Extremely Large Telescope

Abstract:

We present a novel design of a fibre-fed high-resolution spectrograph (HRS hereafter) for WFMOS. WFMOS HRS is a multi-object spectrograph for studying the formation and evolution history of our Galaxy by measuring spectra of Galactic stars. In a 8m-class telescope, it aims to measure 1,500 stellar spectra simultaneously with spectral resolution between 25,000 and 40,000 in optical wavebands de.ned within 4000Å and 9000Å. For the HRS optical design, we have explored three disperser options : Volume Phase Holographic Grating (VPHGs), prism-immersed VPHG, and Echelle grating. Two camera designs have also been studied for the spectrograph camera optics, one tranmissive design and the other a Schmidt design. We also investigated a conjugate collimator design that allows two spectrographs to share a single grating so as to work as a single spectrograph.

Abstract:

The superb image quality that is predicted, and even demanded, for the next generation of Extremely Large Telescopes (ELT) presents a potential crisis in terms of the sheer number of detectors that may be required. Developments in infrared technology have progressed dramatically in recent years, but a substantial reduction in the cost per pixel of these IR arrays will be necessary to permit full exploitation of the capabilities of these telescopes. Here we present an outline and progress report of an initiative to develop a new generation of astronomical grade Cadmium Mercury Telluride (HgCdTe) array detectors using a novel technique which enables direct growth of the sensor diodes onto the Read Out Integrated Circuit large monolithic arrays. We present preliminary growth and design simulation results for devices based on this technique, and discuss the prospects for deployment of this technology in the era of extremely large telescopes.