Measurements of the diffuse reflection of various samples of softwood were made over the wavelength range 380–1040 nm to determine if certain types of defect, such as strains, can be distinguished by reasonably straight forward optoelectronic means. Healthy specimens of spruce, fir, and pine were tested, followed by specimens from the same wood species which were disfigured by brown stain, rot, heart stain, blue beetle stain, and white speck. Samples were measured at a single angle of incidence, and no attempt was made to obtain the absolute value of the diffuse reflectivity. The results showed that there were significant differences between clear and stained wood, with sufficient spectral difference between different types of defect that allow automated optoelectronic sorting of the wood according to the specific type of stain present.
© 1989 Optical Society of America
K. D. Klapstein, F. L. Weichman, Will N. Bauer, and D. J. Kenway, "Optical characteristics of wood stains and rot," Appl. Opt. 28, 4450-4452 (1989)