3D: The next generation near-infrared imaging spectrometer

The new MPE near infrared imaging spectrometer 3D represents a new generation of astronomical instrumentation. It is based on a 256(2) NICMOS-3 Rockwell array and can simultaneously obtain 256 H- or K-band spectra at R=1100 or 2100 from a square 16x16 pixel field on the sky. Typical pixel scales are 0.3('')/pixel or 0.5('')/pixel. 3D is a combination of a novel image slicer and a liquid nitrogen cooled long slit spectrometer. It includes high definition on-axis lens optics, a high efficiency directly ruled KRS-5 grism as well as a cold closed-loop piezo-driven tilt mirror allowing full spectral sampling. The instrument efficiency including detector is 15%. Combining the advantages of imaging and spectroscopy increases the observing efficiency on key astronomical objects (e.g. galactic nuclei) by such a large factor over existing grating or Fabry-Perot spectrometers that subarcsecond near-IR spectroscopy of faint Seyferts, starbursts, quasars, or distant galaxy clusters becomes feasible for the first time with 4m-class telescopes. As a portable instrument 3D has already been successfully deployed on several 2 and 4m-class telescopes.