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Wyświetlanie 1-14 z 14
Tytuł:
Propagation properties of anomalous hollow vortex beam in uniaxial crystal orthogonal to the optical axis
Autorzy:
Liu, D.
Wang, Y.
Wang, G.
Powiązania:
https://bibliotekanauki.pl/articles/174466.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
uniaxial crystal
anomalous hollow vortex beam
laser propagation
Opis:
The analytical equation of an anomalous hollow vortex beam propagating in a uniaxial crystal orthogonal to the optical axis is derived, and the intensity and phase properties of this beam propagating in the uniaxial crystal are illustrated using numerical examples. The influences of topological charge M and the ratio of refractive index ne/no of a uniaxial crystal on the normalized intensity distribution and phase distribution for anomalous hollow vortex beam are discussed and analyzed in detail.
Źródło:
Optica Applicata; 2018, 48, 1; 95-104
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The optimization of the dielectric layer photonic crystal filter by the quadratic response surface methodology
Autorzy:
Yang, H.
Meng, S
Wang, G.
Huang, C.
Powiązania:
https://bibliotekanauki.pl/articles/174592.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
optimization
photonic crystal filter
response surface methodology
Opis:
Dielectric layer photonic crystal filter structures in waveguide are optimized by the quadratic response surface methodology. The optimization model of the filter is established on the basis of the analysis which is conducted with the aid of the response surface methodology. The model is solved using sequential quadratic programming and the optimal parameters are obtained. Examples demonstrate it is effective.
Źródło:
Optica Applicata; 2015, 45, 3; 369-379
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Disparity servoing based fast autofocusing method for stereomicroscope
Autorzy:
Liu, Y.
Yu, M.
Cui, L.
Jiang, G.
Wang, G.
Fan, S.
Powiązania:
https://bibliotekanauki.pl/articles/174449.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
autofocusing
stereomicroscope
stereomicroscopic images
disparity
Opis:
A disparity servoing based fast autofocusing method is proposed for stereomicroscopes according to linear relationship between the disparity change in stereomicroscopic images and the move distance of a motorized translation stage. For a certain stereomicroscope, the calibration of a disparity range of clear images at each magnification is implemented offline. After that, the disparity of the stereomicroscopic image is used as an index to represent the sharpness of an arbitrary image. If the disparity does not satisfy the requirement, move steps and direction of a step motor are calculated by utilizing the linear relationship between the disparity change and the move distance of the stage. The iteration will be continued until the disparity of the captured stereomicroscopic image approximates to the clearest disparity. The experimental results show that the proposed method only requires a few iterations and less time to reach the focus position, and the disparity error is less than 0.5 pixel.
Źródło:
Optica Applicata; 2016, 46, 4; 651-663
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on self-repairing and non-diffraction of Airy beams in slant atmospheric turbulence
Autorzy:
Li, Y.-Q.
Wang, L.-G.
Powiązania:
https://bibliotekanauki.pl/articles/174867.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
atmospheric turbulence
Airy beam
self-repairing
non-diffraction
numerical simulation
Opis:
The Airy beams propagation in atmospheric turbulence along a slant path was simulated numerically, based on the split-step Fourier method. Also, the self-repairing and non-diffraction characteristics of Airy beams were investigated and compared with beams propagation on a horizontal path. The effects of parameters including zenith angle, propagation distance, radii of Gaussian aperture and turbulence intensity on the two characteristics of beams were revealed. Additionally, the two characteristics of the Airy beam were compared with those of a Bessel–Gauss beam. The results showed that the two beams obscured by Gaussian apertures can be repaired after propagating some distance along a slant path. However, the non-diffraction characteristic of an Airy beam was stronger than that of a Bessel–Gauss beam and the amplitude attenuation rate of the Bessel–Gauss beam was greater than that of the Airy beam in the process of self-repairing. Results obtained can provide a theoretical basis for an outdoor experiment as well as theoretical guidance for various practical applications including laser communications, laser warning systems, and remote sensing.
Źródło:
Optica Applicata; 2018, 48, 3; 435-447
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monte Carlo based angular analysis of multiple scattered photons for underwater optical imaging
Autorzy:
Li, S.
Wang, R.
Chen, G.
