The Experts below are selected from a list of 10467 Experts worldwide ranked by ideXlab platform
Hui Zhao - One of the best experts on this subject based on the ideXlab platform.
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Analytical and experimental demonstration of depth of field extension for incoherent imaging system with a standard sinusoidal Phase Mask
Chinese Optics Letters, 2012Co-Authors: Hui Zhao, Yingcai LiAbstract:The wavefront coding technique is used to enlarge the depth of field (DOF) of incoherent imaging systems.The key to wavefront coding lies in the design of suitable Phase Masks. To date, numerous kinds of Phase Masks are proposed. However, further understanding is needed regarding Phase Mask with its Phase function being in a standard sinusoidal form. Therefore, the characteristics of such a Phase Mask are studied in this letter. Deriving the defocused optical transfer function (OTF) analytically proves that the standard sinusoidal Phase Mask is effective in extending the DOF, and actual experiments confirm the numerical results. At the same time, with the Fisher information as a criterion, the standard sinusoidal Phase Mask shows a higher tolerance to focus errors (especially severe focus errors) than the classical cubic Phase Mask.
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optimized sinusoidal Phase Mask to extend the depth of field of an incoherent imaging system
Optics Letters, 2010Co-Authors: Hui Zhao, Yingcai LiAbstract:Wavefront coding is a powerful technique that can be used to extend the depth of field of an incoherent imaging system. By adding a suitable Phase Mask to the aperture plane, the optical transfer function of a conventional imaging system can be made defocus invariant. Since 1995, when a cubic Phase Mask was first suggested, many kinds of Phase Masks have been proposed to achieve the goal of depth extension. In this Letter, a Phase Mask based on sinusoidal function is designed to enrich the family of Phase Masks. Numerical evaluation demonstrates that the proposed Mask is not only less sensitive to focus errors than cubic, exponential, and modified logarithmic Masks are, but it also has a smaller point-spread-function shifting effect.
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performance of an improved logarithmic Phase Mask with optimized parameters in a wavefront coding system
Applied Optics, 2010Co-Authors: Hui Zhao, Yingcai LiAbstract:In two papers [Proc. SPIE4471, 272-280 (2001)PSISDG0277-786X10.1117/12.449345 and Appl. Opt.43, 2709-2721 (2004)APOPAI0003-693510.1364/AO.43.002709], a logarithmic Phase Mask was proposed and proved to be effective in extending the depth of field; however, according to our research, this Mask is not that perfect because the corresponding defocused modulation transfer function has large oscillations in the low-frequency region, even when the Mask is optimized. So, in a previously published paper [Opt. Lett.33, 1171-1173 (2008)OPLEDP0146-959210.1364/OL.33.001171], we proposed an improved logarithmic Phase Mask by making a small modification. The new Mask can not only eliminate the drawbacks to a certain extent but can also be even less sensitive to focus errors according to Fisher information criteria. However, the performance comparison was carried out with the modified Mask not being optimized, which was not reasonable. In this manuscript, we optimize the modified logarithmic Phase Mask first before analyzing its performance and more convincing results have been obtained based on the analysis of several frequently used metrics.
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improved logarithmic Phase Mask to extend the depth of field of an incoherent imaging system
Optics Letters, 2008Co-Authors: Hui Zhao, Qi Li, Huajun FengAbstract:A logarithmic Phase Mask was proposed in 2001, and the depth extension effect was proved at the same time. Three years later, in 2004, further research on that kind of Mask obtained more results. This valuable work can be found in two papers [Proc. SPIE 4471, 272 (2001) and Appl. Opt. 43, 2709 (2004)]. We reviewed the papers carefully and made simple modifications to that Mask. The modified Phase Mask still had the logarithmic form, but the simulation results demonstrated that it was superior to the original one.
