Spatio-TEmporally REsolved Optical Laser Induced Damage (STEREO LID) technique for material characterization.

A technique for measuring the ablation and laser-induced damage threshold (LIDT) by identifying the temporal onset of damage and location of initiation within the beam profile is demonstrated. This new method, dubbed Spatio-TEmporally REsolved Optical Laser Induced Damage (STEREO LID), is compared to traditional damage tests and its advantages are exemplified.

Determination of defect densities from spatiotemporally resolved optical-laser induced damage measurements.

A procedure is developed to retrieve defect densities of optical coatings and surfaces from spatiotemporally resolved optical-laser induced damage (STEREO-LID) measurements. In STEREO-LID, the temporal onset and location of nanosecond laser damage initiation is measured for each excitation event. The power of STEREO-LID relative to traditional damage tests resulting in damage probabilities is characterized with LID data from Monte Carlo simulations.

Time-dependent absorption of TiO2 optical thin films under pulsed and continuous wave 790 nm laser irradiation.

The time-dependent absorption at 790 nm of TiO2 films prepared by ion-beam sputtering (IBS) and electron-beam evaporation (EBE) was measured. The pump source was a Ti:sapphire oscillator that was operated in CW and pulsed (50 fs) modes. The absorption coefficient of the IBS film under CW illumination was 8  cm-1, independent of time and power.

Femtosecond pulse damage thresholds of dielectric coatings in vacuum.

The dielectric breakdown behavior of dielectric coatings in studied for different ambient gas pressures with femtosecond laser pulses. At 10(-7) Torr, the multiple femtosecond pulse damage threshold, Fm, is about 10% of the single pulse damage fluence F(1) for hafnia and silica films compared to about 65% and 50%, respectively, at 630 Torr. In contrast, the single-pulse damage threshold is pressure independent.

Comparative study of femtosecond and nanosecond laser-induced breakdown spectroscopy of depleted uranium.

We present spectra of depleted uranium metal from laser plasmas generated by nanosecond Nd:YAG (1064 nm) and femtosecond Ti:sapphire (800 nm) laser pulses. The latter pulses produce short-lived and relatively cool plasmas in comparison to the longer pulses, and the spectra of neutral uranium atoms appear immediately after excitation. Evidence for nonequilibrium excitation with femtosecond pulses is found in the dependence of spectral line intensities on the pulse chirp.

Transient mixed-valence character of Re(I)(4)(CO)(12)(4,4'-bpy)(4)Cl(4).

This study addresses, in detail, the orbital nature and the extent of metal-metal communication in the lowest emitting triplet state of Re(4)(CO)(12)(4,4'-bpy)(4)Cl(4) (where 4,4'-bpy = 4,4'-bipyridine) as well as the symmetry of the lowest (3)MLCT manifold in comparison to that of the ground state. All spectral evidence points to (1). a (3)MLCT excited manifold localized between a single Re(I) corner and an adjacent bridging ligand, (2).