Underwater ghost imaging with detection distance up to 9.3 attenuation lengths.

Underwater ghost imaging LiDAR is an effective method of underwater detection. In this research, theoretical and experimental investigations were conducted on underwater ghost imaging, combining the underwater optical field transmission model with the inherent optical parameters of a water body. In addition, the Wells model and the approximate Sahu-Shanmugam scattering phase function were used to create a model for underwater optical transmission.

Fourier-transform ghost imaging with super-Rayleigh speckles.

Ghost imaging based on the high-order correlation of optical field has developed rapidly and has been extended to the x-ray region. However, the limited flux leads to severe image deterioration. Here, an approach of Fourier-transform ghost imaging with super-Rayleigh speckles is proposed to realize high quality ghost imaging at low photon flux level.

Path sampling and integration method to calculate speckle patterns.

A stable speckle pattern is generated when a coherent beam illuminates a stationary scattering medium that contains numerous scatterers with fixed positions. To date, there has been no valid method to the best of our knowledge for calculating the speckle pattern of a macro medium with a large number of scatterers. Here, a new method based on possible path sampling with corresponding weights and coherent superposition is presented for the simulation of optical field propagation in a scattering medium and output speckle patterns.

Imaging and positioning through scattering media with double-helix point spread function engineering.

Significance: Double-helix point spread function (DH-PSF) microscopy has been developed for three-dimensional (3D) localization and imaging at super-resolution but usually in environments with no or weak scattering. To date, super-resolution imaging through turbid media has not been reported.

Aim: We aim to explore the potential of DH-PSF microscopy in the imaging and localization of targets in scattering environments for improved 3D localization accuracy and imaging quality.

Far-field super-resolution ghost imaging with a deep neural network constraint.

Ghost imaging (GI) facilitates image acquisition under low-light conditions by single-pixel measurements and thus has great potential in applications in various fields ranging from biomedical imaging to remote sensing. However, GI usually requires a large amount of single-pixel samplings in order to reconstruct a high-resolution image, imposing a practical limit for its applications. Here we propose a far-field super-resolution GI technique that incorporates the physical model for GI image formation into a deep neural network.

Temporal characterization of electron dynamics in attosecond XUV and infrared laser fields.

We use a Wigner distribution-like function based on the strong field approximation theory to obtain the time-energy distributions and the ionization time distributions of electrons ionized by an XUV pulse alone and in the presence of an infrared (IR) pulse. In the case of a single XUV pulse, although the overall shape of the ionization time distribution resembles the XUV-envelope, its detail shows dependence on the emission direction of the electron and the carrier-envelope phase of the pulse, which mainly results from the low-energy interference structure. It is further found that the electron from the counter-rotating term plays an important role in the interference.

Spectral polarization camera based on ghost imaging via sparsity constraints.

A spectral polarization camera based on ghost imaging via sparsity constraints (GISC) is presented. The proposed imager modulates three-dimensional spatial and spectral information of the target into two-dimensional speckle patterns using a spatial random phase modulator and then acquires the speckle patterns at four linear polarization channels through a polarized CCD. The experimental results verify the feasibility of the system structure and reconstruction algorithm.

Experimental investigation of chirped amplitude modulation heterodyne ghost imaging.

We have constructed a chirped amplitude modulation heterodyne ghost imaging (CAM-HGI) experimental system that demonstrates a robust ability against background light in experiments. In the experiments, the background light is simulated by irradiating a spatiotemporal random modulated light field onto the target. The effects of background light, modulation depth and modulation duration of the signal light source on CAM-HGI are investigated experimentally.

Ghost imaging based on Y-net: a dynamic coding and decoding approach.

Ghost imaging incorporating deep learning technology has recently attracted much attention in the optical imaging field. However, deterministic illumination and multiple exposure are still essential in most scenarios. Here we propose a ghost imaging scheme based on a novel dynamic decoding deep learning framework (Y-net), which works well under both deterministic and indeterministic illumination.

Expansion of the FOV in speckle autocorrelation imaging by spatial filtering.

Optical imaging through inhomogeneous media based on autocorrelations suffers from a limited field of view (FOV), since the optical memory effect (ME) of a scattering medium has its inherent angular extent. Here we successfully expand the angular ME range by exploiting a spatial filtering technique to select low-frequency components, mainly ballistic light and less scattered light, thereby increasing the FOV of the speckle autocorrelation imaging. Both a simulation and experimental verifications are presented.

Focal-plane three-dimensional imaging method based on temporal ghost imaging: a proof of concept simulation.

A new focal-plane three-dimensional (3D) imaging method based on temporal ghost imaging is proposed and demonstrated. By exploiting the advantages of temporal ghost imaging, this method enables the utilization of slow integrating cameras and facilitates 3D surface imaging within the framework of sequential flood-illumination and focal-plane detection. The depth information is achieved by a temporal correlation between received and reference signals with multiple-shot, and the reflectivity information is achieved by flash imaging with a single-shot.