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Research on design of optimum Phase Mask for wave-front coded imaging system
Optical Design and Testing III, 2007Co-Authors: Hui Zhao, Huajun Feng, Qi LiAbstract:Wave-front coding is a system level design method which can be used to extend the depth of field of an incoherent optical system. By attaching a Phase Mask to the aperture, the optical transfer function can not only be made insensitive to misfocus, but also can avoid the isolated zeros caused by defocus. With this modified optical transfer function, a purposely blurred image can be obtained and its corresponding clear one with large depth of focus can be generated through digital processing techniques, such as direct inverse filtering, wiener filtering and maximum entropy restoration and so on. This is why the wave-front coded imaging system is called optical/digital hybrid imaging system as well. The most important part of the system design lies in the design of Phase Masks. So far, many kinds of Phase Masks have been suggested; among all those types, two are classical: cubic-Phase-Mask and logarithmic-Phase-Mask. However, whether an optimum Phase Mask exists or not is still a question that is not answered yet. This paper focuses on this question and tries to find one answer. In this paper, considering several critical factors and with the help of a simulation program developed by ourselves, we make a comparison among the performance of different Phase Masks and finally propose a prototype Phase Mask whose performance is acceptable in several aspects.
Yingcai Li - One of the best experts on this subject based on the ideXlab platform.
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Analytical and experimental demonstration of depth of field extension for incoherent imaging system with a standard sinusoidal Phase Mask
Chinese Optics Letters, 2012Co-Authors: Hui Zhao, Yingcai LiAbstract:The wavefront coding technique is used to enlarge the depth of field (DOF) of incoherent imaging systems.The key to wavefront coding lies in the design of suitable Phase Masks. To date, numerous kinds of Phase Masks are proposed. However, further understanding is needed regarding Phase Mask with its Phase function being in a standard sinusoidal form. Therefore, the characteristics of such a Phase Mask are studied in this letter. Deriving the defocused optical transfer function (OTF) analytically proves that the standard sinusoidal Phase Mask is effective in extending the DOF, and actual experiments confirm the numerical results. At the same time, with the Fisher information as a criterion, the standard sinusoidal Phase Mask shows a higher tolerance to focus errors (especially severe focus errors) than the classical cubic Phase Mask.
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optimized sinusoidal Phase Mask to extend the depth of field of an incoherent imaging system
Optics Letters, 2010Co-Authors: Hui Zhao, Yingcai LiAbstract:Wavefront coding is a powerful technique that can be used to extend the depth of field of an incoherent imaging system. By adding a suitable Phase Mask to the aperture plane, the optical transfer function of a conventional imaging system can be made defocus invariant. Since 1995, when a cubic Phase Mask was first suggested, many kinds of Phase Masks have been proposed to achieve the goal of depth extension. In this Letter, a Phase Mask based on sinusoidal function is designed to enrich the family of Phase Masks. Numerical evaluation demonstrates that the proposed Mask is not only less sensitive to focus errors than cubic, exponential, and modified logarithmic Masks are, but it also has a smaller point-spread-function shifting effect.
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performance of an improved logarithmic Phase Mask with optimized parameters in a wavefront coding system
Applied Optics, 2010Co-Authors: Hui Zhao, Yingcai LiAbstract:In two papers [Proc. SPIE4471, 272-280 (2001)PSISDG0277-786X10.1117/12.449345 and Appl. Opt.43, 2709-2721 (2004)APOPAI0003-693510.1364/AO.43.002709], a logarithmic Phase Mask was proposed and proved to be effective in extending the depth of field; however, according to our research, this Mask is not that perfect because the corresponding defocused modulation transfer function has large oscillations in the low-frequency region, even when the Mask is optimized. So, in a previously published paper [Opt. Lett.33, 1171-1173 (2008)OPLEDP0146-959210.1364/OL.33.001171], we proposed an improved logarithmic Phase Mask by making a small modification. The new Mask can not only eliminate the drawbacks to a certain extent but can also be even less sensitive to focus errors according to Fisher information criteria. However, the performance comparison was carried out with the modified Mask not being optimized, which was not reasonable. In this manuscript, we optimize the modified logarithmic Phase Mask first before analyzing its performance and more convincing results have been obtained based on the analysis of several frequently used metrics.
