Changliang Guo - Academia.edu (original) (raw)

Papers by Changliang Guo

Biomedical Optics Express, 2018

We report a depth-extended, high-resolution fluorescence microscopy system based on interfering B... more We report a depth-extended, high-resolution fluorescence microscopy system based on interfering Bessel beams generated with double-ring phase (DRiP) modulation. The DRiP method effectively suppresses the Bessel side lobes, exhibiting a high resolution of the main lobe throughout a four-to five-fold improved depth of focus (DOF), compared to conventional wide-field microscopy. We showed both theoretically and experimentally the generation and propagation of a DRiP point-spread function (DRiP-PSF) of the imaging system. We further developed an approach for creating an axially-uniform DRiP-PSF and successfully demonstrated diffraction-limited, depth-extended imaging of cellular structures. We expect the DRiP method to contribute to the fast-developing field of non-diffractingbeam-enabled optical microscopy and be useful for various types of imaging modalities.

Biophotonics Congress: Optics in the Life Sciences Congress 2019 (BODA,BRAIN,NTM,OMA,OMP), 2019

Frontiers in Optics 2017, 2017

We report a high-resolution light-field microscopy (LFM) system using a focused optical design. T... more We report a high-resolution light-field microscopy (LFM) system using a focused optical design. The system has been characterized both numerically and experimentally. 3D volumetric imaging of cellular structures has been demonstrated.

Biophotonics Congress: Optics in the Life Sciences Congress 2019 (BODA,BRAIN,NTM,OMA,OMP), 2019

sCMOS cameras are very appealing for fluorescence microscopy but they suffer from high readout no... more sCMOS cameras are very appealing for fluorescence microscopy but they suffer from high readout noise. We propose a non-iterative, fast, and unsupervised algorithm that erases sCMOS noise without losing the quantitative information of fluorescence signal.

Optica, 2020

We introduce Airy-beam tomographic microscopy (ATM) for high-resolution, volumetric, inertia-free... more We introduce Airy-beam tomographic microscopy (ATM) for high-resolution, volumetric, inertia-free imaging of biological specimens. The work exploits the highly adjustable Airy trajectories in the 3D space, transforming the conventional telecentric wide-field imaging scheme that requires sample or focal-plane scanning to acquire 3D information. The results present a consistent near-diffraction-limited 3D resolution across a tenfold extended imaging depth compared to wide-field microscopy. We anticipate the strategy to not only offer a promising paradigm for 3D optical microscopy, but also be translated to other non-optical waveforms.

Optics Express, 2019

Lensless imaging based on multi-wavelength phase retrieval becomes a promising technology widely ... more Lensless imaging based on multi-wavelength phase retrieval becomes a promising technology widely used as it has simple acquisition, miniaturized size and low-cost setup. However, measuring the sample-to-sensor distance with high accuracy, which is the key for high-resolution reconstruction, is still a challenge. In this work, we propose a multi-wavelength criterion to realize autofocusing modulation, i.e., achieving much higher accuracy in determining the sample-to-sensor distance, compared to the conventional methods. Three beams in different spectrums are adopted to illuminate the sample, and the resulting holograms are recorded by a CCD camera. The patterns calculated by performing back propagation of the recorded holograms, with exhaustively searched sample-to-sensor distance value, are adopted to access the criterion. Image sharpness can be accessed and the optimal sample-to-sensor distance can be finely determined by targeting the valley of the curve given by the criterion. Through our novel multi-wavelength based autofocusing strategy and executing further phase retrieval process, high-resolution images can be finally retrieved. The applicability and robustness of our method is validated both in simulations and experiments. Our technique provides a useful tool for multi-wavelength lensless imaging under limited experimental conditions.

