Patent ID: 7370525

Claim:
A dual channel method of detecting, inflight, accretion of ice on the surface of an aircraft, the method comprising: (a) Illuminating an ice collecting surface fixed in a housing mounted on an aircraft with a light source of single linear polarization; (b) Acquiring backscattered light from said ice collecting surface using a pair of polarization sensitive light conductors when the polarization sensitivity of the first receiving light conductor is aligned to the polarization of the light source and the polarization sensitivity of the second receiving light conductor is aligned orthogonal to the polarization of the light source; (c) Coupling each receiving light conductor to a light detector to determine the backscattered light intensity for each polarization state; (d) Processing the detected light intensities in each light detector to determine ratio between the light intensity for each polarization state; (e) Processing the change in said ratio to indicate ice accretion on the ice collecting surface; (f) Activating a heat source adjacent to said housing upon indication of ice accretion; (g) Continued operating of heat source until a change in detected light intensities indicates the removal of ice on the ice collecting surface; (h) Monitoring the detected light intensities in each light detector and processing the change in detected light intensities until re-accretion of ice is detected on the ice collecting surface; (i) Processing time for re-accretion of ice to indicate the ice accretion severity.