Lens Wheel Configuration for CD17

Angle     Optical Component    Notes
-120 deg  mirror               no change
-60 deg   1% ND filter         removed ZnSe window. 24mm C.A.
0 deg     Open
60 deg    KBr window           removed BaF2. Housed with 25mm C.A.
120 deg   ZnSe lens            d=29.0mm to detector to lens
180 deg   KRS5 lens+10% ND     d=40.6mm

We measured the focal distance for both lenses, using a ceiling light 84mm overhead. 
measured:
f_KRS5(0.63um)=34 mm
f_ZnSe(0.63um)=25 mm 
assuming this corresponds to 0.63 um, the 10um focal lengths are:
f_KRS5(10um)=38.4 mm
f_ZnSe(10um)=28 mm

And for an object distance (lens to echelle grating) of 1m, the image distances for 10um focus are: 

i_KRS5=39.9 mm (compared to installed value of 40.6 mm)
i_ZnSe=28.8 mm (compared to installed value of 29.0 mm)