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Optical Engineering

Scanning dimensional measurement using laser-trapped microsphere with optical standing-wave scale
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Paper Abstract

We propose a laser trapping-based scanning dimensional measurement method for free-form surfaces. We previously developed a laser trapping-based microprobe for three-dimensional coordinate metrology. This probe performs two types of measurements: a tactile coordinate and a scanning measurement in the same coordinate system. The proposed scanning measurement exploits optical interference. A standing-wave field is generated between the laser-trapped microsphere and the measured surface because of the interference from the retroreflected light. The standing-wave field produces an effective length scale, and the trapped microsphere acts as a sensor to read this scale. A horizontal scan of the trapped microsphere produces a phase shift of the standing wave according to the surface topography. This shift can be measured from the change in the microsphere position. The dynamics of the trapped microsphere within the standing-wave field was estimated using a harmonic model, from which the measured surface can be reconstructed. A spherical lens was measured experimentally, yielding a radius of curvature of 2.59 mm, in agreement with the nominal specification (2.60 mm). The difference between the measured points and a spherical fitted curve was 96 nm, which demonstrates the scanning function of the laser trapping-based microprobe for free-form surfaces.

Paper Details

Date Published: 19 June 2017
PDF: 9 pages
Opt. Eng. 56(6) 064103 doi: 10.1117/1.OE.56.6.064103
Published in: Optical Engineering Volume 56, Issue 6
Show Author Affiliations
Masaki Michihata, The Univ. of Tokyo (Japan)
Shin-ichi Ueda, Osaka Univ. (Japan)
Satoru Takahashi, The Univ. of Tokyo (Japan)
Kiyoshi Takamasu, The Univ. of Tokyo (Japan)
Yasuhiro Takaya, Osaka Univ. (Japan)

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