Proc. SPIE. 8518, Quantum Communications and Quantum Imaging X
KEYWORDS: Signal to noise ratio, Optical imaging, Diffraction, Super resolution, Imaging systems, Fourier transforms, Signal processing, Quantum physics, Reconstruction algorithms, Diode pumped solid state lasers
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 CaF<SUB>2</SUB> 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.