An interferometer and a method for generating scattered light interference are provided. A beam splitter is provided by a single metal nanoparticle to split an incoming excitation light. Scattered light from the single metal nanoparticle and its mirror image shows interference in both spatial and spectral domains. A mirror modifies the spatial distribution of elastic light scattering of the single metal nanoparticle. A large spectral width of the scattered light enables a distance measurement without scanning the mirror.