Photothermal imaging of nanoparticles beyond the diffraction limit

In this paper, a full-field photothermal imaging technique, which does not require a time consuming scan as used in the conventional photothermal imaging system, is reported. Imaging on gold nanoparticles (70 nm) and a blue polystyrene bead (193 nm) were conducted and the experimental results demonstrate the visualization ability of the photothermal imaging technique on nanotargets that are below the diffraction limit. The photothermal imaging system can be operated in an ambient environment where vacuum is not required. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3600422]