@inproceedings{RosenbergerBelleHellmann2009, author = {Rosenberger, Manuel and Belle, Stefan and Hellmann, Ralf}, title = {Optical interrogation of bragg grating sensors using tunable fibre based bandpass filter}, series = {Proceedings of the 20st international science conference, Mittweida}, booktitle = {Proceedings of the 20st international science conference, Mittweida}, year = {2009}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{BelleScheurichHellmann2009, author = {Belle, Stefan and Scheurich, Steffen and Hellmann, Ralf}, title = {Interrogation water content in organic solvents by planar bragg grating sensors}, series = {Proceedings SENSOR}, booktitle = {Proceedings SENSOR}, number = {Vol. II, P3.2}, isbn = {978-3-9810993-6-2}, pages = {324 -- 329}, year = {2009}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{ScheurichBelleHellmannetal.2009, author = {Scheurich, Steffen and Belle, Stefan and Hellmann, Ralf and So, Sik and Sparrow, Ian and Emmerson, Greg}, title = {Application of a silica-on-silicon planar optical waveguide. Bragg grating sensor for organic liquid compound detection}, series = {SPIE Optics an optoelectronics conference, Proceedings of SPIE, Vol. 7356, Prag, CR}, booktitle = {SPIE Optics an optoelectronics conference, Proceedings of SPIE, Vol. 7356, Prag, CR}, number = {7356}, isbn = {978-0819476302}, year = {2009}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{ScheurichBelleHellmannetal.2009, author = {Scheurich, Steffen and Belle, Stefan and Hellmann, Ralf and So, Sik and Sparrow, Ian and Emmerson, Greg}, title = {Planar optical waveguide bragg grating chemical sensor for online process control}, series = {3rd integrated optics - sensors, sensing structures and methodes Korbielow, PL}, booktitle = {3rd integrated optics - sensors, sensing structures and methodes Korbielow, PL}, year = {2009}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{KalmarHellmannRegertetal.2012, author = {Kalm{\´a}r, L{\´a}szl{\´o} and Hellmann, Ralf and R{\´e}gert, Tam{\´a}s and Varga, Zoltan}, title = {Numerical investigation of heat transport procedure in high power LED modules}, series = {Proceedings of the XXVI International MicroCAD Conference, Miskolc (Hungary)}, booktitle = {Proceedings of the XXVI International MicroCAD Conference, Miskolc (Hungary)}, pages = {43 -- 46}, year = {2012}, subject = {Lumineszenzdiode}, language = {en} } @inproceedings{BischoffJaegerRungetal.2012, author = {Bischoff, Christian and J{\"a}ger, Erwin and Rung, Stefan and Hellmann, Ralf}, title = {Diffractive beam shaping optics for efficient micromachining}, series = {Proceedings of the LASYS (Internationale Fachmesse f{\"u}r Laser-Materialbearbeitung) - SLT (Stuttgarter Lasertage) 2012}, booktitle = {Proceedings of the LASYS (Internationale Fachmesse f{\"u}r Laser-Materialbearbeitung) - SLT (Stuttgarter Lasertage) 2012}, year = {2012}, subject = {Laserbearbeitung}, language = {en} } @inproceedings{KollerHesslerRosenbergeretal.2012, author = {Koller, Georg and Hessler, Steffen and Rosenberger, Manuel and Belle, Stefan and Hellmann, Ralf}, title = {Micro-structured optical waveguide fabrication in PMMA using low frequency reactive ion etching}, series = {Proceedings of the XXVI International MicroCAD Conference - Sensing Technologies, Miskolc (Hungary)}, booktitle = {Proceedings of the XXVI International MicroCAD Conference - Sensing Technologies, Miskolc (Hungary)}, year = {2012}, subject = {Wellenleiter}, language = {en} } @inproceedings{GirschikofskyRosenbergerBelleetal.2012, author = {Girschikofsky, Maiko and Rosenberger, Manuel and Belle, Stefan and Brutschy, Malte and Waldvogel, Siegfried and Hellmann, Ralf}, title = {α-Cyclodextrin functionalized planar Bragg grating sensor for the detection of small arene traces in solvamt vapour}, series = {14th international meeting on chemical sensors (IMCS 2012)}, booktitle = {14th international meeting on chemical sensors (IMCS 2012)}, isbn = {978-3-9813484-2-2}, doi = {10.5162/IMCS2012/7.5.1}, pages = {646 -- 648}, year = {2012}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{RungHellmann2012, author = {Rung, Stefan and Hellmann, Ralf}, title = {Laser scribing of metallized transparent conductive oxide - A comparative study using top hat and Gaussian beam profiles}, series = {Proceedings of the