Abstract: An optical modulator includes an optical input; an optical output; at least one optical path connecting the optical input and output; and an electrode structure for selectively changing the optical characteristic of a part of the at least one optical path in response to a control signal such as to modulate light passing along the optical path. The optical path further includes a structure which slows the passage of light along the part of the optical path to enhance the modulation effect of the modulator for a given length of optical path. Preferably the structure comprises a sequence of coupled resonator structures in which each resonator structure is defined by a pair of partially reflecting planes which define an optical resonator cavity within the optical parts.

Abstract: The performance of a microwave antenna is improved by incorporating a fine wire dielectric material which has a dielectric constant ∈ of less than unity at microwave frequencies. The effect of the dielectric material is to refract microwaves so that the antenna appears to have a larger aperture than that of its physical size. Furthermore, by selecting the transmission cut off frequency of the dielectric material, two antenna elements which are intended to operate within different frequency bands can be mounted one behind the other.

Abstract: The present invention provides a wavelength selective optical filter device (240) for receiving input radiation and outputting corresponding filtered output radiation, characterized in that the filter device (240) includes a plurality of at least partially mutually coupled Fabry-Perot optical resonators (330, 340, 360; 360, 400, 430) for filtering the input radiation to generate the output radiation, the filter device (240) being tunable from a first radiation wavelength to a second radiation wavelength by mutually detuning the resonators in a period where the resonators are being retuned from the first wavelength (&lgr;1) to the second wavelength (&lgr;2) so that the filter device (240) is substantially in a non-responsive state during the period. The resonators incorporate freely suspended mirrors (360, 430) which are electrostatically actuated to affect tuning of the resonators (330, 340, 360; 360, 400, 430).

Abstract: The present invention provides a wavelength selective optical filter device (240) for receiving input radiation and outputting corresponding filtered output radiation, characterised in that the filter device (240) includes a plurality of at least partially mutually coupled Fabry-Perot optical resonators (330, 340, 360; 360, 400, 430) for filtering the input radiation to generate the output radiation, the filter device (240) being tunable from a first radiation wavelength to a second radiation wavelength by mutually detuning the resonators in a period where the resonators are being returned from the first wavelength (&lgr;1) to the second wavelength (&lgr;2) so that the filter device (240) is substantially in a non-responsive state during the period. The resonators incorporate freely suspended mirrors (360, 430) which are electrostatically actuated to affect tuning of the resonators (330, 340, 360; 360, 400, 430).

Abstract: A hydrogen replenishment system for providing hydrogen to a hydrogen-receiving apparatus, the system comprising (i) an electrolytic cell for providing source hydrogen; (ii) a compressor means for providing outlet hydrogen at an outlet pressure; (iii) means for feeding the source hydrogen to the compressor means; (iv) means for feeding the outlet hydrogen to the hydrogen-receiving apparatus; (v) central processing unit means for controlling the cell and the compressor; and (vi) user activation means for operably activating the central processing unit means. The invention provides a practical user interface in the treatment of data provided, computed, measured and stored, to offer a convenient, essentially self-contained, hydrogen fuel replenishment system for vehicles based on water electrolysis. The apparatus has virtually no stored hydrogen and provides pressurized hydrogen on the demand of a user.

Abstract: The present invention provides a wavelength selective optical filter device (240) for receiving input radiation and outputting corresponding filtered output radiation, characterized in that the filter device (240) includes a plurality of at least partially mutually coupled Fabry-Perot optical resonators (330, 340, 360; 360, 400, 430) for filtering the input radiation to generate the output radiation, the filter device (240) being tunable from a first radiation wavelength to a second radiation wavelength by mutually detuning the resonators in a period where the resonators are being retuned from the first wavelength (&lgr;1) to the second wavelength (&lgr;2) so that the filter device (240) is substantially in a non-responsive state during the period. The resonators incorporate freely suspended mirrors (360, 430) which are electrostatically actuated to affect tuning of the resonators (330, 340, 360; 360, 400, 430).

Abstract: A sensor package for proximity detectors adapted for use with materials having a significant angle of repose. The sensor package includes a hollow housing defining a cylindrical main body adapted to house proximity detection circuitry and a non-planar tip disposed on one end of the housing adjacent the main body. The tip portion is preferably tapered in its diameter from a dimension generally equal to the diameter of the main body to a dimension less than the diameter of the main body. The tip is adapted to house a sensing element electrically coupled to the proximity detection circuitry and disposed on an inner bottom surface of the tip portion. Preferably, the taper of the tip is selected to substantially match the angle of repose of the materials to be sensed, and may take on a wide variety of shapes including cone, frustum, pyramid, round and hemispherical.

Abstract: An improved process for providing hydrogen from an electrolytic cell having an anolyte solution having an anolyte liquid level; a catholyte solution having a catholyte liquid level; generating oxygen at an oxygen pressure above the anolyte level; generating hydrogen at a hydrogen pressure above the catholyte level; the improvement comprising detecting at least one of the anolyte and the catholyte liquid levels as anolyte level and catholyte level data; feeding the level data to central processing means; determining the pressure differential between the levels from the level data, and pressure adjustment data by the central processing means; and providing the adjustment data to pressure control means to maintain the pressure differential within a selected range. The process offers a low cost method of controlling the pressure differential to within 2 cm WC of a set point.

