Optical properties of cotton and mulching film and feature bands selection in the 400 to 1120 nm range

Abstract

Cotton is prone to being mixed with mulching film during the harvesting and packing process in China, which can significantly decrease the quality of cotton fiber and impact the quality of subsequent textile products. Mulching film is a translucent material that makes it challenging to detect optically, which presents an urgent challenge for cotton quality testing due to the lack of research on its detection mechanism. In this study, the absorption coefficient (μa), reduced scattering coefficient (μs'), and scattering anisotropy factor (g) of cotton lint and mulching film in the spectral region of 400–1120 nm were obtained using an integrating sphere-based spectroscopic measurement system. The accuracy of the system was validated using liquid phantoms made from polystyrene particles and absorbing dyes. The interval random frog (iRF) algorithm was used to select feature bands, and multivariate analysis of variance (MANOVA) was employed to assess the differences between cotton and mulching film in terms of μa and μs' in the selected feature bands. Support vector machine (SVM) and linear discriminant analysis (LDA) were utilized to classify the concatenation of μa, μs', μa and μs' of cotton and mulching film in full wavelengths and feature bands. The results demonstrated that there were significant differences in μa, μs' and g between cotton and mulching film due to their different chemical compositions, surface morphology, and tensile properties. The selected feature bands were in the blue band (456.1 nm), red bands (605.8 nm, 628.9 nm, 685.6 nm), and near-infrared bands (805.4 nm, 837 nm, 1006.3 nm). The SVM classification results of the concatenation of μa, μs', μa and μs' for cotton and mulching film were 100 % in both full wavelengths and feature bands. This study makes a significant contribution by reporting the optical properties of cotton and mulching film, which were used to determine the detection sensitive bands. These findings will serve as a theoretical foundation and data set for the development of detection equipment to identify mulching film in the cotton production process.