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Updated: Jul 6, 2026

Implementation of a Reference Interferometer for Nanodetection
Published on: April 26, 2014
Heterodyne interferometer with subatomic periodic nonlinearity
C M Wu1, J Lawall, R D Deslattes
1Physics Laboratory, National Institute of Standards and Technology, Building 221, Room A141, Gaithersburg, Maryland 20899, USA.
Abstract:
A new, to our knowledge, heterodyne interferometer for differential displacement measurements is presented. It is, in principle, free of periodic nonlinearity. A pair of spatially separated light beams with different frequencies is produced by two acousto-optic modulators, avoiding the main source of periodic nonlinearity in traditional heterodyne interferometers that are based on a Zeeman split laser. In addition, laser beams of the same frequency are used in the measurement and the reference arms, giving the interferometer theoretically perfect immunity from common-mode displacement. We experimentally demonstrated a residual level of periodic nonlinearity of less than 20 pm in amplitude. The remaining periodic error is attributed to unbalanced ghost reflections that drift slowly with time.
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