Biomedical Optics Express, 2019

Visualizing diverse anatomical and functional traits that span many spatial scales with high spat... more Visualizing diverse anatomical and functional traits that span many spatial scales with high spatio-temporal resolution provides insights into the fundamentals of living organisms. Light-field microscopy (LFM) has recently emerged as a scanning-free, scalable method that allows for high-speed, volumetric functional brain imaging. Given those promising applications at the tissue level, at its other extreme, this highly-scalable approach holds great potential for observing structures and dynamics in single-cell specimens. However, the challenge remains for current LFM to achieve a subcellular level, neardiffraction-limited 3D spatial resolution. Here, we report high-resolution LFM (HR-LFM) for live-cell imaging with a resolution of 300-700 nm in all three dimensions, an imaging depth of several micrometers, and a volume acquisition time of milliseconds. We demonstrate the technique by imaging various cellular dynamics and structures and tracking single particles. The method may advance LFM as a particularly useful tool for understanding biological systems at multiple spatio-temporal levels.

Applied optics, 2018

A method to measure the refractive index of an optically flat, regularly shaped slab of glass usi... more A method to measure the refractive index of an optically flat, regularly shaped slab of glass using speckle correlation-based techniques is reported. The intensity of the diffraction field of the diffuser is captured by a CCD both with and without the glass present. As the position of the peak correlation coefficient is quantitatively related to the change in optical path length arising due to the presence of the glass, the refractive index of the glass can be evaluated by cross-correlating the two captured images. The theoretical correlation function that describes the effects of such an optical path length change is discussed, and the resulting speckle decorrelation function derived. Two glass samples are measured to demonstrate the accuracy and robustness of the proposed technique.

Applied optics, 2018

In general, the holographic grating refractive index profiles in photopolymer materials are not i... more In general, the holographic grating refractive index profiles in photopolymer materials are not identical to the exposing pattern. During exposure, high harmonics of the fundamental refractive index period are generated within the layer volume. A set of equations to calculate the amplitudes of the higher harmonics of refractive index induced in the grating is introduced. Then, an algorithm involving the use of the 3D nonlocal photopolymerization-driven diffusion model is presented and applied to calculate the resulting grating diffraction efficiencies. The experimental observation that the grating diffraction efficiency cannot reach the theoretical maximum value (η=100%) and that, in the case of over-modulation, the minimum value (η=0%) is also never achieved, are explained theoretically. The predictions of the simulations are also fit to experimental data for an acrylamide/polyvinyl alcohol photopolymer material with good agreement being achieved.

Optical Engineering, 2017

The linear canonical transform (LCT) is used in modeling a coherent light field propagation throu... more The linear canonical transform (LCT) is used in modeling a coherent light field propagation through first-order optical systems. Recently, a generic optical system, known as the Quadratic Phase Encoding System (QPES), for encrypting a two-dimensional (2D) image has been reported. In such systems, two random phase keys and the individual LCT parameters (α, β, γ) serve as secret keys of the cryptosystem. It is important that such encryption systems also satisfies some dynamic security properties. In this work, we therefore examine such systems using two cryptographic evaluation methods, the avalanche effect and bit independence criterion, which indicate the degree of security of the cryptographic algorithms using QPES. We compared our simulation results with the conventional Fourier and the Fresnel transform based DRPE systems. The results show that the LCT based DRPE has an excellent avalanche and bit independence characteristics compared to the conventional Fourier and Fresnel based encryption systems.

Scientific reports, Jan 6, 2017

We report a light-field based method that allows the optical encryption of three-dimensional (3D)... more We report a light-field based method that allows the optical encryption of three-dimensional (3D) volumetric information at the microscopic scale in a single 2D light-field image. The system consists of a microlens array and an array of random phase/amplitude masks. The method utilizes a wave optics model to account for the dominant diffraction effect at this new scale, and the system point-spread function (PSF) serves as the key for encryption and decryption. We successfully developed and demonstrated a deconvolution algorithm to retrieve both spatially multiplexed discrete data and continuous volumetric data from 2D light-field images. Showing that the method is practical for data transmission and storage, we obtained a faithful reconstruction of the 3D volumetric information from a digital copy of the encrypted light-field image. The method represents a new level of optical encryption, paving the way for broad industrial and biomedical applications in processing and securing 3D d...

