Various systems for measurement of a specimen are provided. One system includes a first optical subsystem, which is disposed within a purged environment. The purged environment may be provided by a differential purging subsystem. The first optical subsystem performs measurements using vacuum ultraviolet...http://www.google.de/patents/US7564552?utm_source=gb-gplus-sharePatent US7564552 - Systems and methods for measurement of a specimen with vacuum ultraviolet light
