Waltham, MA-based PerkinElmer (NYSE:PKI), a provider of research technologies and diagnostics, has acquired VisEn Medical for an undisclosed sum, according to the companies. Bedford, MA-based VisEn, which makes in vivo fluorescence imaging products, was co-founded in 2000 by Ralph Weissleder, the director of the Center for Systems Biology at Massachusetts General Hospital, and company CEO Kirkland Poss. Poss was not immediately available for comment this morning. VisEn’s venture backers include Cambridge, MA-based Flagship Ventures and Merck Capital Ventures. Ed Kania, co-founder and managing partner of Flagship, was the chairman of VisEn.