LightFab: Selective Laser Etching, Subtractive 3D Printing with Transparent Materials

The LightFab 3D printer is for makers and inventors who are involved in more complex projects, aspiring to work with glass as well as etching. The Germany-headquartered company has created a multi-faceted machine in the LightFab, which includes all the following along with the 3D microscanner:

• High precision 3-axis system for stepping
• FS-laser
• Camera and vision system for automatic alignment
• Laser safety and an innovative CAD/CAM/nc software package

LightFab created the innovative new hardware specifically for their selective laser etching, a ‘subtractive’ 3D printing process. It can also be used for laser writing in materials that are transparent, such as:

• Waveguide writing
• 2-photon-polymerization
• Backside ablation
• Crack-free markings

“We offer you the production of glass micro-parts spanning from prototypes, small and large lot sizes or enable you to produce the parts on your own using our micro scanners,” states the LightFab team.

SLE is a two-part process, consisting of rapid laser radiation which “is focused to micrometer-sized spots into a material that is transparent to the wavelength of the laser radiation used,” as Martin Hermans, Jens Gottmann, and Jürgen Ortmann of LightFab explain, continuing:

“The laser radiation is absorbed, only at the focal spot, by the material because of nonlinear absorption processes occurring at the high intensities that are applied (>1012W/cm2). The absorbed energy leads to internal heating and subsequent quenching of the material in a very confined volume, resulting in a permanent modification of the transparent material. This laser modification does not consist of cracks and can be applied with extreme precision.”

In the second part, the piece is moved into an etching bath.

“The etching starts at the surface and works its way into the workpiece, washing out all the material that was previously modified with the laser radiation,” the team explains.

Users interested in such technology should benefit from SLE as little stress is placed on the material, and support structures are not necessary.

Reindeer with movable legs [Image: LightFab]

“Although SLE surfaces feature an initial roughness on the order of Ra ~200nm, the surfaces do not have microcracks or sub-surface defects that cause failure in cases of mechanical load. This makes applications in the field of flexure bearings possible,” states the LightFab team.

“The current state of the technology in fused silica is that first-time-right machining is possible for complex 3D parts <7mm in height with a precision of about 10μm and a maximum tunnel length of 10mm. Larger precision or longer tunnel lengths are feasible, but often make iterations of production and measurements necessary before the part fits the precision requirements.”

Glass parts are useful for the medical industry, precision mechanics, and optics. With SLE laser technology, 3D devices can be made from materials most users have not considered, such as silica, ultralow expansion glass, and sapphire. The technology also allows for parts to be made with more complex interiors like cavities and tunnels, as well as other moving parts.

Microfluidical chip for capillary electrophoresis

LightFab has collaborated with other companies to create items such as the following:

• Cell-sorter for antibiotic resistance tests
• Microfluidical cross-section chip in fused silica
• Lava nozzle inset for laser particle accelerators
• Microfluidical chip for capillary electrophoresis

You can find out more about LightFab here, as well as downloading the data sheet for the LightFab 3D printer and exploring their other products. Discuss in the LightFab forum at 3DPB.com.