The ATLAS (Airborne Terrestrial Applications Sensor) system is a 15-channel imager for remote sensing applications currently under development at the NASA Stennis Space Center. This paper describes the optical design of the scan head optics, which include the linescan mirror, Dall-Kirkham telescope, collimator, and three spectrometers. The sensor package has a 7.5-inch entrance aperture with a 2.0 mrad ifov, total field of view of 73 degrees, and scan rates adjustable in the range 6 - 50 rev/sec. Spectral coverage is provided in the visible and near infrared (VIS/NIR, 0.45 - 0.90 micrometers , 6 channels) using three spectrometers. The three spectrometers have a modular design for future applications growth. Design and specifications for the telescope, special dichroics, gratings, imaging lenses and other components for the spectrometers, will be described. Detector arrays for the three spectrometers, and built-in sources for radiometric calibration, will also be discussed. Finally, results of overall ATLAS systems performance analysis on optical throughput, SNR, NETD, etc, will be presented.