A multispectral emitter was a Romulan technology used on some ships to create wave outputs at or about the frequency of light. In 2154, a Romulan drone ship had a hull lined with multispectral emitters that allowed it to create the holographic illusion of being several other ships, including Enterprise NX-01, the Kumari, and a Tellarite cruiser. (ENT: "Babel One") The Romulans used the ship and its ability to change appearance in an effort to create tension between the regional powers. (ENT: "United")