Method and device for determining the thickness and growth rate of an ice layer

A method and a device are disclosed for determining the thickness and growth rate of an ice layer on structural component parts, particularly of aircraft, wherein the thickness and growth rate of an ice layer are determined and displayed in a simple, economical and dependable manner. To this end, a method is disclosed by which the radiation incident on a surface covered by an ice layer or disturbing layer is separated spectrally by a holographic grating connected with a line receiver into enough wavelength regions that a correction of the ice absorption is achieved by comparing the measured radiation with a stored reflection curve of an uncoated surface and by combining the comparison values and determining the peak area in the wavelength region of the ice absorption, and wherein from the thickness of the ice layer and disturbing layer and the ice thickness values obtained in the measurement intervals the growth rate of the ice layer is determined and displayed. The device for carrying out the method comprises a window which is provided in the surface covered by an ice layer or disturbing layer and through which a beam impinges on a holographic grating via an optical imaging system and an entrance slit, is separated by wavelength, imaged on a line receiver and evaluated by a controlling and evaluating unit, and the evaluated data are displayed on a display.