VPHG based GRISMs for MIRC-X/MYSTIC at CHARA

A new set of GRISMs based on Volume Phase Holographic (VPH) gratings is developed for the MIRC-X/MYSTIC beam combiners at the CHARA telescope array. Two of them, for MIRC-X, work in the J band and provide R = 6000; the other two, for MYSTIC, work in the K band and provide R = 4000. The design, manufacturing and test of the dispersing elements are reported and discussed.