Fabrication of microlenses in polymer layers with excimer laser ablation

Main Researcher: Kris Naessens

Excimer laser ablation is employed as a direct-write process for microlens fabrication in polymer materials. The technique is based on 'scanning contour ablation' which means that the polymer substrate is making successive circular moves ('contours') while the laser is continuously firing pulses ('scanning'). An algorithm was developed for optimizing those contour scan velocities and contour diameters in order to fabricate an arbitrary microstructure in the substrate. Optical surfac finish is obtained by ablating the lens deeper into the surface.

Spherical lenses have been succesfully fabricated with this technique and wavefront measurements (with a Mach-Zehnder interferometer) indicated that aberrations down to ë/10 are obtained.

This microfabrication technique has some obvious benefits:
- direct-write and contactless fabrication
- only a very basic micromachining set-up is required with two circular apertures instead of complex or halftone masks, which are common in other fabrication techniques
- insertion of microstructures on top surfaces of opto-electronic modules, even in a late phase of the heterogeneous assembly process, is possible
- the process is very flexible in terms of microlens shape, diameter, focal length, ...

microstructures with optical surface finish, fabricated with scanning contour ablation

Other people involved:

• Kris Naessens

PhD thesises