CAMBRIDGE, England, Aug. 29 -- Cambridge Display Technology (CDT), a researcher and commercial technology developer of light-emitting polymers (LEPs), announced that it has been selected to develop a prototype handheld LEP display for the National Imagery and Mapping Agency (NIMA), through the National Technology Alliance Program.    The prototype handheld tactical device will use a red/near-infrared(R/NIR) monochrome LEP display. This display is designed to be easily viewed during normal daylight and night time operations as well as optionally viewed only with the use of night vision goggles, offering an important performance improvement in reducing the probability of detection.