Digital heterodyne interference fringe control system

@article{Heilmann2001DigitalHI,
  title={Digital heterodyne interference fringe control system},
  author={Ralf K. Heilmann and Paul Thomas Konkola and Carl Gang Chen and Gour S. Pati and Mark L. Schattenburg},
  journal={Journal of Vacuum Science \& Technology B},
  year={2001},
  volume={19},
  pages={2342-2346}
}
In traditional interference lithography, interference fringes are typically phase locked to a stationary substrate using analog homodyne photodiode signals that are fed back to control a phase-shifting device such as an electro-optic modulator or a piezoelectrically transduced mirror. Commercially available fringe-locking systems based on this approach often achieve stability of the interference fringes to within a small fraction of the fringe period p (typically ±p/20 peak-to-peak). We… Expand

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