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Proceedings Paper

Influence of the projected grid pattern distortions on measurement accuracy for phase shift based 3D inspection
Author(s): Igor Dunin-Barkowski; Jae Seon Kim
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Paper Abstract

Recently 3D inspection tasks become more and more important, especially in electronic manufacturing industry segment in such areas as solder paste inspection, wafer bump inspection, ball grid array (BGA) and leadless packages inspection, pre- and post-reflow surface mount technology (SMT) board inspection and others, number of these tasks is rapidly growing. The main trend in these applications is that sizes of objects that are being inspected are decreasing down to tens of microns thus increasing requirements in measurement accuracy for inspection systems including increasing of both range and lateral resolutions. All these factors form strong demand for 3D measurement methods that could combine high resolution and accuracy with high-speed scan and measurement capabilities. That is why phase shift profilometry methods, based on projection of structured moire-like light pattern on object's surface and measurement of the resultant phase shift, are becoming more and more popular due to their efficiency, precision and robustness. To ensure these method's precision it is necessary to make the projected pattern perfectly sinusoidal and also having predefined grid pitch (period). These parameters are subjects for various distortions due to several factors. Among these factors there are variations of projector's working distance due to changes of objects position, grating distortions, non-sinusoidality of grating's transmission profile, grating pitch variations, etc. Compensation methods for neutralizing the influence of the above mentioned factors are presented in this paper along the experiment results based on 3D measurement head developed by authors for solder paste inspection utilization as well as simulation results.

Paper Details

Date Published: 6 December 2005
PDF: 7 pages
Proc. SPIE 6051, Optomechatronic Machine Vision, 60510P (6 December 2005); doi: 10.1117/12.648848
Show Author Affiliations
Igor Dunin-Barkowski, Synapse Imaging Co. (South Korea)
Jae Seon Kim, Synapse Imaging Co. (South Korea)

Published in SPIE Proceedings Vol. 6051:
Optomechatronic Machine Vision
Kazuhiko Sumi, Editor(s)

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