Average slope subtraction

Figure 1.6: Avreage slope subtraction.

Surface images obtained usually has some slope, which can appear due to different causes. It can be real surface slope; can be temerature drift, that causes sample to move during scanning; it can be due to piezoceramic manipulator non-linearity. However, these reasons lead to general surface slope, and it prvent object structure to be exposed. To avoid it average slope plane is subtracted from the initial matrix. Let's explain it on one-dimensional example (see pic. 1.6).

Matrix with narrow data range is obtained as a result, and small details are represented with greater number of colours and become more visible. Piezomanipulator non-linearity can cause the surface image to be concave. In this case more complex surface - parabolic or hyperbolic - needed to be subtracted from the surface image.