NIF final optics system: frequency conversion and beam conditioning

Abstract

Installation and commissioning of the first of forty-eight Final Optics Assemblies on the National Ignition Facility was completed this past year. This activity culminated in the delivery of first light to a target. The final optics design is described and selected results from first-article commissioning and performance tests are presented.

MRF applications: on the road to making large-aperture ultraviolet laser resistant continuous phase plates for high-power lasers

“…We were able to provide experimental data demonstrating that high-performance optics can be made and imprinted using MRF using small optics fabricated at LLNL and large-aperture optics made using optimized manufacturing processes. In particular, we have shown that a CPP manufactured using advanced finishing protocols and performed beyond expectation during damage testing by sustaining only two damage sites, one at 12 J/cm 2 and one at 14 J/cm 2 . This result provides a basis for using MRF imprinting as a method of making CPPs that can be placed in either the infrared (1053 nm) and the ultraviolet (351 nm) portions of high-powered laser systems operating at or around 3-nsec pulse width.…”

“…Our development of CPP imprinting technology has, for the most part, focused upon applications where the CPPs are used in the infrared (1053 nm) portion of high-power laser systems and designed for far-field characteristics in the ultraviolet (351 nm) 2,11 . The CPP designs are, however, achromatic and can be used at any wavelength with nearly constant results.…”

“…Different experimental conditions at the target plane in an ICF laser system require that several different plate designs be manufactured. These conditions include indirect and direct drive implosion cone beams and backlighter/backscatter diagnostic beam drivers [1][2][3] . As such, CPPs are considered user prescribed optics and are tailored for each particular experiment.…”

“…Our group has been successful in the past two years at developing advanced Magnetorheological Finishing (MRF) technology to accurately apply complex topographical patterns onto optical surfaces that can be used to manipulate and control laser beam-shapes, energy distributions, and wavefront profiles. The most interesting and direct application of this advanced technology is its use in the manufacture of large-aperture (430 X 430 mm) custom continuous phase plates (CPPs) to improve on-target irradiation uniformity which, in turn, reduces hydrodynamic instabilities that develop during ICF implosions [1][2][3] .…”

Developing magnetorheological finishing (MRF) technology for the manufacture of large-aperture optics in megajoule class laser systems

“…A major portion of this work centers upon developing and engaging state-of-the-art technology to set the stage for creating nuclear fusion in a laboratory setting. Continuous phase plates (CPPs) form the vital and enabling portion of the optics chain used in these kilojoule-and megajoule-class laser systems because they make it possible to manipulate and control laser beam-shapes, energy distributions, and wavefront profiles 1,2,3,4,5,6,7 . This prescribed beam characteristic control is made possible via manipulation of the incoming wavefront by the CPPs.…”