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21 March 1997 New design for integral field spectroscopy with 8-m telescopes
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Proceedings Volume 2871, Optical Telescopes of Today and Tomorrow; (1997)
Event: Optical Telescopes of Today and Tomorrow, 1996, Landskrona/Hven, Sweden
I propose a new design of integral field unit (IFU) for two- dimensional area spectroscopy. The unit acts as a coupler between the telescope and spectrograph to reformat a square or rectangular field into a long slit. In addition to providing good transmission, it avoids the geometrical losses inherent in previous designs based on fiber optics, lens array re- imaging and image slicing. The proposed design is a new type of image slicer in which the original two-dimensional image is sliced into narrow sub-images that are re-imaged side by side to form a long one-dimensional image at the spectrograph input. The new design is much more compact than previous designs making it easier to insert in the front of a spectrograph without any modification to the spectrograph support system. The design uses much smaller optics than previous designs. The small number of reflections -- 4 to 6 depending on the telescope focal ratio -- and the smaller instrument size, which simplify the cooling of the instrument, makes the design well suited for infrared spectroscopy. The application of this design to 8-m telescopes and its use with adaptive optics in the optical and infrared is discussed, particularly with respect to the multi-object spectrographs of the Gemini telescopes project. In this case, the proposed design gives a field of 8.3' by 11.4' along with a background field of 2.6' by 3.6' with a spatial resolution of 0.09' by 0.16' and roughly 1200 spectral resolution elements in each spectrum. The spatial resolution is well suited to images produced by the Gemini telescopes in tip/tilt mode (typically FWHM approximately 0.3' in 10th percentile seeing) and with higher order adaptive optics. This design is also applicable to 4-m telescopes with -- or without-- adaptive optics. The possibility of inserting such an instrument in front of existing spectrographs is discussed.
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Robert Content "New design for integral field spectroscopy with 8-m telescopes", Proc. SPIE 2871, Optical Telescopes of Today and Tomorrow, (21 March 1997);

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