Near-field scanning optical microscopy에 대한 설명, eNose에 대한 설명과 원리.
1. Explain the basic principle of the near-field scanning optical microscopy (NSOM)
2. What is an eNose? Please include, in your explanation, the basic principle and possible applications.
3. Find and read the article about “Millipede” Nanotechnology – The race to the bottom IEEE Spectrum March 2005 (www.spectrum.ieee.org) pp. 26 - 33.
For the last 100 years conventional far-field optical microscopy has been an indispensable tool both in research and for routine applications. Its lateral resolution is fundamentally limited by diffraction to approx. 200 nm. In order to circumvent this limit a new microscope, the scanning near-field optical microscope (SNOM or NSOM) was introduced in the early 1980s.
FIGURE 1: Schematic of near-field optical microscopy
The Scanning Near-Field Optical Microscope (SNOM) is a scanning probe microscope that allows optical imaging with spatial resolution beyond the diffraction limit. A nanoscopic light source, usually a fiber tip with an aperture smaller than 100 nm, is scanned very closed to the sample surface in the region called "optical near-field".
The achievable optical resolution is mainly determined by the aperture size of the optical probe and the probe-surface gap. A SNOM instrument must therefore feature:
a feedback system keeping the probe at constant distance from the surface. As a benefit, this allows to record the samples topography simultaneously
a high quality near-field probe