Elektronik ve Haberleşme Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/260
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Conference Object Citation - WoS: 2Bit Error Rates for Focused General-Type Beams(Electromagnetics Acad, 2009) Arpali, Serap; Arpali, Serap Altay; Baykal, Yahya Kemal; Baykal, Yahya; Elektrik-Elektronik Mühendisliği; Elektronik ve Haberleşme MühendisliğiUsing the scintillation index of general beam formulation, bit error rate (BER) is investigated for focused Gaussian, cos-Gaussian, cosh-Gaussian and annular beams in weak atmospheric turbulence. We have employed our previously derived formulation of the scintillation index of these beams by Rytov method. Rytov method scintillation theory is known to yield accurate results for focused beams on horizontal paths under certain regions. Therefore we find the scintillation indices of the mentioned beams for the valid region. Using the log-normal distributed intensity, BER values versus signal-to-noise ratio (SNR) are calculated for Gaussian, cos-Gaussian, cosh-Gaussian and annular beams. In our study, the focal lengths (radius of curvature) of all the mentioned focused beams are equal to the propagation distance. The improvement of BER is observed for variations of propagation length, source size and wavelength of operation. Based on these parameters, BER values of Gaussian, cos-Gaussian, cosh-Gaussian and annular beams are compared. BER values we found for the focused Gaussian, cos-Gaussian, cosh-Gaussian and annular beams decrease with increasing source sizes. Likewise, BER values of focused Gaussian, cos-Gaussian, cosh-Gaussian and annular beams decrease with increasing wavelength. The focused annular beam attains the lowest BER value for small source sizes and long propagation distances. Moreover, BER for focused beams is compared with their collimated counterparts. We observe that focused beams have lower BER values than the collimated beams on horizontal paths. Our formulation can easily be extended to cover corresponding higher order beams, however in this paper we concentrate mainly on the zero order beams.Conference Object Fluorescent On-Chip Imager by Using a Tunable Absorption Filter(Ieee, 2017) Arpali, Caglar; Yıldırım, Ender; Yildirim, Ender; Arpali, Çağlar; Arpali, Serap Altay; Arpali, Serap; Makine Mühendisliği; Mekatronik Mühendisliği; Elektronik ve Haberleşme MühendisliğiArticle Yumuşak Doku İçerisinde Yayılan Küresel Dalganın Performans Analizi(2021) Arpali, Serap AltayBu çalışmada, yumuşak doku içerisinde yayılan küresel dalganın performansını analiz edebilmek için, optiksel küresel dalganın bit-hata-olasılığını (BER) inceledik. Bu kapsamda, optiksel küresel dalganın ortalama BER’i (<BER>), yumuşak dokunun kırınım indeksindeki rastgele değişimleri, kaynak ve detektör arasındaki doku uzunluğu, büyük ölçekli doku türbülansı gibi değişik doku ve türbülans parametrelerine bağlı olarak ayrıntılı olarak çalışılmıştır. Çalışmanın sonucunda doku türbülansının büyük ölçek değeri, doku uzunluğu ve yumuşak dokunun kırınım indeksindeki rastgele değişimleri arttıkça <BER> değeri artmıştır. Ayrıca optiksel küresel dalganın <BER> değerleri üstel ölçek kuralının sınırları içinde belirlenen eğimin yarı değerinin farklı büyüklükleri için incelenmiştir. Üstel ölçek kuralının sınırları içinde belirlenen eğimin yarı değerinin farklı büyüklüklerinin azalan değerleri için küresel dalganın <BER>’nin düştüğü gözlemlenmiştir.Article Citation - WoS: 8Citation - Scopus: 7Bit Error Rate of a Gaussian Beam Propagating Through Biological Tissue(Taylor & Francis Ltd, 2020) Arpali, Serap Altay; Arpali, Caglar; Baykal, YahyaThe scintillation index and bit error rate (BER) of a Gaussian beam propagating in a weakly turbulent soft tissue are formulated and analysed numerically. The scintillation indices are plotted against half of the measured slope in the range of power-law scaling at different tissue parameters, such as the random variations in the refractive index of the tissue, outer scale of the tissue turbulence and the tissue length between the optical source and the detector. Moreover, BERs of Gaussian beams against the signal to noise ratio (SNR) are examined for different tissue parameters. Our graphical results show that the scintillation index and BER increase with larger outer scales, longer tissue lengths and larger random variations in the refractive index of the tissue. In comparison with the spherical wave propagation, it was found that Gaussian beam yields larger scintillation index and BER values.Article Citation - WoS: 48Citation - Scopus: 50High-Throughput Screening of Large Volumes of Whole Blood Using Structured Illumination and Fluorescent On-Chip Imaging(Royal Soc Chemistry, 2012) Arpali, Serap Altay; Arpali, Caglar; Coskun, Ahmet F.; Chiang, Hsin-Hao; Ozcan, AydoganUndiluted 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.Article Citation - WoS: 49Citation - Scopus: 47Scintillation Index of Higher-Order Cos-Gaussian, Cosh-Gaussian and Annular Beams(Taylor & Francis Ltd, 2008) Arpali, Serap Altay; Eyyuboglu, Halil T.; Baykal, YahyaIn this paper, via the generalized beam formulation, we evaluate the scintillation index for higher-order general beams propagating through the weak atmospheric turbulence. The investigated higher-order beam types are cos-Gaussian, cosh-Gaussian and annular beams. The scintillation indices of these beams are plotted with respect to propagation length, source size and order of the beam. According to our graphical outputs, higher-order beams have less on-axis scintillation index than zero-order beams at longer propagation