High‐resolution electron microscopy and its applications

Abstract

A review of research on high-resolution electron microscopy (HREM) carried out at the Institute of Physics, the Chinese Academy of Sciences, is presented. Apart from the direct observation of crystal and quasicrystal defects for some alloys, oxides, minerals, etc., and the structure determination for some minute crystals, an approximate image-contrast theory named pseudo-weak-phase object approximation (PWPOA), which shows the image contrast change with crystal thickness, is described. Within the framework of PWPOA, the image contrast of lithium ions in the crystal of R-Li2Ti3O7 has been observed. The usefulness of diffraction analysis techniques such as the direct method and Patterson method in HREM is discussed. Image deconvolution and resolution enhancement for weak-phase objects by use of the direct method are illustrated. In addition, preliminary results of image restoration for thick crystals are given.

A Novel Method for Doppler and DODDOA Jointly Estimation Based on FRFT in Bistatic MIMO Radar System

“…Multiple-Input Multiple-Output (MIMO) system has attracted more and more attention for its ability to enhance system performance [1][2][3][4]. A MIMO radar system consists of both transmit and receive sensors.…”

“…Most existing algorithms are divided into two categories. One ignores Doppler frequency and only estimated DOA and DOD as shown in [2][3][4]. The other estimates not only DOA and DOD but also timeinvariant Doppler frequency.…”