Abstract: A rotor of a gas turbine having two adjacent rotor discs, on each of which moving blades are fastened, an annular rotor component being arranged between the rotor discs and having at its opposite ends circumferential annular grooves, in each of which a circumferential fastening projection on the respective rotor disc engages. When the rotor is stationary a first outer flank of the first annular groove rests under pressure against a first outer flank of the first fastening projection and there is play between a first inner flank of the first annular groove and a first inner flank of the first fastening projection.

Abstract: A method is disclosed for addressing a matrix-array type liquid crystal layer. The cell has a plurality of pixels which are defined by regions of overlap between two sets of electrodes which sandwich a liquid crystal layer, each pixel having two states. The response time for switching between the two states is dependent upon the voltage across the liquid crystal layer, with a minimum occurring at a particular voltage. The method includes applying a strobe waveform to a selected member of a first set of the electrodes while a data waveform is applied to each member of the second set of electrodes. A waveform for switching a pixel defined by the selected member comprises a switching pulse of a given voltage magnitude and given duration. A waveform for not switching a pixel defined by the selected member comprises a non-switching pulse of a voltage magnitude greater than the given voltage magnitude of the switching pulse and a duration less than the given duration of the switching pulse.

Abstract: The working temperature range of a 2 .mu.m thick negative dielectric anisotropy smectic C phase filled ferroelectric liquid crystal cell that is addressed on a matrix basis with balanced bipolar data pulses and unipolar strobe pulses is extended by the inclusion of a temperature sensor to use the temperature of the cell to control the magnitudes of the data and strobe pulse waveforms and to provide, at least at high temperatures, a stabilization waveform with a frequency twice the fundamental frequency of the data pulse waveform.

Abstract: A method of addressing a matrix addressed ferroelectric liquid crystal cell is described that uses parallel entry of balanced bipolar data pulses on one set of electrodes to co-operate with serial entry of unipolar strobe pulses on the other set of electrodes. The polarity of the strobe pulses is periodically reversed to maintain charge balance in the long term.

Abstract: Optical four wave mixing is provided by interfering two waves on a liquid crystal layer (1) temperature stabilized just beneath its nematic/isotropic phase change transition temperature. The liquid crystal incorporates a guest dye to absorb the light producing a holographic thermal image which is accompanied by a holographic phase image. Once this phase image starts to build up it is illuminated with a `third wave` of light that is not absorbed so as to produce the required holographically diffracted `fourth wave`.

Abstract: A thermal image is created in a thermostatically controlled liquid crystal cell (4) containing a two-frequency nematic or cholesteric (3). This is addressed with an alternating potential whose frequency can be swept through the cross-over frequency. By appropriate choice of frequency within this range the thermal image is converted to a phase image which in its turn is converted to a contrast image in conventional manner.

Abstract: Optical four wave mixing is provided by interfering two waves on a liquid crystal layer (1) temperature stabilized just beneath its nematic/isotropic phase change transition temperature. The liquid crystal incorporates a guest dye to absorb the light producing a holographic thermal image which is accompanied by a holographic phase image. Illumination of this phase image with a `third wave` of different wavelength is then used to produce the required holographically diffracted `fourth wave`.

Abstract: The array of electrodes of an active silicon backed matrix addressed liquid crystal cell incorporating a black guest dye arranged in groups whose individual members exhibit contrasting colors, typically, red, blue, green and optionally yellow, whereby a polychromatic image can be displayed.

Abstract: A coherent light image generator for signal processing such as image correlation directs laser light onto a specularly reflecting matrix addressed dyed nematic liquid crystal display device having a liquid crystal layer sandwiched between a transparent electroded front plate and an active single crystal silicon wafer incorporating NMOS circuitry.

Abstract: A curtailed drive scheme for a matrix array liquid crystal display cell in which the field developed across each picture element is maintained for only a fraction of the time interval between consecutive addressings. This reduces the effects of differences in time constants across the display for addressing schemes in which the average time constant is short compared with this time interval between consecutive addressings.

Abstract: A liquid crystal display device has a tandem arrangement of two cells. The rear cell is an active silicon matrix backed dyed nematic cell with 180.degree. twist cell affording the possibility of grey scale representations. The front cell is a dyed nematic cell oriented to act as a variable density polarizer to absorb the weakly absorbed plane of the rear cell. Control of this absorption is used to optimize the contrast perception in the rear cell under different ambient lighting conditions.