Abstract: An optical parametric oscillator (OPO) comprises a resonant cavity for signal light, and an optically non-linear medium disposed in the resonant cavity for converting pump light into the signal light, wherein the resonant cavity is arranged so that in operation signal light is repeatedly output from and returned to the optically non-linear medium along a signal light path in a continuously repeating cycle, and the OPO comprises delay means for extending the time taken for signal light output from the optically non-linear medium in operation to return to the optically non-linear medium along the signal light path.

Abstract: A method of sealing a leak of fluid from a container comprises introducing a solute to a body of fluid within the container. The solute is selected so as to be soluble in the fluid at the expected conditions prevailing inside the container, and insoluble when the pressure experienced by the fluid is reduced at the site of a leak.

Abstract: The method includes the following steps—introducing a low amplitude air pressure transient into the drainage and vent system of a building in order to propagate a pressure wave from a fitting (6) into a stack (1) and the network of the drainage system;—recording the passage of the transient by use of an air pressure transducer (7) located near the fitting (6) or introduction area of the transient;—establishing a pressure versus time signature recorded by the pressure transducer (7) and sending those signals to a central data acquisition system;—the pressure transient is propagated throughout the network at an acoustic velocity and is reflected by each and every pipe termination of the network so as to establish a characteristic reflection coefficient for each pipe termination; —the characteristic reflection coefficient is compared with testing results performed initially in a perfect network with no dry trap defects or leakages and in case a different signature is of the pressure trace is recorded, the point

Abstract: An optical adapter that is arranged to connect two or more optical devices that have different connector layouts, the optical adapter comprising a material through which a plurality of waveguides is formed, the waveguides defining a first connector configuration at one end or face of the material and a second connector configuration at another, or same end or face of the material.

Abstract: A composition for use in the detection of an intoxicating drug comprising: (i) a first compound that absorbs UV radiation and generates emitted UV radiation at a wavelength absorbable by said intoxicating drug; and (ii) a second compound that absorbs UV radiation emitted by said intoxicating drug upon absorption by said intoxicating drug of said emitted UV radiation and that emits radiation in the visible spectrum is provided. In addition, methods for detecting an intoxicating drug in a sample comprising irradiating with UV radiation a sample contacted with one or two compounds that absorb UV radiation are provided.

Abstract: A diagnostic tools and methods are disclosed. The diagnostic tool is configured or operable to nominate a commonly connected component in a target system as being faulty if more than a pre-determined number of active components connected to the commonly connected component appear faulty.

Abstract: An artificial birefringent element having a repeating unit comprising at least first and second layers alternatively stacked, the first and second layers being formed of materials having different refractive indices.

Abstract: A method of sealing a leak of fluid from a container comprises introducing a solute to a body of fluid within the container. The solute is selected so as to be soluble in the fluid at the expected conditions prevailing inside the container, and insoluble when the pressure experienced by the fluid is reduced at the site of a leak.

Abstract: A diagnostics system comprising a topological map of a target system that has nodes (38, 40, 42, 44, 46, 48) that correspond to components (29, 30, 32, 34, 36) of the target system and links that correspond to connections between the components. Associated with the topological map is a knowledge store (50) that has a structure that reflects or corresponds to that of the topological map. Included in this store (50) is a plurality of sections or libraries each of which is provided for storing design specific data associated with one of the nodes (38, 40, 42, 44, 46, 48) of the topological map. Data received from one or more sensors on the target system is included in the topological map, and used together with the design specific information in the knowledge store to diagnose faults.

Abstract: This invention provides a method for fabricating geometrical diamond/matrix composites where all or a part of surfaces of the matrix are covered with a diamond film, and to fabricate hollow diamond shells using the composites where a part is uncoated with a diamond film. Hollow diamond shells were prepared by etching out of the matrix soluble with chemicals through an opening, a zone on the matrix, uncoated with diamond film. By changing the shape and the size of the geometrical matrixes, various kinds of diamond/matrix composites and diamond shells in shape and in size can be fabricated. The sizes available are between 200 nm and 2 mm.

Abstract: A measuring apparatus provides data relating to the shape of an input radiation wavefront, the wavefront shape being describable at a pre-determined location in an optical system. The apparatus includes an aberration device which provides an aberration to the input radiation wavefront, the shape of which is defined by a filter function that is complex valued and has non-mixed symmetry, and a detector having a radiation sensitive surface capable of detecting the intensity of incident radiation on the surface, the detector being coupled to an output device that provides a measure of the intensity of the incident radiation. The aberration device is configured to act on an input wavefront shape to produce first and second output radiation signals that are detected by the detector and in combination cause the output device to provide data indicating an extent to which the wavefront shape is non-planar.

