An optical apparatus and a manufacturing method using the optical apparatus are disclosed. The optical apparatus includes a stage supporting a substrate, first optical systems providing a first light onto the substrate, a gantry supporting the first optical systems to transfer them on the stage, and second optical systems disposed between the gantry and the stage and detecting displacement of the first optical systems. Each of the second optical systems includes a beam source generating a second light different with the first light, and sensor arrays for sensing the second light provided to the first optical systems to detect displacement of the first optical systems.