Miniaturized optical head with high spatial resolution and high sensitivity, especially for fibred confocal fluorescence imaging

A miniaturized optical head provided to equip the distal end of a bundle of flexible optical fibres scanned by a laser beam, said optical head being configured to come into contact with a sample and to excite said sample in a confocal manner the optical head comprising:

• means for correcting spherical aberrations;
• and
• focusing means,
• wherein the focusing means comprises
• at least a first strongly convergent lens combined with a spherical or hemispherical lens arranged at the distal end of the optical head, and
• means for correcting axial and lateral chromatism that are provided with a single divergent lens the curvature of which is substantially centered on the pupil of the bundle of optical fibres and arranged at the correct distance from this pupil for which the lateral achromatization conditions coincide with the axial achromatization conditions, the divergent lens being combined with a second convergent lens in the form of a doublet,
• wherein the means for correcting spherical aberrations comprise a third convergent lens, the thicknesses of the first and third convergent lenses being determined so as to correct the cumulative spherical aberration on the convergent diopters.

A miniaturized optical head provided to equip the distal end of a bundle of flexible optical fibres scanned by a laser beam, said optical head being configured to come into contact with a sample and to excite said sample in a confocal manner the optical head comprising:

• means for correcting spherical aberrations;
• and
• focusing means,
• wherein the focusing means comprises
• at least a first strongly convergent lens combined with a spherical or hemispherical lens arranged at the distal end of the optical head, and
• means for correcting axial and lateral chromatism that are provided with a single divergent lens the curvature of which is substantially centered on the pupil of the bundle of optical fibres and arranged at the correct distance from this pupil for which the lateral achromatization conditions coincide with the axial achromatization conditions, the divergent lens being combined with a second convergent lens in the form of a doublet,
• wherein said doublet is constructed of glass and comprises a pair of glasses having an index difference and a chromatic dispersion difference so as to compensate for the chromatic aberrations of the convergent lenses.