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Title: Scalable process for mitigation of laser-damaged potassium dihydrogen phosphate crystal optic surfaces with removal of damaged antireflective coating

Here, we investigate an approach for the recycling of laser-damaged large-aperture deuterated potassium dihydrogen phosphate (DKDP) crystals used for optical switching (KDP) and for frequency conversion (DKDP) in megajoule-class high-power laser systems. The approach consists of micromachining the surface laser damage sites (mitigation), combined with multiple soaks and ultrasonication steps in a coating solvent to remove, synergistically, both the highly adherent machining debris and the laser-damage-affected antireflection coating. We then identify features of the laser-damage-affected coating, such as the “solvent-persistent” coating and the “burned-in” coating, that are difficult to remove by conventional approaches without damaging the surface. We also provide a solution to the erosion problem identified in this work when colloidal coatings are processed during ultrasonication. Finally, we provide a proof of principle of the approach by testing the full process that includes laser damage mitigation of DKDP test parts, coat stripping, reapplication of a new antireflective coat, and a laser damage test demonstrating performance up to at least 12 J/cm 2 at UV wavelengths, which is well above current requirements. Our approach ultimately provides a potential path to a scalable recycling loop for the management of optics in large, high-power laser systems that can reduce cost and extendmore » lifetime of highly valuable and difficult to grow large DKDP crystals.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical and Life Sciences and NIF and Photon Sciences
Publication Date:
Report Number(s):
LLNL-JRNL-712417
Journal ID: ISSN 0003-6935; APOPAI
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Applied Optics
Additional Journal Information:
Journal Volume: 56; Journal Issue: 8; Journal ID: ISSN 0003-6935
Publisher:
Optical Society of America (OSA)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 42 ENGINEERING
OSTI Identifier:
1366904
Alternate Identifier(s):
OSTI ID: 1345553

Elhadj, S., Steele, W. A., VanBlarcom, D. S., Hawley, R. A., Schaffers, K. I., and Geraghty, P.. Scalable process for mitigation of laser-damaged potassium dihydrogen phosphate crystal optic surfaces with removal of damaged antireflective coating. United States: N. p., Web. doi:10.1364/AO.56.002217.
Elhadj, S., Steele, W. A., VanBlarcom, D. S., Hawley, R. A., Schaffers, K. I., & Geraghty, P.. Scalable process for mitigation of laser-damaged potassium dihydrogen phosphate crystal optic surfaces with removal of damaged antireflective coating. United States. doi:10.1364/AO.56.002217.
Elhadj, S., Steele, W. A., VanBlarcom, D. S., Hawley, R. A., Schaffers, K. I., and Geraghty, P.. 2017. "Scalable process for mitigation of laser-damaged potassium dihydrogen phosphate crystal optic surfaces with removal of damaged antireflective coating". United States. doi:10.1364/AO.56.002217. https://www.osti.gov/servlets/purl/1366904.
@article{osti_1366904,
title = {Scalable process for mitigation of laser-damaged potassium dihydrogen phosphate crystal optic surfaces with removal of damaged antireflective coating},
author = {Elhadj, S. and Steele, W. A. and VanBlarcom, D. S. and Hawley, R. A. and Schaffers, K. I. and Geraghty, P.},
abstractNote = {Here, we investigate an approach for the recycling of laser-damaged large-aperture deuterated potassium dihydrogen phosphate (DKDP) crystals used for optical switching (KDP) and for frequency conversion (DKDP) in megajoule-class high-power laser systems. The approach consists of micromachining the surface laser damage sites (mitigation), combined with multiple soaks and ultrasonication steps in a coating solvent to remove, synergistically, both the highly adherent machining debris and the laser-damage-affected antireflection coating. We then identify features of the laser-damage-affected coating, such as the “solvent-persistent” coating and the “burned-in” coating, that are difficult to remove by conventional approaches without damaging the surface. We also provide a solution to the erosion problem identified in this work when colloidal coatings are processed during ultrasonication. Finally, we provide a proof of principle of the approach by testing the full process that includes laser damage mitigation of DKDP test parts, coat stripping, reapplication of a new antireflective coat, and a laser damage test demonstrating performance up to at least 12 J/cm2 at UV wavelengths, which is well above current requirements. Our approach ultimately provides a potential path to a scalable recycling loop for the management of optics in large, high-power laser systems that can reduce cost and extend lifetime of highly valuable and difficult to grow large DKDP crystals.},
doi = {10.1364/AO.56.002217},
journal = {Applied Optics},
number = 8,
volume = 56,
place = {United States},
year = {2017},
month = {3}
}