INTERFEROMETER SYSTEM AND LITHOGRAPHIC APPARATUS COMPRISING SUCH A SYSTEM

摘要

The system has several X and Y measuring axes cooperating with X and Y measuring mirror on object (WH). The system has one Z measuring axis (MAX7 and 8) extending partly in an XY plane and cooperating with Z measuring mirrors (R'3 and 4) on object, and Z reflectors (164 and 168). Using this simple mechanism a larger number of more accurate and reliable measurements are performed with the system.