By utilizing the absorption, reflection, and scattering effects of infrared light penetrating materials, the system achieves non-contact thickness measurement of film materials. Near-infrared (NIR) light at specific wavelengths (780-2500 nm) is selectively absorbed by C-H or O-H bonds in material molecules, and the absorption amount is directly proportional to the number of molecules containing C-H or O-H bonds. The NIR Basis Weight/Moisture Gauge applies this principle. By using optical detectors to measure the amount of NIR light absorbed after transmitting through or scattering off the material surface, it calculates the basis weight or moisture content of materials containing C-H or O-H bonds. The NIR thickness gauge features no radiation hazard, high measurement stability, and ease of operation.