It is the object of this Phase I and Phase II study to design, assemble, and bench test a commercial prototype fluorescence imaging system for use in endoscopic localization of in-situ cancer. This prototype instrument is to be based on the vast experience of the principal investigator and the consultant in endoscopic fluorescence imaging, and is directed at developing a commercially viable system. Previous research units do not lend themselves to direct commercialization due to cost, complexity, and difficulty in use. The instrument is based on the fluorescence and tumor localization properties of hematoporphyrin derivative (HpD), or its more purified form di-hematophorphyrin-ether (DHE). DHE is presently undergoing Phase III clinical trials directed at an NDA for uncontrolled clinical use. Phase I will emphasize characterization of the important parameters and components along with phantom and bench testing. Phase II will encompass a commerical system development for clinical testing under Phase III studies. If a reliable cost effective system can be developed, it will have a significant potential market in the early cancer localizing in the lung, bladder, stomach, cervix, and skin, among other cancers.