Imaging the Universe in 3D with the VLT: The Next Generation Field   Spectrometer SPIFFI
  We present SPIFFI, the integral field spectrometer for the VLT. This instrument allows simultaneous observation of infrared spectra in more than 1000 image points of a two dimensional field. With its set of four gratings and a pixel scale that can be varied by a factor of ten, SPIFFI provides high flexibility, and at the same time offers the unique possibility of diffraction limited imaging spectroscopy at an 8m-class telescope, when fed by the adaptive optics system MACAO. We outline the scientific drivers for building such an instrument, the concept of image slicing, the optical design, and the implementation of SPIFFI. 
F. Eisenhauer, M. Tecza, S. Mengel, N. Thatte, C. Roehrle, K. Bickert,   J. Schreiber