XXVI International MicroCAD Conference - Material Processing Technologies}, booktitle = {Proceedings of the XXVI International MicroCAD Conference - Material Processing Technologies}, year = {2012}, subject = {Laserbearbeitung}, language = {en} } @inproceedings{GirschikofskyRosenbergerBelleetal.2012, author = {Girschikofsky, Maiko and Rosenberger, Manuel and Belle, Stefan and Hellmann, Ralf}, title = {Surface modifications of planar bragg grating refractive index sensors for gas detection}, series = {Proceedings of the XXVI International MicroCAD Conference - Sensing Technologies, Miskolc (Hungary)}, booktitle = {Proceedings of the XXVI International MicroCAD Conference - Sensing Technologies, Miskolc (Hungary)}, year = {2012}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{JaegerRaedelBischoffetal.2014, author = {J{\"a}ger, Erwin and R{\"a}del, Ulrich and Bischoff, Christian and Umhofer, Udo and Rung, Stefan and Hellmann, Ralf}, title = {Laser micromachining - parallel processing with multiple top hat beams}, series = {8th International Conference on Photonic Technologies LANE 2014}, booktitle = {8th International Conference on Photonic Technologies LANE 2014}, year = {2014}, subject = {Laserbearbeitung}, language = {de} } @inproceedings{SchwarzRungEsenetal.2020, author = {Schwarz, Simon and Rung, Stefan and Esen, Cemal and Hellmann, Ralf}, title = {Current results on laser-based production of complex optics in glass}, series = {10. Wetzlarer Herbsttagung "Moderne Optikfertigung", 29. - 30. September 2020, Wetzlar}, booktitle = {10. Wetzlarer Herbsttagung "Moderne Optikfertigung", 29. - 30. September 2020, Wetzlar}, year = {2020}, subject = {Laserbearbeitung}, language = {en} } @inproceedings{SchwarzRungEsenetal.2020, author = {Schwarz, Simon and Rung, Stefan and Esen, Cemal and Hellmann, Ralf}, title = {UKP-Prozess mit anschließendem CO2-Laserpolieren zur Fertigung komplexer Optiken}, series = {10. Workshop Laserbearbeitung von Glaswerkstoffen}, booktitle = {10. Workshop Laserbearbeitung von Glaswerkstoffen}, year = {2020}, subject = {Linse}, language = {en} } @inproceedings{SauerKeferRuppertetal.2019, author = {Sauer, Theresia and Kefer, Stefan and Ruppert, Wolfgang and Hellmann, Ralf and Kaloudis, Michael}, title = {Integration of Bragg grating sensors in components made of carbon fiber reinforced polymers}, series = {Tagungsband der 20. GMA/ITG-Fachtagung Sensoren und Messsysteme 2019, 25.06.2019 - 26.06.2019, N{\"u}rnberg, Deutschland}, booktitle = {Tagungsband der 20. GMA/ITG-Fachtagung Sensoren und Messsysteme 2019, 25.06.2019 - 26.06.2019, N{\"u}rnberg, Deutschland}, isbn = {978-3-9819376-0-2}, doi = {10.5162/sensoren2019/P3.12}, pages = {806 -- 810}, year = {2019}, abstract = {This contribution discusses the integration of polymer planar Bragg grating sensors (PPBG) into carbon fiber reinforced polymer (CFRP) components. For the first time, it is shown that PPBGs based on cyclic olefin copolymers can be integrated into commercial-grade composites, thereby withstanding the demanding production processes. Pre-impregnated fibers are stacked and partially modified to form a sensor pocket. Afterwards, the CFRP specimen containing the optical sensor is cured in a heated mechanical press for 2 hours at a pressure of 7 bar and a temperature of 120 °C. A subsequent evalutaion of the sensor signal shows a Bragg wavelength shift of 1236 pm and a decline in signal amplitude of -2 dB. Three-point flexural tests of the cured sample reveal a linear behavior of the sensor signal towards external loads. The determined sensitivity in dependence of the CFRP specimen's maximum central deflection is -112 pm/mm, while correlation to the applied force results in a sensitivity of -5 pm/N.