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Wyszukujesz frazę "phase retrieval" wg kryterium: Temat


Wyświetlanie 1-9 z 9
Tytuł:
The effect of noise, a constant background, and bit depth on the phase retrieval of pure phase objects
Autorzy:
Karitans, Varis
Tokmakovs, Andrejs
Antonuka, Adele
Tematy:
phase retrieval
phase problem
diffraction
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Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:
https://bibliotekanauki.pl/articles/1835795.pdf  Link otwiera się w nowym oknie
Opis:
In the current study, we investigate the effect of uniform white noise, Poisson noise and a constant background on the phase retrieval of pure phase objects. We also study the influence of the aforementioned factors on phase retrieval at different bit depths of intensity measurements. An algorithm called PhaseLift is used for phase retrieval as it requires a small number of modulating masks and can retrieve the phase of an object from sparse intensity measurements of low bit depth. A test object is modulated by eight random masks generated from a single mask and the phase of the object is retrieved from coded diffraction patterns. Different levels of uniform white noise, Poisson noise and constant background are superimposed on the diffraction patterns and the root-mean-square error (RMSE) of the retrieved object is calculated at each level. The results suggest that Poisson noise and a constant background at the same level cause similar RMSE compared to uniform white noise. Lowering the bit depth from 18-bits to 14-bits resulted in the decrease of the RMSE caused by Poisson noise and a constant background. We conclude that the effects of noise and constant background can be reduced by lowering the bit depth.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two-step blind phase-shifting interferometry based on the extreme value of interference and least-squares iterative algorithm
Autorzy:
Xu, Xiaoqing
Xie, Ming
Ji, Ying
Wang, Yawei
Tematy:
interferometry
phase retrieval
fringe analysis
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Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:
https://bibliotekanauki.pl/articles/2033890.pdf  Link otwiera się w nowym oknie
Opis:
To improve the measuring accuracy in two-step phase-shifting interferometry (PSI), a new approach combining the extreme value of interference (EVI) and the least-squares iterative algorithm (LSIA) is proposed to extract the phase from two-frame blind phase-shifting interferograms. This method first evaluates the phase shift between two interferograms by the EVI algorithm, and then constructs the fitted interferogram by the addition of two interferograms after filtering the corresponding background intensities, so the phase with high precision can be retrieved by combining two real interferograms and this fitted interferogram using the LSIA method. The proposed algorithm expands the flexibility of the LSIA method and has the high-precision performance compared with the existing algorithms in two-step PSI. Simulation and experiment are performed to verify the feasibility of the proposed algorithm.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase retrieval without phase unwrapping for white blood cells in deep-learning phase-shifting digital holography
Autorzy:
Jin, Shuyang
Xu, Xiaoqing
Chen, Jili
Ni, Yudan
Tematy:
digital holography
phase retrieval
deep learning
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Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:
https://bibliotekanauki.pl/articles/2202768.pdf  Link otwiera się w nowym oknie
Opis:
Phase retrieval and phase unwrapping are the two important problems for enabling quantitative phase imaging of cells in phase-shifting digital holography. To simultaneously cope with these two problems, a deep-learning phase-shifting digital holography method is proposed in this paper. The proposed method can establish the continuous mapping function of the interferogram to the ground-truth phase using the end-to-end convolutional neural network. With a well-trained deep convolutional neural network, this method can retrieve the phase from one-frame blindly phase-shifted interferogram, without phase unwrapping. The feasibility and applicability of the proposed method are verified by the simulation experiments of the microsphere and white blood cells, respectively. This method will pave the way to the quantitative phase imaging of biological cells with complex substructures.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fully-phase optical image encryption in diffractive-imaging scheme with QR-code-based random illumination
Autorzy:
Wang, Z.
Zhang, Y.
Gong, Q.
Li, S.
Qin, Y.
