Figure 1
From: Electronic Raman Scattering On Individual Semiconducting Single Walled Carbon Nanotubes

Schematic presentation of experimental geometry.
(a) The excitation laser is shed at an oblique angle α against the SWNT suspended on the open slit of the substrate. The scattered light is collected at normal direction with respect to the SWNT axis. (b) Schematic of the scattering geometry with respect to the nanotube direction.