This paper describes the results of transmitted wavefront error (WFE) measurements on a volume phase holographic (VPH) grating operating at a temperature of 120 K. The VPH grating was mounted in a cryogenically compatible optical mount and tested in situ in a cryostat. The nominal root mean square (RMS) wavefront error at room temperature was 19 nm measured over a 50 mm diameter test aperture. The WFE remained at 18 nm RMS when the grating was cooled. This important result demonstrates that excellent WFE performance can be obtained with cooled VPH gratings, as required for use in future cryogenic infrared astronomical spectrometers planned for the European Extremely Large Telescope.
© 2012 Optical Society of America
Optical Design and Fabrication
Original Manuscript: February 16, 2012
Revised Manuscript: March 22, 2012
Manuscript Accepted: March 23, 2012
Published: May 30, 2012
David Lee, Gordon D. Taylor, Thomas E. C. Baillie, and David Montgomery, "Transmitted wavefront error of a volume phase holographic grating at cryogenic temperature," Opt. Lett. 37, 1995-1997 (2012)