Visible to Longwave-infrared imaging via an inverse-designed monolithic lens

TL;DR

This paper introduces a monolithic, inverse-designed KBr lens capable of broadband, near-achromatic focusing from visible to long-wave infrared, enabling versatile hyperspectral and multi-band imaging across a continuous spectral span.

Contribution

The development of a scalable, inverse-designed monolithic lens that achieves near-constant focal length over an ultra-broad spectral range from 0.45 to 14 μm, covering multiple infrared bands.

Findings

Achieves broadband focusing from 0.45 to 14 μm with fractional bandwidth of 1.9

Maintains nearly constant focal length across the entire spectral range

Enables compact, versatile imaging platforms for various applications

Abstract

Chromatic aberrations impose a fundamental barrier on optical design, confining most imaging systems to narrow spectral bands with fractional bandwidths typically limited to $\Delta\lambda/\lambda < 1$. Here we report a monolithic, inverse-designed potassium bromide (KBr) lens that achieves broadband, near-achromatic focusing from 0.45 to 14 $\mu$m, a continuous spectral span covering the visible, near-, mid-, and long-wave infrared. This corresponds to a fractional bandwidth of 1.9, approaching the theoretical limit of 2, while maintaining a nearly constant focal length across the entire range. The 19-mm-diameter, 22.5-mm-focal-length optic enables a single compact platform for hyperspectral imaging, mid-IR microscopy, super-resolution, imaging through scattering media, and simultaneous multi-band and long-range imaging. Coupling the KBr lens with a conventional refractive element further yields a hybrid telescope that extends these capabilities. By uniting inverse design with scalable manufacturing, this approach provides a route toward broadly deployable ultra-broadband imagers for biomedicine, climate and environmental monitoring, and space-based sensing.