Contactless investigation of porous materials with the aid of He–Ne laser radiation

An experimental investigation was made of the water content of porous materials, which affects physical, physicochemical, and chemical processes. The investigation was based on the fact that water vapour and drops present in the pores of a material can influence the scattering of light by its surface when it is illuminated with a narrow low-intensity laser beam. Measurements were made of the intensity of He–Ne laser radiation reflected by the surface of a moist material (moist gypsum slurry with an internal structure of different types). The scattered-light intensity increased on reduction of the water content of porous materials.