An apparatus and a method for aligning a loadport on a process machine are disclosed. The apparatus is constructed by a base plate, an alignment block mounted on the base plate, a light source and an optical detector. The alignment block is provided with an aperture extending longitudinally through the block, or formed in a T-shape extending both longitudinally and transversely through the block. The light source may be suitably a laser emission source, or a laser source that operates in a pulse mode. The diameter of the aperture provided in the alignment block should be sufficiently small, i.e. smaller than 5 mm, and preferably smaller than 3 mm.