Resolution of conventional laser-based advanced manufacturing (AM) techniques are limited by the wavelength of the laser and diffraction.  Diffraction limit sets the smallest features size and thus poses a major obstacle for using these laser-based methods to fabricate nanoscale features.  To overcome this challenge and fabricate in the nanoscale, two-photon lithography was developed to print microstructures beyond the diffraction limit.

LLNL has been at the forefront of this new technology, developing a TPL system, FemtoProWrite, that can deliver high-throughput 3D printing at the nanoscale.  Current TPL systems such as FemtoProWrite can be used to print polymers with very fine nanoscale features, but not for ceramics with comparable feature sizes. 

In order to produce 3D printed ceramics with extremely fine details using TPL, a dip-in approach is needed where immersion oil, required for a conventional TPL system, is no longer necessary.  In the dip-in TPL configuration, the laser passes through a high numerical aperture (NA) objective lens directly into the optically transparent resist in which the printed object is then formed. For this dip-in approach to work, however, the photoresist must meet the requirements of the high NA objective lens, e.g. a refractive index that is similar to immersion oil (1.52).  LLNL researchers have been able to produce such RI matching resins, allowing the production of ceramic components with ultra-fine submicron features.