Phase-coded modulation 3D ghost imaging

The optical transfer function (OTF), which correspond to the frequency domain, is of fundamental importance in characterizing imaging ability in optical imaging systems. By using the Collins formula and the optical transfer matrix theory, a simple and unified analytical expression of OTF is presented in any ghost imaging (GI) system. By comparing the spectrum distribution of OTF between different GI systems, one can predict which imaging system can provide better imaging quality when the same imaging object is used. Theoretical and experimental results are also implemented to verify our results.

Validation and reproducibility of a high-resolution three-dimensional facial imaging system

Digit classification of ghost imaging based on similarity measures

Quantum ghost imaging uses photon pairs produced from parametric downconversion to enable an alternative method of image acquisition. Information from either one of the photons does not yield an image, but an image can be obtained by harnessing the correlations between them. Here we present an examination of the resolution limits of such ghost imaging systems. In both conventional imaging and quantum ghost imaging the resolution of the image is limited by the point-spread function of the optics associated with the spatially resolving detector. However, whereas in conventional imaging systems the resolution is limited only by this point spread function, in ghost imaging we show that the resolution can be further degraded by reducing the strength of the spatial correlations inherent in the downconversion process.

Ethics review and clinical trials

In the ghost imaging system based on the multidimensional vector matrix Walsh transform, the Walsh speckle pattern is used to continuously sample the moving target object, so there is a certain correlation and complementary detail information between multiple frames in the ghost imaging video. In our previous research, we broke through the inherent limitations of the digital micromirror device refresh rate on ghost imaging systems, allowing us to reconstruct more detailed frames. Therefore, by utilizing the correlation between these detailed frames in the time and space domains, we can improve the comfort of ghost imaging videos from the perspective of improving the single-frame quality of ghost imaging videos. To further improve multi-frame quality by utilizing more detailed frames in ghost imaging videos, this paper proposes a ghost imaging video algorithm based on the multidimensional vector matrix Walsh transform of bidirectional N-aligned fusion frames. Combining deep learning with computational ghost imaging, utilizing a bidirectional N-alignment algorithm and a deep learning neural network framework for target frame integration. The ghost imaging videos obtained from previous research can be improved in terms of noise, motion blur, and single-frame detail richness to enhance the imaging quality of the target frame. This paper constructs an encoding module and a corresponding feature fusion module suitable for multidimensional vector Walsh transform ghost imaging from the perspective of network width and feature multi-branch extraction based on GoogleNet Inception V3. A loss function suitable for four-dimensional vector matrix Walsh transform ghost imaging has been defined, which can better eliminate the noise and distortion caused by Walsh speckle sampling. After comparing the experimental results of moving objects, the results show that the algorithm proposed in this paper has significantly improved structural similarity, blur index, noise index, and other aspects compared to existing ghost imaging video optimization methods. The similarity angle of the NRSS structure has increased by 18.58% compared to the original reconstructed image, the blur parameter has increased by 31.9%, and the noise parameter has risen by 9.22%.

We demonstrate a novel ghost imaging (GI) scheme based on one single-photon-counting detector with subsequent photon statistics analysis. The key idea is that instead of measuring correlations between the object and reference beams such as in standard GI schemes, the light of the two beams is superimposed. The photon statistics analysis of this mixed light allows us to determine the photon number distribution as well as to calculate the central second-order correlation coefficient. The image information is obtained as a function of the spatial resolution of the reference beam. The performance of this photon-statistics-based GI system with one single detector (PS-GI) is investigated in terms of visibility and resolution. Finally, the knowledge of the complete photon statistics allows easy access to higher correlation coefficients such that we are able to perform here third- and fourth-order GI. The PS-GI concept can be seen as a complement to already existing GI technologies thus enabling a broader dissemination of GI as a superior metrology technique, paving the road for new applications in particular with advanced photon counting detectors.

Sunlight background noise significantly hinders the operation of ghost imaging systems, posing a considerable challenge for target imaging under daytime sunlight conditions. This paper introduces a method to eliminate sunlight background noise using a Faraday anomalous dispersion optical filter (FADOF). A ghost imaging system based on FADOF is constructed, and experiments are conducted under strong background noise conditions. The system operates outdoors in direct sunlight, utilizing sunlight introduction system to introduce light into the detection path, directly reaching the detection end of the system. In this real sunlight noise condition, the ghost imaging system using FADOF filtering achieved nearly continuous and stable imaging throughout three summer days, contrasting with a system using a 10 nm filter that only functions properly after sunset. The research findings indicate that FADOF effectively enhances the ghost imaging system's resistance to background light noise, enabling continuous operation under conditions of strong background noise throughout the day.

