Hybrid meta-surface lens system for long wave infrared applications (Invited Paper)

Long wave infrared imaging system present a special challenge in optical design. There are few feasible materials with sufficient transparency in the IR range and at the same time the low signal intensity requires a large aperture optic and a wide operating spectrum. Reducing the size and weight of IR imaging systems is therefor of great interest in many applications. Meta-surfaces provide a great opportunity in this respect because they are smaller in size and weight then refractive lenses. At the same time they offer direct control over the wavefront shape making it easy to created aspheric and other hard to manufacture optical functions. Meta-surfaces are by nature a diffractive lens type and so have strong chromatic effects that complicate their application for a wide spectrum. In this contribution we therefor design a hybrid lens system for LWIR that combines meta-surfaces with refractive optics. Our designs show that by co-optimization of the meta-surface and refractive lenses a compact system can be designed that meets the system requirements and with closer reproduction of the target wavefront compared to a multi-level diffractive optical element.