Abstract: A Zero-order diffractive filter comprising a first layer (1) with a periodic diffractive microstructure, forming a waveguide, and at least one adjacent second layer (2, 4, 5), wherein said first layer (1) has a refractive index that is higher than the refractive index of said second layer (2, 4, 5) by at least 0.2. At least one of said second layers (2, 4, 5) is a porous layer comprising nanopores. The period ? of the diffractive microstructure is between 100 nm and 3000 nm.

Abstract: The diffractive optical device (1) can be used as a security device in the fields of authentication, identification and security. It comprises a zero-order diffractive color filter (3). The diffractive color filter may consist of a microstructured high-index layer (32) embedded between two low-index layers (31, 33). A mirror layer (4) for reflecting towards the diffractive color filter (3) at least part of light transmitted through the diffractive color filter (3) are provided beneath the diffractive color filter. Thanks to the mirror layer (4), the device (1) has a much higher reflected intensity and much more complex spectra than prior-art diffractive color filters.

Abstract: A security device comprises first zero order diffractive microstructure (1) on a substrate, a second zero order diffractive microstructure (2), and an intermediate light transmissive layer (4) separating the two diffractive microstructures. The spacing (sn,n+1) between the first (1) and second (2) diffractive microstructures is small enough so that optical interferences are produced between the diffractive microstructures. A further light transmissive layer (3) covers the second diffractive microstructure (2).

Abstract: A zero order diffractive filter for polarised or unpolarised polychromatic light, comprises a grating line (10) microstructure (1) formed by a surrounding medium (12) with low index of refraction nlow and a waveguiding layer (11) with high index of refraction nhigh, the grating lines (10) having a period length ? that is smaller than the wavelength of light for which the filter is designed. A plurality of single nanostructures (2) with dimensions in the nanometre range is superposed on a first interface (13) between the surrounding medium (12) and the waveguiding layer (11).

Abstract: A tablet (4) for pharmaceutical use has on at least one part of its surface a diffractive microstructure (11) which generates diffraction effects which can be perceived in the visible spectral range and which serve as visual safety feature. The tablet (4) consists of a plurality of individual powder particles, where the diffractive microstructures (11) are impressed into the surface of the individual powder particles. A compression tool (1, 1a, 1b, 3) to produce such tablets (4) has on one pressing surface of the compression tool (1, 1a, 1b, 3) micro-structures (11), where said microstructures (11) have dimensions which are smaller than the dimensions of the individual crystallites (30) of the material of the pressing surface of the compression tool (1, 1a, 1b, 3). The micro-structures (11) of the compression tool can be produced for example by ion etching or by imprinting.

Abstract: The invention relates to a printed circuit board element (10) including at least one optoelectronic component (1) which is embedded in an optical, photopolymerizable layer material (13), and at least one optical waveguide (14) optically coupled thereto, which is structured in the optical, photopolymerizable material (13) by photon irradiation, wherein the component (1) comprises a curved deflection mirror (5) on its light transmission surface (3), which curved deflection mirror deflects the light radiation (15), for instance by 90°.

Abstract: A sensor which reacts on influences from an environment. The sensor includes a zero-order diffractive color filter. The zero-order diffractive color filter includes a high-index waveguide layer, a zero-order diffractive grating structure and a layer of an reactive material, wherein the reactive material is in contact with the environment and wherein the reactive material changes its optical properties upon interaction with the environment. The reactive material is embedded in the waveguide layer and/or the reactive material is located at a maximum distance d from the waveguide layer. The distancing is effected by an intra layer having a low index of refraction.

Abstract: The present invention relates to pigments comprising or consisting of a layer made of a material with an index of refraction that is higher than the index of refraction of the adjacent material by at least 0.25; whereas said layer has a zero-order diffractive micro-structure; whereas said layer acts as an optical waveguide and whereas said layer has a thickness between 50 nm and 500 nm; to processes for its manufacture and to its use. These pigments show a colour effect upon rotation and/or tilting, and it is believed that this colour effect is based on zero-order diffraction.

Abstract: A security device for the identification or authentication of goods is described. It comprises a stochastic pattern comprising structures having an average lateral structure size d and arranged such that an image of at least a part of the security device, when treated through 2D Fourier transformation and calculation of a corresponding Power Spectrum Density, may lead to a peak, in a spatial-frequency domain, having a position in this domain correlated to d and a size distribution value w which, when inverted, is correlated to a size distribution of the structures. The value w according to the invention is smaller than 2/d, so that when directing a coherent light beam on at least part of the structures a ring-shaped scattering speckle pattern is formed, on the basis of which d and w may be calculated to implement identification or authentication of the device.

