Patent ID: 8760622

Claim:
A movable body apparatus, comprising: a movable body that moves in at least one axial direction along a predetermined plane; a first measurement device that includes a moving grating which is arranged on the movable body and to which a first measurement light is irradiated along an optical path that includes a first optical path that extends parallel to the one axial direction, a fixed grating which is arranged outside the movable body and has a periodic direction in the one axial direction and to which a diffracted light generated at the moving grating is irradiated, and a photodetection system which receives a diffracted light from the fixed grating via the moving grating, and that measures positional information of the movable body in the one axial direction; and a second measurement device that measures positional information of the movable body in the one axial direction, by irradiating a reflection surface arranged on the movable body with a second measurement light along a second optical path in the one axial direction, which is close to or overlaps with the first optical path, and receiving a reflected light from the reflection surface.