Abstract: This scanning near-field optical microscope is of the type where a light beam (19) with a diameter of at maximum .lambda./20 is emitted, or received, by a sharply pointed probe tip (13) which is scanned across the surface of a sample (11) to be investigated. The light reflected by, and/or transmitted through, the sample (11) is detected by a detector (16) and/or further processed by a computer (24). The distance between the light-emitting probe tip (13) and the sample (11) under investigation is on the order of .lambda./20 as well, so that the surface of the sample (11) is within the near-field of said probe tip (13). This optical microscope is characterized in that the gap between the probe tip (13) and the sample (11) is filled with a liquid (40) of high opacity, including any liquids with a large negative dielectric constant .epsilon., so as to attenuate the intensity of the lightwaves emitted or received by the probe tip (13) to such an extent that the penetration depth z.sub.