We report on the identification and quantitative characterization of elementary edge and screw dislocations in a colloidal smectic phase of tip-labeled rods. Thanks to the micrometer layer spacing, direct visualization of dislocations has been performed at the smectic periodicity scale by optical fluorescence microscopy. As a result, the displacement field around an edge dislocation has been experimentally established and compared with the profile predicted by elastic theory. Elementary screw

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... slocations have been also evidenced, for which the core size as well as the in situ handedness have been determined. Self-diffusion experiments performed at the individual particle level reveal for the first time nematic-like or "melted" ordering of the defect core.