Profile measurement by the combined method (optimal and automatic selection of the standard area)

The combined method, which combines the generalized 2-point method with the inclination method, has been developed to measure profiles that include high-frequency components whose spatial wavelengths are shorter than the distance between the two probes. In this combined method, some data points in the profile evaluated by the generalized 2-point method are chosen as the standard area and used to determine the relative heights among the data groups of the inclination method. In the present paper, we propose an automatic selection method that can be select the reference points optimally and quickly. By using this proposed selection method, the profile evaluated by the combined method can reach the highest accuracy that is determined by the characteristics of the probes, such as the resolution and the stability. Computer simulations and experimental results confirming the effectiveness of the proposed selection method are also presented in this paper.