Atp laser optical contact tachometer dt 6236b atp dt 6236b p the atp dt 6236b is a optical contact tachometer for measuring speeds of rotating objects in rpm or for measuring surface speeds in meters per minute or feet per minute the high accuracy of the apt dt 6236b is achieved by combining cpu photoelectrical and laser techniques the ergonomic design of the apt dt 6236b makes the instrument comfortable to use p atp laser optical contact tachometer dt 6236b