Calibration of photoelastic modulators in the vacuum UV

Theodore C. Oakberg, John Trunk, John C. Sutherland

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Measurements of circular dichroism (CD) in the UV and vacuum UV have used photoelastic modulators (PEMs) for high sensitivity (to about 10-6). While a simple technique for wavelength calibration of the PEMs has been used with good results, several features of these calibration curves have not been understood. The authors have calibrated a calcium fluoride PEM and a lithium fluoride PEM using the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory as a light source. These experiments showed calibration graphs that are linear but do not pass through the graph origin. A second `multiple pass' experiment with laser light of a single wavelength, performed on the calcium fluoride PEM, demonstrates the linearity of the PEM electronics. This implies that the calibration behavior results from intrinsic physical properties of the PEM optical element material. An algorithm for generating calibration curves for calcium fluoride and lithium fluoride PEMs has been developed. The calibration curves for circular dichroism measurement for the two PEMs investigated in this study are given as examples.

Original languageEnglish (US)
Pages (from-to)101-111
Number of pages11
JournalProceedings of SPIE - The International Society for Optical Engineering
Issue number1
StatePublished - Nov 15 2000
Externally publishedYes


  • Chiral molecule
  • Circular dichroism
  • Photoelastic modulator
  • Synchrotron
  • UV
  • Vacuum UV

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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