Transverse additive manufacturing and optical evaluation of miniature thin lenses in ultracompact micro multi-spherical compound eye

An ultracompact micro multi-spherical compound eye (MSCE) was designed to solve the defocus problem existing in traditional curved compound eye for planar photoelectric detection. The MSCE was integrated with a series of thin lenses located on multiple spherical surfaces with various radii. The overall diameter of the designed MSCE was 86.3 μm, and it was composed of 37 ommatidia with a diameter of 7.5 μm. The transverse additive manufacturing method via two-photon polymerization (TPP) was used to achieve precise fabrication of MSCE. Comparison experiments were performed to show the superiority of this method in quality and efficiency in thin lenses manufacturing compared with traditional curved compound eye methods. Furthermore, the spot diagrams and Modulation Transfer Function (MTF) curves were used to evaluate the optical imaging. The imaging of letters 'C', 'U' and 'T' through the fabricated MSCE were successfully detected by the established imaging system, respectively. The imaging quality was evaluated using the root-mean-square value in the Hexcone model. The maximum optical intensity of MSCE increased by 63.9% compared with that of a single-spherical compound eye (SSCE). Finally, the actual field of view (FOV) angle of MSCE was detected as ∼80°, which was almost consistent with the theoretical angle of 77.6°. It is expected that this work will promote micro-optics components to be applied in the miniaturization and integration of optics systems for imaging, sensing and illuminating.