3D lithography enable ultrathin flat compound eye for moving object imaging

Abstract

With a hemispherical surface, the compound eye cameras inspired by arthropod eyes provide a large field of view (FOV), low aberration, and a large depth of field. However, to match the hemisphere-imaging plane, the cameras require a hemisphere-photoelectric sensor instead of a standard planar complementary metal oxide semiconductor (CMOS) sensor. Additionally, the hemispheric shape of the imaging system restricts the miniaturization of high-performance compound eye cameras at the millimeter scale. Here, inspired by the working principle of the Fresnel lens, an ultrathin flat compound eye (UFCE) composed of an off-axis microlens array (OMLA) was developed. 3D lithography enabled the fabrication of the UFCE with a complex morphology. Compared to the traditional artificial compound eye (ACE), the thickness of the UFCE was greatly reduced. Meanwhile, a flat substrate and ultrathin structure allowed for direct integration of the UFCE into the surface of a CMOS. The resultant UFCE had a FOV of up to 110° and a resolution close to the diffraction limit and low dispersion. Furthermore, the UFCE allowed for fast imaging of mobile objects in any plane within the depth of field, which is the unique function of the UFCE. In brief, the fabricated UFCE based on OMLA reduces the complexity of constructing compound eye cameras while significantly optimizing the volume, suggesting an alternative method for creating high-performing optical elements with the possibility of simple integration and miniaturization.