Fig. 3.

The dependence of spectra on optical configuration can be seen in recorded spectra from a single polystyrene sphere, approximately 10μm in size. Spectra were recorded using a 74X 0.65NA cassegrain objective and various condenser parameters, including a 15X 0.5NA cassegrain (green) and a 0.6NA germanium lens with a varying pupil to simulate changing NA. The NA of the germanium lens was artificially reduced using a pupil between 1mm and 11mm in diameter (black-red). Note the variation in recorded spectra and changes in chemical signal as the condenser NA is reduced.