Machine vision based on-line microscopy improves process monitoringIn process monitoring applications information on the exact internal composition and quality of the ingredients at different stages of the process enables the systematic control of the process. In these analyses the objects are typically small particles dissolved in water or some other liquid material. On-line microscopy offers a potential solution for these applications. VTT Electronics develops a research environment for the evaluation of the performance of on-line microscopy in process monitoring applications. The environment consists of modular systems for the illumination, imaging and the manipulation of the sample material. For example, the straighforward implementation of several illumination arrangements (e.g. Köhler, dark field, telecentric) is possible in order to determine rapidly the best method for the application in question.  One example, of the use of
the machine vision based microscopy is experimental system for accurate
and reliable measurement of coloured ink particles in recycled pulp developed
in VTT Electronics. The system is able to measure automatically the number,
total area and size distribution of cyan, magenta, yellow and black coloured
ink particles. The system consists of a microscope, colour video camera,
PC with framegrabber and the image analysis software. The experimental
results were consistent with the order of samples, ie. samples taken earlier
in the de-inking process had more ink particles than the ones taken later.
Further more, the number, size distribution and overall area covered by
ink particles of different colours as measured with the experimental system
corresponded well with manual measurements. The speed of the analysis is
well suited for laboratory as well as sample based at-line analysis.
  Original (left) and segmented
image of a recycled pulp sample.
 Number of coloured ink particles at different stages of the de-inking process. In addition to the different analyses in pulp and paper industry, the potential applications of the on-line microscopy include at least process monitoring in chemical industry and condition monitoring based on particle analyses from lubricants or process water. Examples of such measurements are analyses of extenders of plastics and determination of impurities of mineral powders or molten plastics. For further information
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