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Mesures hectométriques par interférométrie à longueur d’onde synthétique

Mesures hectométriques par interférométrie à longueur d’onde synthétique. Journées Télémétrie Laser 20 & 21 octobre 2011 Observatoire de la Côte d’azur, Nice. 2011. Sheherazade Azouigui, Thomas Badr, Patrick Juncar, Marc Himbert, Jean-Pierre Wallerand

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Mesures hectométriques par interférométrie à longueur d’onde synthétique

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  1. Mesureshectométriques par interférométrie à longueurd’ondesynthétique Journées Télémétrie Laser 20 & 21 octobre 2011 Observatoire de la Côte d’azur, Nice.2011 Sheherazade Azouigui, Thomas Badr, Patrick Juncar, Marc Himbert,Jean-Pierre Wallerand LCM LNE-CNAM (Laboratoire Commun de Métrologie LNE-CNAM)

  2. OUTLINE • Cadre de ce travail • Principe de l’interférométrie à longueur d’onde synthétique et montage • Comparaison en extérieur au FGI (Nummela, Finland) (v1 version) • Validation en intérieur au VSL (Delft, Netherlands) (v2 version) • Comparaison en extérieur au BEV (Innsbruck, Austria) (v2 version) • Conclusions et suite

  3. FRAMEWORK OF THE WORK EURAMET EMRP-JRP « Long distance » Aim: improve state of the art in distance measurement in air L / L  10-7 10-6/K RH 4% Synthetic wavelength Beat frequency Pulse pulse interferometry Spectroscopy Effective air index measurement Optical phase shift measurement Dispersion Distance measurement

  4. Two-wavelength interferometry 1 M1 M2 D S 2

  5. THE SETUP OPTICAL SETUP Signaux à f1 & f2 : 2 interféromètres hétérodynes Après élévation au carré: signal à f1-f2 Interféromètre superhétérodyne LASER HEAD MEASUREMENT HEAD (20 GHz)

  6. SYSTEME D’ACQUISITION f3=119.99 MHz

  7. LE TELEMETRE

  8. OUTDOOR COMPARISON AT NUMMELA BASELINE Nummela Standard Baseline – September 2010 6 benchmark bolts in underground concrete pillars at 0, 24, 72, 216, 432 and 864 m (± 0.08 mm)

  9. RESOLUTION OF THE SYSTEM ~ 5 µm @T=1 s D ~ 50 m SW ~ 7.5 mm ~ 2 µm @T=10 s ~ 0.7 µm @T=60 s Fringe interpolation ~ 2p/1000 @ T=1 s ~ 2p/5000 @ T=60 s

  10. INDOOR COMPARISON VSL – April 2011 • Displacement bench of 50 m but only 25 m available • Using a classical optical system (fringe counting) as the reference system Spindler & Hoyer, He-Ne laser-based interferometer Agreement ~5-10 mm

  11. OUTDOOR COMPARISON AT BEV BASELINE BEV BASELINE – MAY 2011 • Difficult location close to the motorway • Very busy traffic • Very sunny days  Measurements only possible during 3 evenings

  12. OUTDOOR COMPARISON AT BEV BASELINE BEV BASELINE – MAY 2011 • Pillar 3 – Pillar 1 : D=120.03612 ±0.21mm (FGI – Sept. 2008) • Reproducibility without touching the tribrack and level: ~20µm • Reproducibility with only moving the holder on the tribrack : ~25 µm • Reproducibility with moving the tribrack, centring and levelling adjustment: ~180 µm • No possibility to state the accuracy at better than 210 µm

  13. CONCLUSION • Distancemeter with micrometer resolution • Accuracybetterthan 10 µm (couldbeimproved by consideringelectroniccrosstalk) • Outdoorwith quiet environment, demonstration of measurements over 864 m • Reproducibility of 20 µm demonstrated over 120 m • Difficult to use with « very » perturbatedatmosphere • Stilllimited by temperaturemeasurement for long distances (targetuncertainty not reach) • Possibility to include dispersion temperaturemeasurementswith YAG lasers (PTB alreadydemonstrated over 100 m) “Transportable distance measurement system based on superheterodyneinterferometry using two phase-locked frequency-doubled Nd:YAG lasers”, S. Azouigui,T. Badr, J.-P. Wallerand, M. Himbert, J. Salgado and P. Juncar REVIEW OF SCIENTIFIC INSTRUMENTS 81, 053112 (2010) “Transportable Distance Measurement System for Long-Range Applications”, Shéhérazade Azouigui, Thomas Badr, Jean-Pierre Wallerand, Marc Himbert, José-Antonio Salgado, Jean-Paul Senelaer, Frédéric Kwasnik, and Patrick Juncar IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 60, NO. 7, JULY 2011

  14. EN COURS • Mise en place d’un système de mesure de déphasage du battement entre les deux lasers verts: 10 GHz Tête laser 10 GHz 10 GHz RF meas LO 10 GHz+50 kHz 50 kHz PC DAQ ref 50 kHz Idem pour PDref Premier résultat résolution 0.02° sur ~500 ms.(~1µm pour 10 GHz)

  15. A FAIRE RAPIDEMENT Compensation partielle de l’indice de l’air: Mesure de température par mesure de distance L à 2 longueurs d’onde (532 nm et 1064 nm) Ln1 = L01Ln2 = L02 Pour de l’air sec, on montre que: L = L01 − A(L02 − L01) (A fonction uniquement de l01 et l02) Pour de l’air humide, on a une relation plus complexe qui suppose une mesure de l’humidité (et du taux de CO2) • Déjà démontré jusqu’à 100 m par longueur d’onde synthétique (PTB, Allemagne) “Refractive index determination in length measurement by two-colour interferometry”, Karl Meiners-Hagen and Ahmed Abou-Zeid, Meas. Sci. Technol. 19 (2008) 084004 (5pp)

  16. Merci de votre attention This research was in part funded by the European Community’s Seventh Framework Programme ERA-NET Plus, under grant agreement 217257. The research was performed within the EURAMET joint research project ‘Absolute Long-distance Measurement in Air’.

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