Infrared (IR) camouflage, which is used to conceal objects in infrared vision for confrontation with infrared detection in civilian and military applications, is gathered interest increasingly. Here, the tunable selective emitter depended on temperature is proposed. When the temperature is below 341K, the emitter has low emissivity in 3-5μm and 8-14μm, and high emissivity in 5-8μm. The bandwidth with the emissivity above 50% is 3μm; With the temperature above 341K, the average emissivity in 3-14μm is 0.23, which can achieve excellent infrared camouflage. The maximum modulation depth of emissivity is 51.56%. It is believed that the emitter can explore further applications in thermal management, adaptive thermal camouflage and energy harvesting.
The Fatamogana Mirage is a complex and changeable mirage that forms in a special environment.Starting from the formation environment of Fatamoogana, we construct the medium system of refractive index gradient change, conduct simulation experiments, and reproduce the process and scene of Fatamoogana formation, and the characteristics of the mirage and the propagation of the light in refractive index gradient are analyzed.Subsequently, based on the propagation process and mechanism of light in a variable refractive index gradient medium, starting with the monotonic changing media environment of the refractive index, this paper establishes a variety of medium change gradient models, solving the path equation of light according to the infinitesimal element method , then, using symmetric principles and classification discuss ideas,the paper establishes the propagation path model of light in a complex index gradient medium, and the light path propagation equation is calculated through the model.On this basis, the paper analyzes the propagation characteristics of light in complex refractive index gradient media, and the mathematical relationship between the observer, mirage source and mirage is calculated, which explains the reasons for the complex and changeable nature of Fatamogana mirage.Finally, the paper analyzes the significance of research results in the design of laser aiming system and radio communication communication.
In this paper, we proposed an infrared absorber based on multilayer film. Through the thickness resonance of ZnS dielectric layers and the loss properties of ultra-thin titanium film, a good absorption is achieved in the infrared band. The outermost ZnS is employed to reduce impedance mismatch and protects ultra-thin Ti film. This sample does not need inplane microstructure design, which reduces the processing difficulty and can be prepared on large scales.
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