We present a new method for recording off-axis digital Fourier holograms of three-dimensional objects under spatially incoherent illumination. The method is implemented by modifying the optical ...configuration of triangular interferometer. The recording properties and 3D reconstruction ability of the proposed method are investigated theoretically and experimentally. Multicolor holographic recording and reconstruction of spatially incoherent illuminated object are achieved by using the proposed off-axis Fourier triangular interferometer and monochromatic digital camera. Only three holograms are sufficient to rebuild a color image without zero-order and twin image disturbing effect. Combining with some image fusion skills during reconstruction, the reconstructed color images with satisfied quality are demonstrated.
Extending depth-of-field (DOF) of the imaging system without modifying the structure and sacrificing imaging performances of the optical system is of great significance to broaden the capability and ...application of the imaging system. In this paper, the interferenceless coded aperture correlation holography(I-COACH) is developed to be a large-depth incoherent imaging system by employing an annular multi-focal coded phase mask (AM-CPM). Based on the analyses of axial defocus characteristics in I-COACH, the defocus compensation function is defined, the AM-CPM is designed and multiplexed on the system optical pupil, which plays the role of a gradual lens. In AM-CPM, multi-annular zones with different focal lengths are used to compensate different axial defocus aberrations and adjacent annular zones have symmetric axial defocus aberration correction capability according to the imaging characteristics of the system. The simulations and experimental results fully demonstrate that the axial point spread function distribution of the system obtained by AM-CPM is continuous and the development method enables the extension of the DOF of the I-COACH system by only single exposure point spread hologram. This solution is expected to provide great potential in the field of microscopic imaging and other fields of that based on I-COACH system.
Integrated photonic devices and artificial intelligence have presented a significant opportunity for the advancement of optical computing in practical applications. Optical computing technology is a ...unique computing system based on optical devices and computing functions, which significantly differs from the traditional electronic computing technology. On the other hand, optical computing technology offers the advantages such as fast speed, low energy consumption, and high parallelism. Yet there are still challenges such as device integration and portability. In the burgeoning development of micro–nano optics technology, especially the deeply ingrained concept of metasurface technique, it provides an advanced platform for optical computing applications, including edge detection, image or motion recognition, logic computation, and on-chip optical computing. With the aim of providing a comprehensive introduction and perspective for optical computing metasurface applications, we review the recent research advances of optical computing, from nanostructure and computing methods to practical applications. In this work, we review the challenges and analysis of optical computing metasurfaces in engineering field and look forward to the future development trends of optical computing.
Existing ant colony optimization (ACO) for software testing cases generation is a very popular domain in software testing engineering. However, the traditional ACO has flaws, as early search ...pheromone is relatively scarce, search efficiency is low, search model is too simple, positive feedback mechanism is easy to porduce the phenomenon of stagnation and precocity. This paper introduces improved ACO for software testing cases generation: improved local pheromone update strategy for ant colony optimization, improved pheromone volatilization coefficient for ant colony optimization (IPVACO), and improved the global path pheromone update strategy for ant colony optimization (IGPACO). At last, we put forward a comprehensive improved ant colony optimization (ACIACO), which is based on all the above three methods. The proposed technique will be compared with random algorithm (RND) and genetic algorithm (GA) in terms of both efficiency and coverage. The results indicate that the improved method can effectively improve the search efficiency, restrain precocity, promote case coverage, and reduce the number of iterations.
Testing and verification of the interface between software components are particularly important due to the large number of complex interactions, which requires the traditional modeling languages to ...overcome the existing shortcomings in the aspects of temporal information description and software testing input controlling. This paper presents the real-time extended interface automata (RTEIA) which adds clearer and more detailed temporal information description by the application of time words. We also establish the input interface automaton for every input in order to solve the problems of input controlling and interface covering nimbly when applied in the software testing field. Detailed definitions of the RTEIA and the testing cases generation algorithm are provided in this paper. The feasibility and efficiency of this method have been verified in the testing of one real aircraft braking system.
Ghost imaging (GI) is an imaging method that reconstructs object information via light-intensity correlation measurements. The unconventional imaging mechanism of GI makes it suitable for imaging in ...scattering medium, for instance, turbid liquid, biological tissues, etc. However, the strong background noise in the reconstructed images is still the bottleneck problems. In this paper, we focus on the improvements of the reconstructions in underwater GI and propose a speckle decomposition and fusion method for suppressing the noise. The approach utilized computational ghost imaging framework and dictionary learning to acquire high- and low-frequency components that are better suited for image feature-based reconstruction. Furthermore, once the suitable threshold has been established, the speckles captured from the reference path are decomposed using the Nonsubsampled Contourlet Transform (NSCT). The acquired high- and low-frequency are then correlated with the overall optical intensity that captured by the bucket detectors. Ultimately, a multi-scale inverse NSCT transformation is employed to produce the final fusion-reconstructed image. The quantitative evaluation of the reconstructed image quality was conducted. In contrast to previous methodologies, the proposed method offers significant enhancements of the underwater GI imaging quality.
