As a typical technology for optical encryption,phase retrieval algorithms have been widely used in optical information encryption and authentication systems.This paper presents three applications of two-dimensional(2D...As a typical technology for optical encryption,phase retrieval algorithms have been widely used in optical information encryption and authentication systems.This paper presents three applications of two-dimensional(2D)phase retrieval for optical encryption and authentication:first,a hierarchical image encryption system,by which multiple images can be hidden into cascaded multiple phase masks;second,a multilevel image authentication system,which combines(t,n)threshold secret sharing(both t and n are positive integers,and t≤n)and phase retrieval,and provides both high-level and low-level authentication;and finally,a hierarchical multilevel authentication system that combines the secret sharing scheme based on basic vector operations and the phase retrieval,by which more certification images can be encoded into multiple cascaded phase masks of different hierarchical levels.These three phase retrieval algorithms can effectively illustrate phase-retrievalbased optical information security.The principles and features of each phase-retrieval-based optical security method are analyzed and discussed.It is hoped that this review will illustrate the current development of phase retrieval algorithms for optical information security and will also shed light on the future development of phase retrieval algorithms for optical information security.展开更多
Coherent diffractive imaging （CDI） is a lensless imaging technique and can achieve a resolution beyond the Rayleigh or Abbe limit. The ptychographical iterative engine （PIE） is a CDI phase retrieval algorithm that...Coherent diffractive imaging （CDI） is a lensless imaging technique and can achieve a resolution beyond the Rayleigh or Abbe limit. The ptychographical iterative engine （PIE） is a CDI phase retrieval algorithm that uses multiple diffraction patterns obtained through the scan of a localized illumination on the specimen, which has been demonstrated successfully at optical and X-ray wavelengths. In this paper, a general PIE algorithm （gPIE） is presented and demonstrated with an He-Ne laser light diffraction dataset. This algorithm not only permits the removal of the accurate model of the illumination function in PIE, but also provides improved convergence speed and retrieval quality.展开更多
This paper provides a contemporary overview of phase retrieval problem with PhaseLift algorithm and summarizes theoretical results which have been derived during the past few years.Based on the lifting technique,the p...This paper provides a contemporary overview of phase retrieval problem with PhaseLift algorithm and summarizes theoretical results which have been derived during the past few years.Based on the lifting technique,the phase retrieval problem can be transformed into the low rank matrix recovery problem and then be solved by convex programming known as PhaseLift.Thus,stable guarantees for such problem have been gradually established for measurements sampled from sufficiently random distribution,for instance,the standard normal distribution.Further,exact recovery results have also been set up for masked Fourier measurements which are closely related to practical applications.展开更多
A convolutional neural network is employed to retrieve the time-domain envelop and phase of few-cycle femtosecond pulses from transient-grating frequency-resolved optical gating(TG-FROG) traces.We use theoretically ge...A convolutional neural network is employed to retrieve the time-domain envelop and phase of few-cycle femtosecond pulses from transient-grating frequency-resolved optical gating(TG-FROG) traces.We use theoretically generated TGFROG traces to complete supervised trainings of the convolutional neural networks,then use similarly generated traces not included in the training dataset to test how well the networks are trained.Accurate retrieval of such traces by the neural network is realized.In our case,we find that networks with exponential linear unit(ELU) activation function perform better than those with leaky rectified linear unit(LRELU) and scaled exponential linear unit(SELU).Finally,the issues that need to be addressed for the retrieval of experimental data by this method are discussed.展开更多
Focusing light though scattering media beyond the ballistic regime is a challenging task in biomedical optical imaging.This challenge can be overcome by wavefront shaping technique,in which a time reversed(TR)wavefron...Focusing light though scattering media beyond the ballistic regime is a challenging task in biomedical optical imaging.This challenge can be overcome by wavefront shaping technique,in which a time reversed(TR)wavefront of scattered light is generated to suppress the scattering.In previous TR optical focusing experiments,a phase only spatial light modulator(SLM)has.been typically used to control the wavefront of incident light.Unfortunately,although the phase information is reconstructed by the phase-only SLM,the amplitude information is lost,resulting in decreased peak to-background ratio(PBR)of optical focusing in the TR wavefront recon-struction.A new method of TR optical focusing through scattering media is proposed here,which numerically reonstructs the full phase and amplitude of a simulated scattered light field by using a single phase only SLM.Simulation results and the proposed optical setup show that the time-reversal of a fully developed speckle field can be digially implemented with both phase and ampltude recovery,affording a way to improve the performance of light focusing through scattering media.展开更多