Paul R Prucnal - One of the best experts on this subject based on the ideXlab platform.
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temporal Phase Mask encrypted optical steganography carried by amplified spontaneous emission noise
Optics Express, 2014Co-Authors: Ben Wu, Zhenxing Wang, Bhavin J Shastri, Matthew P Chang, Nicholas A Frost, Paul R PrucnalAbstract:A temporal Phase Mask encryption method is proposed and experimentally demonstrated to improve the security of the stealth channel in an optical steganography system. The stealth channel is protected in two levels. In the first level, the data is carried by amplified spontaneous emission (ASE) noise, which cannot be detected in either the time domain or spectral domain. In the second level, even if the eavesdropper suspects the existence of the stealth channel, each data bit is covered by a fast changing Phase Mask. The Phase Mask code is always combined with the wide band noise from ASE. Without knowing the right Phase Mask code to recover the stealth data, the eavesdropper can only receive the noise like signal with randomized Phase.
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Phase-Mask covered optical steganography based on amplified spontaneous emission noise
2013 IEEE Photonics Conference, 2013Co-Authors: Ben Wu, Zhenxing Wang, Bhavin J Shastri, Yue Tian, Paul R PrucnalAbstract:Phase Mask encryption is proposed to improve the transmission privacy of an optical steganography system. The stealth signal carried by amplified spontaneous emission noise is encrypted by a fast changing code.
M. Reid - One of the best experts on this subject based on the ideXlab platform.
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Improving optical-to-THz conversion efficiency using a binary Phase Mask
Nonlinear Optics, 2011Co-Authors: Xavier Ropagnol, Roberto Morandotti, Tsuneyuki Ozaki, M. ReidAbstract:We demonstrate efficient generation of quasi-single-cycle THz pulses using an interdigitated GaAs Large Area Photoconductive Antenna LAPCA with a binary Phase Mask. The binary Phase Mask results in a time-delayed excitation of the GaAs antenna, which allows subsequent antennas to produce an additive field. The resulting of this additive field is the generation of a quasi single cycle Thz pulse. We demonstrate control over the temporal profile of the THz waveform to maximize optical-to-THz conversion efficiency, and investigate temporal shaping of the THz field using different Phase Masks.
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thz pulse shaping and improved optical to thz conversion efficiency using a binary Phase Mask
Optics Letters, 2011Co-Authors: Xavier Ropagnol, Roberto Morandotti, Tsuneyuki Ozaki, M. ReidAbstract:We demonstrate improved optical-to-terahertz (THz) conversion efficiency and THz pulse shaping from an interdigitated GaAs large area photoconductive antenna by using a binary Phase Mask. The binary Phase Mask results in a time-delayed excitation of the adjacent antennas, which allows subsequent antennas to produce an additive field, thus resulting in a quasi-single-cycle THz pulse. We demonstrate control over the temporal profile of the THz waveform to maximize optical-to-THz conversion efficiency.
Shinichi Komatsu - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of inverse tangent Phase Mask in wavefront coding
2017 22nd Microoptics Conference (MOC), 2017Co-Authors: Masaya Takahashi, Shinichi KomatsuAbstract:An inverse tangential Phase Mask (ITPM) is potentially effective for extending the depth of field in the wavefront coding method. However, its characteristics have not been reported in detail. In this study, we obtained the ITPM profile function and confirmed that the optimized ITPM is more effective than a cubic Phase Mask (CPM) in several respects.
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optimized free form Phase Mask for extension of depth of field in wavefront coded imaging
Optics Letters, 2008Co-Authors: Yasuhisa Takahashi, Shinichi KomatsuAbstract:To achieve a further extension of the depth of field in wavefront-coded imaging by reducing the impact of focus error in the optical transfer function, we propose the use of a free-form Phase Mask (FPM) instead of a conventional cubic Phase Mask (CPM). We optimized the shape of the FPM using the simulated annealing algorithm and confirmed that the optimized FPM provides a much larger focal tolerance and better final images than the CPM in the noise-free case.
