A new approach to a “model-independent” optical potential is proposed, which features the adaptive improvement of expansion base and practical estimation of the errors of the derived potential. The energy dependence of differential cross sections and analyzing powers were measured for proton elastic scattering from 28Si and 40Ca near the (p,n) reaction threshold energy. The method is applied to analyze these data. Absorption of incident flux is discussed and the absorption radius is defined. A resonance-like energy dependence of the absorption radius is found near the (p,n) reaction threshold.