| 摘要 |
An interferometer, e.g., a Z interferometer (43A, 43B) is used to measure first position information on a stage (WST). Simultaneously, a surface position measuring system, e.g., two Z heads (743, 763) is used to measure second position information on the stage (WST). The moving average of the differences between the first position information and the second position information is calculated for a predetermined measurement time to determine a coordinate offset. By using the coordinate offset, the reliability of the output signal of the surface position measurement system is verified. When the normality is confirmed, the stage (WST) is servo-controlled by using the sum of the first position information and the coordinate offset. By this hybrid servo control, control of the drive of the stage (WST) with both interferometer stability and Z-head precision is possible. |