The technology for phase detection of liquid crystal optical device is a difficult research in current domestic and overseas. However, for the existing liquid crystal optical device, aiming at the poor anti-vibration ...The technology for phase detection of liquid crystal optical device is a difficult research in current domestic and overseas. However, for the existing liquid crystal optical device, aiming at the poor anti-vibration capability and poor versatile of phase detection, the complexity of phase retrieval algorithm, we propose a new phase measurement principle and experimental methods of liquid crystal optical device. It is a phase measurement method based on the combination of phase- shifting interferometer and phase conjugation technology. The deflection characteristics of the liquid crystal device means the device can implement phase modulation to only one direction of polarized light while is completely transparent to orthogonal polarized light. We put forward the phase shift of the orthogonal polarization phase shift interferometer method, using phase shifting interference as well as the combination of phase conjugate means to achieve its phase measurement. So we can retrieves devices modulation phase simply and efficiently combines with phase- shifting interferometer technology.展开更多
Phase contrast imaging technique has been improved promptly in recent years. Among these techniques in-line phase-contrast imaging is widely used. Various algorithms for in-line phase retrieval have been proposed so f...Phase contrast imaging technique has been improved promptly in recent years. Among these techniques in-line phase-contrast imaging is widely used. Various algorithms for in-line phase retrieval have been proposed so far such as TIE(transport of intensity equation), CTF(contrast transfer function), first born-approximations, GSF(Gerchberg-Saxton-Fienup), etc. Bronnikov's algorithm(BA) is a type of linear algorithm that is simple and efficient. But it can only be used without absorption situations. In this paper, an improved algorithm based on BA was presented. The approach adds Δφ(x,y) to the phase map φ_b(x,y) retrieved by BA to make the reconstructed phase map more precise. Further, the approach was evaluated on simulated images and confirmed to be accurate at higher absorption rates.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61775121,61605165,61307003,61405122,and 11574311)the Key Research and Development Program of Shandong Province,China(Grant No.2018GGX101002)+1 种基金the Natural Science Foundation of Shandong Province,China(Grant No.ZR2019QF006)the Fundamental Research Funds of Shandong University,China(Grant No.2015GN031)
文摘As a typical technology for optical encryption,phase retrieval algorithms have been widely used in optical information encryption and authentication systems.This paper presents three applications of two-dimensional(2D)phase retrieval for optical encryption and authentication:first,a hierarchical image encryption system,by which multiple images can be hidden into cascaded multiple phase masks;second,a multilevel image authentication system,which combines(t,n)threshold secret sharing(both t and n are positive integers,and t≤n)and phase retrieval,and provides both high-level and low-level authentication;and finally,a hierarchical multilevel authentication system that combines the secret sharing scheme based on basic vector operations and the phase retrieval,by which more certification images can be encoded into multiple cascaded phase masks of different hierarchical levels.These three phase retrieval algorithms can effectively illustrate phase-retrievalbased optical information security.The principles and features of each phase-retrieval-based optical security method are analyzed and discussed.It is hoped that this review will illustrate the current development of phase retrieval algorithms for optical information security and will also shed light on the future development of phase retrieval algorithms for optical information security.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11179009 and 50875013)the Beijing Municipal Natural Science Foundation, China (Grant No. 4102036)the Beijing NOVA Program, China (Grant No. 2009A09)
文摘Coherent diffractive imaging （CDI） is a lensless imaging technique and can achieve a resolution beyond the Rayleigh or Abbe limit. The ptychographical iterative engine （PIE） is a CDI phase retrieval algorithm that uses multiple diffraction patterns obtained through the scan of a localized illumination on the specimen, which has been demonstrated successfully at optical and X-ray wavelengths. In this paper, a general PIE algorithm （gPIE） is presented and demonstrated with an He-Ne laser light diffraction dataset. This algorithm not only permits the removal of the accurate model of the illumination function in PIE, but also provides improved convergence speed and retrieval quality.
