@article{Singh:24,
author = {Awanish Pratap Singh and Madita G\"{o}b and Martin Ahrens and Tim Eixmann and Berenice Schulte and Hinnerk Schulz-Hildebrandt and Gereon H\"{u}ttmann and Mark Ellrichmann and Robert Huber and Maik Rahlves},
journal = {Opt. Express},
keywords = {Biomedical imaging; Endoscopic imaging; Imaging systems; Optical coherence tomography; Real time imaging; Vertical cavity surface emitting lasers},
number = {4},
pages = {5809--5825},
publisher = {Optica Publishing Group},
title = {Virtual Hall sensor triggered multi-MHz endoscopic OCT imaging for stable real-time visualization},
volume = {32},
month = {Feb},
year = {2024},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-32-4-5809},
doi = {10.1364/OE.514636},
abstract = {Circumferential scanning in endoscopic imaging is crucial across various disciplines, and optical coherence tomography (OCT) is often the preferred choice due to its high-speed, high-resolution, and micron-scale imaging capabilities. Moreover, real-time and high-speed 3D endoscopy is a pivotal technology for medical screening and precise surgical guidance, among other applications. However, challenges such as image jitter and non-uniform rotational distortion (NURD) are persistent obstacles that hinder real-time visualization during high-speed OCT procedures. To address this issue, we developed an innovative, low-cost endoscope that employs a brushless DC motor for scanning, and a sensorless technique for triggering and synchronizing OCT imaging with the scanning motor. This sensorless approach uses the motor\&\#x2019;s electrical feedback (back electromotive force, BEMF) as a virtual Hall sensor to initiate OCT image acquisition and synchronize it with a Fourier Domain Mode-Locked (FDML)-based Megahertz OCT system. Notably, the implementation of BEMF-triggered OCT has led to a substantial reduction in image jitter and NURD (\<4 mrad), thereby opening up a new window for real-time visualization capabilities. This approach suggests potential benefits across various applications, aiming to provide a more accurate, deployable, and cost-effective solution. Subsequent studies can explore the adaptability of this system to specific clinical scenarios and its performance under practical endoscopic conditions.},
}

@ARTICLE{10122996,

  author={Latus, Sarah and Grube, Sarah and Eixmann, Tim and Neidhardt, Maximilian and Gerlach, Stefan and Mieling, Robin and Hüttmann, Gereon and Lutz, Matthias and Schlaefer, Alexander},

  journal={IEEE Transactions on Biomedical Engineering}, 

  title={A Miniature Dual-Fiber Probe for Quantitative Optical Coherence Elastography}, 

  year={2023},

  volume={},

  number={},

  pages={1-9},

  doi={10.1109/TBME.2023.3275539}}

@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{Jaeckle2021c,
author = {J{\"{a}}ckle, Sonja and Eixmann, Tim and Matysiak, Florian and Sieren, Malte Maria and Horn, Marco and Schulz-Hildebrandt, Hinnerk and H{\"{u}}ttmann, Gereon and P{\"{a}}tz, Torben},
doi = {doi:10.1515/cdbme-2021-1004},
journal = {Current Directions in Biomedical Engineering},
year = {2021},
number = {1},
pages = {17--20},
title = {{3D Stent Graft Guidance based on Tracking Systems for Endovascular Aneurysm Repair:}},
url = {https://doi.org/10.1515/cdbme-2021-1004},
volume = {7},
}

@article{Cereda-2021,
   author = {Cereda, M G;Parrulli, S;Douven, Y. G. M.;Faridpooya, K;van Romunde, S;Hüttmann, G;Eixmann, T;Schulz-Hildebrandt, H;Kronreif, G;Beelen, M and de Smet, M D.},
   title = {Clinical Evaluation of an Instrument-Integrated OCT-Based Distance Sensor for Robotic Vitreoretinal Surgery},
   journal = {Ophthalmology Science},
   volume = {1(4)},
  
   pages = {100085},
   ISSN = {2666-9145},
   DOI = {https://doi.org/10.1016/j.xops.2021.100085},
  
