Internal Decay Detection
Where Visual Tree Assessment methods identify possible internal decay, SJ Stephens Associates use a range of internal decay detection devices, but most frequently:-
Digital microprobe: This measures the resistance to penetration to a 1mm probe rotating at high speed. Data is fed to a PC which produces a graph showing the hardness of wood along the path of the drill, showing the extent of decay.
Picus Sonic Tomograph: Sonic sensors strapped around the tree record the speed of sound waves traveling between them. Since sound wood is a better sound conductor, this data can produce an image on a PC showing areas of decay.