distances. The on-axis scintillation exhibits a slight increase when the order of even-ordered beams is made higher. Moreover, our study on the source size variation shows that, for most of the source size range, cos-Gaussian beams have a lower scintillation index than the other beams.Article Citation - WoS: 22Citation - Scopus: 20Scintillation Index of Optical Spherical Wave Propagating Through Biological Tissue(Taylor & Francis Ltd, 2017) Baykal, Yahya; Arpali, Caglar; Arpali, Serap AltayEffects of the tissue turbulence on the propagation of an optical spherical wave are analysed. For this purpose, scintillation index of an optical spherical wave which is propagating in a soft tissue is formulated and evaluated in weakly turbulent soft tissue. Scintillation index of the optical spherical wave is examined against the changes in the tissue parameters which are the tissue length between the optical spherical wave source and the detector, random variations in the refractive index of the tissue and the outer scale of the tissue turbulence. According to our graphical outputs, it is observed that increase in the random variations of the refractive index of the tissue results in an increase in the scintillation index at a certain realization of the turbulence spectrum. On the other hand, larger outer scales and longer tissue lengths yield larger scintillations. The variation of the scintillation index of the optical spherical wave versus the wavelength is also investigated. It is found that at small tissue lengths, wavelength has almost no effect on the scintillations; however, when the tissue length reaches a certain value, shorter wavelengths give rise to larger intensity fluctuations.Article Citation - WoS: 8Citation - Scopus: 12Implementation and Characterization of an Absorption Filter for On-Chip Fluorescent Imaging(Elsevier Science Sa, 2017) Arpali, Caglar; Arpali, Serap Altay; Yildirim, EnderHere we present fabrication and characterization of an absorption filter with superior roll-on properties and precisely tunable cut-off wavelengths for fluorescent imaging applications in lab-on-a-chip systems. The filters were fabricated by spinning dye doped photopolymer (Orasol Yellow in Norland Optical Adhesive 60) on glass substrates. The fabrication technique allowed us to precisely tune the cut-off wavelength of the filters. We showed that filters with different cut-off in the range of 386 nm-504 nm could be obtained simply by controlling the settling time before spinning. The filters exhibited a steep roll-on from stopband to passband at the cut-off. Transmission in the stopband was observed to be maximum 3% while it was almost constant at 100% in the passband within the range of 220 nm-620 nm. On-chip use of the filters was also demonstrated for imaging particular fluorescent beads. (C) 2016 Elsevier B.V. All rights reserved.Article Citation - WoS: 29Citation - Scopus: 35Ber Evaluations for Multimode Beams in Underwater Turbulence(Taylor & Francis Ltd, 2016) Arpali, Serap Altay; Baykal, Yahya; Arpali, CaglarIn underwater optical communication links, bit error rate (BER) is an important performance criterion. For this purpose, the effects of oceanic turbulence on multimode laser beam incidences are studied and compared in terms of average BER (< BER >), which is related to the scintillation index. Based on the log-normal distribution, < BER > is analysed for underwater turbulence parameters, including the rate of dissipation of the mean squared temperature, the rate of dissipation of the turbulent kinetic energy, the parameter that determines the relative strength of temperature and salinity in driving index fluctuations, the Kolmogorov microscale length and other link parameters such as link length, wavelength and laser source size. It is shown that use of multimode improves the system performance of optical wireless communication systems operating in an underwater medium. For all the investigated multimode beams, decreasing link length, source size, the relative strength of temperature and salinity in driving the index fluctuations, the rate of dissipation of the mean squared temperature and Kolmogorov microscale length improve the < BER >. Moreover, lower < BER > values are obtained for the increasing wavelength of operation and the rate of dissipation of the turbulent kinetic energy in underwater turbulence.Article Citation - WoS: 28Citation - Scopus: 28Bit Error Rates for General Beams(Optical Soc Amer, 2008) Arpali, Serap Altay; Eyyuboglu, Halil T.; Baykal, YahyaIn order to analyze the effect of beam type on free space optical communication systems, bit error rate (BER) values versus signal-to-noise ratio (SNR) are calculated for zero order and higher order general beam types, namely for Gaussian, cos-Gaussian, cosh-Gaussian, and annular beams. BER analysis is based on optical scintillation using log-normal distribution for the intensity, which is valid in weak atmospheric turbulence. BERs for these beams are plotted under variations of propagation length, source size, wavelength of operation, and order of the beam. According to our graphical outputs, at small source sizes and long propagation distances, the smallest BER value is obtained for the annular beam. On the other hand, at large source size and small propagation distance, the smallest BER value is obtained for the cos-Gaussian beam, Moreover, our study of the order of the beam shows that higher order beams have lower BER values than the zero order beams at longer propagation distances. But this drop compared with the order seems to be incremental. (c) 2008 Optical Society of America