Abstract: A method for transporting a fluid comprising a clathrate forming gas through a transportation system including a pipeline. The method involves subjecting the fluid to clathrate forming temperature and pressure conditions and introducing sufficient of a clathrate forming host to convert substantially all of the gas to clathrate and to form a flowable slurry. The flowable slurry is then conveyed through a pipeline to a destination. An alternative method involves transporting the fluid by means of a ring pipeline containing a carrier fluid, which includes clathrate inhibitors. Also provided is a heat pump whose working fluid is a clathrate forming composition.

Abstract: A surface relief hologram that includes two or more patterns, each pattern being sensitive to different radiation wavelengths. The hologram is made by defining relief features that are sensitive to different wavelengths, and in particular, to one wavelength that is visible to the unaided human eye and to one wavelength that is invisible to the unaided human eye. These relief features of different sensitivities are interspersed over the surface of the substrate in which the hologram is defined. By providing two patterns of different sensitivities, when the hologram is used in a security device, security is improved. Despite this improved security, the hologram can be mass manufactured using known techniques.

Abstract: A method for determining one or more parameters of a rock sample, comprising the steps of measuring the magnetic susceptibility of the sample, and determining a value of the parameter using that measured susceptibility. For example, the measured susceptibility can be used to determine fractional mineral content, permeability, cation exchange capability per unit pore volume, and flow zone indication.

Abstract: An apparatus and method for obtaining surface texture information using photometric stereo. The material for which surface height and reflectance function information is desired (“the material”) is illuminated with an illumination source emitting electromagnetic waves, preferably in the form of white light, which is consequently reflected by the material to be scanned into an imaging sensor. The position and orientation of the illumination source relative to the sensor is constant. The material is placed within or on top of a holding apparatus, such as a pane of glass, which is oriented in order to keep the illumination vector constant with respect to the imaged surface. The illumination source and sensor are moved in unison across the surface in order to progressively capture a complete image of the surface; this operation may be facilitated in practice through the use of hardware such as a flatbed scanner.

Abstract: The invention provides a novel method for absolute fringe order identification in multi-wavelength interferometry based on optimum selection of the wavelengths to be used. A theoretical model of the process is described which allows the process reliability to be quantified. The methodology produces a wavelength selection which is optimum with respect to the minimum number of wavelengths required to achieve a target dynamic measurement range. Conversely, the maximum dynamic range is produced from a given number of optimally selected wavelengths utilized in a sensor. The new concept introduced for optimum wavelength selection is scalable, i.e. from a three wavelength system to a four wavelength system, from four wavelengths to five, etc.

Abstract: A method for determining the presence of a hydrate history in a fluid involves obtaining a sample of the fluid. The sample is then cooled to determine the amount of cooling required in order to induce hydrate formation. The result is then compared to the amount of cooling required to induce hydrate formation in a sample, which has been heat treated to remove any hydrate history present, before cooling. Also provided are methods for prevention or control of hydrate formation of a fluid in a system. The degree of inhibition of hydrate formation in the fluid is monitored and then the system conditions or fluid composition are adjusted as required. Methods for carrying out monitoring of a fluid liable to form hydrates are also described.

Abstract: The invention relates to a new configuration for a laser resonator for use in combination with a solid-state laser gain medium contained within the core of a planar waveguide. The resonator has a substantially confocal negative branch unstable resonator configuration in a lateral direction, a low loss waveguide resonator configuration in a transverse direction, and the focal point of the unstable resonator is disposed outside the planar waveguide to avoid optical damage or breakdown in the gain medium. The preferred embodiment includes an effective means of transverse mode selection for the case when the planar waveguide is of the multi-mode type. The invention also provides a new low loss waveguide resonator configuration which may be used with planar waveguide gas lasers.

Abstract: The present invention provides an apparatus for use in measuring permeability of a material. The apparatus 1 comprises a non-contact probe 6 comprising an inner pipe 8 and an outer pipe 10 which are arranged coaxially; a gas inlet for admitting a flow of gas into a first space 9 defined between the inner and outer pipes; and pressure difference measuring systems DP for measuring a pressure difference &Dgr;P between said first space (P1) and a second space (P2) comprising the interior of the inner pipe 8. The probe 6 is mounted on a moveable head assembly 11 and the apparatus 1 further includes a position control system 12, 22 for controlling the movement of the head assembly 11 so as to cause the probe 6 to scan across a surface 2 of the material to be analysed, while maintaining the probe 6 at a constant distance Z from said surface 2, and for collecting pressure difference &Dgr;P measurements, using said pressure difference measuring device DP during scanning movement of the probe 6.

Abstract: According to one aspect of the present invention there is provided a coating material comprising: a functional coating component; and a fluorescent additive component whose fluorescence is substantially unquenched by the coating component, the fluorescent additive component having a peak fluorescence emission under excitation by visible or infrared light, the wavelength of that peak fluorescence emission being greater than 500 nm and lying outside the principal fluorescence absorption and emission wavelengths of the coating component.