PubMed İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8650

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  • Article
    Beam Moments of Higher-Order Annular Gaussian Beams in Tissue Turbulence
    (Optica Publishing Group, 2025) Arpali, Serap Altay; Arpali, Caglar; Baykal, Yahya
    Beam moments of the laser beam at the receiver plane were analyzed using our previously developed formula for the average light intensity of a higher-order annular Gaussian (HOAG) beam in the presence of biological tissue turbulence. HOAG beam moments are examined for the entities of power-in-the-bucket (PIB) and kurtosis across various tissue types such as the upper dermis (human), liver parenchyma (mouse), intestinal epithelium (mouse), and deep dermis (mouse). Moreover, beam moments are explored considering factors like the strength coefficient of the refractive-index fluctuations and the propagation distance. The PIB values for all HOAG beam modes are found to decrease exponentially and steadily, behaving similar to Gaussian beams as tissue length increases. As turbulence intensity increases, higher-order HOAG beam modes transfer optical energy to the receiver more efficiently than the lower order modes. Kurtosis analysis shows that at intermediate distances, the beam energy is distributed toward the edges, while at longer distances, the energy concentration is lower at the edges than at the center. This trend is reflected in increasing kurtosis values across all HOAG modes and tissue types. Considering the changes in PIB and kurtosis, higher-order HOAG modes transfer energy more conservatively within the tissue. Furthermore, the tissue type with the best transfer of optical power was observed to be the deep dermis (mouse). (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.
  • Article
    Laser Ablation Device with a Closed-Loop Control System
    (Optica Publishing Group, 2025) Beldek, Ulas; Erdogan, Kubra; Arpali, Caglar; Baykal, Yahya
    A laser ablation device with real-time beam power control is designed and implemented. This platform regulates the intensity of the laser beam by continuously measuring its intensity distribution. The quality of the ablation process is optimized through a closed-loop control system that uses a rule-based decision-making approach. The controller generates a starting signal for both the laser power and the motors based on the estimated quality of the ablation. The effects of laser power and light intensity on the formation of microchannels in polymethylmethacrylate material were investigated using the laser beam. The quality of the ablation geometry was assessed through image processing and inspection under a scanning electron microscope. The generated microchannels were analyzed in terms of roughness and residual thermal stress. A comparison of the experimental results with theoretical calculations and simulations revealed that the closed-loop control of laser beam power is effective for material etching and for creating smoother channel profiles. (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 3
    Intensity Fluctuations of Higher-Order Laser Modes in Jet Engine Exhaust Turbulence
    (Optica Publishing Group, 2025) Baykal, Yahya Kemal
    Intensity fluctuations quantified by the scintillation index are evaluated in jet engine exhaust turbulence when higher-order laser modes are used in optical wireless communication links. The jet engine exhaust turbulence power spectrum, modified by low-pass and high-pass filters, is employed. Intensity fluctuations are evaluated against the link length, structure constant, wave number (inverse of wavelength) (i.e., against turbulence strength), source size, and jet engine exhaust turbulence parameters. It is found that higher-order laser modes are better at mitigating the scintillations. Jet engine exhaust turbulence parameters are found to affect scintillations substantially. (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 1
    Propagation of Higher-Order Annular Gaussian Beams in Biological Tissues
    (Optica Publishing Group, 2025) Arpali, Serap Altay; Baykal, Yahya Kemal
    The propagation characteristics of a higher-order annular Gaussian (HOAG) beam in biological tissue turbulence are investigated. Average intensity at the receiver plane is found when the HOAG source field is used as excitation. The effects of the HOAG beam on different tissue types of the upper dermis (human), liver parenchyma (mouse), intestinal epithelium (mouse), and deep dermis (mouse) are studied. Variations of the average intensity versus the source and medium parameters such as the strength coefficient of the refractive-index fluctuations, propagation distance, wavelength, and beam size are presented. The results show that all modes of the HOAG beam can successively transmit beam energy at different levels of turbulence for all tissue types. At the same turbulence strength, HOAG beams having larger mode numbers transmit higher intensity to receivers than the modes with smaller mode orders, which is valid for all the examined tissue types. As the strength of tissue turbulence increases, the HOAG beam slowly turns into a pure Gaussian beam. For the different tissue types, the highest beam intensity at the receiver was observed for the deep dermis (mouse) tissue type. Despite the change in wavelength, refractive-index fluctuations, and source beam size, the highest beam transmission through the tissue in a turbulent environment was also observed for this same tissue type. This research may be useful in understanding the fundamentals of lighttissue interaction of HOAG laser beams, which may improve noninvasive disease detection and therapy methods through tissue in biophotonic technologies. (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.
  • Article
    Citation - WoS: 1
    Arbitrary Beam Propagation in an Underwater Turbulent Medium
    (Optica Publishing Group, 2025) Turan, Mehmet Furkan; Arpali, Caglar; Baykal, Yahya
    The average intensity for an arbitrary optical beam is obtained and presented by introducing propagation in underwater turbulence for arbitrary shaped optical beams that can be expressed by the known and newly generated source profiles. The received intensity of the arbitrary optical beam is found, and the effect of underwater turbulence on the received intensity is analyzed. The arbitrary source field profile is generated by dividing the source plane into pixels and by assigning the required amplitude and phase to each pixel. The average received intensity distributions are presented in the presence of underwater turbulence for different types of beams, such as the known Gaussian beam, arbitrary beams of chess board shape, and a beam consisting of the initial letters of our & Ccedil;ankaya & Uuml;niversitesi, & Ccedil;.& Uuml;. Our results can be used in applications such as underwater optical imaging systems, reflection from rough surfaces underwater, underwater wireless optical communication links, and underwater optical cryptography. (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.
