Yazar "Tiryaki, Erhan" seçeneğine göre listele

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    3D Profile Measurements of Objects by Using Zero Order Generalized Morse Wavelet
    (Amer Inst Physics, 2017) Koçahan, Özlem; Durmuş, Çagla; Elmas, Merve Naz; Coşkun, Emre; Tiryaki, Erhan; Özder, Serhat
    Generalized Morse wavelets are proposed to evaluate the phase information from projected fringe pattern with the spatial carrier frequency in the x direction. The height profile of the object is determined through the phase change distribution by using the phase of the continuous wavelet transform. The phase distribution is extracted from the optical fringe pattern choosing zero order Generalized Morse Wavelet (GMW) as a mother wavelet. In this study, standard fringe projection technique is used for obtaining images. Experimental results for the GMW phase method are compared with the results of Morlet and Paul wavelet transform.
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    A Simulation Study for Determination of Refractive Index Dispersion of Dielectric Film from Reflectance Spectrum by Using Paul Wavelet
    (Amer Inst Physics, 2017) Tiryaki, Erhan; Coşkun, Emre; Koçahan, Özlem; Özder, Serhat
    In this work, the Continuous Wavelet Transform (CWT) with Paul wavelet was improved as a tool for determination of refractive index dispersion of dielectric film by using the reflectance spectrum of the film The reflectance spectrum was generated theoretically in the range of 0.8333 - 3.3333 mu m wavenumber and it was analyzed with presented method. Obtained refractive index determined from various resolution of Paul wavelet were compared with the input values, and the importance of the tunable resolution with Paul wavelet was discussed briefly. The noise immunity and uncertainty of the method was also studied.
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    An Improved Method for Determination of Refractive Index of Dielectric Films from Reflectance Spectrum by Using the Generalized Morse Wavelet
    (Sciendo, 2021) Tiryaki, Erhan; Koçahan, Özlem; Özder, Serhat
    The Generalized Morse Wavelet (GMW) algorithm was adapted to determine the refractive index of dielectric film from the reflectance spectrum. A theoretically generated reflectance spectrum in the range of 300-1200 nm wavelength was analyzed by the Continuous Wavelet Transform (CWT) and the refractive index dispersion was obtained by the mentioned method. In addition, a noisy reflectance spectrum was analyzed to show the advantages of the CWT method. Refractive index dispersions calculated by the Morlet and the Paul wavelet were compared to GMW at the end of the study.
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    Determination of phase from the ridge of CWT using generalized Morse wavelet
    (Iop Publishing Ltd, 2018) Koçahan, Özlem; Tiryaki, Erhan; Coşkun, Emre; Özder, Serhat
    The selection of wavelet is an important step in order to determine the phase from the fringe patterns. In the present work, a new wavelet for phase retrieval from the ridge of continuous wavelet transform (CWT) is presented. The phase distributions have been extracted from the optical fringe pattern by choosing the zero order generalized morse wavelet (GMW) as a mother wavelet. The aim of the study is to reveal the ways in which the two varying parameters of GMW affect the phase calculation. To show the validity of this method, an experimental study has been conducted by using the diffraction phase microscopy (DPM) setup; consequently, the profiles of red blood cells have been retrieved. The results for the CWT ridge technique with GMW have been compared with the results for the Morlet wavelet and the Paul wavelet; the results are almost identical for Paul and zero order GMW because of their degree of freedom. Also, for further discussion, the Fourier transform and the Stockwell transform have been applied comparatively. The outcome of the comparison reveals that GMWs are highly applicable to the research in various areas, predominantly biomedicine.
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    Optical Phase Distribution Evaluation by Using Zero Order Generalized Morse Wavelet
    (Amer Inst Physics, 2017) Koçahan, Özlem; Elmas, Merve Naz; Durmuş, Çagla; Coşkun, Emre; Tiryaki, Erhan; Özder, Serhat
    When determining the phase from the projected fringes by using continuous wavelet transform (CWT), selection of wavelet is an important step. A new wavelet for phase retrieval from the fringe pattern with the spatial carrier frequency in the x direction is presented. As a mother wavelet, zero order generalized Morse wavelet (GMW) is chosen because of the flexible spatial and frequency localization property, and it is exactly analytic. In this study, GMW method is explained and numerical simulations are carried out to show the validity of this technique for finding the phase distributions. Results for the Morlet and Paul wavelets are compared with the results of GMW analysis.
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    Quantitative Phase Imaging of Red Blood Cell by Diffraction Phase Microscopy
    (IEEE, 2017) Koçahan, Özlem; Tiryaki, Erhan; Durmuş, Çagla; Elmas, Merve Naz; Coşkun, Emre; Özder, Serhat
    Diffraction phase microscopy maintains the single shot measurement and low speckle noise associated with white light. A microscope with halogen lamp and a Mach-Zehnder interferometer were combined to obtain images of red blood cell with fringe pattern. From these images, the phase values were retrieved by using continuous wavelet transform (CWT) phase method. In the analysis of CWT, Paul wavelet is chosen as a mother wavelet. Experimental results of the CWT phase method with Paul wavelet are discussed at the end of the study.
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    Quantitative phase imaging of thin film surface
    (Polska Akademia Nauk, 2021) Tiryaki, Erhan; Koçahan, Özlem; Özder, Serhat
    In this study, the white light diffraction phase microscopy and the generalized Morse wavelet are proposed to achieve practical and precise measurement of a thin film surface. The white light diffraction phase microscopy provides low speckle noise and single-shot measurement, and thus it has been used to produce an image with interference fringes from the surface of a thin film. Relying on produced interferogram, quantitative phase information of the thin film surface has been obtained using the continuous wavelet transform. In the calculation of the quantitative phase, in many studies the continuous wavelet transform method with different wavelets is preferred. The Morlet wavelet is a commonly used one with a fixed resolution. An alternative approach is proposed using the generalized Morse wavelet capable of controlling the resolution. It has an additional advantage of varying the two parameters, thus improving the sensitivity of phase calculation. Results of the generalized Morse wavelet were compared with the Morlet and Paul wavelets which also have one varying parameter. For the determination of the thin film surface profile, besides the white light diffraction phase microscopy, surfaces have been investigated by a Dektak stylus profilometer and a scanning electron microscope. In this way, it was possible to observe the difference between the most commonly used methods with regard to the imaging of thin film surfaces. The application of the white light diffraction phase microscopy with the generalized Morse wavelet was compared with the common microscopy techniques for studying thin film surfaces, and experimental results were discussed at the end of the study. © 2021 Polish Academy of Sciences. All rights reserved.
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    The zero order generalized Morse wavelet method to determine the refractive index and extinction coefficient dispersions of an absorbing film
    (Elsevier B.V., 2019) Koçahan, Özlem; Coşkun, E.; Tiryaki, Erhan; Özder, Serhat
    The zero order generalized Morse wavelet was proposed as a method to determine the refractive index and extinction coefficient dispersions of an absorbing thin film in the visible and near infrared regions at room temperature. The generalized Morse wavelet has two degree of freedom and the advantages and disadvantages of additional degree of freedom were discussed in the simulation works. The simulation studies were based on the mean relative error and Cauchy coefficients comparisions, and accuracy of the calculated refractive index was improved by the presented method, were compared with the Morlet wavelet and Paul wavelet. Also, the noise immunity of the method was discussed. The experimental validity of the method was tested on a cadmium sulfide absorbing thin film and the calculated refractive index were cross checked with the value of envelope method and literature. © 2019 Elsevier B.V.