Powiązania:
https://bibliotekanauki.pl/articles/173322.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
underwater imaging
turbid media
Monte Carlo method
multiple scattering
Opis:
Image contrast and visibility associated with underwater optical imaging systems are usually degraded by the absorbing and scattering effects of turbid waters. To improve the image contrast, laser-range-gate has been widely applied to underwater optical imaging systems. The work of Katsev et al. (Appl.Opt. 38(33), 1999, pp. 6849–6858) shows that the contrast of a shadow image is greater than that of the object image. The present paper outlines a Monte Carlo based simulation method of image formation for underwater optical imaging. It is found that the contrast of a shadow image varies with gate starting depths. The angular distribution of multiply scattered photons is obtained via semi-analytical models (Shengfu Li et al., Opt.Commun. 381, 2016, pp. 43–47). The simulated results show that increasing the gate starting depth can reduce the highly backscattered photons, thus can improve the image contrast.
Źródło:
Optica Applicata; 2018, 48, 2; 237-247
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Moving-aperture-based three-dimensional micro-measurement system
Autorzy:
Fan, S.
Yu, M.
Jiang, G.
Wang, Y.
Wang, W.
Li, W.
Powiązania:
https://bibliotekanauki.pl/articles/174026.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
optical microscopy
computational photography
three-dimensional micro-measurement
moving aperture
Opis:
To overcome the depth-of-field limitation of an optical microscope image, a three-dimensional measurement method with a superior depth-of-field is proposed. In the proposed method, light-field information of different angles is obtained by moving the aperture and the three-dimensional scene is reconstructed by using a computational reconstruction technology. First, stereo matching of different aperture position images is performed to obtain the multi-aperture imaging deviation. The focal plane moving distance is thereby estimated. Then, the relational expression between the image coordinates and the focal plane moving distance is determined according to the image coordinates. Two dimensional coordinates of the space point are obtained by the expression coefficients. Finally, the depth coordinates are computed, and three-dimensional reconstruction of the spatial points is completed. Experiments of three-dimensional measurements of the calibration board with different angles and circuit boards are conducted. The results show that the maximum error of the distance measurement is controlled into 0.84%, and the maximum angle measurement error is controlled into 4.56%.
Źródło:
Optica Applicata; 2018, 48, 4; 533-547
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A simple model of the scanning near-field optical microscopy probe tip for electric field enhancement
Autorzy:
Wang, Y.
Cai, W.
Yang, M.
Liu, Z.
Shang, G.
Powiązania:
https://bibliotekanauki.pl/articles/174091.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
near-field tip
electromagnetic field enhancement
finite-difference time-domain
FDTD
Opis:
In this paper, we present a simple near-field probe model that is composed of an elongated ellipsoid and a finite metal truncated cone. The elongated ellipsoid has been shown to act as a protrusion or separate particle near a truncated cone apex with strong near-field enhancement under laser excitation. By controllably varying the length of the ellipsoid protrusion from the truncated cone, the truncated cone-ellipsoid probes can be adapted to the suitability of near-field probes. The effects of substrate material and excitation wavelength on the near field enhancement for different tip apexes are also discussed. In addition, we compared the properties of the truncated cone-ellipsoid probe with the widely used hemisphere conical tip by launching surface plasmon polaritons on plasmonic waveguides to prove the suitability of the truncated cone-ellipsoid probes as high performance near-field probes. The present simple model would provide a theoretical basis for the actual construction of probes.
Źródło:
Optica Applicata; 2017, 47, 1; 119-130
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A method for measuring the quality parameters of image intensifier based on projecting phase-shifting gratings
Autorzy:
Sun, S.
Cao, Y.
Chen, C.
Fu, G.
Wang, Y.
Xu, X.
Powiązania:
https://bibliotekanauki.pl/articles/174300.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
phase measurement
phase-shifting grating
distortion
image intensifier
imaging quality parameter
Opis:
A method for measuring the quality parameters of image intensifier based on projecting phase-shifting gratings is proposed. A set of designed phase-shifting gratings are projected into the measuring system orderly to obtain the magnification parameter of the measured image intensifier, and the phase caused by the measured image intensifier. After obtaining the referential phase caused by only the magnification of the measured image intensifier, the phase caused by the distortion of the measured image intensifier is extracted by phase calculating and phase unwrapping. Both the global distortion and the partial distortion of the measured image intensifier can be measured by phase-to-distortion matching at the same time. The experimental results show that the proposed method can measure the multiple quality parameters of image intensifier effectively.
