A description is given of the design principle and the performance of a 6.65 m vertical dispersion off-plane Eagle spectrograph/monochromator (6VOPE) constructed at the Photon Factory. 6VOPE has a unique predisperser system of zero dispersion type that effectively separates the overlapping orders by a simple rotation of the fore-gratings and adjustment of the intermediate slit width. The performance of 6VOPE was examined from the viewpoint of resolution by taking absorption spectra of rare gases in the 50-90 nm region with the 6th to 10th orders. The resolving power was estimated from the separation between two closely lying lines of Ar I at ∼ 79 nm to be ≳ 2.5 × 105, the highest resolving power ever reported for this wavelength region.
ASJC Scopus subject areas
- Nuclear and High Energy Physics