KrF Laser Optical Train and Staging

1. KrF Laser Optical Train and Staging Presented by: Tom Lehecka Penn State Electro-Optics Center tml15@psu.edu Presented at: High Average Power Laser Program Workshop Lawrence Livermore National Lab June 20-21, 2005 High Average Power Laser Program Workshop

2. Outline • Optical Layout • Front end • Amplifiers • Target area • System parameters • Error budgets • Alignment • Energy • Timing High Average Power Laser Program Workshop

3. Optical Block Diagram Front End Target Area Amplifiers High Average Power Laser Program Workshop

4. 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 High Average Power Laser Program Workshop

5. 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 High Average Power Laser Program Workshop

6. 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 High Average Power Laser Program Workshop

7. 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 High Average Power Laser Program Workshop

8. System Parameters (Laser) High Average Power Laser Program Workshop

9. System Parameters (Optics) High Average Power Laser Program Workshop

10. System Parameters (Target) High Average Power Laser Program Workshop

11. Spot Size Error Budget • Individual beam pointing errors result in a spot size increase and high l-mode non-uniformities High Average Power Laser Program Workshop

12. Beam Pointing Error Budget • Beam cluster pointing errors result in an alignment error on target and mid-range l-mode non-uniformities High Average Power Laser Program Workshop

13. Energy Loss Error Budget • Energy loss will decrease system efficiency High Average Power Laser Program Workshop

14. Beam Balance Error Budget • Beam balance errors result in mid-range l-mode non-uniformities High Average Power Laser Program Workshop

15. Preliminary Timing Diagram • t=0 defined as first laser light on target • This timing diagram will serve as the basis for system timing and timing jitter requirements High Average Power Laser Program Workshop

16. 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 High Average Power Laser Program Workshop