A comparison of five optical surface topography measurement methods

Marja Mettänen, Ulrich Hirn

    Research output: Contribution to journalArticleScientificpeer-review

    10 Citations (Scopus)
    603 Downloads (Pure)

    Abstract

    The results of optical surface topography measurement techniques have been questioned in the past because of possible measurement artifacts due to light penetration into the paper. We compared the topography measurement results from five optical techniques: laser profilometry, shape-from-focus, stripe projection, chromatic sensing, and photometric stereo. These techniques were tested on coated and uncoated papers with a PPS roughness range from 0.7 μm to 7.7 μm. We made the measurement results directly comparable by measuring exactly the same regions on the paper samples and registering the resulting topography maps. We then calculated the point-wise Pearson correlation between the maps at different wavelength bands to obtain quantitative values for the similarity of the measurement results at different structure sizes. The correspondences between the measured topography maps were also examined through multivariate linear regression and roughness indices evaluated at two different structure sizes. For rougher grades like office paper or sack paper, the topography measurements from the five measurement techniques showed corresponding results. For a moderately smooth lightweight coated (LWC) paper, the measured topographies agreed to some degree, and for smooth supercalendered (SC) and woodfree coated (WFC) papers, the agreement was poor. From the available data, it is impossible to tell which of the measurement techniques delivers the true surface topography of smooth papers.

    Original languageEnglish
    Pages (from-to)27-38
    Number of pages12
    JournalTAPPI Journal
    Volume14
    Issue number1
    Publication statusPublished - 1 Jan 2015
    Publication typeA1 Journal article-refereed

    Publication forum classification

    • Publication forum level 1

    ASJC Scopus subject areas

    • Media Technology
    • General Chemical Engineering
    • General Chemistry
    • Mechanical Engineering
    • General Materials Science

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