Identification and treatment of an efficiency anomaly in a symmetrically ruled grating illuminated at normal incidence

Frédéric E. Vincent, Walter M. Harris, Matthew Beasley, Jason Corliss, Yan Bétrémieux, Lotfi Ben Jaffel, Fred L. Roesler

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


We report the efficiency characteristics of a symmetrically ruled grating in the ± first order with a MgF2 coating that has been optimized for use at 121.6 nm. The grating is used as a beam splitter and dispersing element in an all-reflective spatial heterodyne spectrometer and therefore must be illuminated at normal incidence. A vector analysis of the performance of the grating indicated that acceptable efficiency of 25% would be achieved in this configuration, a result that was initially confirmed in testing at 7° from normal. However, subsequent testing at normal incidence revealed a sharply peaked anomaly that reduced the efficiency by a factor of 2. This anomaly disappeared after the deposit of a second MgF2 coating, although this was accompanied by an overall reduction in efficiency. A second, identical grating was obtained and coated with the second MgF2 recipe. Measurements of this grating show no anomaly at normal incidence and the predicted efficiency at other angles. Here we discuss the characteristics of the anomaly, our steps to address them, and the implications of our findings.

Original languageEnglish (US)
Pages (from-to)346-349
Number of pages4
JournalJournal of Electron Spectroscopy and Related Phenomena
Issue number3-6
StatePublished - Apr 2011


  • Diffraction gratings
  • Efficiency anomalies
  • Spectroscopy
  • VUV

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Radiation
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Spectroscopy
  • Physical and Theoretical Chemistry


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