Heartwood detection for Scotch pine by fluorescence image analysis

Heartwood detection for Scotch pine (Pinus sylvestris) is possible via several different methods, such as X-ray and infrared cameras. X-ray systems are often very expensive and need huge modifications of sawmill equipment for implementation. Infrared cameras are more affordable but can only be applied for fresh samples with high water content. This article describes a novel imaging method for heartwood detection for Scotch pine, which is based on the fluorescence information emitted of pinosylvin type stilbene and its monomethyl ether. Fluorescence imaging is a low-cost method for measuring heartwood content in real time on an industrial line. The method is applicable for fresh and dried samples. This paper will show the results of fluorescence matrices of Scotch pine. Measurements were made with a bispectrometer system to obtain suitable wavelengths for the excitation and detection of fluorescence. A reliable measuring system is described, which is suited for on-line measurements on an industrial line. An algorithm will also be presented, which is useful for quantification of heartwood and sapwood.