Journal of Optics, 2016

Information security and authentication are important challenges facing our society. Recent attac... more Information security and authentication are important challenges facing our society. Recent attacks by hackers on the databases of large commercial and financial companies have demonstrated that more research and developments of advanced approaches are necessary to deny unauthorized access to critical data. Free space optical technology has been investigated by many researchers in information security, encryption, and authentication. The main motivation for using optics and photonics for information security is that optical waveforms possess many complex degrees of freedom such as amplitude, phase, polarization, large bandwidth, nonlinear transformations, quantum properties of photons, and multiplexing that can be combined in many ways to make the information encryption more secure and more difficult to attack. This roadmap article presents an overview of the potential, recent advances, and the challenges of optical security and encryption using free space optics. The roadmap on optical security is comprised of six categories that together include 16 short sections written by authors who have made relevant contributions in this field. The first category of this roadmap describes novel encryption approaches, including secure optical sensing which summarizes double random phase encryption applications and flaws [Yamaguchi], digital holographic encryption in free space optical technique which describes encryption using multidimensional digital holography [Nomura], simultaneous encryption of multiple signals [Pérez-Cabré], asymmetric methods based on information truncation [Nishchal], and dynamic encryption of video sequences [Torroba]. Asymmetric and one-way cryptosystems are analyzed by Peng. The second category is on compression for encryption. In their respective contributions, Alfalou and Stern propose similar goals involving compressed data and compressive sensing encryption. The very important area of cryptanalysis is the topic of the third category with two sections: Sheridan reviews phase retrieval algorithms to perform different attacks, whereas Situ discusses nonlinear optical encryption techniques and the development of a rigorous optical information security theory. The fourth category with two contributions reports how encryption could be implemented in the nano-or microscale. Naruse discusses the use of nanostructures in security applications and Carnicer proposes encoding information in a tightly focused beam. In the fifth category, encryption based on ghost imaging using single-pixel detectors is also considered. In particular, the authors [Chen, Tajahuerce] emphasize the need for more specialized hardware and image processing algorithms. Finally, in the sixth category, Mosk and Javidi analyze in their corresponding papers how quantum imaging can benefit optical encryption systems. Sources that use few photons make encryption systems much more difficult to attack, providing a secure method for authentication. 15. Multiple-scattering materials as physical unclonable functions 16. Optical security and encryption with quantum imaging Plaintext image Mapping Secret parameter (Projection to higher dimensional vector) Transform Plaintext data Projected data (high dimensionality) Transformed data Encryption key Ciphertext data Vector Rotation Decryption key Vector Rotation Recovered image Nonlinear Mapping (Dimensionality reduction) Inverse Transform Decrypted data Projected data (high dimensionality) Transformed data Encryption process Reconstruction process References Figure 2-Secure sensing system examples. Upper and middle: registration and verification steps of the optical cancellable biometrics system. Bottom: an example of encrypted sensing system.

Imaging and Applied Optics 2016, 2016

A maximum likelihood estimator is derived to reconstruct a 3D scene captured under photons starve... more A maximum likelihood estimator is derived to reconstruct a 3D scene captured under photons starved ambiences using computational integral imaging system. Here, we present a method to discard the defocused sparse-samples from the reconstructed 3D sectional images.

Frontiers in Optics 2015, 2015

A method for beam self-cleanup is introduced by use of self-written waveguides in a photopolymer,... more A method for beam self-cleanup is introduced by use of self-written waveguides in a photopolymer, acrylamide/polyvinyl alcohol. This work opens the door to study self-developing light cleanup and its further applications.

