Global Information Transmission Model-Based Multiobjective Image Inversion Restoration Method for Space Diffractive Membrane Imaging Systems

Image degradation characteristics and restoration based on regularization for diffractive imaging

X-ray transmission imaging has been used in a variety of applications for high-resolution measurements based on shape and density. Similarly, X-ray diffraction (XRD) imaging has been used widely for molecular structure-based identification of materials. Combining these X-ray methods has the potential to provide high-resolution material identification, exceeding the capabilities of either modality alone. However, XRD imaging methods have been limited in application by their long measurement times and poor spatial resolution, which has generally precluded combined, rapid measurements of X-ray transmission and diffraction. In this work, we present a novel X-ray fan beam coded aperture transmission and diffraction imaging system, developed using commercially available components, for rapid and accurate non-destructive imaging of industrial and biomedical specimens. The imaging system uses a 160 kV Bremsstrahlung X-ray source while achieving a spatial resolution of ≈ 1 × 1 mm2 and a spectral accuracy of > 95% with only 15 s exposures per 150 mm fan beam slice. Applications of this technology are reported in geological imaging, pharmaceutical inspection, and medical diagnosis. The performance of the imaging system indicates improved material differentiation relative to transmission imaging alone at scan times suitable for a variety of industrial and biomedical applications.

In order to verify the technology of the membrane diffractive imaging system for Chinese next generation geo-stationary earth orbit (GEO) satellite, a series of ground experiments have been carried out using a membrane optical camera with 80 mm aperture (Φ80) lens. The inherent chromatic aberration due to diffractive imaging appears in the obtained data. To address the issue, an effective color restoration algorithm framework by matching, tailoring, and non-linearly stretching the image histograms is proposed in this letter. Experimental results show the proposed approach has good performances in color restoration of the diffractive optical images than previous methods. The effectiveness and robustness of the algorithm are also quantitatively assessed using various color deviation indexes. The results indicate that the chromatic aberration of diffractive images can be effectively removed by about 85%. Also, the proposed method presents reasonable computational efficiency.

Satellite imagery always has low-resolution causing poor application in practice because the serious degradation in imaging is resulted in many factors such as atmospheric turbulence, cloud, and aberration of optical system. To reconstruct the degraded remote sensing images with a high quality, we designed an algorithm to estimate the system modulation transfer function (MTF) accurately. Phase congruency is employed to detect the edges and corners of the image first, then the significant edges, which are utilized to estimate the edge spread function (ESF) using inclined edge method, are picked up from above features through a certain line detection measurement. An image restoration algorithm based on total variation (TV) is introduced to deconvolute the degraded image with the estimated MTF which is derived from the ESF. The experiments show that this method is adaptive and efficient to recover the remote sensing images taken from a Chinese Satellite. The restored images with a higher resolution and higher signal-to-noise ratio (SNR) will improve the applications greatly.

Oblique incidence is the normal working mode for diffractive optical elements (DOEs). The diffraction efficiency is very sensitive to the angle of incidence for multilayer diffractive optical elements (MLDOEs). Therefore, the design and diffraction efficiency analysis of MLDOEs with wide angles of incidence is of universal significance and practice. We propose an integral diffraction efficiency model for MLDOEs with wide angles of incidence in case of polychromatic light and then describe this corresponding optimal design in detail. It is shown that high diffraction efficiency can be realized by the surface micro-structure heights optimization, ensuring high modulation transfer function (MTF) for MLDOEs with wide angles of incidence in hybrid optical systems. On this basis, we present the optimal design process and simulation of an MLDOE working in visible waveband with optical plastic materials combination PMMA and POLYCARB as the two-layer substrates. The result shows that with this optimal design, we can achieve the maximum diffraction efficiency and minimum micro-structure heights, which makes the MLDOE design exactly over the entire waveband and wide angles of incidence especially for zoom hybrid optical system.

PurposeThis study aims to the information about consumer product quality and safety that can easily attract public attention and become the focus of public opinion. In recent years, the fast-growing social media have become an import platform for firms for releasing product quality and safety information and for firms and governments to hear public opinion.Design/methodology/approachTo explore how information about consumer product quality and safety gets disseminated and a public opinion is formed in social media, this paper proposes two information transmission models, one with government intervention and the other without government intervention, based on the theory of complex network. A simulation case study in MATLAB is conducted to verify the proposed models.FindingsInformation transmission models were constructed, one without government intervention and one with government intervention. The influence of information transmission with government intervention was analyzed. MATLAB was used to simulate the Barabasi and Albert (BA)-based model to consider event information level, government information level and possible panic population proportion. The government intervention effect was evaluated.Originality/valueBased on a complex network, the derived transmission rule can provide decision-making support for monitoring and managing Web information of consumer product quality and safety.

The experimental data allow us to determine the imaging quality of holographic gratings with photosensitive film using organic material based on a polyvinyl alcohol matrix doped with potassium dichromate and nickel (II) chloride hexahydrate. The diffraction efficiency is estimated by different spatial frequencies, and the readout image quality is analyzed by the modulation transfer function. The experiment is carried out, with and without voltage application, at different spatial frequencies to obtain the image quality of photosensitive film.

