Ralf Hellmann, Prof. Dr.
Professor Studiengang Elektro- und Informationstechnik

Telefon: +49 6021/4206-874
Fax: +49 6021/4206-801
Ralf.Hellmann@th-ab.de

Raum: C1/24/104

Sprechzeiten

Dienstag, 15:45-16:45 Uhr

Lehrgebiete

Physik
Werkstofftechnik
Halbleitertechnologie
Lasertechnik

Fachgebiete

Physik
Werkstofftechnik
Halbleitertechnologie
Lasertechnik

Veroeffentlichungen

  • Sauer, Theresia, Kefer, Stefan, Ruppert, Wolfgang, Hellmann, Ralf, Kaloudis, Michael, 2019. Integration of Bragg grating sensors in components made of carbon fiber reinforced polymers. In: Tagungsband der 20. GMA/ITG-Fachtagung Sensoren und Messsysteme 2019, 25.06.2019 - 26.06.2019, Nürnberg, Deutschland. S. 806 – 810. ISBN 978-3-9819376-0-2. Volltext verfügbar unter
  • Preusch, Florian, Rung, Stefan, Hellmann, Ralf, 2016. Influence of Polishing Orientation on the Generation of LIPSS on Stainless Steel. In: Journal of Laser Micro/Nanoengineering. 2016(11), S. 137 – 142.
  • Adelmann, Benedikt, Hellmann, Ralf, 2014. Investigation on Flexural Strength Changes of Alumina Caused by Cutting using Fiber Laser. In: Journal of Laser Micro/Nanoengineering. 9(2), S. 153.
  • Rung, Stefan, Christiansen, Anne, Hellmann, Ralf, 2014. Influence of film thickness on laser ablation threshold of transparent conducting oxide thin-films. In: Applied Surface Science. S. 347 – 351.
  • Rung, Stefan, Bischoff, Christian, Jäger, Erwin, Umhofer, Udo, Hellmann, Ralf, 2014. Laser thin film ablation with multiple beams and tailored beam profiles. In: Proceedings of SPIE 8967, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XIX.
  • Rung, Stefan, Barth, Johannes, Hellmann, Ralf, 2014. Characterization of Laser Beam Shaping Optics Based on Their Ablation Geometry of Thin Films. In: Micromachines. 5(4), S. 943 – 953.
  • Jäger, Erwin, Rädel, Ulrich, Bischoff, Christian, Umhofer, Udo, Rung, Stefan, Hellmann, Ralf, 2014. Laser micromachining – parallel processing with multiple top hat beams. In: 8th International Conference on Photonic Technologies LANE 2014.
  • Adelmann, Benedikt, Hellmann, Ralf, 2013. Process optimization of laser fusion cutting of multilayer stacks of electrical sheets. In: International Journal of Advanced Manufacturing Technology. S. 2693 – 2701.
  • Hasenstab, Stefan, Adelmann, Benedikt, Hellmann, Ralf, 2013. Laser Cutting of Alumina and Aluminum Nitride with a 500 W Single Mode Fiber Laser. In: XXVII. microCAD International Scientific Conference.
  • Adelmann, Benedikt, Hürner, Andreas, Schlegel, Tobias, Bauer, Anton, Frey, Lothar, Hellmann, Ralf, 2013. Laser Alloying Nickel on 4H-Silicon Carbide Substrate to Generate Ohmic Contacts. In: Journal of Laser Micro/Nanoengineering. 8(1), S. 97 – 101.
  • Hürner, Andreas, Schlegel, Tobias, Adelmann, Benedikt, Mitlehner, Heinz, Hellmann, Ralf, Bauer, Anton, Frey, Lothar, 2013. Alloying of Ohmic Contacts to n-type 4H-SiC via Laser Irradiation. In: Materials Science Forum. S. 773 – 776.
  • Adelmann, Benedikt, Hellmann, Ralf, 2013. Investigation on Flexural Strength during Fiber Laser Cutting of Alumina. In: Physics Procedia. S. 405 – 407.
  • Rung, Stefan, Rexhepi, Mal, Bischoff, Christian, Hellmann, Ralf, 2013. Laserscribing of thin films using top-hat laser beam profiles. In: Journal of Laser Micro/Nanoengineering. 8(3), S. 309 – 314.
