Structured illumination microscopy (SIM), as one of the mainstream super-resolution optical microscopy imaging techniques, takes the advantages of fast imaging because of wide-field illumination, which is suitable to the multi-color live cell imaging. However, multi-color imaging measures each spectral image separately, so the imaging speed of is limited. In addition, the spatial-resolution improvement of SIM depends on the modulation frequency of structured pattern. To further improve the imaging resolution, we use a spectral imaging method, i.e., passive ghost imaging, in SIM. Simulation results show that the proposed method has superiority in super-resolution, imaging speed and imaging quality than traditional multi-color imaging and multi-color SIM imaging.
SignificanceDouble-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.AimWe 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.ApproachThe conventional DH-PSF method was modified to accommodate the scanning strategy combined with a deconvolution algorithm. The localization of a fluorescent microsphere is determined by the center of the corresponding double spot, and the image is reconstructed from the scanned data by deconvoluting the DH-PSF.ResultsThe resolution, i.e., the localization accuracy, was calibrated to 13 nm in the transverse plane and 51 nm in the axial direction. Penetration thickness could reach an optical thickness (OT) of 5. Proof-of-concept imaging and the 3D localization of fluorescent microspheres through an eggshell membrane and an inner epidermal membrane of an onion are presented to demonstrate the super-resolution and optical sectioning capabilities.ConclusionsModified DH-PSF microscopy can image and localize targets buried in scattering media using super-resolution. Combining fluorescent dyes, nanoparticles, and quantum dots, among other fluorescent probes, the proposed method may provide a simple solution for visualizing deeper and clearer in/through scattering media, making in situ super-resolution microscopy possible for various demanding applications.
Ghost imaging LIDAR is a new system of gaze imaging radar with high detection sensitivity, super-resolution and better anti-interference performance, but the relative motion between the radar system and the target will make the imaging degenerate. This paper proposes a single-target localization in the field of view by weighting the correlation intensity of rough target images. In a simple background environment, the absolute coordinates of the low-velocity small-size target in the field of view can be obtained. And the reference arm speckles will be compensated in the opposite direction by the translation according to the trajectory obtained by the positioning. An accurate image will be obtained by superimposing many rough images eventually. The proposed correlation intensity weighted positioning, tracking and imaging method has been verified by simulation to be able to locate and image targets in the field of view well.
Double-helix point spread function (DH-PSF), which can convert the axial position of an object into double-spot rotation, is widely used in single-molecule localization microscopy due to its excellent axial localization ability. However, the current single-molecule localization microscopy techniques based on the DH-PSF are mostly applied in non-scattering or weak scattering environments, and are only applicable to sparse objects. In this paper, we study the three-dimensional positioning and imaging through scattering media based on the DH-PSF. The image of the object can be reconstructed from the recorded speckle pattern via speckle autocorrelation and phase retrieval techniques, and the three-dimensional coordinate information of the object can be obtained by the rotation angle and the center of the double spots modulated by the DH-PSF. The positioning accuracy in axial direction for non-sparse objects in simulation is better than 10μm, which is greatly improved compared with our previous work (Journal of Optics, 2021, 23(2):025602 (5pp)). This method has many potential applications in acquiring dynamical information of the micro-object motion.
By combing the technique of coherent detection with ghost imaging, we establish an experimental system for pulse-compression ghost imaging via coherent detection. The results have experimentally demonstrated for the first time the feasibility of ghost imaging via coherent detection. More importantly, it shows that even when echo power is only 5 pW, which is lower than three orders of magnitude compared with previous ghost imaging via photon intensity detection, an image with a spatial resolution of 0.8 mm can be obtained for the proposed method.
Speckle autocorrelation based on optical memory effect is an interesting and important method to realize scattering imaging. However, the effective detection range is limited by the radiation phenomenon of the speckle field when there is a wide spectral illumination. In this paper, by utilizing the response of point spread function (PSF) to image distance (the distance between the detector plane and the scattering medium), we propose a method to improve the imaging quality under wide spectral illumination. PSF is sensitive to the image distance, as the distance between the detection plane and reference plane increases, the correlation coefficient between their PSFs will decreases. Superposing the autocorrelations of speckle patterns under different image distances can suppress the statistical noise, and thus improve the reconstruction quality. This method reduces the dependence on light source power and effective detection range, having certain prospect in seeing through natural turbid media.
KEYWORDS: Super resolution, Diode pumped solid state lasers, Reconstruction algorithms, Optical imaging, Signal to noise ratio, Signal processing, Diffraction, Imaging systems, Fourier transforms, Quantum physics
Sparsity constraint is a priori knowledge of the signal, which means that in some properly chosen basis only a small percentage of the signal components is nonzero. Sparsity constraint has been used in signal and image processing for a long time. Recent publications have shown that by taking advantage of the Sparsity constraint of the object, super-resolution beyond the diffraction limit could be realized. In this paper we present the quantum limits of super-resolution for the sparse objects. The key idea of our paper is to use the discrete prolate spheroidal sequences (DPSS) as the sensing basis. We demonstrate both analytically and numerically that this sensing basis gives superior performance over the Fourier basis conventionally used for sensing of sparse signals. The explanation of this phenomenon is in the fact that the DPSS are the eigenfunctions of the optical imaging system while the Fourier basis are not. We investigate the role of the quantum fluctuations of the light illuminating the object, in the performance of reconstruction algorithm. This analysis allows us to formulate the criteria for stable reconstruction of sparse objects with super-resolution.
Ghost imaging has emerged a decade ago as a new imaging technique. Its feature is the image will appear on the optical
path, which never passes through the object actually. In this paper, we will give an overview of quantum imaging,
include the experiments with two-photon entanglement state source generated by spontaneous parametric down
conversion, as well as with pseudo-thermal light. Then we will show our ghost imaging experiment scheme with the
pseudo-thermal light source. We obtain the pseudo-thermal source by using a XY Phase Series Spatial Light Modulator
(supplied by BNS company) to modulate the laser light. This spatial light modulator changes the phase of the output light
field by controlling the loading element on every pixel.
A theoretical analysis of the x-ray phase imaging in the method of in-line holography setup with a finite size source is presented. Based on the transport of intensity equation (TIE) with a point source, we given an algorithm to quantitatively restore the phase from x-ray phase imaging with an incoherent finite size source. We show that the image intensity is a convolution of the source intensity distribution and the intensity got from the x-ray phase imaging with a point source. The algorithm needs the intensity distribution at the source plane, the plane just after the object and the image plane. Performing deconvolution and solving the TIE, the phase can be retrieved. Analytical investigation of a simple model suggests that our method is mainly applicable to the differential phase contrast case. Numerical examples are also presented.
Laser plasma interactions, plasma's hydrodynamics, and x-ray emissions in half-cylindrical target have been studied. It is found that this kind of target geometry can converge plasma expanding along the radial direction and form uniform flat distributions of electron density. Based on the unique characteristics of this kind of target, we suggest it be used for x-ray laser research. We also suggest a new configuration of two laser heating for x-ray lasers.
In this paper, the results of the X-ray laser gain experiments of Li-like K and Ca ions, conducted recently at LF12 Laser Facility of SIOFM with KCl and CaF2 slab targets, will be presented. Also presented will be the space-resolved time history of ASE emission in the Li-like X-ray lasers and the in-situ calibration for the X-ray film used in the experiments.
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