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Laser lithographic approach to micro-optical freeform elements with extremely large sag heights
Jens Dunkel1, Frank Wippermann, Andreas Brückner
1Fraunhofer Institute for Applied Optics and Precision Engineering, A.-Einstein-Str. 7, 07745 Jena, Germany. Jens.Dunkel@iof.fraunhofer.de
Optics Express
|March 16, 2012
Summary
Researchers developed a new laser lithography method to fabricate complex micro-optical refractive freeform arrays (RFFAs) for miniaturized artificial compound eye cameras. This advanced fabrication technique enables high-accuracy production of freeform optics essential for next-generation imaging systems.
Area of Science:
- Optics and Photonics
- Microfabrication Technologies
- Imaging Systems
Background:
- Artificial compound eye cameras offer significant miniaturization potential for imaging systems.
- Micro-optical refractive freeform arrays (RFFAs) can enhance imaging performance but face fabrication challenges due to complex, high-accuracy surface profiles.
- Existing fabrication technologies are insufficient for producing RFFAs with large sag heights and extreme accuracies.
Purpose of the Study:
- To develop and demonstrate an improved fabrication process for micro-optical refractive freeform arrays (RFFAs) using laser lithography.
- To achieve high-accuracy fabrication of arbitrary freeform structures suitable for artificial compound eye optics.
- To enable cost-efficient mass production of advanced imaging systems.
Main Methods:
- A novel laser lithographic process involving multiple coating and exposure steps was developed.
- An empirical process model-based compensation strategy was implemented to minimize surface deviations.
- Spherical micro lens arrays were fabricated to demonstrate and validate the process accuracy.
Main Results:
- The developed laser lithography process successfully fabricated arbitrary freeform structures with sag heights up to 60 µm.
- Fabricated micro-optical elements exhibited shape deviations below 1.3 µm (rms), demonstrating high accuracy.
- The process is suitable for creating master structures for cost-efficient mass replication.
Conclusions:
- Laser lithography, combined with a compensation strategy, provides a viable method for fabricating complex RFFAs.
- The demonstrated accuracy meets the stringent requirements for artificial compound eye optics.
- This advancement paves the way for mass production of miniaturized, high-performance imaging systems.
