نتایج جستجو برای: laser beam effect
تعداد نتایج: 1894333 فیلتر نتایج به سال:
Laser filaments appear spontaneously during the propagation of intense ultrashort laser pulses with a power exceeding a critical value Pcr (Pcr = 5 GW at 800 nm in air) [1]. The intense beam tends to collapse due to the optical Kerr self-focusing effect until the intensity is high enough to ionize the medium, giving rise to a defocusing plasma. Thereafter, a dynamic competition between these tw...
Experimental investigations on an e-beam sustained near infrared Ar :Xe laser have been carried out to determine the intrinsic efficiency at optimized conditions. A parametric study at different sustainer currents reveals a maximum output energy depending on current density. Up to 8 bar the optimized laser output power per unit volume increases linearly with 1.1 M W / l b a r . Intrinsic effici...
If authors will state in their covering communications whether they expect their institutions to pay the publication charge, publication time should be shortened (for those who do). Photorefractive materials are now widely studied for their large nonlinear optical properties. Large gain values in two-beam coupling or degenerate four-wave mixing experiments are easily available using a low-power...
A nonlinear acoustic effect is a sensitive tool to detect a micro-scale crack or early stage of cracking during the fatigue process. The damage produces a nonlinear stress-strain relationship, and the nonlinearity can be measured by a higher harmonic component in the frequency domain. The greater the damage, the larger the level of a nonlinearity, which can be used for the diagnosis of micro-cr...
A new Raman spectrometer has been developed that can produce a complete high-resolution gas-phase vibrational spectrum during the time period of a single laser pulse. Conventional gas-phase Raman spectroscopy uses a single narrow-band laser to produce signals that are weak, requiring relatively long collection times. This spectrometer uses a degenerate OPO as a broad-band source that covers a c...
An ABCD beam-propagation method was used to build a first-order mathematical model of a thermal lens effect from a near-infrared laser beam in water and ocular media. The model was found to fit experimental z-scan data best when the thermo-optic coefficient dn/dT of liquid water at 292 K was -4.46x10(-5) K(-1). The physiological parameters of the human eye were simulated in a simple eye model u...
Laser direct processing of glass has been challenging due to the brittle nature and poor heat transfer characteristics of the material. With the advancement of ultrashort pulse lasers, laser direct machining of glass with smooth surface and free of microcracks has become a potential manufacturing technique in microfabrication of optical devices. In this paper, machining of microgrooves on fused...
The very bright electron beam required for an x-ray freeelectron laser (FEL), such as the LCLS, is susceptible to a microbunching instability in the magnetic bunch compressors, prior to the FEL undulator. The uncorrelated electron energy spread in the LCLS can be increased by an order of magnitude to provide strong Landau damping against the instability without degrading the FEL performance. To...
High-order harmonics have been generated by the use of an annular laser beam. The nonlinearity of harmonic production and the shorter wavelengths involved cause the harmonics to emerge strongly peaked on the laser axis. Thus the harmonics emerge from the focus inside the missing portion of the laser beam. This permits the laser to be blocked by an aperture that passes the harmonics.
Randomly distributed lattice point defects such as supersaturated vacancies (SVs) and Frenkel-pairs (FPs, an interstitial and a vacancy) can be simultaneously introduced into the crystal by energetic beam irradiation in outer space and/or nuclear reactors, but their behavior has not been fully understood. Using a high-voltage electron microscope equipped with a laser (laser-HVEM), we show the s...
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