Fabrication of micro-structures for optically driven micromachines using   two-photon photopolymerization of UV curing resins
  Two-photon photopolymerization of UV curing resins is an attractive method for the fabrication of microscopic transparent objects with size in the tens of micrometers range. We have been using this method to produce three-dimensional structures for optical micromanipulation, in an optical system based on a femtosecond laser. By carefully adjusting the laser power and the exposure time we were able to create micro-objects with well-defined 3D features and with resolution below the diffraction limit of light. We discuss the performance and capabilities of a microfabrication system, with some examples of its products. 
Theodor Asavei and Timo A. Nieminen and Norman R. Heckenberg and   Halina Rubinsztein-Dunlop