title: Large-area and high-resolution distortion measurement based on Moiré fringe method for hot embossing process.
abstract: A Moiré fringe approach is developed to identify simultaneously the global and local distortions in hot-embossed polymeric samples. A square grid pattern with a pitch of 63.5 microm is hot-embossed on the polymer substrate. When a reference grid, a polymeric film with the same pattern, is placed on top of the sample, a Moiré fringe pattern is observed and recorded by a document scanner. The deviation of the intersections of the fringes from their ideal positions presents the residual distortion in the sample. With different sample-reference rotation angles eight images are acquired for the same sample to achieve the optimal result by a data fitting technique. The validity of this method is proved by the self-consistency of the results from the eight images. To the best of our knowledge, this is the first time distortion quantification has been achieved both in a large area up to that of a scanner and with a high resolution at the level of 1 microm. Furthermore, we do not use any expensive instrument, nor need to measure the sample-reference rotation angle or position the sample precisely, and the process is run automatically by a computer instead of manual operation.
authors.affiliation: Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
authors.forename: Zhiguang
authors.initials: Z
authors.lastname: Xu
authors.forename: Hayden K
authors.initials: HK
authors.lastname: Taylor
authors.forename: Duane S
authors.initials: DS
authors.lastname: Boning
authors.forename: Soon Fatt
authors.initials: SF
authors.lastname: Yoon
authors.forename: Kamal
authors.initials: K
authors.lastname: Youcef-Toumi