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Optical Engineering

Full-field chromatic confocal surface profilometry employing digital micromirror device correspondence for minimizing lateral cross talks
Author(s): Liang-Chia Chen; Yi-Wei Chang; Hau-Wei Li
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Paper Abstract

Full-field chromatic confocal surface profilometry employing a digital micromirror device (DMD) for spatial correspondence is proposed to minimize lateral cross-talks between individual detection sensors. Although full-field chromatic confocal profilometry is capable of enhancing measurement efficiency by completely removing time-consuming vertical scanning operation, its vertical measurement resolution and accuracy are still severely affected by the potential sensor lateral cross-talk problem. To overcome this critical bottleneck, a DMD-based chromatic confocal method is developed by employing a specially-designed objective for chromatic light dispersion, and a DMD for lateral pixel correspondence and scanning, thereby reducing the lateral cross-talk influence. Using the chromatic objective, the incident light is dispersed according to a pre-designed detection range of several hundred micrometers, and a full-field reflected light is captured by a three-chip color camera for multi color detection. Using this method, the full width half maximum of the depth response curve can be significantly sharpened, thus improving the vertical measurement resolution and repeatability of the depth detection. From our preliminary experimental evaluation, it is verified that the ±3σ repeatability of the height measurement can be kept within 2% of the overall measurement range.

Paper Details

Date Published: 15 May 2012
PDF: 11 pages
Opt. Eng. 51(8) 081507 doi: 10.1117/1.OE.51.8.081507
Published in: Optical Engineering Volume 51, Issue 8
Show Author Affiliations
Liang-Chia Chen, National Taiwan Univ. (Taiwan)
Yi-Wei Chang, National Taipei Univ. of Technology (Taiwan)
Hau-Wei Li, National Taipei Univ. of Technology (Taiwan)

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