Optimization of light fields in ghost imaging using dictionary learning.

Ghost imaging (GI) is a novel imaging technique based on the second-order correlation of light fields. Due to limited number of samplings in practice, traditional GI methods often reconstruct objects with unsatisfactory quality. To improve the imaging results, many reconstruction methods have been developed, yet the reconstruction quality is still fundamentally restricted by the modulated light fields.

Non-locally coded Fourier-transform ghost imaging.

A non-locally coded Fourier-transform ghost imaging (FGI) scheme and relevant coded phase retrieval method have been proposed to improve the image quality in ghost imaging. By inserting masks in the reference beam, the sample in the test beam is non-locally modulated, and coded Fourier-transform diffraction patterns of the sample are obtained via intensity correlation calculations between the two beams. Encoding and decoding procedures are incorporated in the phase retrieval process based on traditional hybrid input-output algorithm.

Bidirectional image transmission through physically thick scattering media using digital optical phase conjugation.

We demonstrate the feasibility of bidirectional image transmission through a physically thick scattering medium within its memory effect range by digital optical phase conjugation. We show the bidirectional transmission is not simply the consequence of optical reciprocity. We observe that when the spatial light modulator (the device performing the digital optical phase conjugation) is relayed to the middle plane of the medium, the memory effect will be fully exploited and thus the transmitted images will have maximum field of view (FOV).

Hyperspectral ghost imaging camera based on a flat-field grating.

A spectral camera based on ghost imaging via sparsity constraints (GISC) acquires a three-dimensional (3D) spatial-spectral data cube of the target through a two-dimensional (2D) detector in a single snapshot. However, the spectral and spatial resolution are interrelated because both of them are modulated by the same spatial random phase modulator. In this paper, we theoretically and experimentally demonstrate a system by equipping the GISC spectral camera with a flat-field grating to disperse the light fields before the spatial random phase modulator, hence consequently decoupling the spatial and spectral resolution.

Optical phase conjugation of diffused light with infinite gain by using gated two-color photorefractive crystal LiNbO:Cu:Ce.

Light focusing in multiple scattering circumstances is important in biomedical imaging, manipulation, and therapy. Until now, many traditional photorefractive crystals have been used to generate an optical phase conjugated wavefront in an analogue time-reversed optical focusing technology. However, owing to erasure of a volume hologram during a reading procedure, the optical energy gain can never reach unity, limiting its application in delivering more energy into a target area.

Author Correction: Non-invasive three-dimension control of light between turbid layers using a surface quasi-point light source for precorrection.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Spatial multiplexing reconstruction for Fourier-transform ghost imaging via sparsity constraints.

A spatial multiplexing reconstruction method has been proposed to improve the sampling efficiency and image quality of Fourier-transform ghost imaging. In this method, the sensing equation of Fourier-transform ghost imaging is established based on recombination and reutilization of the correlated intensity distributions of light fields. It is theoretically proved that the scale of the sensing matrix in the sensing equation can be greatly reduced, and spatial multiplexing combined with this matrix reduction provides the feasibility of ghost imaging with just a few measurements.

Effect of two-center interference on molecular ionization in multiphoton ionization regime.

Using solution of the full three-dimensional time-dependent Schrödinger equation (TDSE) in prolate spheroidal coordinates, we investigate the orientation dependence of ionization of H2+ in near-infrared laser fields. It is found that, the ionization probability decreases as a function of the alignment angle in tunneling ionization regime, while it ascends with the increase of orientation angle in multiphoton ionization regime for the internuclear distance R=2 a.u.

Non-invasive three-dimension control of light between turbid layers using a surface quasi-point light source for precorrection.

Manipulating light non-invasively through inhomogeneous media is an attractive goal in many disciplines. Wavefront shaping and optical phase conjugation can focus light to a point. Transmission matrix method can control light on multiple output modes simultaneously.

Quantum temporal imaging by four-wave mixing.

We investigate temporal imaging of broadband squeezed light by four-wave-mixing. We consider two possible imaging configurations: phase-conjugating (PC) and phase-preserving (PP). Both of these configurations have been successfully used for temporal imaging of classical temporal waveforms.

Pulse-compression ghost imaging lidar via coherent detection.

Ghost imaging (GI) lidar, as a novel remote sensing technique, has been receiving increasing interest in recent years. By combining pulse-compression technique and coherent detection with GI, we propose a new lidar system called pulse-compression GI lidar. Our analytical results, which are backed up by numerical simulations, demonstrate that pulse-compression GI lidar can obtain the target's spatial intensity distribution, range and moving velocity.

Fourier-Transform Ghost Imaging with Hard X Rays.

Knowledge gained through x-ray crystallography fostered structural determination of materials and greatly facilitated the development of modern science and technology in the past century. However, it is only applied to crystalline structures and cannot resolve noncrystalline materials. Here we demonstrate a novel lensless Fourier-transform ghost imaging method with pseudothermal hard x rays that extends x-ray crystallography to noncrystalline samples.