  • Rung, Stefan, Rexhepi, Mal, Hellmann, Ralf, 2013. Beam shaping for enhanced through-put of laser ablation of transparent conductive films. In: Proceedings of the XXVII MicroCAD International Scientific Conference.
  • Heilmann, Eva-Maria, Kowalski, Thomas, Hellmann, Ralf, Teigelkötter, Johannes, 2012. Water Jet Guided Laser Cutting of High Temperature Superconductors. In: Journal of Laser Micro- and Nanoengineering. 8(1), S. 70 – 74.
  • Hellmann, Ralf, Gockel, Tilo, 2012. Optische Charakterisierung von Leuchtdioden. In: Zeitschrift ELEKTOR, Sonderheft LED-Special 4 – Leuchtdioden in Theorie und Praxis, 2012. 9, S. 40 – 46.
  • Kalmár, László, Hellmann, Ralf, Régert, Tamás, Varga, Zoltan, 2012. Numerical investigation of unsteady heat transport procedure in high power LED module. In: GEP. S. 43 – 46.
  • Schneider, Johannes, Bochtler, Ulrich, Hellmann, Ralf, Kaloudis, Michael, Gockel, Tilo, 2012. LUVLED III – Optimierung eines Kühlkonzeptes zur Aktivluftkühlung eines Hochleistungs-UV-LED-Moduls. In: Zeitschrift ELEKTOR, Sonderheft LED-Special 4 – Leuchtdioden in Theorie und Praxis, 2012. 9, S. 20 – 29.
  • Hock, Klaus, Adelmann, Benedikt, Hellmann, Ralf, 2012. Comparative study of remote fiber laser and water-jet guided laser cutting of thin film metal sheets. In: Physics procedia. S. 225 – 231.
  • Kalmár, László, Hellmann, Ralf, Régert, Tamás, Varga, Zoltan, 2012. Numerical investigation of heat transport procedure in high power LED modules. In: Proceedings of the XXVI International MicroCAD Conference, Miskolc (Hungary). S. 43 – 46.
  • Bischoff, Christian, Jäger, Erwin, Rung, Stefan, Hellmann, Ralf, 2012. Diffractive beam shaping optics for efficient micromachining. In: Proceedings of the LASYS (Internationale Fachmesse für Laser-Materialbearbeitung) – SLT (Stuttgarter Lasertage) 2012.
  • Koller, Georg, Hessler, Steffen, Rosenberger, Manuel, Belle, Stefan, Hellmann, Ralf, 2012. Micro-structured optical waveguide fabrication in PMMA using low frequency reactive ion etching. In: Proceedings of the XXVI International MicroCAD Conference – Sensing Technologies, Miskolc (Hungary).
  • Girschikofsky, Maiko, Rosenberger, Manuel, Belle, Stefan, Brutschy, Malte, Waldvogel, Siegfried, Hellmann, Ralf, 2012. α-Cyclodextrin functionalized planar Bragg grating sensor for the detection of small arene traces in solvamt vapour. In: 14th international meeting on chemical sensors (IMCS 2012). S. 646 – 648. ISBN 978-3-9813484-2-2.
  • Rung, Stefan, Hellmann, Ralf, 2012. Laser scribing of metallized transparent conductive oxide – A comparative study using top hat and Gaussian beam profiles. In: Proceedings of the XXVI International MicroCAD Conference – Material Processing Technologies.
  • Girschikofsky, Maiko, Rosenberger, Manuel, Belle, Stefan, Hellmann, Ralf, 2012. Surface modifications of planar bragg grating refractive index sensors for gas detection. In: Proceedings of the XXVI International MicroCAD Conference – Sensing Technologies, Miskolc (Hungary).
  • Bischoff, Christian, Rung, Stefan, Hellmann, Ralf, 2012. Efficient micromachining of thin film layers with nanosecond lasers – beam shaping optics improve process quality and enhance throughput. In: Laser Technik Journal. 9(5), S. 15 – 20.
