Full-field chromatic confocal surface profilometry employing digital micromirror device correspondence for minimizing lateral cross talks

Liang-Chia Chen; Yi-Wei Chang; Hau-Wei Li

doi:10.1117/1.OE.51.8.081507

15 May 2012 Full-field chromatic confocal surface profilometry employing digital micromirror device correspondence for minimizing lateral cross talks

Liang-Chia Chen, Yi-Wei Chang, Hau-Wei Li

Author Affiliations +

Optical Engineering, Vol. 51, Issue 8, 081507 (May 2012). https://doi.org/10.1117/1.OE.51.8.081507

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.

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Liang-Chia Chen, Yi-Wei Chang, and Hau-Wei Li "Full-field chromatic confocal surface profilometry employing digital micromirror device correspondence for minimizing lateral cross talks," Optical Engineering 51(8), 081507 (15 May 2012). https://doi.org/10.1117/1.OE.51.8.081507

Published: 15 May 2012

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