Inverse Vulcanized Glass: Manufacturable Sulfur‐Rich Plastic Optics for Long‐Wave Infrared Imaging

ABSTRACT Polymer‐based optical materials have transformed visible and near‐infrared photonics through their low cost and scalability; however, most remain opaque in the long‐wave infrared (LWIR) due to vibrational absorption. Here, we report inverse vulcanized glass (IVG) as a sulfur‐rich plastic optical glass capable of supporting LWIR imaging. Control of sulfur melt homogeneity during inverse vulcanization yields highly transparent polymer glasses with elevated sulfur content (∼80‐wt.%) and high refractive index ( n ≈ 1.9), enabling fabrication of high‐performance freestanding Fresnel lenses by melt processing. Systematic microbolometer imaging across composition, optical path length, and temperature establishes a multivariate framework for LWIR performance, where higher sulfur content and reduced thickness minimize optical attenuation. Under ambient conditions, LWIR imaging is achieved without parasitic thermal gradients, with contrast governed by emissivity differences between objects. These results show that LWIR image formation in polymer optics is dictated by coupled radiative emission and material transmission, establishing design rules for polymer‐based infrared optical systems.