DETERMINATION OF ZONES WITH DIFFERENT CHEMICAL COMPOSITION ON REMOTE SURFACES

• Published in: Nauchno-tekhnicheskiĭ vestnik informat͡s︡ionnykh tekhnologiĭ, mekhaniki i optiki mekhaniki i optiki, 2017-09, Vol.17 (5), p.812
• Main Authors: Demin, S A, Shalobaev, E V
• Format: Article
• Language: Russian
• Subjects: Absorption spectra; Absorptivity; Cameras; Chemical composition; Contamination; Defects; Heat detection; Laser beams; Lasers; Mathematical analysis; Reagents; Surface chemistry; Temperature distribution; Thermal imaging
• ISSN: 2226-1494; 2500-0373
• DOI: 10.17586/2226-1494-2017-17-5-812-819

Subject of Research. A new method of thermal imaging spectroscopy is presented giving the possibility to determine the chemical composition of defects formed as a result of the surface exposure by chemical, biochemical reagents, point contamination of the surface by biological organisms far from the operator in hard-to-reach places where there is no possibility for application of the known optical and spectroscopic equipment. Method. The surface study is performed by thermal imaging camera with simultaneous irradiation of the surface by laser radiation with a wavelength that coincides with the spectral absorption region of the defect substance. The presence of a defect on the surface is determined on the screen of the thermal imaging camera as a zone of contrast between the background temperature and the defect temperature. When the wavelength of the laser radiation coincides with the region of the characteristic absorption band in the absorption spectrum of the defect matter, it becomes possible to determine the chemical composition of the defect. Main Results. A mechatronic module for laser beam scanning over a surface is developed. Simultaneous measurement of the temperature field with the help of a thermal imager and feedback makes it possible to carry out work on the search for zones with the supposed presence of certain zones with definite chemical composition. Experimental results of the defects study are presented with different values of absorption coefficient applied on the heavyweight paper surface in the form of thick drop-shaped layers. A comparative analysis of the experimental and calculated values is carried out. The experiment scheme and the mechatronic complex structure are presented. Practical Relevance. The proposed method can be used to determine contamination spots on the surface of reservoirs, to search for material evidence on unfolded surfaces in forensic examination, to determine the sites of the surface contamination by biological objects during mycological examinations.