Abstract
A new thermal lens microscope (TLM) was developed for single non-fluorescent molecule detection. The TLM, differential interference contrast thermal lens microscope (DIC-TLM) realizes background-free photodetection by interference and exploits phase contrast generated by absorption and thermal relaxation instead of refraction used in conventional TLMs. As a result, a background was reduced to 1/100 and gold nanoparticles (5 nm) were counted as pulse signals with extremely high signal-to-noise ratios (S/N=70). The signals are also recorded in a single molecule measurement. In addition, a precise determination will be possible by combining an extended-nanochannel. © 2009 CBMS.