Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Laser beam

Due to the very high intensity of the laser beams and their coherent nature they may be used in a variety of ways where controlled energy is required. Lasers are used commercially for excitation with a specific energy, e.g. in Raman spectroscopy or isotope separation. [Pg.235]

The approximation of Fresnel is scalar approximation. Let u(, r],0-0) be the scalar wave function of the laser beam falling onto the optical element, and u( X,y,Cl) will the be scalar wave function in the plane Z = Cl. Then [3,4]... [Pg.266]

The previous investigations of hard particle transport processes during laser beam dispersing have shown, that the high speed microfocus radioscopy system is a usable arrangement to observe and analyse the movements, velocities and accelerations of particles inside the molten bath. That possibility was, until now, not given by conventional techniques of process... [Pg.546]

The investigations show that the microfocus high speed radioscopy system is suitable for monitoring the hard particle transport during laser beam dispersing. It is possible to observe and analyse the processes inside the molten bath with the presented test equipment. As a consequence a basis for correlation with the results of a simulation is available. [Pg.549]

The authors thank the German Research Community (DFG) for their assistance within their investigation project Beam-Material-Interaction During Laser Beam Machining". [Pg.549]

When directed towards the test piece the laser beam passes through a centre hole in a 45 degree fixed-angle mimor. Between this mirror and the test piece the laser beam and the flourescence follow a common beam path. A photodetector is aimed at the 45 degrees angle mirror and, therefore, looks along the laser in this common beam path, see Fig 3. [Pg.640]

When a laser beam eross a rough surface, the scattered light presents an granular aspect, which is call speckle. [Pg.656]

A diffuser G is illuminated with a He-Ne laser, trough a rectangular aperture A, which limits the illuminated area. A graduated screen is located at the observation plane 110(71, ), located at a distance D from the reference plane n(x,y), and perpendicularly arranged to the incident laser beam. The rotation axis y is also perpendicular to the beam. [Pg.657]

This paper deals with the control of weld depth penetration for cylinders in gold-nickel alloy and tantalum. After introducing the experimental set-up and the samples description, the study and the optimization of the testing are presented for single-sided measurements either in a pulse-echo configuration or when the pump and the probe laser beams are shifted (influence of a thermal phenomenon), and for different kind of laser impact (a line or a circular spot). First, the ultrasonic system is used to detect and to size a flat bottom hole in an aluminium plate. Indeed, when the width of the hole is reduced, its shape is nearly similar to the one of a slot. Then, the optimization is accomplished for... [Pg.693]

Fig. IV-11. A laser beam incident on the liquid surface at angle B is scattered by angle AS by surface thermal waves of wave vector k. (From Ref. 132.)... Fig. IV-11. A laser beam incident on the liquid surface at angle B is scattered by angle AS by surface thermal waves of wave vector k. (From Ref. 132.)...
LIF Laser-induced fluorescence Incident laser beam excites Excited-state processes ... [Pg.317]

LID) see Ref. 139. In this last method, a small area, about 0.03 cm radius, is depleted by a laser beam, and the number of adatoms, N(t), that have diffused back is found as a function of time. From Pick s second law of diffusion ... [Pg.710]

Surfaces are investigated with surface-sensitive teclmiques in order to elucidate fiindamental infonnation. The approach most often used is to employ a variety of techniques to investigate a particular materials system. As each teclmique provides only a limited amount of infonnation, results from many teclmiques must be correlated in order to obtain a comprehensive understanding of surface properties. In section A 1.7.5. methods for the experimental analysis of surfaces in vacuum are outlined. Note that the interactions of various kinds of particles with surfaces are a critical component of these teclmiques. In addition, one of the more mteresting aspects of surface science is to use the tools available, such as electron, ion or laser beams, or even the tip of a scaiming probe instrument, to modify a surface at the atomic scale. The physics of the interactions of particles with surfaces and the kinds of modifications that can be made to surfaces are an integral part of this section. [Pg.284]

While a laser beam can be used for traditional absorption spectroscopy by measuring / and 7q, the strength of laser spectroscopy lies in more specialized experiments which often do not lend themselves to such measurements. Other techniques are connnonly used to detect the absorption of light from the laser beam. A coimnon one is to observe fluorescence excited by the laser. The total fluorescence produced is nonnally proportional to the amount of light absorbed. It can be used as a measurement of concentration to detect species present in extremely small amounts. Or a measurement of the fluorescence intensity as the laser frequency is scaimed can give an absorption spectrum. This may allow much higher resolution than is easily obtained with a traditional absorption spectrometer. In other experiments the fluorescence may be dispersed and its spectrum detennined with a traditional spectrometer. In suitable cases this could be the emission from a single electronic-vibrational-rotational level of a molecule and the experimenter can study how the spectrum varies with level. [Pg.1123]

In a typical time-resolved SHG (SFG) experiment using femtosecond to picosecond laser systems, two (tlnee) input laser beams are necessary. The pulse from one of the lasers, usually called the pump laser, induces the... [Pg.1296]

Kogelnik H and LI T 1966 Laser beams and resonators Proc. IEEE 5 88-105... [Pg.1590]

