An object detection method and an object detection system, suitable for detecting moving object information of a video stream having a plurality of images, are provided. A first engine hanger is welded to a lower end of the lower frame such that an atmospheric air communicating hole formed in a side face of the first engine hanger communicates with the inside of the lower frame. A first set of reticle-deformation data is obtained by detecting the positions of at least some of the first set of reticle-position-measurement marks using an inspection device that is separate from the microlithography apparatus with which the reticle will be used for making lithographic exposures.