Near-field Optical Microscopy and its Recent Advances: High Speed Imaging and Broadband Measurements
- Joint Online Seminar
- Date: Feb 28, 2022
- Time: 09:00 AM (Local Time Germany)
- Speaker: Dr. Takuyuki Umakoshi
- Osaka University, Department of Applied Physics
- Host: Takashi Kumagai

We
have been continuing for further developments. At the end of the talk,
we will discuss future perspective of these techniques.
In this talk, we introduce some unique aspects of the near-field optical
microscopy through developments that we recently made in this
technique. Focusing on not spatial resolution but temporal resolution,
we demonstrated high-speed near-field optical imaging [1]. The imaging
speed is mostly limited by slow scanning of either a tip or a sample,
which usually takes several minutes to take an image at least. By
introducing the high-speed atomic force microscope technique, we
achieved near-field fluorescent imaging within a few seconds.
Furthermore, we developed a plasmon nanofocusing technique to extend the
spectral range in the near-field optical microscopy [2]. Because
near-field light is often generated through plasmonic resonant
oscillation at a metallic tip, in addition to some technical
difficulties, the spectral range is limited within a certain width
around the plasmon resonance wavelength. We created broadband near-field
light at a metallic tip through plasmon nanofocusing, which is based on
propagation, not resonance, of plasmons. We further exploited it for
super-resolution scattering spectral imaging of carbon nanotubes.
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