Philipp Lamminger

Doktorand / PhD Student


Universität zu Lübeck
Institut für Biomedizinische Optik

Maria-Goeppert-Str. 1
23562 Lübeck
Gebäude MFC 1, Raum 2.19

Email:
Phone:
+49 451 3101 3229
Fax:
+49 451 3101 3233



Publications

2019

  • Weng, Daniel and Hakert, Hubertus and Bloemker, Torben and Kolb, Jan Philip and Strauch, Matthias and Eibl, Matthias and Lamminger, Philipp and Karpf, Sebastian and Huber, Robert: Sub-Nanosecond Pulsed Fiber Laser for 532nm Two-Photon Excitation Fluorescence (TPEF) Microscopy of UV Transitions. in 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), IEEE, 2019
    BibTeX Link
    @InProceedings{Weng2019,
      author    = {Weng, Daniel and Hakert, Hubertus and Bloemker, Torben and Kolb, Jan Philip and Strauch, Matthias and Eibl, Matthias and Lamminger, Philipp and Karpf, Sebastian and Huber, Robert},
      booktitle = {2019 Conference on Lasers and Electro-Optics Europe {\&} European Quantum Electronics Conference ({CLEO}/Europe-{EQEC})},
      title     = {Sub-Nanosecond Pulsed Fiber Laser for 532nm Two-Photon Excitation Fluorescence ({TPEF}) Microscopy of {UV} Transitions},
      year      = {2019},
      publisher = {{IEEE}},
      abstract  = {Summary form only given. Two-photon microscopy is a powerful technique for in vivo imaging, due to its high penetration depth and axial sectioning. Usually excitation wavelengths in the near infrared are used. However, most fluorescence techniques for live cell imaging require labeling with exogenous fluorophores. It has been shown that shorter wavelengths can be used to excite the autofluorescence of endogenous proteins, e.g. tryptophan. Recently we demonstrated a fully fiber-based laser source built around a directly modulated, ytterbium amplified 1064 nm laser diode with sub-nanosecond pulses for two-photon imaging [2]. The overall system enables to capture high-speed fluorescence lifetime imaging (FLIM) with single pulse excitation. Here, we extend the spectral range of this laser source by frequency doubling it to 532nm to achieve two-photon excited fluorescence microscopy (TPM) in the ultraviolett (UV) range to harness endogenous autofluorescence. In this presentation we explore first TPM results of tryptophan to investigate signal levels and fi delity before transitioning to biological tissues. It has been shown that TPM of endogenous tryptophan can be used to visualize immune system activity in vivo. Our laser source could be a cheap, flexible and fiber-based alternative to the OPO-based Ti:Sa Lasers currently employed. The basic concept of our design is to shift the wavelength of the pulsed fiber-based master oscillator power amplifier (MOPA) by second-harmonic generation (SHG) using phase-matching in a KTP crystal. This generates a coherent output at 532nm at a maximal peak power of 500W. We achieved a maximum conversion efficiency of about 17%. After the SHG module, the 532nm light is coupled into a single-mode fiber and delivered to a home built microscope. A 40x microscope objective is used to excite the sample and epi-collect the fluorescence. The fluorescence is recorded on a UV-enhanced photomultiplier tube (PMT). For a proof of concept measurement, crystalized tryptophan was imaged. Here we show signals of pure tryptophan, with laser parameters of 1MHz repetition rate and 100ps pulse duration. We used spectral bandpass fi lters in order to detect only fluorescence signal, however, from crystalized tryptophan we observed an unexpected short lifetime. We have recently shown that we can shift our laser output from 1064nm to longer wavelengths. By shifting to 1180nm and frequency doubling to 590nm a more efficient fluorescence excitation of tryptophan can be achieved. In the future we aim at in vivo imaging with our setup.},
      doi       = {10.1109/CLEOE-EQEC.2019.8872571},
      keywords  = {AG-Huber_NL;amplifiers;biological tissues;biomedical optical imaging;cellular biophysics;fluorescence;laser applications in medicine;medical image processing;molecular biophysics;optical microscopy;proteins;two-photon processes;ultraviolet spectra;two-photon excitation fluorescence microscopy;UV transitions;excitation wavelengths;fluorescence techniques;live cell imaging;subnanosecond pulsed fiber laser;TPEF microscopy;exogenous fluorophores;autofluorescence;endogenous proteins;fiber-based laser source;laser diode;two-photon imaging;high-speed fluorescence lifetime imaging;FLIM;single pulse excitation;tryptophan;biological tissues;immune system activity;OPO-based Ti:Sa lasers;pulsed fiber-based master oscillator power amplifier;MOPA;second-harmonic generation;SHG;phase-matching;KTP crystal;UV-enhanced photomultiplier tube;laser parameters;spectral bandpass filters;fluorescence excitation;Fluorescence;Laser excitation;Fiber lasers;Microscopy;Laser transitions;In vivo},
    }