Patent ID: 8842295

Claim:
A system comprising an object movable in relation to a reference system along at least two orthogonal first and second main movement axes; and a position-measurement device adapted to detect a position of the object in relation to the reference system, the position-measurement device including: at least two two-dimensional measuring standards; at least four first scanning units adapted to optically scan the measuring standards; at least four additional supplementary scanning units arranged along the first main movement axis between the four first scanning units; wherein at least one of the first scanning units is arranged along the first main movement axis at a first location, at least one of the first scanning units is arranged along the first main movement axis at a second location, at least one of the additional supplementary scanning units is arranged along the first main movement axis at a third location, and at least one of the additional supplementary scanning units is arranged along the first main movement axis at a fourth location; wherein the third location and the fourth location are located in between the first location and the second location, the third location and the fourth location being spaced apart in a direction of the first main movement axis; wherein at least one of the first scanning units is arranged along the first main movement axis at a fifth location, at least one of the first scanning units is arranged along the first main movement axis at a sixth location, at least one of the additional supplementary scanning units is arranged along the first main movement axis at a seventh location, and at least one of the additional supplementary scanning units is arranged along the first main movement axis at an eighth location; and wherein the seventh location and the eighth location are located in between the fifth location and the sixth location, the seventh location and the eighth location being spaced apart in a direction of the first main movement axis.