La corrélation d'images numériques pour le suivi de l'endommagement des optiques du Laser MégaJoule

High energy laser facilities designed for fusion experiments, such as Laser MegaJoule or National Ignition Facility, are limited by laser-induced damage on their final optics. Accurate and early detection of damage growth is required for successful operations of such facilities. Since the image resolution is about the size of damage sites to monitor, diameter measurement is not sufficient to meet the objectives of damage growth quantification. Recently, it was shown that correlation residual could be used to monitor laser-induced damage. The performance of both indicator (residual and diameter) are compared at high and low images resolutions using a highly instrumented laser damage setup. The results prove that correlation residuals are more efficient to detect sub-pixel laser damage growth than diameter measurements at a given resolution. The correlation residual is therefore a powerful indicator for monitoring laser-induced damage at sub-pixel scale.