HIPO (High-speed Imaging Photometer for Occultations) is a special-purpose science instrument for use on SOFIA (the Stratospheric Observatory For Infrared Astronomy). HIPO covers the spectral range from the atmospheric UV cutoff at 0.3 microns to the silicon detector limit at 1.1 microns. It is a dual channel imaging photometer using 1Kx1K Marconi CCD47-20 frame transfer CCD detectors. In addition to its science applications, HIPO will be used extensively during performance testing of the SOFIA observatory. The optical design of the instrument includes optimized focal reducing optics for both blue and red channels, pupil viewing optics, and Shack-Hartmann test optics. The imaging performance is excellent, insuring that the instrument will provide a faithful representation of the SOFIA telescope's PSF (Point Spread Function) during test observations.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.