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Generating high-precision grayscale line profiles using DLP at maximum speed
Author(s): Roland Höfling; Frank Leischnig; Sören Gärtner; Petra Aswendt
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Paper Abstract

Using DLP® projection for 3D surface measurement is well established and very high-speed recording has been reported using binary structured light patterns. Advanced 3D measuring solution adopt phase shifting technology that yields higher data quality and increases the robustness of the inspection systems. Phase shifting requires the projection of precise sinusoidal patters. DLP chips produce native binary intensity modulation patterns and the grayscale output is typically realized by time averaging of the binary bit planes using pulse width modulation. That way, very precise grayscale line profiles can be projected but the pattern rates do not exceed 1200 fps substantially. This paper describes a novel methodology for precise grayscale line projection with up to 10-bit gray values and pattern frequencies that correspond to the maximum DLP pattern refresh rate. The basic principle of this new approach has been verified analyzing phase shifting pattern sequences recorded by an integrated camera. Precise 8-bit line profiles have been generated and the maximum of 50,000 profiles per second can be achieved with partial use of the DLP micro-mirror array. Experimental results are presented that are not only promising for future use in 3D surface inspection but have potential for other areas of industrial DLP applications as well.

Paper Details

Date Published: 4 March 2019
PDF: 8 pages
Proc. SPIE 10932, Emerging Digital Micromirror Device Based Systems and Applications XI, 109320H (4 March 2019); doi: 10.1117/12.2506881
Show Author Affiliations
Roland Höfling, ViALUX GmbH (Germany)
Frank Leischnig, ViALUX GmbH (Germany)
Sören Gärtner, ViALUX GmbH (Germany)
Petra Aswendt, ViALUX GmbH (Germany)

Published in SPIE Proceedings Vol. 10932:
Emerging Digital Micromirror Device Based Systems and Applications XI
Michael R. Douglass; John Ehmke; Benjamin L. Lee, Editor(s)

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