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Laser-based direct writing has been around for a few years especially in the semiconductor industry know as maskless lithography (MPL). Typically the two-dimensional CAD design is transferred onto the substrate that is pre-coated with a photosensitive resin via reduction laser projection. The projected pattern was reduced given the tool's numerical aperture and scan across the surface of the substrate using either a raster or vector format. These techniques are the same ones utilized in 3D direct-write. The only difference is that know you are working with a thickness degree of freedom that can be scanned across the Z-axis. The NanoScribe GT2 has a Piezo Nanopositioning stage and a high-speed galvo scanner. In the case of two-photon lithography, the light source is a pulsed femtosecond fiber laser with the center wavelength being around 780 nm.
Diagram of a simplified optical path of a
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Two-Photon Lithography System.
Two-photon Light Source
Hight Performance NIR femtosecond laser
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