Abstract

We report on the recent progress in contrast campaign for Astra-Gemini laser. An experimental study shows that the main contributions to the so-called “coherent” contrast feature come from the diffraction gratings in the stretcher. Replacing the gratings by higher-quality optics resulted in contrast enhancement by an order of magnitude. Further enhancement of coherent contrast by 4 orders of magnitude was also demonstrated using double plasma mirrors (DPM). The replica prepulses were also greatly suppressed in new amplifiers by employing the wedged crystal and optics to provide very clean laser pulses.

© 2012 Optical Society of America