Tematy:
optical encryption
diffractive imaging
fully phase
phase retrieval algorithm
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Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:
https://bibliotekanauki.pl/articles/174126.pdf  Link otwiera się w nowym oknie
Opis:
Based on a fully phase encoding and phase retrieval algorithm, a diffractive-imaging-based optical encryption scheme with random illumination is proposed. In the encryption process, a QR code image is placed in the optic path to modulate the incident light and thus generate a random illumination, which has been demonstrated to enable the proposed scheme to resist the multi-slice ptychographic phase retrieval algorithm attack. The plaintext is phase-encoded, and then encrypted by two random phase masks. The diffraction pattern in the output plane is recorded as ciphertext by a CCD camera. For decryption, an iterative phase retrieval algorithm with median filtering operation is implemented. Simulation results demonstrate the effectiveness, security, and robustness of the proposal.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fast phase reconstruction in off-axis digital holography with zero-order term suppression
Autorzy:
Luan, Guangyu
Shan, Mingguang
Zhong, Zhi
Xia, Bai
Tematy:
digital holography
phase retrieval
off-axis
zero-order suppression
filtering
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Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:
https://bibliotekanauki.pl/articles/1835806.pdf  Link otwiera się w nowym oknie
Opis:
A fast phase reconstruction method (FPRM) employing a free-sample hologram can improve the efficiency of phase reconstruction in off-axis digital holography. However, the space-bandwidth product is still confined by spectrum aliasing in the hologram owing to the zero-order term. In this paper, we propose an FPRM that features an efficient zero-order term suppression method called the average gray that can eliminate spectrum shifting. We can implement phase reconstruction by considering both speed and the space-bandwidth product. We verified the validity of our approach for off-axis digital holography using laser and white-light illumination.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simultaneous intensity projection for projector response computation with application to an active radiometric calibration
Autorzy:
Filio-Aguilar, Pedro-David
López-García, Lourdes
Rueda-Paz, Juvenal
Ávila-Aoki, Manuel
Tematy:
camera-projector compensation
digital fringe projection
phase retrieval
3D imaging
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Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:
https://bibliotekanauki.pl/articles/2172863.pdf  Link otwiera się w nowym oknie
Opis:
One of the most important sources of errors in digital fringe projection (DFP) systems is the nonlinearity in the response of the projector when it uses the three-step phase retrieval algorithm. Thus, it is necessary to increase the accuracy without affecting the efficiency. In this sense, the radiometric rectification methods are used. In this paper, an active radiometric rectification method for digital fringe projection is proposed. This proposal consists in two improvements of traditional active techniques: first, parallel intensity projection is used to obtain the projector response which requires only four dot patterns; and second, a method is provided for the calculation of the inverse polynomial that guarantees symmetry with respect to the response of the projector. Experimental results, in a digital fringe projection system, show that the root-mean-square phase error improves 6.3 times using this proposal.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Deflectometry for phase retrieval using a composite fringe
Autorzy:
Liu, T.
Zhou, C.
Liu, Y
Si, S
Lei, Z.
Tematy:
wavefront measurement
fringe analysis
phase retrieval
fast Fourier transform (FFT)
multifrequency heterodyne principle
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Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:
https://bibliotekanauki.pl/articles/173892.pdf  Link otwiera się w nowym oknie
Opis:
An improved deflectometry for wavefront measurement using a composite fringe is proposed to reduce the projection fringes and improve the accuracy. The single composite fringe contains four fringes in different directions. It goes through the tested objects and then is captured by a CCD camera. Two high frequency orthogonal fringe patterns and two single period orthogonal fringe patterns can be obtained from the composite fringe by fast Fourier transform. The unwrapping of the wrapped phase of the high frequency fringe is accomplished by the corresponding single period fringe using a heterodyne method. The wavefront is reconstructed by the integration of partial derivatives. Using only one fringe, the proposed method is more applicable to dynamic wavefront measurement. The experimental results demonstrate that the proposed method can retrieve the complex wavefronts more accurately.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Retrieval of Chern numbers from experimental data
Metoda wyznaczania liczb Cherna z danych eksperymentalnych
Autorzy:
Szołdra, Tomasz
Opis:
W niniejszej pracy zaproponowano nową metodę pomiaru niezmiennika topologicznego pasma energetycznego w nietrywialnych topologicznie modelach wielopasmowych poprzez pomiar gęstości chmury ultrazimnych bozonów po czasie przelotu. Dzięki użyciu algorytmu odzyskiwania fazy możliwa jest całkowita rekonstrukcja stanów własnych Hamiltonianu w pierwszej strefie Brillouina. Liczba Cherna może zostać z nich wyliczona, co zostało potwierdzone symulacjami numerycznymi. Przeprowadzono analizę wpływu oganiczeń eksperymentalnych na otrzymane wartości liczby Cherna.
We propose a novel method to measure the topological invariant of the energy band in topological multiband models by time-of-flight atomic density imaging of ultracold bosonic clouds. Using phase retrieval algorithms, we are able to reconstruct the complete complex-valued eigenstate vectors of the system in the Brillouin zone. Chern number can be then calculated what is proven by numerical simulations. Finally, robustness of the method against experimental limitations is analyzed.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Inne
Tytuł:
Two-step dual-wavelength interferometry for surface relief retrieval
Autorzy:
Kmet, Arkady B.
Muravsky, Leonid I.
Voronyak, Taras I.
Stasyshyn, Ihor V.
Tematy:
dual-wavelength interferometry
two-step phase shifting interferometry
blind phase shift
surface relief retrieval
areal surface roughness
areal waviness
phase map
Pokaż więcej
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:
https://bibliotekanauki.pl/articles/173569.pdf  Link otwiera się w nowym oknie
Opis:
The new two-step dual-wavelength interferometry method that uses only two pairs of interferograms for surface relief retrieval is proposed. In this method, two interferograms in each pair are differed only by an arbitrary phase shift of a reference wave. The method allows using only one out-of-plane shift of a reference wave to record each second interferogram in both pairs, since arbitrary phase shifts between interferograms in each pair can be defined by calculation of the correlation coefficient between two interferograms. This method can extract separately areal surface roughness and areal waviness phase maps from a phase map of the total surface relief and reduce errors produced during the surface relief retrieving. Computer simulation and experimental verification have confirmed the reliability of the proposed method.
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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