Beam geometry, alignment, and wavefront aberration effects on interferometric differential wavefront sensing

Xiangzhi Yu, S. R. Gillmer, J. D. Ellis

Research output: Contribution to journalArticle

6 Scopus citations


Heterodyne interferometry is a widely accepted methodology with high resolution in many metrology applications. As a functionality enhancement, differential wavefront sensing (DWS) enables simultaneous measurement of displacement, pitch, and yaw using a displacement interferometry system and a single beam incident on a plane mirror target. The angular change is measured using a weighted phase average between symmetrically adjacent quadrant photodiode pairs. In this paper, we present an analytical model to predict the scaling of differential phase signals based on fundamental Gaussian beams. Several numerical models are presented to discuss the effects of physical beam parameters, detector size, system alignment errors, and beam wavefront aberrations on the DWS technique. The results of our modeling predict rotational scaling factors and a usable linear range. Furthermore, experimental results show the analytically predicted scaling factor is in good agreement with empirical calibration. Our three degree-of-freedom interferometer can achieve a resolution of 0.4 nm in displacement and 0.2 μrad in pitch and yaw simultaneously.

Original languageEnglish (US)
Article number125203
JournalMeasurement Science and Technology
Issue number12
Publication statusPublished - Nov 27 2015
Externally publishedYes



  • interferometry
  • metrological instrumentation
  • optical metrology
  • stage calibration

ASJC Scopus subject areas

  • Instrumentation
  • Applied Mathematics

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