Optics express, Jan 15, 2015

We present a method of securing multispectral 3D photon-counted integral imaging (PCII) using cla... more We present a method of securing multispectral 3D photon-counted integral imaging (PCII) using classical Hartley Transform (HT) based encryption by employing optical interferometry. This method has the simultaneous advantages of minimizing complexity by eliminating the need for holography recording and addresses the phase sensitivity problem encountered when using digital cameras. These together with single-channel multispectral 3D data compactness, the inherent properties of the classical photon counting detection model, i.e. sparse sensing and the capability for nonlinear transformation, permits better authentication of the retrieved 3D scene at various depth cues. Furthermore, the proposed technique works for both spatially and temporally incoherent illumination. To validate the proposed technique simulations were carried out for both the 2D and 3D cases. Experimental data is processed and the results support the feasibility of the encryption method.

Applied optics, Jan 20, 2015

Two modified Gerchberg-Saxton (GS) iterative phase retrieval algorithms are proposed. The first w... more Two modified Gerchberg-Saxton (GS) iterative phase retrieval algorithms are proposed. The first we refer to as the spatial phase perturbation GS algorithm (SPP GSA). The second is a combined GS hybrid input-output algorithm (GS/HIOA). In this paper (Part I), it is demonstrated that the SPP GS and GS/HIO algorithms are both much better at avoiding stagnation during phase retrieval, allowing them to successfully locate superior solutions compared with either the GS or the HIO algorithms. The performances of the SPP GS and GS/HIO algorithms are also compared. Then, the error reduction (ER) algorithm is combined with the HIO algorithm (ER/HIOA) to retrieve the input object image and the phase, given only some knowledge of its extent and the amplitude in the Fourier domain. In Part II, the algorithms developed here are applied to carry out known plaintext and ciphertext attacks on amplitude encoding and phase encoding double random phase encryption systems. Significantly, ER/HIOA is then...

Frontiers in Optics 2015, 2015

We examine the sparse-sensing mechanism of compressive sensing (CS) systems with the linear canon... more We examine the sparse-sensing mechanism of compressive sensing (CS) systems with the linear canonical transform based DRPE system. Encrypted data is randomly sampled using CS theory. Experimental results demonstrate the feasibility of the proposed technique.

Applications of Digital Image Processing XXXVIII, 2015

In this paper, a new practical technique is presented based on digital holography, for the recons... more In this paper, a new practical technique is presented based on digital holography, for the reconstruction of a wave front from three intensity recordings. Combining the off-axis Fourier filtering technique with boundary detection and iterative phase retrieval algorithms, it is shown how problems such as elimination of the twin image can be overcome. The proposed methods deal with also the issues of feasibility and accuracy associated with off-axis Fourier spatial filtering (OFSF), and those of cost and alignment associated with phase shifting interferometry (PSI). Problems associated with working with diffuse objects are also overcome.

Optics Communications, 2014

ABSTRACT A novel optical encryption method is proposed involving double image encryption in which... more ABSTRACT A novel optical encryption method is proposed involving double image encryption in which one image is introduced as the pseudo image while the other is the original object image. The Double Random Phase Encoding technique is used to encrypt both the pseudo and object images into complex images. A unique binary image is then employed to first generate the random phase key for the object image encryption and then to embed the encrypted object image into the encrypted pseudo image, which acts as host image. Both the second random phase mask used for encoding the pseudo image and the binary image act as encryption keys. If an attacker attempts to crack the random phase key and decrypt the original object image, the pseudo image will be obtained instead. Simulation results and robustness tests are performed which demonstrate the feasibility of the algorithm.

Applied optics, Jan 20, 2015

The modified iterative phase retrieval algorithms developed in Part I [Guo et al., Appl. Opt.54, ... more The modified iterative phase retrieval algorithms developed in Part I [Guo et al., Appl. Opt.54, 4698 (2015)] are applied to perform known plaintext and ciphertext attacks on amplitude encoding and phase encoding Fourier-transform-based double random phase encryption (DRPE) systems. It is shown that the new algorithms can retrieve the two random phase keys (RPKs) perfectly. The performances of the algorithms are tested by using the retrieved RPKs to decrypt a set of different ciphertexts encrypted using the same RPKs. Significantly, it is also shown that the DRPE system is, under certain conditions, vulnerable to ciphertext-only attack, i.e., in some cases an attacker can decrypt DRPE data successfully when only the ciphertext is intercepted.

