Low-field MR Imaging Using a Nonuniform Fast Fourier Transform

Low-field Magnetic Resonance Imaging (LF MRI) is a cheap and safe technique to visualise the internal structure of the human body. Unlike other imaging techniques, Magnetic Resonance Imaging does not use ionising radiation to generate the images. Instead, it uses magnetic fields and radio waves which are nonthreatening to the health. The LF MRI...

3-D Short-Range Imaging with Irregular MIMO Arrays Using NUFFT-Based Range Migration Algorithm

3-D imaging with irregular planar multiple-input-multiple-output (MIMO) arrays is discussed. Due to signal acquisition on irregular spatial sampling grids by using these antenna arrays, the fast Fourier transform (FFT)-based imaging algorithms cannot readily be used for image formation. To avoid the application of computationally intensive...

NUFFT-Based Range Migration for 3-D Imaging with Irregular Planar Array

In this paper, a Nonuniform fast Fourier transform (NUFFT)-based range migration algorithm (RMA) is proposed for three-dimensional (3-D) imaging with irregular planar arrays. The proposed imaging algorithm takes advantage of NUFFT to reconstruct the signal spectra in the wavenumber domain, which overcomes the constraint of irregular spatial...

Efficient Implementation of GPR Data Inversion in Case of Spatially Varying Antenna Polarizations

Ground penetrating radar imaging from the data acquired with arbitrarily oriented dipole-like antennas is considered. To take into account variations of antenna orientations resulting in spatial rotation of antenna radiation patterns and polarizations of transmitted fields, the full-wave method that accounts for the near-, intermediate-, and...

A fast algorithm for computing and correcting the CTF for tilted, thick specimens in TEM

Today, the resolution in phase-contrast cryo-electron tomography is for a significant part limited by the contrast transfer function (CTF) of the microscope. The CTF is a function of defocus and thus varies spatially as a result of the tilting of the specimen and the finite specimen thickness. Models that include spatial dependencies have not...