Optical Remote Detection of Ice on Aircraft Surfaces

An imaging spectroscopic technique is undergoing development for use in remote detection of ice and mapping of the thickness of ice on aircraft surfaces. The technique is based on the variation of local spectral reflectance with the depth of ice and/or water on a surface of known aircraft material (typically, aluminum). The spectrum of white light reflected from each surface point includes absorption dips characteristic of any water or and/or ice present at that point, as distinguished from the relatively flat spectral reflectance of aluminum. Thus, the local thickness of ice (and, optionally, water) can be computed from the local spectral reflectance, and the thickness of ice can be mapped by performing this computation for all points in the image.