Abstract: The present invention relates to an isotropic zero-order diffractive colour filter, to a method to manufacture an embossing tool and to a method to manufacture such a filter. The zero-order diffractive colour filter comprises diffractive microstructures and a wave-guiding layer, wherein the diffractive microstructures possess a short range ordering over at least four times the period of the microstructures, and the diffractive microstructures possess a long range disordering over length scales of more than 100 ?m.

Abstract: A zero order diffractive filter for polarised or unpolarised polychromatic light, comprises a grating line (10) microstructure (1) formed by a surrounding medium (12) with low index of refraction nlow and a waveguiding layer (11) with high index of refraction nhigh, the grating lines (10) having a period length ? that is smaller than the wavelength of light for which the filter is designed. A plurality of single nanostructures (2) with dimensions in the nanometre range is superposed on a first interface (13) between the surrounding medium (12) and the waveguiding layer (11).

Abstract: A Zero-order diffractive filter comprising a first layer (1) with a periodic diffractive microstructure, forming a waveguide, and at least one adjacent second layer (2, 4, 5), wherein said first layer (1) has a refractive index that is higher than the refractive index of said second layer (2, 4, 5) by at least 0.2. At least one of said second layers (2, 4, 5) is a porous layer comprising nanopores. The period ? of the diffractive microstructure is between 100 nm and 3000 nm.

Abstract: The present invention relates to a verification method of tablets, in particular pharmaceutical tablets. It further relates to an invisible secure marking or information which is a part of such tablet. The invention further relates to tablets suitable for such verification method, to processes for manufacturing such tablets and methods for reading the information.

Abstract: A diffractive optical filter comprises a bulk material (1) having a first refractive index, a volume diffraction grating structure (2,3) having a second, different, refractive index embedded in the bulk material (1), and a mirror (4) formed within or on the surface of the bulk material (1) behind the grating structure (2,3). By placing the mirror (4) immediately behind the grating structure (2,3) the diffractive structure is effectively doubled and consequently the number of effective optically active layer is doubled. Such diffractive optical filters may be used as diffractive identification devices bonded to articles whose authenticity needs to be established.

Abstract: An article (1) such as a medicinal tablet or a foodstuff, has a microstructured surface (2). White light incident on the microstructure will be reflected at a number of different wavelengths dependent on the angle of incidence of the white light on the structure. This structure can provide an indication of authenticity of the article.

Abstract: The present invention relates to Zero-order Diffractive filters (ZOFs), comprising a first layer having periodic diffractive microstructures and a second layer, wherein said first layer has a refractive index higher than said second layer by at least 0.2, and nanoparticles located in at least one of said layers which affect the refractive index of said at least one of said layers. The present invention further relates to methods of manufacturing such ZOFs, to the use such ZOFs e.g. in security devices and to the use of specific materials for manufacturing ZOFs.

Abstract: One or more zero-order diffractive pigments (ZOP) having both a particle distribution matrix material, and a layer of material in or on such a matrix material and having an index of refraction higher than that of the matrix material, and having a diffractive grating structure with a period in the range of 100 to 600 nm, which is smaller than the wavelength of light reflectable thereby in the zeroth reflection order. In such ZOPs the index of refraction of the matrix material is usually at least 0.25 less than that of the material of the layer, and the layer is typically of a thickness between 30 and 500 nm.

Abstract: A security device comprises first zero order diffractive microstructure (1) on a substrate, a second zero order diffractive microstructure (2), and an intermediate light transmissive layer (4) separating the two diffractive microstructures. The spacing (sn,n+1) between the first (1) and second (2) diffractive microstructures is small enough so that optical interferences are produced between the diffractive microstructures. A further light transmissive layer (3) covers the second diffractive microstructure (2).

Abstract: A security Device comprises a zero order diffractive microstructure (5) buried within a substrate (3). One or more further optical structures, such as 5 microlenses (1), may be formed on a surface (2) of the substrate (3). The further optical structures modify the optical characteristics of the zero order diffractive microstructure (5). Various alternatives or additional optical structures and methods of producing them are described in additional embodiments.

Abstract: The diffractive optical device (1) can be used as a security device in the fields of authentication, identification and security. It comprises a zero-order diffractive color filter (3). The diffractive color filter may consist of a microstructured high-index layer (32) embedded between two low-index layers (31, 33). A mirror layer (4) for reflecting towards the diffractive color filter (3) at least part of light transmitted through the diffractive color filter (3) are provided beneath the diffractive color filter. Thanks to the mirror layer (4), the device (1) has a much higher reflected intensity and much more complex spectra than prior-art diffractive color filters.