In the laser deposition of single crystal and directionally-solidified superalloys, it is desired to form laser deposits with high volume fractions of columnar grains by suppressing the columnar-to-equiaxed transition efficiently. In this paper, the influence of beam profile (circular and square shapes) and cooling conditions (natural cooling and forced cooling) on the geometric morphology and ...

Applications based on the propagation of high power laser radiation through the atmosphere are limited in range and effect, due to weather dependent beam wandering, beam deterioration, and scattering processes. Security and defense related application examples are countermeasures against hostile projectiles and the powering of satellites and aircrafts. For an examination of the correlations bet...

We describe a simple experiment that demonstrates one-dimensional laser cooling in a sealed vapor cell. A velocity selective optical pumping scheme was first used to define a collimated beam of atoms within the cell. A particular velocity group of atoms was labeled by optical pumping with one laser and detected by absorption with a second laser. Transverse cooling of this velocity group, which ...

We report on the world’s first experiment of a parallel profile scan of the hydrogen ion (H) beam using a laser wire system. The system was developed at the superconducting linac (SCL) of the Spallation Neutron Source (SNS) accelerator complex. The laser wire profile scanner is based on a photo-detachment process and therefore can be conducted on an operational H beam in a nonintrusive manner. ...

The study of target injection, detection, measurement of laser focal point, and laser beam steering have started under co-research in Japan. The smooth-bore gas gun is developed for accurate injection. The applications of divergent laser beam and Arago spot are described for accurate measurement of target position and laser focal point. Magnetic lens for target trajectory adjustment by centerin...

We report a method for characterizing the focussing laser beam exiting the objective in a laser scanning microscope. This method provides the size of the optical focus, the divergence of the beam, the ellipticity and the astigmatism. We use a microscopic-scale knife edge in the form of a simple transmission electron microscopy grid attached to a glass microscope slide, and a light-collecting op...

As the turbine industries need to manufacture turbine blades made of martensitic stainless steel AISI 420 with high toughness and wear resistance, local laser hardening has become more and more important. In this research, surface of the samples was initially hardened by high-power pulsed laser beam; then, optimum parameters of hardening were calculated and wear resistance of surface hardened s...

background: laser-tissue interaction on low-level laser therapy (lllt) has widespread medical applications (e.g., improved wound healing). the tensile strength of radiated tissue by lllt is known to be increased mainly because of cross collagen bands developed after radiation. objective: in this work, we studied the instantaneous effect of radiation of polarized laser beam on the viscoelastic t...

Copropagation of a laser pulse and a relativistic electron beam in a corrugated plasma channel has been proposed for the direct laser acceleration of electrons [Palastro, Phys. Rev. E 77, 036405 (2008)]. The corrugated plasma channel allows for the guiding of laser pulses composed of subluminal spatial harmonics. Phase matching between the electron beam and the spatial harmonics results in acce...

In an experimental study of laser sheet bending, a 160W diode laser is used for twodimensional sheet bending of low-carbon steel. The variables investigated include metal sheet thickness, laser scan speed, laser power, laser beam width, and laser scan pass number. Bend surface appearances are also analysed. The laser sheet bend results demonstrate that a 940Nm diode laser is an effective tool f...