Abstract: A distributed Bragg reflection pass-band filter in an optical fiber waveguide is provided by grating elements arranged to provide improved flatness of reflection pass-band, a high rate of roll-off, and reduced amplitude side-bands by the use of chirp and apodisation profiles that are related such that the square of the coupling coefficient is substantially proportional to the rate of change of chirp.

Abstract: An air powered water display nozzle unit which has an adjustable nozzle coupled to a housing by a support plate and a plurality of springs.

Abstract: An air powered water display nozzle unit which has an adjustable nozzle coupled to a housing by a support plate and a plurality of springs.

Abstract: A liquid display that has a plurality of adjacent parallel tubes filled with a fluid and connected to a source of air that introduces bubbles into the tubes, so that the combination of bubbles form a word, or another recognizable graphic display. Each tube has a valve connected to the air supply, that controls the duration and flowrate of air injected into the tube so that a single bubble is formed within the tube. The valves are connected to a computer that opens and closes each valve to produce a pattern of bubbles in accordance with a computer program within the computer. The program creates a combination of bubbles that together depict a legible design or display.

Abstract: A water device that can display predetermined patterns that form letters, numbers, pictures or other visually apparent figures. The water display has a shallow pool of water with a flat bottom surface, that has a plurality of holes spaced apart in a grid like fashion. The holes are connected to a source of air that introduces bubbles into the pool. The air exits the water in such a manner as to leave a visually distinguishable mark or impression in the pool. The bubbles are combined and patterned into an identifiable figure such as a word or a set of numbers. Each hole has a solenoid valve that allows air to flow into the pool when the solenoid is energized. The valves are connected to a computer that selects which holes are to release air and when the bubbles are to be released. The actuation of the valves can be selected and sequenced in accordance with the operating instructions of a computer program, that produce a pattern of bubbles to create the desired form on the surface of the pool.

Abstract: A non-contacting method of measuring the electrical resistance per unit length of a filament, such as a carbon-coated optical fibre, makes the filament the inner conductor of a co-axial transmission line and measures a propagation characteristic of that line. The transmission line may be divided into seven sections, with a signal injected on the second section, and a comparison of the resulting signals appearing on the fourth and sixth sections being used in a feedback loop to control the injected signal frequency in such a way as to hold constant either the relative amplitudes or the relative phases of the signals appearing at the fourth and sixth sections.

Abstract: A ribbed structure (60a), co-operating with an unribbed surface of a coupling element 64, is employed to introduce microbending in an optical fibre (51) intermediate its two ends with a periodicity which couples the fundamental bound mode of the fibre into a cladding mode from which optical power is tapped into the optical coupling element (64) provided with a conical reflecting surface (63a) for collimating the extracted light. Light injection is achieved by a reciprocal process using a ribbed structure (60b) and a conical reflecting surface 63b.

Abstract: A scanning keratometer for the rapid and accurate measurement and mapping of the corneal curvature is disclosed. The keratometer has a monochromatic light source directing light to a scanner, preferably controlled by a microcomputer. The scanner directs the light to a holographic element functioning as a lens which in turn focuses the light to a fixed focal point forward of the holographic element independent of the area of the holographic element being illuminated. The subject's eye is position with respect to the fixed focal point so that a part of the light incident to the eye is reflected from the surface thereof again passing through the holographic element, to be deflected from the main optical axis of the system to a suitable area sensor. Assuming the subject's eye is properly positioned and the cornea surface matches the shape of an ideal cornea, the light incident to the cornea will be reflected in the same direction as the incident light, ultimately impinging on the center of the sensor.

Abstract: A device comprising a capacitive transducer comprised of a fixed member comprising first and second axially separated equal diameter metallic electrode rings and a movable member comprised of a thin walled metallic cylinder separated from the fixed member by an annular gap such that said movable member capacitively couples said first and second rings of the fixed member. The first ring of the fixed member is comprised of a continuous metallic ring glued onto an insulating supporting means, and the second ring is comprised of four thin metal foil electrodes separated by four equi-width narrow gaps spaced at angular intervals of 90.degree. and glued onto an insulating supporting means. The first electrode ring of the fixed member is electrically connected to an alternating current power source and each pair of diametrically opposed electrodes of the second ring of the fixed member are electrically connected to a position control loop circuit.

Abstract: This invention applies to a magnetic bearing comprising stator and rotor members positioned coaxially with each other in the same plane with an annular gap therebetween, and electrical coils located in pairs on each axis in the plane. According to the invention, the control of the energization of the coils is performed by detecting, for each axis, the relative position error between the stator and the rotor members of the magnetic bearing from a reference position and generating a first or a second control signal depending on whether the position error is positive or negative. The first control signal is applied to a first electronic circuit including the electrical coil at one end of said axis and the second control signal is applied to a second electronic circuit including the electrical coil at the other end of the axis. In this way, only that coil is energized which is located where the gap between the stator and rotor members is smaller, whereby the magnetic flux there is reduced.

Abstract: A magnetic suspension device comprising an annular stator surrounded by a coaxial annular rotor with an annular gap therebetween. The rotor comprises an axial ring-like permanent magnet for creating the suspension magnetic field. The stator comprises a ring-like U-shaped section of a magnetic material with an axial ring portion and a pair of parallel radial annular portions, the axial ring portion including segmental coils for producing positioning control magnetic fluxes for radial positioning of the rotor relative to the stator. The mode of construction of the stator considerably facilitates the fabrication and assembly of the device and provides a more efficient operation than the known devices.