Biomedical Optics Express, 2018

We report a depth-extended, high-resolution fluorescence microscopy system based on interfering B... more We report a depth-extended, high-resolution fluorescence microscopy system based on interfering Bessel beams generated with double-ring phase (DRiP) modulation. The DRiP method effectively suppresses the Bessel side lobes, exhibiting a high resolution of the main lobe throughout a four-to five-fold improved depth of focus (DOF), compared to conventional wide-field microscopy. We showed both theoretically and experimentally the generation and propagation of a DRiP point-spread function (DRiP-PSF) of the imaging system. We further developed an approach for creating an axially-uniform DRiP-PSF and successfully demonstrated diffraction-limited, depth-extended imaging of cellular structures. We expect the DRiP method to contribute to the fast-developing field of non-diffractingbeam-enabled optical microscopy and be useful for various types of imaging modalities.

Biophotonics Congress: Optics in the Life Sciences Congress 2019 (BODA,BRAIN,NTM,OMA,OMP), 2019

Frontiers in Optics 2017, 2017

We report a high-resolution light-field microscopy (LFM) system using a focused optical design. T... more We report a high-resolution light-field microscopy (LFM) system using a focused optical design. The system has been characterized both numerically and experimentally. 3D volumetric imaging of cellular structures has been demonstrated.

Biophotonics Congress: Optics in the Life Sciences Congress 2019 (BODA,BRAIN,NTM,OMA,OMP), 2019

sCMOS cameras are very appealing for fluorescence microscopy but they suffer from high readout no... more sCMOS cameras are very appealing for fluorescence microscopy but they suffer from high readout noise. We propose a non-iterative, fast, and unsupervised algorithm that erases sCMOS noise without losing the quantitative information of fluorescence signal.

Optica, 2020

We introduce Airy-beam tomographic microscopy (ATM) for high-resolution, volumetric, inertia-free... more We introduce Airy-beam tomographic microscopy (ATM) for high-resolution, volumetric, inertia-free imaging of biological specimens. The work exploits the highly adjustable Airy trajectories in the 3D space, transforming the conventional telecentric wide-field imaging scheme that requires sample or focal-plane scanning to acquire 3D information. The results present a consistent near-diffraction-limited 3D resolution across a tenfold extended imaging depth compared to wide-field microscopy. We anticipate the strategy to not only offer a promising paradigm for 3D optical microscopy, but also be translated to other non-optical waveforms.

Optics Express, 2019

Lensless imaging based on multi-wavelength phase retrieval becomes a promising technology widely ... more Lensless imaging based on multi-wavelength phase retrieval becomes a promising technology widely used as it has simple acquisition, miniaturized size and low-cost setup. However, measuring the sample-to-sensor distance with high accuracy, which is the key for high-resolution reconstruction, is still a challenge. In this work, we propose a multi-wavelength criterion to realize autofocusing modulation, i.e., achieving much higher accuracy in determining the sample-to-sensor distance, compared to the conventional methods. Three beams in different spectrums are adopted to illuminate the sample, and the resulting holograms are recorded by a CCD camera. The patterns calculated by performing back propagation of the recorded holograms, with exhaustively searched sample-to-sensor distance value, are adopted to access the criterion. Image sharpness can be accessed and the optimal sample-to-sensor distance can be finely determined by targeting the valley of the curve given by the criterion. Through our novel multi-wavelength based autofocusing strategy and executing further phase retrieval process, high-resolution images can be finally retrieved. The applicability and robustness of our method is validated both in simulations and experiments. Our technique provides a useful tool for multi-wavelength lensless imaging under limited experimental conditions.