  • Heilmann, Eva-Maria, Hellmann, Ralf, 2011. High Speed Fibre Laser Material processing of Stainless Steel Tapes Under Tension. In: XXV International MicroCAD Conference - Material Processing Technologies, Miskolc (Hungary), 21-25.
  • Kalmár, László, Hellmann, Ralf, Régert, Tamás, Varga, Zoltan, 2011. Numerical simulation of heat transfer procedure in high power LED modules. In: Proceedings of the 12th technical and scientific meeting. S. 18 – 20.
  • Girschikofsky, Maiko, Rosenberger, Manuel, Belle, Stefan, Brutschy, Malte, Waldvogel, Siegfried, Hellmann, Ralf, 2011. Optical planar bragg grating sensor for real-time detection of benzene, toluene und xylene in solvent vapour. In: Sensors & Actuators, B - Chemical. 171/172(8/9), S. 338 – 342.
  • Girschikofsky, Maiko, Rosenberger, Manuel, Belle, Stefan, Brutschy, Malte, Waldvogel, Siegfried, Hellmann, Ralf, 2011. Highly sensitive detection of naphthalene in solvent vapor using a functionalized PBG refractive index sensor. In: Sensors. 12(2), S. 2018 – 2025.
  • Rosenberger, Manuel, Belle, Stefan, Hellmann, Ralf, 2011. Detection of biochemical reaction and DNA hybridization using a planar bragg grating sensor. In: Proceeding SPIE, Vol. 8073, article id: 80730C.
  • Risch, Anna, Christiansen, Anne, Hellmann, Ralf, Gockel, Tilo, 2011. Laserstrukturierung vonTCOs zur Herstellung organischer Leuchtdioden. In: Elektor, Sonderheft LEDs 3. 9, S. 39 – 41.
  • Amrhein, Frank, Kehrer, Martin, Schreck, Timo, Bochtler, Ulrich, Hellmann, Ralf, Kaloudis, Michael, 2011. More efficient curing of UV sensitive mounting materials. In: Practical metallography. 48(7), S. 356 – 364.
  • Gockel, Tilo, Engel, Michael, Hellmann, Ralf, 2011. 3D Laserscanning mit Linienlaser und Smart Camera – Systemauslegung mit Rasterlinsenoptik und Scheimpflugentzerrung. In: Elektor Sonderheft LEDs 3. 9, S. 79 – 84.
  • Schneider, Johannes, Bochtler, Ulrich, Hellmann, Ralf, Kaloudis, Michael, Gockel, Tilo, 2011. Effiziente Entwärmung eines Hochleistungs-UV-LED-Moduls. In: Elektor, Sonderheft LEDs 3. 2011(9), S. 12 – 17.
  • Heilmann, Eva-Maria, Hellmann, Ralf, 2011. Water jet guided laser cutting using a green disc laser. In: Proceeding XXV microCAD, International scientific conference, 2011, Section K: Material science/Material processing technologies.
  • Rosenberger, Markus, Belle, Stefan, Hellmann, Ralf, 2011. Detection of unlabeled DNA hybridization with a planar Bragg Grating Sensor. In: XXV International MicroCAD Conference – Sensing Technologies, Miskolc (Hungary). S. 67 – 72.
  • Amrhein, Frank, Kehrer, Martin, Schreck, Timo, Bochtler, Ulrich, Hellmann, Ralf, Kaloudis, Michael, 2011. UV-LED-Bestrahlung von Vergussmaterial: Schnelle Aushärtung auch im Schatten. In: adhäsion KLEBEN & DICHTEN. 5, S. 38 – 41.
  • Risch, Anna, Hellmann, Ralf, 2011. Laser Scribing of Gallium Doped Zinc Oxide Thin Films using Picosecond Laser. In: Applied Surface Science. 258(5), S. 1849 – 1853.
  • Hellmann, Ralf, Moorhouse, Colin, 2011. Laser patterning of transparent electrode films, from solar panels through high-end display. In: Industrial Laser Solutions Magazine. 11,
