Near-field optical microscope

A near-field optical microscope comprising an optics module (2) and a positioning module (4). The optics module houses a near-field probe formed at the end of a single-mode fibre (38); an ellipsoid mirror (41) having a hole arranged axially in its base to allow placement of a sample (P) from below at its lower focus; a section of multi-mode optical fibre (7) positioned with its aperture at the upper focal point of the ellipsoid mirror (41) to collect the optical signal and pass it on to a detector; and a lens (36) arranged to allow independent imaging of the sample region and having a hole extending through its optical axis through which passes a sheath (9) in which the multi-mode optical fibre (7) is slidably arranged so that the positions of the fibre aperture and the lens can be independently adjusted along the optical axis. The positioning module (4) houses coarse and fine positioning units (42 and 43) and a sample holder (45). The modules (2 and 4) are releasably coupled to each other so that the positioning module (4) can be detached without disturbing the alignment of the optical components of the optics module (2).