Encoder, position measurement system and lithographic apparatus involving an enclosing device

• Main Authors: Kooiker, Allard Eelco, Pril, Wouter Onno, Tong-Minh, Bryan, Cosijns, Suzanne Johanna Antonetta Geertruda, Baartman, Jan Peter
• Format: Patent
• Language: English
• Published: 08.09.2020
• Subjects: APPARATUS SPECIALLY ADAPTED THEREFOR; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVEREDIN A SINGLE OTHER SUBCLASS; CINEMATOGRAPHY; ELECTROGRAPHY; HOLOGRAPHY; MATERIALS THEREFOR; MEASURING; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS; MEASURING LENGTH, THICKNESS OR SIMILAR LINEARDIMENSIONS; MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR; ORIGINALS THEREFOR; PHOTOGRAPHY; PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES,e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTORDEVICES; PHYSICS; TARIFF METERING APPARATUS; TESTING

An encoder includes an optical component and an enclosing device having a first surface portion and a second surface portion. The first surface portion is arranged to receive from an ambient environment a first radiation beam. The second surface portion is arranged to receive from the ambient environment a second radiation beam. The optical component is arranged to combine the first and second radiation beams. The enclosing device is arranged to propagate the first radiation beam along a first path. The first path is between the first surface portion and the optical component. The enclosing device is arranged to propagate the second radiation beam along a second path. The second path is between the second surface portion and the optical component. The enclosing device is arranged to enclose a space, so as to isolate the first path and the second path from the ambient environment.