We demonstrate the use of neareld scanning optical microscopy (NSOM) for the measurement of the beam properties of SQW-GRINSCH ridge laser diodes. Using NSOM, we measure the eld intensity in the transverse plane at neareld and as a function distance from the facet. The divergence of the laser beam and the beam waists in vertical and lateral dimensions are directly measured and the astigmatism o...

A nonlinear model of two-beam free-electron laser (FEL) in the absence of slippage is presented. The two beams are assumed to be cold with different energies and the fundamental resonance of the higher energy beam is at the third harmonic of lower energy beam. By using Maxwell’s equations and full Lorentz force equations of motion for the electron beams, coupled differential equations are deriv...

Si Nanowires (NWs) were studied by Raman microspectroscopy. The Raman spectrum of the NWs reveals important thermal effects, which broaden and shift the one phonon Raman bands. The low thermal conductivity of the NWs and the low thermal dissipation are responsible for the temperature enhancement in the NW under the excitation with the laser beam. We have modeled, using finite element methods, t...

Laser forming is a thermal forming process which uses laser beam irradiation to produce the desired final forms. In this article, the effect of temperature gradient across  Al 6061-T6 aluminum sheets on bending angle is studied. Input parameters including laser power, scan velocity, beam diameter, and sheet thickness are the effective process parameters which influence the temperature gradient....

High-precision positioning of laser beams has been a great challenge in industry due to inevitable existence of noise and disturbance. The work presented in this study addresses this problem by employing two different control strategies: Proportional Integral Derivative (PID) control and state feedback control with an observer. The control strategies are intended to stabilize the position of a ...

We report on an experimental method to align a laser beam to a cloud of atoms trapped in a magneto-optical trap (MOT). We show how balanced lock-in detection leads to a very sensitive method to align the laser beam to the atoms in the plane perpendicular to the propagation direction. This provides a very reliable and fast way of aligning laser beams to atoms trapped in a MOT.

We present a new, compact, and practical optical mode converter that efficiently transforms a high-order Hermite-Gaussian (HG) laser beam into a nearly Gaussian beam. The mode converter is based on coherently adding different transverse parts of the high-order mode beam by use of a single planar interferometric element. The method, configuration, and experimental results obtained with a pulsed ...

A practical problem that arises when using acousto-optic modulators sAOMsd to scan the laser frequency is the dependence of the beam diffraction angle on the modulation frequency. Alignment problems with AOM-modulated laser beams can be effectively eliminated by using the AOM in the double-pass configuration, which compensates for beam deflections. On a second pass through the AOM, the beam wit...

LLE Review, Volume 79 149 In the direct-drive approach to inertial confinement fusion (ICF), capsules are irradiated directly by a large number of symmetrically arranged laser beams.1,2 Nonuniformities in the laser irradiation may seed the Rayleigh–Taylor hydrodynamic instability, which degrades target performance;3 therefore, a combination of beam-smoothing techniques is employed to achieve th...

All-optical ideas provide a potential to dramatically cut off the size and cost of x-ray light sources to the university-laboratory scale, with the combination of the laser-plasma accelerator and the laser undulator. However, the large longitudinal energy spread of the electron beam from laser-plasma accelerator may hinder the way to high brightness of these all-optical light sources. In this p...