Abstract: In a display system light from an object (14) is deflected on to a collimator (16) and superimposed on an external view through a combiner (10) from an observing position (11). Relay optics (17) in the path of light from the object (14) has spaced apart elements (L.sub.1,L.sub.2) which produce first and second exit pupils (P.sub.1, P.sub.2). Exit pupil volumes (V.sub.1, V.sub.2) overlap to give an extended field of biocular view. The restricted field of view associated with prior art display systems is overcome since the present system provides a large field of view at the observing position (11), while system components fit within aircraft space constraints, such as windshield (19), fairing (33) and ejection line (20). Space remains available for other instrumentation, such as a second display CRT (45).

Abstract: A method of coating a substrate in a glow discharge chamber uses a source of hydrocarbon and another element. Butane and germane are used to deposit a coating of Ge.sub.x C.sub.1-x where 0<x<1 onto a germanium substrate. The substrate temperature is maintained above 400.degree. C., typically 530.degree. C., during growth to prevent inclusion of H.sub.2 in the coating. The presence of Ge in the coating allows thick, stain-free, layers to be grown. Alternatively, butane and silane may be used to deposit Si.sub.x C.sub.1-x. Varying the proportions of the hydrocarbon and germane or silane allows a variation in the value of x.A method of growing a combined layer of at least a first and a second material in glow discharge chamber. A target cathode formed on the first material, e.g., Si, Ge, W is arranged in the chamber and spaced from a substrate to be coated. Argon gas and a gas of the second material, e.g., a hydrocarbon, are admitted into the chamber and a glow discharge established.

Abstract: A method of preparing a fibrous activated carbon including the steps of carbonizing and activating cellulose fibre at temperatures between 200.degree. C. and 1000.degree. C. in an inert atmosphere, characterized in that, prior to activation, the fibre is impregnated with an impregnating material comprising, in the form of one or more compounds, boron and at least one alkali metal.

Abstract: A heterocyclically substituted ethane having a formula:R.sub.1 -Cy-CH.sub.2.CH.sub.2 -A-R.sub.2 Formula 1whereinA represents a heterocyclic ring selected from a trans 2,5 disubstituted 1,3 dioxan ring and a 2,5 disubstituted 1,3-pyrimidine ring;R.sub.1 represents an alkyl group having from 1 to 15 carbon atoms and R.sub.2 represents a group selected from hydrogen, alkyl having from 1 to 15 carbon atoms and alkoxy having from 1 to 15 carbon atoms provided that where A is a trans 2,5 disubstituted 1,3 dioxan ring R.sub.2 is alkyl; andCy represents a trans-1,4 disubstituted cyclohexane ring.

Abstract: A switched capacitor parasitic insensitive integrator comprises an operational amplifier (6), an integrating capacitor C.sub.2, a switched capacitor C, and four switches, two of even phase E1, E2 and two of odd phase 01, 02. In order to minimize the effect of capacitances (42) associated with the switches a 4-phase switching waveform is used such that E2 opens before E1, 02 opens before 01, E1 is not closed when 01 is closed and E2 is not closed when 02 is closed. A clock circuit may be used to provide the appropriate 4-phase switching waveform with a separate phase signal to each switch or a 2-phase switching waveform may be used with one phase signal to the E switches and the other phase signal to the O switches and the two switches E2, 02 biassed relative to E1, 01 such that the required differences in switching times occur.

Abstract: Novel terphenyls having a relatively high clearing point and which are suitable for use in liquid crystal materials or in the preparation of compounds for use in such material are characterized by a formula: ##STR1## wherein: R.sub.1 is selected from H, alkyl, alkoxy, alkylcarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy;R.sub.2 is selected from H, alkyl, alkoxy;X.sub.1 is selected from H and fluorine;X.sub.2 is selected from H and fluorine; and ##STR2## provided that one of X.sub.1 and X.sub.2 is fluorine. Compounds wherein ##STR3## are generally useful as liquid crystal compounds.

