Heterodyne interferometer with two spatial-separated polarization beams for nanometrology

摘要

An interferometer having accuracy in displacement measurement of < 1 nm is necessary in nanometrology. To meet the requirement, the periodic nonlinearity mainly caused by polarization and frequency mixings should be less than deep sub-nanometer. In this paper, two spatial-separated polarization beams are used to avoid mixings and then the periodic nonlinearity. The developed interferometer demonstrates a periodic nonlinearity of about 25 pm and a 2 pm/RADIC;Hz in displacement noise level. References: 8