Primena laserskih tehnika za određivanje optičkih parametara materijala
Committee membersOstojić, Stanko
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The influence of stimulated electromagnetic radiation in optical part of spectra (visible, UV and IR) to materials is for almost half a century the issue of research including a lot of unexplained processes and stances. From one point of view represents new form of source and from the other the relation to spontaneous sources in the same spectral area as well as the power. The issues could be divided into theoretical-experimental processes from biomodulation to destruction and to the area where coherent radiation is used in diagnostic methods for material study. In this thesis the subject was approached from theoretical-experimental side. The observation of materials was forwarded trough material response functions, meaning trough their collective role expressed using optical characteristic materials. In experimental part of the thesis a series of experiments was conducted, determining certain optical parameters for chosen samples along with spectroscopic approach. That woul...d be the first approach for following series of experiments in which plant samples namely seeds (wheat, corn, spinach, basil, thyme) where axposed to various types of laser beams (He-Ne, Nd3+:YAG, semiconductor) on basic transitions and according to laser possibilities at higher harmonics. The results of sample irradiation with given parameters, were monitored until the end of vegetation periods. The morphological characteristic of irradiated and nonirradiated samples were monitored as well as quantitative indicators of induced modifications. In given area of energy densities and exposition doses, almost all samples shown positive influence of coherent radiation. For some of the samples a change in FT-IR spectra was observed. For use of lasers in main processes, occurring in metrology where linear and nonlinear characteristics of materials occurs, scattering, absorption and fluorescence of materials including materials of the live world (tissue, cells and their parts). These processes are observed and used for optical defining of objects, and from their values (characteristic) and from wavelength of the used light depends which effect will overcame including resonance. In the area of techniques based on static and dynamic scattering angular distributions play a considerable role in determination of objects by size and shape. So in this thesis, using chosen software, a number of angular distribution simulations was done for microorganisms, typical particles and water. Given approach could using data bases or newly measured values, without modifications, be used for other adequate samples, simplifying the experiments in advance including characteristic maxima at certain angles for chosen samples. Ecological side of laser application viewed through accidental (fire) processes contains multitude of approaches from use of lidars to sensory role of much simpler systems. In this thesis the approaches to monitoring of certain area (ground, earth, different covers, water areas, atmosphere phenomena) are perceived trough analysis of possible remote devices lidar based. It’s a principal including fire processes here analyzed, searching for possibilities of software support, covering certain experimental settings. The nature of combustion products could be also viewed by simulation of scattering processes (propane and acetylene sooth).