An imaging unit including: a guide tube having an inner lateral surface extending in a longitudinal direction of the guide tube, the inner lateral surface defining an inner chamber； a lens tube having an outer lateral surface extending in a longitudinal direction of the lens tube, the lens tube being at least sectionally accommodated within the inner chamber of the guide tube； and at least one optical element which is accommodated in the lens tube； wherein the lens tube comprises a plurality of bars disposed on the outer lateral surface, each of the plurality of bars interacting with a corresponding one of a plurality of grooves recessed in the inner lateral surface of the guide tube.
