We report a highly sensitive wide-�eld imaging technique for quantitative measurement of the
optical extinction cross-section �ext of single nanoparticles. The technique is simple and high-speed,
and enables simultaneous acquisition of hundreds of nanoparticles for statistical analysis. Using
rapid referencing, fast acquisition, and a deconvolution analysis, a shot-noise limited sensitivity down
to 0.4nm2 is achieved. Measurements on a set of individual gold nanoparticles of 5nm diameter
using this method yield �ext = (10:0 � 3:1)nm2, consistent with theoretical expectations, and well
above the background
uctuations of 0.9nm2
