as an area white lit or dark depending upon a particular viewing angle relative to incident light.

Abstract: An optical information carrier is in the form of a composite laminate having a carrier foil. The underside and the top side of the carrier foil are provided with optically effective structures. The carrier foil is approximately transparent for light in a predetermined spectral range. The structures allow light impinging on the top side to penetrate at least partially into the composite laminate. The structures on the underside are microscopically fine relief structures which are covered with a base layer whose refractive index differs from the refractive index of the carrier foil in at least a portion of the electromagnetic spectrum so that the structures on the underside at least partially reflect and diffract the light which has penetrated into the composite laminate. The structures on the top side in turn modify the diffracted light. The interplay of the two structures provides manifold characteristic optical effects such as moire effects and light guide effects.

Abstract: A surface pattern has two surface portions with microscopically fine, light-diffracting relief structures. The relief structures are in the form of grating structures GS1 and GS2, respectively, which are composed of at least two superimposed gratings G1 and G2, G3 and G4, respectively. The light-diffracting properties of the gratings G1 to G4 are so selected in accordance with various criteria that novel optical effects which cannot be holographically copied can be achieved with the grating structures GS1 and GS2. Such surface patterns are suitable as optical security elements for documents or articles of all kinds as well as packing foils.

Abstract: Electrostatic chucks are disclosed in which a conductive pole piece is provided with a flat top surface, sidewall and a perimeter with radiused corners connecting the top surface to the sidewall. The perimeter and sidewall are coated with a ceramic insulative material covering the radiused corners. The top surface is coated with a ceramic semiconductive material. Then the surfaces of the pole piece not covered by ceramic material are anodized in such a manner that the intersections between anodized pole surfaces and ceramic material are below the pole piece top surfaces.

Abstract: An electrostatic chuck employs thermoelectric cooling technology. The chuck includes a conductive circular base with an upper ring portion forming a first pole piece electrically isolated from an annular portion forming a second pole piece. The upper surface of the pole pieces have a dielectric material formed thereon and together form the electrostatic clamping surface for an article to be held thereon. The backside is provided with an annular recess containing a plurality of thermoelectric devices or modules and intervening spokes. The devices are covered with a heat sink or cooling plate through which a fluid such as water is circulated. A retaining back ring covers the water plate which is secured to the base by bolts. Uniform pressure is applied to the water plate and modules by means of spring washers inserted between back ring and water plate.

Abstract: An information carrier has at least one diffraction pattern which is formed from microscopically fine relief structures and which, upon being illuminated with coherent light, produces in two spatially separate directions, a first and a second image of an object. The images can be rendered visible on a screen or analysed by means of photodetectors. The two images have strong-light and/or weak-light picture elements and includes a symmetry insofar as a weak-light picture element of the second image can be associated with a strong-light picture element of the first image and vice-versa. Such information carriers are suitable as security elements for documents of all kinds such as, for example, banknotes, passes, identity cards, credit cards, etc., wherein at least a part of the security information is not visible under incoherent illumination conditions.

Abstract: In a method of transferring a security element which is in the form of a laminate with a carrier foil and with a thermally activatable adhesive layer for connection to a substrate onto a document the adhesive layer is brought into contact with the substrate and locally heated by the supply of heat energy through the laminate. After the adhesive layer cools if necessary the carrier foil can be pulled off the substrate, in which case the carrier foil, at the locations adhering to the substrate, is detached from the rest of the laminate and the laminate tears along the boundary between the adhering and the non-adhering locations so that only the adhering locations of the laminate remain behind on the substrate. In particular a laser beam or an array of laser or light emitting diodes is suitable for the supply of heat energy. The laminate preferably has diffraction structures or layers producing optical interference effects.

Abstract: An information carrier is in the form of a composite laminate with a first, a second and a third layer having refractive indices n3, n4, n5 respectively. The second layer forms structures by only partially covering the first layer. The third layer covers over the second layer or the first layer in direct contact therewith. The surface on the first layer has surface elements with first and second diffraction structures which produce a visually verifiable authenticity feature or which serve for reading out the information contained in the structures formed by the second layer. The refractive indices n4 and n5 are substantially real in the visible range and therefore the second and third layers are transparent. The differences .vertline.n4-n3.vertline. and .vertline.n5-n3.vertline. are greater than 0.2 over large parts of the visible range so that the first diffraction structures produce visible diffraction effects independently of the structures formed by the second layer.