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LSC meeting, LLO, March, 18, 2004 LIGO-G040071-00-Z

Institute of Applied Physics of the Russian Academy of Sciences, 603950, Nizhny Novgorod, Russia. Modeling of remote in situ monitoring of  weak distortions in ETM  Ilya Kozhevatov, Efim Khazanov, Anatoly Malshakov, Oleg Palashov,

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LSC meeting, LLO, March, 18, 2004 LIGO-G040071-00-Z

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  1. Institute of Applied Physics of the Russian Academy of Sciences,603950, Nizhny Novgorod, Russia Modeling of remote in situ monitoring of  weak distortions in ETM  Ilya Kozhevatov, Efim Khazanov, Anatoly Malshakov, Oleg Palashov, Anatoly Poteomkin, Alexander Sergeev, Andrey Shaykin, Victor Zelenogorsky Optics group LSC meeting, LLO, March, 18, 2004 LIGO-G040071-00-Z

  2. White Light In Situ Measurement Interferometer (WLISMI)

  3. White Light In Situ Measurement Interferometer. Experimental setup 1 - light source; 2 - objective; 3 - sample; 4 - ocular; 5 - measurement interferometer; 6 - unit for synchroni- zation and control; 7 - CCD camera; 8 - PC computer; 9 - modulating mirror; 10 - adjusting mirror; 11, 13 - motors; 12 - wave front shaper

  4. Heating CO2 laser Vacuum chamber Sample 1 2 2 2 1 Heating Nd laser Remote in situ monitoring of weak distortions emerging under auxiliary laser heating. Setup. 1 - WLPMI 2 - NHS and PIT  Optical sample bulk heating by the fundamental or second harmonic of Nd:YAG laser at a power of 10-20 W  Surface heating with the use of a CO2 laser at power of several Watts  Inducing contamination of a small region (characteristic size of 20-100 micron) on the optical element's surface and focusing of low-power laser radiation (<100 mW) on it

  5. T Z R sample laser z R Remote in situ monitoring of weak distortions emerging under auxiliary laser heating. Simulation. photoelastic effect dn/dT effect dL/dT effect

  6. -7 x 10 2.5 2 1.5 1 0.5 0 -0.5 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 Remote in situ monitoring of weak distortions emerging under auxiliary laser heating. Results. dL,10-7m experiment theory • BK7 glass • cylinder length 2 cm • cylinder radius 3.2 cm • CO2 laser power 0.1 W R, m

  7. Remote in situ monitoring of weak distortions emerging under auxiliary laser heating. Results (2). No heating Heated by CO2 laser. rms=0.32nm (l/2000)

  8. How to install WLISMI in LIGO-I interferometer? Important points. 1.Interfering beam propagate mostly on the same path. The paths are different in the vacuum chamber. 2.Interference pattern appears only if three following item coincide optical paths; angles of beams wave front; planes where image of the source is related This tripled coincidence neglects influence of Fresnel reflections on the interference.

  9. How to install WLISMI in LIGO-I interferometer? ETM, ETM telescope and vacuum window.

  10. How to install WLISMI in LIGO-I interferometer? Idea.

  11. How to install WLISMI in LIGO-I interferometer? Experimental modeling of ETM in situ monitoring.

  12. How to install WLISMI in LIGO-I interferometer? Improvement of interferometer pattern.

  13. How to install WLISMI in LIGO-I interferometer? Final design.

  14. How to install WLISMI in LIGO-I interferometer? Phase distortion dynamics movie. CO2 laser power=1mW CO2 laser beam diameter =1mm Heating duration = 4min Total movie duration= 12min Sample aperture = 35mm

  15. Conclusion  LIGO-IAP Lab has been equipped with several instruments developed at IAP for High-Precision Characterization of LIGO Optical Components  White Light In Situ Measurement Interferometer(WLISMI) for control of LIGO Core Optics has been implemented Version of WLISMI for installation on the end station is modeled experimentally and ready to be installed.

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