Journal Papers

@inproceedings{jimenez2024using,

title = {Using complex master-slave protocol for OCT with bidirectional sweeping laser},

author = {Alejandro Martínez Jiménez and Esteban Andres Proano Grijalva and Adrian Bradu and Bjorn Meyer and Thor Ansbaek and Kresten Yvind and Adrian Podoleanu},

doi = {10.1117/12.3005674},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXVIII},

pages = {PC128301I},

organization = {SPIE},

abstract = {This work presents a novel approach to the use of bidirectional swept sources. A MEMS-VCSEL light source with a bidirectional sweeping rate of 1.6MHz is used. Bidirectional sweeping poses a challenge as the tuning curve is different for each sweep. To exploit the full performance of the swept source, both sweeps within the bidirectional sweeping must be utilized and compensated. The proposed approach involves a software solution based on the Master-Slave protocol, where sets of theoretically inferred channelled spectra (masks) are prepared in advance for each sweep. The phase retrieval method called CMS (Complex Master Slave) is employed to handle bidirectional sweeping SS-OCT, involving the calculation of two sets of functions for each sweeping direction. The correct set of masks is used for each sweep direction to accurately represent A-Scan peaks. Differences in the sweep are analysed. Finally, the proposed method is successfully tested on posterior and anterior chambers.},

keywords = {laser, Master-Slave, swept source},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{nteroli2024master,

title = {Master-slave enhanced optical coherence microscopy for real-time optical biopsy imaging},

author = {Gianni Nteroli and Adrian Podoleanu and Adrian Bradu},

doi = {10.1117/12.3016320},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

booktitle = {Clinical Biophotonics III},

volume = {13009},

pages = {62–68},

organization = {SPIE},

abstract = {Diagnosing skin cancer, such as basal cell carcinoma, requires a biopsy, which is a time-consuming and expensive process. Therefore, it is essential to explore alternative diagnostic methods that are both more efficient and effective. We developed a handheld optical coherence microscopy (OCM) imaging device to achieve high-resolution optical biopsies in real-time. The instrument uses a variable focus liquid lens that allows fast shifting of the focus inside the sample, resulting in high-resolution lateral images throughout an extended axial imaging range. Our instrument can produce images with an axial resolution of approximately 5 μm, currently limited by the light source employed, and better than 2 μm transversal resolution images. The acquisition, data processing, and display of the 3D volumes are performed in real time, primarily enabled by the Master-Slave approach employed to produce the optical biopsies. The acquisition rate of the current camera used in the spectrometer is limited to 70 kHz. Our benchmarking shows that the real-time operation of the instrument can be sustained even at over 250 kHz solely by utilizing the computing power of the CPU, with no need to employ graphic cards or FPGAs. The instrument’s capability is showcased through images featuring various samples, such as an IR card and skin.},

keywords = {Gabor Fusion, Master-Slave, Microscopy},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{nteroli2024development,

title = {Development of a combined multi-spectral optoacoustic microscopy and optical coherence tomography imaging instrument for mapping multiple chromophores in biological tissues},

author = {Gianni Nteroli and Manoj K Dasa and Giulia Messa and Stella Koutsikou and Magalie Bondu and Peter M Moselund and Christos Markos and Ole Bang and Adrian Podoleanu and Adrian Bradu},

doi = {10.1117/12.3017439},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

booktitle = {Biomedical Spectroscopy, Microscopy, and Imaging III},

volume = {13006},

pages = {104–109},

organization = {SPIE},

keywords = {Microscopy, Optoacoustic},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{duma2024oct,

title = {OCT-based beneath-the-surface investigations in ceramics sintering: modeling for the most relevant characteristic parameter},

author = {Virgil-Florin Duma and Cosmin G Sinescu and Adrian Bradu and Adrian GH Podoleanu},

