Minimum detectable displacement in near-field scanning optical microscopy

Fred F. Froehlich, Tom D. Milster

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


The probe-to-sample separation in near-field scanning optical microscopes can be regulated by a noncontact atomic shear force sensing scheme that allows simultaneous acquisition of optical and shear force images. We have measured the minimum detectable displacement that can be achieved with a scheme based on diffracting a focused laser beam from the vibrating probe. The minimum detectable displacement determines the smallest resolvable change in force acting on the probe. The measured shot-noise-limited value is 2.8×10 -3 Årms/Hz,and the practical sensitivity is limited by thermal vibration noise to 7×10-3 Årms/Hz. These values compare well with those calculated theoretically.

Original languageEnglish (US)
Pages (from-to)2254-2256
Number of pages3
JournalApplied Physics Letters
Issue number18
StatePublished - 1994

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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