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Time-Delay Interferometry (TDI) is the data processing technique that cancels the large laser phase fluctuations affecting the one-way Doppler measurements made by unequal-arm space-based gravitational wave interferometers. By taking finite…

General Relativity and Quantum Cosmology · Physics 2021-08-25 Massimo Tinto , Sanjeev Dhurandhar , Prasanna Joshi

In the detection of gravitational waves in space, the arm lengths between spacecraft are not equal due to their orbital motion. Consequently, the equal arm length Michelson interferometer used in Earth laboratories is not suitable for…

General Relativity and Quantum Cosmology · Physics 2024-06-21 Gang Wang

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…

General Relativity and Quantum Cosmology · Physics 2021-03-25 Massimo Tinto , Sanjeev V. Dhurandhar

The VLTI instrument GRAVITY will provide very powerful astrometry by combining the light from four telescopes for two objects simultaneously. It will measure the angular separation between the two astronomical objects to a precision of 10…

Space-borne interferometric gravitational-wave detectors, sensitive in the low-frequency (mHz) band, will fly in the next decade. In these detectors, the spacecraft-to-spacecraft light-travel times will necessarily be unequal and…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Massimo Tinto , Michele Vallisneri , J. W. Armstrong

We demonstrate the ability to measure precise stellar barycentric radial velocities with the dispersed fixed-delay interferometer technique using the Exoplanet Tracker (ET), an instrument primarily designed for precision differential…

Obtaining lensing time delay measurements requires long-term monitoring campaigns with a high enough resolution (< 1 arcsec) to separate the multiple images. In the radio, a limited number of high-resolution interferometer arrays make these…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-21 G. Gurkan , N. Jackson , L. V. E. Koopmans , C. D. Fassnacht , A. Berciano Alba

Very Long Baseline Interferometry (VLBI) measures two standard observables: group delay and fringe frequency (delay rate). While group delay is widely used to estimate a broad range of geodetic and astrometric parameters, fringe frequency…

Instrumentation and Methods for Astrophysics · Physics 2025-07-08 Oleg Titov

Spaceborne gravitational-wave observatories utilize a postprocessing technique known as time-delay interferometry (TDI) to reduce the otherwise overwhelming laser frequency noise by around 8 orders of magnitude. While, in its traditional…

Instrumentation and Methods for Astrophysics · Physics 2025-06-11 Kohei Yamamoto , Jan Niklas Reinhardt , Olaf Hartwig

In the context of the Laser Interferometer Space Antenna (LISA), the laser subsystems exhibit frequency fluctuations that introduce significant levels of noise into the measurements, surpassing the gravitational wave signal by several…

Instrumentation and Detectors · Physics 2024-01-15 Philipp Euringer , Niklas Houba , Gerald Hechenblaikner , Oliver Mandel , Francis Soualle , Walter Fichter

An accurate measurement of the bunching of photons in the fluorescent emission from an ultracold ensemble of thermal 87Rb atoms in a steady-state magneto-optical trap is presented. Time-delayed-intensity-interferometry (TDII) performed with…

Atomic Physics · Physics 2015-02-24 Muhammed Shafi K. , Deepak Pandey , Buti Suryabrahmam , B. S. Girish , Hema Ramachandran

Orthogonal delay-Doppler (DD) division multiplexing (ODDM) has been recently proposed as a promising multicarrier modulation scheme to tackle Doppler spread in high-mobility environments. Accurate channel estimation is of paramount…

Signal Processing · Electrical Eng. & Systems 2024-07-10 Yaru Shan , Akram Shafie , Jinhong Yuan , Fanggang Wang

The derivation of radial velocities from large numbers of spectra that typically result from survey work, requires automation. However, except for the classical cases of slowly rotating late-type spectra, existing methods of measuring…

Instrumentation and Methods for Astrophysics · Physics 2014-05-20 M. David , R. Blomme , Y. Frémat , Y. Damerdji , C. Delle Luche , E. Gosset , D. Katz , Y. Viala

Change detection (CD) is fundamental to computer vision and remote sensing, supporting applications in environmental monitoring, disaster response, and urban development. Most CD models assume co-registered inputs, yet real-world imagery…

Computer Vision and Pattern Recognition · Computer Science 2025-12-16 Seyedehanita Madani , Rama Chellappa , Vishal M. Patel

The GRAVITY instrument has been commissioned on the VLTI during 2016 and is now available to the astronomical community. It is the first optical interferometer capable of observing sources as faint as magnitude 19 in K-band. This is…

We describe a time lens to expand the dynamic range of photon Doppler velocimetry (PDV) systems. The principle and preliminary design of a time-lens PDV (TL-PDV) are explained and shown to be feasible through simulations. In a PDV system,…

Optics · Physics 2021-04-14 Pinghan Chu , Velat Kilic , Mark A. Foster , Zhehui Wang

Excessive accumulation of group-delay (GD) spread increases computational complexity and affects tracking of receiver-based multi-input multi-output signal processing, posing challenges to long-haul mode-division multiplexing in multimode…

As the first successful technique used to detect exoplanets orbiting distant stars, the Radial Velocity Method aims to detect a periodic Doppler shift in a star's spectrum. We introduce a new, mathematically rigorous, approach to detect…

Earth and Planetary Astrophysics · Physics 2020-05-29 Parker Holzer , Jessi Cisewski-Kehe , Debra Fischer , Lily Zhao

Particle size measurement is crucial in various applications, be it sizing droplets in inkjet printing or respiratory events, tracking particulate ejection in hypersonic impacts, or detecting floating target markers in free surface flows.…

Fluid Dynamics · Physics 2023-10-04 Saini Jatin Rao , Shubham Sharma , Saptarshi Basu , Cameron Tropea

A variable-delay optical interferometer with 128 actively selectable delays and a technique of active phase stabilization are innovatively designed and applied for the first time in the experiment of round-robin differential phase shift…

Signal Processing · Electrical Eng. & Systems 2019-09-04 Yu Xu , Jin Lin , Yu-Huai Li , Hui Dai , Sheng-Kai Liao , Cheng-Zhi Peng