Sub-pixel detection of laser-induced damage and its growth on fused silica optics using registration residuals.

Fused silica optics are key components to manipulate high energy Inertial Confinement Fusion (ICF) laser beams but their optical properties can be degraded by laser-induced damage. The detection of laser damage sites is of major importance. The challenge is to monitor damage initiation and growth at sub-pixel scale with highly sensitive measurements.

Parametric study of laser-induced damage growth in fused silica optics with large beams at 351 nm. Part 2: fractal analysis.

The impact of laser fluence and pulse duration on both the rate and probability of growth of laser-induced damage sites has been reported and analyzed statistically in a companion paper. In this paper, we report and analyze the volume morphology of damage sites during the growth process in fused silica optical components, at 351 nm, under various laser fluence and pulse durations. Fractal analysis has been used to quantify the bulk damage morphology.

Parametric study of laser-induced damage growth in fused silica optics with large beams at 351 nm. Part 1: stochastic approach.

Both the rate and probability of the growth of laser-induced damage sites in fused silica depend on several parameters. In this two-part paper, we investigate the impact of the laser parameters on damage growth. In Part I, we present statistical measurements of damage growth at different energy densities, pulse durations, and initial damage sizes.

Interference filters and their impact on FM-to-AM conversion: a method for investigation and characterization.

High-power nanosecond laser pulses are usually spectrally broadened via temporal phase modulations to tackle the issue of stimulated Brillouin scattering and to achieve optical smoothing of the focal spot. While propagating along the beamline, such pulses can undergo frequency modulation to amplitude modulation (FM-to-AM) conversion. This phenomenon induces modulations of the optical power that can have a strong impact on laser performance.

A powerful tool for comparing different test procedures to measure the probability and density of laser induced damage on optical materials.

The determination of the laser damage resistance of optics in the nanosecond regime is based on statistical tests and approaches because the response of the components is mainly related to the presence of defects randomly distributed in the optics and is therefore probabilistic in nature. For practical reasons, the tests are mostly carried out with beams of small dimensions (several tens of micrometer), that make it possible to determine a damage probability from which a laser damage threshold is extracted. This threshold is, however, highly correlated with the size of the test beam and the sampling of the test procedure.