Long-baseline optical fiber interferometer instruments and science

Abstract

b MIRA project, National Astronomical Observatory of Japan Developments of fiber linked optical interferometer are reported. This interferometer is a part of MIRA-I.2 interferometer (Mitaka InfraRed and optical Array). MIRA-I.2 is an optical interferometer with a 30 meters long baseline. It consists of two 30cm siderostats, tip-tilt mirrors, vacuum pipes delay lines and detectors. We plan to use two 60 meters long polarization-maintaining fibers for arms of the interferometer, instead of vacuum pipes. The developments include dispersion and polarization compensation of fiber and fiber injection module. In laboratory experiments, dispersion compensation succeeded. The fringe visibility was 0.93 for wide-band, where the central wavelength of light was 700nm, and bandwidth was 200nm, while 0.95 with a He-Ne laser. We used BK7 glass wedge for dispersion compensation. About fiber injection module, basic optical design has completed. The results of our fiber interferometer could contribute to OHANA (Optical Hawaiian Array for Nanoradian Astronomy) project. We present new science targets, white dwarves and T Tauri stars, and an 800m delayline concept in CFHT for the project.

Towards reliable uncertainties in IR interferometry: the bootstrap for correlated statistical and systematic errors

“…"Statistical" errors-deviations of expected mean zero-on interferometric observables are produced by fastvarying intrinsic, atmospheric, and instrumental effects. In addition to the detector and photon noises, a few sources of errors that have been observed at the Very Large Telescope Interferometer (VLTI) are the differential atmospheric piston (Colavita 1999;Esposito et al 2000), imperfect fibre injection (Kotani et al 2003), mechanical vibrations (Le Bouquin et al 2011, Sect. 5.6), background fluctuations (Absil et al 2004), detector efficiency variations due to cooling cycle (Absil et al 2004), and 50 Hz electronic noise from the power grid (Absil et al 2004).…”

MIRA-I.2: recent progress

“…We expect to start a part of the scientific observing runs in the fall of 2004 for stars selected suitably for our interferometer, single stars, binaries, and variables. Large array proposals as `OHANA 10,11,12,13,14 and the next stage of MIRA 10,15 are also in sight for us. The latter consists of D>1m, B>500m, and N>3 telescopes, and we hope to make further considerations how to realize it.…”

“Modal Noise” in Single-Mode Fibers: A Cautionary Note for High Precision Radial Velocity Instruments

“…The consequences of this variable birefringence have been studied for interferometric applications (e.g. Anderson et al (2014)), as birefringent effects in standard SMFs can degrade fringe contrast (Kotani et al 2003), but they have yet to be thoroughly studied in the context of precision Doppler spectroscopy.…”