Grism Mode

In the short camera spectrographic mode, a grism is positioned at the pupil by the disperser carousel. The grisms are mounted in frames which are in turn attached to the disperser carousel. There are three grism mounting positions for 150 mm diameter grisms. The initial grims selection is intended to include the following:

 

Table 4: Initial grism compliment

Prism	Rulings	Nominal $\lambda$	Nominal	Prism
mat'l	gr/mm	1st. O. (Littrow)	Blaze Angle	angle
F. Silica	150	2000 nm	8.6	8.6
F. Silica	300	2000 nm	17.5	17.5
F. Silica	600	1600 nm	28.7	28.7