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Darmstadt, Germany

Rung S.,University of Applied Sciences Aschaffenburg | Rexhepi M.,University of Applied Sciences Aschaffenburg | Bischoff C.,TOPAG Lasertechnik GmbH | Hellmann R.,University of Applied Sciences Aschaffenburg
Journal of Laser Micro Nanoengineering | Year: 2013

We present a comparative study of laser scribing different thin solid films using nanosecond la-ser pulses with different wavelengths and laser beam profiles. In particular, we show the influence of the used laser beam profile for the processing of a 150nm thin Indium Tin Oxide transparent con-ductive film and a multilayer system, consisting of different metal and transparent conductive oxide (TCO) layers deposited on a soda lime glass substrate. For laser scribing the wavelengths 1064nm, 532nm and 355nm were used with a Gaussian and a Top-Hat beam profile. The homogenous Top-Hat beam profile is generated with both, a refractive and diffractive beam shaper. The results show several advantages of using a Top-Hat laser beam shape for thin film laser scribing, such as less en-ergy consumption, high rim quality with simultaneous small pulse overlap and protection of the un-derlying substrate, respectively. Our results prove that the application of beam shapers can improve the process quality and increase the scribing speed for the investigated materials.


Schmitt J.,RheinMain University of Applied science | Schmitt J.,Albert Ludwigs University of Freiburg | Bischoff Ch.,TOPAG Lasertechnik GmbH | Radel U.,TOPAG Lasertechnik GmbH | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Shaping of laser light intensities by using Diffractive Optical Elements allows the adaption of the incident light to its application. Fused silica is used where for example UV-light or high temperatures are mandatory. For high diffraction efficiency the quality of the etched surface areas is important. The investigation of different process parameters for Ion Beam and Reactive Ion Etching reveals that only Ion Beam Etching provides surfaces with optical quality. Measurements of the influence of the surface quality on the diffraction efficiencies prove that the surfaces generated by Reactive Ion Etching are not suitable. Due to the high selectivity of the process Reactive Ion Etching is nevertheless a reasonable choice for the fabrication of Diffractive Optical Elements. To improve the quality of the etched surfaces a post processing with Ion Beam Etching is developed. Simulations in MATLAB display that the angle dependent removal of the surface during the Ion Beam Etching causes a smoothing of the surface roughness. The positive influence of a post processing on the diffraction efficiency is outlined by measurements. The ion beam post processing leads to an increase of the etching depth. For the fabrication of high efficient Diffractive Optical Elements this has to be taken into account. The relation is investigated and transferred to the fabrication of four-level gratings. Diffraction efficiencies up to 78 % instead of the ideal 81 % underline the practicability of the developed post processing. © 2015 SPIE.


Wolz M.,GD Optical Competence GmbH | Blocher U.,GD Optical Competence GmbH | Dross G.,GD Optical Competence GmbH | Schmitt J.,Wiesbaden University of Applied Sciences | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Laser beam shaping elements can be used e.g. for material processing. The results of these processes can be improved when the usually Gaussian profile of the laser is transformed into a top hat profile, which can be circular or rectangular in shape. Another frequently used type of beam-forming devices are beam splitters for parallel processing using only one laser. These types of beam formers can be implemented as diffractive or refractive elements. So far these optics are produced either directly by means of lithography e.g. in glass or in plastic using a hot embossing process or nanoimprint technology..Elements produced in this way have either the disadvantage of high costs or they are limited in temperature range, laser power or wavelength. A newly developed molding process for glass allows the manufacture of larger numbers of optics with reduced cost. The production of molds for refractive top hat beam shaping devices requires very high precision of the applied grinding process. Form deviations below 100 nm are necessary to obtain a homogeneous illumination. Measurements of the surface topography of gauss to top hat beam shaping elements using white light interferometry are presented as well as results of optical measurements of the beam profile using a camera. Continuous diffractive beam shaping elements for beam splitting applications are designed to generate several sub-beams each carrying the same energy. In order to achieve this, form deviations of less than 50 nm are required. Measurements of the surface of a 1 x 5 beam splitter are compared with ideal beam splitter profiles. The resulting beam intensity distribution of a molded element is presented. © 2015 SPIE CCC.


Rung S.,University of Applied Sciences Aschaffenburg | Bischoff C.,TOPAG Lasertechnik GmbH | Umhofer U.,TOPAG Lasertechnik GmbH | Hellmann R.,University of Applied Sciences Aschaffenburg
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

For thin film ablation one can often not take full advantage of the relatively high output power and high pulse energy of lasers. A solution might be the use of parallel processing technique with multiple beams which help to increase process speed and to save process costs. Within this contribution we demonstrate thin film scribing of GZO and ITO which shows the potential of parallel processing combined with Top-hat beam shaping. The beam shaping optic provides process optimized beam profiles leading to a more efficient process and an improved ablation quality. © 2014 SPIE.


Raciukaitis G.,Lithuanian Academy of Sciences | Stankevicius E.,Lithuanian Academy of Sciences | Gecys P.,Lithuanian Academy of Sciences | Gedvilas M.,Lithuanian Academy of Sciences | And 4 more authors.
Journal of Laser Micro Nanoengineering | Year: 2011

Laser beam shaping and homogenization techniques are substantial to optimize a large number of laser-material processing applications and laser-material interaction studies. Diffractive optical elements (DOE) play important role in provision of the process-adapted laser beam shaping. In this paper, we present an approach for laser beam shaping by using innovative DOE. The circular Gaus-sian beam was transformed to a square flat-top intensity profile in the focal plane of the objective lens by using novel DOE from TOPAG Lasertechnik GmbH. About 95% of the laser energy was coupled in the main beam with a nearly perfect rectangular shape. Experimental results have been achieved by applying the shaped beam for laser microfabrication. The picosecond and nanosecond lasers with moderate beam quality (M2=1.5) were used in the experiment. The shaped laser beam was applied for direct laser ablation of metal film on the glass substrate, drilling in a silicon wafer, scribing of thin-film solar cells and other technical materials. This technique allows creating a rec-tangular-shaped flat-top intensity profile in the focal plane that shows distinct advantages in laser material processing.

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