Locating system for use in vacuum

This invention is related to a locating system for use in vacuum for locating an object, including: an X-Y-theta platform capable of moving in X, Y, and theta directions, so as to locate the position and/or orientation of the object along the X, Y, and theta axes. The platform includes therein a rotating shaft for defining the theta degree; an elevating platform allowing vertical movement for locating the object along the Z axis; a transmission shaft, connected to and driven by the elevating platform and the X-Y-theta platform; a hermetically sealed chamber for providing the hermetically sealed space required by motions of the rotary shaft and the transmission shaft; and a vacuum chamber, for providing a vacuum space to allow the transmission shaft to move and to locate the object therein.