Dr. rer. nat. Martin Ahrens

@inproceedings{10.1117/12.2652955,
author = {Awanish Pratap Singh and Madita G{\"o}b and Martin Ahrens and Tim Eixmann and Hinnerk Schulz-Hildebrandt and Gereon H{\"u}ttmann and Robert Huber and Maik Rahlves},
title = {{Synchronous high-speed OCT imaging with sensor less brushless DC motor and FDML laser in a phase-locked loop}},
volume = {12367},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXVII},
editor = {Joseph A. Izatt and James G. Fujimoto},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {1236703},
abstract = {High-speed endoscopic optical coherence tomography (OCT) imaging in the MHz range has shown great potential in various medical applications ranging from cancer screening to vascular disease monitoring. High-speed imaging always suffers from non-uniform rotational distortion (NURD) due to asynchronous motor rotation with the OCT system. Several research groups have previously attempted to solve this problem, using either an expensive motor with a sensor or numerical correction after data acquisition. However, both techniques pose challenges for practical use. Therefore, in this study, we use an inexpensive sensorless brushless DC motor with a Fourier domain mode-locked (FDML) laser-based MHz OCT system and try to resolve the problem of synchronization using three different modalities, (i) Slave-mode: The FDML frequency serves as a master frequency for the motor, which is phase-locked to the FDML frequency, (ii) Master-mode: The revolution trigger obtained from the motor’s back electromotive force (BEMF) signal serves as a trigger signal for the OCT imaging system, (iii) Both: Fully synchronized setup, where the motor rotation is synchronized with the laser and the imaging system is synchronized with the motor to achieve phase-stable OCT imaging. The first case slightly fluctuates in live preview and imaging due to the absence of a revolution trigger, while the second has varying motor speeds. Therefore, we use the third case to phase-lock the motor with FDML and get a distortion-free live preview and image acquisition. Finally, we demonstrate high-speed SS-OCT structural imaging (at 3.3 MHz A-scan rates) of a finger with a 16 mm diameter probe (at 40,000 rpm).},
keywords = {Optical Coherence Tomography, Endoscopy, FDML , Closed Loop Motor Control, NURD compensation, Brushless DC Motor, Back Electromotive Force},
year = {2023},
doi = {10.1117/12.2652955},
URL = {https://doi.org/10.1117/12.2652955}
}

@article{Musial-2022,
   author = {Musial, G;Kohlfaerber, T;Ahrens, M;Schulz-Hildebrandt, H;Steven, P and Hüttmann, G},
   title = {Dynamic Contrast Microscopic Optical Coherence Tomography As a Novel Method for Assessing Corneal Epithelium During Exposure to Benzalkonium Chloride},
   journal = {Translational Vision Science & Technology},
keywords = {toxicity; optical coherence tomography; benzalkonium chloride},
   volume = {11(5)},

   pages = {28-28},
   ISSN = {2164-2591},
   DOI = {10.1167/tvst.11.5.28},
   url = {https://doi.org/10.1167/tvst.11.5.28},
   year = {2022},
   type = {Journal Article}
}

@article{Kohlfarber2022,
   author = {Kohlfaerber, T;Pieper, M;Münter, M;Holzhausen, C;Ahrens, M;Idel, C;Bruchhage, K-L;Leichtle, A;König, P;Hüttmann, G and Schulz-Hildebrandt, H},
   title = {Dynamic microscopic optical coherence tomography to visualize the morphological and functional micro-anatomy of the airways},
   journal = {Biomedical Optics Express},
   volume = {13 (6)},
   pages = {3211-3223},
   DOI = {10.1364/BOE.456104},
  
   year = {2022},
   type = {Journal Article}
}

@article{Münter2021,
   author = {M. Münter, M. Pieper, T. Kohlfaerber, E. Bodenstorfer, M. Ahrens, C. Winter, R. Huber, P. König, G. Hüttmann and H. Schulz-Hildebrandt},
   title = {Microscopic optical coherence tomography (mOCT) at 600 kHz for 4D volumetric imaging and dynamic contrast},
   journal = {BiomedOptE},
   volume = {12(10)},
   Keywords = {CMOS cameras,Full field optical coherence tomography,High numerical aperture optics, Image processing,In vivo imaging,Medical imaging,Ag-Huber},
   pages = {6024-6039},
   DOI = {10.1364/BOE.425001},
  
   year = {2021},
   type = {Journal Article}
}

@inproceedings{10.1117/12.2575733,

title = {Endo-microscopic optical coherence tomography (emOCT) with dynamic contrast},

author = {Hinnerk Schulz-Hildebrandt and Martin Ahrens and Michael M\"{u}nter and Elisa Wilken and Tabea Kohlf\"{a}rber and Cornelia Holzhausen and Peter K\"{o}nig and Gereon H\"{u}ttmann},

