Share Email Print
cover

Proceedings Paper

Moire fringe method for the measurement of distortions of hot-embossed polymeric substrates
Author(s): Hayden K. Taylor; Zhiguang Xu; Shiguang Li; Kamal Youcef-Toumi; Yoon Soon Fatt; Duane S. Boning
Format Member Price Non-Member Price
PDF $14.40 $18.00

Paper Abstract

We present a way to identify distortions of transparent micro-patterned substrates using a desktop document scanner and a set of image processing routines. The method requires neither expensive optical equipment nor precise positioning of the part. It is therefore ideally suited to rapid process monitoring. A 5000-dpi imagesetter is used to print a square reference grid of lines having a known pitch ~100 μm. This reference pattern is used to produce a hard stamp that is subsequently embossed into a sheet of thermoplastic polymer. The pattern transferred to the polymer may include distortions resulting from contraction of the sheet after separation from the stamp. To measure these distortions, the embossed polymeric part is placed on a document scanner. The reference grid is laid on top of the part and rotated by hand until moire fringes are seen. At least two scans are made, each with a different relative reference-part rotation. For each scan, the orientation of the part relative to the reference grid may be arbitrarily chosen within an allowable range of a few degrees. These orientations may be extracted from the captured images, and, together with the moire fringes' orientations and spacings, provide enough information to obtain the part's distortions. Estimates of part strains may be improved, at the expense of measurement time, by capturing more images. The approach can detect isotropic shrinkage of the part with a strain resolution ~10-3.

Paper Details

Date Published: 3 October 2008
PDF: 9 pages
Proc. SPIE 7155, Ninth International Symposium on Laser Metrology, 715528 (3 October 2008); doi: 10.1117/12.814582
Show Author Affiliations
Hayden K. Taylor, Massachusetts Institute of Technology (United States)
Zhiguang Xu, Massachusetts Institute of Technology (United States)
Singapore Institute of Manufacturing Technology (Singapore)
Singapore-MIT Alliance (Singapore)
Shiguang Li, Singapore Institute of Manufacturing Technology (Singapore)
Singapore-MIT Alliance (Singapore)
Kamal Youcef-Toumi, Massachusetts Institute of Technology (United States)
Yoon Soon Fatt, Nanyang Technological Univ. (Singapore)
Duane S. Boning, Massachusetts Institute of Technology (United States)


Published in SPIE Proceedings Vol. 7155:
Ninth International Symposium on Laser Metrology

© SPIE. Terms of Use
Back to Top