Distortion-free multi-element Hypergon wide-angle micro-objective obtained by femtosecond 3D printing.

In this Letter, we present a 3D-printed complex wide-angle multi-element Hypergon micro-objective, composed of aspherical lenses smaller than 1 mm, which exhibits distortion-free imaging performance. The objective is fabricated by a multi-step femtosecond two-photon lithography process. To realize the design, we apply a novel (to the best of our knowledge) approach using shadow evaporation to create highly non-transparent aperture stops, which are crucial components in many optical systems. We achieve a field-of-view (FOV) of 70°, at a resolution of 12.4 µm, and distortion-free imaging over the entire FOV. In the future, such objectives can be directly printed onto complementary metal-oxide-semiconductor (CMOS) imaging chips to produce extremely compact, high-quality image sensors to yield integrated sensor devices used in industry.