Abstract: This invention relates to the assembly of optical microsystems by passive alignment techniques. A technique is described for the fabrication of optimised structural elements with rounded edges (continuous-relief) for providing means for integration with active or passive micro-optical elements, optical fibres or with other microsystem components. The use of replication technology for producing the microstructures on individual devices or on complete wafers allows production in high volume and at a low cost per piece. The shape of the microstructures offers similar functionality for alignment purposes as etched silicon V-grooves, but the fabrication process gives more degrees of freedom for the layout design. A particular feature is the possibility to fabricate circular alignment grooves for the vertical alignment of optical fibres to Vertical Cavity (VCSEL) laser structures.

Abstract: A passive infrared intrusion detector for the detection of infrared body radiation includes a sabotage detector, in particular for detecting spraying of the entrance window of the intrusion detector. The sabotage detector includes a light source, a corresponding light sensor, and an optical diffraction grating structure on the outside of the entrance window. The light source and the light sensor can be on the same or on opposite sides of the entrance window. By first- or higher-order diffraction, light from the light source is focused onto the sensor, and a resulting electrical signal from the sensor is evaluated by an evaluation circuit. In case of sabotage, the focusing effect of the optical diffraction grating structure vanishes, so that the light intensity at the detector is reduced. The drop in light intensity triggers a sabotage alarm signal.

Abstract: A recording blank, composed of at least one diffraction grating substrate, such as nickel, covered with a layer of photoresist is used to produce an embossing master by exposing the photoresist to picture information composed of respective white and non-white manifesting regions; developing the exposed photoresist to reveal the grating portions underlying solely the white manifesting regions; electroplating and/or etching the revealed portions to level and obliterate the revealed grating portions, and then removing the remainder of the photoresist.

Abstract: The disclosed filter provides (1) a high contrast between black and white together with a substantially neutral black and/or (2) a gray-scale color (wavelength) characteristic which is substantially independent of luminosity, and is preferably neutral. Neutral black is achieved when two superimposed, crossed, sine-wave gratings embossed in plastic have different depths which are selected to provide a zero-diffraction-order-light transmittance wavelength selectivity characteristic for any one of the phase gratings which exhibits a minimum zero-diffraction-order-light transmittance at desired different wavelengths in the visible spectrum. A gray scale is achieved by mixing black-manifesting subareas with white-manifesting subareas.

Abstract: Pulse width modulated surface relief phase holograms are produced on a substrate by developing a holographic interference pattern recorded on a photoresist deposited on the surface of said substrate as an amplitude modulated sinusoidal surface relief pattern so as to expose the surface of said substrate as a function of the intensity of said interference pattern, uniformly etching said substrate and removing said photoresist leaving a pulse width modulated, substantially two-level rectangular wave diffraction grating. Focused image holograms produced by this method on hard durable substrates may be used as masters for replicating said holograms in a suitable recording medium.

Abstract: A surface relief pattern, e.g. a surface relief hologram, is substantially linearly transferred to a hard durable substrate, capable of being used as a medium for permanent storage of the pattern or as a master for replicating the hologram, from a photoresist coated on the substrate, by exposing the photoresist and the substrate to a photoresist developer bath and a chemical bath capable of etching the substrate at a rate substantially proportional to the development rate of the photoresist. This technique allows the transfer of surface relief patterns with dimensions on the order of one micron or less, and is applicable to the formation of surface relief holographic patterns in permanent media for archival storage and to making master surface relief holograms.