Diffuser-Supported Hyperspectral Near-Infrared Measurement for Sensitivity Enhancement in Analysis of Diverse Thin Sheet Samples

Abstract

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 the 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. When the weighing paper, plastic gloves, and mesh fabric sheets (thickness: 20-230 mu m) were measured using a conventional scheme without using the diffuser, peaks corresponding to the sheet samples were difficult to recognize; with the diffuser, they were apparent with enhanced intensity. Furthermore, the increased number of sample-interacting photons when using the diffuser was confirmed by a Monte Carlo simulation. Next, to evaluate its real usage, we attempted to determine the crude protein contents in dried laver sheets (thickness: 210-480 mu m). When the diffuser was employed, peaks centered at 1181 and 1461 nm corresponding to the organic constituents of laver sheets were distinct; these peaks were not observed in the measurement without a diffuser. Due to the peaks with enhanced intensity, the determined crude protein contents were well correlated with those based on conventional Kjeldahl analysis.