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- Nilsson, Carl Magnus, 1971-, et al.
(author)
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Application of optical spectroscopy to paper production
- 1999
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In: Optical measurement systems for industrial inspection. - Bellingham, Washington : SPIE - International Society for Optical Engineering. - 0819433101 ; , s. 318-325
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Conference paper (peer-reviewed)abstract
- Fluorescence from paper following excitation by either ultraviolet or visible light gives information on the chemical composition of the paper. This can be used for on-line monitoring of the paper during production. Such measurements can be performed non-intrusively at sampling rates high enough to give a sub-millimetre resolution at paper webs moving at velocities higher than 20 metres per second. Two types of fluorescence meters, operating at different wavelengths, have been constructed. Together with an optical speedometer they have been tested at newsprint producing paper mills. A fluorescence based method for scanning cross-directional newsprint profiles in the laboratory has been developed. From these measurements the relative shrinkage of the paper during drying can be calculated using time-frequency analysis.
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| 2. |
- Nilsson, Carl Magnus, et al.
(author)
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Study of pigment and optical response distributions in newsprint
- 1998
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In: Proceedings of the Technical Association of the Graphic Arts, TAGA. - Rochester, NY : Technical Association of the Graphic Arts. ; , s. 737-748
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Conference paper (peer-reviewed)abstract
- The quality of the printed screen dots is one of the critical factors that determine the over all quality of a printed halftone image. In this paper the spatial distribution of pigment is recorded and its relation to optical response and local paper grammage in printed screen dots on newsprint is analyzed. It is shown that light scattering inside the paper structure to some extent hide large irregularities in the pigment distribution. It is also shown that a hole in a screen dot will be optical mitigate by the paper structure as a result of multiple light scattering inside the bulk. We also show experimentally the hue shift in the border zone of the screen dot. A halo of light around the pigment area, which shifts from cyan towards green, has been determined around a cyan screen dot. Influence from the cyan pigment can be spotted in the optical response up to a distance of at least 20 μm from the measured pigment particle.
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