Article
Dermatology
Terese Von Knorring, Niels Moller Israelsen, Vilde Ung, Julie L. Formann, Mikkel Jensen, Merete Haedersdal, Ole Bang, Gabriella Fredman, Mette Mogensen
Summary: This pilot study evaluated the ability of optical coherence tomography, reflectance confocal microscopy, photoacoustic imaging and high-frequency ultrasound to differentiate malignant from benign pigmented skin lesions. The results showed that the combination of optical coherence tomography, reflectance confocal microscopy and photoacoustic imaging enables image-guided bedside evaluation of suspicious pigmented skin tumors and may enable more efficient diagnosis of skin cancer.
ACTA DERMATO-VENEREOLOGICA
(2022)
Article
Optics
Callum R. Smith, Rasmus Dybbro Engelsholm, Ole Bang
Summary: Relative intensity noise (RIN) is an important parameter for evaluating the energy variations of ultrafast lasers. However, comparing RIN values is challenging due to various measurement and analysis techniques. In this study, we provide a clear definition of RIN as a percentage value for ultrafast laser systems. We also analytically describe the measurement of RIN in the time and frequency domains and reveal their equivalence under certain conditions. Experimental results demonstrate strong agreement between the expected and measured RIN values when appropriate measurements and signal processing are employed.
Article
Chemistry, Analytical
Rasmus Eilkaer Hansen, Thorsten Baek, Simon Lehnskov Lange, Niels Moller Israelsen, Markku Mantyla, Ole Bang, Christian Rosenberg Petersen
Summary: This article investigates two optical sensing techniques for non-destructive, non-contact characterization of paper thickness, surface roughness, and production defects. The demonstrations highlight the added functionality and potential of tomographic optical sensing methods towards industrial non-contact quality monitoring.
Article
Biochemical Research Methods
Manuel J. Marques, Michael R. Hughes, Adrian F. Uceda, Grigory Gelikonov, Adrian Bradu, Adrian Podoleanu
Summary: This paper introduces a method of converting a 1D scanning probe into a 2D scanning probe by manual scanning, allowing for real-time imaging and motion correction in forward-viewing optical coherence tomography (OCT) and fluorescence imaging. The approach is capable of handling out-of-plane motion at relatively high speeds.
BIOMEDICAL OPTICS EXPRESS
(2022)
Article
Optics
Rene Riha, Adrian Bradu, Adrian Podoleanu
Summary: This paper demonstrates a fast dual resonance akinetic optical swept source operating at 1550 nm. By employing a fiber intensity modulator as a mode-locking element and using a chirped fiber Bragg grating to provide sufficient dispersion, a tuning range of 25 nm was achieved for a sweep frequency of approximately 900 kHz.
Article
Optics
Hang Qu, Zhen Chen, Shixin Gao, Rui Min, Getinet Woyessa, Ole Bang, Heng Wang, Christophe Caucheteur, Xuehao Hu
Summary: In this Letter, we demonstrate the inscription of an 8 degrees-tilted fiber Bragg grating (TFBG) using a 520 nm femtosecond laser and the line-by-line (LbL) writing technique in single-mode step-index TOPAS/ZEONEX polymer optical fibers (POFs). The TFBG exhibits a large spectral range of cladding mode resonances covering 147 nm due to the tilt angle and the fiber refractive index. The refractive index sensitivity of the cutoff cladding mode is measured to be 507 nm/RIU (refractive index unit), with at least 6 nm/RIU sensitivity for single-resonance tracking near the cutoff mode.
Article
Chemistry, Analytical
Luis Pereira, Rui Min, Getinet Woyessa, Ole Bang, Carlos Marques, Humberto Varum, Paulo Antunes
Summary: This paper proposes a simple and cost-effective fiber Bragg grating (FBG) interrogation solution using ultra-short FBGs as edge filters. The solution is not only cost-effective but also has similar thermal sensitivities as standard uniform FBGs in silica fiber, making it suitable for dynamic measurements without complex equipment or calculations. Moreover, the solution has the capability of multiplexing multiple USFBGs in the same optical fiber, showing great potential for creating new sensing configurations.
