The 3D printing process uses a liquid resin, which is hardened at precisely the correct spots by a focused laser beam. The focal point of the laser beam is guided through the resin by movable mirrors and leaves behind a hardened line of solid polymer a few hundred nanometers wide.
Additive Manufacturing Technologies refers to manufacturing techniques which build up three-dimensional structures by sequentially adding material. Usually this is done by decomposing a part into thin layers and sequentially stacking up layer-by-layer.
Two-photon polymerisation (2PP) is a technique to fabricate three dimensional structures with resolutions down to 100nm (see St. Stephan’s cathedral and Tower Bridge). An fs-pulsed laser (usually emitting at 800nm) is focussed in the volume of a photopolymerisable formulation. Polymerisation only occurs in the focal point, where the intensity of the absorbed light is highest. This technique is the first AMT capable of fabricating true 3D structures without the necessity of layer-by-layer manufacturing.
In the video, a race car with dimensions of 330x130x100µm3 is fabricated. The structure consists of 100 layers, each made of an average of 200 polymer lines. It is finished in 4 minutes and resembles the CAD file at a precision of ±1µm.