Large field-of-view thermal imaging via all-silicon meta-optics

Abstract

A broad range of imaging and sensing technologies in the infrared require large field-of-view (FoV) operation. To achieve this, traditional refractive systems often employ multiple elements to compensate for aberrations, which leads to excess size, weight, and cost. For many applications, including night vision eye-wear, air-borne surveillance, and autonomous navigation for unmanned aerial vehicles, size and weight are highly constrained. Sub-wavelength diffractive optics, also known as meta-optics, can dramatically reduce the size, weight, and cost of these imaging systems, as meta-optics are significantly thinner and lighter than traditional refractive lenses. Here, we demonstrate 80° FoV thermal imaging in the long-wavelength infrared regime (8–12 µm) using an all-silicon meta-optic with an entrance aperture and lens focal length of 1 cm.

Wide-Field-of-View, Large-Area Long-Wave Infrared Silicon Metalenses

“…To mitigate the issue, Ge coupled with a ZnS antireflection layer has been adopted for metalens fabrication to suppress parasitic absorption across the LWIR band . The challenge of coma aberration suppression and expanding the FOV has nonetheless not been tackled by these pioneering investigations, except in a recent report . More recently, metalens arrays comprising five lens, each covering a subsection of the FOV, have been implemented to demonstrate LWIR imaging spanning a horizontal FOV exceeding 60° upon image stitching in postprocessing .…”

“…26 The challenge of coma aberration suppression and expanding the FOV has nonetheless not been tackled by these pioneering investigations, except in a recent report. 27 More recently, metalens arrays comprising five lens, each covering a subsection of the FOV, have been implemented to demonstrate LWIR imaging spanning a horizontal FOV exceeding 60°upon image stitching in postprocessing. 28 The approach is however hardly scalable to WFOV applications as a large FOV (e.g., 100°) in both horizontal and vertical directions would require tens of individual metalenses, severely curtailing the optical throughput while escalating system complexity.…”

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“…Moreover, highly integrated devices like metalens endoscopes [24] , phase gradient microscopy [25] , polarization cameras [26] , and pancake meta-optics cameras [27] showcase the broad application prospects of metalens technology. In recent years, LWIR metalenses have shown significant progress, particularly in wide field-ofview imaging [28][29][30][31][32] and broadband achromatic imaging [33][34][35][36][37][38][39][40] . However, to date, the development of LWIR broadband achromatic metalenses with dynamically tunable focus, which are suitable for both coaxial and off-axis applications, remains an important area of research.…”