Full-field chromatic confocal surface profilometry employing DMD correspondence for minimizing lateral cross talks

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

doi:10.1117/12.904881

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15 November 2011 Full-field chromatic confocal surface profilometry employing DMD correspondence for minimizing lateral cross talks

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

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Proceedings Volume 8321, Seventh International Symposium on Precision Engineering Measurements and Instrumentation; 832120 (2011) https://doi.org/10.1117/12.904881
Event: Seventh International Symposium on Precision Engineering Measurements and Instrumentation, 2011, Yunnan, China

Abstract

In the research, full-field chromatic confocal surface profilometry employing digital micro-mirror device (DMD) for spatial correspondence is proposed to minimize lateral cross talks between individual detection sensors. Although fullfield chromatic confocal profilometry is capable of enhancing measurement efficiency by completely removing timeconsuming vertical scanning operation, its vertical measurement resolution and accuracy are still severely affected by the potential sensor 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. Using the chromatic objective, the incident light is dispersed according to a pre-designed detection range from a few micrometers to several millimeters 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 (FWHM) 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, Hau-Wei Li, and Yi-Wei Chang "Full-field chromatic confocal surface profilometry employing DMD correspondence for minimizing lateral cross talks", Proc. SPIE 8321, Seventh International Symposium on Precision Engineering Measurements and Instrumentation, 832120 (15 November 2011); https://doi.org/10.1117/12.904881

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