| 摘要 |
A reference plate (RFM) formed with at least one pin hole-like pattern is fixed on a mask stage (RST) moving with a mask (R) held thereon. This arrangement makes it possible to measure the wave front aberration of a projection optical system without using special measuring mask by, for example, mounting a wave front measuring unit (80) suitable for mounting on a substrate stage (WST), illuminating the reference plate with a lighting system (IOP), and receiving a spherical wave produced by the pin hole-like pattern at the wave front measuring unit via the projection optical system (PL). Therefore, the wave front aberration of the projection optical system can be measured simply and at a desired timing, the projection optical system can be quality-controlled satisfactorily, and thereby a mask pattern can be transferred onto a substrate accurately by using the projection optical system subjected to a satisfactory quality control.
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