NIR rays absorbed by some bonds, reflected by other bonds (NIR Reflectance) or transmitted through a sample (NIR Transmission generally termed NIT)
The scattered reflected and/or transmitted rays of each wavelength are concentrated onto a measuring cell. A number of reflections at different wavelengths are measured and then converted to analytical results by a microprocessor.
There is often a misunderstanding of the term NIR Reflectance. The rays are not merely reflected from the outside surface, but actually penetrate the sample. Each time a chemical bond is encountered that does not absorb the particular wavelength, the rays are scattered and reflected in all directions. These scattered beams may then be absorbed or reflected by other chemical bonds until a portion of the rays eventually exits the sample in all directions (Figure 5). The depth of penetration of the beam into the sample is not determined by the position of the detector, but rather by the strength of the light source.