Figure Bl.18.10. Scaimmg microscope in reflection the laser beam is focused on a spot on the object. The reflected light is collected and received by a broad-area sensor. By moving the stage, the object can be scaimed point by point and the corresponding reflection data used to construct the image. Instead of moving the stage, the illuminating laser beam can be used for scaiming. Figure Bl.18.10. Scaimmg microscope in reflection the laser beam is focused on a spot on the object. The reflected light is collected and received by a broad-area sensor. By moving the stage, the object can be scaimed point by point and the corresponding reflection data used to construct the image. Instead of moving the stage, the illuminating laser beam can be used for scaiming.
Detection of cantilever displacement is another important issue in force microscope design. The first AFM instrument used an STM to monitor the movement of the cantilever—an extremely sensitive method. STM detection suffers from the disadvantage, however, that tip or cantilever contamination can affect the instrument s sensitivity, and that the topography of the cantilever may be incorporated into the data. The most coimnon methods in use today are optical, and are based either on the deflection of a laser beam [80], which has been bounced off the rear of the cantilever onto a position-sensitive detector (figme B 1.19.18), or on an interferometric principle [81]. [Pg.1693]

Figure B2.5.11. Schematic set-up of laser-flash photolysis for detecting reaction products with uncertainty-limited energy and time resolution. The excitation CO2 laser pulse LP (broken line) enters the cell from the left, the tunable cw laser beam CW-L (frill line) from the right. A filter cell FZ protects the detector D, which detennines the time-dependent absorbance, from scattered CO2 laser light. The pyroelectric detector PY measures the energy of the CO2 laser pulse and the photon drag detector PD its temporal profile. A complete description can be found in [109]. Figure B2.5.11. Schematic set-up of laser-flash photolysis for detecting reaction products with uncertainty-limited energy and time resolution. The excitation CO2 laser pulse LP (broken line) enters the cell from the left, the tunable cw laser beam CW-L (frill line) from the right. A filter cell FZ protects the detector D, which detennines the time-dependent absorbance, from scattered CO2 laser light. The pyroelectric detector PY measures the energy of the CO2 laser pulse and the photon drag detector PD its temporal profile. A complete description can be found in [109].

See other pages where Laser beam is mentioned: [Pg.516]    [Pg.542]    [Pg.543]    [Pg.548]    [Pg.640]    [Pg.640]    [Pg.679]    [Pg.694]    [Pg.695]    [Pg.696]    [Pg.1065]    [Pg.238]    [Pg.218]    [Pg.311]    [Pg.800]    [Pg.805]    [Pg.915]    [Pg.1123]    [Pg.1145]    [Pg.1199]    [Pg.1204]    [Pg.1263]    [Pg.1281]    [Pg.1297]    [Pg.1298]    [Pg.1632]    [Pg.1699]    [Pg.1716]    [Pg.2073]    [Pg.2389]    [Pg.2444]    [Pg.2476]   
See also in sourсe #XX -- [ Pg.224 , Pg.247 ]

See also in sourсe #XX -- [ Pg.218 ]

See also in sourсe #XX -- [ Pg.335 ]




SEARCH



Alkali elements, atomic beam laser

Argon laser beam

Atomic beam laser spectroscopy

Atomic beam, laser spectroscop

Atomic beams laser-resonance spectroscopy

Attenuation of the Laser Beam

Beam of laser

Beam-laser technique

CO2 laser beam

Collinear fast-beam laser

Collinear fast-beam laser spectroscopy

Combination of Molecular Beam Laser Spectroscopy and Mass Spectrometry

Confocal scanning-beam laser

Confocal scanning-beam laser microscopy

Crossed laser-molecular beam studies

Diode lasers beam profile

Double-beam picosecond laser

Double-beam picosecond laser system

Dual-beam laser Doppler

Dye laser beams

Excited states laser beams

Fast beam experiments using laser

Fast beam laser

Fast-beam laser spectroscopy

Hazard laser beam

HeNe laser beam

Incident laser beam

Induced by a Single Ar Laser Beam

Infrared laser beams

Interactions Between Laser Beam and Glass

Ion beam, laser spectroscopy

Laser Beam Machining (LBM)

Laser Beam Steering

Laser Beam Welding (LBW)

Laser Photo-Detachment in Molecular Beams

Laser Spectroscopy in Fast Ion Beams

Laser Spectroscopy in Molecular Beams

Laser Spectroscopy in Supersonic Beams

Laser ablation molecular beam Fourier transform

Laser ablation molecular beam Fourier transform microwave spectroscopy

Laser ablation, molecular beam

Laser ablation, molecular beam spectrometer

Laser beam Light emitting diodes

Laser beam addressing

Laser beam deflection

Laser beam deflection method

Laser beam diameter

Laser beam effects

Laser beam excitation

Laser beam expansion, detection

Laser beam focusing

Laser beam machining

Laser beam melting

Laser beam path

Laser beam processes

Laser beam processes machining

Laser beam processes soldering

Laser beam processes welding

Laser beam profile

Laser beam quality

Laser beam shape

Laser beam soldering

Laser beam, experimental configuration

Laser beam, light intensity, calculation

Laser coherent beam

Laser control electron beam focusing

Laser focusing of an atomic beam

Laser ion beam

Laser microwave spectroscopy atomic beam

Laser-RF Double-Resonance Spectroscopy in Molecular Beams

Laser-ablation molecular-beam Fourier

Laser-beam deflection signal

Laser-beam deflection technique

Laser-probe beam, schematic depiction

Laser/electron beam alloying

Lasers and molecular beams

Lasers beam profile from

Maintenance laser beam

Pinhole , confocal scanning-beam laser

Pinhole , confocal scanning-beam laser microscope

Spectroscopy atomic beam laser, experiments

Spot welding laser beam

Vaporizing laser beam

Welding laser beam

© 2024 chempedia.info