Analytical Sciences

Standardization of Excitation Efficiency in Near-field Scanning Optical Microscopy

Tadashi MITSUI,* Yasutaka IMANAKA,* Kanji TAKEHANA,* Tadashi TAKAMASU,* Ken NAKAJIMA,** and Jeongyong KIM***

*Nanophysics Group, Quantum Dot Research Center, National Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0003, Japan
**WPI Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
***Department of Physics, University of Incheon, 12-1 Songdo-Dong, Yeonsu-Gu, Incheon 406-772, Korea

Near-field scanning optical microscope (NSOM or SNOM) is a form of scanning probe microscope (SPM), which is used to observe the optical properties of a sample surface with a nanometer-scale spatial resolution. Since the near-field light strongly interacts with the sample surface, or with nanometer-scale objects on the substrate’s surface, NSOM is advantageous to excite only the vicinity of a sample surface. From the view point of surface chemical analysis, a discussion about the light energy concentration within a nanometer-scale region, and an estimation of its efficiency are indispensable for accurate measurements of the optical properties in a nanometer-scale region. In this paper, we describe the concept, the cautions and the general guidelines of a method to measure the excitation efficiency of aperture-type NSOM instruments.

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