Abstract: The present invention relates to a high-resolution surface plasmon microscope including a heterodyne interferometer (6) for splitting an excitation light beam into at least one reference beam and at least one measurement beam directed toward a coupling medium (7) to generate a surface plasmon, said heterodyne interferometer consists essentially of guide optical fibers (12, 13, 14, 15) optically connected at a first of their ends to an optical coupler (16) and each also optically connected at their second end to a light source (1), an optical coupling medium (7), an element (17) for reflecting the reference beam, and means (28) for detecting an interferometer beam, respectively.