Table 2. Grating parameters.

	LEG	MEG	HEG
Range (eV)	150–1200	300–2000	600–2000
k 0 (mm−1)	250	500	1000
a 1 (mm−2)	0.143	0.286	0.571
a 2 (×10−4 mm−3)	0.29	0.56	1.2
a 3 (×10−7 mm−4)	−1.2	−2.4	−4.7