A thin-film reflecting interference filter has been designed and constructed for the purpose of suppressing grating harmonics when monochromatizing synchrotron radiation. It consists of a layer of Si evaporated onto a substrate and makes use of interference between wave fronts reflected from the layer–substrate and vacuum–layer interfaces to suppress higher harmonics. The filter has proved useful over the fundamental wavelength range of 400–1200 Å (~30–10 eV), maintaining a rejection ratio of fundamental to second harmonic exceeding 60. Calculations and measurements are presented, and the reflecting interference filter is compared with a critical-angle mirror used for the same purpose.
© 1994 Optical Society of America
Original Manuscript: November 12, 1992
Revised Manuscript: April 1, 1993
Published: March 1, 1994
W. R. Hunter and J. P. Long, "Thin-film interference mirror to suppress grating harmonics in vacuum-ultraviolet radiation," Appl. Opt. 33, 1264-1269 (1994)