An instrument using the near-infrared reflectance technique was designed to measure surface moisture on porous materials. The basic instrument design consists of a radiation source, a lens system, narrow-band interference filters, a detector, and a data acquisition system. The instrument function, operation, and calibration are discussed in detail. The modified Kubelka-Munk function is used for the data transformation. The experimental data from glass beads of 65, 120, and 450 #x3BC;m in diameter show that a two-point linear model can be utilized for calibration. The instrument uncertainty is estimated to be less than #xB1;6.2.
展开▼