editor = {Guillermo Tearney J M.D. and Thomas D Wang and Melissa J Suter},

url = {https://doi.org/10.1117/12.2575733},

doi = {10.1117/12.2575733},

year  = {2021},

date = {2021-01-01},

booktitle = {Endoscopic Microscopy XVI},

volume = {11620},

publisher = {SPIE},

organization = {International Society for Optics and Photonics},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{10.1117/12.2578787,

title = {Voice coil based endomicroscopic optical coherence tomography probe for in vivo mucosa examination},

author = {Martin Ahrens and Christian Idel and Peter K\"{o}nig and Gereon H\"{u}ttmann and Hinnerk Schulz-Hildebrandt},

editor = {Guillermo Tearney J M.D. and Thomas D Wang and Melissa J Suter},

url = {https://doi.org/10.1117/12.2578787},

doi = {10.1117/12.2578787},

year  = {2021},

date = {2021-01-01},

booktitle = {Endoscopic Microscopy XVI},

volume = {11620},

publisher = {SPIE},

organization = {International Society for Optics and Photonics},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@article{schneider2020,
   author = {Schneider, H.;Ahrens, M.;Strumpski, M.;Ruger, C.;Hafer, M.;Huettmann, G.;Theisen-Kunde, D.;Schulz-Hildebrandt, H. and Haak, R.},
   title = {An Intraoral OCT Probe to Enhanced Detection of Approximal Carious Lesions and Assessment of Restorations},
   journal = {J Clin Med},
   volume = {9(10)},
   keywords = {OCT; intraoral probe; carious lesions; caries diagnosis; dental restorations},
   ISSN = {2077-0383 (Print)
2077-0383 (Linking)},
   DOI = {10.3390/jcm9103257},
   
   year = {2020},
   type = {Journal Article}
}

@article{Münter2020,
   author = {Münter, M;Endt, M v;Pieper, M;Casper, M;Ahrens, M;Kohlfaerber, T;Rahmanzadeh, R;König, P;Hüttmann, G and Schulz-Hildebrandt, H},
   title = {Dynamic contrast in scanning microscopic OCT},
   journal = {Optic Letters},
url = {https://arxiv.org/abs/2003.00006},
   year = {2020},
   type = {Journal Article}
}

@inproceedings{Haak2019,
author = {Haak, Rainer and Ahrens, Martin and Schneider, Hartmut and Strumpski, Michaela and Rueger, Claudia and Haefer, Matthias and H{\"{u}}ttmann, Gereon and Theisen-Kunde, Dirk and Schulz-Hildebrandt, Hinnerk},
booktitle = {Proc. SPIE 11073, Clinical and Preclinical Optical Diagnostics II},
doi = {10.1117/12.2527185},
isbn = {9781510628397},
number = {110730W},
pages = {1--4},
title = {{Handheld OCT probe for intraoral diagnosis on teeth}},
keywords = {OCT,Endoskope},
year = {2019},
}

@article{Schulz-Hildebrandt:18,
author = {Hinnerk Schulz-Hildebrandt and Tom Pfeiffer and Tim Eixmann and Sabrina Lohmann and Martin Ahrens and Joshua Rehra and Wolfgang Draxinger and Peter K\"{o}nig and Robert Huber and Gereon H\"{u}ttmann},
journal = {Opt. Lett.},
keywords = {Fiber optics imaging; Endoscopic imaging; Medical and biological imaging; Optical coherence tomography; Fourier domain mode locking; Image quality; Optical coherence tomography; Single mode fibers; Step index fibers; Three dimensional imaging},
number = {18},
pages = {4386--4389},
publisher = {Optica Publishing Group},
title = {High-speed fiber scanning endoscope for volumetric multi-megahertz optical coherence tomography},
volume = {43},
month = {Sep},
year = {2018},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-43-18-4386},
doi = {10.1364/OL.43.004386},
abstract = {We present a forward-viewing fiber scanning endoscope (FSE) for high-speed volumetric optical coherence tomography (OCT). The reduction in size of the probe was achieved by substituting the focusing optics by an all-fiber-based imaging system which consists of a combination of scanning single-mode fibers, a glass spacer, made from a step-index multi-mode fiber, and a gradient-index fiber. A lateral resolution of 11 $\mu$m was achieved at a working distance of 1.2 mm. The newly designed piezo-based FSE has an outer diameter of 1.6 mm and a rigid length of 13.5 mm. By moving the whole imaging optic in spirals for scanning the sample, the beam quality remains constant over the entire field of view with a diameter of 0.8 mm. The scanning frequency was adjusted to 1.22 kHz for use with a 3.28 MHz Fourier domain mode locked OCT system. Densely sampled volumes have been imaged at a rate of 6 volumes per second.},
}