doi = {10.1117/12.3027313},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

booktitle = {Biomedical Spectroscopy, Microscopy, and Imaging III},

pages = {PC130060Y},

organization = {SPIE},

abstract = {

We present a investigations of dental ceramics using in-house developed swept source (SS) optical coherence tomography (OCT) systems. The issue is related to the loss of calibration of ovens utilized for the fabrication of dental crowns. In the first study [http://dx.doi.org/10.3390/app7060552], metal-ceramics crowns were manufactured, in five study groups, with five maximum sintering temperatures: a normal one, two lower levels and two upper levels (up to +50ºC with regard to normal). OCT B- and C-scans were obtained, and qualitative rules-of-thumb were extracted to assess the oven temperature level by observing ceramic grains bellow the level of the tooth-shaped crowns. The second study [https://doi.org/10.3390/ma12060947] moved to a quantitative assessment of the calibration loss of the ovens. A second type of material (for all-ceramic crowns) was considered, and three levels of its specific temperature were tested. For both ceramics reflectivity curves were obtained from OCT C-scans. These analyses demonstrated that there is (only) one parameter consistent with the shift of the maximum temperature in the oven: the ratio of the maximum and minimum (filtered) reflectivity.},

keywords = {Ceramics, OCT},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{jimenez2023dual,

title = {Dual Ultrahigh Speed Swept-Source & Time Domain Optical Coherence Tomography system using a time stretch laser and a KTN deflector},

author = {Alejandro Martínez Jiménez and Sacha Grelet and Patrick Bowen Montague and Adrian Bradu and Adrian Podoleanu},

year  = {2023},

date = {2023-01-01},

booktitle = {European Conference on Biomedical Optics},

pages = {126320B},

organization = {Optica Publishing Group},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{nteroli2023enhancing,

title = {Enhancing the axial resolution of an optoacoustic microscopy imaging instrument by using a pico-second pulse duration laser},

author = {Gianni Nteroli and Giulia Messa and Stella Koutsikou and Manoj K Dasa and Antti Penttinen and Antti Härkönen and Mircea Guina and Adrian Podoleanu and Adrian Bradu},

doi = {10.1117/12.2670901},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

booktitle = {European Conference on Biomedical Optics},

pages = {1263106},

organization = {Optica Publishing Group},

abstract = {In conventional optoacoustic microscopy, nanosecond pulse duration lasers are employed. When a laser delivering shorter pulse durations is used, it is expected that, from a theoretical point of view, broader, higher-frequency acoustic waves to be generated, therefore a better axial resolution of the instrument. In the present report, this advantage, offered by a picosecond duration pulse laser, to experimentally demonstrate that the axial resolution of an optoacoustic microscopy instrument can be enhanced was exploited. In comparison to a 2 ns pulse duration, an improvement in the axial resolution of ~50% is demonstrated by using excitations with pulses of duration <100 ps. Details of an optoacoustic microscopy instrument, operating at 532 nm, capable to provide high-resolution axial and lateral optoacoustic images, are also presented. The capabilities of the instrument are demonstrated by in-vivo images of Xenopus laevis brain with a similar ~3.8 µm lateral resolution throughout the whole axial imaging range.},

keywords = {laser, Microscopy, Optoacoustic},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{nteroli2023novel,

title = {Novel calibration method for optical coherence tomography instruments using multiple spectrometers},

author = {Gianni Nteroli and Lucy Abbott and Rasmus D Engelsholm and Patrick Bowen Montague and Adrian Podoleanu and Adrian Bradu},

doi = {10.1117/12.2670909},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

booktitle = {European Conference on Biomedical Optics},

pages = {126320E},

organization = {Optica Publishing Group},

abstract = {In this report, a novel calibration method is introduced, which can be used in camera-based optical coherence tomography (OCT) instruments employing several spectrometers. To ensure that all spectrometers are calibrated, i.e. they sense the same spectral range and the distribution of the optical frequencies across the pixels of the cameras is the same, a hybrid method was used involving (i) a hardware procedure for an initial estimation of the edges of the spectra and (ii) a numerical Monte-Carlo based technique. The utility of such a procedure is demonstrated in an OCT system using a balance-detection (BD) scheme. The OCT system employs a single transmission diffraction grating and is driven by a supercontinuum source operating in the visible spectral range. Spectral alignment is paramount in producing high-sensitivity images free of artefacts. To ensure correct calibration, and speed up the calibration procedure, the master-slave (MS) technique of generating axial reflectivity profiles is employed. Preliminary results show an improvement of the signal of ~ 3dB and a mitigation of the background noise of over 5 dB.},

keywords = {balance detection, caibration, Master-Slave},

pubstate = {published},

tppubtype = {inproceedings}

}