Noncontact near-field scanning optical microscopy imaging using an interferometric optical feedback mechanism

Hitoshi Shiku, Jeffrey R. Krogmeier, Robert C. Dunn

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


An interferometric optical feedback mechanism is explored for tip-sample distance control in near-field scanning optical microscopy. An optical signal, based on the interference between the light exiting the tip aperture and that reflecting off the sample surface, is used to implement a feedback scheme to regulate tip-sample distance. The noncontact nature of this feedback mechanism may provide greater flexibility in imaging soft or fragile samples. To characterize the performance of the optical feedback mechanism, images are analyzed of a calibration standard, fluorescently doped lipid monolayers, latex spheres, and fixed cells. Images taken of these samples using optical feedback and the standard tapping-mode feedback are comparable in quality. These samples also demonstrate the ability of optical feedback to follow both large and small height changes and accurately reflect the sample topography. In a nonscanning mode, the interferometric signal can be used to noninvasively probe small dynamic height changes of a sample with nanometric spatial resolution. Using a piezo ceramic bimorph to simulate sample movement, we show that nanometric height changes can be detected with millisecond time resolution. This may provide a unique way to probe protein conformational changes free of tip-sample interactions.

Original languageEnglish
Pages (from-to)2162-2168
Number of pages7
Issue number6
Publication statusPublished - 1999 Mar 16
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry


Dive into the research topics of 'Noncontact near-field scanning optical microscopy imaging using an interferometric optical feedback mechanism'. Together they form a unique fingerprint.

Cite this