GOLD-BEAD SCANNING NEAR-FIELD OPTICAL MICROSCOPE WITH LASER-FORCE POSITION CONTROL

We have developed a scanning near-field optical microscope with an opt ically trapped metallic particle that has a small diameter compared to the wavelength of visible light. In this microscope we employed spot illumination to enhance the intensity of light scattered from a probe particle so we could reduce the diameter of the probe particle to 40 n m. We detected slight irregularities of the surface of the cover glass near 10-nm depth. Also, we observed gold colloidal particles on the s urface of the cover glass. (C) 1997 Optical Society of America.