Improvements for group delay fringe tracking
نویسنده
چکیده
Group delay fringe tracking using spectrally-dispersed fringes is suitable for stabilising the optical path difference in ground-based astronomical optical interferometers in low light situations. We discuss the performance of group delay tracking algorithms when the effects of atmospheric dispersion, high-frequency atmospheric temporal phase variations, non-ideal path modulation, non-ideal spectral sampling, and the detection artifacts introduced by electron-multiplying CCDs (EMCCDs) are taken into account, and we present ways in which the tracking capability can be optimised in the presence of these effects.
منابع مشابه
Fringe Tracking and Group Delay Tracking Methods for MIDI
The tracking of the white light (central) fringe in a broadband optical/IR interferometer, allows the possibility of long coherent integrations of fringe visibility. Fringe tracking involves the determination of absolute OPD o sets (not just narrowband phase) and either real-time correction of the interferometer's delay lines, or determination of the estimated OPD time series to be applied to t...
متن کاملThe PRIMA Fringe Sensor Unit
Context. The Fringe Sensor Unit (FSU) is the central element of the Phase Referenced Imaging and Micro-arcsecond Astrometry (PRIMA) dual-feed facility and provides fringe sensing for all observation modes, comprising off-axis fringe tracking, phase referenced imaging, and high-accuracy narrow-angle astrometry. It is installed at the Very Large Telescope Interferometer (VLTI) and successfully se...
متن کاملRobust determination of optical path difference: fringe tracking at the infrared optical telescope array interferometer.
We describe the fringe-packet tracking system used to equalize the optical path lengths at the Infrared Optical Telescope Array interferometer. The measurement of closure phases requires obtaining fringes on three baselines simultaneously. This is accomplished by use of an algorithm based on double Fourier interferometry for obtaining the wavelength-dependent phase of the fringes and a group-de...
متن کاملControl interface concepts for CHARA 6-telescope fringe tracking with CHAMP+MIRC
Cophasing six telescopes from the CHARA array, the CHARA-Michigan Phasetracker (CHAMP) and Michigan Infrared Combiner (MIRC) are pushing the frontiers of infrared long-baseline interferometric imaging in key scientific areas such as starand planet-formation. Here we review our concepts and recent improvements on the CHAMP and MIRC control interfaces, which establish the communication to the rea...
متن کاملDelay Compensation on Fuzzy Trajectory Tracking Control of Omni-Directional Mobile Robots
This paper presents a delay compensator fuzzy control for trajectory tracking of omni-directional mobile robots. Fuzzy logic control (FLC) of the robots is a suitable strategy for dealing with model uncertainties, nonlinearities and disturbances. On the other hand, in many robotic applications such as mobile robots, delay phenomenon is able to substantially deteriorate the behavior of system's...
متن کامل