Abstract: An apparatus for verifying the installation and alignment of a moveable member of an object, such as, for example, the door of a vehicle. The final closing velocity of the moveable member is measured after the member is moved from an initial first position (e.g. opened) toward a second position (e.g. closed). The apparatus controllably engages and moves the movable member from its initial first position toward the second position by temporarily applying controlled force to the movable member. The apparatus determines the orientation of the object or of the moveable member and also includes a series of platforms that may be translated, rotated and raised so that moving the movable member of the object with the controlled force occurs when the moveable member is in a predetermined spatial position and orientation. The apparatus further determines the distance to the movable member so that the final closing velocity of the moveable member may be determined.

Abstract: An optical device comprising an optical waveguide (13) on a substrate (11) which over part of its length forms one of a stack (15) of coupled optical waveguide sections of the same length, the stack being of a length such that a light wave of predetermined frequency propagating along the waveguide (13) to enter the stack (15) at one end thereof produces light waves at the other end of the stack which are substantially in phase adjacent each waveguide section. The device finds particular application for coupling light from a substrate waveguide into another waveguide, e.g. an optical fibre (27), off the substrate (11).

Abstract: An optical device comprising a length of optical waveguide (1) having incorporated therein an extended sequence of coupled single resonator structures (9) so as to form an optical slow wave structure. The sequence of resonator structures is suitably formed by a Bragg diffraction grating pattern (7) extending along the waveguide.

Abstract: An optical sensor includes a resonant mirror device 1, and a prism 2 disposed adjacent the device for coupling a beam of light into the device 1. The device 1 and the prism 2 are mounted on a rotatable platform. A beam of light is produced by He-Ne laser 3 and is linearly polarized with equal TE and TM components by a polarizer 4 arranged at 45.degree. to TE and TM axis. A lens 6 is arranged in the path of the linearly polarized beam of light for focussing the beam of light onto the device thereby providing simultaneously a range of angles of incidence at which the beam of light can be coupled into said device. The platform on which the device 1 and the prism 2 are mounted, is rotated to a position, at which the angle of incidence of beam of light coupled into the device is such that a resonance is excited in said device for at least one of said components. The beam of light reflected from the device is passed through an analyser 11 arranged at 90.degree. to the polarizer 4.

Abstract: This invention describes a technique for improving the sensitivity of a resonant mirror sensor which has particular applications in areas involving sensing at an interface such as immunosensing using immobilized antibodies. By the introduction of a Bragg grating structure in the sensor, there is produced enhanced dispersion and hence enhanced sensitivity in the region close to the band edge. This improves the detection limit of the sensor without changing the composition or involving the sensor size and allows more sensitive operation at reduced incident angles.

Abstract: An optical fibre coupling device comprises a mount 11 supporting an optical fibre waveguide having at a fibre end a surface of the fibre core 2 material which is surrounded by a body 3 of cladding material. At the core end a circular symmetric phase plate 7 is centered about the core 2 such that the light from a laser 1 entering or leaving the waveguide experiences a predetermined phase change. The phase change can act to reduce an optical coupling loss which occurs when the device is in use.

Abstract: Non-stick protection can be given to the surfaces of thermoplastic material which has a tendency to become stuck to other thermoplastic surfaces during storage, especially during the heat of the summer months. By placing a film of (1) a salt selected from (a) a hydroxy alkyl sulfonate salt and (b) and alkyl sulfonate salt, and (2) an alkyl sulfate salt on the surface of the thermoplastic, sticking can be reduced or totally prevented.

Abstract: An optical assay apparatus of the type comprising an optic waveguide and a coating sensitized to a specific assay species. The light signal response of the apparatus is enhanced by coupling a resonant metallic medium to the waveguide and to the sensitized coating. To this end, a metal coated transparent buffer layer may be interposed between the waveguide and the sensitized coating. Alternatively, a metallized optically matched grating can be used in place of the buffer layer or the metallic medium can be of particulate form, with each particle having a sensitized coating.In using the optical assay apparatus, the sensitized coating is exposed to a fluid assay sample. A light beam is directed onto the sensitized coating and reflected onto a detector. The detected light is monitored for any change indicating the presence of the specific assay species in the fluid sample.

Abstract: A modulator of the type including an array of light modulating elements. To afford fast response and thus greater modulation bandwidth these elements, each comprising a pair of electrodes and a reflector, are defined in a sheet layer of electro-optic solids material. In particular, this material may be of PLZT ceramics material or of a similar ceramic having a high electro-optic coefficient (quadratic). To advantage, the electrodes may be embedded in the sheet layer. Each modulating element is aligned with and connected to a corresponding drive circuit, part of an integrated circuit structure. Conveniently, solder bumps are used to this end.Light is directed onto the array of modulating elements by an optical interface. This may comprise an array of micro-lenses which too may be aligned by solder bumps. A second reflector may be added to each modulating element, each then being optically resonant.

Abstract: A biosensor includes an optically dense body provided with a coating sensitized to a specific assay species, and an input and output coupling structure. Light signal response is enhanced by incorporating a partially reflecting, partially transmitting medium between the coupling structure and the optically dense body having a lower refractive index. The thickness of such medium is chosen so that light may be coupled by frustrated total internal reflection and to enable the medium to serve as a resonant mirror.

Abstract: Non-stick protection can be given to the surfaces of thermoplastic material which has a tendency to become stuck to other thermoplastic surfaces during storage, especially during the heat of the summer months. By placing a film of (1) a salt selected from (a) a hydroxy alkyl sulfonate salt and (b) an alkyl sulfonate salt, and (2) an alkyl sulfate salt on the surface of the thermoplastic, sticking can be reduced or totally prevented.