Beam alignment system

A beam alignment system having a source for producing a first beam of electromagnetic radiation considered an alignment or reference beam, a source for producing a second beam of electromagnetic radiation to be aligned with the first beam and pair of rotating mirrors capable of being optically interposed at different times across the optical path of the first and second beams. The axes of rotation of the pair of mirrors are transverse to each other in order to enable each mirror to provide alignment information about the beams with respect to two different planes. The alignment information is indicative of a time difference between the reception by a first detector of the reflected first beam and the reflected second beam from the first mirror and a time difference between the reception by a second detector of the reflected first beam and the reflected second beam from the second mirror. These time differences are utilized to provide signals which are used to adjust the position of the source for the second beam in order to bring the second beam into alignment with the first beam in two different planes.