Locating resin defects in slash pine billets using microwave imaging - A laboratory scale trial
This study investigated the potential of microwave imaging and acoustic tomography to detect the presence and location of resin shakes and/or resin streaks in Slash pine billets.
Two approaches were made using microwave technology. One was to use transmission tomography (microwave source and the detector are on opposite sides of the log, so that the signal is transmitted through the log). The second was to use microwave reflection (the source and detector are on the same side, so that a reflected signal is detected). In addition, 2D acoustic tomography was undertaken.
Locating resin streaks/shakes in freshly felled Slash pine logs with microwave sub-surface radar imaging has shown to be feasible in the instance where the resin defect breaches the heart/sapwood boundary. The detection of resin defects relies on observing discontinuities in the microwave reflection that normally results from the heart/sap boundary, therefore disruption to the reflected signal.