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MONALISA at CLIC

Armin Reichold. David Urner. Paul Coe. Matthew Warden. MONALISA at CLIC. Mon itoring , Ali gnment & S tabilisation with high A ccuracy. MONALISA. Is an interferometric metrology system for continuous monitoring of position critical accelerator components

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MONALISA at CLIC

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  1. Armin Reichold David Urner Paul Coe Matthew Warden MONALISAat CLIC Monitoring, Alignment &Stabilisationwith highAccuracy

  2. MONALISA • Is an interferometric metrology system for continuous monitoring of position critical accelerator components • Consists of a fixed network of evacuated interferometric distance meters D. Urner

  3. Concepts D. Urner

  4. Compact Straightness Monitor • 6D position transferred from left to right • breaking of symmetries is important • Preliminary simulation results of CSM Resolution: • sy:10nm • distance meter resolution: 1nm = Resolution in z-direction • Positional change of optics components with respect to each other: 1nm. That’s the challenge! 10cm D. Urner

  5. Absolute distance Displacement Measurement lines • We measure distances along measurement lines using two techniques: • Absolute distance interferometry <mm resolutions • Displacement interferometry nm resolutions • Each line is the same, and is capable of performing both types of measurement. D. Urner

  6. Intensity Interferometer operation D. Urner

  7. ΔD = (c/2πν) ΔΦ D = (c/ 2π) (ΔΦ/Δnu) D = R (ΔΦ/Δθ) Fixed Frequency Interferometry Frequency Scanning Interferometry Interferometer operation Phase = 2π (Optical Path Distance) / Wavelength Φ = 2π D / λ = 2π D (ν / c) frequeny scanning R = (c/ 2π) (Δθ/Δnu) D. Urner

  8. Distance meter • Measurement Frequencies: • FFI: up to 10kHz • FSI: up to 1Hz • Long term stability determines low frequency behaviour • Minutes possible • Lot of work needed to extend to hours or days. • Advantage of interferometric measurement system is fairly low cost per line. • Use of telecom frequency allows use of cheap commercial hardware • Cheap amplification of light • Current estimate: as low as £800 per distance metre D. Urner

  9. Current Status D. Urner

  10. Fixed Frequency Interferometry Measurement over 400mm distance D. Urner

  11. Add box to reduce air turbulence s=750nm s=70nm Measurement over 400mm distance Frequency Scanning Interferometry D. Urner

  12. Fixed Frequency Interferometry • Must reach low level of uncertainty for: • Laser frequency • Refractive index D. Urner

  13. Vacuum System Tapered hole Vacuum vessel wall 8 way fibre ribbon D. Urner

  14. Frequency Stabilisation • Lock laser to spectral feature of rubidium • Use a frequency doubling crystal to reach this frequency D. Urner

  15. ATF2 Final focus region Final Focus Quadrupole Shintake Monitor Operation at KEK D. Urner

  16. Summary • Current status • 5nm FFI resolution (at 400mm distance) • 70nm FSI resolution (at 400mm distance) • Future • Reduce uncertainties with vacuum and laser stabilisation for FFI and dual laser scanning for FSI • Test a full system in an accelerator environment at KEK • Monitor beam-line element at CTF3 • Improve resolution to sub-nanometer scale D. Urner

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