Abstract: An interference filter, also referred to as a notch filter, of the type which reflects a certain wavelength range while letting pass over wavelengths bands of a range is disclosed. The filter is designed for operation in the visual and infra-red regions of the electromagnetic spectrum and in the disclosure the uniform layer pairs of material are such that the optical thickness of each layer of the or each layer pair deposited on a plane light-transmitting substrate is a non quarter-wave unequal thickness with respect to its complementary layer. Each layer pair has an overall optical thickness adding up to in total a half-wave thickness.

Abstract: A current probe is provided which comprises a handle and a ring of magnetisable material for positioning around an electrical conductor, the ring being split into two portions one being fixed relative to the handle and the other being slidable therewithin between a position in which the ring is closed and a position in which the ring is open. The line of split of the ring is at an angle from the line of sliding movement of the linearly slidable portion. Damping is provided to prevent the slidable portion of the ring from too rapidly moving from a position in which the ring is open to a position in which the ring is closed.

Abstract: High phosphorus polyphosphides, namely MP.sub.x, where M is an alkali metal (Li, Na, K, Rb, and Cs) or metals mimicking the bonding behavior of an alkali metal, and x=7 to 15 or very much greater than 15 (new forms of phosphorus) are useful semiconducutors in their crystalline, polycrystalline and amorphous forms (boules and films). MP.sub.15 appears to have the best properties and KP.sub.15 is the easier to synthesize. P may include other pnictides as well as other trivalent atomic species. Resistance lowering may be accomplished by doping with Ni, Fe, Cr, and other metals having occupied d or f outer electronic levels; or by incorporation of As and other pnictides. Top contacts forming junction devices doped with Ni and employing Ni as a back contact comprise Cu, Al, Mg, Ni, Au, Ag, and Ti. Photovoltaic, photoresistive, and photoluminescent devices are also disclosed. All semiconductor applications appear feasible.

Abstract: High phosphorus polyphosphides, namely MP.sub.x, where M is an alkali metal (Li, Na, K, Rb, and Cs) or metals mimicking the bonding behavior of an alkali metal, and x=7 to 15 or very much greater than 15 (new forms of phosphorus) are useful semiconductors in their crystalline, polycrystalline and amorphous forms (boules and films). MP.sub.15 appears to have the best properties and KP.sub.15 is the easier to synthesize. P may include other pnictides as well as other trivalent atomic species. Resistance lowering may be accomplished by doping with Ni, Fe, Cr, and other metals having occupied d or f outer electronic levels; or by incorporation of As and other pnictides. Top contacts forming junction devices doped with Ni and employing Ni as a back contact comprise Cu, Al, Mg, Ni, Au, Ag, and Ti. Photovoltaic, photoresistive, and photoluminescent devices are also disclosed. All semiconductor applications appear feasible.

Abstract: The present invention provides a decorative lamp for displaying three dimensional works of art, photographs, and the like. A frustoconical lampshade formed from a non-translucent material has an opening cut from it to provide a viewing aperture. A first translucent panel having an art motif or other suitable design on it is affixed to the inside of the lampshade and covers the opening. The curvature of the first panel corresponds to the curvature of the lampshade. Additional translucent panels containing artwork complimenting that on the first panel are mounted concentrically within the lampshade at predetermined distances apart from the first panel to create a three dimensional effect. The inner panels are configured in a frustoconical shape to conform to the general configuration of a standard lampshade.

Abstract: An infra-red optical system, such as an afocal telescope, having a beam-splitter plate located in a beam position having one valve of numerical aperture and tilted with respect to the optical axis has a single compensating plate located in a beam position having a different value of numerical aperture and tilted differently with respect to the optical axis so as to compensate for aberrations introduced by the tilted beam-splitter plate. The beam-splitter and compensating plates are preferably tilted about respective first and second axes orthogonal to the optical axis and lying on mutually orthogonal planes.

Abstract: The present invention provides a method and apparatus for continuous delivery of a liquid from individual liquid holding containers to a common discharge outlet. A bulk package is adapted to removably store a plurality of sealed liquid containers in predetermined positions within the package. The top surface of the package defines a plurality of openings for exposing the tops of the individual containers stored within the package. A removable lid includes a plurality of sharp discharge outlets or hollow spikes corresponding in number and disposed in alignment with the openings defined on the top surface of the package. The sharp discharge outlets extend from the lower surface of the lid, and are employed to puncture the openings in the individual containers stored within the package. The lid itself defines a hollow chamber providing a reservoir for receiving the flow of liquid from the individual containers.

Abstract: The invention is concerned with a weapon aiming system for use in a fire control system such as those used in a military tank. The aiming system includes a linkage which connects a mirror with an angularly movable weapon (a gun). Upon angular movement of the gun its movement is transferred through the linkage to the mirror. The ratio of angular movement imparted between the weapon and the mirror is 2:1. Two exemplary embodiments are described and in each the linkage includes two parallelogram linkage sets each set comprising a connecting link joining two parallel arms. The system also includes a slider crank positioned in the system to form a first side of a variable triangle of links in the system. The second side of the variable triangle is formed by one parallel arm of one of the parallelogram linkage sets and the third side is formed by at least part of the connecting link.

Abstract: The present invention is directed to a method and apparatus for teaching fractions to school age children. The invention provides an instrument having a base with at least two aligned scales of corresponding numerical indicia subdivided into different fractional units, as for example halves, thirds, quarters, sixths, and eighths. The base defines a space or gap between the different fractional scales so that a writing media, such as a piece of paper, may be inserted between the scales and moved either horizontally or vertically relative to one or more of the scales. The instrument provides an easy manner for a student to compare fractional units of the same integer and also to add and subtract both fractions and mixed numbers. In the preferred embodiment of the invention, the base of the instrument may be transparent so that all fractional scales are visible to the student simultaneously.