}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{RothEsenHellmann2020, author = {Roth, Gian-Luca and Esen, Cemal and Hellmann, Ralf}, title = {Internal micro structuring of transparent optical polymers by fs laser}, series = {Laser-based Micro-and Nanoprocessing XIV 2020}, volume = {11268}, booktitle = {Laser-based Micro-and Nanoprocessing XIV 2020}, publisher = {International Society for Optics and Photonics}, doi = {10.1117/12.2543487}, pages = {112681L}, year = {2020}, abstract = {Lab-on-chip systems are based on components to transport, mix, separate and analyse small volumes of different fluids. The consecutive integration of more complex functions into a single and compact chip demands on multilayer systems. As the classical production using a stacking and joining of single processed layers is elaborate and limited in terms of multilayer structures, an uprising trend to fabricate those devices is the internal, three dimensional processing of transparent substrates by using ultrashort laser pulses. In this study, we report on the generation of internal hollow architectures created by focused 514nm femtosecond laser pulses inside optical polymer bulk materials of different polymers. The three-dimensional channel layout is implemented by moving the sample using three-dimensional motorized stages, allowing arbitrary complex shaped internal channel architectures. Size and cross sectional shape of a single internal generated microchannel are determined by the intensity distribution of the focal voxel. In particular, we show a comprehensive parameter study to improve this laser process with respect to a higher processing speed and stability.}, subject = {Femtosekundenlaser}, language = {en} } @inproceedings{RothWolfEsenetal.2019, author = {Roth, Gian-Luca and Wolf, Bastian and Esen, Cemal and Hellmann, Ralf}, title = {Generation of internal 3D microfluidic architectures in polymers by fs laser processing}, series = {Lasers in Manufacturing 2019}, booktitle = {Lasers in Manufacturing 2019}, year = {2019}, abstract = {Microfluidic lab on chip systems require components to transport, mix, separate and analyse small volumes of different fluids. In this study, we report on the laser generation of internal hollow architectures created by focused 514 nm femtosecond laser pulses inside PMMA bulk material. Size and cross-sectional shape of a single internal generated microchannel are determined by the intensity distribution inside the focal voxel and can be controlled either by the numerical aperture of the focusing objective or by laser beam shaping. As both approaches are practically limited with respect to the realizable cross-sectional shapes, we present a process based on an internal hatching to expand the achievable channel cross-sections and thereby enable the possibility to create complex 3D shaped internal structures. This process is applied to create fully internal functional microfluidic elements such as mixers which are part of most polymer lab-on-chip systems.}, subject = {Femtosekundenlaser}, language = {en} } @inproceedings{AdelmannHellmann2015, author = {Adelmann, Benedikt and Hellmann, Ralf}, title = {Comparative study of experimentally determined and simulated mechanical strength of fiber laser cut alumina substrates}, series = {Proceedings of the 7th International Congress on Laser Advanced Materials Processing}, volume = {2015}, booktitle = {Proceedings of the 7th International Congress on Laser Advanced Materials Processing}, number = {15}, pages = {1 -- 9}, year = {2015}, subject = {Laserschneiden}, language = {en} } @inproceedings{AdelmannNeumeierSchleieretal.2015, author = {Adelmann, Benedikt and Neumeier, Benedikt and Schleier, Max and Wilmann, Eugen and Hellmann, Ralf}, title = {Optical cutting tear detection system for industrial fiber laser based cutting machines}, series = {Lasers in Manufacturing Conference 2015}, booktitle = {Lasers in Manufacturing Conference 2015}, year = {2015}, subject = {Laserschneiden}, language = {en} } @inproceedings{SchwarzRungEsenetal.2020, author = {Schwarz, Simon and Rung, Stefan and Esen, Cemal and Hellmann, Ralf}, title = {Manufacturing of optical elements by non-contact laser processing}, series = {Seventh European Seminar on Precision Optics Manufacturing, Proceedings}, booktitle = {Seventh European Seminar on Precision Optics Manufacturing, Proceedings}, number = {11478}, year = {2020}, subject = {Laserbearbeitung}, language = {en} } @inproceedings{SchwarzRungEsenetal.2020, author = {Schwarz, Simon and Rung, Stefan and Esen, Cemal and Hellmann, Ralf}, title = {All laser-based fabrication of optical elements}, series = {Proceedings of SPIE 11270, Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XX}, booktitle = {Proceedings of SPIE 11270, Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XX}, year = {2020}, subject = {Ultrakurzzeitlaser}, language = {de} }