Abstract: Wide-angled incoherent millimeter or sub-millimeter electromagnetic waves from an extended active source are used to probe substrates and their protective coatings or outer layers, such as paint or thermal insulation. The incoherent waves provide dispersion and angular variation 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, emissivity and/or transmissivity from the substrate or protective coating various according to its homogeneousness. A detector/camera is arranged to identify and resolve differences in detected power within an observed frequency range of the area under test, with this contrast in power being relative to either adjacent areas or anticipated reference levels.

Abstract: Wide-angled incoherent millimetre or sub-millimetre electromagnetic waves from an extended active source are used to probe substrates and their protective coatings or outer layers, such as paint or thermal insulation. The incoherent waves provide dispersion and angular variation 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, emissivity and/or transmissivity from the substrate or protective coating various according to its homogeneousness. A detector/camera is arranged to identify and resolve differences in detected power within an observed frequency range of the area under test, with this contrast in power being relative to either adjacent areas or anticipated reference levels.

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.