Abstract
Single molecule detection is an indispensable technology for analyses using small space. Previously, we developed a differential interferential contrast thermal lens microscope (DIC-TLM) for counting of single nonfluorescent molecules, while the target molecules must have absorption in visible range. In this paper, UV excitation was introduced into the DIC-TLM toward single molecule detection of nonlabeled proteins. In particular, a DIC optical system was designed and developed for UV excitation and its principle was verified. In addition, the performance of the UV excitation DIC-TLM was evaluated by counting metallic nanoparticles.