A miniaturized optical head provided to equip the distal end of a beam of flexible optical fibers scanned by a laser beam, is designed to come in contact with a sample and to excite the sample confocally. This optical head includes elements for correcting spherical aberrations and focusing members. The focusing members include: at least a first lens (L4) of high convergence associated with a spherical or hemispherical lens (L5) arranged at the distal end of the optical head, and elements for correcting the axial and lateral chromatic aberration provided with a single divergent lens (3b) whose curvature is substantially centered on the pupil of the optical fiber beam and arranged at the exact distance for this pupil for which the conditions of lateral achromatization coincide with the conditions of axial achromatization this divergent lens being associated with a second convergent lens (L3a) in the form of a doublet (L3).