Biomedical Optics Express, 2019

Visualizing diverse anatomical and functional traits that span many spatial scales with high spat... more Visualizing diverse anatomical and functional traits that span many spatial scales with high spatio-temporal resolution provides insights into the fundamentals of living organisms. Light-field microscopy (LFM) has recently emerged as a scanning-free, scalable method that allows for high-speed, volumetric functional brain imaging. Given those promising applications at the tissue level, at its other extreme, this highly-scalable approach holds great potential for observing structures and dynamics in single-cell specimens. However, the challenge remains for current LFM to achieve a subcellular level, neardiffraction-limited 3D spatial resolution. Here, we report high-resolution LFM (HR-LFM) for live-cell imaging with a resolution of 300-700 nm in all three dimensions, an imaging depth of several micrometers, and a volume acquisition time of milliseconds. We demonstrate the technique by imaging various cellular dynamics and structures and tracking single particles. The method may advance LFM as a particularly useful tool for understanding biological systems at multiple spatio-temporal levels.

Applied optics, 2018

A method to measure the refractive index of an optically flat, regularly shaped slab of glass usi... more A method to measure the refractive index of an optically flat, regularly shaped slab of glass using speckle correlation-based techniques is reported. The intensity of the diffraction field of the diffuser is captured by a CCD both with and without the glass present. As the position of the peak correlation coefficient is quantitatively related to the change in optical path length arising due to the presence of the glass, the refractive index of the glass can be evaluated by cross-correlating the two captured images. The theoretical correlation function that describes the effects of such an optical path length change is discussed, and the resulting speckle decorrelation function derived. Two glass samples are measured to demonstrate the accuracy and robustness of the proposed technique.

Applied optics, 2018

In general, the holographic grating refractive index profiles in photopolymer materials are not i... more In general, the holographic grating refractive index profiles in photopolymer materials are not identical to the exposing pattern. During exposure, high harmonics of the fundamental refractive index period are generated within the layer volume. A set of equations to calculate the amplitudes of the higher harmonics of refractive index induced in the grating is introduced. Then, an algorithm involving the use of the 3D nonlocal photopolymerization-driven diffusion model is presented and applied to calculate the resulting grating diffraction efficiencies. The experimental observation that the grating diffraction efficiency cannot reach the theoretical maximum value (η=100%) and that, in the case of over-modulation, the minimum value (η=0%) is also never achieved, are explained theoretically. The predictions of the simulations are also fit to experimental data for an acrylamide/polyvinyl alcohol photopolymer material with good agreement being achieved.

Optical Engineering, 2017

The linear canonical transform (LCT) is used in modeling a coherent light field propagation throu... more The linear canonical transform (LCT) is used in modeling a coherent light field propagation through first-order optical systems. Recently, a generic optical system, known as the Quadratic Phase Encoding System (QPES), for encrypting a two-dimensional (2D) image has been reported. In such systems, two random phase keys and the individual LCT parameters (α, β, γ) serve as secret keys of the cryptosystem. It is important that such encryption systems also satisfies some dynamic security properties. In this work, we therefore examine such systems using two cryptographic evaluation methods, the avalanche effect and bit independence criterion, which indicate the degree of security of the cryptographic algorithms using QPES. We compared our simulation results with the conventional Fourier and the Fresnel transform based DRPE systems. The results show that the LCT based DRPE has an excellent avalanche and bit independence characteristics compared to the conventional Fourier and Fresnel based encryption systems.

Scientific reports, Jan 6, 2017

We report a light-field based method that allows the optical encryption of three-dimensional (3D)... more We report a light-field based method that allows the optical encryption of three-dimensional (3D) volumetric information at the microscopic scale in a single 2D light-field image. The system consists of a microlens array and an array of random phase/amplitude masks. The method utilizes a wave optics model to account for the dominant diffraction effect at this new scale, and the system point-spread function (PSF) serves as the key for encryption and decryption. We successfully developed and demonstrated a deconvolution algorithm to retrieve both spatially multiplexed discrete data and continuous volumetric data from 2D light-field images. Showing that the method is practical for data transmission and storage, we obtained a faithful reconstruction of the 3D volumetric information from a digital copy of the encrypted light-field image. The method represents a new level of optical encryption, paving the way for broad industrial and biomedical applications in processing and securing 3D d...

