A far-field optical microscope capable of reaching nanometer-scale resolution using the in-plane image magnification by surface plasmon polaritons is presented. The microscope utilizes a microscopy technique based on the optical properties of a metal-dielectric interface that may, in principle, provide extremely large values of the effective refractive index n.sub.eff up to 10.sup.2-10.sup.3 as seen by the surface plasmons. Thus, the theoretical diffraction limit on resolution becomes .lamda./2n.sub.eff, and falls into the nanometer-scale range. The experimental realization of the microscope has demonstrated the optical resolution better than 50 nm for 502 nm illumination wavelength.