Production and Characterization of Femtosecond-Laser-Induced Air Plasma

<p>The purpose of this research was to produce characterize and optimize laser-induced air plasma as a preliminary step in using theplasma as a source of terahertz radiation. An 800 nanometer 50 femtosecond 0.75 Watt pulsed Ti:Sapphire laser system was usedas the source infrared beam. A beam expander was used to expand the beam to a diameter of approximately 6.5 mm and the beamwas focused through a 25 mm focal length achromatic lens to produce laser-induced plasma in ambient air. A 40 kHz ultrasonictransducer was used to detect the plasma. A second harmonic generation crystal was placed within the beam expander to generate400 nm blue light enabling production of THz in the plasma via four wave mixing; a third-order nonlinear process. Whileplasma-produced THz was not detected all the preliminary groundwork was accomplished including full characterization of theplasma blue light and alignment of the system to generate and detect THz. The electro-optic detection apparatus was assembledaligned and used to successfully detect a diagnostic THz signal.</p><p>This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it. This work was reproduced from the original artifact and remains as true to the original work as possible. Therefore you will see the original copyright references library stamps (as most of these works have been housed in our most important libraries around the world) and other notations in the work.</p><p>This work is in the public domain in the United States of America and possibly other nations. Within the United States you may freely copy and distribute this work as no entity (individual or corporate) has a copyright on the body of the work.</p><p>As a reproduction of a historical artifact this work may contain missing or blurred pages poor pictures errant marks etc. Scholars believe and we concur that this work is important enough to be preserved reproduced and made generally available to the public. We appreciate your support of the preservation process and thank you for being an important part of keeping this knowledge alive and relevant.</p>