The VIRGO large mirrors: a challenge for low loss coatings

Year: 2004

Authors: Beauville F., Buskulic D., Flaminio R., Marion F., Masserot A., Massonnet L., Mours B., Moreau F., Ramonet J., Tournefier E., Verkindt D., Veziant O., Yvert M., Barille R., Dattilo V., Enard D., Frasconi F., Gennai A., La Penna P., Loupias M., Paoletti F., Bracci L., Calamai G., Campagna E., Conforto G., Cuoco E., Fiori I., Guidi G., Losurdo G., Martelli F., Mazzoni M., Perniola B., Stanga R., Vetrano F., Vicere A., Babusci D., Giordano G., Mackowski JM., Morgado N., Pinard L., Remillieux A., Acernese F., Barone F., Calloni E., De Rosa R., Di Fiore L., Eleuteri A., Milano L., Qipiani K., Ricciardi I., Russo G., Solimeno S., Varvella M., Bondu F., Brillet A., Chassande-Mottin E., Cleva F., Cokelaer T., Coulon JP., Dujardin B., Fournier JD., Heitmann H., Man CN., Mornet F., Pacheco J., Pai A., Trinquet H., Vinet JY., Arnaud N., Barsuglia M., Bizouard MA., Brisson V., Cavalier F., Davier M., Hello P., Heusse P., Kreckelberg S., Boccara C., Loriette V., Moreau J., Reita V., Amico P., Bosi L., Gammaitoni L., Punturo M., Travasso F., Vocca H., Barsotti L., Braccini S., Bradaschia C., Cella G., Corda C., Di Virgilio A., Ferrante I., Fidecaro F., Giazotto A., Majorana E., Holloway L., Passaquieti R., Passuello D., Poggiani R., Toncelli A., Tonelli M., Brocco L., Frasca S., Palomba C., Puppo P., Rapagnani P., Ricci F.

Autors Affiliation: 1 Laboratoire d’Annecy-le-Vieux de physique des particules, Chemin de Bellevue-BP110, 74941 Annecy-le-Vieux Cedex, France
2 European Gravitational Observatory (EGO), Via E Amaldi, I-56021 Cascina (PI), Italy
3 INFN, Sez. Firenze/Urbino,Via G Sansone 1, I-50019 Sesto Fiorentino, Italy
4 Università di Firenze, Firenze, Italy
5 Osservatorio Astrofisico di Arcetri Largo E Fermi 5, I-50125 Firenze, Italy
6 Università di Urbino, Via S Chiara, 27 I-61029 Urbino, Italy
7 INFN, Laboratori Nazionali di Frascati, Via E Fermi, 40, I-00044 Frascati (Roma), Italy
8 SMA—IPNL 22, Boulevard Niels Bohr 69622, Villeurbanne, Lyon Cedex France
9 INFN, sez Napoli, Italy
10 Università di Napoli ‘Federico II’, Complesso Universitario di Monte S Angelo, Via Cintia,I-80126 Napoli, Italy
11 Università di Salerno, Via Ponte Don Melillo, I-4084 Fisciano (Salerno), Italy
12 Observatoire de la Cˆote d’Azur, Département Fresnel Interférométrie Laser pour la Gravitation et l’Astrophysique, BP 4229, 06304 Nice Cedex 4, France
13 Laboratoire de l’Accélérateur Linéaire (LAL), IN2P3/CNRS, Université de Paris-Sud, BP 34, 91898 Orsay Cedex, France
14 ESPCI-10, rue Vauquelin, 75005 Paris, France
15 INFN, Sezione di Perugia, Italy
16 Università di Perugia, Via A Pascoli, I-06123 Perugia, Italy
17 INFN, Sezione di Pisa, Italy
18 Università di Pisa, Via Filippo Buonarroti, 2 I-56127 Pisa, Italy
19 INFN, Sezione di Roma, Italy
20 Università ‘La Sapienza’, Ple A Moro 2, I-00185, Roma, Italy

Abstract: Large optical components (diameter 350 mm), having extremely low loss at 1064 nm, are needed for the large-scale Michelson-type interferometer VIRGO. Today, ion beam sputtering is the only deposition technique able to produce optical components having such performances. Consequently, a large ion beam sputtering deposition system was built to coat large optics up to 700 mm, in diameter: two large substrates may also be coated at the same time for interferometer arm symmetry problem. The performances of this coater are described in terms of layer uniformity on a large scale (wavefront) and optical losses (absorption and scattering). The VIRGO interferometer needs six main mirrors. The first set was ready in June 2002 and they have been installed on the VIRGO site (Italy). The optical performances of this first set are discussed. The requirements at 1064 nm are all satisfied. Indeed, the absorption level is close to 1 ppm (part per million), the scattering is lower than 5 ppm and the RMS wavefront of these optics is lower than 8 nm on 150 mm in diameter. Finally, some solutions are proposed to further improve these performances, especially the absorption level and the mechanical quality factor Q of the mirrors and the substrate wavefront before coating.

Journal/Review: CLASSICAL AND QUANTUM GRAVITY

Volume: 21 (5)      Pages from: S935  to: S945

KeyWords: VIRGO interferometer; low loss coatings;
DOI: 10.1088/0264-9381/21/5/083

Citations: 33
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