Research On Imitation Plant Leaf Material Based On Hyperspectral Detection

As a new generation of"image and spectral fusion"photoelectric detection technology,hyperspectral remote sensing detection can identify the slight difference between the target and the background spectral characteristics,which makes military targets seriously threatened.Traditional optical/infrared stealth materials basically do not have the stealth function under hyperspectral detection technology.Aiming at the common green vegetation in the background of ground objects,this thesis studies the characteristics of the solar spectral reflectance curve of plant leaves and the influence of leaf biochemical components on it.Based on this theoretical guidance,a kind of biomimetic camouflage material was designed and prepared with polyvinyl alcohol PVA hydrogel as the main body and chromium oxide(Cr₂O₃)as the green pigment,which can simulate the solar spectral reflectance characteristics of green leaves,and its spectral simulation effect is evaluated,showing that the material spectrum has a high degree of similarity with the green leaf spectrum.In order to understand the spectral characteristics of plant leaves,the reflectance spectra of various plant leaves were studied in this thesis,and their reflectance spectra show four basic characteristics,including"green peak"near 550nm,"red edge"at680?780nm,"near-infrared plateau"at 780?1300nm and"water absorption peaks"near1430nm and 1930nm.Moreover,the spectra have the characteristics of consistency,and the change of chlorophyll and water content will significantly affect the reflectance spectrum characteristics and intensity of plant leaves.In order to elucidate the key factors affecting the spectral characteristics of plant leaf reflectance,the chlorophyll content and water contents of various plant leaves were extracted and measured,and by using the spectral indices Carter2,GM,Lic3,NDVI,Vog1,Vog2,Vog3 values and the leaf radiative transfer model PROSPECT,the chlorophyll content and water content of leaves were obtained by inversion,and their reliability was checked by comparing the measured and inversion values.Among them,the inversion correlation coefficient of spectral index GM is the largest,which is 0.7982;the inversion correlation coefficient of water content is 0.6059.The results indicated that the method based on spectral index and radiative transfer model PROSPECT could well invert leaf chlorophyll content and water content,which provided theoretical guidance for the design of leaf-like materials.Based on the fact that chlorophyll and water are the main factors affecting the spectral characteristics of plant leaves,a kind of imitation leaf material was designed and prepared with polyvinyl alcohol PVA as the main body and Cr₂O₃ as the green pigment,and the effects of KOH,Cr₂O₃ content and holding time on the spectral reflectance characteristics of imitation leaf materials were studied.The experimental results show that the spectral correlation coefficient between the spectrum of the imitation leaf material prepared by using PVA1799 as the main body,boric acid as the cross-linking agent,adding KOH and Cr₂O₃ and the spectrum of the green leaf is maintained between 0.82and 0.85,and in the 400?2500nm band,the spectral curve of the material can well enter the GJB spectral channel,indicating that the prepared material can basically achieve"same color and same spectrum"with green leaves,and has good hyperspectral stealth ability.