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Multi-aperture optics for wafer-level cameras

: Brückner, A.; Leitel, R.; Oberdörster, A.; Dannberg, P.; Wippermann, F.; Bräuer, A.


Journal of micro/nanolithography, MEMS and MOEMS 10 (2011), Nr.4, Art. 043010, 11 S.
ISSN: 1537-1646
ISSN: 1932-5150
ISSN: 1932-5134
Fraunhofer IOF ()
imaging system; microoptic; optical design; image processing; compound eye; camera; multiaperture; vision

Wafer-level optics is considered to yield imaging lenses for cameras of the smallest possible form factor. The high accuracy of the applied microsystem technologies and the parallel fabrication of thousands of modules on the wafer level make it a hot topic for high-volume applications with respect to quality and costs. However, the adaption of existing materials and technologies from microoptics for the manufacturing of millimeter scale lens diameters led to yield problems due to material shrinkage and z-height accuracy. A multi-aperture approach to real-time vision systems is proposed that overcomes these issues because it relies on microlens arrays. The demonstrated prototype achieves VGA (Video Graphics Array, 640×480 pixels) resolution with a thickness of 1.4 mm, which is a thickness reduction of 50% compared to single-aperture equivalents. The partial images that are separately recorded in different channels are stitched together to form a final image of the whole field of view by means of image processing. Distortion is corrected within the processing chain. The microlens arrays are realized by state-of-the-art micro-optical fabrication techniques on wafer level that are suitable for a potential application in high volume, e.g., for consumer electronic products.