Hyperspectral Near-infrared Spectroscopy for Compositional Analysis of Large-thin Sheets and High-throughput Discriminant Analysis of Multiple Samples

A diffuser-supported hyperspectral near-infrared (DS-HS-NIR) measurement scheme in which a Teflon plate as a photon diffuser was placed beneath a thin sheet sample for trans-reflectance spectral acquisition was proposed to enhance peak intensity (sensitivity) of the sample. The scheme was to increase the number of sample-interacting photons by generating diffused photons using a Teflon (diffuser) and directing them toward a spectroscopic sampling area to additionally interact with a sample, increasing the intensity of the subsequent peak. The utility of this scheme was examined with measuring the weighing paper, plastic gloves, and mesh fabric sheets, and also laver sheets to determine their crude protein contents. Further, HS-NIR spectroscopy was exploited first to discriminate (i) beaded salt water-cultured (B-SW), (ii) beaded fresh water-cultured (B-FW), (iii) non-beaded fresh water-cultured (NB-FW), and (iv) imitation pearls. The distinction of B-SW, B-FW, and NB-FW pearls was feasible since their NIR spectra were dissimilar depending on the characteristics of pearls such as chemical composition, irradiance (orient), and gloss. The F1 scores identifying the imitation, B-SW, B-FW, and NB-FW pearls were 100, 95.6, 96 and 100%, respectively, and the overall prediction accuracy was superior, 97.9%.