Patent ID: 8724115

Claim:
An interferometer stage metrology system with interferometer mirror shape error recovery, comprising: an interferometer stage metrology system configured to interferometrically measure the position of a short-stroke wafer scanning stage of on an upper fast stage of a stacked stage wafer actuation system along at least one of a first axis, a second axis and a third axis, wherein the interferometer stage metrology system is further configured to interferometrically measure rotation of the short-stroke wafer scanning stage about at least one of the first axis, the second axis and the third axis, wherein the interferometer metrology system includes two or more interferometers for each axis, wherein a first interferometer mirror is disposed on a first surface of the short-stroke wafer scanning stage and a second interferometer mirror is disposed on a second surface of the short-stroke wafer scanning stage; a control system communicatively coupled to each of the interferometers of the interferometer metrology system, wherein the control system is configured to determine a shape error for the first interferometer mirror using two or more interferometer measurements from the two or more interferometers associated with the first interferometer mirror and a shape error for the second interferometer mirror using two or more interferometer measurements from the two or more interferometers associated with the second interferometer mirror.