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Periodične površinske strukture povzročene z nanosekundnim vlakenskim laserjem
Mrzlikar, Žiga (Author), Gregorčič, Peter (Mentor) More about this mentor... This link opens in a new window

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Abstract
Lasersko povzročene periodične površinske strukture (LIPSS) je mogoče izdelati v enem koraku tako na kovinah, kot na polprevodnikih ali dielektrikih. Ker je z njimi mogoče pomembno izboljšati funkcionalnost površin, so predmet številnih raziskav. V nalogi smo nanosekuni vlakenski laser s spremenljivo dolžino bliskov in valovno dolžino 1060 nm nadgradili s polarizatorjem. Pokazali smo, da je na ta način mogoče izdelati LIPSS brez uporabe dragih laserskih sistemov z ultrakratkimi bliski, kar pomembno širi možnosti za implementacijo tovrstnega laserskega mikrostrukturiranja na različna industrijska področja. Z laserjem smo osvetljevali nerjavno jeklo in določili fluenco praga za ablacijo, ki v našem primeru znaša 3,7 J/cm2. Raziskali smo tudi, kako različne smeri označevanja, povprečna moč bliskov in pozicija obdelovanca glede na gorišče laserskega snopa vplivajo na nastanek LIPSS. Rezultati kažejo, da LIPSS nastane, ko fluenca v sredini pasu laserskega snopa doseže vrednosti med 0.9 in 1.4 kratnikom fluence praga za ablacijo. Pri tem so nastale površinske strukture s periodo okoli valovne dolžine. V večini primerov so bile neodvisne od smeri označevanja, so se pa ob določeni kombinaciji parametrov pojavile tudi izjeme, kjer so bile strukture vzporedne s smerjo označevanja. Pokazali smo tudi, da so nastale periodične strukture bolj izrazite, če vzorec izmaknemo iz gorišča. Na koncu smo ovrednotili tudi barve, ki se na površini pojavijo zaradi LIPSS. Ključna ugotovitev naloge je, da je tudi nanosekundni vlakenski laser mogoče uporabiti za funkcionalizacijo površin z LIPSS, kar odpira nove možnosti za tehnološki preboj na številnih področjih, kjer je cena obdelave površin ključnega pomena.

Language:Slovenian
Keywords:LIPSS lasersko mikrostrukturiranje vlakenski laser funkcionalizacija površin periodične površinske strukture
Work type:Bachelor thesis/paper (mb11)
Organization:FS - Faculty of Mechanical Engineering
Year:2017
Views:735
Downloads:569
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Secondary language

Language:English
Title:Periodic surface structures induced by a nanosecond fiber laser
Abstract:
Laser-induced periodic surface structures (LIPSS) can be produced in a single step on metals, semiconductors or dielectrics. Since they allow a significant improvement of the surface functionalities, they are a subject of an intensive research. In this thesis, we used a nanosecond fiber laser having variable pulse duration and a wavelength of 1060 nm. We upgraded the laser system by a polarizer to demonstrate that in this way it is possible to obtain LIPSS without the use of expensive ultrashort laser systems. This new approach will significantly expand the possibilities for implementation of this kind of laser microstructuring into different industrial areas. By pulses we irradiated the stainless steel. Firstly, we measured the fluence threshold for material ablation; in our case it equals 3,7 J/cm2. Then, we examined how different marking directions, the average laser power and the position of the sample out of the focal position influence the LIPSS formation. The results show that LIPSS occurs when the peak fluence is within 0.91.4 times of the threshold for material ablation. In this case, LIPSS has a period roughly equal to the laser wavelength. In most cases LIPSS orientation does not depend on the texturing direction. However, there are certain parameters where LIPSS orientation changes with the texturing direction. We have also shown that the periodic structures are more pronounced when the sample is positioned slightly out of the focus. As an example of surface functionalization, we evaluated the colors appearing on the surface due to LIPSS. A key thesis conclusion is the proof that a nanosecond fiber laser can also be used to functionalize the surfaces with LIPSS. This opens up new possibilities for technological breakthroughs in many areas where the costs of surface processing are of key importance.

Keywords:LIPSS laser microstructuring fiber laser surface functionalization periodic surface structures

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