Using near-field scanning optical microscopy and finite difference time-domain modeling, scientists at Academia Sinica in Taipei, Taiwan, have investigated the propagation of light through a slit. Their findings confirm that the transmittance of s-polarized light is an order of magnitude higher than p-polarized because of the formation of a surface plasmon wave at the air-metal interface.The team employed a homebuilt microscope in the experimental section of the work to collect the 532-nm s- or p-polarized light from a 5-mW diode laser that passed through a 100-nm-wide slit in 200-nm-thick aluminum film. The simulations of the setup by the finite difference time-domain method verified the observations, as reported in the Dec. 2 issue of Optics Express.