  • Article
    Adaptive Optics Applied To the Scintillation Index in Tissues
    (Optica Publishing Group, 2025) Baykal, Yahya
    Mitigation of the scintillation index of a collimated Gaussian beam, occurring in a turbulent tissue, is investigated by applying adaptive optics. Tilt and astigmatism types of adaptive optics corrections are applied, and the reduction in the tissue scintillations, referenced to no adaptive optics (No AO) scintillations, is reported for tilt only (T Only), astigmatism only (A Only), and total (T + A) adaptive optics correction. Reduction in the scintillations is analyzed against the tissue length, Gaussian laser beam source size, wavelength, receiver aperture diameter, and the tissue turbulence parameters, which are the strength coefficient of the refractive-index fluctuations, fractal dimension, characteristic length of heterogeneity, and small length-scale factor. Finally, the adaptive optics effect on the scintillations is reported for some specific tissue types of liver parenchyma (mouse), intestinal epithelium (mouse), and upper dermis (human). (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Structure Functions for Optical Waves in a Complex Medium of Turbulent Biological Tissues
    (Optica Publishing Group, 2022) Ata, Yalcin; Baykal, Yahya; Gokce, Muhsin caner
    Although optical wave propagation is investigated based on the absorption and scattering in biological tissues, the turbulence effect can also not be overlooked. Here, the closed-form expressions of the wave structure func-tion (WSF) and phase structure function (PSF) of plane and spherical waves propagating in biological tissue are obtained to help with future research on imaging, intensity, and coherency in turbulent biological tissues. This paper presents the effect of turbulent biological tissue on optical wave propagation to give a perception of the per-formance of biomedical systems that use optical technologies. The behavior of optical waves in different types of turbulent biological tissues such as a liver parenchyma (mouse), an intestinal epithelium (mouse), a deep dermis (mouse), and an upper dermis (human) are investigated and compared. It is observed that turbulence becomes more effective with an increase in the characteristic length of heterogeneity, propagation distance, and the strength of the refractive index fluctuations. However, an increase in the fractal dimension, wavelength, and small length scale factor has a smaller turbulence effect on the propagating optical wave. We envision that our results may be used to interpret the performance of optical medical systems operating in turbulent biological tissues.(c) 2022 Optica Publishing Group
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Field Correlations of Multimode Optical Beams in Underwater Turbulence
    (Optica Publishing Group, 2024) Baykal, Yahya; Gokce, Muhsin C.; Ata, Yalcin; Gercekcioglu, Hamza
    For multimode optical beams, field correlations at the receiver plane are found in underwater turbulence. Field correlations of single high order beams in underwater turbulence are special cases of our formulation. Variations of field correlations against the underwater turbulence parameters and the diagonal length from various receiver points are examined for different multimode and single high order beams. Stronger underwater turbulence is found to reduce the field correlations of multimode and single high order optical beams. The results will be of help in heterodyne detection analysis and fiber coupling efficiency in an underwater medium experiencing turbulence. (c) 2024 Optica Publishing Group
  • Article
    Citation - WoS: 3
    Citation - Scopus: 2
    Correlations of Multimode Optical Incidences in a Turbulent Biological Tissue
    (Optica Publishing Group, 2023) Gokce, Muhsin Caner; Gerekcioglu, Hamza; Ata, Yalin; Baykal, Yahya; Gerçekcioğlu, Hamza
    In a turbulent biological tissue, field correlations at the observation plane are found when a multimode optical incidence is used. For different multimode structures, variations of the multimode field correlations are evaluated against the biological tissue turbulence parameters, i.e., the strength coefficient of the refractive-index fluctuations, fractal dimension, characteristic length of heterogeneity, and the small length-scale factor. Using a chosen multimode content, for specific biological tissue types of liver parenchyma (mouse), intestinal epithelium (mouse), upper dermis (human), and deep dermis (mouse), field correlations are evaluated versus the strength coefficient of the refractive-index fluctuations and small length-scale factor. Again, with a chosen multimode content, behavior of the field correlations is studied against the strength coefficient of the refractive-index fluctuations for various diagonal lengths and the transverse coordinate at the observation plane. Finally, the field correlation versus the strength coefficient of the refractive-index fluctuations is reported for different single modes, which are special cases of multimode excitation. This topic is being reported in the literature for the first time, to our knowledge, and the presented results can be employed in many important biological tissue applications. (c) 2023 Optica Publishing
  • Article
    Citation - WoS: 7
    Citation - Scopus: 8
    Field Correlations of Partially Coherent Optical Beams in Underwater Turbulence
    (Optica Publishing Group, 2022) Baykal, Yahya; Gercekcioglu, Hamza
    Field correlations of partially coherent optical beams at the receiver plane are formulated and evaluated in underwater turbulence. Variations of the field correlations are examined against changes in the degree of source coherence, diagonal length from the receiver point, receiver point, propagation distance, source size, ratio of temperature to salinity contributions to the refractive index spectrum, rate of dissipation of mean-squared temperature, and rate of dissipation of kinetic energy per unit mass of fluid. Under any underwater turbulence and link conditions, it is found that field correlations at the receiver plane reduce when the optical source becomes less coherent. (c) 2022 Optica Publishing Group