Abstract: The present invention relates to an optical scanning device for use in sawmills, to determine the severity and location of surface defects on lumber, for the purpose of grading and trimming, having a plurality of optical scanning means mounted to a frame and positioned above lumber transport means. The scanning means are adapted to scan at least one face of a predetermined segment of each board, and comprise a lens, means to convert an image resolved in the lens into electronic signals and means to transmit said signals to signal processing means adapted to assess surface defects on the board and determine a lumber grade of each board. The device may include means for rotating each board about its longitudinal axis to sequentially expose the longitudinal faces thereof to the scanning means.