Browsing by Author "Arpali, Caglar"

Now showing 1 - 16 of 16

Citation - WoS: 18
Citation - Scopus: 19
A Comparison of Iterative Fourier Transform Algorithms for Image Quality Estimation
(Optical Soc Japan, 2018) Alsaka, Dina Yaqoob; Arpali, Caglar; Arpali, Serap Altay; 20809
A comparison was established between two iterative Fourier transform algorithms (IFTAs), such as the original Gerchberg-Saxton (GS) and the mixed-region amplitude freedom (MRAF) algorithms, for the hologram reconstruction of different target images through the full reference image quality estimation (IQE) and pixel homogeneity in the Fourier plane presented theoretically and experimentally. The comparison was applied depending upon both algorithms based on a computer-generated hologram (CGH) implemented utilizing a reflective phase-modulated liquid-crystal spatial light modulator (LC-SLM) to obtain the digital kinoform holograms of the desired intensity distributions. These digital holograms were applied to reconstruct the intensity patterns for 852 nm, which represents a laser beam source. The theoretical and experimental results of the reconstructed patterns obtained using the MRAF algorithm were found to be smoother and better than the patterns obtained using the GS algorithm. Unmodulated light beam (dc term) is removed from the reconstructed patterns attributed to digital kinoform holograms of MRAF algorithm as an alternative to the theoretical and experimental results without using any additional optic equipment at the light path. Moreover, this paper discussed the full reference objective quality estimations, such as mean square error (MSE), peak signal-to-noise ratio (PSNR), structural content (SC), normalized absolute error (NAE), normalized cross correlation (NK), and homogeneity of pixels, through the contrast (Cont) and inverse difference moment (IDM) for numerical and experimental results. According to the two desired intensity distributions processed theoretically and experimentally, the results of MRAF algorithm were found to be in the highly accurate recovered phase, the quality of image was enhanced, and the dc term was decreased. Image quality estimation of full reference objective relay on the feedback algorithms experimental attestation has not been implemented yet.
Citation - WoS: 0
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.
Citation - WoS: 4
Citation - Scopus: 3
Arbitrary laser beam propagation in free space
(Elsevier Science Bv, 2009) Arpali, Caglar; Baykal, Yahya; Nakiboglu, Cem; 7812
The propagation of arbitrary laser beams in free space is examined. For this purpose, starting with an incident field of arbitrary field distribution, the intensity at the receiver plane is formulated via Huygens Fresnel diffraction integral. Arbitrary source field profile is produced by decomposing the source into incremental areas (pixels). The received field through the propagation in free space is found by superposing the contributions from all source incremental areas. The proposed method enables us to evaluate the received intensity originating from any type of source field. Using the arbitrary beam excitation, intensity of various laser beams such as cos-Gaussian, cosh-Gaussian, general type beams are checked to be consistent with the already existing results in literature, and the received intensity distributions are obtained for some original arbitrary beam field profiles. Our received intensity formulation for the arbitrary source field profiles presented in this paper can find application in optics communication links, reflection from rough surfaces, optical cryptography and optical imaging systems. (C) 2009 Elsevier B.V. All rights reserved.
Citation - WoS: 1
Citation - Scopus: 0
Average received intensity for optical beam of arbitrary field profile after propagation in turbulent atmosphere
(Spie-int Soc Optical Engineering, 2009) Arpali, Caglar; Baykal, Yahya; 20809; 7812
Employing our previously obtained formulation of the average received intensity for arbitrary optical beam in turbulent atmosphere, intensity patterns of already known and new source profiles are obtained. Arbitrary beam is defined as an incidence having arbitrary source field distribution which is produced by decomposing the source into pixels and assigning the related field to each pixel. For each source field originating from each pixel, incremental received field is found and the total received field is obtained by superposing the contributions from all the incremental received fields. Using the mentioned formula governing the arbitrary beam excitation in turbulence, average received intensity patterns for various types of beams such as cos-Gaussian, cosh-Gaussian, higher-order annular, flat-topped, general type and arbitrary beams are obtained. Our results can be applied in atmospheric optics communication links, reflection from rough surfaces, optical cryptography, optical imaging systems and propagation of partially coherent light.
Citation - WoS: 29
Citation - Scopus: 35
BER evaluations for multimode beams in underwater turbulence
(Taylor & Francis Ltd, 2016) Arpali, Serap Altay; Baykal, Yahya; Arpali, Caglar; 7812
In 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.
Citation - WoS: 2
Citation - Scopus: 3
BER for Higher Order Laser Modes in Optical Wireless Underwater Communications
(Ieee, 2016) Arpali, Serap Altay; Baykal, Yahya; Arpali, Caglar; 51304; 7812; 20809
Average bit error rate () of an underwater optical communication system is analyzed for higher order laser beams. For this purpose, the effects of oceanic turbulence parameters and link parameters on single mode higher order laser beams are investigated.
Citation - WoS: 8
Citation - Scopus: 7
Bit Error Rate of A Gaussian Beam Propagating Through Biological Tissue
(Taylor & Francis Ltd, 2020) Arpali, Serap Altay; Arpali, Caglar; Baykal, Yahya; 7812; 51304; 20809
The 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.
