Various systems for measurement of a specimen are provided. One system includes an optical subsystem configured to perform measurements of a specimen using vacuum ultraviolet light and non-vacuum ultraviolet light. This system also includes a purging subsystem that is configured to maintain a purged environment around the optical subsystem during the measurements. Another system includes a cleaning subsystem configured to remove contaminants from a specimen prior to measurement. In one embodiment, the cleaning subsystem may be a laser-based cleaning subsystem that is configured to remove contaminants from a localized area on the specimen. The system also includes an optical subsystem that is configured to perform measurements of the specimen using vacuum ultraviolet light. The optical subsystem is disposed within a purged environment. In some embodiments, the system may include a differential purging subsystem that is configured to provide the purged environment for the optical subsystem.