Applications » Area Profile Measurement of Paper Surfaces
Accurate determination of surface parameters
Identification of periodic surface structures
Automation of measurement process
The printing process is the point at which a message is applied to media and made visible to the end users. It is important that the paper surface, whether it is used in a newspaper, book, coated magazine stock or paperboard be of good quality that the printing process will be effective and give the desired results. The types of requirements are ink absorption and the ability to apply graphics so that the paper surface roughness does not show thru. Finding a measuring solution to characterize the paper surface can be subjective and not always providing accurate, repeatable results. This paper will provide one measurement solution that will provide tools to effectively measure the surface characteristics of paper.
Both measurement and data analysis may run as part of automated sequence of steps setup as a list of system commands or by performing measurement and evaluation steps manually in a teaching mode. Use of a template guarantees identical evaluation conditions for each surface measured.
Standard roughness parameter values may be calculated for a line profile extracted from an area profile. Area roughness values may also be determined which characterize a surface with higher consistency. The Abbot Bearing Curve profile shows the proportion of measuring points whose heights lie above a particular height. The horizontal line lying in a reference plane parallel to the average area profile height may be positioned at any level within the profile at which the load bearing area is then calculated and displayed.
For a paper surface, the load bearing area determines the contact between the paper and printing roller, thereby strongly influencing the expected print quality.
The volume of material protruding through this imaginary reference plane and of empty space under the plane is given, allowing the volume determination of an indentation or protrusion when surrounded by a reference surface.
Both a line and area profile may be Fourier transformed, resulting either in a line power spectrum or a 2 dimensional power spectrum revealing quantative information on the spatial frequency components of the profile. The longer wavelength components determine the "form", of the surface, the middle wavelengths "waviness" and the shorter wavelengths it's "roughness". Autocorrelation helps identify periodic structures within a profile, correlation peaks clearly showing the wavelength of periodic surface structures. Slope distribution is an important parameter when considering frictional properties. An asymmetrical distribution, for example, indicates the predominance of profile slope at a particular spatial orientation leading to differences in frictional properties dependent on the direction of relative surface displacement.
Embedded structures in paper, hardly visible to the eye may be detected using the Solarscan measuring system. For example the impressions left on a paper surface by writing or the analysis of water marks are of particular interest in the field of forensic science.
The Solarscan measuring station equipped with a Chromatic Confocal sensor represents a cost-effective general purpose measuring system, offering high accuracy and a measurement speed far in excess of conventional mechanical stylus measuring systems. Solarius surface measurement software program Solarmap provides a comprehensive range of easily accessible analytical functions.