•A high-quality computational ghost imaging method for underwater has been developed. In our method, a general high-quality reconstruction mathematical model for the computational ghost imaging system is proposed, along with a speckle decomposition and fusion method aimed at suppressing noise.•In our method, the correlation operation entails transforming the speckle pattern from the spatial domain to the transform domain, which separates the speckle into high- and low-frequency components. This allows for the utilization of both high- and low-frequency speckle components to obtain detailed or approximate information with a SNR.•Our method is capable of addressing the issue of losing important information during ghost imaging. By maximizing the extraction of favorable information, it significantly enhances the quality of GI imaging.
•We developed a method by exploring the direct correlation of holograms in fluorescence self-interference digital holography for 3D localization and tracking of dynamic nanoparticles.•Phase-shifting ...is not necessary for the extraction of 3D spatial coordinates of the sample, so that the proposed method has an improved temporal resolution.•Experimental results shown that within a large imaging depth (>10 μm) our method exhibits a better isotropy in the three-dimensional localization accuracy.
Single-molecule localization microscopy (SMLM) has been applied as a powerful tool in the visualization of biological samples. The obtained details about the fine structures inside the cells or tissues, on the spatial scale of much smaller than the size that defined by the diffraction limit of the optical system, are important for the understanding of the dynamics and organization of the living process. In this paper, by exploring the direct correlation of real-valued holograms in fluorescence self-interference digital holography (SIDH), an imaging method is proposed for 3D localization and dynamic 3D tracking of nanoparticles. The trend of 3D localization accuracy under different axial positions is studied in detail. An appropriate mathematical model is used to fit the cross-correlation curve of the hologram to determine the axis coordinate of the point source. The validity of the proposed method is demonstrated in simulation and experiments. This method does not require phase shift technology. The 3D coordinates of particles can be obtained through a single real-valued hologram using the proposed algorithm. Therefore, we believe the developed method has unique advantages in the 3D visualization of dynamic events that happened on the biomolecules inside the cellular structures.
•The developed Laguerre-Gaussian vortex angle spectrum reconstruction algorithm can be employed switchable to retrieve regular SIDH images or high-contrast edge enhancement images, and the background ...noise can be well suppressed in reconstructions. To our knowledge, this is the first demonstration of simultaneously perform SIDH edge imaging without any changes about system with incoherent illumination.•Our proposal can be used conveniently for direction-optional non-local edge enhancement with high contrast by adjusting the phase parameter during reconstruction. The proposal has also possessed the capability of adaptive optical aberration correction.•Our proposal has been verified the capability of high-contrast edge enhancement imaging for different depth objects simultaneously. It presents the great potential ability for 3D objects edge enhancement and imaging.
Edge enhancement with incoherent illumination is an important research branch of optical imaging and information processing, which presents valuable potential application in target recognition, biomedical microscopy, optical defects detection, optical localization and so on. However, the incoherent optical imaging and information processing system is linear invariable of light intensity transfer and there is not an accurate correspondence spatial frequency plane of object complex-amplitude, thus it is limited to obtain edge enhancement imaging by spatial filter in incoherent system. We proposed a computational incoherent edge enhancement imaging based on self-interference digital holography (SIDH). SIDH offers the incoherent object complex-value holograms which is consisted of the incoherent superimposing point spread holograms. The phase of the point spread holograms not only code the depth information of corresponding object-point, but also the difference of the two interference beams and the aberration introduced by recording scheme. The characteristics of incoherent self-interference hologram are employed to utilize edge enhancements and adaptive aberration correction during reconstruction, thus the Laguerre-Gaussian vortex angle spectrum algorithm of SIDH hologram are modified and developed, simultaneous regulating both amplitude and phase in the reconstruction process. Both experimental results demonstrate our method exhibits better performances for edge extraction, background noise can be well suppressed, edge becomes sharper and high contrast. The proposal has also been verified that it can be used for direction-optional edge enhancement, edge enhancement with adaptive aberration correction and edge enhancement imaging of different depth objects simultaneously.
Optical aberrations introduced by sample or system elements usually degrade the image quality of a microscopic imaging system. Computational adaptive optics has unique advantages for 3D biological ...imaging since neither bulky wavefront sensors nor complicated indirect wavefront sensing procedures are required. In this paper, a stochastic parallel gradient descent computational adaptive optics method is proposed for high-efficiency aberration correction in the fluorescent incoherent digital holographic microscope. The proposed algorithm possesses the advantage of parallelly estimating various aberrations with fast convergence during the iteration; thus, the wavefront aberration is corrected quickly, and the original object image is retrieved accurately. Owing to its high-efficiency adaptive optimization, the proposed method exhibits better performances for a 3D sample with complex and anisotropic optical aberration. The proposed method can be a powerful tool for the visualization of dynamic events that happen inside cells or thick tissues.
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