A new recursive augmented Lagrangian (AL) algorithm is presented for the module and phase reconstruction of a 3D wave eld from intensity-only measurements on two or more sensor planes at different axial positions. The wave eld reconstruction is framed as a constrained nonlinear optimization problem allowing to involve prior information on a wave eld of interest. The main goal is to design the a...

We propose a method of wavelength multiplexing based on a modified Gerchberg-Saxton algorithm (MGSA) and a cascaded phase modulation scheme in the Fresnel transform domain to reduce the cross talk in the multiple-image-encryption framework. First, each plain image is encoded to a complex function by using the MGSA. Next, the phase components of the created complex functions are multiplexed with...

Even so-called “complete” ultrashort laser pulse-measurement techniques actually have ambiguities and so are not truly complete. In particular, the spectral-interferometry technique called scanning SEA TADPOLE measures the “complete” spatiotemporal intensity and phase of arbitrary ultrashort pulses (using a previously characterized spatially uniform reference pulse), but the difficulty of maint...

A new phasing algorithm has been used to determine the phases of diffuse elastic X-ray scattering from a non-periodic array of gold balls of 50 nm diameter. Two-dimensional real-space images, showing the charge-density distribution of the balls, have been reconstructed at 50 nm resolution from transmission diffraction patterns recorded at 550 eV energy. The reconstructed image fits well with a ...

A variational approach to reconstruction of phase and amplitude of a complex-valued object from Poissonian intensity observations is developed. The observation model corresponds to the typical optical setups with a phase modulation of wavefronts. The transform domain sparsity is applied for the amplitude and phase modeling. It is demonstrated that this modeling results in the essential advantag...

Iterative algorithms for phase retrieval from intensity data are compared to gradient search methods. Both the problem of phase retrieval from two intensity measurements (in electron microscopy or wave front sensing) and the problem of phase retrieval from a single intensity measurement plus a non-negativity constraint (in astronomy) are considered, with emphasis on the latter. It is shown that...

In this paper, we present a simple method to almost quadruple the spatial resolution of aliased images. From a set of four low resolution, undersampled and shifted images, a new image is constructed with almost twice the resolution in each dimension. The resulting image is aliasing-free. A small aliasing-free part of the frequency domain of the images is used to compute the exact subpixel shift...

The quality of electron bunches accelerated by laser wakefields is highly dependant on the temporal and spatial features driver. Analysis experiments performed at APOLLON PW-class facility shows that instabilities focal spot, such as shot-to-shot pointing fluctuations or asymmetry transverse fluence, lead to charge energy degradation bunch. It shown PIC simulations can reproduce experimental re...