Abstract: Incoherent millimeter wave, sub-millimeter wave and terahertz test signals are used to probe metal substrates covered by a protective coating or outer layer, such as paint or thermal insulation, obscuring direct assessment of the substrate. The incoherent test signals, provide signal dispersion and angular variation of the test signals with respect to angular incidence to the substrate. Illumination of the substrate permits differentiation between un-corroded and corroded sections of the sample because reflectivity (and emissivity) from a metal-based substrate is heavily dependent on the surface resistivity which is dependent on the corroded state. A detector/camera is arranged to pick up reflections from the substrate and an associated control system identifies regions of the sample that reflect the test signal illumination differently or otherwise indicate a variation from a reference value.

Abstract: Incoherent millimeter wave, sub-millimeter wave and terahertz test signals are used to probe metal substrates that are covered by a protective coating or outer layer, such as paint or thermal insulation, obscuring direct assessment of the substrate. The incoherent test signals, which may be from a naturally occurring passive source (such as the sky) and/or from an active noise source, provide signal dispersion and angular variation of the test signals with respect to angular incidence to the substrate. Illumination of the substrate permits differentiation between un-corroded and corroded sections of the sample because reflectivity (and emissivity) from a metal-based substrate is heavily dependent on the surface resistivity which in turn is dependent on the corroded state.

Abstract: Incoherent millimetre wave, sub-millimetre wave and terahertz test signals are used to probe metal substrates covered by a protective coating or outer layer, such as paint or thermal insulation, obscuring direct assessment of the substrate. The incoherent test signals, provide signal dispersion and angular variation of the test signals with respect to angular incidence to the substrate. Illumination of the substrate permits differentiation between un-corroded and corroded sections of the sample because reflectivity (and emissivity) from a metal-based substrate is heavily dependent on the surface resistivity which is dependent on the corroded state. A detector/camera is arranged to pick up reflections from the substrate and an associated control system identifies regions of the sample that reflect the test signal illumination differently or otherwise indicate a variation from a reference value.

Abstract: Incoherent millimetre wave, sub-millimetre wave and terahertz test signals are used to probe metal substrates that are covered by a protective coating or outer layer, such as paint or thermal insulation, obscuring direct assessment of the substrate. The incoherent test signals, which may be from a naturally occurring passive source (such as the sky) and/or from an active noise source, provide signal dispersion and angular variation of the test signals with respect to angular incidence to the substrate. Illumination of the substrate permits differentiation between un-corroded and corroded sections of the sample because reflectivity (and emissivity) from a metal-based substrate is heavily dependent on the surface resistivity which in turn is dependent on the corroded state.

Abstract: An array of feedhorns feeds detected radiation through waveguides to diode-based mixers to produce modulated intermediate frequency (“IF”) signals. The mixers and waveguides are accommodated on a substrate surface and multiple substrates can be layered up to support a two-dimensional array of waveguide openings in a face of a waveguide/mixer block. A feedhorn block is brought into register with this face so that each waveguide opening connects with a feedhorn. An end portion of each feedhorn is drilled into the opening of a respective waveguide. The main feedhorn block and the waveguide/mixer block are then assembled into registration. This method of construction avoids transverse interfaces in the walls of the feedhorns or waveguides just at the point where the transition is made from one to another.

Abstract: In a terahertz imaging system, a scanning component for scanning a field of view is tracked by an optical beam to obtain positional information. The optical tracking beam can be steered by the scanning component for example by reflection, refraction or diffraction. The steered tracking beam can then be detected by a spatially sensitive detector such as a charge-coupled device array. In a preferred embodiment, the output of a terahertz detector receiving terahertz radiation from the scanned field of view is used to modulate the tracking beam. This means that the spatially sensitive detector can provide an image directly derived from the scanning of the field of view by the terahertz radiation.

Abstract: In a terahertz imaging system, a scanning component for scanning a field of view is tracked by an optical beam to obtain positional information. The optical tracking beam can be steered by the scanning component for example by reflection, refraction or diffraction. The steered tracking beam can then be detected by a spatially sensitive detector such as a charge-coupled device array. In a preferred embodiment, the output of a terahertz detector receiving terahertz radiation from the scanned field of view is used to modulate the tracking beam. This means that the spatially sensitive detector can provide an image directly derived from the scanning of the field of view by the terahertz radiation.

Abstract: In a terahertz radiation detection system, such as a terahertz camera, an array of feedhorns feeds detected radiation through waveguides to diode-based mixers for mixing with a local oscillator to produce modulated intermediate frequency (“IF”) signals that can be amplified and used in imaging. The mixers and waveguides are accommodated on the surface of a substrate and multiple substrates can be layered up to support a two-dimensional array of waveguide openings in a face of a waveguide/mixer block. A feedhorn block is brought into register with this face so that each waveguide opening connects with a feedhorn. In order to improve both manufacturing speed and performance, an end portion of each feedhorn is drilled into the opening of a respective waveguide. The main feedhorn block and the waveguide/mixer block are then assembled to bring the main body of each feedhorn into registration with an end portion.

Abstract: This invention relates to heating apparatus and methods with particular applications for growing a nanofibre, and to nanotips fabricated by such methods and apparatus. Embodiments of the invention can be implemented to provide nanotips for electron gun sources and scanning probe microscopy. A nanotip fabrication apparatus includes a heater for heating an object in the presence of an electric field. The heater comprises: a substantially planar electrically conductive heating element configured to define at least one aperture; a support to mount the heated object such that it protrudes through said aperture; and at least one electrical connection to said heating element. In use, the heating element can be biased by said at least one electrical connection such that the electric field in the vicinity of the object is substantially perpendicular to the plane of the element.

Abstract: In a terahertz radiation detection system, an array of harmonic transmitters/receivers can be scanned across a field of view. By using an unbalanced pair of Schottky diodes in the mixer of a heterodyne receiver, the receiver can be converted to a transmitter, generating terahertz radiation at even harmonics of the local oscillator. By using local oscillators of different frequencies in the transmitter and a receiver, the receiver can detect the generated radiation. In alternative arrangements, the local oscillator of the transmitter might have the same frequency as that of the receiver but be modulated, either directly or simply as a result of the transmitter being scanned across the field of view. If modulated directly, it might be amplitude or frequency modulation, these having different advantages. A receiver can be switched between acting as a transmitter and as a receiver by turning on and off an electrical bias to the Schottky diode pair.

Abstract: A semiconductor wafer manufactured with a precise crystallographic-orientation alignment mark and a method of manufacturing. The method of manufacturing may include forcibly directing a carrier medium containing an abrasive material through a stencil to effect abrasive impact removal of a semiconductor surface in a defined machining area. The abrasive impact removal may be part of an automated machining process.