Interfacial shape and contact-angle measurement of transparent samples with confocal interference microscopy

David G. Fischer, Ben Ovryn

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

A model has been developed that predicts the effective optical path through a thick, refractive specimen on a reflective substrate, as measured with a scanning confocal interference microscope equipped with a high-numerical-aperture objective. Assuming that the effective pinhole of the confocal microscope has an infinitesimal diameter, only one ray in the illumination bundle (the magic ray) contributes to the differential optical path length (OPL). A pinhole with finite diameter, however, allows rays within a small angular cone centered on the magic ray to contribute to the OPL. The model was incorporated into an iterative algorithm that allows the measured phase to be corrected for refractive errors by use of an a priori estimate of the sample profile. The algorithm was validated with a reflected-light microscope equipped with a phase-shifting laser-feedback interferometer to measure the interface shape and the 68° contact angle of a silicone-oil drop on a coated silicon wafer.

Original languageEnglish (US)
Pages (from-to)478-480
Number of pages3
JournalOptics Letters
Volume25
Issue number7
StatePublished - Apr 1 2000
Externally publishedYes

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rays
optical paths
microscopy
interference
microscopes
pinholes
silicones
numerical aperture
bundles
cones
interferometers
oils
illumination
wafers
scanning
silicon
estimates
profiles
lasers

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Interfacial shape and contact-angle measurement of transparent samples with confocal interference microscopy. / Fischer, David G.; Ovryn, Ben.

In: Optics Letters, Vol. 25, No. 7, 01.04.2000, p. 478-480.

Research output: Contribution to journalArticle

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