We report on the transport of ultracold atoms with optical tweezers in the non-adiabatic regime i.e. on a time scale on the order of the oscillation period. To quantitatively interpret our data, we provide a fruitful analogy between the transport and the Fraunhofer diffraction of an object having a transmittance with the same shape as the one of the velocity profile imposed on center of the trap. The damping of the Kohn's mode due to the non-linear mixing turns out to be reminiscent of the effect of a finite coherence source for its optical counterpart.