A method for SANS data analysis is proposed which enables one to directly compute the average mean, Gaussian and square mean curvatures of the interface in systems with a micro-phase-separated bicontinuous structure. This method also leads to a Sd reconstruction of the connected internal interface which allows one to visualize the mesoscopic scale morphology of the material, The method has been successfully applied to various bicontinuous structures such as: microemulsions made of surfactant, water and oil, porous silica glasses and phase-separated homopolymer blends. In this lecture, we show examples of analyses of SANS data taken from one-phase bicontinuous microemulsions at the hydrophile-lipophile-balance temperature and a light scattering intensity taken from a symmetric micro-phase-separated polymer blend at the late stage of spinodal decomposition.