Journal of Optics, 2016

Information security and authentication are important challenges facing our society. Recent attac... more Information security and authentication are important challenges facing our society. Recent attacks by hackers on the databases of large commercial and financial companies have demonstrated that more research and developments of advanced approaches are necessary to deny unauthorized access to critical data. Free space optical technology has been investigated by many researchers in information security, encryption, and authentication. The main motivation for using optics and photonics for information security is that optical waveforms possess many complex degrees of freedom such as amplitude, phase, polarization, large bandwidth, nonlinear transformations, quantum properties of photons, and multiplexing that can be combined in many ways to make the information encryption more secure and more difficult to attack. This roadmap article presents an overview of the potential, recent advances, and the challenges of optical security and encryption using free space optics. The roadmap on optical security is comprised of six categories that together include 16 short sections written by authors who have made relevant contributions in this field. The first category of this roadmap describes novel encryption approaches, including secure optical sensing which summarizes double random phase encryption applications and flaws [Yamaguchi], digital holographic encryption in free space optical technique which describes encryption using multidimensional digital holography [Nomura], simultaneous encryption of multiple signals [Pérez-Cabré], asymmetric methods based on information truncation [Nishchal], and dynamic encryption of video sequences [Torroba]. Asymmetric and one-way cryptosystems are analyzed by Peng. The second category is on compression for encryption. In their respective contributions, Alfalou and Stern propose similar goals involving compressed data and compressive sensing encryption. The very important area of cryptanalysis is the topic of the third category with two sections: Sheridan reviews phase retrieval algorithms to perform different attacks, whereas Situ discusses nonlinear optical encryption techniques and the development of a rigorous optical information security theory. The fourth category with two contributions reports how encryption could be implemented in the nano-or microscale. Naruse discusses the use of nanostructures in security applications and Carnicer proposes encoding information in a tightly focused beam. In the fifth category, encryption based on ghost imaging using single-pixel detectors is also considered. In particular, the authors [Chen, Tajahuerce] emphasize the need for more specialized hardware and image processing algorithms. Finally, in the sixth category, Mosk and Javidi analyze in their corresponding papers how quantum imaging can benefit optical encryption systems. Sources that use few photons make encryption systems much more difficult to attack, providing a secure method for authentication. 15. Multiple-scattering materials as physical unclonable functions 16. Optical security and encryption with quantum imaging Plaintext image Mapping Secret parameter (Projection to higher dimensional vector) Transform Plaintext data Projected data (high dimensionality) Transformed data Encryption key Ciphertext data Vector Rotation Decryption key Vector Rotation Recovered image Nonlinear Mapping (Dimensionality reduction) Inverse Transform Decrypted data Projected data (high dimensionality) Transformed data Encryption process Reconstruction process References Figure 2-Secure sensing system examples. Upper and middle: registration and verification steps of the optical cancellable biometrics system. Bottom: an example of encrypted sensing system.

Imaging and Applied Optics 2016, 2016

A maximum likelihood estimator is derived to reconstruct a 3D scene captured under photons starve... more A maximum likelihood estimator is derived to reconstruct a 3D scene captured under photons starved ambiences using computational integral imaging system. Here, we present a method to discard the defocused sparse-samples from the reconstructed 3D sectional images.

Frontiers in Optics 2015, 2015

A method for beam self-cleanup is introduced by use of self-written waveguides in a photopolymer,... more A method for beam self-cleanup is introduced by use of self-written waveguides in a photopolymer, acrylamide/polyvinyl alcohol. This work opens the door to study self-developing light cleanup and its further applications.

Optics express, Jan 15, 2015

We present a method of securing multispectral 3D photon-counted integral imaging (PCII) using cla... more We present a method of securing multispectral 3D photon-counted integral imaging (PCII) using classical Hartley Transform (HT) based encryption by employing optical interferometry. This method has the simultaneous advantages of minimizing complexity by eliminating the need for holography recording and addresses the phase sensitivity problem encountered when using digital cameras. These together with single-channel multispectral 3D data compactness, the inherent properties of the classical photon counting detection model, i.e. sparse sensing and the capability for nonlinear transformation, permits better authentication of the retrieved 3D scene at various depth cues. Furthermore, the proposed technique works for both spatially and temporally incoherent illumination. To validate the proposed technique simulations were carried out for both the 2D and 3D cases. Experimental data is processed and the results support the feasibility of the encryption method.

