The Periscope Optical Test Equipment (POTE) is designed for use with submarine periscopes. The POTE concept provides for a measurement of a specific parameter - rather than a comprehensive analysis - to determine if the periscope optical performance is satisfactory. The system design incorporates custom optics (reflecting the photographic use of submarine periscopes) in conjunction with a microcomputer - based image processor. Special fixturing was designed to allow for rapid installation and alignment aboard a submarine. The use of a single spatial frequency, a programmable criterion level and automatic self-checks are discussed.