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LASER FRAME: Straightness monitor (Tentative results of resolution test)

LASER FRAME: Straightness monitor (Tentative results of resolution test). Third Mini-Workshop on Nano Project at ATF May 30-31,2005 KEK Nano BPM Group Y.Higashi, Y.Honda, T.Tauchi, H.Hayano, J.Urakawa, T.Kume, K.Kubo, H.Yamaoka. Outline. Why we need Laser Frame as Straightness monitor

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LASER FRAME: Straightness monitor (Tentative results of resolution test)

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  1. LASER FRAME: Straightness monitor(Tentative results of resolution test) Third Mini-Workshop on Nano Project at ATF May 30-31,2005 KEK Nano BPM Group Y.Higashi, Y.Honda, T.Tauchi, H.Hayano, J.Urakawa, T.Kume, K.Kubo, H.Yamaoka

  2. Outline • Why we need Laser Frame as Straightness monitor • Complete design of the Laser Frame Configuration • Laser BPM Assembly • Tentative results of resolution test • Long distance(50-100m) straightness monitor base on the laser frame techniques • Schedule for the summer installation

  3. Why we need Laser Frame Initial alignment (10 mm) of the cavity BPM OD of cavities will be used as reference Fine alignment using BPMs signals Needs Nano-Movers Needs stable position of base of movers, magnets etc. with nm order Needs reference lines Laser Frame as Straightness monitor

  4. Concept of Laser Frame We use; @ Laser-BPM @ Interferometer @ Vacuum environment

  5. Laser BPM Reference Bar D2 D1 Ref.2 Ref.1 P1 P1=D11-D12 P2=D21-D22 dP1=2Lsin q +dy dP2=Lsin q +dy sin q= (dP1-dp2)/L dy= dP1+Lsin q D12 D11 q 2L dy L D21 D22

  6. GroundMotionMeasurement To reference Bar Laser BPM Mirror for Interferometer Two Laser Beam O rings Vacuum Chamber Plate O rings GroundSurface

  7. Measurement of intensity change of light due to nm position shift of laser lightTested by Y.Honda

  8. Over view of KEK Nano BPM

  9. Vertical Interferometer Reference Bar Extended Reference Bar Plane Mirror Leg Vacuum pipe, chamber B.S, Mirror, Detector Laser Beam from Fiber Laser BPM Two Beam Optics

  10. Cross sectional drawing of a Laser BPM(including vacuum chamber) To detector Laser ray Vacuum chamber Ground

  11. Resolution test setup conditions =>Laser: YAG Laser (CW,500mW, 532nm, Single mode, W0=0.9mm, Divergence 1mrad. Spot size 2900mm, Rayleigh length = πw0^2 /λ= 4.8 m) =>Environment (not vacuum but transport in the pipe ) =>BPM location (2 m distance from the reference beam generator) =>Beam splitter ( PBS 50% transmission) =>Detector (diff. amp gain 100-10000) =>Base (Granite table 1x2m. 0.3m thick no apply vibration isolator) =>BPM movement ( measured by capacitance gauge(resolution: 3nm) =>Tilt measurement ( light lever ratio 1:2)

  12. Measuring items Use a Single Laser BPM =>Vertical resolution =>Tilt resolution

  13. Calibration setup of beam position measurment(1) 4th BPM Laser 2 m Reference beam generator

  14. Setup (2) 3rd BPM 2nd BPM YAG Laser 500mW 1st BPM Beam divider Beam intensity of nth BPM= p* 0.5n (n= BPM number, p=power) Optical fiber

  15. Resolution test of the 4th BPM Laser ray Vacuum chamber

  16. Tentative results of resolution

  17. Summary • Vertical resolution => 10 nm • Tilt resolution => 5x10-6 rad. • Need to Test => Long distance (10-2 0m) • Interferometer test in 1m distance

  18. Laser beam based alignment for JHF proton Linac

  19. Long distance alignment test length about 100m

  20. Laser position change at 50m away due to environmental change

  21. Laser position change at 100m away due to environmental change

  22. Reference Bar

  23. Laser Input

  24. Distance change between Reference Bar and cavity(Due to the environmental change) 7 mm 1 hour

  25. Deviation due to assembling and fabrication errors (2Kgf) -0.4mm -0.6mm +0.4mm dY -0.4mm +0.1mm -0.1mm

  26. Schedule for summer installation

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