This paper introduces a novel lensless full colour diffractive computational imaging system with a planar Multilevel Phase Mask (MPM) as a diffractive optical element (DOE). The novelty concerns: a methodology of MPM design for improved depth of focus (DoF); design of PSFs for RGB imaging and an inverse imaging algorithm with sparse colour image modelling simultaneous for all RGB channels. MPMs are step-wise invariant. The cubic wavefront coding (WFC) is incorporated in MPMs with optimization of number of levels and width of invariant steps. This design of MPM makes the system robust with respect to defocus (improves DoF) and diminish chromatic aberrations typical for DOEs. Broadband multichannel test-images are exploited for design and testing of the lensless system. We consider two alternative optical setups: Wavelength Multiplexing (WM) and Wavelength Division (WD). In WM, the light beam is broadband multichannel with light sources radiating all wavelengths simultaneously and a CMOS sensor is equipped with a Bayer colour filter array (CFA) for registration of spectral measurements. In this setup, a single MPM is designed for the broadband multichannel light beams. In WD, separate exposures of RGB channels are registered by a broadband grey-scale CCD sensor. Different MPMs are designed for each of the RGB channels. Simulation experiments demonstrate the essentially extended DoF of the designed lensless systems and the advanced accuracy and quality of imaging with respect to the corresponding WM and WD systems with refractive lenses. Due to robustness of the designed lensless system to chromatic aberrations, this advantage has a place even with respect to the lens-system.

As the existing traffic information system based on the fixed traffic information center needs high cost for construct, and the other traffic information system based on inter vehicle communication pays more attention to safe driving information but pays less attention to traffic congestion information, especially for the traffic congestion information in the road network. This paper studies and puts forward a pattern for automatic traffic information service which realizes the function of automatic collection and dynamic transmission of traffic information in the road network on the basis of VANET, and with no need for fixed traffic information center. According to this pattern, we build the models for automatic collecting, integrating and processing, transmitting of traffic information, and automatic generating and dynamic updating of traffic information which covers the whole road network. Finally, in this paper, we also carry out traffic simulation for these models, analyze and evaluate rationality of these models and transmission effect.

The Internet of Vehicles (IoV) makes it possible to transmit information in real time between vehicles, providing a modern approach for autonomous driving, traffic safety, and other applications. Roadside units (RSUs) contribute to the enhancement of IoV's reliability and transmission efficiency, while mitigating the impact of low IoV penetration. The objective of RSU deployment optimization is to minimize the total cost with the premise of ensuring IoV reliability. We construct a distance-based reliability measure for IoV, which is expressed as the proportion of information transmitted in online mode to the total transmission distance. The distance distribution of the online and offline transmissions is computed using the information transmission model. A bi-objective optimization model is established with the objectives of minimizing the cost of RSU and maximizing the reliability of IoV. Meanwhile, based on variable probabilities of crossover and mutation, a nondomination level-based NSGA-II (NNSGA-II) is designed to improve the solving efficiency. Numerical results show the advantage of the proposed model over the models evaluated with the objective of reducing transmission time can be up to 18% in different traffic scenarios, and NNSGA-II is significantly more computationally efficient.

Due to the wave nature of diffraction, purely diffractive systems have been plagued by large chromatic and off-axis aberrations. Accordingly, there has not been much work in purely diffractive wideband imaging systems. In this paper, we present a method for the design and subsequent optimization of diffractive doublets for wideband, on-axis imaging. The method can most easily be explained with reference to Kato’s recent work[1], although the present work was arrived at independently.

Color correction with 3D lookup tables in diffractive optical imaging systems

A thorough and complete assessment of microstructure of materials requires a wide variety of analytical techniques, which should be sensitive to at all length scales - from mms to atomic scale. While there have been rapid advances in imaging and spectroscopy techniques for microstructural analysis - at all length scales, techniques for crystallographic analysis of microstructure have primarily relied on bulk x-ray/neutron diffraction and TEM. X-ray and neutron diffraction techniques, though very powerful, are primarily bulk techniques and extraction of local crystallography is formidable if not impossible. On the other hand, TEM diffraction techniques provide precise crystallographic information, but at a much smaller length-scale and suffer from poor statistics and tedious specimen preparation procedures. With the advent of commercially available electron backscattered diffraction (EBSD) and orientational imaging (OIM) systems for SEM, and sophisticated pattern recognition procedures, it is now possible to bridge the length-scale gap between bulk and TEM diffraction techniques.

Coded Aperture Snapshot Spectral Imaging (CASSI) is an effective tool to capture spectral images, which has the advantages of snapshot imaging, high luminous flux, high signal-to-noise ratio and low sampling frequency. However, conventional CASSI generally uses refractive prisms or gratings for spectral dispersion, which leads to the nonlinear dispersion phenomenon and the requirement of large detector chip respectively. To overcome these issues, conventional refractive prisms or gratings are replaced by an axially dispersive diffractive optical element (DOE, i.e., computational optics) together with a RGB Bayer filter (i.e., a color-coded aperture) in this study. Specifically, the spatial-spectral information of a test scene is jointly modulated by the DOE and the Bayer filter integrated with a sensor chip. A fully differentiable imaging model is built based on the principle of diffractive optics and the deep learning technology. Furthermore, an optimization design of the DOE with the coded aperture is realized through an end-to-end approach, the output spectral images of which are restored by a Res-Unet neural network. Several simulation results show that up to 31 high-fidelity spectral bands in the range of 400 to 700 nm with a good spatial and spectral resolution can be recovered by the proposed snapshot system.

Silver halide sensitized gelatin as a holographic recording material