Equipment requirement, quality of reconstructed image, and reconstruction time are important factors in the realization of thermal-light ghost imaging system. In this paper, we propose a new ghost imaging scheme with multiple speckle patterns, named multiple speckle patterns differential compressive ghost imaging scheme. In this scheme, the high temporal resolution requirements for detectors is reduced by continuously detecting multiple independent speckle patterns. We eliminate the background and other noises in ghost imaging system by using differential ghost imaging method. And the reconstruction time is effectively reduced simultaneously to improve the reconstructed image quality by introducing the compressive sensing techniques. Numerical results show that for the two-level grayscale “N” image, the mean square error, in using the proposed scheme with 8000 measurements, is reduced by 96.9%, and the peak signal to noise ratio has improved by 15.1 dB, in comparison with those using the original multiple speckle patterns ghost imaging scheme with 35000 measurements. For the eight-level grayscale “Pepper” image, the peak signal to noise ratio is enhanced by 11.4 dB. The proposed scheme also can decrease the requirements of detection equipment to improve the image quality, and reduce the reconstruction time. Therefore, it may have a broad application prospect.

Remote-sensing applications within atmospheric scattering environments pose substantial challenges for traditional optical imaging systems owing to photon scattering, signal attenuation, and noise-induced degradation. This paper presents a ghost imaging technique operating in the Fourier domain, integrated with adaptive multistage post-processing enhancement algorithms to improve image reconstruction fidelity in the presence of scattering media. The experimental framework utilizes a digital micromirror device (DMD) to generate structured Fourier basis patterns in the reference arm, while the signal arm traverses controllable scattering media simulated using a precision-positioned ground glass (GG) diffuser. Image reconstruction is achieved through frequency-domain correlation processing employing a three-step phase-shifting algorithm, while reconstructed image degradation is mitigated through a multi-stage enhancement pipeline incorporating adaptive denoising, deblurring, and contrast optimization algorithms. Experimental validation demonstrates that the proposed methodology achieves recognizable image reconstruction using 25% of the Fourier coefficient set under high-scattering conditions, with enhancement algorithms providing up to 30% improvement in peak signal-to-noise ratio (PSNR) relative to unprocessed reconstructions. This investigation reveals fundamental limitations in dense scattering regimes and provides insights into the computational trade-offs inherent in ghost imaging systems under challenging environmental conditions.

Edge detection is an essential procedure in biomedical image processing. Note that several edge detection schemes based on ghost imaging (GI) have been proposed, while a practical application environment is not considered. In this paper, we first investigate the edge detection of target objects inside biological tissue in a GI system. The performances of four edge detection operators are compared in GI through biological tissue when refractive index turbulence is considered. The numerical results demonstrate that the Standard operator performs better in edge extraction regardless of the strength of refractive index fluctuations. Our results may provide potential applications of GI in the field of biomedical imaging.

The principle of equivalence between the imaging properties of scanning and conventional imaging systems has been proven in the past by assuming scalar sources of radiation and isotropic media. We prove here its general validity for optical systems with vector, electromagnetic sources of radiation and any optically nonactive media.

In order to achieve global optimization in conventional optical imaging systems, complex optical design is required to eliminate various aberrations simultaneously. Imaging through scattering media can be achieved by the speckle autocorrelation method based on optical memory effect in a single-shot non-invasive way. By adding a scattering medium to the imaging system, multi-aberrations can be eliminated simultaneously. As an example, in a simple optical imaging system with spatially incoherent illumination, a ground glass plate is placed between the lens and the camera as a scattering medium. Finally, multi-aberrations such as spherical aberration, coma aberration and chromatic aberration are eliminated at the same time. Therefore, scattering media can be used as a tool to optimize optical imaging systems.

We show that the image quality of ghost imaging (GI) can be controlled by the use of shaped incoherent sources. The formula for the point-spread function in the GI system has been derived and is determined by the Fourier transform of the source intensity distribution. Compared with the widely used Gaussian Schell-model source, we find that using a cosine-Gaussian Schell-model source can lead to the degradation of GI quality, while the quality of GI can be increased with a cosh-Gaussian Schell-model source. Even under atmospheric turbulence, the image resolution of GI still can be improved by means of the cosh-Gaussian Schell-model source.

The laser three-dimensional imaging system has the advantages of rich information acquisition and fewer working conditions, which is a hot spot in the research of imaging methods. Pulse ranging laser 3D imaging obtains the relative distance between the imaging system and the target through the photon flight time. Although the distance resolution is usually on the order of centimeters, the working distance range is large, which can meet the working distance range and accuracy of laser 3D imaging at the same time. Demand. The three-dimensional imaging of array detectors such as APD array can significantly improve the three-dimensional imaging performance of the system, but the detector is limited by the area of the photosensitive area, and the energy utilization efficiency is still low. This article combines the requirements of the receiving optical system in the APD array three-dimensional imaging system to improve the energy transmission efficiency. First, it outlines the principle and basic composition of the microlens array to improve the energy transmission efficiency, and then briefly describes the microlens distribution size and focal length. The design constraints of the microlens. Finally, for the two cases of whether the microlens array is used or not, the difference in the efficiency of the receiving optical system is compared and analyzed. The analysis results can provide a certain reference for the design of APD array three-dimensional imaging.