Ultraviolet Laser System Research Articles

Dynamics of H2 elimination from cyclohexadiene

A comprehensive study of the dynamics of H2 elimination from 1,4 and 1,3 cyclohexadiene is reported. Rotational and vibrational quantum state distributions as well as translation energy distributions for the H2 product are measured. State specific detection of H2 is accomplished with a transform limited vacuum ultraviolet–extreme ultraviolet laser system via (1+1) resonance enhanced multiphoton ionization (REMPI). Rate constants for the H2 elimination and 1,4 to 1,3 isomerization reactions are derived. A (v,J) correlation for H2 with v∥J primarily is observed from anisotropy in the Doppler profiles. A clear picture of the transition state configuration of 1,4 cyclohexadiene is provided from the information obtained.

A ring-cavity for a quadrupled Nd-Yag lasera

A new high-powered ultraviolet laser system is proposed. The system doubles the infrared light from a Nd-Yag laser mode-locked at 100 MHz, injects this light into a storage-ring cavity to accumulate a high power in the visible and then doubles this into the ultraviolet at 2600 A. The power levels anticipated at this wavelength are much larger than those of commercially available c.w. lasers. The new system can have a far-reaching impact in basic research and, even more so, in a great many industrial applications.

Arthroscopic cartilage debridement by excimer laser in chondromalacia of the knee joint

A new operative technique in arthroscopic treatment of chondromalacia using ultraviolet laser systems is introduced. The postoperative results are evaluated in a prospective and randomized clinical trial. One hundred and forty patients stage II or III chondromalacia according to Outerbridge were randomly assigned to arthroscopic operation using either laser or mechanical instruments. After a 6-month follow-up period the clinical results were compared, guided by a specially designed modification of the Lysholm scoring scale. In the short-term follow-up laser surgery gave superior results in regard to reducing pain (P less than 0.05) and leading to a lower incidence of reactive synovitis (P less than 0.01). No difference was found in respect of disability and functional impairment. Our results lead to the conclusion that arthroscopic laser application seems to be a successful procedure in the treatment of degenerative cartilage disorders, providing precise ablation of tissue without significant thermal damage to the remaining cartilage.

Dynamics of H2 elimination from 1,4-cyclohexadiene

The dynamics of H2 elimination from 1,4-cyclohexadiene (CHDN), dissociated with 212 nm light, have been studied by state specific probing of the H2 product via (1+1) REMPI using a transform limited vacuum ultraviolet laser system. The quantum state distributions, the translational energy distribution and the Doppler profiles were measured giving a ‘‘rotational temperature’’ of ≂1600 K, a ‘‘vibrational temperature’’ of ≂4000 K, and a translational energy of ≂30 kcal/mol for H2. Anisotropy in the Doppler profiles indicates that the H2’s velocity vector is aligned parallel to its rotational angular momentum vector.

Comparative photon statistics of several ultraviolet laser systems determined by transient two-photon absorption

The photon statistics of several different laser systems operating at 226 nm are probed by measuring absolutely the fluorescence following two-photon absorption in atomic oxygen. The integrated fluorescence, obtained by scanning the laser frequency through the two-photon resonance, is theoretically shown to be proportional to G(2) (0) σ0(2). The second-order intensity-correlation function at time zero, G(2)(0), characterizes the laser, and σ0(2) is a fundamental atomic property. Measurement of the integrated fluorescence permits determination of the relative value of G(2) (0) for each laser. The assumption that G(2)(0) = 1 for one of the lasers, a single-frequency source, allows G(2)(0) for the other lasers to be placed on an absolute scale. The values thereby obtained range from 0.8 ± 0.2 to 3.2 ± 0.4. Different values are obtained when the radiation is generated by frequency mixing or Raman shifting of the same frequency-doubled visible dye laser, suggesting that frequency-conversion processes have a significant effect on G(2)(0).

Output Optics for Aurora: Beam Separation, Pulse Stacking, and Target Focusing

An end-to-end technology demonstration prototype for large-scale ultraviolet laser systems of interest for short wavelength, inertial confinement fusion (ICF) investigations. The system is designed to employ optical angular multiplexing and serial amplification by electron-beam-driven KrF laser amplifiers to deliver to ICF targets a stack of pulses with a duration of 5 ns containing several kilojoules at a wavelength of 248 nm. The optical system has been designed in two phases. The first phase carries only through the amplifier train and does not include a target chamber or any demultiplexing. During first-phase design, the system was conceived of as only an amplifier demonstration and not as an end-to-end system demonstration. The design concept for second-phase optics that provides demultiplexing and carries the laser light to target is presented.

Aurora Multikilojoule KrF Laser System Prototype for Inertial Confinement Fusion

Aurora is the Los Alamos National Laboratory short-pulse, high-power, KrF laser system. It serves as an end-to-end technology demonstration for large-scale ultraviolet laser systems of interest for...

An overview of Aurora: a multi-kilojoule KrF laser system for inertial confinement fusion

Aurora is a short-pulse high-power krypton-fluoride laser system that serves as an end-to-end technology demonstration prototype for large-scale ultraviolet laser systems of interest for short wavelength inertial confinement fusion (ICF) studies. The system is designed to employ optical angular multiplexing and serial amplification by electron-beam-driven KrF laser amplifiers to deliver 248 nm, 5-ns duration multi-kilojoule laser pulses to ICF targets using a beam train of approximately 1 km in length.In this paper, we will discuss the goals for the system and summarize the design features of the major system components: front-end lasers, amplifier train, optical train, and the alignment and controls systems.

Tunable near ultraviolet laser system from a frequency doubled alexandrite laser

A laser system which is capable of producing radiation tunable over the region from approximately 0.36-0.40 \mu m is described. The laser produces in excess of 5.0 mJ per pulse in a \sim0.1 \mu s pulse length.

Possibility of construction of collisional VUV lasers utilizing alkali metal vapors

Vacuum ultraviolet (VUV) laser systems for the 60–80 nm range are proposed on the basis of utilization of collisional energy transfer from metastable levels of rare gases to alkali metal atoms and excitation of the latter to long-lived quartet autoionizing states. Either the atoms are transferred from these states to upper active levels by a pulse of strong laser radiation or stimulated Raman scattering is accompanied by the emission of VUV photons.

CIF and F 2: two new ultra-violet laser systems

During the past few years the development of new lasers has concentrated on species which emit in the visible to the far ultra-violet spectral range. This paper deals with a new class of potential high power lasers, the halogens and the interhalogens. These molecules have attracted considerable interest because of the high fluorescence yield exhibited by some of them. More recently the F 2 laser was successfully excited by the TEA discharge configuration as applied in rare gas halides lasers. During experiments to identify the exact pumping reaction, the first interhalogen laser CIF was found. The emission is centred around 284 mm.

A tunable visible and ultraviolet laser on S2 (B3Σu−–X3Σg−)

Laser action has been achieved on the B3Σu−–X3Σg− transition of S2 by optical pumping with a frequency-doubled dye laser and a nitrogen laser. The observed lasing is line tunable from 365 to 570 nm. The S2 molecule is a promising candidate for an efficient scalable ultraviolet laser system.

The interaction of the ultra-violet and near infra-red laser systems of molecular nitrogen

The interaction between the nitrogen 1st and 2nd + ve laser systems is analysed when the systems are made to oscillate simultaneously.