Article
Optics
Shixin Gao, Heng Wang, Yuhang Chen, Heming Wei, Getinet Woyessa, Ole Bang, Rui Min, Hang Qu, Christophe Caucheteur, Xuehao Hu
Summary: In this paper, the authors propose first- and fourth-order FBG-based axial strain sensors. The FBGs are inscribed in step-index POFs via the PbP direct-writing technique. The results show that the first-order FBG exhibits a strain sensitivity of 1.17 pm/με, while the fourth-order FBG has a strain sensitivity between 1.249 pm/με and 1.296 pm/με. The split peaks of the Hi-Bi fourth-order FBG show strain sensitivities of approximately 1.44 pm/με and 1.55 pm/με respectively, with a peak difference presenting a strain sensitivity of approximately 0.11 pm/με.
Article
Engineering, Electrical & Electronic
Luis Pereira, Carlos Marques, Rui Min, Getinet Woyessa, Ole Bang, Humberto Varum, Paulo Fernando da Costa Antunes
Summary: This study presents the first inscription of fiber Bragg gratings (FBGs) in ZEONEX-480R microstructured polymer optical fiber (POF) using the fourth harmonic (266 nm) of a Nd:YAG laser system. The gratings were produced in 270-mu m diameter POF samples connectorized with ferrule connectors (FCs) using the phase mask method. The results demonstrate good stability and performance of the gratings in this polymer fiber, indicating potential cost-effective solutions.
IEEE SENSORS JOURNAL
(2023)
Article
Optics
Rasmus Eilkoer Hansen, Callum Robertson Smith, Asbjorn Moltke, Christian Rosenberg Petersen, Sidharthan Raghuraman, Seongwoo Yoo, Ole Bang
Summary: Mid-infrared supercontinuum lasers are crucial in various applications, but their noise level often limits their performance. This paper presents a simple technique to reduce the noise of high noise soliton-based supercontinuum sources. By adding a short piece of normal dispersion fiber, the spectrally distributed solitons are forced to broaden and overlap, effectively averaging out the noise. Experimental and numerical results demonstrate the effectiveness of this noise reduction method using a ZBLAN fiber based mid-IR SC source and highly nonlinear arsenic-sulfide fiber. The method is also applicable to other soliton-based near-IR or mid-IR SC sources and is compared to spectral alignment noise reduction mechanisms.
LASER & PHOTONICS REVIEWS
(2023)
Article
Optics
Rasmus Eilkaer Hansen, Asbjorn Meldgaard Moltke, Ole Bang
Summary: We numerically investigate high-power supercontinuum sources based on modulational instability. These sources have a spectra that reach the infrared material absorption edge, resulting in a strong narrow blue peak followed by a significant dip in longer wavelengths. We show that by modulating the input peak power, the flatness of the blue part can be improved by more than a factor of 3, although this leads to slightly higher relative intensity noise.
Article
Energy & Fuels
Christian Rosenberg Petersen, Soren Faester, Jakob Ilsted Bech, Kristine Munk Jespersen, Niels Moller Israelsen, Ole Bang
Summary: Leading edge erosion of wind turbine blades is a critical issue in wind energy production, causing lower efficiency and increased maintenance costs. This study examines the use of mid-infrared Optical Coherence Tomography (OCT) for non-destructive inspection of coated glass-fiber composite samples to identify subsurface coating defects.
Article
Chemistry, Analytical
Vivek Semwal, Oliver Rishoj Jensen, Ole Bang, Jakob Janting
Summary: This paper presents numerical and experimental results on the effects of spherical gold nanoparticles (AuNPs) size on Localized Surface Plasmon Resonance (LSPR) refractive index (RI) sensitivity, Figure of Merit (FoM), and penetration depth (dp). The study also investigates the influence of AuNP dimer interparticle distance (ds) on these parameters. The results show that a diameter of 60 nm AuNPs provides the best FoM. Furthermore, the interparticle distance between d = 20 nm and 60 nm AuNPs significantly affects the RI sensitivity. The importance of penetration depth information for biosensing using aptamers is discussed in relation to aptamer size.
Article
Optics
Vivek Semwal, Jonas Hojgaard, Emil Moller, Ole Bang, Jakob Janting
Summary: This study presents a polymer optical fiber fluorophore/aptamer competitive assay-based cortisol sensing principle and develops a low-cost two-fiber perpendicular design. The sensing principle has been demonstrated, but with a slow response, indicating the need for further improvement.
