Abstract: Apparatus for determining the thickness of a configuration having flat, parallel surfaces that are transparent, or nearly so, to pre-specified types of energy. Embodiments comprise a mechanism for illuminating a front surface with an energy source and mechanisms for measuring reflections of the illumination from a parallel back surface. The energy is contained in a spectrum of wavelengths, the energy being refracted in components at unique wavelengths, e.g., different colored light bands, and similarly reflected from the back surface. The measuring mechanisms, e.g., spectrometers, determine the relative lateral displacement between two spectral lines in the refracted and reflected beams to enable determination of thickness. Other characteristics of the material of the configuration may be ascertained, e.g., chemical composition is ascertained by measuring the intensity of responses at multiple wavelengths and comparing this to responses of known materials.

Abstract: A system is provided for detecting accumulation of material concurrently on multiple areas of a surface in real time. In one embodiment, it is used for detecting icing of airframes while in use or on the ground while awaiting use. It may use either Time Domain Reflectometry (TDR) or Frequency Modulated Continuous Wave (FM-CW) sources to provide a known energizing signal to a transmission line sensor. The system ascertains the signal's round trip travel time in the transmission line. As material accumulates around the transmission line sensor, the medium through which the signal propagates is indicated by the change in time for the signal to propagate in relation to propagation in a reference medium, e.g., air. By employing pre-specified spectral analysis algorithms and referencing to the dielectric constant of media of interest, a determination of the occurrence, location, and the rate and type of material accumulation can be made.

Abstract: A system is provided for detecting accumulation of material concurrently on multiple areas of a surface in real time. In one embodiment, it is used for detecting icing of airframes while in use or on the ground while awaiting use. It may use either Time Domain Reflectometry (TDR) or Frequency Modulated Continuous Wave (FM-CW) sources to provide a known energizing signal to a transmission line sensor. The system ascertains the signal's round trip travel time in the transmission line. As material accumulates around the transmission line sensor, the medium through which the signal propagates is indicated by the change in time for the signal to propagate in relation to propagation in a reference medium, e.g., air. By employing pre-specified spectral analysis algorithms and referencing to the dielectric constant of media of interest, a determination of the occurrence, location, and the rate and type of material accumulation can be made.