SPIFFI: a high-resolution near-infrared imaging spectrometer

Matthias Tecza; Niranjan A. Thatte; Alfred Krabbe; Lowell E. Tacconi-Garman

doi:10.1117/12.317264

21 August 1998 SPIFFI: a high-resolution near-infrared imaging spectrometer

Matthias Tecza, Niranjan A. Thatte, Alfred Krabbe, Lowell E. Tacconi-Garman

Proceedings Volume 3354, Infrared Astronomical Instrumentation; (1998) https://doi.org/10.1117/12.317264
Event: Astronomical Telescopes and Instrumentation, 1998, Kona, HI, United States

Abstract

SPIFFI is an integral field spectrograph with an HAWAII array that enables us to simultaneously take near IR spectra of 1024 spatial pixels in a hexagonal field of view on the sky. It can be used on 4 to 8 meter class telescopes with a maximum pixel scale of 0.5 arcsec and with adaptive optics pixel scales, Nyquist sampling the point spread function of the telescope. A fiber bundle of 1024 silica/silica fibers rearranges the 2D field of view into the 1D entrance slit of the spectrometer. A novel technique involving flared fibers is used to achieve a high filling factor and coupling efficiency. Each fiber tip in the bundle is flared to increase the fiber core diameter by a factor of 15. The tapered end is polished to form a spherical micro-lens with a hexagonal cross-section to couple light into the fiber core. Apart from yielding a high coupling efficiency and a high geometrical filling factor, the monolithic micro- lens/fiber system can be used at a working temperature of 77K without loosing positioning accuracy. The spectrometer optics is achromatic from 1.1 to 2.5 microns and use four reflection gratings on a wheel as dispersing elements with a resolving power from 2000 to 4500. The fore-optics includes the filter wheel, the cold pupil stop and a scale changing mechanism to switch between three different image scales according to observing and seeing conditions. The spectrometer collimator is a f/4.3 three lens achromat, the spectrometer camera is a f/1.2 folded Schmidt camera. The optical design of the spectrometer is distortion free to get straight, equidistant spectra that match the columns of the detector, thus minimizing cross-talk form adjacent spectra to less than 5 percent.

Citation Download Citation

Matthias Tecza, Niranjan A. Thatte, Alfred Krabbe, and Lowell E. Tacconi-Garman "SPIFFI: a high-resolution near-infrared imaging spectrometer", Proc. SPIE 3354, Infrared Astronomical Instrumentation, (21 August 1998); https://doi.org/10.1117/12.317264

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