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Coming clean: understanding and mitigating optical contamination and laser induced damage in advanced LIGO

Gushwa, Kaitlin E. and Torrie, Calum I. (2014) Coming clean: understanding and mitigating optical contamination and laser induced damage in advanced LIGO. In: Laser-Induced Damage in Optical Materials: 2014. Proceedings of SPIE. No.9237. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 923702. ISBN 978-1-62841-300-7.

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The cleanliness of optical surfaces is of great concern as the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) project transitions from installation to operation at full power. More particulates than expected were observed on and near the core optics as a result of assembly and installation work, prompting a re-evaluation of longheld contamination control practices. Even low particulate levels can potentially damage the fused silica optics and reduce overall interferometer sensitivity. These risks are mitigated from a combination of the following approaches: quantifying the extent of the contamination, identifying its sources, improving practices to reduce the generation of particulates, introducing a non-contact in-situ cleaning technique for suspended optics in air, qualifying cleanliness levels against induced damage, and developing methods for remotely measuring and cleaning suspended optics under vacuum. While significant progress has been made in understanding and mitigating contamination, and thus, protecting the optics from losses and damage, there is still more work to be done to reach ultimate performance requirements.

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Additional Information:© 2014 SPIE. The authors gratefully acknowledge the support of the United States National Science Foundation (award No. PHY-0757058). LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation, and operates under cooperative agreement PHY-0107417. Caltech also acknowledges financial support from the Science and Technology Facilities Council of the United Kingdom. This paper filed internally under LIGO document number LIGO- P1400205. LIGO Internal Reports may be accessed at The authors wish to acknowledge the many colleagues in LIGO and the LIGO Scientific Collaboration who have supported this work. In particular, the authors would like to thank Jeff Bartlett, Garilynn Billingsley, Dennis Coyne, Eric Gustafson, Matthew Heintze, Norna Robertson, Betsy Weaver and Liyuan Zhang within LIGO. In addition, the authors would like to thank all of the excellent contacts they now have within the National Ignition Facility.
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Science and Technology Facilities Council (STFC)UNSPECIFIED
Subject Keywords:LIGO; gravitational waves; ultra-high vacuum system; coated fused silica optics; damage, absorption and scatter; contamination control; particulate cleanliness level; obscuration ratio
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LIGO Document NumberLIGO-P1400205
Series Name:Proceedings of SPIE
Issue or Number:9237
Record Number:CaltechAUTHORS:20150311-104401320
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Official Citation:Kaitlin E. Gushwa and Calum I. Torrie "Coming clean: understanding and mitigating optical contamination and laser induced damage in advanced LIGO", Proc. SPIE 9237, Laser-Induced Damage in Optical Materials: 2014, 923702 (October 31, 2014); doi:10.1117/12.2066909;
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:55699
Deposited By: Jason Perez
Deposited On:11 Mar 2015 23:17
Last Modified:10 Nov 2021 20:49

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