Abstract: A naval ground mine comprising two modules (1, 2) each having a cylindrical casing (4) containing explosive material. The modules have mating end faces (5), each provided with a spigot (6). Lips (7) on adjacent spigots form an annular projection which tapers in a radially outward direction. The two modules (1, 2) are held together by a split ring (3) having a corresponding internally tapered surface (9), which embraces this annular projection. As the ring (3) is tightened, the adjacent end faces (4, 5) are drawn tightly together. The external surface of the ring provides a smooth transition between the external surfaces of the modules, so as to minimize surface discontinuity and the possibility of detection by sonar.

Abstract: A constraint application processor is arranged to apply a linear constraint to signals from antennas. A main antenna signal is fed to constraint element multipliers and then to respective adders for subtraction from subsidiary antenna signals. Delay units delay the subsidiary signals by one clock cycle prior to subtraction. The main signal is also fed via a one cycle delay unit to a multiplier for amplification by a gain factor. Main and subsidiary outputs of the processor may be connected to an output processor for signal minimization subject to the main gain factor remaining constant. The output processor may be arranged to produce recursive signal residuals in accordance with the Widrow LMS (Least Mean Square) algorithm. This requires a processor arranged to sum main and weighted subsidiary signals, weight factors being derived from preceding data, residual and weight factors. Alternatively, a systolic array of processing cells may be employed.

Abstract: A process for producing a two element deposition coating on metals e.g. for oxidation/corrosion protection of superalloys, comprises halide transfer of the two elements in sequence from a reaction charge, the reaction charge including a significant excess of halide activator over the amount required for stoichiometric considerations. The transportation of the first element is terminated by reacting its source to exhaustion, in the course of the transport reaction or by evacuating from the reaction vessel. Preferred elements are aluminum with silicon and aluminum with chromium.

Abstract: An oronasal mask assembly means suitable for and having a quick release assembly use in conjunction with a protective helmet is described.An oronasal mask assembly means suitable for use in conjunction with a protective helmet and having a quick release mechanism, the quick release assembly having a mask retaining clip, engageable with a helmet mounted clip retaining means in the form of a pillar having an enlarged head portion, the mask retaining clip is attached to the mask via a cable length adjuster and cable.

Abstract: A detector in which a barrier region is interposed in the current path between the emitter and collector of the detector. This region is of a material having a valance band edge approximately level to that of the emitter material and an appreciably wider band gap. It thus serves to impede majority carrier current flow and as a consequence device resistance is high. When the detector is biased, the pedestal contribution to detector signal is low. The collector may be of semiconductor material of the same majority carried type as the emitter material; or may be of opposite type but dopant enriched; or it may be a Schottky metal contact. In one variant of the detector, the emitter and collector are located on opposite sides of the barrier and are of different bandgap materials. The infra red band response of this detector can be changed by reversing bias polarity. In another variant of the detector the emitter is in strip form and has a pair of bias contacts.

Abstract: The invention relates to magnetic assemblies and in particular, though not exclusively to magnets for use in mine-sweeping or ship degaussing systems.

Abstract: A remote sensor for detecting gas, vapor or aerosol comprises means to measure the change in temporal coherence of light of a selected narrow waveband when it interacts with the gas etc. The light can be provided by a laser source or spectrally filtered sun light etc. Received radiation is split in to two beams by a Fresnel biprism and then detected by a detector sensitized by a modulating reticle to interference fringes. A glass delay plate of suitable thickness is placed in the path of one of the beams such that only received radiation having a temporal coherence greater than a minimum determined by the plate thickness produces an output signal from detector. The minimum temporal coherence is set higher than the temporal coherence of the illuminating radiation. In alternative arrangements a band-pass temporal coherence filter may be used and the sensor can be made to spectrally scan the field of view by using a tunable laser or a variable center frequency band-pass optical filter.

