Multispectral compatible camouflage with thermal management based on a multilayer thin film structure.

Area of Science:

• Materials Science
• Optics
• Thermal Engineering

Background:

• Effective camouflage requires adapting to visible backgrounds and managing thermal signatures.
• Existing camouflage technologies often lack multispectral compatibility and efficient thermal management.

Purpose of the Study:

• To propose a multispectral camouflage device with integrated thermal management capabilities.
• To demonstrate tunable structural color for visible spectrum adaptation.
• To achieve low emissivity in atmospheric windows and high emissivity in specific non-atmospheric windows for radiative cooling.

Main Methods:

• Fabrication of a seven-thin-film device using five materials: Silicon (Si), Germanium (Ge), Silicon Dioxide (SiO2), Ge2Sb2Te5 (GST), and Aluminum (Al).
• Analysis of structural color control via top Si layer thickness for visible spectrum camouflage.
• Measurement of spectral emissivity in infrared atmospheric windows (3-5 μm and 8-14 μm) and non-atmospheric windows (5-8 μm).
• Evaluation of radiative cooling power and camouflage performance against laser radar frequencies (1.06 μm, 1.55 μm, 10.6 μm).

Main Results:

• Tunable structural color achieved by altering the top Si layer thickness for visible spectrum camouflage.
• Low average emissivity of 17.7% (3-5 μm) and 23.0% (8-14 μm) in infrared atmospheric windows.
• High emissivity of 65.7% in the 5-8 μm window, enabling net radiative cooling power of 500 W/m².
• Narrowband high emissivity achieved at laser radar frequencies (81.3% at 1.06 μm, 84.8% at 1.55 μm, 81.4% at 10.6 μm).
• Excellent angular and polarization insensitivity demonstrated.

Conclusions:

• A simple film structure can achieve multispectral camouflage and efficient thermal management.
• Coordinated control of electromagnetic waves and heat is feasible.
• The device has significant implications for industrial manufacturing and military camouflage.