The present invention provides a support stand. The support stand includes at
least one H-beam set between a light source of an exposure machine and an operating
machine of that to support an optical axis of the exposure machine, at least one
supporting element set on a first part of the H-beam, a signal emitter set on a
second part of the H-beam, and a signal receiver, receiving a signal sent from
the signal emitter, set on a third part of the H-beam. The signal emitter and the
signal receiver are used for detecting an optical axis shift.
