Elektronik ve Haberleşme Mühendisliği Bölümü

Permanent URI for this communityhttps://hdl.handle.net/20.500.12416/14

Browse

Now showing 1 - 3 of 3

Citation Count: Baykal, Yahya, "Adaptive Optics Correction of Scintillation in Underwater Medium", Journal of Modern Optics, Vol. 67, No. 3, pp. 220-225, (2020).
Adaptive Optics Correction of Scintillation in Underwater Medium
(Taylor&Francis LTD, 2020) Baykal, Yahya; 7812
Adaptive optics correction of the scintillation index of a Gaussian laser beam in underwater turbulence is studied. To introduce the adaptive optics correction, filter functions providing the piston, tilt and astigmatism effects are adapted to promote the spectrum of underwater turbulence. The reduction of the scintillation index due to the individual piston, tilt, astigmatism effects and their sum is examined versus the ratio of temperature to salinity contributions to the refractive index spectrum, the rate of dissipation of mean squared temperature, the rate of dissipation of kinetic energy per unit mass of fluid, receiving aperture diameter, source size, link length and the wavelength. For any value of underwater turbulence parameter, the most effective adaptive optics corrections are found to be the piston, tilt and astigmatism, respectively.
Citation Count: Arpali, Serap Altay...et al. "High-throughput screening of large volumes of whole blood using structured illumination and fluorescent on-chip imaging", Lab On A Chıp, Vol. 12, pp. 4968-4971, (2012)
High-Throughput Screening of Large Volumes of Whole Blood Using Structured Illumination and Fluorescent On-Chip Imaging
(Royal Soc Chemistry,, 2012) Altay Arpalı, Serap; Arpalı, Çağlar; Coşkun, Ahmet F.; Chiang, Hsin-Hao; Özcan, Aydoğan; 51304
Undiluted blood samples are difficult to image in large volumes since blood constitutes a highly absorbing and scattering medium. As a result of this limitation, optical imaging of rare cells (e.g., circulating tumour cells) within unprocessed whole blood remains a challenge, demanding the use of special microfluidic technologies. Here we demonstrate a new fluorescent on-chip imaging modality that can rapidly screen large volumes of absorbing and scattering media, such as undiluted whole blood samples, for detection of fluorescent micro-objects at low concentrations (for example <= 50-100 particles/mL). In this high-throughput imaging modality, a large area microfluidic device (e.g., 7-18 cm(2)), which contains for example similar to 0.3-0.7 mL of undiluted whole blood sample, is directly positioned onto a wide-field opto-electronic sensor-array such that the fluorescent emission within the microchannel can be detected without the use of any imaging lenses. This microfluidic device is then illuminated and laterally scanned with an array of Gaussian excitation spots, which is generated through a spatial light modulator. For each scanning position of this excitation array, a lensfree fluorescent image of the blood sample is captured using the opto-electronic sensor-array, resulting in a sequence of images (e.g., 144 lensfree frames captured in similar to 36 s) for the same sample chip. Digitally merging these lensfree fluorescent images based on a maximum intensity projection (MIP) algorithm enabled us to significantly boost the signal-to-noise ratio (SNR) and contrast of the fluorescent micro-objects within whole blood, which normally remain undetected (i.e., hidden) using conventional uniform excitation schemes, involving plane wave illumination. This high-throughput on-chip imaging platform based on structured excitation could be useful for rare cell research by enabling rapid screening of large volume microfluidic devices that process whole blood and other optically dense media.
Citation Count: Günay, Osman; Töreyin, Behçer Uğur; Çetin, Ahmet Enis (2011). "Online adaptive decision fusion framework based on projections onto convex sets with application to wildfire detection in video", Optical Engineering, Vol. 50, No. 2.
Online adaptive decision fusion framework based on projections onto convex sets with application to wildfire detection in video
(2011) Günay, Osman; Töreyin, Behçer Uğur; Çetin, Ahmet Enis; 19325
t. In this paper, an online adaptive decision fusion framework is developed for image analysis and computer vision applications. In this framework, it is assumed that the compound algorithm consists of several sub-algorithms, each of which yields its own decision as a real number centered around zero, representing the confidence level of that particular sub-algorithm. Decision values are linearly combined with weights that are updated online according to an active fusion method based on performing orthogonal projections onto convex sets describing sub-algorithms. It is assumed that there is an oracle, who is usually a human operator, providing feedback to the decision fusion method. A video-based wildfire detection system is developed to evaluate the performance of the algorithm in handling the problems where data arrives sequentially. In this case, the oracle is the security guard of the forest lookout tower verifying the decision of the combined algorithm. Simulation results are presented.

Browse

Browsing Elektronik ve Haberleşme Mühendisliği Bölümü by Department "Çankaya Üniversitesi, Mühendislik Fakültesi, Elektrik Elektronik Mühendisliği Bölümü"