Abstract: A method of aligning an optical system and an optical system incorporating the method. A hologram element is installed in the optical system so that test beams diffracted by the hologram element travel along a same optical path as test beams incident on the optical system. Alignment errors in the optical system are measured using interference patterns formed on an image surface by test beams returned from the optical system and reference beams. At least one optical element of the system is aligned using measurements calculated from the interference patterns. The optical system may provide for temporarily installing the hologram element to perform the measurements or the optical system may be constructed with a hologram formed on any optical element which may require alignment. A direction and a magnitude of any misalignment are determinable based on an appearance of the pattern and a number of circles in the pattern, respectively.