基金Supported by the National Natural Science Foundation of China(11531013,U1630116)the fundamental research funds for the central universities.
文摘This paper provides a contemporary overview of phase retrieval problem with PhaseLift algorithm and summarizes theoretical results which have been derived during the past few years.Based on the lifting technique,the phase retrieval problem can be transformed into the low rank matrix recovery problem and then be solved by convex programming known as PhaseLift.Thus,stable guarantees for such problem have been gradually established for measurements sampled from sufficiently random distribution,for instance,the standard normal distribution.Further,exact recovery results have also been set up for masked Fourier measurements which are closely related to practical applications.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFB0405202)the National Natural Science Foundation of China(Grant Nos.61690221,91850209,and 11774277)。
文摘A convolutional neural network is employed to retrieve the time-domain envelop and phase of few-cycle femtosecond pulses from transient-grating frequency-resolved optical gating(TG-FROG) traces.We use theoretically generated TGFROG traces to complete supervised trainings of the convolutional neural networks,then use similarly generated traces not included in the training dataset to test how well the networks are trained.Accurate retrieval of such traces by the neural network is realized.In our case,we find that networks with exponential linear unit(ELU) activation function perform better than those with leaky rectified linear unit(LRELU) and scaled exponential linear unit(SELU).Finally,the issues that need to be addressed for the retrieval of experimental data by this method are discussed.
基金supported by the National Science Foundation of China (61177018)the Program for New Century Excellent Talents in University (NECT-11-0596)Beijing Nova Program (2011066).
文摘Focusing light though scattering media beyond the ballistic regime is a challenging task in biomedical optical imaging.This challenge can be overcome by wavefront shaping technique,in which a time reversed(TR)wavefront of scattered light is generated to suppress the scattering.In previous TR optical focusing experiments,a phase only spatial light modulator(SLM)has.been typically used to control the wavefront of incident light.Unfortunately,although the phase information is reconstructed by the phase-only SLM,the amplitude information is lost,resulting in decreased peak to-background ratio(PBR)of optical focusing in the TR wavefront recon-struction.A new method of TR optical focusing through scattering media is proposed here,which numerically reonstructs the full phase and amplitude of a simulated scattered light field by using a single phase only SLM.Simulation results and the proposed optical setup show that the time-reversal of a fully developed speckle field can be digially implemented with both phase and ampltude recovery,affording a way to improve the performance of light focusing through scattering media.
文摘The technology for phase detection of liquid crystal optical device is a difficult research in current domestic and overseas. However, for the existing liquid crystal optical device, aiming at the poor anti-vibration capability and poor versatile of phase detection, the complexity of phase retrieval algorithm, we propose a new phase measurement principle and experimental methods of liquid crystal optical device. It is a phase measurement method based on the combination of phase- shifting interferometer and phase conjugation technology. The deflection characteristics of the liquid crystal device means the device can implement phase modulation to only one direction of polarized light while is completely transparent to orthogonal polarized light. We put forward the phase shift of the orthogonal polarization phase shift interferometer method, using phase shifting interference as well as the combination of phase conjugate means to achieve its phase measurement. So we can retrieves devices modulation phase simply and efficiently combines with phase- shifting interferometer technology.
基金Shanghai Synchrotron Radiation Facility(SSRF)National Natural Science Foundation of China+4 种基金grant number:NSFC11005074 and NSFC50725622Doctoral Fund of Ministry of Education of Chinagrant number:20100073120004National Basic Research Program of Chinagrant number:2010CB834300
文摘Phase contrast imaging technique has been improved promptly in recent years. Among these techniques in-line phase-contrast imaging is widely used. Various algorithms for in-line phase retrieval have been proposed so far such as TIE(transport of intensity equation), CTF(contrast transfer function), first born-approximations, GSF(Gerchberg-Saxton-Fienup), etc. Bronnikov's algorithm(BA) is a type of linear algorithm that is simple and efficient. But it can only be used without absorption situations. In this paper, an improved algorithm based on BA was presented. The approach adds Δφ(x,y) to the phase map φ_b(x,y) retrieved by BA to make the reconstructed phase map more precise. Further, the approach was evaluated on simulated images and confirmed to be accurate at higher absorption rates.