Abstract: The present invention provides a modular electrical power block assembly including a plurality of ports for receiving individual modular circuits. The power block assembly includes seven separate electrical conductors, three of which are hot, two of which are neutral and two of which are ground, for providing three separate and independent circuits. The hot wire of one of the circuits is advantageously separated from the hot wires of the remaining two circuits by two grounds and two neutrals and one circuit may be shielded to prevent penetration of electro-magnetic interference from the other circuits. Individual circuit modules are adapted to be received within individual ports of the power block for selectively completing one or more of the three independent circuits provided by the power block assembly. The contacts extending from the individual circuit modules are arranged to engage only preselected wires within the power block assembly for completing a predetermined circuit.

Abstract: A display system which can be used inside a vehicle such as a military tank to monitor at least part of the surrounding panorama. The display system has a display generator and an optical system for viewing the display. Electronic means are provided to predistort the display to compensate for distortion present in the optical system. The system includes individual display units mounted side-by-side, each having a respective television camera associated therewith so that a substantially continuous picture of at least part of the surrounding panorama can be reconstructed and viewed by an observer without any apparent mismatch between adjacent displays.

Abstract: The invention relates to knee joint endoprosthesis consisting of a femur part provided with two skid surfaces leaving a free space between each other, said surfaces being connected with each other in front and having their curvature increasing from the front towards the rear and being curved also on planes perpendicular to said curvature; a tibia part having two surfaces on which the skid surfaces ride in a sliding manner, with an elevation being disposed between said two surfaces; and of artificial connecting means for keeping the two parts of the prosthesis together.

Abstract: Accurate metered amounts of Pnictide.sub.4 species are delivered via an argon carrier gas into an evacuated sputtering deposition chamber. The pnictide is maintained at a high temperature in a tall column by means of a constant temperature oil bath. An inert gas, such as argon, is passed through the column of Pnictide and the Pnictide.sub.4 enriched carrier gas delivered to the vacuum chamber. Films of pnictide, polypnictide, and other pnictide compounds may be deposited for semiconductor, thin film transistors, and other applications including insulation and passivation, particularly on III-V semiconductors. The local order of the deposited films may be controlled by varying the amount of energy delivered to the surface of the substrate, which is a function of its temperature, the RF power used, and the amount of excess P.sub.4 supplied. The pnictides used in the invention may include phosphorus, arsenic and antimony. Phosphorous and KP.sub.15, and KP.sub.x wherein x ranges from 15 to infinity are discussed.

Abstract: A tooth cleaning tablet which is self-foaming and self-cleansing on chewing and which includes a self-foaming effervescent couple composition which enables the tablet readily to form a foam on chewing without the need for agitation with a toothbrush and also without the need to suck air into the mouth, the self-foaming effervescent couple composition comprising a carboxylic acid, an alkali metal carbonate salt, a wetting agent such as sodium lauryl sulphate, and a swelling agent such as zanthan gum.

Abstract: In an anti-skid device for motor vehicles with a plurality of resilient spreading arms (5) distributed over the circumference of a support (1) which can be set into a revolving motion for chain strands (3) forming anti-skid means, the spreading arms (5) are formed by compression springs (8) which are precompressed by connecting elements (13) which connect the chain strands (3) to the support (1).

Abstract: A fore line trap is located before the forepump in a vacuum system. The trap utilizes a cracker, which may be a heated filament or a plasma, and cold walls. The cracker cracks pnictide gas species such as P.sub.4 into other species such as P.sub.2 which have a higher sticking co-efficient. The pnictides are deposited on the cold walls. The cold walls preferably comprise a sleeve which may be removed from the trap and replaced by a clean one.

Abstract: A construction of girder and joist supports for framed concrete slabs wherein continuous metal decking and standard joists are used and wherein rigid connections are established between the concrete and the girders by means of shear connectors which are embedded in the concrete and connected to extensions fixed to the tops of the girders.

Abstract: Thin film field effect transistors utilize MP.sub.x as the active switched semiconductor where M is at least one alkali metal, P is at least one pnictide, and x ranges from 15 to infinity. Phosphorus is preferred as the dominant pnictide and potassium is preferred as the dominant alkali metal. The local order of the semiconductors may vary from an all parallel pentagonal tube-like structure to a layer-like puckered sheet structure. The all parallel pentagonal tube structure is preferred. Metal insulated semiconductor (MISFETS) and metal semiconductor (MESFETS) field effect transistors are disclosed. The semiconductor is preferably doped with up to approximately 1/2% nickel, iron, or chromium, to reduce the density of defect levels in the bandgap without increasing the conductivity. The semiconductors may be doped with 1/2-1% of the same metals to increase conductivity so as to provide normally ON devices.

Abstract: An apochromatic catadioptric lens is provided which can operate in the 3 to 5 and the 8 to 12 micron wavebands. The lens comprises a primary mirror having an opening and a Mangin secondary mirror for directing light of the required wavebands through the opening. In the light paths between the primary mirror and Mangin secondary mirror are a pair of refracting lens elements of optically transmissive materials different from each other and from that of the Mangin secondary mirror. Preferably, the Mangin secondary mirror is of germanium, the refracting lens element of the pair nearer the Mangin secondary mirror is of zinc sulphide and the refracting lens element of the pair further from the Mangin secondary mirror is of zinc selenide. The invention also extends to an afocal telescope of non-Galilean form incorporating such a lens.