Źródło:
Optica Applicata; 2018, 48, 1; 39-51
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A super depth of field height measurement based on local disparity
Autorzy:
Cui, L.
Liu, Y.
Yu, M.
Jiang, G.
Fan, S.
Wang, Y.
Powiązania:
https://bibliotekanauki.pl/articles/173522.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
microscopes
binocular vision
local disparity map
depth of field (DOF)
height measurement
Opis:
A super depth of field height measurement method is proposed to measure the object height with the optical stereoscopic microscope. The quasi-Euclidean epipolar rectification algorithm is utilized on the original stereoimage to obtain rectified stereoimages and calibrate two camera parameters. Then, feature points are obtained by the SURF (speed up robust feature) algorithm and their corresponding disparities are calculated. The disparity-depth of field curve is fitted by combining the step height values of a stepper motor. Moreover, through local disparity value got from feature points on the object, the relative shift height is calculated through regression analysis. Finally, according to binocular vision geometry, the thickness of the object can be calculated. Experimental results show that the measurement error in Z direction is from 1.51% to 7.71%, which indicates that the proposed method is able to measure the height of a microobject beyond depth of field within a tolerant error.
Źródło:
Optica Applicata; 2015, 45, 2; 205-214
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improved method for phase wraps reduction in profilometry
Autorzy:
Du, G.
Wang, M.
Zhou, C.
Si, S.
Li, H.
Lei, Z.
Li, Y.
Powiązania:
https://bibliotekanauki.pl/articles/173793.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
phase unwrapping
zero-padding
Fourier transform
carrier-frequency
profilometry
Opis:
In order to completely eliminate, or greatly reduce the number of phase wraps in 2D wrapped phase map, Gdeisat and co-workers proposed an algorithm, which uses shifting the spectrum towards the origin. But the spectrum can be shifted only by an integer number, meaning that the phase wraps reduction is often not optimal. In addition, Gdeisat’s method will take much time to make the Fourier transform, inverse Fourier transform, select and shift the spectral components. In view of the above problems, we proposed an improved method for phase wraps elimination or reduction. First, the wrapped phase map is padded with zeros, the carrier frequency of the projected fringe is determined by high resolution, which can be used as the moving distance of the spectrum. And then realize frequency shift in spatial domain. So it not only can enable the spectrum to be shifted by a rational number when the carrier frequency is not an integer number, but also reduce the execution time. Finally, the experimental results demonstrated that the proposed method is feasible.
Źródło:
Optica Applicata; 2017, 47, 2; 295-306
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical investigation of vanadium oxide film with surface microstructure
Autorzy:
Hong, W.
Wang, Z.
Chen, Q.
Sheng, C.
Gu, G.
Luo, P.
Xie, Y.
Powiązania:
https://bibliotekanauki.pl/articles/174416.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
vanadium oxide
VO2
film
surface microstructure
photonic band edge
dispersion material
Opis:
This paper presents a method to design a surface microstructure of vanadium oxide to enhance optical absorption. This method, using a density of eigenfrequency, can be calculated by a planar wave expand method, to indicate the absorption efficiency of a dispersion material, which can be used as an approach method for further design. Based on this, a nanostructure-based vanadium oxide film is designed and simulated to validate this method. The simulation results show that the tendency of density of eigenfrequency is corresponding to the tendency of optical absorption enhancement. Moreover, this structure can achieve high optical broadband absorption when the material dispersion is considered. High optical absorption enhancement can be achieved by adjusting the geometrical parameters; our maximum overall enhancement absorption ratio was 31.84% at the metal phase, which can be attributed to the enhancement effect of a photonic band edge.
Źródło:
Optica Applicata; 2017, 47, 4; 601-609
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
One shot profilometry using iterative two-step temporal phase-unwrapping
Autorzy:
Du, G.
Wang, M.
Zhou, C.
Si, S.
Li, H.
Lei, Z.
Li, Y.