  • Heilmann, Eva-Maria, Hellmann, Ralf, Seidl, Albrecht, 2011. Water Jet Guided Laser Cutting of Silicon Thin Films Using 515nm Disc Laser. In: Journal of Laser Micro- and Nanoengineering. 6(2), S. 168.
  • Adelmann, Benedikt, Hellmann, Ralf, 2011. Fast Laser Cutting Optimization Algorithm. In: Physics Procedia 12-1, Elsevier Properties S.A. 12(Part A), S. 591 – 598.
  • Risch, Anna, Hellmann, Ralf, 2011. Picosecond Laser Patterning of ITO Thin Films. In: Physics Procedia 12-1, Elsevier Properties S.A. 12, S. 133 – 140.
  • Adelmann, Benedikt, Hellmann, Ralf, 2011. Different modulation schemes in fibre laser cutting. In: Proceeding XXV microCAD, International scientific conference, 2011, Section K: Material science/Material processing technologies. S. 1 – 6.
  • Adelmann, Benedikt, Hellmann, Ralf, 2011. DOE based optimization of fibre laser cutting of metals. In: Proceeding XXV microCAD, International scientific conference, 2011, Section K: Material science/Material processing technologies. S. 7 – 12.
  • Risch, Anna, Hellmann, Ralf, 2011. Laser induced modification of GZO thin film. In: Proceeding XXV microCAD, International scientific conference, 2011, Section K: Material science/Material processing technologies. S. 69 – 74.
  • Risch, Anna, Hellmann, Ralf, 2011. ITO thin film laser patterning by picosecond laser. In: Proceeding XXV microCAD, International scientific conference, 2011, Section K: Material science/Material processing technologies. S. 63 – 68.
  • Rosenberger, Manuel, Belle, Stefan, Hellmann, Ralf, 2011. Detection of unlabeled DNA hybridization with a planar bragg grating sensor. In: Proceeding XXV microCAD, International scientific conference, 2011, Section R. S. 67 – 72.
  • Rosenberger, Manuel, Belle, Stefan, Hellmann, Ralf, 2011. Optical interrogation of chemical and temperature bragg grating sensors using tunable fiber coupled bandpass filter. In: Proceeding XXV microCAD, International scientific conference, 2011, Section H. S. 25 – 30.
  • Belle, Stefan, Rosenberger, Manuel, Hellmann, Ralf, 2011. Optical fibre sensing in the production process and storage of biofuels. In: Proceeding XXV microCAD, International scientific conference, 2011, Section A. S. 21 – 26.
  • Belle, Stefan, Rosenberger, Manuel, Hellmann, Ralf, 2011. Evanescent wave planar bragg grating sensor for real-time detection of unlabelled biomolecules. In: Optics Express.
  • Kaloumenos, Mareiki, Amrhein, Frank, Glaab, Johannes, Sauer, Michael, Hellmann, Ralf, Kaloudis, Michael, 2010. Development of a UV-Light Source with Highest Power Density Based on Light Emitting Diode Technology for Applications in Production Engineering, in Production Engineering and manufacturing Systems. In: Proceedings of the XXIV International Scientific Conference Miskolc, Ungarn.
  • Hellmann, Ralf, Glaab, Johannes, Gockel, Tilo, 2010. Wasserentkeimung mit UV-Leuchtdioden. In: Elektor Sonderheft, LEDs 2. 2010(2), S. 40 – 45.
  • Bochtler, Ulrich, Hellmann, Ralf, Kaloudis, Michael, Amrhein, Frank, Glaab, Johannes, Kaloumenos, Mareiki, Sauer, Michael, Gockel, Tilo, 2010. LUVLED - UV-Leistungslichtquelle auf Leuchtdiodenbasis. In: Elektor Sonderheft, LEDs 2. 2011(2), S. 57 – 63.
