KrF Laser Optical Train and Staging

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KrF Laser Optical Train and Staging

• Presented by
• Tom Lehecka
• Penn State Electro-Optics Center
• tml15_at_psu.edu
• Presented at
• High Average Power Laser Program Workshop
• Lawrence Livermore National Lab
• June 20-21, 2005

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Outline

• Optical Layout
• Front end
• Amplifiers
• Target area
• System parameters
• Error budgets
• Alignment
• Energy
• Timing

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Optical Block Diagram
Front End
Target Area
Amplifiers
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Front End Block Diagram
Out to amplifiers

• Fifty beam multiplexer images the Fourier
  transform plane of each beam into the downstream
  amplifier
• A polarization rotator in each beam allows
  optimization of polarization for Grazing
  Incidence final mirror
• Target injection timing information provides
  trigger for laser and pulse shaping

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Fifty-beam Multiplexing Diagram

• Imaging telescope in each beam images Fourier
  transform plane to e-beam amp
• Polarization rotator statically compensates for
  beam rotations and provides correct polarization
  to Grazing Incidence final mirrors

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Amplifier Area Block Diagram
In from front end
Feedback Loop
Out to target area

• Real time (15 Hz) control of large amplifier
  mirrors
• Lens/mirror combination on relay optics for
  astigmatism correction
• Local loop control of relay optics

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Target Area Block Diagram
In from Amplifiers

• A transmissive lens that also serves as a window
  is preferred
• No active optical elements in the neutron path
• Grazing Incidence Metal Mirrors remain the
  baseline for final mirror

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System Parameters (Laser)
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System Parameters (Optics)
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System Parameters (Target)
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Spot Size Error Budget

• Individual beam pointing errors result in a spot
  size increase and high l-mode non-uniformities

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Beam Pointing Error Budget

• Beam cluster pointing errors result in an
  alignment error on target and mid-range l-mode
  non-uniformities

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Energy Loss Error Budget

• Energy loss will decrease system efficiency

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Beam Balance Error Budget

• Beam balance errors result in mid-range l-mode
  non-uniformities

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Preliminary Timing Diagram

• t0 defined as first laser light on target
• This timing diagram will serve as the basis for
  system timing and timing jitter requirements

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Summary

• System engineering for the KrF Laser optical
  train is underway
• Requirements, error budgets and system diagrams
  are being established
• Integration with alignment system, injection
  system and target chamber layout is being
  incorporated
• Optical design and physical dimensioning work has
  started but will be limited by information
  available regarding oscillator, amps and pulse
  shaping
• We have just begun looking at optical materials
  and coatings for the laser fluences involved