TY - JOUR
T1 - Identification and treatment of an efficiency anomaly in a symmetrically ruled grating illuminated at normal incidence
AU - Vincent, Frédéric E.
AU - Harris, Walter M.
AU - Beasley, Matthew
AU - Corliss, Jason
AU - Bétrémieux, Yan
AU - Jaffel, Lotfi Ben
AU - Roesler, Fred L.
N1 - Funding Information: We would like to thank Stephen Rice for the coating services performed at NASA/GSFC Optical Coating Laboratory. We are also grateful to Bruno Touzet (Horiba Jobin-Yvon, Longjumeau, France) for his answers to our questions about the production process of gratings, and to Evgeny Popov (Institut Fresnel, Université de Provence, France) for the interesting conversations about the physics of anomalies. We all acknowledge support from NASA through the grant NNX08AI98G to the University of California Davis, and from CNES through INSPIRE project.
PY - 2011/4
Y1 - 2011/4
N2 - 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.
AB - 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.
KW - Diffraction gratings
KW - Efficiency anomalies
KW - Spectroscopy
KW - VUV
UR - http://www.scopus.com/inward/record.url?scp=79957625671&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79957625671&partnerID=8YFLogxK
U2 - 10.1016/j.elspec.2010.12.033
DO - 10.1016/j.elspec.2010.12.033
M3 - Article
SN - 0368-2048
VL - 184
SP - 346
EP - 349
JO - Journal of Electron Spectroscopy and Related Phenomena
JF - Journal of Electron Spectroscopy and Related Phenomena
IS - 3-6
ER -