  • Amrhein, Frank, Bochtler, Ulrich, Hellmann, Ralf, Kaloudis, Michael, Kaloumenos, Mareiki, 2010. Vergleich der thermischen Eigenschaften unterschiedlicher insulated metal substrat-Leiterplatten. In: PLUS, Leiterplattentechnik. 8, S. 1758.
  • Belle, Stefan, Scheurich, Steffen, Hellmann, Ralf, So, Sik, Sparrow, Ian, Emmerson, Greg, 2010. Refractive index sensing for online monitoring water and ethanol contents in biofuels. In: Sensors. 7726, ISSN 1424-8220.
  • Glaab, Johannes, Hellmann, Ralf, 2010. Small-scale low-through UV-C LED disinfection device, in waste processing and recycling. In: Proceedings of the XXIV international Scientific conference Miskolc, Ungarn.
  • Hühnlein, Kristof, Tschirpke, Katrin, Hellmann, Ralf, 2010. Optimisation of laser cutting using design of experiment - A comparative study of cutting thin ceramic layers using a fibre laser and a CO2 laser. In: Physics procedia. 6th international conference on laser assisted net shape engineering. S. 243 – 252. ISSN 1875-3892.
  • Risch, Anna, Hühnlein, Kristof, Knöll, Jürgen, Hellmann, Ralf, 2010. Picosecond and nanosecond pulsed laserscribing on transparent conductive indium tin oxide. In: Journal of Material processing technolgies. Proceedings of the XXIV international scientific conference Miskolc, Ungarn. ISSN 0924-0136.
  • Bochtler, Ulrich, Hellmann, Ralf, Kaloudis, Michael, 2010. Neuartige UV-Lichtquelle auf Leuchtdiodenbasis, Packaging und Hybridschaltungen. In: PLUS. 2,
  • Glaab, Johannes, Hellmann, Ralf, 2010. Germicidal potential of ultraviolet-LED emitting different wavelength for the inactivation of indigenous coliform bacteria. In: Water research conference, Lissabon, Portugal.
  • Risch, Anna, Hühnlein, Kristof, Knöll, Jürgen, Hellmann, Ralf, 2009. Laserscribing of transparent conductive oxides - a comparative study using nanosecond and picosecond pulsed solid state lasers. In: Proceedings of the 20st International Scientific Conference, Mittweida, 2009.
  • Rosenberger, Manuel, Belle, Stefan, Hellmann, Ralf, 2009. Optical interrogation of bragg grating sensors using tunable fibre based bandpass filter. In: Proceedings of the 20st international science conference, Mittweida.
  • Belle, Stefan, Scheurich, Steffen, Hellmann, Ralf, 2009. Interrogation water content in organic solvents by planar bragg grating sensors. In: Proceedings SENSOR. S. 324 – 329. ISBN 978-3-9810993-6-2.
  • Scheurich, Steffen, Belle, Stefan, Hellmann, Ralf, So, Sik, Sparrow, Ian, Emmerson, Greg, 2009. Application of a silica-on-silicon planar optical waveguide. Bragg grating sensor for organic liquid compound detection. In: SPIE Optics an optoelectronics conference, Proceedings of SPIE, Vol. 7356, Prag, CR. ISBN 978-0819476302.
  • Scheurich, Steffen, Belle, Stefan, Hellmann, Ralf, So, Sik, Sparrow, Ian, Emmerson, Greg, 2009. Planar optical waveguide bragg grating chemical sensor for online process control. In: 3rd integrated optics - sensors, sensing structures and methodes Korbielow, PL.

Bemerkungen

Leiter Labor für Lasertechnik
Leiter Labor für Technische Optik
Auslandsbeauftragter des FB Ingenieurwissenschaften
Beauftragter für Technologie- und Wissenstransfer des FB Ingenieurwissenschaften