Abstract: The present invention provides a process for producing a layer of a crystalline material comprising a perovskite or a hexahalometallate, which process comprises: (i) exposing a substrate to a vapour comprising a first precursor compound in a first chamber to produce a layer of the first precursor compound on the substrate; and (ii) exposing the layer of the first precursor compound to a vapour comprising a second precursor compound in a second chamber to produce the layer of a crystalline material, wherein the pressure in the second chamber is above high vacuum. The invention also provides a process for producing a layer of a crystalline material comprising a perovskite or a hexahalometallate, which process comprises exposing a layer of a first precursor compound on a substrate to a vapour comprising a second precursor compound in a chamber to produce the layer of a crystalline material, wherein the pressure in the chamber is greater than high vacuum and less than atmospheric pressure.

Abstract: The present invention provides a process for producing a layer of a crystalline material comprising a perovskite or a hexahalometallate, which process comprises: (i) exposing a substrate to a vapour comprising a first precursor compound in a first chamber to produce a layer of the first precursor compound on the substrate; and (ii) exposing the layer of the first precursor compound to a vapour comprising a second precursor compound in a second chamber to produce the layer of a crystalline material, wherein the pressure in the second chamber is above high vacuum. The invention also provides a process for producing a layer of a crystalline material comprising a perovskite or a hexahalometallate, which process comprises exposing a layer of a first precursor compound on a substrate to a vapour comprising a second precursor compound in a chamber to produce the layer of a crystalline material, wherein the pressure in the chamber is greater than high vacuum and less than atmospheric pressure.

Abstract: A multiple stage orbital delivery vehicle that uses tractor propulsion to launch the vehicle into space. Only the upper stage of the vehicle includes an engine and avionics allowing the lower stages to be only liquid propellant tanks that may be dumped when empty. The liquid propellant may be either monopropellant or bi-propellant. The upper stage may include multiple nozzles that burn the propellant. Alternatively, the upper stage may include an aerospike engine instead of nozzles. The multiple stage orbital delivery vehicle may be air launched from an airborne aircraft or may be launched from the ground.

Abstract: A multiple stage orbital delivery vehicle that uses tractor propulsion to launch the vehicle into space. Only the upper stage of the vehicle includes an engine and avionics allowing the lower stages to be only liquid propellant tanks that may be dumped when empty. The liquid propellant may be either monopropellant or bi-propellant. The upper stage may include multiple nozzles that burn the propellant. Alternatively, the upper stage may include an aerospike engine instead of nozzles. The multiple stage orbital delivery vehicle may be air launched from an airborne aircraft or may be launched from the ground.

Abstract: A multiple stage orbital delivery vehicle that uses tractor propulsion to launch the vehicle into space. Only the upper stage of the vehicle includes an engine and avionics allowing the lower stages to be only liquid propellant tanks that may be dumped when empty. The liquid propellant may be either monopropellant or bi-propellant. The upper stage may include multiple nozzles that burn the propellant. Alternatively, the upper stage may include an aerospike engine instead of nozzles. The multiple stage orbital delivery vehicle may be air launched from an airborne aircraft or may be launched from the ground.

Abstract: A liquid crystal cell (5) comprises a layer (4) of cholesteric liquid crystal material; and a retarder (3) disposed in an optical path through the layer (4) of cholesteric liquid crystal material. The cholesteric liquid crystal material is switchable between a first state in which it cooperates with the retarder (3) to provide a first viewing angle range and a second state in which it cooperates with the retarder (3) to provide a second viewing angle range which is smaller than the first viewing angle range. The pitch of the cholesteric liquid crystal material is greater than an intended wavelength of operation of the liquid crystal cell divided by the average refractive index of the liquid crystal material. The liquid crystal cell may be used as a Viewing Angle Restriction (VAR) element, to enable another component, such as a display panel (6), to be operated in either a wide viewing mode or a narrow viewing mode.

Abstract: A liquid crystal cell (5) comprises a layer (4) of cholesteric liquid crystal material; and a retarder (3) disposed in an optical path through the layer (4) of cholesteric liquid crystal material. The cholesteric liquid crystal material is switchable between a first state in which it cooperates with the retarder (3) to provide a first viewing angle range and a second state in which it cooperates with the retarder (3) to provide a second viewing angle range which is smaller than the first viewing angle range. The pitch of the cholesteric liquid crystal material is greater than an intended wavelength of operation of the liquid crystal cell divided by the average refractive index of the liquid crystal material. The liquid crystal cell may be used as a Viewing Angle Restriction (VAR) element, to enable another component, such as a display panel (6), to be operated in either a wide viewing mode or a narrow viewing mode.

Abstract: An active boresight drift measurement and calibration apparatus utilizing a predetermined number of interferometer units to measure the distances between themselves, the target tracking unit and the beam direction sensing unit. The interferometer units provide the initial alignment reference and by periodic repeat measurements provides distance change data to establish boresight alignment drift correction angles.