Abstract: An alignment aid for use in installing a reference system of known type which reflects an image of an indicator mark mounted on a gun turret, back into the gun sight via a mirror mounted at the muzzle end of the gun barrel, for comparison with a reference mark on the graticule of the gunsight, thereby to indicate any angular deviation between the muzzle axis and the gunner's line of sight. The alignment aid, which is used in setting the mirror to provide initial coincidence between the indicator mark image and the reference mark, consists of a highly reflective viewing screen attachable to the turret adjacent the indicator mark, and a projection lamp attached to the gun sight so as to protect an image of the reference mark onto the screen, via the telescopic optics of the gunsight and the mirror.

Abstract: A raster image manipulator includes source and destination image data stores respectively 1024.times.1024 and 512.times.512 pixels in extent. A clock and counter are employed to increment in unit steps the destination store address at which image data from the source store is to be stored. Source store addresses from which image data are obtained are calculated from precomputed shift parameters by adders arranged for cumulative addition. The shift parameters are fractional increments in source store address corresponding to unit increments in destination store address. After designating an initial source memory address, image manipulation consists of incrementation of the destination store address in unit steps with corrresponding incrementation of the source store address in shift parameter steps. The invention is capable of applying rotation, shift and X and Y magnification to image data in the source store.

Abstract: A sealed pivot joint suitable for joining together the adjacent links of an endless belt, for example, a tank track. The joint has a bearing (10) rotatable on a pin (8), and an elastic sleeve (20) whose extremities are in sealed relationship to the pin and bearing thereby preventing the ingress of abrasive material into, and the egress of lubricant from, the bearing surface (12). The sleeve is maintained in circumferential tension by tensioning members (14, 16, 18) between the sleeve and the pin which act to prevent wrinkling of the sleeve when the pin and bearing are rotated relative to one another thereby reducing abrasive wear on the outer surface of the sleeve.

Abstract: A ram air parachute assembly adapted for deployment by use of static line suitable for use at high altitudes and high drop speeds, the parachute assembly comprising a ram air parachute 21, a pilot parachute 23, attached by a bridle line 22, and slideable square 25 to the ram air parachute, and being packed in a parachute bag 10 attachable to an aircraft by way of a static line 11.

Abstract: A ceramic evacuatable enclosure (10, 30, 42) such as a laser body is made by the following process. A first body portion (12, 41) is formed with a channel (18, 19, 20, 43, 45, 46) and second body portion (11, 31, 40) of the same ceramic material is provided. Mating surfaces are polished on the body portions (11, 12) for bonding together by thermocompression below the ceramic distortion temperature to achieve a vacuum seal. The ceramic may be alumina including 0.2 to 12% by weight of vitreous material. The thermocompression temperature may be in the range 1200.degree. C. to 1750.degree. C. Polishing is performed to a finish of from 0.01 .mu.m to 0.15 .mu.m. The body portions (11, 12) may have similar surface formations mutually aligned to provide a folded cavity (18, 19, 20) for an alumina waveguide CO.sub.2 laser.

Abstract: A layer of Cd.sub.x Hg.sub.1-x Te is grown on the surface of a substrate by decomposing alkyls of cadmium and telluride in a mercury atmosphere. The substrate is placed in a vessel containing a mercury bath with the vessel and bath at a suitable pressure and a temperature below the alkyl decomposition temperature. Hydrogen is passed through bubblers separately containing alkyls of cadmium, telluride and, if required, a dopant into the vessel. The substrate is independently heated above the temperature of the vessel so that the alkyls decompose on the substrate. The substrate may be CdTe, a II-VI compound or mixed II-VI alloy. The alkyls may be dimethyl cadmium, diethyl cadmium, dipropyl cadmium, dimethyl telluride, diethyl telluride, dipropyl telluride, dibutyl telluride etc., or hydrogen substituted tellurium alkyls such as hydrogen ethyl telluride etc.

Abstract: A bridge span is provided with coupling means enabling two spans to be carried jointly in pickaback fashion on an inversion-launch bridgelayer and launched separately therefrom without exposure of personnel.The launch system requires no modification to the bridgelayer.