FFT Based Angle Detection of Fiber Glass Layers

We propose an FFT based method to detect the orientation of fiber glass layers. To this end we apply the 2D FFT transform to the radar image data in surface orthogonal coordinates and apply a filtering in frequency space. Finally, we use a CFAR detector to calculate the relevant fiber directions. The method is verified by a test setup, where we use a sample with changing fiber orientation. We observe that the method is able to detect the correct fiber orientation angles up to an error of less than 0.1 degree.