Affiliation: | 1.Unit of Measurement Technology, University of Oulu, P.O.Box 127, 87400, Kajaani, Finland ;2.Valmet Automation Inc., Elektroniikkatie 9, 90590, Oulu, Finland ;3.Optoelectronics and Measurement Techniques Unit, University of Oulu, P.O.Box 4500, 90014, Oulu, Finland ; |