Upodabljanje velikih količin letalskih podatkov LiDAR : doktorska disertacija

slovenian

doktorska dela

2014

algorithms   computer science   hybrid rendering   point-based rendering   render-to-texture   surface detection   terrain visualization

Univerza v Mariboru, Fakulteta za elektrotehniko računalništvo in informatiko

330a This dissertation presents the optical fibers, which can be effective and all-optical heated. The heating of the fiber is caused by thermo-optics effect which can be efficiently used to build various thermo-optical devices. Such fibers have a core doped with standard dopands for refractive index control, and with vanadium. The vanadium as a dopand within the optical fiber's core causes high absorption of light with shorter wavelengths and has an absorption peak of around 980 nm. The absorption at longer wavelengths like standard telecommunication wavelengths having 1310 nm and especially 1550 nm remains relatively low. These allow for the use of standard and widely available commercial pump diodes that have high output optical powers and wavelengths of around 980 nm, and are generally used for pumping the fiber amplifiers or fiber lasers. The absorbed light with a wavelength of 980 nm is thus fully converted into heat via a non-radiative process which raises the fiber's temperature. The change in temperature causes a change in the fiber's refractive index, which leads to optical path-length change. Thus the optical path length change can be controlled through the heat diode output optical power control. The total change in optical path difference and the time constant of the system depends on the thermal conductivity of the surrounding fluid, and on the heated fiber's diameter, whilst the total change in optical path difference also depends on the heated optical power. This all-optical thermo-optical modulator was presented in practice by utilizing a 500 mW, 980 nm pump-diode for the vanadium-doped fiber heating. A total change in optical path difference in excess of 1 mm and a time constant of 11 ms were demonstrated in practice. The presented modulator was further used as a scanning interferometer within a white light interferometer. The total change in optical path length and the time constant of the heated fiber depends on the thermal conductivity of the surrounding fluid. It is therefore possible to realize a measurement system for thermal conductivity measurement by the monitoring of one or both parameters. The presented measurement systems is based on time constant measurement of the heated optical fiber, and allows for gas distinguishing, the measurements of the mass ration in binary mixtures with a measurement resolution of 0,3 % and a vacuum measurement within the pressure range from 10-2 mBar up to 1 Bar. This measurement system utilizes standard telecommunication electro-optics components and presents a complete solution for thermal conductivity measurements and for thermal conductivity-related physical quantity measurements.

07.08.2023