Tessellated Silicon-Structures for Monocentric Imagers

Compared with conventional planar optical image sensors, a curved focal plane array can simplify the lens design and improve the field of view. In this paper, we introduce the design and implementation of a segmented, hemispherical, CMOS-compatible silicon image plane for a 10-mm diameter spherical monocentric lens. To conform to the hemispherical focal plane of the lens, we use flexible gores that consist of arrays of spring-connected silicon hexagons. Mechanical functionality is demonstrated by assembling the 20-μm-thick silicon gores into a hemispherical test fixture. We have also fabricated and tested a photodiode array on a siliconon-insulator substrate for use with the curved imager. Optical testing shows that the fabricated photodiodes achieve good performance; the hemispherical imager enables a compact 160 ° field of view camera with 480% fill factor using a single spherical lens.

This work has been selected as Featured Article in Nature Microsystems & Nanoengineering.