Applied optics, Jan 20, 2015

Two modified Gerchberg-Saxton (GS) iterative phase retrieval algorithms are proposed. The first w... more Two modified Gerchberg-Saxton (GS) iterative phase retrieval algorithms are proposed. The first we refer to as the spatial phase perturbation GS algorithm (SPP GSA). The second is a combined GS hybrid input-output algorithm (GS/HIOA). In this paper (Part I), it is demonstrated that the SPP GS and GS/HIO algorithms are both much better at avoiding stagnation during phase retrieval, allowing them to successfully locate superior solutions compared with either the GS or the HIO algorithms. The performances of the SPP GS and GS/HIO algorithms are also compared. Then, the error reduction (ER) algorithm is combined with the HIO algorithm (ER/HIOA) to retrieve the input object image and the phase, given only some knowledge of its extent and the amplitude in the Fourier domain. In Part II, the algorithms developed here are applied to carry out known plaintext and ciphertext attacks on amplitude encoding and phase encoding double random phase encryption systems. Significantly, ER/HIOA is then...

Frontiers in Optics 2015, 2015

We examine the sparse-sensing mechanism of compressive sensing (CS) systems with the linear canon... more We examine the sparse-sensing mechanism of compressive sensing (CS) systems with the linear canonical transform based DRPE system. Encrypted data is randomly sampled using CS theory. Experimental results demonstrate the feasibility of the proposed technique.

Applications of Digital Image Processing XXXVIII, 2015

In this paper, a new practical technique is presented based on digital holography, for the recons... more In this paper, a new practical technique is presented based on digital holography, for the reconstruction of a wave front from three intensity recordings. Combining the off-axis Fourier filtering technique with boundary detection and iterative phase retrieval algorithms, it is shown how problems such as elimination of the twin image can be overcome. The proposed methods deal with also the issues of feasibility and accuracy associated with off-axis Fourier spatial filtering (OFSF), and those of cost and alignment associated with phase shifting interferometry (PSI). Problems associated with working with diffuse objects are also overcome.

Optics Communications, 2014

ABSTRACT A novel optical encryption method is proposed involving double image encryption in which... more ABSTRACT A novel optical encryption method is proposed involving double image encryption in which one image is introduced as the pseudo image while the other is the original object image. The Double Random Phase Encoding technique is used to encrypt both the pseudo and object images into complex images. A unique binary image is then employed to first generate the random phase key for the object image encryption and then to embed the encrypted object image into the encrypted pseudo image, which acts as host image. Both the second random phase mask used for encoding the pseudo image and the binary image act as encryption keys. If an attacker attempts to crack the random phase key and decrypt the original object image, the pseudo image will be obtained instead. Simulation results and robustness tests are performed which demonstrate the feasibility of the algorithm.

Applied optics, Jan 20, 2015

The modified iterative phase retrieval algorithms developed in Part I [Guo et al., Appl. Opt.54, ... more The modified iterative phase retrieval algorithms developed in Part I [Guo et al., Appl. Opt.54, 4698 (2015)] are applied to perform known plaintext and ciphertext attacks on amplitude encoding and phase encoding Fourier-transform-based double random phase encryption (DRPE) systems. It is shown that the new algorithms can retrieve the two random phase keys (RPKs) perfectly. The performances of the algorithms are tested by using the retrieved RPKs to decrypt a set of different ciphertexts encrypted using the same RPKs. Significantly, it is also shown that the DRPE system is, under certain conditions, vulnerable to ciphertext-only attack, i.e., in some cases an attacker can decrypt DRPE data successfully when only the ciphertext is intercepted.