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Proceedings Paper

Production of distributed phase plates using an energetic ion process
Author(s): Douglas J. Smith; Joy A. Warner; Nelson E. LeBarron; Salvatore LaDelia
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Paper Abstract

Laser-driven implosion experiments require optical phase conversion to create a uniformly irradiated target. Distributed phase plates provide a quasi-random phase front that aids in beam smoothing on the target; however, the DPP must survive the high fluences of the tripled OMEGA beam at 351 nm. The continuous DPP produces higher efficiency and less risk of damage to opposing optics than the previous binary design. DPPs are created by exposing a gray scale pattern in photoresist and then etching the pattern in to silica. Several problems were solved during the development stage of ion etching DPPs. The etch uniformity was limited to less than 6 percent across a 28-cm clear aperture by modeling the 16-cm ion source and erosion characteristics of the photoresist and silica. Surface texturing was linked to overheating of the photoresist by the ion source and was solved by radiant cooling. Near-field defects capable of focusing damage in levels of fluence on downstream optics were created in the photoresist exposure process and were removed after etching. The damage thresholds of the silica surface generally increase after etching is fare is taken to avoid re-sputtering of tooling onto the optics surface. Sixty ion-etched DPPs were installed in December 1997 and, currently, damage has not been observed on the optics.

Paper Details

Date Published: 7 April 1999
PDF: 16 pages
Proc. SPIE 3578, Laser-Induced Damage in Optical Materials: 1998, (7 April 1999); doi: 10.1117/12.344448
Show Author Affiliations
Douglas J. Smith, Univ. of Rochester (United States)
Joy A. Warner, Univ. of Rochester (United States)
Nelson E. LeBarron, Univ. of Rochester (United States)
Salvatore LaDelia, Univ. of Rochester (United States)


Published in SPIE Proceedings Vol. 3578:
Laser-Induced Damage in Optical Materials: 1998
Gregory J. Exarhos; Arthur H. Guenther; Mark R. Kozlowski; Keith L. Lewis; M. J. Soileau, Editor(s)

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