Powiązania:
https://bibliotekanauki.pl/articles/173912.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
phase unwrapping
composite fringe pattern
Fourier transform
two-step temporal phase-unwrapping
Opis:
This paper reviews two techniques that have been recently published for three-dimensional profilometry and proposes one shot profilometry using iterative two-step temporal phase-unwrapping by combining the composite fringe projection and the iterative two-step temporal phase unwrapping algorithm. In temporal phase unwrapping, many images with different frequency fringe pattern are needed to project, which would take much time. In order to solve this problem, Ochoa proposed a phase unwrapping algorithm based on phase partitions using a composite fringe. However, we found that the fringe order determined through the construction of phase partitions tended to be imprecise. Recently, we proposed an iterative two-step temporal phase unwrapping algorithm, which can achieve high sensitivity and high precision shape measurement. But it needs multiple frames of fringe images which would take much time. In order to take into account both the speed and accuracy of three-dimensional shape measurement, we get a new, and more accurate unwrapping method based on a composite fringe pattern by combining these two techniques. This method not only retains the speed advantage of Ochoa’s algorithm, but also greatly improves its measurement accuracy. Finally, the experimental evaluation is conducted to prove the validity of the proposed method.
Źródło:
Optica Applicata; 2017, 47, 1; 97-110
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Room-temperature sensing performance of hydrogen using palladium-based film by optical setup
Autorzy:
Yao, Yiyun
Corso, Alain J.
Bazzan, Marco
Tessarolo, Enrico
Wang, Zhanshan
Huang, Qiushi
Qi, Runze
Martucci, A.
Pelizzo, Maria G.
Powiązania:
https://bibliotekanauki.pl/articles/1835811.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
hydrogen detection
palladium-based film
palladium–platinum alloy film
optical sensor
Opis:
H2 sensing performance of novel Pd–Pt alloy films has been compared with those obtained by using Pd films and H2-reducted PdO films. Two different detecting systems were used to measure the hydrogenation and de-hydrogenation phases with a H2 concentration of both 5% v/v nitrogen and 1% v/v nitrogen at room temperature. The sensitivity loss observed for the Pd–Pt alloy and H2-reducted PdO samples with respect to pure Pd samples can be explained in terms of the reduction in the lattice constant and interstitial volume due to the Pt addition, which determine a decrement of hydrogen atoms penetrating in the films. On the other hand, results show an improvement in time-response for Pd–Pt alloy and H2-reducted PdO films with respect to pure Pd ones, presumably due to the increase of its permeability to H2. Moreover, the sensing measurements repeated after 60 days show that the Pd–Pt alloy films, unlike the Pd-based ones, fully preserve their performances, demonstrating the advantage of the Pt inclusion for stability purposes when the samples are stored upon humidity.
Źródło:
Optica Applicata; 2020, 50, 4; 649-661
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mitigation scratch on fused silica optics using CO2 laser
Autorzy:
Liu, C.-M.
Yan, Z.-H.
Yang, L.
Jiang, Y.
Zu, X.-T.
Wang, H.-J.
Liao, W.
Yuan, X.-D.
Zheng, W.-G.
Powiązania:
https://bibliotekanauki.pl/articles/174978.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
mitigation
scratch
fused silica
CO2 laser
Opis:
The scratch on a fused silica surface was treated as a chain of connected damage sites and mitigated one after another using CO2 laser irradiation. The optical microscopy image shows that a scratch with the width of about 30 μm and length of several millimeters can be completely mitigated without the formation of debris and bubbles. The mitigated scratch can survive under raster scan laser irradiation with the fluency increased up to 11.0J/cm2 at 3ns and 351nm. On the contrary, the substrate without CO2 laser mitigation is seriously damaged under this irradiation. The light modulation induced by mitigation is much smaller when the scratch is mitigated before being damaged. The light modulation is about 2 when the distance to the mitigated sample is larger than 20cm. The birefringence induced by residual stress in the mitigated scratch is measured. The retardance of the mitigated scratch before being damaged is not visible. Therefore, residual stress in this mitigated scratch before being damaged should be not a critical potential risk in laser damage.
Źródło:
Optica Applicata; 2016, 46, 3; 387-397
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-14 z 14

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