Abstract: A detection unit comprising a manipulator, a imaging unit, a light beam irradiation unit and a computing unit, the imaging unit and the light beam irradiation unit are provided on a manipulator. The detection apparatus includes a horizontal imaging plane, which includes an optical axis of the imaging unit, and a vertical imaging plane, which includes the optical axis of the imaging unit and 1) a projection of a light beam from the light beam irradiation unit on the horizontal imaging plane and 2) a projection of a light beam from the light beam irradiation unit on the vertical imaging plane respectively form an intersecting angle with the optical axis of the imaging unit.