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.