Bionic membrane simulating solar spectrum reflection characteristics of natural leaf

摘要

Hyperspectral imaging is becoming an important detection method, which can identify the subtle differences between the reflection spectra of a target and its background. Considering that vegetation is one of the most important backgrounds, a bionic membrane containing hygroscopic material and chromium sesquioxide (Cr_2O_3) pigment was prepared to counter the hyperspectral detection through simulating the solar spectrum reflectance of natural leaf. The effects of water and Cr_2O_3 contents on the reflectance of the bionic membrane were discussed, and the absorption and scattering coefficients of the bionic membrane were calculated via a four-flux model to elucidate its reflection mechanism. Based on the obtained absorption and scattering coefficients, the reflectances of the bionic membranes (with a volume fraction of water in the range of 9.75-51.92% during the day time) containing different volume fraction of Cr_2O_3 (f_c) were calculated through the four-flux model. Besides, a military specification of USA was used as the spectrum requirement of the bionic membrane in our work to determine an appropriate Cr_2O_3 content. It was found that when f_c is 1.61%, the reflection spectra of the 3 mm thick bionic membranes can not only meet the military specification but also become opaque, which are capable to camouflage a target.