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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Efficiently feeding single-mode fiber photonic spectrographs with an extreme adaptive optics system: on-sky characterization and preliminary spectroscopy

Jovanovic, N., Cvetojevic, N., Schwab, C., Norris, B., Lozi, J., Gross, S., Betters, C., Singh, G., Guyon, O., Martinache, F., Doughty, D., Tuthill, P. 03 August 2016 (has links)
High-order wavefront correction is not only beneficial for high-contrast imaging, but also spectroscopy. The size of a spectrograph can be decoupled from the size of the telescope aperture by moving to the diffraction limit which has strong implications for ELT based instrument design. Here we present the construction and characterization of an extremely efficient single-mode fiber feed behind an extreme adaptive optics system (SCExAO). We show that this feed can indeed be utilized to great success by photonic-based spectrographs. We present metrics to quantify the system performance and some preliminary spectra delivered by the compact spectrograph.
2

Precision single mode fibre integral field spectroscopy with the RHEA spectrograph

Rains, Adam D., Ireland, Michael J., Jovanovic, Nemanja, Feger, Tobias, Bento, Joao, Schwab, Christian, Coutts, David W., Guyon, Olivier, Arriola, Alexander, Gross, Simon 09 August 2016 (has links)
The RHEA Spectrograph is a single-mode echelle spectrograph designed to be a replicable and cost effective method of undertaking precision radial velocity measurements. Two versions of RHEA currently exist, one located at the Australian National University in Canberra, Australia (450 - 600nm wavelength range), and another located at the Subaru Telescope in Hawaii, USA (600 - 800 nm wavelength range). Both instruments have a novel fibre feed consisting of an integral field unit injecting light into a 2D grid of single mode fibres. This grid of fibres is then reformatted into a 1D array at the input of the spectrograph (consisting of the science fibres and a reference fibre capable of receiving a white-light or xenon reference source for simultaneous calibration). The use of single mode fibres frees RHEA from the issue of modal noise and significantly reduces the size of the optics used. In addition to increasing the overall light throughput of the system, the integral field unit allows for cutting edge science goals to be achieved when operating behind the 8.2 m Subaru Telescope and the SCExAO adaptive optics system. These include, but are not limited to: resolved stellar photospheres; resolved protoplanetary disk structures; resolved Mira shocks, dust and winds; and sub-arcsecond companions. We present details and results of early tests of RHEA Subaru and progress towards the stated science goals.
3

The SCExAO high contrast imager: transitioning from commissioning to science

Jovanovic, N., Guyon, O., Lozi, J., Currie, T., Hagelberg, J., Norris, B., Singh, G., Pathak, P., Doughty, D., Goebel, S., Males, J., Kuhn, J., Serabyn, E., Tuthill, P., Schworer, G., Martinache, F., Kudo, T., Kawahara, H., Kotani, T., Ireland, M., Feger, T., Rains, A., Bento, J., Schwab, C., Coutts, D., Cvetojevic, N., Gross, S., Arriola, A., Lagadec, T., Kasdin, J., Groff, T., Mazin, B., Minowa, Y., Takato, N., Tamura, M., Takami, H., Hayashi, M. 26 July 2016 (has links)
SCExAO is the premier high-contrast imaging platform for the Subaru Telescope. It offers high Strehl ratios at near-IR wavelengths (y-K band) with stable pointing and coronagraphs with extremely small inner working angles, optimized for imaging faint companions very close to the host. In the visible, it has several interferometric imagers which offer polarimetric and spectroscopic capabilities. A recent addition is the RHEA spectrograph enabling spatially resolved high resolution spectroscopy of the surfaces of giant stars, for example. New capabilities on the horizon include post-coronagraphic spectroscopy, spectral differential imaging, nulling interferometry as well as an integral field spectrograph and an MKID array. Here we present the new modules of SCExAO, give an overview of the current commissioning status of each of the modules and present preliminary results.

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