Only small irregularities are visible in this case because smooth topography is tracked by feedback. The Fig.4 presents the spherulite organization of polypropylene. It is seen that lamellae structure of spherulites is more visible on Fig.4b. The contrast of the amplitude-image will increase after either the scanning velocity increasing or feedback gain decreasing. The optimal scanning parameters for amplitude-image should be particularly selected for every sample.
Strong contrast is the typical feature of the imaging of the oscillating cantilever phase shift.
The phase image is acquired by simultaneous measuring of topography and cantilever phase shift during scanning in semicontact mode. This strong contrast can be explained by the dependence of the phase shift on the surface properties. The phase shift depends not only on topography but also on adhesion, elasticity, and damping. Because of it phase image enable to use it for revealing the surface areas with different properties. For example it is possible to reveal the distribution of the components in composite material, the distribution of the amorphous and crystalline phases.