Citation - WoS: 6
Citation - Scopus: 6
Dynamic flat-topped laser beam shaping method using mixed region amplitude freedom algorithm
(Springer Heidelberg, 2022) Alsaka, Dina Yaqoob; Arpali, Caglar; Arpali, Serap Altay; Altemimi, Mohammed Fawzi; 20809; Mekatronik Mühendisliği
A dynamic beam shaping method is proposed for the generation of flat-top beams (FTBs) in the far field. Using the mixed-region amplitude freedom algorithm, this new method is used to design the required phase distribution encoded on a spatial light modulator for the generation of FTB profiles. The characteristics of these new beam shaping methods are used as beam parameters, such as the laser beam size, the beam intensity of square FTBs, and the root-mean-square error (RMSE). Using our proposed method, the theoretical performance of beam intensity shaping is improved to an RMSE < 0.02 with a minimum number of iterations of phase reconstruction. Using the phase hologram of dynamic beam shaping, theoretical and experimental comparisons of edge steepness and plateau uniformity were established for the square FTBs of variable beam sizes. It is shown that the dynamic beam shaping of FTBs can produce high intensity uniformity in the plateau region with steep edges, which makes it an effective tool, especially for laser machining applications.
Citation - WoS: 4
Citation - Scopus: 11
Effects of Focused and Collimated Laser Beams on the Performance of Underwater Wireless Optical Communication Links
(Ieee, 2015) Keskin, Aysan; Catmakas, Omer Kemal; Genc, Fatih; Baykal, Yahya; Arpali, Serap Altay; Arpali, Caglar; Elektronik ve Haberleşme Mühendisliği
In this paper, the optical transmittance and bit error rate (BER) of focused and collimated laser beams are experimentally examined in an underwater optical wireless communication link with different water types. The water types used are fresh water, salty water and their variations with maalox in order to obtain turbid water. In bit error rate (BER) analysis, on-off keying (OOK) is used together with Bose-Chaudhuri-Hocquenghem (BCH) and convolutional codes. Results show that salt and maalox content decreases the transmittance, the convolution codes have better BER performance than BCH codes under the same modulation scheme (i.e., OOK) and focusing improves both the transmittance and BER performance as compared to collimated beams.
Citation - WoS: 135
Citation - Scopus: 135
Flat topped beams and their characteristics in turbulent media
(Optical Soc Amer, 2006) Eyyuboglu, Halil Tanyer; Arpali, Caglar; Baykal, Yahya Kemal; 7688; 7812; Elektrik-Elektronik Mühendisliği
The source and receiver plane characteristics of flat topped ( FT) beam propagating in turbulent atmosphere are investigated. To this end, source size, beam power and M(2) factor of source plane FT beam are derived. For a turbulent propagation medium, via Huygens Fresnel diffraction integral, the receiver plane intensity is found. Power captured within an area on the receiver plane is calculated. Kurtosis parameter and beam size variation along the propagation axis are formulated. Graphical outputs are provided displaying the variations of the derived source and receiver plane parameters against the order of flatness and propagation length. Analogous to free space behavior, when propagating in turbulence, the FT beam first will form a circular ring in the center. As the propagation length increases, the circumference of this ring will become narrower, giving rise to a downward peak emerging from the center of the beam, eventually turning the intensity profile into a pure Gaussian shape. (c) 2006 Optical Society of America.
Citation - WoS: 0
Citation - Scopus: 0
Fluorescent on-chip imager by using a tunable absorption filter
(Ieee, 2017) Arpali, Caglar; Yildirim, Ender; Arpali, Serap Altay; 20809; 31835; 51304; Makine Mühendisliği
Citation - WoS: 0
Citation - Scopus: 0
High-Throughput Screening of Blood Samples Based on Structured Illumination On-Chip Imaging
(Ieee, 2013) Arpali, Serap Altay; Arpali, Caglar; Coskun, Ahmet F.; Chiang, Hsin-Hao; Ozcan, Aydogan
We demonstrate a high-throughput fluorescent on-chip imaging platform, using structured illumination that can rapidly screen large volumes of scattering media such as undiluted whole blood samples (e.g., similar to 0.3-0.7 mL) for detection of fluorescent micro-objects at low concentrations (e.g., <= 50-100 particles/mL). This imaging modality might especially be useful for rare cell applications involving whole blood samples, such as detection of circulating tumor cells.
Citation - WoS: 47
Citation - Scopus: 50
High-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, Aydogan; 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 - WoS: 6
Citation - Scopus: 10
Implementation and characterization of an absorption filter for on-chip fluorescent imaging
(Elsevier Science Sa, 2017) Yildirim, Ender; Arpali, Caglar; Arpali, Serap Altay; 31835; 20809; 51304; Makine Mühendisliği
Here 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.
Citation - WoS: 22
Citation - Scopus: 20
Scintillation index of optical spherical wave propagating through biological tissue
(Taylor & Francis Ltd, 2017) Baykal, Yahya; Arpali, Caglar; Arpali, Serap Altay; 7812; 20809; 51304
Effects 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.
Citation - WoS: 77
Citation - Scopus: 73
Simulator for general-type beam propagation in turbulent atmosphere
(Optical Soc Amer, 2006) Arpali, Caglar; Yazicioglu, Canan; Eyyuboglu, Halil Tanyer; Arpali, Serap Altay; Baykal, Yahya; 7688; 7812; 51304
A simulator is designed in MATLAB code which gives the propagation characteristics of a general-type beam in turbulent atmosphere. When the required source and medium parameters are entered, the simulator yields the average intensity profile along the propagation axis in a video format. In our simulator, the user can choose the option of a "user defined beam" in which the source and medium parameters are selected as requested by the user by entering numerical values in the relevant menu boxes. Alternatively, the user can proceed with the option of "pre-defined beam" in which the average intensity profiles of beams such as annular, cos-Gaussian, sine-Gaussian, cosh-Gaussian, sinh-Gaussian, their higher-order counterparts and flat-topped can be observed as they propagate in a turbulent atmosphere. Some samples of the simulator output are presented. (c) 2006 Optical Society of America