Abstract: An apparatus, such as an extruding machine, configured to form a sheath, e.g. insulative layer, over an elongate member, e.g. a wire cable including an extruder to apply the material forming the sheath, a drive mechanism configured to move the elongate member through the extruder at a line speed, a thickness sensor to determine the thickness of the material, and a controller. The controller is programmed to determine a deviation between the actual material thickness a desired thickness, determine a correction factor value based on the deviation between the actual thickness and the desired thickness of the material applied, and adjust the line speed, via the drive mechanism, based on the line speed, an extruder feeder speed, the correction factor value and a material factor value that is based on rheological properties of the material. A method of operating such an extruding machine is also presented.

Abstract: An apparatus, such as an extruding machine, configured to form a sheath, e.g. insulative layer, over an elongate member, e.g. a wire cable including an extruder to apply the material forming the sheath, a drive mechanism configured to move the elongate member through the extruder at a line speed, a thickness sensor to determine the thickness of the material, and a controller. The controller is programmed to determine a deviation between the actual material thickness a desired thickness, determine a correction factor value based on the deviation between the actual thickness and the desired thickness of the material applied, and adjust the line speed, via the drive mechanism, based on the line speed, an extruder feeder speed, the correction factor value and a material factor value that is based on rheological properties of the material. A method of operating such an extruding machine is also presented.

Abstract: A device for detecting seismic acceleration includes a proof mass; a base for providing a sensor acceleration, relative to the proof mass, based on the seismic acceleration; and an optical fiber portion operatively connected between the proof mass and the base for providing a fiber tension based on the sensor acceleration. A fiber Fabry-Perot interferometer (FFPI) in the optical fiber portion provides an optical characteristic representative of the fiber tension. A compensator applies a compensating tension to the FFPI to compensate for a change of the optical characteristic due to a temperature change of the FFPI.

Abstract: A system and method for stabilizing a plurality of output frequencies (wavelengths) of a plurality of lasers (106). The laser beams are combined using optical multiplexer (110) and coupled into length-imbalanced (armlength-mismatched) Mach-Zehnder interferometer (MZI) (114) having an optical modulator (e.g. AOM) (122) in one of its arms. The output of the MZI is divided into corresponding beams via optical demultiplexer (128) and each beam is detected by a respective photo-diode (PD) (134). The individual electric signals, so generated, are demodulated using a corresponding plurality of phase-responsive devices (138) and the resulting phase-signals are directed to a plurality of servo-controllers (148) to control the central frequency of the respective lasers (106) via a corresponding plurality of feedback loop circuits (150). The lasers (106) can have different central frequencies which can also be individually tunned using offset modules (141) in the phase-responsive devices (138).

Abstract: A device for detecting seismic acceleration including a proof mass; a base for providing a sensor acceleration, relative to the proof mass, based on the seismic acceleration; an optical fibre portion operatively connected between the proof mass and the base for providing a fibre tension based on the sensor acceleration, a fibre Fabry-Perot interferometer (FFPI) in the optical fibre portion for providing an optical characteristic representative of the fibre tension, and a compensator for applying a compensating tension to the FFPI to compensate for a change of the optical characteristic due to a temperature change of the FFPI.

Abstract: A system and method for stabilising a plurality of output frequencies (wavelengths) of a plurality of lasers (106). The laser beams are combined using optical multiplexer (110) and coupled into length-imbalanced (armlength-mismatched) Mach-Zehnder interferometer (MZI) (114) having an optical modulator (e.g. AOM) (122) in one of its arms. The output of the MZI is divided into corresponding beams via optical demultiplexer (128) and each beam is detected by a respective photo-diode (PD) (134). The individual electric signals, so generated, are demodulated using a corresponding plurality of phase-responsive devices (138) and the resulting phase-signals are directed to a plurality of servo-controllers (148) to control the central frequency of the respective lasers (106) via a corresponding plurality of feedback loop circuits (150). The lasers (106) can have different central frequencies which can also be individually tunned using offset modules (141) in the phase-responsive devices (138).

Abstract: An apparatus for interferometric sensing, comprising a plurality of single-longitudinal mode laser sources to each provide radiation at a corresponding plurality of selected wavelengths, and at least one modulator to frequency or phase modulate the radiation from each laser; a plurality of Fabry-Perot interferometers formed by Bragg Gratings written into optical fibre, each interferometer being responsive to one of the said plurality of wavelengths to each produce a reflected or transmitted optical output signal dependent on the corresponding interferometer path length; and one or more demodulators to demodulate the optical output signals and produce a corresponding plurality of measurement signals indicative of optical path lengths of the respective interferometers.

Abstract: An apparatus for interferometric sensing, comprising a plurality of single-longitudinal mode laser sources to each provide radiation at a corresponding plurality of selected wavelengths, and at least one modulator to frequency or phase modulate the radiation from each laser; a plurality of Fabry-Perot interferometers formed by Bragg Gratings written into optical fibre, each interferometer being responsive to one of the said plurality of wavelengths to each produce a reflected or transmitted optical output signal dependent on the corresponding interferometer path length; and one or more demodulators to demodulate the optical output signals and produce a corresponding plurality of measurement signals indicative of optical path lengths of the respective interferometers.