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Proceedings Paper

Optical object detection in paper improved by refractive index matching and mechanical treatment
Author(s): J. Saarela; S. Heikkinen; T. Fabritius; R. Myllylä
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Paper Abstract

Two different paper grades were tested with a clearing agent to measure how much mechanical smoothening can improve transparency inside paper. The paper grades were newsprint and supercalendered paper. The paper furnishes of both papers were alike, but the supercalendered paper was mechanically smoothened. Anise oil was used as the clearing agent, but similar measurements were also done with air and water. Black lines 8.5 μm to 281.1 μm wide were placed behind layers of cleared paper and transparency was measured with a microscope. When anise oil was the clearing agent, supercalendering improved transparent paper grammage from 139 g/m2 to 164 g/m2. With water the improvement was from 40 g/m2 to 51 g/m2. With air the improvement was not determinable. As a conclusion, it is recommended that paper is smoothened if it needs to be studied optically. Optical coherence tomography, for example, would benefit from this treatment.

Paper Details

Date Published: 5 June 2008
PDF: 8 pages
Proc. SPIE 7022, Advanced Laser Technologies 2007, 70221A (5 June 2008); doi: 10.1117/12.804109
Show Author Affiliations
J. Saarela, Univ. of Oulu (Finland)
S. Heikkinen, Univ. of Oulu (Finland)
T. Fabritius, Univ. of Oulu (Finland)
Univ. of Tsukuba (Japan)
R. Myllylä, Univ. of Oulu (Finland)


Published in SPIE Proceedings Vol. 7022:
Advanced Laser Technologies 2007

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