   year = {2021},
   type = {Journal Article}
}

@article{Jackle2021,
abstract = {Background: In endovascular aneuysm repair (EVAR) procedures, medical instruments are currently navigated with a two-dimensional imaging based guidance requiring X-rays and contrast agent. Methods: Novel approaches for obtaining the three-dimensional instrument positions are introduced. Firstly, a method based on fibre optical shape sensing, one electromagnetic sensor and a preoperative computed tomography (CT) scan is described. Secondly, an approach based on image processing using one 2D fluoroscopic image and a preoperative CT scan is introduced. Results: For the tracking based method, average errors from 1.81 to 3.13 mm and maximum errors from 3.21 to 5.46 mm were measured. For the image-based approach, average errors from 3.07 to 6.02 mm and maximum errors from 8.05 to 15.75 mm were measured. Conclusion: The tracking based method is promising for usage in EVAR procedures. For the image-based approach are applications in smaller vessels more suitable, since its errors increase with the vessel diameter.},
author = {J{\"{a}}ckle, Sonja and Lange, Annkristin and Garcia-Vazquez, Veronica and Eixmann, Tim and Matysiak, Florian and Sieren, Malte Maria and Horn, Marco and Schulz-Hildebrandt, Hinnerk and H{\"{u}}ttmann, Gereon and Ernst, Floris and Heldmann, Stefan and P{\"{a}}tz, Torben and Preusser, Tobias},
doi = {10.1002/rcs.2327},
file = {:Users/schulz-hildebrandt/Documents/Mendeley Desktop/J{\"{a}}ckle et al/International Journal of Medical Robotics and Computer Assisted Surgery/J{\"{a}}ckle et al. - 2021 - Instrument localisation for endovascular aneurysm repair Comparison of two methods based on tracking systems or.pdf:pdf},
issn = {1478596X},
journal = {International Journal of Medical Robotics and Computer Assisted Surgery},
keywords = {2D/3D registration,3D localisation,computer-assisted surgery,electromagnetic tracking system,endovascular procedures,fibre optical shape sensing},
number = {6},
pages = {e2327},
year = {2021},
title = {{Instrument localisation for endovascular aneurysm repair: Comparison of two methods based on tracking systems or using imaging}},
volume = {17}
}

@article{jackle2020,
title = {Three-dimensional guidance including shape sensing of a stentgraft system for endovascular aneurysm repair},
author = {Jäckle,S; Garcia-Vazquez,V; Eixmann, T; Matysiak, F; von Haxthausen,F; Sieren; M m; Schulz-Hildebrandt, H;  H\"{u}ttmann, G; Ernst, F; Kleemann, M and P\"{a}tz, T},
url = {https://doi.org/10.1007/s11548-020-02167-2},

isbn = {1861-6429},
year = {2020},
date = {2020-04-06},
journal = {Int J  Comp Assis Radiology and Surgery},
abstract = {During endovascular aneurysm repair (EVAR) procedures, medical instruments are guided with two-dimensional (2D) fluoroscopy and conventional digital subtraction angiography. However, this requires X-ray exposure and contrast agent is used, and the depth information is missing. To overcome these drawbacks, a three-dimensional (3D) guidance approach based on tracking systems is introduced and evaluated.},
keywords = {HSH},
pubstate = {published},
tppubtype = {article}
}

@proceedings{Horn2019b,
title = {First Steps into Catheter Guidance Including Shape Sensing for Endovascular Aneurysm Repair Procedures},
author = {Marco Horn and Sonja J\"{a}ckle and Felix von Haxthausen and Tim Eixmann and Hinnerk Schulz-Hildebrandt and Gereon H\"{u}ttmann and Juljan Bouchagiar and Florian Matysiak and Mark Kaschwich and Markus Kleemann and Floris Ernst and Ver\'{o}nica Garc\'{i}a-V\'{a}zquez and Torben P\"{a}tz},
doi = {10.1016/J.EJVS.2019.09.091},
issn = {1078-5884},
year  = {2019},
date = {2019-12-13},
journal = {European Journal of Vascular and Endovascular Surgery},
volume = {58},
number = {6},
pages = {e610--e611},
publisher = {W.B. Saunders},
keywords = {Sensing, Fiber},
pubstate = {published},
tppubtype = {proceedings}
}

@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.},
}