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Time-Delay Interferometry.

Living reviews in relativity·2017
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Time-Delay Interferometry.

Massimo Tinto1, Sanjeev V Dhurandhar2

  • 1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 USA ; LIGO Laboratory, California Institute of Technology, Pasadena, CA 91125 USA.

Living Reviews in Relativity
|February 7, 2017
PubMed
Summary

Time-Delay Interferometry (TDI) addresses laser noise cancellation challenges in unequal-arm space-based gravitational wave detectors. This technique ensures accurate phase measurements by time-shifting and combining Doppler data, crucial for missions like LISA.

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Area of Science:

  • Astrophysics
  • Gravitational Wave Detection
  • Optical Interferometry

Background:

  • Equal-arm interferometers achieve high precision by canceling laser noise common to both arms.
  • Unequal arm lengths in space-based interferometers cause differential laser delays, preventing direct noise cancellation.
  • Secondary noise sources limit performance when primary laser noise is effectively suppressed.

Purpose of the Study:

  • To provide a theoretical and mathematical overview of Time-Delay Interferometry (TDI).
  • To explain how TDI enables precise gravitational wave measurements with unequal arm lengths in space missions.
  • To lay the groundwork for understanding TDI implementation in future observatories like LISA.

Main Methods:

  • Heterodyne interferometry with unequal arm lengths and independent phase-difference readouts.
  • Time-shifting and linear combination of independent Doppler measurements.
  • Theoretical analysis of noise cancellation mechanisms in TDI.

Main Results:

  • TDI effectively cancels laser noise in unequal-arm interferometers by processing Doppler measurements.
  • The technique allows for phase measurements orders of magnitude below intrinsic laser stability.
  • Mathematical foundations for TDI implementation in space-based gravitational wave detectors are established.

Conclusions:

  • TDI is a critical technique for the success of space-based gravitational wave observatories.
  • The theoretical framework presented is essential for understanding and implementing TDI.
  • Future work will include practical and experimental aspects of TDI for data analysis.