A trapped-particle near-field scanning optical microscope is constructed by use of submicrometer- or micrometer-sized metallic particles (gold and silver) to increase scattering efficiency. The image contrast of the evanescent-wave interference pattern on the surface of a prism upon total internal reflection, obtained with trapped gold particles of diameter 0.1 and 2µm , is improved by a factor of approximately 2 and 1.5, respectively, compared with that obtained with trapped polystyrene particles of similar size. The use of a 2-µm gold particle leads to image contrast that is approximately three times as great as that obtained with a 0.1-µm gold particle, and interference patterns of a subwavelength period are obtained in both cases.
© 1999 Optical Society of America
Min Gu and Pu Chun Ke, "Image enhancement in near-field scanning optical microscopy with laser-trapped metallic particles," Opt. Lett. 24, 74-76 (1999)