Simple method for temporal study of subpicosecond distributed feedback dye lasers.

The spectral and temporal behaviour of subpicosecond DFDLs are studied. A simple and sensitive spectral diagnostic method is proposed to exhibit the presence and determine the temporal separation and relative amplitude of any following pulse. The measurements were performed in a hybrid excimer-dye laser system generating less than 100 fs pulses at 248 nm

Amplified spontaneous emission in short-pulse excimer amplifiers.

We have found a simple analytical expression which describes the relation between amplified spontaneous emission (ASE) and small-signal gain in short-pulse amplifiers. It is also shown that the contrast of the short pulse to the ASE is weakly dependent on the saturation of the ASE, and influenced mainly by the saturation of the short pulse. The theoretical considerations were verified by measurements

Intensity-dependent loss properties of window materials at 248 nm.

Transmission of fused silica, CaF2, LiF, and MgF2 is measured using 450-fsec, 248-nm pulses in the range 10–120 GW/cm2. Different loss mechanisms such as scattering of transmitted radiation, color-center formation, and multiphoton absorption were studied separately. For fused silica a two-photon absorption mechanism is found, while for CaF2, LiF, and MgF2 three-photon absorption and absorption due to color-center formation are found as dominant absorption mechanisms

Feasibility of a laboratory X-ray laser pumped by ultrashort UV laser pulses.

In order to allow widespread application of soft X-ray lasers there is a strong effort worldwide to use as small as possible pump lasers for plasma production. Short pulse lasers (τ ≈ 1 ps), particularly in the UV, have attracted much interest, since extremely high intensities (up to 1018 W/cm2) can be achieved with a relatively high repetition rate. In this article we discuss their merit for soft X-ray laser pumping and possible solutions to the specific problems, for instance pulse front distortion, nonlinear absorption in window materials, plasma formation by short laser pulses and the relatively low total pump energy

The challenge of ensuring affordability, sustainability, consistency, and adaptability in the common metrics agenda

Summary Mental health research grapples with research waste and stunted field progression caused by inconsistent outcome measurement across studies and clinical settings, which means there is no common language for considering findings. Although recognising that no gold standard measures exist and that all existing measures are flawed in one way or another, anxiety and depression research is spearheading a common metrics movement to harmonise measurement, with several initiatives over the past 5 years recommending the consistent use of specific scales to allow read-across of measurements between studies. For this approach to flourish, however, common metrics must be acceptable and adaptable to a range of contexts and populations, and global access should be as easy and affordable as possible, including in low-income countries. Within a measurement landscape dominated by fixed proprietary measures and with competing views of what should be measured, achieving this goal poses a range of challenges. In this Personal View, we consider tensions between affordability, sustainability, consistency, and adaptability that, if not addressed, risk undermining the common metrics agenda. We outline a three-pronged way forward that involves funders taking more direct responsibility for measure development and dissemination; a move towards managing measure dissemination and adaptation via open-access measure hubs; and transitioning from fixed questionnaires to item banks. We argue that now is the time to start thinking of mental health metrics as 21st century tools to be co-owned and co-created by the mental health community, with support from dedicated infrastructure, coordinating bodies, and funders

Generation of input signals for ArF amplifiers.

Four different schemes for the generation of femtosecond input pulses for ArF amplifiers are described. Pulse energies of 100 nJ were obtained with phase-matched frequency mixing of a Raman-shifted frequency-doubled pulse derived from a 537-nm femtosecond dye-laser pulse. Excellent spatial, spectral, and amplitude stability was obtained when a broadband, nanosecond dye laser at 690 nm was used as a Raman seed pulse. Preliminary amplification experiments resulted in 0.5-mJ ArF output pulses of 340 fsec