Abstract-To measure the phase of signal with very high working frequency such as THz, and optics band is still a challenging problem. In this paper, based on the relationship between radiating current and measured intensity of electrical field a novel phase retrieval algorithm has been developed. As opposed to the existing approaches of phase retrieval where usually the Fourier coefficients of measured data will be firstly reconstructed, the proposed approach is to reconstruct the so-called radiating currents, with more physical meaning than the former. It has a much smaller number of freedoms of radiating current than that of measurements, which means that the obtained equations are over-determined. Thus one can efficiently model the intensity of measured electric field via the radiating part, and reconstruct it quickly and stably. The novelty is that this physical consideration 1) leads to efficiently avoiding false solutions due to the ill-posedness of phase retrieval problem, and 2) offers a good initial guess for inverse scattering based imaging algorithm. Importantly, a closed-form formulation of phase retrieve also has been derived when the intensity of incident wave is much stronger than one of the scattered wave, for example, for the weak scattering objects. Finally, several numerical experiments are provided to show the high performance of proposed algorithm.

Lake sediment as a potential sink and source of contaminants, it is still relatively less known about than the ecological heavy metals risk in an arid region saline lake. The goal of this study aimed to reveal concentrations of Cr, Ni, Cu, Zn, As, Cd and Pb in saline lake sediments, and to evaluate its pollution status, potential ecological risks and sources for sediments in the study area. Here we analyzed 13, 15 and 8 sediment samples from Ebinur Lake, Barkol Lake and Dabancheng Saline Lake, respectively. The mean concentrations of Cr (74.55 mg kg -1 ), Cu (27.75 mg kg -1 ), Zn (73.00 mg kg -1 ), As (37.65 mg kg -1 ), and Cd (0.31 mg kg -1 ) were higher than the background values of the Xinjiang, and the mean enrichment factor (EF) and geo-accumulation index (I geo ) showed that As (EF = 7.44, I geo = 1.35) and Cd (EF = 11.09, I geo = 0.50) in saline lake sediments were moderate and partially seriously contaminated, while Cr, Zn and Cu caused moderate pollution. The potential ecological (RI) seven heavy metals risk assessment degree decreased in the following sequence: Cd (78.77)>As (32.22)>Cu (5.22)>Ni (4.28)>Pb (3.27)>Cr (3.21)>Zn (1.07), and the RI for Cd exhibited moderate to considerable risk. The As and Cd were the major risk factors among the seven metals. Correlation analysis, principal component analysis and hierarchical cluster analysis deduced that Cu, Ni, and Zn originate mainly from a geological background, while As, Cd and Cr were mainly from anthropogenic sources. Anthropogenic activities lead to heavy metals enrichment in sediments, while As and Cd are the primary contaminants in saline lake sediments in northwestern China.

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