Nanometer-displacement detection of optically trapped metallic particles based on critical angle method for small force detection

Eiji Higurashi, Renshi Sawada, Takahiro Ito

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

We have developed a method of measuring the displacement of optically trapped metallic particles (10 μm in diameter) in water with nanometer resolution to detect small forces. Metallic particles were optically trapped in two dimensions by focusing a laser beam below the particle using an objective lens with a numerical aperture of 0.9. Displacement of a trapped metallic particle was detected using the light reflected from the particle based on the critical angle method. The lateral spring constant was estimated from the equipartition theorem to be on the order of 10-6 N/m and found to increase as the incident laser power increased. Consequently, a trapped metallic particle can be used to detect small forces (10-13 N).

Original languageEnglish
Pages (from-to)3068-3073
Number of pages6
JournalReview of Scientific Instruments
Volume70
Issue number7
DOIs
Publication statusPublished - Jan 1 1999
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Instrumentation

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