One embodiment provides a method for identifying a target object of a pipe wall, including: positioning a pipe inspection robot within a pipe; emitting, using a terahertz (THz) beam source of the pipe inspection robot, a laser beam towards a target object; receiving, using a THz receiver of the pipe inspection robot, THz data related to the target object; analyzing, using a processor, the THz data; and determining, based on the analyzing, an identity of the object. Other aspects are described and claimed.