Multispectral camouflage for infrared, visible, lasers and microwave with radiative cooling

Abstract

Interminable surveillance and reconnaissance through various sophisticated multispectral detectors present threats to military equipment and manpower. However, a combination of detectors operating in different wavelength bands (from hundreds of nanometers to centimeters) and based on different principles raises challenges to the conventional single-band camouflage devices. In this paper, multispectral camouflage is demonstrated for the visible, mid-infrared (MIR, 3–5 and 8–14 μm), lasers (1.55 and 10.6 μm) and microwave (8–12 GHz) bands with simultaneous efficient radiative cooling in the non-atmospheric window (5–8 μm). The device for multispectral camouflage consists of a ZnS/Ge multilayer for wavelength selective emission and a Cu-ITO-Cu metasurface for microwave absorption. In comparison with conventional broadband low emittance material (Cr), the IR camouflage performance of this device manifests 8.4/5.9 °C reduction of inner/surface temperature, and 53.4/13.0% IR signal decrease in mid/long wavelength IR bands, at 2500 W ∙ m−2 input power density. Furthermore, we reveal that the natural convection in the atmosphere can be enhanced by radiation in the non-atmospheric window, which increases the total cooling power from 136 W ∙ m−2 to 252 W ∙ m−2 at 150 °C surface temperature. This work may introduce the opportunities for multispectral manipulation, infrared signal processing, thermal management, and energy-efficient applications.

Colorful surfaces for radiative cooling

“…Photonic structural colors received extensive interests in recent decades due to their unique coloration mechanism that is different from conventional pigments. [91][92][93][94][95][96][97][98][99][100] Intriguingly, the color of photonic structures can be designed using engineered subwavelength features to minimize the solar heating effect. For instance, owing to controlled thin film interference (e.g., Fabry-Pérot interference), layered photonic structures can generate designated color within the full visible range.…”

“…4 97 engineered multilayered films [Fig. 4(f)], 98 and metallic nanoparticle resonances. 100 The major target for these works is to realize narrowband optical absorption (i.e., structure-induced colors) and keep the strong thermal emission simultaneously for radiative cooling.…”

“…Photonic structural colors received extensive interests in recent decades due to their unique coloration mechanism that is different from conventional pigments [91][92][93][94][95][96][97][98][99][100]. Intriguingly, the color of photonic structures can be designed using engineered subwavelength features to minimize the solar heating effect.…”

Infrared Camouflage Utilizing Ultrathin Flexible Large‐Scale High‐Temperature‐Tolerant Lambertian Surfaces

“…Besides, thin and light-weighted surfaces with flexibility and high-temperature tolerance are essential for practical infrared camouflage applications. [28,42,53,54] In this work, infrared camouflage was demonstrated using an ultrathin, flexible, large-scale, high-temperature-tolerant Lambertian surface. [55] The Lambertian surface for infrared camouflage presents several distinct advantages: 1) low emissivity (≈0.1), nearly perfect diffuse reflection property over a wide wavelength range (0.75-25 μm), and low specular reflectivity (≈0.05);…”

“…Besides, thin and light‐weighted surfaces with flexibility and high‐temperature tolerance are essential for practical infrared camouflage applications. [ 28,42,53,54 ]…”