Exoplanets and Stellar Physics

Abstract:

When commissioned in November 2008 at the Palomar 200 inch Hale Telescope, the Oxford SWIFT I&z band integral field spectrograph, fed by the adaptive optics system PALAO, provided a wide (3x) range of spatial resolutions: three plate scales of 235 mas, 160 mas, and 80 mas per spaxel over a contiguous field-of-view of 89x44 pixels. Depending on observing conditions and guide star brightness we can choose a seeing limited scale of 235 mas per spaxel, or 160 mas and 80 mas per spaxel for very bright guide star AO with substantial increase of enclosed energy. Over the last two years PALAO was upgraded to PALM-3000: an extreme, high-order adaptive optics system with two deformable mirrors with more than 3000 actuators, promising diffraction limited performance in SWIFT's wavelength range. In order to take advantage of this increased spatial resolution we upgraded SWIFT with new pre-optics allowing us to spatially Nyquist sample the diffraction limited PALM-3000 point spread function with 16 mas resolution, reducing the spaxel scale by another factor of 5x. We designed, manufactured, integrated and tested the new pre-optics in the first half of 2011 and commissioned it in December 2011. Here we present the opto-mechanical design and assembly of the new scale changing optics, as well as laboratory and on-sky commissioning results. In optimal observing conditions we achieve substantial Strehl ratios, delivering the near diffraction limited spatial resolution in the I&z bands. © 2012 SPIE.

Abstract:

HARMONI is an integral field spectrograph working at visible and near-infrared wavelengths, over a range of spatial scales from ground layer corrected to fully diffraction-limited. The instrument has been chosen to be part of the first-light complement at the European Extremely Large Telescope (E-ELT1). This paper describes the engineering technology development being undertaken at the UKATC and Oxford to support E-ELT HARMONI2 instrument in its pre-phase-B stage. This includes the description of technology demonstrators for a tracking optical de-rotator to be located within the instrument vacuum vessel, a cryogenic shutter and a compact thermally compensating lens mount system. In addition the material testing facilities available at the UKATC are described which will enable the measurement of material and bolted joint thermal conductivities to 4K and friction/wear properties of material combinations to 20K. This work is undertaken to improve the instrument performance and reduce technical, cost and schedule risk. © 2012 SPIE.