Vol. 8 (2005) > lrr-2005-4
doi: 10.12942/lrr-2005-4
Living Rev. Relativity 8 (2005), 4
Time-Delay Interferometry
1 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, U.S.A. and LIGO Laboratory, California Institute of Technology, Pasadena, CA 91125, U.S.A.
2 IUCAA, Post Bag 4, Ganeshkhind, Pune 411 007, India
2 IUCAA, Post Bag 4, Ganeshkhind, Pune 411 007, India
Article Abstract
Equal-arm interferometric detectors of gravitational radiation allow phase measurements many orders of magnitude below the intrinsic phase stability of the laser injecting light into their arms. This is because the noise in the laser light is common to both arms, experiencing exactly the same delay, and thus cancels when it is differenced at the photo detector. In this situation, much lower level secondary noises then set the overall performance. If, however, the two arms have different lengths (as will necessarily be the case with space-borne interferometers), the laser noise experiences different delays in the two arms and will hence not directly cancel at the detector. In order to solve this problem, a technique involving heterodyne interferometry with unequal arm lengths and independent phase-difference readouts has been proposed. It relies on properly time-shifting and linearly combining independent Doppler measurements, and for this reason it has been called Time-Delay Interferometry (TDI). This article provides an overview of the theory and mathematical foundations of TDI as it will be implemented by the forthcoming space-based interferometers such as the Laser Interferometer Space Antenna (LISA) mission. We have purposely left out from this first version of our "Living Review" article on TDI all the results of more practical and experimental nature, as well as all the aspects of TDI that the data analysts will need to account for when analyzing the LISA TDI data combinations. Our forthcoming "second edition" of this review paper will include these topics.
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Article Citation
Since a Living Reviews in Relativity article may evolve over time, please cite the access <date>, which uniquely identifies the version of the article you are referring to:
Massimo Tinto and Sanjeev V. Dhurandhar,
"Time-Delay Interferometry",
Living Rev. Relativity 8, (2005), 4. URL (cited on <date>):
http://www.livingreviews.org/lrr-2005-4
Article History
| ORIGINAL | http://www.livingreviews.org/lrr-2005-4 |
|---|---|
| Title | Time-Delay Interferometry |
| Author | Massimo Tinto / Sanjeev V. Dhurandhar |
| Date | accepted 16 May 2005, published 15 July 2005 |
| UPDATE | http://www.livingreviews.org/lrr-2014-6 |
| Title | Time-Delay Interferometry |
| Author | Massimo Tinto / Sanjeev V. Dhurandhar |
| Date | accepted 28 July 2014, published 5 August 2014 |
| Changes | Major revision, updated and expanded. The number of references increased from 35 to 65. This revised version includes new and major theoretical and experimental results that have appeared in the literature since the original review got released. The new Section 5.3 covers recent work performed by S.V.D. and collaborators on the mathematical foundations of second-generation TDI. Section 5.4 instead addresses the derivation of the TDI space corresponding to a laser interferometer architecture with only two arms. This covers both the LISA mission in the eventuality of failure of one of its arms, or other mission concepts in which by design only two arms are envisioned. Finally, in Section 7 some practical and experimental aspects related to the performance specifications of the different subsystems used for implementing TDI have been included. |
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