Detection and Tracking of the Back-Reflection of KDP Images in the Presence or Absence of a Phase Mask

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The KDP crystals present in the final optics assembly at the National Ignition Facility (NIF) are used for conversion of infrared laser light beam into ultraviolet. The conversion is highest for a certain incident angle, the alignment of which is determined from the position of the back reflection beam, which exhibits a distinct characteristics shape. When a phase plate device is introduced before the final assembly to increase the uniformity of the beam, the back reflection pattern changes drastically. The algorithm which is best for tracking the special shaped beam is no longer suitable to track the phase modified beam. ... continued below

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PDF-file: 16 pages; size: 0.8 Mbytes

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Awwal, A; McClay, W A; Ferguson, S W; Candy, J V; Salmon, J T & Wegner, P J March 4, 2005.

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The KDP crystals present in the final optics assembly at the National Ignition Facility (NIF) are used for conversion of infrared laser light beam into ultraviolet. The conversion is highest for a certain incident angle, the alignment of which is determined from the position of the back reflection beam, which exhibits a distinct characteristics shape. When a phase plate device is introduced before the final assembly to increase the uniformity of the beam, the back reflection pattern changes drastically. The algorithm which is best for tracking the special shaped beam is no longer suitable to track the phase modified beam. The work presented here discusses our detection schemes for both the situations. In particular, we demonstrate how the algorithm senses the modified beam using a newly proposed criterion of ''correlation peak pedestal area'' and execute an alternate algorithm in real time without operator intervention. This new algorithm continuously tracks the beam pattern to guarantee reliable and repeatable sensing. Results from simulation and real world implementation of the algorithm at the NIF facility are presented.

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PDF-file: 16 pages; size: 0.8 Mbytes

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  • Journal Name: Applied Optics; Journal Volume: 45; Journal Issue: 13

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  • Report No.: UCRL-JRNL-210479
  • Grant Number: W-7405-ENG-48
  • Office of Scientific & Technical Information Report Number: 883834
  • Archival Resource Key: ark:/67531/metadc892370

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • March 4, 2005

Added to The UNT Digital Library

  • Sept. 23, 2016, 2:42 p.m.

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  • Dec. 7, 2016, 10:33 a.m.

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Awwal, A; McClay, W A; Ferguson, S W; Candy, J V; Salmon, J T & Wegner, P J. Detection and Tracking of the Back-Reflection of KDP Images in the Presence or Absence of a Phase Mask, article, March 4, 2005; Livermore, California. (digital.library.unt.edu/ark:/67531/metadc892370/: accessed October 21, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.